CN110799321B

CN110799321B - Method for manufacturing circuit component and circuit component

Info

Publication number: CN110799321B
Application number: CN201880042036.2A
Authority: CN
Inventors: 游佐敦; 山本智史; 后藤英斗
Original assignee: Maxell Ltd
Current assignee: Maxell Ltd
Priority date: 2017-06-26
Filing date: 2018-06-25
Publication date: 2022-06-17
Anticipated expiration: 2038-06-25
Also published as: KR102632455B1; WO2019004132A1; KR20200021939A; JPWO2019004132A1; CN110799321A; JP7121004B2

Abstract

The invention provides a circuit component meeting the light weight requirement of automobile components and the like. A circuit member comprising a base material which is a foamed molded body containing a thermoplastic resin and a circuit pattern formed on the base material.

Description

Method for manufacturing circuit component and circuit component

Technical Field

The present invention relates to a method for manufacturing a circuit member (molded circuit member) and a circuit member (molded circuit member).

Background

In recent years, with the trend toward weight reduction and electric drive of automobiles, there has been a trend to replace metal parts of automobiles with foamed resin parts that are lightweight and have insulation properties. Therefore, a large number of studies and practical uses have been made on a method for producing a foamed molded article (foam molding). Conventionally, polypropylene (PP) and acrylonitrile-butadiene-styrene copolymer resin (ABS) have been used as general-purpose engineering plastics (engineering plastics). Further, glass fiber reinforced resins such as polyamide 6 and polyamide 66 having a certain degree of heat resistance are also used for foam molding. The foaming agents used in foam molding are roughly classified into 2 types, physical foaming agents and chemical foaming agents, and it is difficult to use chemical foaming agents for high-melting materials. For this reason, foam injection molding methods using a high-pressure supercritical fluid as a physical foaming agent are used for foam molding of the glass fiber reinforced resin and the like having high heat resistance (for example, patent documents 1 to 3).

The general engineering plastic has a heat resistance of about 100 ℃, and super engineering plastics (special engineering plastics) such as polyphenylene sulfide (PPS) and Liquid Crystal Polymer (LCP) having a heat resistance of 150 ℃ or higher are used in applications where the general engineering plastic is used in a higher temperature environment. PPS is a special engineering plastic with excellent cost performance and fastest growing application in automobile parts. LCP is used in small components such as high-precision connectors. Patent documents 4 and 5 disclose methods for producing PPS foamed molded articles.

In recent years, MID (Molded Interconnected Device) has been put to practical use in smart phones and the like, and it is expected that the application in the automobile field will expand in the future. MID is a device in which a three-dimensional circuit is formed on the surface of a molded body using a metal film, and can contribute to weight reduction, thickness reduction, and reduction in the number of parts of a product (for example, patent documents 6 and 7).

MID mounted Light Emitting Diodes (LEDs) have also been proposed. Since the LED generates heat by being energized, heat must be radiated from the back surface, and it is important to improve the heat radiation performance of the MID. Patent documents 8 and 9 propose composite members in which an MID and a metal heat-emitting material are integrated.

Further, a method of improving the heat radiation property of a resin molded product itself by mixing a conductive filler with a resin and molding the mixture has been proposed (for example, patent document 10).

Documents of the prior art

Patent document

Patent document 1: japanese patent No. second 625576 publication

Patent document 2: japanese patent No. 3788750

Patent document 3: japanese patent No. 4144916

Patent document 4: japanese patent laid-open publication No. 2013-60508

Patent document 5: japanese laid-open patent publication No. 2012-251022

Patent document 6: european patent No. 274288 publication

Patent document 7: japanese patent No. 5022501

Patent document 8: japanese patent No. 3443872

Patent document 9: japanese patent laid-open publication No. 2017-199803

Patent document 10: japanese laid-open patent publication No. 2015-108058

Disclosure of Invention

Problems to be solved by the invention

In order to meet the demand for weight reduction of automobile parts, molded circuit parts such as MIDs disclosed in patent documents 6 and 7 need to be further weight reduced. Therefore, it is desired to use a foamed molded article having a low specific gravity for molding a circuit member to reduce the weight of the molded circuit member. The present invention solves the above problems and provides a lightweight molded circuit component.

The methods for producing PPS foamed molded articles disclosed in patent documents 4 and 5 include a step of holding a PPS molded article in an inert gas atmosphere under pressure to allow the inert gas to permeate therethrough, and a step of heating PPS permeated with the inert gas at normal pressure to foam the PPS foamed molded article, and are so-called batch-type production methods. Therefore, the productivity is low as compared with continuous molding such as injection molding or extrusion molding.

The foam molding methods using a physical foaming agent disclosed in patent documents 1 to 3 are continuous molding with high productivity, and are foam molding techniques that do not select a resin. Therefore, in principle, it is considered that the foam molding of a special engineering plastic such as PPS can be performed by the methods disclosed in patent documents 1 to 3. However, in recent years, very high heat resistance has been required for automobile parts. According to the studies of the present inventors, it has been found that a foamed molded article produced by using a conventional high-pressure physical foaming agent and a molded circuit member using the same, as disclosed in patent documents 1 to 3, cannot obtain sufficient heat resistance even when a special engineering plastic is used as a resin material.

The present invention solves the above problems and provides a method for manufacturing a molded circuit component which includes continuous molding with high productivity, has high heat resistance, and is lightweight.

Further, if the resin molded body serving as a base material of the circuit component such as the MID has a sufficient heat radiation performance, the metal heat radiation member disclosed in patent documents 8 and 9 is not necessary, and the cost of the circuit component can be reduced. However, if it is desired to add a conductive filler such as that disclosed in patent document 10 to a thermoplastic resin to obtain heat dissipation properties required for electronic components, the fluidity of the thermoplastic resin is reduced during molding. As a result, moldability is reduced, and sufficient dimensional accuracy cannot be obtained for the resin molded article.

If the pressure holding is increased in order to improve the dimensional accuracy of the resin molded article, burrs may be generated in the resin molded article. When the burrs are generated, secondary processing for removing the burrs is required. Further, if the mold is molded by increasing the clamping pressure in order to suppress the occurrence of burrs, there is a problem that the life of the mold is shortened. These problems increase the manufacturing cost of the circuit components and reduce mass productivity.

The present invention solves these problems, and provides a circuit component (MID) using a base material of a resin molded body, which can achieve both mass productivity and heat dissipation.

Means for solving the problems

According to a first aspect of the present invention, there is provided a circuit member comprising a base material which is a foamed molded body containing a thermoplastic resin, and a circuit pattern formed on the base material.

In this embodiment, the thermoplastic resin may contain a super engineering plastic, and the rate of change in the thickness of the circuit member due to heating may be-2% to 2% when the circuit member is heated to maintain the surface temperature of the circuit member at 240 ℃ to 260 ℃ for 5 minutes. The heating of the aforementioned circuit components may be performed using a reflow oven.

In the present embodiment, the circuit member is the foamed molded body containing the thermoplastic resin and the insulating heat conductive filler and having a density reduction rate of 0.5% to 10%, and has the base material including a mounting surface and a back surface opposite to the mounting surface, the circuit pattern formed on the surface of the base material including the mounting surface, and the mounting member mounted on the mounting surface of the base material and electrically connected to the circuit pattern, and a distance from the mounting surface to the back surface may be 0.1mm or more in a portion of the base material where the mounting member is mounted. The density reduction rate of the base material may be 1 to 7%. Further, the distance from the mounting surface to the rear surface may exceed 0.5mm at the portion of the base material where the mounting member is mounted, and a foam cell (foam セル) may be provided between the mounting surface and the rear surface. The rear surface may be formed with a recess defined by a side wall and a bottom surface, the mounting member may be mounted on the mounting surface corresponding to the bottom surface, and a distance from the mounting surface to the bottom surface may be 0.1mm to 1.5 mm. The area of the bottom surface of each of the mounting members disposed on the mounting surface corresponding to the bottom surface may be 0.4cm²～4cm²。

A non-through hole or a through hole may be formed from the mounting surface to the bottom surface, and an electroless plating film may be formed on an inner wall of the hole. In addition, a recess may be formed in the mounting surface at a portion of the base member to which the mounting member is attached, and an electroless plating film may be formed on a surface of the recess.

The mounting member may be an LED, and the circuit pattern may include an electroless plating film. The rear surface may not be provided with a heat radiation member. The thermoplastic resin may contain a super engineering plastic, and the super engineering plastic may contain polyphenylene sulfide or a liquid crystal polymer.

According to a second aspect of the present invention, there is provided a method for manufacturing an electrical circuit member, comprising using a plasticizing cylinder having a plasticizing region for plasticizing and melting a thermoplastic resin to form a molten resin and a starvation region for causing the molten resin to assume a starved state, the plasticizing cylinder being provided with an inlet for introducing a physical blowing agent into the starvation region; the manufacturing method comprises the following steps: plasticizing and melting the thermoplastic resin in the plasticizing area to form the molten resin, introducing a pressurized fluid containing the physical foaming agent at a fixed pressure into the starving area and maintaining the starving area at the fixed pressure, causing the molten resin to assume a starved state in the starving area, bringing the molten resin in the starving area into contact with the pressurized fluid containing the physical foaming agent at the fixed pressure in the state where the starving area is maintained at the fixed pressure, molding the molten resin in contact with the pressurized fluid containing the physical foaming agent into a foam molded body, and forming a circuit pattern on the surface of the foam molded body; the thermoplastic resin is super engineering plastic, and the fixed pressure is 0.5MPa to 12 MPa.

In this embodiment, the super engineering plastic may contain polyphenylene sulfide or a liquid crystal polymer. The super engineering plastic may contain polyphenylene sulfide, and the fixed pressure may be 2MPa to 12 MPa. The physical blowing agent may be nitrogen.

The molten resin may be pressurized by the pressurized fluid containing the physical foaming agent in the starved region, or the starved region may be kept at the constant pressure during the production of the foamed molded article. The plasticizing cylinder may have an introduction speed adjusting container connected to the introduction port, and the manufacturing method may further include supplying the pressurized fluid containing the physical foaming agent to the introduction speed adjusting container, and introducing the pressurized fluid containing the physical foaming agent at a fixed pressure from the introduction speed adjusting container to the starvation zone. The introduction port may be opened all the time, and the fixed pressure may be maintained in the introduction speed adjustment vessel and the starved area during the production of the foamed molded article.

The forming of the circuit pattern on the surface of the foamed molded article may include: forming a catalytic activity suppressing layer containing a polymer having at least one of an amide group and an amino group on the surface of the foam molded body, heating or irradiating a part of the surface of the foam molded body on which the catalytic activity suppressing layer is formed with light, applying an electroless plating catalyst to the surface of the foam molded body which has been heated or irradiated with light, and bringing the surface of the foam molded body to which the electroless plating catalyst has been applied into contact with an electroless plating solution to form the electroless plating film on a heated portion or a light-irradiated portion of the surface. The aforementioned polymer may be a hyperbranched polymer.

Effects of the invention

The invention can provide a lightweight circuit component (molded circuit component).

Drawings

Fig. 1 is a flowchart showing a method for producing a foamed molded article according to a first embodiment.

Fig. 2 is a schematic diagram showing an apparatus for producing a molded foam used in the first embodiment.

Fig. 3 is a flowchart showing a method of forming a circuit pattern on the surface of a foamed molded body in the first embodiment.

Fig. 4 is a diagram illustrating a method for forming a circuit pattern on the surface of a foamed molded article according to the first embodiment.

In fig. 5, fig. 5(a) is a schematic top view of a circuit component according to a second embodiment, and fig. 5(B) is a schematic cross-sectional view taken along line B1-B1 in fig. 5 (a).

Fig. 6 is a partially enlarged view of the circuit component shown in fig. 5 (b).

In fig. 7, fig. 7(a) is a top view showing a structure in the manufacturing process of the circuit part shown in fig. 5(a), and fig. 7(B) is a cross-sectional view of line B3-B3 of fig. 7 (a).

In fig. 8, fig. 8(a) is a top view showing a structure in another manufacturing process of the circuit part shown in fig. 5(a), and fig. 8(B) is a cross-sectional view of line B4-B4 of fig. 8 (a).

Fig. 9 is a schematic cross-sectional view of a circuit member of modification 1 of the second embodiment.

Fig. 10 is a schematic cross-sectional view of a circuit member of modification 2 of the second embodiment.

Detailed Description

[ first embodiment ]

The method for manufacturing a molded circuit component according to the present embodiment will be described with reference to the flowchart shown in fig. 1. In the present embodiment, first, a foam molded body is produced (steps S1 to S5 in fig. 1), and a circuit pattern is formed on the surface of the foam molded body (step S6 in fig. 1) to obtain a molded circuit component. Here, the term "molded circuit component" means a component in which an electric circuit is formed on the surface of a resin molded body.

< apparatus for producing foamed molded article >

First, a production apparatus for producing a foamed molded article used in the present embodiment will be described. In the present embodiment, a foamed molded body is produced using a production apparatus (injection molding apparatus) 1000 shown in fig. 2. The manufacturing apparatus 1000 mainly includes a plasticizing cylinder 210 having a screw 20 provided therein, a tank 100 as a physical blowing agent supply mechanism for supplying a physical blowing agent to the plasticizing cylinder 210, a mold clamping unit (not shown) having a mold, and a control device (not shown) for controlling the operation of the plasticizing cylinder 210 and the mold clamping unit. In the plasticizing cylinder 210, the molten resin that is plasticized flows from the right-hand side to the left-hand side in fig. 2. Therefore, inside the plasticizing cylinder 210 of the present embodiment, the right-hand side in fig. 2 is defined as "upstream" or "rear", and the left-hand side is defined as "downstream" or "front".

The plasticizing cylinder has a plasticizing zone 21 where the thermoplastic resin is plasticized and melted to form molten resin, and a starvation zone 23 where the molten resin assumes a starvation state on the downstream side of the plasticizing zone 21. The "starved state" is an unfilled state in which the molten resin is not filled in the starved zone 23. Therefore, a space other than the portion occupied by the molten resin exists in the starved area 23. Further, an inlet port 202 for introducing a physical foaming agent into the starved area 23 is formed, and an introduction speed adjusting container 300 is connected to the inlet port 202. The tank 100 supplies the physical foaming agent to the plasticizing cylinder 210 via the introduction speed adjusting container 300.

The manufacturing apparatus 1000 has only 1 starvation area 23, but the manufacturing apparatus used in the present embodiment is not limited to this. For example, in order to promote the penetration of the physical blowing agent into the molten resin, the apparatus may be configured to have a plurality of starvation areas 23 and inlets 202 formed therein, and to introduce the physical blowing agent into the plasticizing cylinder 210 through the plurality of inlets 202. The manufacturing apparatus 1000 is an injection molding apparatus, but the manufacturing apparatus used in the present embodiment is not limited to this, and may be an extrusion molding apparatus, for example.

< method for manufacturing molded circuit component >

(1) Plasticizing and melting of thermoplastic resin

First, the thermoplastic resin is plasticized and melted in the plasticizing zone 21 of the plasticizing cylinder 210 to form a molten resin (step S1 of fig. 1). In the present embodiment, as the thermoplastic resin, super engineering plastic (hereinafter, appropriately referred to as "special engineering plastic") is preferably used. Generally, plastics having a continuous use temperature of 150 ℃ or higher are classified as special engineering plastics, and therefore, the definition of special engineering plastics in the specification of the present application is also in accordance with this classification. Most molecular chains of the special engineering plastics contain benzene rings, so the molecular chains are coarse and hard. Even if the ambient temperature is high, the molecules are hard to move, and therefore, the heat resistance is excellent. Further, some fluororesins have excellent heat resistance even if they do not have a benzene ring structure, and are classified as special engineering plastics. Since the fluororesin is very stable in combination with carbon.

Special engineering plastics are roughly classified into amorphous (transparent) resins and crystalline resins. Examples of the amorphous (transparent) resin include polyphenylsulfone (PPSU), Polysulfone (PSU), Polyarylate (PAR), and Polyetherimide (PEI); examples of the crystalline resin include Polyetheretherketone (PEEK), polyphenylene sulfide (PPS), Polyethersulfone (PES), polyamide-imide (PAI), Liquid Crystal Polymer (LCP), and polyvinylidene fluoride (PVDF). The special engineering plastic of the present embodiment may be used alone or in combination of two or more of them, and a polymer alloy containing these engineering plastics may be used. As the special engineering plastic used in the present embodiment, a crystalline resin which is easily formed into fine cells is preferable, and among them, polyphenylene sulfide (PPS) and a Liquid Crystal Polymer (LCP) are more preferable.

Polyphenylene Sulfide (PPS) has advantages such as being relatively inexpensive, chemically stable, easily controllable in dimensional accuracy, and high in strength, and thus the demand is increasing mainly for automobile parts. However, PPS has problems that burrs are likely to be formed during molding, and that if mixed with long glass fibers or the like, warping is likely to occur, resulting in a large specific gravity. In the present embodiment, by foam molding PPS, burrs and warpage can be suppressed, and the specific gravity can be further reduced. Since the Liquid Crystal Polymer (LCP) has a large dependency on the shear rate of the molten resin, it is difficult to generate burrs during molding, and high dimensional accuracy can be obtained even in a thin-walled molded part. Among automotive parts, LCP is used in connectors requiring high heat resistance. On the other hand, LCP has problems of high price and large specific gravity. In the present embodiment, by foam molding the LCP, the specific gravity can be reduced, and the amount of use is reduced compared to a solid molded article (non-foamed molded article) of the same size, and therefore, the cost is also reduced.

Various inorganic fillers such as glass fiber, talc, and carbon fiber may be kneaded with the thermoplastic resin of the present embodiment. By mixing an inorganic filler that functions as a foam nucleus agent and an additive that increases melt tension with a thermoplastic resin, it is possible to miniaturize the foam cells. The thermoplastic resin of the present embodiment may contain various other common additives as needed.

In the present embodiment, only a special engineering plastic is used as the thermoplastic resin, and a general-purpose thermoplastic resin other than the special engineering plastic may be used in combination depending on the use of the foamed molded article to the extent that the heat resistance of the foamed molded article is not affected. In the present embodiment, the main component of the thermoplastic resin constituting the foamed molded article is the special engineering plastic, and for example, the proportion of the special engineering plastic in the thermoplastic resin constituting the foamed molded article is preferably 60 to 100% by weight, and more preferably 95 to 100% by weight. In the present embodiment, a physical blowing agent is used as the blowing agent, and a chemical blowing agent is not used. Therefore, the special engineering plastic as the thermoplastic resin of the present embodiment does not contain a chemical foaming agent. The melting temperature of special engineering plastics is high, so that it is difficult to use chemical foaming agents together.

In the present embodiment, the thermoplastic resin is plasticized and melted in the plasticizing cylinder 210 having the screw 20 provided therein as shown in fig. 2. The plasticizing cylinder 210 is heated by a belt heater (not shown) provided on the outer wall surface of the plasticizing cylinder 210, and the thermoplastic resin is plasticized and melted by further adding shear heat generated by the rotation of the screw 20.

(2) Pressure maintenance in starvation zone

Next, a physical foaming agent of a fixed pressure is introduced into starvation zone 23 to maintain starvation zone 23 at the fixed pressure (step S2 in fig. 1).

A pressurized fluid is used as the physical blowing agent. The term "fluid" in the present embodiment means any of a liquid, a gas, and a supercritical fluid. In addition, from the viewpoint of cost and environmental load, the physical blowing agent is preferably carbon dioxide, nitrogen gas, or the like. Since the pressure ratio of the physical foaming agent of the present embodiment is low, for example, a fluid that is decompressed to a fixed pressure by a decompression valve from a tank that stores a fluid such as a nitrogen tank, a carbon dioxide tank, or an air tank and is taken out can be used. In this case, since the booster device is not required, the cost of the entire manufacturing apparatus can be reduced. If necessary, a fluid whose pressure is increased to a predetermined pressure may be used as the physical foaming agent. For example, when nitrogen is used as the physical blowing agent, the physical blowing agent can be produced by the following method. First, nitrogen gas is purified by passing through a nitrogen separation membrane while compressing air in the atmosphere by a compressor. Next, the purified nitrogen gas is pressurized to a predetermined pressure using a booster pump, a syringe pump, or the like, to produce a physical blowing agent. In addition, compressed air may also be used as a physical blowing agent. In the present embodiment, the forced shear kneading of the physical blowing agent and the molten resin is not performed. Therefore, even if compressed air is used as the physical blowing agent, oxygen having low solubility in the molten resin is difficult to dissolve in the molten resin, and oxidative degradation of the molten resin can be suppressed.

The pressure of the physical blowing agent introduced in starvation zone 23 is fixed, and the pressure in starvation zone 23 is maintained at the same fixed pressure as the physical blowing agent introduced. The pressure of the foaming agent is, for example, 0.5 to 12MPa, preferably 2 to 12MPa, more preferably 2 to 10MPa, and still more preferably 2 to 8 MPa. The pressure of the physical blowing agent is preferably 1MPa to 6 MPa. The optimum pressure varies depending on the type of the molten resin, and by setting the pressure of the physical blowing agent to 0.5MPa or more, the physical blowing agent in an amount necessary for foaming can be made to permeate into the molten resin, and the foamability of the foamed molded article can be improved. Further, by setting the pressure of the physical foaming agent to 12MPa or less, the heat resistance of the foamed molded article is improved, the occurrence of the swirl marks is suppressed, and the load on the apparatus can be further reduced. The "fixed" pressure of the physical blowing agent for pressurizing the molten resin means that the pressure is preferably within ± 20%, more preferably within ± 10% of a predetermined pressure. The pressure in the starvation zone is measured, for example, by a pressure sensor 27 disposed in the starvation zone 23 of the plasticizing cylinder 210. Further, as the screw 20 advances and retreats, the starvation region 23 moves in the forward and backward directions in the plasticizing cylinder 210, and the pressure sensor 27 shown in fig. 2 is provided at a position existing in the starvation region 23 at all times, of the foremost position and the rearmost position of the starvation region 23. Further, the position opposite to the introduction port 202 is also always in the starvation zone 23. Therefore, although the pressure sensor 27 is not provided at a position facing the introduction port 202, the pressure indicated by the pressure sensor 27 is substantially the same as the pressure at the position facing the introduction port 202. In the present embodiment, only the physical blowing agent is introduced into the starved area 23, and a pressurized fluid other than the physical blowing agent may be simultaneously introduced into the starved area 23 to such an extent that the effect of the present invention is not impaired. In this case, the pressurized fluid containing physical blowing agent introduced into starvation zone 23 has the above-mentioned fixed pressure.

In the present embodiment, as shown in fig. 2, the physical foaming agent is supplied from the tank 100 to the starvation area 23 through the inlet 202 via the inlet speed adjusting container 300. The physical blowing agent is depressurized to a predetermined pressure by a pressure reducing valve 151, and then introduced into the starvation zone 23 from the inlet 202 without passing through a pressure increasing device or the like. In the present embodiment, the introduction amount, the introduction time, and the like of the physical blowing agent introduced into the plasticizing cylinder 210 are not controlled. Therefore, a mechanism for controlling these components is not necessary, and for example, a drive valve such as a check valve or a solenoid valve is not necessary, and the introduction port 202 has no drive valve and is always open. In the present embodiment, a fixed physical blowing agent pressure is maintained from the pressure reducing valve 151 through the introduction speed adjustment container 300 to the starvation area 23 in the plasticizing cylinder 210 by the physical blowing agent supplied from the tank 100.

The physical blowing agent inlet port 202 has a larger inner diameter than the physical blowing agent inlet port of the conventional production apparatus. The reason why the inner diameter of the inlet 202 can be increased in this way is that the amount of molten resin in the starved area 23 opposite the inlet 202 during molding is smaller than in the conventional manufacturing apparatus. Therefore, even a physical foaming agent having a low pressure can be efficiently introduced into the plasticizing cylinder 210. Further, even when a part of the molten resin is solidified by being brought into contact with the inlet 202, the inlet can function as a full seal without being completely closed because of the large inner diameter. For example, when the inner diameter of the plasticizing cylinder 210 is large, that is, when the outer diameter of the plasticizing cylinder is large, the inner diameter of the introduction port 202 is easily made large. On the other hand, if the inner diameter of the inlet 202 is excessively large, the molten resin stays, which causes molding defects, and the introduction speed adjusting vessel 300 connected to the inlet 202 becomes large, which increases the cost of the entire apparatus. Specifically, the inner diameter of the introduction port 202 is preferably 20% to 100%, more preferably 30% to 80%, of the inner diameter of the plasticizing cylinder 210. Alternatively, the inner diameter of the introduction port 202 is preferably 3mm to 150mm, more preferably 5mm to 100mm, regardless of the inner diameter of the plasticizing cylinder 210. Here, the inner diameter of the introduction port 202 means the inner diameter of the opening portion in the inner wall 210a of the plasticizing cylinder 210. The shape of the introduction port 202, that is, the shape of the opening in the inner wall 210a of the plasticizing cylinder 210 is not limited to a perfect circle, and may be an ellipse or a polygon. When the shape of the inlet 202 is an ellipse or a polygon, the diameter of a perfect circle having the same area as that of the inlet 202 is defined as "the inner diameter of the inlet 202".

Next, the introduction speed adjustment container 300 connected to the introduction port 202 will be described. The introduction speed adjusting container 300 connected to the introduction port 202 has a volume equal to or larger than a certain value, and thus the flow rate of the physical blowing agent introduced into the plasticizing cylinder 210 is reduced, and a time period during which the physical blowing agent can stay in the introduction speed adjusting container 300 can be secured. The introduction speed adjustment container 300 is directly connected to the plasticizing cylinder 210 heated by a belt heater (not shown) disposed around the plasticizing cylinder, and the heat of the plasticizing cylinder 210 is transferred to the introduction speed adjustment container 300. As a result, the physical blowing agent in the introduction speed control vessel 300 is heated, the temperature difference between the physical blowing agent and the molten resin is reduced, and the amount of the physical blowing agent dissolved (permeated) in the molten resin can be stabilized by suppressing an extreme decrease in the temperature of the molten resin with which the physical blowing agent comes into contact. That is, the introduction speed adjusting container 300 functions as a buffer container having a function of heating the physical foaming agent. On the other hand, if the volume of the introduction speed adjustment container 300 is too large, the cost of the entire apparatus increases. The volume of introduction speed adjustment vessel 300 also depends on the amount of molten resin present in starvation zone 23, and is preferably 5mL to 20L, more preferably 10mL to 2L, and still more preferably 10mL to 1L. By setting the volume of the introduction speed adjustment container 300 within this range, the time during which the physical blowing agent can stay can be ensured in consideration of cost.

As will be described later, the physical blowing agent permeates through contact with the molten resin and is consumed in the plasticizing cylinder 210. In order to keep the pressure in starvation zone 23 constant, the amount of physical blowing agent consumed in starvation zone 23 is introduced from introduction rate adjusting vessel 300. If the volume of the introduction speed adjustment container 300 is too small, the frequency of replacement of the physical blowing agent increases, and therefore the temperature of the physical blowing agent becomes unstable, and as a result, the supply of the physical blowing agent may become unstable. Therefore, the introduction speed adjustment container 300 preferably has a volume in which the physical foaming agent consumed in the plasticizing cylinder can be retained for 1 to 10 minutes. Further, for example, the volume of the introduction speed adjustment vessel 300 is preferably 0.1 to 5 times, more preferably 0.5 to 2 times the volume of the starvation area 23 to which the introduction speed adjustment vessel 300 is connected. In the present embodiment, the volume of the starvation zone 23 means the volume of a region (23) in the empty plasticizing cylinder 210 containing no molten resin, where a portion where the diameter of the shaft of the screw 20 and the depth of the screw flight are constant is located. Further, since the introduction port 202 is always open, the introduction speed adjusting container 300 and the starved area 23 are always kept at a constant pressure of the physical blowing agent during the production of the foamed molded article.

(3) The molten resin is starved

Next, the molten resin is made to flow to the starvation area 23, and the molten resin is made to be in a starved state in the starvation area 23 (step S3 of fig. 1). The starved state is determined by the balance between the amount of molten resin supplied from the upstream side of the starvation zone 23 to the starvation zone 23 and the amount of molten resin supplied from the starvation zone 23 to the downstream side thereof, and if the former is small, the starved state is assumed.

In the present embodiment, the compressing region 22 in which the pressure is increased by compressing the molten resin is provided upstream of the starvation region 23, and the molten resin is starved in the starvation region 23. In the compression zone 22, a large diameter portion 20A is provided in which the diameter of the shaft of the screw 20 is made larger (thicker) than the plasticizing zone 21 located on the upstream side and the screw flight becomes shallower in steps, and further, a seal portion 26 is provided adjacently on the downstream side of the large diameter portion 20A. The seal portion 26 has a large (thick) diameter of the shaft of the screw 20, and is formed with a plurality of shallow grooves instead of the screw flight in the shaft of the screw 20 without providing the screw flight, as in the large diameter portion 20A. The large diameter portion 20A and the seal portion 26 can reduce the gap between the inner wall of the plasticizing cylinder 210 and the screw 20 by increasing the diameter of the shaft of the screw 20, and reduce the amount of resin supplied to the downstream, thereby increasing the flow resistance of the molten resin. Therefore, in the present embodiment, the large diameter portion 20A and the seal portion 26 are means for increasing the flow resistance of the molten resin. Further, the seal portion 26 also achieves the effect of suppressing the backflow of the physical blowing agent, that is, the movement of the physical blowing agent from the downstream side to the upstream side of the seal portion 26.

Due to the presence of the large diameter portion 20A and the seal portion 26, the flow rate of the resin supplied from the compression zone 22 to the starvation zone 23 is reduced, the molten resin is compressed and the pressure is raised in the compression zone 22 on the upstream side, and the molten resin is in an unfilled state (starved state) in the starvation zone 23 on the downstream side. In order to promote the starvation state of the molten resin, the screw 20 has a structure in which the shaft of the portion located in the starvation zone 23 is smaller (thinner) in diameter than the portion located in the compression zone 22 and the screw thread is deep. Further, the screw 20 preferably has a structure in which the shaft of the portion located there throughout the starvation zone 23 has a smaller (thinner) diameter than the portion located in the compression zone 22 and the screw thread is deep. Further, it is preferred that the diameter of the shaft of the screw 20 and the depth of the screw flight be substantially constant throughout the starvation zone 23. This makes it possible to maintain the pressure in the starvation zone 23 substantially constant, and to stabilize the starved state of the molten resin. In the present embodiment, as shown in fig. 2, the starvation area 23 is formed in a portion of the screw 20 where the diameter of the shaft of the screw 20 and the depth of the screw flight are fixed.

The mechanism for increasing the flow resistance of the molten resin provided in the compression zone 22 is not particularly limited as long as it is a mechanism for temporarily reducing the flow path area through which the molten resin passes in order to restrict the flow rate of the resin supplied from the compression zone 22 to the starvation zone 23. In the present embodiment, both the large diameter portion 20A of the screw and the seal portion 26 are used, and only one may be used. Examples of the mechanism for increasing the flow resistance other than the large diameter portion 20A and the seal portion 26 of the screw include a structure in which the screw flight is disposed in the opposite direction to the other portions, and a labyrinth structure provided on the screw.

The means for increasing the flow resistance of the molten resin may be provided on the screw as a ring or the like which is a separate member from the screw, or may be provided integrally with the screw as a part of the screw structure. If the mechanism for increasing the flow resistance of the molten resin is provided as a ring or the like which is a member different from the screw, the size of the gap portion which is the molten resin flow path can be changed by changing the ring, and therefore, there is an advantage that the size of the flow resistance of the molten resin can be easily changed.

In addition to the mechanism for increasing the flow resistance of the molten resin, a backflow prevention mechanism (closing mechanism) for preventing the backflow of the molten resin from the upstream compression zone 22 from the starvation zone 23 is provided between the compression zone 22 and the starvation zone 23, whereby the molten resin in the starvation zone 23 can be brought into a starved state. Examples of the closing mechanism include a ring and a steel ball which can be moved upstream by the pressure of the physical blowing agent. However, since the backflow prevention mechanism needs a driving unit, there is a possibility that resin may be accumulated. Therefore, a mechanism for increasing the flow resistance without a driving portion is preferable.

In the present embodiment, the supply amount of the thermoplastic resin to the plasticizing cylinder 210 may be controlled in order to stabilize the starvation state of the molten resin in the starvation zone 23. Because if the supply amount of the thermoplastic resin is excessive, it is difficult to maintain the starved state. In the present embodiment, a general feed screw 212 is used to control the supply amount of the thermoplastic resin. Since the supply amount of the thermoplastic resin is limited, the measurement speed of the molten resin in the starvation region 23 is faster than the plasticizing speed of the compression region 22. As a result, the density of the molten resin in the starved area 23 is stably reduced, and the penetration of the physical blowing agent into the molten resin is promoted.

In the present embodiment, in order to secure the contact area and contact time between the molten resin and the physical blowing agent, it is preferable that the length of the starved area 23 in the flow direction of the molten resin is long, but if it is too long, the molding cycle and the screw length disadvantageously become long. Therefore, the length of the starved zone 23 is preferably 2 to 12 times, more preferably 4 to 10 times the inner diameter of the plasticizing cylinder 210. Furthermore, it is preferred that the length of the starved area 23 covers the entire range of measurement strokes in injection molding. That is, the length of the starved region 23 in the flow direction of the molten resin is preferably equal to or longer than the length of the measurement stroke in the injection molding. By setting the length of the starvation region 23 to be equal to or longer than the length of the measurement stroke as the screw 20 moves forward and backward along with the measurement and injection of the plasticization of the molten resin, the inlet 202 can be arranged (can be formed) in the starvation region 23 at all times in the production of the foamed molded article. In other words, even if the screw 20 moves forward and backward in the production of the foamed molded article, the region other than the starved area 23 does not enter the position of the inlet 202. Thereby, the physical foaming agent introduced from the inlet 202 is introduced up to the starved area 23 in the production of the foamed molded article. By providing the starvation zone with a sufficient and appropriate size (length) in this manner, introducing a physical blowing agent of a fixed pressure therein, it is easier to maintain the starvation zone 23 at a fixed pressure. In the present embodiment, as shown in fig. 2, the length of starvation zone 23 is substantially the same as the diameter of the shaft of screw 20 and the length of the portion of screw flight of screw 20 where the depth is fixed.

Further, a flow rate adjustment zone 25 may be provided between the compression zone 22 and the starvation zone 23. Comparing the flow rate of the molten resin in the compression zone 22 upstream of the flow rate adjustment zone 25 with the flow rate of the molten resin in the starvation zone 23 downstream, the flow rate of the molten resin in the starvation zone 23 is faster. The present inventors have found that the foamability of the foamed molded article to be produced can be improved by providing the flow rate adjusting region 25 as a buffer region between the compression region 22 and the starved region 23 and suppressing such a rapid change (rise) in the flow rate of the molten resin. The reason why the foamability of the foamed molded article is improved by providing the flow rate adjusting region 25 as the buffer region between the compression region 22 and the starved region 23 is not clear in detail, but it is presumed that the following may be one reason: since the molten resin stays in the flow velocity adjusting zone 25, the physical blowing agent and the molten resin flowing from the starvation zone 23 are forcibly kneaded, and the kneading time becomes long. In the present embodiment, the molten resin and the physical blowing agent are decompressed and recompressed by providing a decompression section and a compression section in a portion of the plasticizing screw 20 located in the flow velocity adjusting zone 25 shown in fig. 2 to change the flow path area. Further, the flow rate of the molten resin is adjusted by providing a notch in the screw flight. The decompression section and the compression section can be formed, for example, by changing the depth of the screw flight, in other words, by changing the size (thickness) of the screw diameter.

(4) Contacting molten resin with physical blowing agent

Next, in a state where the starved region 23 is maintained at a fixed pressure, the molten resin in the starved state in the starved region 23 is brought into contact with the physical blowing agent at a fixed pressure (step S4 of fig. 1). That is, in the starvation zone 23, the molten resin is pressurized with a physical blowing agent at a fixed pressure. Since the starved region 23 is a space in which the molten resin is not filled (starved state) and the physical blowing agent can exist, the physical blowing agent can be brought into effective contact with the molten resin. The physical blowing agent in contact with the molten resin permeates into the molten resin and is consumed. If the physical blowing agent is consumed, the physical blowing agent staying in the introduction speed adjustment vessel 300 is supplied to the starvation area 23. Thus, the pressure in starvation zone 23 is maintained at a fixed pressure and the molten resin continues to contact the fixed pressure physical blowing agent.

In conventional foam molding using a physical blowing agent, a predetermined amount of a high-pressure physical blowing agent is forcibly introduced into a plasticizing cylinder for a predetermined time. Therefore, it is necessary to increase the pressure of the physical blowing agent to a high pressure and accurately control the amount, time, and the like of the physical blowing agent introduced into the molten resin, and the physical blowing agent is brought into contact with the molten resin for only a short introduction time. In the present embodiment, however, the physical blowing agent is not forcibly introduced into the plasticizing cylinder 210, but the physical blowing agent of a fixed pressure is continuously supplied into the plasticizing cylinder so that the pressure in the starved area 23 is fixed, and the physical blowing agent is continuously brought into contact with the molten resin. This stabilizes the amount of physical blowing agent dissolved (permeated) in the molten resin, which is determined by the temperature and pressure. In addition, since the physical blowing agent of the present embodiment is always in contact with the molten resin, a necessary and sufficient amount of the physical blowing agent can be permeated into the molten resin. Thus, the foamed molded article produced in the present embodiment has fine foam cells even when a low-pressure physical blowing agent is used, as compared with a conventional molding method using a physical blowing agent.

In addition, in the manufacturing method of the present embodiment, since it is not necessary to control the introduction amount, the introduction time, and the like of the physical foaming agent, a drive valve such as a check valve or an electromagnetic valve is not necessary, and further, a control mechanism for controlling them is not necessary, and the apparatus cost is reduced. Further, the physical blowing agent used in the present embodiment is also lower in pressure than a conventional physical blowing agent, and therefore the burden on the apparatus is also small.

In the present embodiment, in the production of a foam molded body in which the injection molding cycle is continuously performed, the starved region 23 is kept at a constant pressure. That is, in order to replenish the physical foaming agent consumed in the plasticizing cylinder, the entire steps of the method for producing a foamed molded article are performed while continuously supplying the physical foaming agent at a fixed pressure. In the present embodiment, for example, in the case of injection molding in which a plurality of injections are continuously performed, a subsequent injection amount of molten resin is prepared in the plasticizing cylinder during the injection step, the cooling step of the molded body, and the removing step of the molded body, and the subsequent injection amount of molten resin is pressurized at a fixed pressure by the physical foaming agent. That is, in injection molding in which multiple injections are continuously performed, 1 cycle of injection molding including a plasticization measurement step, an injection step, a cooling step of a molded body, a take-out step, and the like is performed in a state where a molten resin in a plasticizing cylinder is always in contact with a physical foaming agent at a fixed pressure, that is, in a state where the molten resin in the plasticizing cylinder is always pressurized at a fixed pressure by the physical foaming agent. Similarly, in the case of continuous molding such as extrusion molding, molding is performed in a state where the molten resin in the plasticizing cylinder is always in contact with a physical blowing agent at a fixed pressure, that is, in a state where the molten resin in the plasticizing cylinder is always pressurized by the physical blowing agent at a fixed pressure.

(5) Foam molding

Next, the molten resin in contact with the physical foaming agent is molded into a foamed molded article (step S5 of fig. 1). The plasticizing cylinder 210 used in the present embodiment has a recompression zone 24, which is disposed downstream of the starvation zone 23, is adjacent to the starvation zone 23, and raises the pressure of the compressed molten resin. First, the molten resin in the starvation zone 23 is made to flow to the recompression zone 24 by the rotation of the plasticizing screw 20. The molten resin containing the physical blowing agent is pressure-regulated in the recompression zone 24, extruded forward of the plasticizing screw 20, and measured. At this time, the internal pressure of the molten resin extruded forward of the plasticizing screw 20 is controlled by a hydraulic motor or an electric motor (not shown) connected to the rear of the plasticizing screw 20 as a screw back pressure. In the present embodiment, in order to uniformly compatibilize the physical blowing agent without separating it from the molten resin and stabilize the resin density, it is preferable to control the internal pressure of the molten resin extruded forward of the plasticizing screw 20 (i.e., the screw back pressure) to be about 1 to 6MPa higher than the pressure of the starvation zone 23 which is kept constant. In the present embodiment, a check ring 50 is provided at the tip of the screw 20 so that the compressed resin in front of the screw 20 does not flow backward to the upstream side. Thus, the pressure in starvation zone 23 does not affect the resin pressure ahead of screw 20 when measured.

The method for molding the foamed molded article is not particularly limited, and the molded article can be molded by, for example, injection foam molding, extrusion foam molding, foam blow molding, or the like. In the present embodiment, the measured molten resin is injected and filled from the plasticizing cylinder 210 shown in fig. 2 into a cavity (not shown) in the mold, and injection foam molding is performed. As the injection foam molding, a short shot method of filling a cavity with a molten resin having a filling capacity of 75% to 95% of the cavity volume of the mold and filling the cavity while expanding bubbles may be used, or a core-removing method of expanding and foaming the cavity volume after filling the molten resin having a filling amount of 100% of the cavity volume of the mold may be used. Since the resulting foamed molded article has cells inside, shrinkage of the thermoplastic resin during cooling is suppressed, and a molded article having a low specific gravity is obtained with reduced sink marks and warpage. The shape of the foamed molded article is not particularly limited. The sheet-like or cylindrical shape may be obtained by extrusion molding, or the complicated shape may be obtained by injection molding.

In the method for producing a foamed molded article described above, since it is not necessary to control the amount of introduction, the introduction time, and the like of the physical foaming agent into the molten resin, a complicated control device can be omitted or simplified, and the device cost can be reduced. In the method for producing a foamed molded article of the present embodiment, the molten resin in a starved state is brought into contact with the physical foaming agent at a constant pressure in the starved area 23 while the starved area 23 is kept at the constant pressure. This can stabilize the amount of physical blowing agent dissolved (permeated) in the molten resin by a simple mechanism.

(6) Forming of circuit patterns

Next, a circuit pattern is formed on the surface of the obtained foam molded product (step S6 in fig. 1). The method for forming the circuit pattern on the foam molded product is not particularly limited, and a general method, for example, a plating film may be used. For example, a method of forming a plating film on the surface of a foam molded body, patterning the formed plating film with a photoresist, and removing the plating film except for the circuit pattern by etching is exemplified. In addition, a method of irradiating a portion of the foamed molded article where a circuit pattern is to be formed with laser light to roughen the surface or to provide a functional group thereto, and forming a plating film only on the laser-irradiated portion may be used. The circuit pattern may be formed by the methods disclosed in japanese patent application laid-open nos. 2017-31441 and 2017-160518.

A method for forming a circuit pattern used in the present embodiment will be described below with reference to fig. 3 and 4. First, the catalyst activity suppression layer 61 is formed on the surface of the foamed molded article 60 (step S11 in fig. 3 and fig. 4 (a)). Next, a part of the surface of the foamed molded article on which the catalyst activity suppression layer 61 is formed, that is, a part where a circuit pattern is formed, is heated or irradiated with light (step S12 of fig. 3). In this embodiment, laser drawing is performed on a portion where a circuit pattern is formed. The laser-irradiated portion 60a is heated, and the catalyst activity suppression layer 61 of the heated portion is removed (fig. 4 (b)). An electroless plating catalyst is applied to the surface of the laser-drawn foam molding 60 (step S13 in fig. 3), and then the foam molding is brought into contact with the electroless plating solution (step S14 in fig. 3). In this method, the catalyst activity suppressing layer 61 suppresses (hinders) the catalyst activity of the electroless plating catalyst imparted thereto. Therefore, the generation of the electroless plating film is suppressed on the catalytic activity suppression layer 61. On the other hand, the laser drawing portion 60a generates the electroless plating film 62 due to the removal of the catalyst activity suppressing layer 61. By the above-described method, a molded circuit member 600 in which a circuit pattern formed of the electroless plating film 62 is formed on the surface of the foam molded body 60 is obtained (fig. 4 (c)).

The catalyst activity suppression layer preferably contains a polymer having at least one of an amide group and an amino group (hereinafter, appropriately referred to as "amide group-containing/amino group-containing polymer"), for example. The amide group-containing/amino group-containing polymer functions as a catalyst activity inhibitor that inhibits (hinders) or reduces the catalyst activity of the electroless plating catalyst. The mechanism by which the amide group-containing/amino group-containing polymer suppresses the catalytic activity of the electroless plating catalyst is not yet determined, and it is presumed that the amide group and the amino group are adsorbed, coordinated, reacted, and the like with the electroless plating catalyst, and thus the electroless plating catalyst cannot function as a catalyst.

The amide group-containing/amino group-containing polymer may be any optional one, and from the viewpoint of suppressing the catalytic activity of the electroless plating catalyst, a polymer having an amide group is preferable, and a branched polymer having a side chain is preferable. In the branched polymer, the side chain preferably contains at least one of an amide group and an amino group, and more preferably contains an amide group. The branched polymer is preferably a dendrimer. Dendrimers are polymers composed of a molecular structure of frequently regularly repeating branched chains, and are classified into dendrimers and hyperbranched polymers. The dendrimer is a spherical polymer having a structure of a complete tree-like branch chain with a strict regularity centered on a molecule serving as a core and a diameter of several nm, and the hyperbranched polymer is a polymer having incomplete tree-like branch chains, unlike the dendrimer having a complete tree-like structure. Among dendrimers, hyperbranched polymers are relatively easy to synthesize and inexpensive, and are therefore preferred as the branched polymer of the present embodiment.

The laser, the electroless plating catalyst and the electroless plating solution used in the laser drawing are not particularly limited, and a general-purpose substance can be appropriately selected and used. In the formation of the circuit pattern, another type of electroless plating film or electroplating film may be further laminated on the electroless plating film. The plating film 62 for forming the circuit pattern may be formed in a planar shape on only one surface of the foamed molded body 60, or may be formed three-dimensionally along a plurality of surfaces of the foamed molded body 60 or a three-dimensional surface including a spherical surface. When the plating film 62 is formed three-dimensionally along a plurality of surfaces of the foam molded body 60 or along a three-dimensional surface including a spherical surface or the like, the plating film 62 functions as a three-dimensional electric circuit, and the molded circuit component 600 having the plating film 62 of such a predetermined pattern functions as a three-dimensional circuit molded component (MID).

Further, as shown in fig. 4(c), the molded circuit member 600 manufactured by the present embodiment described above has the catalyst activity suppression layer 61, but the present embodiment is not limited thereto. The production method of the present embodiment may further include a step of removing the catalyst activity suppressing layer 61 from the surface of the foamed molded article 60. As a method for removing the catalyst activity suppressing layer 61 from the molded foam 60, there is a method in which the molded foam 60 is washed with a washing liquid to dissolve the amide group/amino group-containing polymer in the washing liquid and remove the amide group/amino group-containing polymer. The washing liquid is not particularly limited as long as it dissolves the amide group-containing/amino group-containing polymer and does not change the properties of the foamed molded article 60, and it can be appropriately selected according to the material of the foamed molded article 60 and the kind of the amide group-containing/amino group-containing polymer.

< molded circuit component >

The molded circuit member 600 of the present embodiment includes a base material as the foamed molded body 60 containing the thermoplastic resin and a circuit pattern formed on the base material, and is lightweight. The present inventors have also found that a molded circuit component having high heat resistance can be produced by the production method of the present embodiment. The heat-resistant temperature of the special engineering plastic used in the manufacturing method of the embodiment is as high as 150 ℃. However, the heat resistance of the foamed molded article is generally lower than that of a solid molded article (non-foamed molded article), and sufficient heat resistance cannot be obtained even when a special engineering plastic is used as the thermoplastic resin in the foamed molded article produced using the conventional high-pressure physical foaming agent. In a conventional molded circuit part using a foamed molded article of a special engineering plastic, there are disadvantages such as expansion of foam cells and increase in thickness of the molded article if the molded article is passed through a reflow furnace. On the other hand, when the molded circuit member obtained in the present embodiment is heated and the surface temperature of the molded circuit member is maintained at 240 to 260 ℃ for 5 minutes, the rate of change in the thickness of the molded circuit member due to heating is-2 to 2%, preferably-1 to 1%. In addition, when the surface temperature of the molded circuit member obtained in the present embodiment is maintained at 200 to 260 ℃ for 3 to 10 minutes, for example, the rate of change in the thickness of the molded circuit member due to heating is-2 to 2%, preferably-1 to 1%. Such a molded circuit component having high heat resistance has a small change in shape even when it is passed through a reflow furnace for lead-free solder, and is less likely to cause swelling or the like.

Here, the "rate of change in thickness of the molded circuit member due to heating" is defined by the following equation. The molded circuit component may be heated in a reflow furnace, for example.

(Da－Db)/Db×100(％)

Db: thickness of molded circuit parts before heating

Da: thickness of molded circuit parts after heating

It is presumed that the high heat resistance of the molded circuit component of the present embodiment is brought about by using a special engineering plastic as the thermoplastic resin and setting the fixed pressure of the physical blowing agent in contact with the starved molten resin to a specific range of, for example, 0.5MPa to 12 MPa. In conventional foam molding using a supercritical fluid or the like, a high-pressure physical foaming agent having an average pressure of 15 to 20MPa is used. The production method of the present embodiment is different from the conventional foam molding in that a physical blowing agent having a relatively low pressure and a fixed pressure is brought into contact with a molten resin. The present inventors have found that the heat resistance of a foamed molded article is improved by setting the fixing pressure of the physical blowing agent to, for example, 12MPa or less, preferably 10MPa or less, more preferably 8MPa or less, and still more preferably 6MPa or less. Further, by reducing the fixing pressure of the physical foaming agent, appearance defects (spin marks) can be improved. The lower limit of the fixed pressure of the physical blowing agent is 0.5MPa or more, preferably 1MPa or more, and more preferably 2MPa or more, from the viewpoint of allowing the physical blowing agent in an amount necessary for foaming to permeate into the molten resin.

The mechanism by which the molded circuit component of the present embodiment has high heat resistance is not clear, and there is a possibility that: the molded circuit component of the present embodiment is different from a conventional foamed molded article in the fine structural change, for example, a very microscopic structural change, by the combination of a specific type of thermoplastic resin (a special engineering plastic) and a fixed pressure (for example, 0.5MPa to 12MPa) of a physical foaming agent in a specific range. Further, it is presumed that the residual foaming agent in the foamed molded article expands by heating, and adversely affects the heat resistance of the foamed molded article. Therefore, it is considered that the reason why the foamed molded article of the present embodiment has high heat resistance is simply because the amount of the residual foaming agent in the foamed molded article is small. However, according to the studies of the inventors, it was found that even if the residual foaming agent is degassed to some extent from the conventional foamed molded article by, for example, annealing treatment or the like, the same heat resistance as that of the foamed molded article of the present embodiment cannot be obtained, and swelling or the like is generated by heating. Therefore, it is presumed that the amount of the residual blowing agent is not a factor of the high heat resistance of the foamed molded article of the present embodiment. The above-described examination is merely an assumption by the inventors based on a phenomenon observed at present, and is not intended to limit the scope of the present invention at all.

The fixed pressure of the physical foaming agent in the present embodiment is, for example, 0.5MPa to 12MPa, and there is a more preferable range depending on the kind of the special engineering plastic. For example, when the special engineering plastic is polyphenylene sulfide (PPS), the fixing pressure of the physical foaming agent is preferably 2MPa to 12MPa, more preferably 2MPa to 10MPa, and still more preferably 2MPa to 8 MPa. When the special engineering plastic is a Liquid Crystal Polymer (LCP), the fixing pressure of the physical foaming agent is preferably 1MPa to 6 MPa. When the type of the special engineering plastic and the fixing pressure of the physical foaming agent are in the above-mentioned combination, a foamed molded article having a better foamability and a higher heat resistance can be obtained, and further, the occurrence of swirl marks can be suppressed.

The average cell diameter of the foamed cells contained in the molded circuit component produced in the present embodiment is preferably 100 μm or less, and more preferably 50 μm or less. When the average cell diameter of the cells to be foamed is within the above range, the side walls of the cells are small, and therefore expansion is difficult during heating, and as a result, the heat resistance of the foamed molded article is further improved. The average cell diameter of the foamed cells can be determined by, for example, SEM photograph image analysis of a cross section of the foamed molded article.

In the foamed molded article of the molded circuit component produced in the present embodiment, the thickness of the foamed part in which the foamed cells are formed is preferably 0.5mm or more, more preferably 1mm or more, and still more preferably 2mm or more. When the thickness is within the above range, a skin-like layer having a sufficient thickness can be formed in the molded article. The expansion of the foam cells during heating of the molded circuit component can be suppressed by the skin layer, and therefore the heat resistance of the molded circuit component is further improved. In particular, when LCP is used as a special engineering plastic, it is difficult for encapsulated gas containing a physical foaming agent to be released from a foamed molded article of LCP. By increasing the thickness of the foamed part, expansion of the foamed cells due to expansion of the encapsulated gas is suppressed, and the heat resistance of the molded circuit component using LCP is further improved. In the foam molded body of the molded circuit member produced in the present embodiment, the thickness of the foamed part in which the foamed cells are formed may be 3mm or less, 2mm or less, or 1mm or less. Although the smaller the thickness of the foamed part, the greater the rate of change in the thickness of the molded circuit member by heating tends to be, the molded circuit member produced by the production method of the present embodiment has high heat resistance, and therefore, the rate of change in the thickness of the molded circuit member by heating can be suppressed to-2% to 2%, preferably-1% to 1%, even in a foamed part having a thickness within the above range.

In the present embodiment, the molded foam may be further annealed before the circuit pattern is formed. By heating the foamed molded article in the annealing treatment, the entrapped gas containing the physical foaming agent can be degassed from the foamed molded article. This suppresses expansion of the foam cells due to expansion of the encapsulated gas, thereby further improving the heat resistance of the molded circuit component.

[ second embodiment ]

< Circuit component >

In this embodiment, a circuit member 700 shown in fig. 5(a), (b), and 6 will be described. The circuit member 700 of the present embodiment includes a base material 10 which is a foamed molded body containing a thermoplastic resin, and a circuit pattern 70 formed on the base material 10, and is lightweight. Further, the circuit member 700 has: a substrate 10 having a mounting surface 10a and a back surface 10b opposite to the mounting surface 10a, a circuit pattern 70 formed on the surface of the substrate 10 including the mounting surface 10a, and a mounting member 30 mounted on the mounting surface 10a of the substrate 10 and electrically connected to the circuit pattern 70, which is a plate-like foamed molded article having a density reduction rate of preferably 0.5% to 10%.

The substrate 10 contains a thermoplastic resin, preferably a thermoplastic resin and an insulating heat conductive filler, and has foamed cells 11 inside.

The thermoplastic resin is preferably a high-melting-point thermoplastic resin having heat resistance and solder reflow resistance. For example, aromatic polyamides such as 6T nylon (6TPA), 9T nylon (9TPA), 10T nylon (10TPA), 12T nylon (12TPA), MXD6 nylon (MXDPA), and alloy materials thereof, polyphenylene sulfide (PPS), Liquid Crystal Polymer (LCP), polyether ether ketone (PEEK), polyether imide (PEI), and polyphenylene sulfone (PPSU) can be used. Among these, polyphenylene sulfide is preferred as the thermoplastic resin of the present embodiment because it is inexpensive among so-called super engineering plastics (special engineering plastics). These thermoplastic resins may be used alone, or 2 or more kinds may be used in combination. In the present embodiment, the mounting member 30 is mounted by soldering. Therefore, the thermoplastic resin used for the base material 10 preferably has a melting point of 260 ℃ or higher, more preferably 290 ℃ or higher so as to be solderable. The case of using low-temperature solder for mounting the mounting member 30 is not limited to the above.

The insulating heat conductive filler is a filler having a heat conductivity of 1W/m.K or more, except for a conductive heat releasing material such as carbon. Examples of the insulating heat conductive filler include ceramic powders such as alumina, silica, magnesia, magnesium hydroxide, boron nitride, and aluminum nitride, which are high heat conductive inorganic powders. In order to increase the contact ratio between the fillers and improve the thermal conductivity, a rod-like filler such as wollastonite or a plate-like filler such as talc or boron nitride may be mixed. The insulating heat conductive filler is contained in the base material 10 by, for example, 10 to 90 wt%, preferably 30 to 80 wt%. If the amount of the insulating heat conductive filler is within the above range, the circuit component 700 of the present embodiment can obtain sufficient heat dissipation.

Further, in order to control the strength, the substrate 10 may contain a rod-like or needle-like filler such as glass fiber or calcium titanate. The base material 10 may contain various general-purpose additives added to the resin molded body as necessary.

The base material 10 is a foamed molded article having a density reduction ratio of preferably 0.5% to 10%. The density reduction rate of the substrate 10 is more preferably 1% to 7%, and still more preferably 4% to 6%. When the density reduction rate of the substrate 10 is set within the above range, the moldability of the substrate 10 is improved, and the circuit member 700 can obtain sufficient heat dissipation. Here, the density decrease rate of the foamed molded article is a ratio of a difference between the density of the solid molded article and the density of the foamed molded article to the density of a non-foamed molded article (solid molded article) molded using the same material as the foamed molded article. The foamed molded article contains foamed cells (cells), and therefore has a smaller specific gravity than a solid molded article. For example, a density reduction rate of the foamed molded article of 5% means that the density (95%) of the foamed molded article is reduced by 5% with respect to the density (100%) of the solid molded article.

The circuit pattern 70 is formed on the resin base 10 which is an insulator, and is preferably formed by electroless plating. Therefore, the circuit pattern 70 may include electroless nickel-phosphorus film, electroless copper film, electroless nickel film, and other electroless plated films, and preferably includes electroless nickel-phosphorus film. The circuit pattern 70 may be formed by further laminating another type of electroless plating film or electroplating film on the electroless plating film on the resin substrate 10. The resistance of the circuit pattern 70 can be reduced by increasing the total thickness of the plating film. The circuit pattern 70 preferably includes an electroless copper plating film, an electrolytic nickel plating film, or the like, from the viewpoint of reducing resistance. In addition, a plating film of gold, silver, tin, or the like may be formed on the outermost surface of the circuit pattern 70 in order to improve the solder wettability of the plating film.

When a gold plating film is provided on the outermost surface of the circuit pattern 70, the wettability of the solder is improved and the circuit pattern can be prevented from being corroded. However, if the gold plating film is provided on the entire outermost surface of the circuit pattern 70, the cost increases. In order to suppress the cost increase and prevent the corrosion of the circuit pattern 70, a portion of the mounting surface 10a other than the mounting portion 12 of the soldered mounting member 30 may be covered with a resist, and a gold plating film may be formed only on the outermost surface of the circuit pattern formed on the mounting portion 12. In the mounting portion 12, the gold plating film improves the wettability of the solder, suppresses the corrosion of the circuit pattern, and suppresses the corrosion of the circuit pattern 70 in the portion other than the mounting portion 12 by the inexpensive resist.

The mounting component 30 is electrically connected to the circuit pattern 70 by solder 31, and generates heat by energization to serve as a heat source. Examples of the mounting member 30 include an LED (light emitting diode), a power module, an IC (integrated circuit), and a thermal resistor. In the present embodiment, an LED is used as the mounting member 30. The mounting member 30 is mounted on the mounting surface 10a of the base 10. The circuit pattern 70 is formed on the surface of the base material 10 including the mounting surface 10a so as to be electrically connected to the mounting member 30.

In the portion (mounting portion 12) of the base material 10 where the mounting member 30 is mounted, the distance from the mounting surface 10a to the rear surface 10b (the thickness d of the mounting portion 12) is preferably 0.1mm or more, and more preferably more than 0.5 mm. Here, the distance from the mounting surface 10a to the rear surface 10b (the thickness d of the mounting portion 12) is a distance in the direction of the perpendicular m to the mounting surface 10a from the mounting surface 10a to the rear surface 10b of the mounting portion 12. When the thickness d of the mounting portion 12 is not constant, the thickness d preferably varies within the above range. In the present embodiment, the substrate 10 is a plate-like body, and the back surface 10b is a surface opposite to the mounting surface 10 a. Since the substrate 10 of the present embodiment is a plate-like body having a constant thickness, the thickness d is also the thickness of the substrate 10.

The thickness d is preferably small in order to dissipate heat generated by the mounting member 30 from the rear surface 10 b. However, if the thickness d of the mounting portion 12 is too thin, the flowability of the resin in the mounting portion 12 is reduced when the base material 10 is molded, and as a result, moldability is reduced. In addition, the mechanical strength of the substrate 10 is reduced, and the substrate 10 alone is difficult to be self-supporting. When the substrate 10 cannot be self-supported, for example, a support member such as a metal plate for supporting the substrate 10 must be added to the back surface 10b of the substrate 10, which increases the cost. In the present embodiment, since the mounting portion 12 has an appropriate thickness, it is possible to prevent the moldability and mechanical strength of the base material 10 from being reduced, and since a support member or the like for the base material 10 is not required, it is possible to prevent an increase in cost. When importance is attached to the mechanical strength of the base material 10, the thickness d is preferably 0.6mm or more. The upper limit of the thickness d is not particularly limited, and may be appropriately determined according to the use of the circuit member 700. From the viewpoint of cost, the thickness d is, for example, 2.5mm or less.

In addition, generally, if the thickness of the foam molded article is 0.2mm or less or 0.5mm or less, the foam molded article is mainly composed of a skin layer, and the core layer is hardly formed inside, and as a result, it is difficult to form foam cells inside. If the thickness d of the mounting portion 12 is 0.2mm or less or 0.5mm or less, almost no foam cells are present inside, and thus the heat radiation property to the back surface 10b is improved. On the other hand, if the thickness d of the mounting portion 12 exceeds 0.5mm, the foam cells 11 may be present inside the mounting portion 12, and thus the heat dissipation tends to be reduced. However, since the substrate 10 of the present embodiment contains the insulating heat conductive filler, it is possible to ensure a certain level of heat radiation property, and it is also advantageous to improve mechanical strength as described above.

As described below, the circuit component 700 of the present embodiment described above can achieve both mass productivity and heat dissipation. The substrate 10 is a foamed molded body. Therefore, even in the case of a thermoplastic resin containing an insulating heat conductive filler, the fluidity of the molten resin is improved by the foaming agent contained during molding. Further, the foaming pressure improves the transferability of the mold, and the substrate 10 obtains sufficient dimensional accuracy. In this way, since the moldability of the base material 10 is improved, molding is performed without increasing the holding pressure or the clamping pressure, and the generation of burrs is suppressed. This can suppress the manufacturing cost of the circuit member 700 and improve mass productivity. On the other hand, since the foamed molded article contains foamed cells, the heat insulating property tends to be improved and the heat releasing property tends to be lowered. However, in the substrate 10 of the present embodiment, the density decrease rate is determined to be within the relatively low range, and as shown in fig. 6, the generation of bubbles in the skin layer 13 can be suppressed. The foamed cells 11 are present primarily within the core layer 14. Therefore, the surface of the substrate 10 (mounting surface 10a) to which the mounting member 30 serving as a heat source is mounted has little influence on the foam cells 11, and the insulating heat conductive filler is oriented in the resin flow direction, thereby obtaining sufficient heat dissipation properties.

Further, the base material 10 of the present embodiment is a foam molded body, and has solder reflow resistance. Since the foamed molded article contains foam cells, the surface is likely to bulge when solder is reflowed. However, by setting the density decrease rate of the base material 10 within the above relatively low range, the density of the foam cells 11 in the base material 10 can be made relatively low. Further, the amount of the foaming agent remaining in the resin can be reduced. This presumably improves the solder reflow resistance of the substrate 10. Further, in the base material 10 of the present embodiment, the amount of the foaming agent to be used can be reduced by setting the density decrease rate to be within the above-described relatively low range. For example, in the case of using a physical blowing agent as the blowing agent, a physical blowing agent having a relatively low pressure may be used. This makes it difficult for the circuit pattern 70 to have a poor appearance during foam molding, and therefore, the circuit pattern 70 is easily formed on the surface. Further, in the circuit component 700 of the present embodiment, since the base material 10 has sufficient heat radiation performance, a metal heat radiation member may not be provided. Thereby enabling cost reduction.

In the present embodiment, as shown in fig. 5(a), (b) and 6, the circuit pattern 70 is formed only on one surface (mounting surface 10a) of the base 10 of the plate-like body, but the present embodiment is not limited thereto. The substrate 10 is not limited to a plate-like body, and may have any shape according to the use of the circuit member 700. The circuit pattern 70 may be formed three-dimensionally along a three-dimensional surface including a spherical surface or the like, continuously over a plurality of surfaces of the base material 10. When the circuit pattern 70 is formed three-dimensionally along a three-dimensional surface including a spherical surface or the like over a plurality of surfaces of the base material 10, the circuit member 700 functions as a three-dimensional molded circuit member.

In the circuit component 700 of the present embodiment, when the thermoplastic resin is a special engineering plastic, the heat resistance thereof may be equivalent to the heat resistance of the molded circuit component 600 (see fig. 4(c)) of the first embodiment. That is, when the circuit member 700 is heated and the surface temperature of the circuit member 700 is maintained at 240 to 260 ℃ for 5 minutes, the rate of change in the thickness of the circuit member 700 due to heating may be-2% to 2%, or preferably-1% to 1%. In the circuit member 700 obtained in the present embodiment, when the surface temperature of the circuit member 700 is maintained at 200 to 260 ℃ for 3 to 10 minutes, for example, the rate of change in the thickness of the circuit member 700 due to heating may be-2 to 2%, and preferably-1 to 1%. The circuit component having such high heat resistance has a small change in shape even when it passes through a reflow furnace for lead-free solder, and is less likely to bulge.

< method for manufacturing circuit component >

A method of manufacturing the circuit member 700 will be described. First, a thermoplastic resin preferably containing an insulating heat conductive filler is foam-molded to obtain a foam-molded body (substrate 10) having a density reduction ratio of preferably 0.5% to 10%. The base material 10 is preferably formed by foaming using a physical foaming agent such as carbon dioxide or nitrogen. The foaming agent includes a chemical foaming agent and a physical foaming agent, but the chemical foaming agent has a low decomposition temperature and thus it is difficult to foam a resin material having a high melting point. The base material 10 is preferably made of a resin having a high melting point and high heat resistance. If a physical foaming agent is used, the base material 10 can be foam-molded using a high-melting resin. As a molding method using a physical blowing agent, MuCell (registered trademark) using a supercritical fluid, a low-pressure foaming molding method which does not require high-pressure equipment and which is proposed by the present inventors (for example, described in WO 2017/007032) can be used.

When the base material 10 is molded by the low-pressure foam molding method described in WO2017/007032, the density reduction rate of the foam molded article can be adjusted by adjusting the pressure of the physical foaming agent introduced into the plasticizing cylinder of the foam injection molding machine, the filling rate of the resin in the mold, and the like. In the low-pressure foam molding method, the pressure of the physical foaming agent introduced into the plasticizing cylinder is, for example, 10MPa or less, preferably 6MPa or less, and more preferably 2MPa or less.

The base material 10 can be produced by the same production method as the foamed molded article 60 of the first embodiment, using the production apparatus (injection molding apparatus) 1000 shown in fig. 2 used in the first embodiment.

Next, a circuit pattern 70 is formed on the surface of the base 10 including the mounting surface 10 a. The method for forming the circuit pattern 70 is not particularly limited, and a general method can be used. Examples thereof include: a method of forming a plating film on the mounting surface 10a entirely, patterning the plating film with a resist, and removing the plating film except for the circuit pattern by etching, a method of irradiating a laser beam to roughen the substrate at a portion where the circuit pattern is to be formed, and forming a plating film only at the laser-irradiated portion, and the like. The circuit pattern 70 may be formed by the same method as that of the circuit pattern of the first embodiment.

In the present embodiment, the circuit pattern 70 is formed by the method described below. First, a catalytic activity suppression layer is formed on the surface of the substrate 10. Next, laser drawing is performed on the electroless plated film-formed portion of the mounting surface 10a of the base 10 on which the catalytic activity suppressing layer is formed, that is, the portion on which the circuit pattern 70 is formed. Thereby, the laser drawing portion 15 is formed on the mounting surface 10a (fig. 7(a) and (b)). The laser-mapped surface of the substrate 10 is given an electroless plating catalyst and, subsequently, is brought into contact with an electroless plating solution. The catalyst activity inhibiting layer inhibits (hinders) the catalyst activity imparted to the electroless plating catalyst thereon. Therefore, the generation of the electroless plating film is suppressed on the catalyst activity suppression layer. On the other hand, the laser drawing portion 15 generates an electroless plating film due to the removal of the catalyst activity suppressing layer. Thereby, in the laser drawing portion 15, a circuit pattern 70 is formed by electroless plating (fig. 8(a) and (b)).

The catalyst activity suppressing layer may be formed using a resin (catalyst deactivator) that suppresses the catalytic activity. As the catalyst deactivator, a polymer having an amide group and a dithiocarbamate group in a side chain is preferable. It is presumed that the amide group and the dithiocarbamate group of the side chain act on the metal ion as the electroless plating catalyst to suppress the exertion of the catalytic ability. The catalyst deactivator is preferably a dendrimer such as a dendrimer or a hyperbranched polymer. As the catalyst deactivator, for example, a polymer disclosed in Japanese patent laid-open publication No. 2017-160518 can be used, and a suppression layer can be formed on the surface of the substrate by the method disclosed in the same patent publication.

The laser and the laser drawing method used in the laser drawing are not particularly limited, and a general laser and a laser drawing method can be appropriately selected and used. In the laser drawing portion 15, as shown in fig. 7(b), the surface of the substrate 10 may be roughened while the catalyst activity suppression layer (not shown in the figure) is removed. Thereby, the electroless plating catalyst is easily adsorbed to the laser drawing portion 15.

The electroless plating catalyst is not particularly limited, and a general-purpose material can be appropriately selected and used. Further, as the electroless plating catalyst, for example, a plating catalyst solution containing a metal salt such as palladium chloride disclosed in japanese patent application laid-open No. 2017-036486 can be used. In the case where a plating catalyst solution containing a metal salt is used as an electroless plating catalyst, a pretreatment liquid that promotes adsorption of an electroless plating catalyst may be applied to a substrate before applying the plating catalyst solution to the substrate. As the pretreatment liquid, for example, an aqueous solution containing a nitrogen-containing polymer such as polyethyleneimine can be used.

The electroless plating solution and the electroless plating method are not particularly limited, and a general electroless plating solution and an electroless plating method can be appropriately selected and used. The electroless plating solution contains a reducing agent such as sodium hypophosphite or formalin, for example. As the electroless plating solution, an electroless nickel-phosphorus plating solution, an electroless copper plating solution, an electroless palladium plating solution, and the like can be used, and among them, sodium hypophosphite containing an electroless plating catalyst (metal ion) and having a good reduction effect is preferably used as a reducing agent, and the plating solution is a stable electroless nickel plating solution (electroless nickel-phosphorus plating solution). In the formation of the circuit pattern 70, another type of electroless plating film or electroplating film may be further laminated on the electroless plating film.

As described above, in order to suppress the increase in cost and prevent corrosion of the circuit pattern 70, the mounting surface 10a may be covered with a resist except for the mounting portion 12 of the soldered mounting component 30, and a gold plating film may be formed only on the outermost surface of the circuit pattern 70 formed on the mounting portion 12. The circuit pattern of such a manner can be formed by, for example, the following method. First, a solder resist (for example, manufactured by sun ink corporation) is applied to the entire surface of the substrate 10 on which the circuit pattern is formed, excluding the gold plating film on the outermost surface, including the mounting surface 10a, to form a resist layer. Next, the resist layer on the mounting surface 10a of the mounting portion 12 is removed by laser light to form an opening, and the circuit pattern is exposed in the opening. Further, a gold plating film is formed only on the outermost surface of the circuit pattern exposed in the opening.

After the circuit pattern 70 is formed on the substrate 10, the mounting member 30 is mounted on the mounting surface 10a of the substrate 10 and electrically connected to the circuit pattern 70. This results in the circuit component 700 of the present embodiment. The mounting method is not particularly limited, and a general method can be used, and for example, the mounting member 30 can be soldered to the base material 10 by a solder reflow method in which the base material 10 on which the mounting member 30 is disposed is passed through a high-temperature reflow furnace, or a laser soldering method (spot mounting) in which the interface between the base material 10 and the mounting member 30 is irradiated with a laser beam to perform soldering.

[ modification 1]

Next, a modified example 1 of the second embodiment shown in fig. 9 will be described. The substrate 10 of the circuit member 700 shown in fig. 5 is a plate-like body having a constant thickness, but the present embodiment is not limited thereto. For example, as in the circuit component 400 of the present modification shown in fig. 9, the recess 45 defined by the side wall 45a and the bottom surface 45b may be provided on the back surface 40b of the base 40. The mounting member 30 is mounted on the mounting surface 40a corresponding to the bottom surface 45 b. The circuit component 400 of the present modification has the same configuration as the circuit component 700 shown in fig. 5, except for the recess 45.

In the present modification, the recess 45 is provided in the back surface 40b, and the thickness d1 of the mounting portion 42 provided with the mounting member 30 is reduced, whereby the core layer in the mounting portion 42 is made thin. This improves the heat conductivity in the thickness direction of the mounting portion 42, and facilitates the release of heat generated by the mounting member 30 to the rear surface 40 b. This can further improve the heat dissipation of the circuit component 400.

As a method of reducing the thickness d1 of the mounting portion 42, a method of providing a recess in the mounting surface 40a may be considered. However, if the mounting surface 40a is provided with irregularities, there is a possibility that it is difficult to form the circuit pattern 70. For example, in the case of forming a pattern of an electroless plating film using the above-described catalytic activity suppressing layer, there is a case where the contrast (contrast) of the plating film is hard to adhere to the surface having irregularities. In the present modification, by providing the rear surface 40b with the irregularities, the heat dissipation performance of the circuit member 400 can be improved without adversely affecting the formation of the circuit pattern 70 on the mounting surface 40 a.

The distance d1 from the mounting surface 40a to the bottom surface 45b is preferably 0.1mm to 1.5mm, for example. Here, the distance d1 from the mounting surface 40a to the bottom surface 45b is a distance in the perpendicular direction of the mounting surface 40a from the mounting surface 40a to the bottom surface 45 b. When the distance d1 is not constant, the distance d1 preferably varies within the above range. By setting the distance d1 within the above range, the moldability and mechanical strength of the base material 40 can be prevented from being lowered, and the heat dissipation performance of the circuit member 400 can be improved.

In the present modification, as shown in fig. 9, 1 mounting member 30 is mounted on the mounting surface 40a corresponding to the bottom surface 45b of 1 recess 45. However, the present embodiment is not limited thereto. For example, a plurality of mounting members 30 may be mounted on mounting surface 40a corresponding to bottom surface 45b of 1 recess 45. The area of the bottom surface 45b may be larger or smaller than the area of the bottom surface of the mounting member 30, or the area of the bottom surface 45b may be substantially the same as the area of the bottom surface of the mounting member 30.

The area of the bottom surface 45b of each mounting member 30 arranged on the mounting surface 40a corresponding to the bottom surface 45b is, for example, 4cm²Hereinafter, preferably 0.4cm²～4cm². The larger the area of the bottom surface 45b, the higher the heat radiation property, but the moldability and mechanical strength of the recessed portion 45 are lowered. By setting the area of the bottom surface 45b within the above range, heat radiation property, moldability, and mechanical strength can be both satisfied.

The thickness d2 of the portion of the base material 40 other than the mounting portion 42 is, for example, 0.6mm to 2.5mm from the viewpoint of mechanical strength and cost.

The recess 45 may be formed simultaneously with the molding of the substrate 40. For example, the base material 40 of the present modification can be molded using a mold having a convex portion corresponding to the concave portion 45 in a mold cavity.

[ modification 2]

Next, a modified example 2 of the second embodiment shown in fig. 10 will be described. As shown in fig. 10, in a circuit component 500 of the present modification, a recess 55 defined by a side wall 55a and a bottom surface 55b is provided on a back surface 50b of a base material 51. Further, a through hole 56 is formed from the mounting surface 50a of the mounting portion 52 to which the mounting member 30 is mounted toward the bottom surface 55b, and an electroless plating film 71 is formed on the inner wall of the through hole 56. The through-hole 56 of the present modification is filled with an electroless plating film 71. The electroless plated film 71 of the through hole 56 is connected to the mounting component 30 via the circuit pattern 70 and the solder 31. The circuit component 500 of the present modification has the same configuration as the circuit component 400 shown in fig. 9 except for the through hole 56.

In this modification, by providing the through hole 56 filled with the electroless plating film 71 inside, the heat generated in the mounting member 30 is easily released to the rear surface 50b through the electroless plating film 71. This can further improve the heat dissipation performance of the circuit component 500. Further, by forming the electroless plating film 71 inside the through hole 56, it is possible to suppress a decrease in mechanical strength of the mounting portion 52 in which the through hole 56 is formed.

The through hole 56 may also be formed by laser processing, for example. The electroless plated film 71 inside the through hole 56 may be formed simultaneously when the circuit pattern 70 is formed by the electroless plated film, for example.

In the present modification, the through hole 56 is provided, but the present embodiment is not limited thereto, and the hole provided in the mounting surface 50a does not necessarily have to penetrate to the bottom surface 55 b. That is, a non-through hole may be provided instead of the through hole 56, and for example, a recess may be formed from the mounting surface 50a to the bottom surface 55b of the mounting portion 52, and an electroless plating film may be formed on the surface of the recess. The through hole is preferable because the electroless plating solution can be more easily flowed by the through hole from the viewpoint of forming the electroless plating film. On the other hand, from the viewpoint of mechanical strength of the mounting portion 52 and prevention of corrosion of the electroless plating film formed therein, a recess portion in which the hole provided in the mounting surface 50a does not penetrate to the bottom surface 55b is more preferable. The concave portion can also achieve the effect of improving the heat radiation property of the circuit part 500. The depth of the recess from the mounting surface 50a to the bottom surface 55b of the mounting portion 52 may be arbitrarily determined as long as it is deeper than the thickness of the electroless plating film for forming the circuit pattern. The recess is not limited to a hole extending in a direction perpendicular to the mounting surface 50a, and may be a groove extending in the mounting surface 50 a.

Examples

The present invention will be further described below with reference to examples and comparative examples. However, the present invention is not limited to the examples and comparative examples described below.

[ production of sample 1-1 ]

A molded foam was produced, and a circuit pattern was formed on the molded foam by plating to obtain a molded circuit member (sample 1-1). In the production of the foamed molded article, polyphenylene sulfide (PPS) (manufactured by Polyplastics, Durafide1130T6) was used as a thermoplastic resin, and nitrogen gas was used as a physical foaming agent. The pressure of the physical blowing agent introduced into the starvation zone of the plasticizing cylinder was set to 1 MPa.

(1) Apparatus for producing foamed molded body

A foamed molded article was produced using the production apparatus 1000 shown in fig. 2 used in the above embodiment. The manufacturing apparatus 1000 will be described in detail. As described above, the manufacturing apparatus 1000 is an injection molding apparatus, and includes the plasticizing cylinder 210, the tank 100 as a physical blowing agent supply mechanism that supplies a physical blowing agent to the plasticizing cylinder 210, a mold clamping unit (not shown) in which a mold is provided, and a control device (not shown) for controlling the operation of the plasticizing cylinder 210 and the mold clamping unit.

A shutoff valve 28 that is opened and closed by driving of the air cylinder is provided at the nozzle tip 29 of the plasticizing cylinder 210, and the inside of the plasticizing cylinder 210 can be maintained at a high pressure. The nozzle tip 29 is closely fitted to a mold (not shown), and a molten resin is injected from the nozzle tip 29 and filled into a cavity formed in the mold. A resin supply port 201 for supplying the thermoplastic resin to the plasticizing cylinder 210 and an introduction port 202 for introducing the physical blowing agent into the plasticizing cylinder 210 are formed in this order from the upstream side on the upper side surface of the plasticizing cylinder 210. The resin supply port 201 and the introduction port 202 are provided with a resin supply hopper 211, a feed screw 212, and an introduction speed adjusting container 300, respectively. The tank 100 is connected to an introduction rate adjusting tank 300 through a pressure reducing valve 151, a pressure gauge 152, and an opening valve 153 by a pipe 154. In addition, a sensor 27 is provided in the starvation area 23 of the plasticizing cylinder 210 to monitor the pressure in the starvation area 23.

In order to promote the plasticizing and melting of the thermoplastic resin, and to perform the measurement and injection of the molten resin, the screw 20 is provided in the plasticizing cylinder 210 so as to be rotatable and movable forward and backward. As described above, the screw 20 is provided with the seal portion 26 and the large diameter portion 20A of the screw 20 as a mechanism for increasing the flow resistance of the molten resin.

In the plasticizing cylinder 210, the thermoplastic resin is supplied from the resin supply port 201 into the plasticizing cylinder 210, and the thermoplastic resin is plasticized by a belt heater (not shown in the figure), formed into a molten resin, and conveyed downstream by the forward rotation of the screw 20. Due to the presence of the seal portion 26 and the large diameter portion 20A provided in the screw 20, the molten resin is compressed and the pressure is increased on the upstream side of the seal portion 26, and the molten resin is in an unfilled state (starved state) in the starvation zone 23 downstream of the seal portion 26. Further, the molten resin conveyed downstream is recompressed near the front end of the plasticizing cylinder 210 and measured before injection.

Thus, a plasticizing zone 21 where the thermoplastic resin is plasticized and melted, a compression zone 22 where the pressure of the molten resin is increased by being compressed, a flow rate adjusting zone 25 where the flow rate of the molten resin is adjusted, a starvation zone 23 where the molten resin is not filled, and a recompression zone 24 where the molten resin decompressed in the starvation zone is recompressed are formed in this order from the upstream side in the plasticizing cylinder 210.

In the manufacturing apparatus 1000, the plasticizing cylinder 210 had an inner diameter of 22mm, and the introduction port 202 had an inner diameter of 6 mm. Therefore, the inner diameter of the introduction port 202 is about 27% of the inner diameter of the plasticizing cylinder 210. Further, the volume of introduction rate adjustment vessel 300 was about 80mL, and the volume of starvation zone 23 was 110 mL. Thus, the volume of introduction rate adjustment vessel 300 is about 0.7 times the volume of starvation zone 23. Further, a mold having a cavity size of 5cm × 5cm × 2mm was used.

(2) Production of foamed molded article

As the tank 100, a nitrogen gas tank having a volume of 47L filled with nitrogen gas at 14.5MPa was used. First, the pressure reducing valve 151 was set to 1MPa, the tank 100 was opened, and 1MPa of nitrogen gas was supplied from the inlet 202 of the plasticizing cylinder 210 to the starvation zone 23 through the pressure reducing valve 151, the pressure gauge 152, and the introduction speed adjusting container 300. In the production of the molded article, the can 100 is always open.

In the plasticizing cylinder 210, the plasticizing zone 21 is adjusted to 320 to 300 ℃, the compression zone 22 is adjusted to 320 ℃, the flow rate adjusting zone 25 and the starvation zone 23 are adjusted to 300 ℃, and the recompression zone 24 is adjusted to 320 ℃ by a belt heater (not shown). While the feed screw 212 was rotated at a rotation speed of 30rpm, resin pellets of thermoplastic resin (PPS) were supplied from the resin supply hopper 211 to the plasticizing cylinder 210, and the screw 20 was rotated in the forward direction. In this way, the thermoplastic resin is heated and kneaded in the plasticizing zone 21 to be a molten resin.

The number of revolutions of the feed screw 212 is determined by setting molding conditions (condition setting) in advance in accordance with the molding of a solid molded body (non-foamed molded body). Here, starvation supply of resin pellets means a state in which the supply of resin pellets in the plasticizing zone 21 in which the resin pellets or the molten resin thereof do not fill the inside of the plasticizing cylinder is maintained and the flights of the screw 20 are exposed from the supplied resin pellets or the molten resin thereof. The confirmation of the starvation supply of the resin pellets includes, for example, a method of confirming the presence or absence of the resin pellets or the molten resin on the screw 20 by an infrared sensor or a visual camera. The feed screw 212 used was provided with a transparent window, and the state of the plasticizing zone 21 below the resin supply port 201 was observed through the transparent window.

The molten resin was caused to flow from the plasticizing zone 21 to the compression zone 22 and further into the flow rate adjusting zone 25 and the starvation zone 23 by setting the back pressure of the screw 20 to 3MPa (pressure of physical blowing agent: 1MP +2MPa to 3MPa) and rotating at a rotation speed of 100 rpm.

The molten resin flows from the clearance between the screw large diameter portion 20A and the seal portion 26 and the inner wall of the plasticizing cylinder 210 to the flow speed adjusting region 25 and the starvation region 23, and therefore the supply amount of the molten resin to the starvation region 23 is limited. Thereby, the molten resin is compressed and increased in pressure in the compression zone 22, and the molten resin is in an unfilled state (starved state) in the starvation zone 23 on the downstream side. In the starvation zone 23, since the molten resin is not filled (starved state), a physical blowing agent (nitrogen gas) introduced from the inlet 202 exists in a space where the molten resin does not exist, and the molten resin is pressurized by the physical blowing agent.

Further, the molten resin is sent to the recompression zone 24 to be recompressed, and as the screw 20 is retreated, the molten resin is measured at the tip end portion of the plasticizing cylinder 210 by 1 shot. Thereafter, the shut-off valve 28 was opened, and a molten resin was injected and filled into the cavity so that the filling rate became 90% of the cavity volume, thereby molding a flat foam molded article (short shot method). The mold temperature was set at 150 ℃. After molding, the foamed molded article is cooled and taken out of the mold. The cooling time was set to 10 seconds.

The injection molding of the molded article described above was continuously performed 20 times to obtain 20 foamed molded articles. In the production of 20 foamed molded articles, the pressure sensor 27 is used to measure the pressure in the starved area 23 in the plasticizing cylinder 210. As a result, the pressure in the starved zone 23 was always stabilized at 1 MPa. The value of the pressure gauge 152 indicating the pressure of the nitrogen gas supplied to the starved area 23 was 1MPa in the production of the foamed molded article. From the above, it was confirmed that the molten resin was always pressurized due to the nitrogen gas of 1MPa in the starvation zone 23 throughout 1 cycle of the injection molding including the plasticization measurement process, the injection process, the cooling process of the molded body, the take-out process, and the like, and the molten resin was always pressurized due to the nitrogen gas in the starvation zone 23 in the continuous molding process of 20 molded bodies.

(3) Formation of circuit patterns

A circuit pattern formed of a plated film is formed on the foam molded body by the method described below.

(a) Synthesis of catalyst activity inhibitors

A hyperbranched polymer represented by the formula (2) was synthesized by introducing an amide group into a commercially available hyperbranched polymer represented by the formula (1) (Hypertech HPS-200, manufactured by Nissan chemical industries, Ltd.).

[ solution 1]

[ solution 2]

First, a hyperbranched polymer represented by the formula (1) (1.3g, dithiocarbamate group: 4.9mmol), N-isopropylacrylamide (NIPAM) (1.10g, 9.8mmol), α' -Azobisisobutyronitrile (AIBN) (81mg, 0.49mmol) and dehydrated Tetrahydrofuran (THF) (10mL) were put in a Schlenk tube and subjected to 3 times of freeze degassing. Thereafter, the reaction was stirred at 70 ℃ evening-out (18 hours) using an oil bath, and after completion of the reaction, the reaction was cooled with ice water and diluted with THF as appropriate. Then, the resulting solid was reprecipitated in hexane, and the resulting solid product was dried at 60 ℃ under vacuum at once. The resultant was subjected to NMR (nuclear magnetic resonance) measurement and IR (infrared absorption spectrum) measurement. As a result, it was confirmed that introduction of an amide group into a commercially available hyperbranched polymer represented by the formula (1) produced a polymer represented by the formula (2). Next, the molecular weight of the product was measured by GPC (gel permeation chromatography). The molecular weight is a number average molecular weight (Mn) of 9,946 and a weight average molecular weight (Mw) of 24,792, and is a value in which the number average molecular weight (Mn) and the weight average molecular weight (Mw) are greatly different from each other. The yield of the hyperbranched polymer represented by the formula (2) was 92%.

(b) Formation of catalyst activity inhibiting layer

The polymer represented by the formula (2) was dissolved in methyl ethyl ketone to prepare a polymer solution having a polymer concentration of 0.5% by weight. The molded foam was immersed in the prepared polymer solution at room temperature for 5 seconds, and then dried in a dryer at 85 ℃ for 5 minutes. Thereby, a catalyst activity suppressing layer is formed on the surface of the foamed molded article. The thickness of the catalyst activity suppressing layer was about 70 nm.

(c) Laser drawing

The surface of the foam molding formed with the catalyst activity suppression layer was subjected to laser drawing of a portion corresponding to the circuit pattern at a processing speed of 2000mm/s using a 3D laser marker (fiber laser, manufactured by kirs) with an output of 50W. The line width of the drawn pattern was set to 0.3mm, and the minimum distance between adjacent drawn lines was set to 0.5 mm. The catalyst activity suppressing layer of the laser-drawn portion may be removed by laser drawing.

(d) Impartation of electroless plating catalyst and formation of plating film

The foamed molded article subjected to laser drawing was immersed in a palladium chloride solution (manufactured by Orye pharmaceutical industry, activator) at 30 ℃ for 5 minutes to apply an electroless plating catalyst. The foamed molded article having the electroless plating catalyst applied thereto was washed with water, and then immersed in an electroless nickel-phosphorus plating solution (manufactured by Oye pharmaceutical industries, Top Nicolon LPH-L, pH6.5) at 60 ℃ for 10 minutes. A nickel-phosphorus film (electroless nickel-phosphorus film) was selectively grown on the laser drawing portion of the foam molded body by about 1 μm.

On the nickel-phosphorus film of the laser drawing portion, a 10 μm copper electroplating plated film, a1 μm nickel electroplating plated film, and a 0.1 μm gold electroplating plated film were further laminated in this order by a general method to form a circuit pattern.

[ production of samples 1-2 to 1-10 ]

Samples 1-2 to 1-10 (molded circuit members) were produced in the same manner as in sample 1-1 except that the pressure of the physical foaming agent introduced into the starved area of the plasticizing cylinder was set to 2MPa, 4MPa, 6MPa, 8MPa, 10MPa, 12MPa, 14MPa, 18MPa, and 0.4MPa, respectively, in the production of the foamed molded article.

In the production of each sample foamed molded article, the pressure sensor 27 is used to measure the pressure in the starved area 23 in the plasticizing cylinder 210. As a result, the pressure in starved area 23 is at the same fixed pressure as the physical blowing agent being introduced. In addition, in the production of the foamed molded article, the value of the pressure gauge 152 indicating the pressure of the nitrogen gas supplied to the starved area 23 is also a constant pressure which is always set for each sample. From the above results, it was confirmed that in the starvation region 23, the molten resin was always pressurized by the nitrogen gas of the fixed pressure set for each sample throughout 1 cycle of the injection molding including the plasticization measurement process, the injection process, the cooling process of the molded body, the take-out process, and the like, and in the starvation region 23, the molten resin was always pressurized by the nitrogen gas in the continuous molding process of 20 molded bodies.

[ evaluation of samples 1-1 to 1-10 ]

The evaluation of the samples 1-1 to 1-10 (molded circuit parts) was carried out by the following method. The evaluation results of the respective samples are shown in tables 1 and 2 together with the pressure of the physical blowing agent used in the production of the foamed molded articles of the respective samples.

(1) Foamability of foam molded article

The foamed molded article was subjected to shape observation and cross-sectional observation, and the foamability of the foamed molded article was evaluated according to the following evaluation criteria. The foamed molded article judged as a in the following judgment standards had a weight loss of about 10% as compared with the solid molded article.

< evaluation Standard of foamability >

And A, fully foaming.

The molded foam completely fills the cavity of the mold, and the cells formed inside the molded foam are miniaturized (cell diameter is about 30 to 50 μm).

And B, foaming.

The foamed molded body does not completely fill the cavity of the mold, but the end portion of the cavity has no unfilled portion. That is, the flow tip of the molten resin reaches the end of the cavity. Among the cells formed in the foamed molded article, enlarged cells (cell diameter of about 100 to 200 μm) are rarely observed.

And C, only a part of the molded body is foamed.

The end of the cavity of the mold has an unfilled portion. That is, the flow end of the molten resin does not reach the end of the cavity. In the vicinity of the end of the foamed molded article (in the vicinity of the end of the molten resin flow), the foamed cells formed are enlarged (cell diameter is about 100 to 200 μm).

(2) Rate of change of thickness of molded circuit part by heat test

5 molded circuit parts were randomly selected from the 20 molded circuit parts of the samples 1-1 to 1-10 thus prepared. First, the length (thickness Db) of a portion corresponding to the thickness of the flat plate (a portion corresponding to the cavity width 2mm of the mold) at 4 was measured for 1 molded circuit component. Thereafter, a heating test described below was performed. First, the molded circuit component was left to stand in an electric furnace heated to a set temperature of 250 ℃ in a reflow furnace assumed to be a lead-free solder. The thermocouple was brought into contact with the surface of the molded circuit part, and the surface temperature was measured to confirm that the maximum temperature reached was 240 ℃ to 260 ℃. After the surface temperature reached the maximum temperature for 5 minutes, the molded circuit part was taken out of the electric furnace. The time for the formed circuit part to stand in the electric furnace is about 8-9 minutes. After the molded circuit member was cooled to room temperature, the thickness (thickness Da) of the portion having the measured thickness before heating was measured again, and the rate of change in the thickness of the molded circuit member due to the heating test was determined by the following equation.

(Da－Db)/Db×100(％)

Db: thickness of molded circuit parts before heating

Da: thickness of molded circuit parts after heating

The rate of change in thickness was determined at 4 points for 1 molded circuit part, and the rate of change in thickness was similarly determined for each sample (20 points in total for 4 × 5) for 5 foam molded circuit parts. Then, the average value of the change rate of the thickness at 20 points was defined as the change rate of the thickness of the molded circuit component due to the heating test of each sample.

(3) Swelling of the surface after Heat test

The surface of the molded circuit member after the above-mentioned heat test was observed, and the presence or absence of surface swelling was evaluated according to the following evaluation criteria.

< evaluation criterion of swelling of surface after Heat test >

A: the surface of the molded circuit component is not bulged.

B: a portion of the surface of the molded circuit part had a small bulge (diameter less than 1 mm).

C: the surface of the molded circuit member had a large bulge (diameter 1mm to 3 mm).

D: the surface of the molded circuit member had a larger bulge (diameter of 3mm or more).

(4) Swirl mark on surface of foam molding

The surface of the molded circuit member before the heat test was observed, and the presence or absence of surface swirl marks of the foamed molded article was evaluated according to the following evaluation standards.

< evaluation Standard of spiral marks >

And A, no spin mark is generated or spin mark is generated very slightly.

B: swirl marks were generated on a part of the surface of the molded foam.

C: the surface of the foamed molded article was entirely scratched, and the surface of the foamed molded article was blurred in white.

[ Table 1]

Sample number	1-10	1-1	1-2	1-3	1-4
						Physical blowing agent pressure (MPa)	0.4	1	2	4	6
(1) Foamability	C	B	A	A	A
						(2) Rate of change in thickness (%)	-0.4	-0.3	-0.3	-0.4	-0.3
(3) Swelling of surfaces	A	A	A	A	A
						(4) Rotary mark	A	A	A	A	A

[ Table 2]

Sample number	1-5	1-6	1-7	1-8	1-9
						Physical blowing agent pressure (MPa)	8	10	12	14	18
(1) Foamability	A	A	A	A	A
						(2) Rate of change in thickness (%)	-0.2	0.2	0.8	1.3	3
(3) Swelling of surfaces	A	A	A	C	D
						(4) Rotary mark	A	A	B	C	C

In samples 1-1 to 1-7 in which the pressure of the physical foaming agent used in the production of the foamed molded article was 1 to 12MPa, the foamability of the foamed molded article was good, the rate of change in the thickness of the molded circuit member by the heat test was small, and the swelling of the surface was also small, and it was confirmed that the heat resistance was high. Further, the generation of the swirl marks is also suppressed. In addition, in samples 1-2 to 1-6 in which the pressure of the physical blowing agent used in the production of the foamed molded article was 2 to 10MPa, the foamability was better, the heat resistance was higher, and the occurrence of the swirl marks was less.

In samples 1-8 and 1-9 in which the pressure of the physical blowing agent used in the production of the foamed molded article exceeded 12MPa, the rate of change in the thickness of the molded circuit member by the heat test was large and the surface bulge was also large, as compared with samples 1-1 to 1-7. As seen from this, the heat resistance was lower than that of samples 1-1 to 1-7. In addition, in samples 1 to 8 and 1 to 9, the occurrence of spin marks was also significant. In samples 1 to 10 in which the pressure of the physical foaming agent used in the production of the foamed molded article was lower than 0.5MPa, the foamability of the foamed molded article was insufficient as compared with samples 1 to 7.

[ production of samples 2-1 to 2-8 ]

Samples 2-1 to 2-8 (molded circuit components) were produced in the same manner as sample 1-1 except that Liquid Crystal Polymer (LCP) (made by polyplasics, Laperos S135) was used as the thermoplastic resin, and the pressures of the physical foaming agent (nitrogen gas) introduced into the starved area of the plasticizing cylinder were set to 0.5MPa, 1MPa, 2MPa, 4MPa, 6MPa, 8MPa, 10MPa, and 0.4MPa, respectively.

In the production of each sample foamed molded article, the pressure sensor 27 is used to measure the pressure in the starved area 23 in the plasticizing cylinder 210. As a result, the pressure in starved area 23 is at the same fixed pressure as the physical blowing agent being introduced. In addition, in the production of the foamed molded article, the value of the pressure gauge 152 indicating the pressure of the nitrogen gas supplied to the starved area 23 is also always a fixed pressure set for each sample. From the above results, it was confirmed that in the starvation region 23, the molten resin was always pressurized by the nitrogen gas of the fixed pressure set for each sample throughout 1 cycle of the injection molding including the plasticization measurement process, the injection process, the cooling process of the molded body, the take-out process, and the like, and in the starvation region 23, the molten resin was always pressurized by the nitrogen gas in the continuous molding process of 20 molded bodies.

[ evaluation of samples 2-1 to 2-8 ]

The following evaluations (1) to (4) were carried out on the fabricated samples 2-1 to 2-8 (molded circuit parts) by the same methods as the above samples 1-1 to 1-10.

(1) Foamability of foam molded article

(2) Rate of change in thickness of foamed molded article by heating test

(3) Bulge of surface after heat test

(4) Swirl mark on surface of foam molding

The evaluation results of the respective samples are shown in table 3 together with the pressure of the physical blowing agent used in the production of the foamed molded articles of the respective samples.

[ Table 3]

Sample number	2-8	2-1	2-2	2-3	2-4	2-5	2-6	2-7
									Physical blowing agent pressure (MPa)	0.4	0.5	1	2	4	6	8	10
(1) Foamability	C	B	A	A	A	A	A	A
									(2) Rate of change in thickness (%)	-0.3	-0.3	-0.3	-0.2	0.2	0.7	1.5	2
(3) Swelling of surfaces	A	A	A	A	A	A	B	C
									(4) Rotary mark	A	A	B	A	A	A	B	B

In samples 2-1 to 2-7 in which the pressure of the physical foaming agent used in the production of the foamed molded article was 0.5 to 10MPa, the foamability was good, and the rate of change in the thickness of the foamed molded article in the heat test was small, and it was confirmed that the heat resistance was high. Further, the generation of the swirl marks is also suppressed. In addition, in samples 2-2 to 2-5 in which the pressure of the physical blowing agent used in the production of the foamed molded article was 1 to 6MPa, the foamability was better, the heat resistance was higher, and the occurrence of the swirl marks was less.

In sample 2-8 in which the pressure of the physical foaming agent used in the production of the foamed molded article was 0.4MPa, the foamability of the foamed molded article was insufficient as compared with samples 2-1 to 2-7.

[ sample 3-1]

The circuit member 700 is manufactured using the substrate 10 of the plate-like body shown in fig. 5. Further, an LED (light emitting diode) is used as the mounting member 30.

(1) Shaping of substrates

Polyphenylene Sulfide (PPS) (product of DIC, TZ-2010-a1, thermal conductivity 1W/m · K) containing alumina or the like is used as the thermoplastic resin containing the insulating heat conductive filler. As a molding apparatus, a plate-shaped (50 mm. times.80 mm. times.2 mm) foamed molded article was molded using a molding apparatus disclosed in FIG. 2 of WO2017/007032 as a physical foaming agent and pressurized nitrogen gas. The filling amount of the molten resin in the mold was adjusted so that the density reduction rate of the foam was 5%. The molding conditions were set such that the introduction pressure of the physical blowing agent was 2MPa, the resin temperature was 350 ℃, the mold temperature was 150 ℃, the injection speed was 50mm/s, the clamping pressure was 3tf, and the holding pressure was 0 (zero).

The appearance of the molded foam molded body was observed with an optical microscope. The range of the thickness of the molded foam article from the portion located at the gate of the mold during molding to the portion located at the end of the mold was within 5 μm, and the thickness of the molded foam article was uniform. Further, in a portion (flow end portion) located at the mold end of the molded body, no burr having a size that can be confirmed with a microscope was generated. Further, the cross section of the foamed molded article was observed by SEM. In the skin layer ranging from the surface of the molded article to a depth of about 100 μm, no foam cells were observed. In the core layer ranging from the surface of the molded article to a depth of about 100 μm, fine foamed cells having an average cell diameter of about 50 μm were observed.

(2) Formation of circuit patterns

A circuit pattern 70 formed of a plated film is formed on the substrate 10 by the method described below.

(a) Formation of catalyst activity inhibiting layer

A catalyst activity suppressing layer containing a hyperbranched polymer represented by the formula (2) as a catalyst deactivator used for the production of the above sample 1-1 was formed on the surface of the substrate. Furthermore, the hyperbranched polymer represented by the formula (2) is synthesized by the method disclosed in Japanese patent laid-open publication No. 2017-160518.

The synthesized polymer represented by formula (2) was dissolved in methyl ethyl ketone to prepare a polymer solution having a polymer concentration of 0.3 wt%. The substrate was immersed in the polymer solution at room temperature for 5 seconds and thereafter dried in a dryer at 85 ℃ for 5 minutes. Thus, a catalyst activity suppressing layer having a thickness of about 50nm was formed on the surface of the substrate.

(b) Laser drawing

The surface of the substrate 10 on which the catalyst activity suppression layer was formed was repeatedly drawn 3 times at a processing speed of 800mm/s using a 3D laser marker (fiber laser, manufactured by kirs, output 50W), and a portion corresponding to the circuit pattern 70 was laser-drawn. The line width of the drawn pattern was set to 0.3mm, and the minimum distance between adjacent drawn lines was set to 0.5 mm. By the laser drawing, the catalyst activity suppressing layer of the laser drawing portion 15 (see fig. 7(a) and (b)) can be removed. Further, the laser drawing portion 15 is roughened in surface to expose the filler contained in the base material 10. The laser induced roughening depth was about 50 μm.

(c) Catalyst-imparted pretreatment

A Polyethyleneimine (PEI) (30 wt% solution prepared by Wako pure chemical industries, Ltd.) having a weight average molecular weight of 70,000 and calcium hypophosphite (Daoko pharmaceutical products) were mixed with water to prepare a pretreatment solution so that the amount of PEI (solid content concentration) was 1g/L and the amount of calcium hypophosphite was 5 g/L. The substrate 10 was immersed in the prepared pretreatment solution at room temperature for 5 minutes.

(d) Cleaning of substrates

The substrate was immersed in room-temperature water stirred by air bubbling for 5 minutes to be washed.

(e) Impartation of electroless plating catalyst

The substrate 10 was treated with commercially available palladium chloride (PdCl) adjusted to 35 deg.C₂) Aqueous solution (manufactured by Orye pharmaceutical industry, activator, palladium chloride concentration: 150ppm) for 5 minutes. The substrate was taken out from the palladium chloride aqueous solution and washed with water.

(f) Chemical plating

The substrate 10 was immersed in an electroless nickel-phosphorus plating solution (manufactured by Orye pharmaceutical industry, Top Nicolon LPH-L, pH6.5) adjusted to 60 ℃ for 10 minutes. A nickel-phosphorous film (electroless nickel-phosphorous film) was grown about 1 μm on the laser drawing portion 15 on the substrate 10.

On the nickel-phosphorus film, a copper electroplating film of 20 μm, a nickel electroplating film of 1 μm, and a gold electroplating film of 0.1 μm were further laminated in this order by a general method to form a circuit pattern 70.

(3) Mounting of mounting parts

As the mounting member 30, a surface mount type high brightness LED (NS 2W123BT, 3.0mmx2.0mmx height 0.7mm, manufactured by riya chemical) was used. On the mounting surface 10a of the mounting portion 12 of the substrate 10, 3 mounting components (LEDs) 30 and solder 31 are arranged at positions that can be electrically connected to the circuit pattern 70. The average thickness of the solder is set to about 20 μm. As shown in fig. 5(a), 3 mounting members 30 are connected in series. Next, the substrate 10 is passed through a reflow furnace (solder reflow). The substrate 10 is heated in a reflow oven with the substrate 10 having a maximum attainment temperature of about 240 c and the substrate 10 being heated at the maximum attainment temperature for a time period of about 1 minute. The mounting member 30 was mounted on the substrate 10 by the solder 31, and the circuit member 700 (sample 3-1) was obtained. In addition, the base material 10 is not swelled by solder reflow.

[ samples 3-2]

A circuit member 400 shown in fig. 9 was produced in the same manner as in sample 3-1 except that a substrate 40 (fig. 9) having a concave portion 45 formed on the back surface 40b was used instead of the plate-shaped substrate 10 (fig. 5).

(1) Shaping of substrates

The same material and apparatus as in sample 3-1 were used to mold the foamed molded article under the same molding conditions. However, the concave portion 45 is formed at the same time as the molding of the base material 40 by using a mold having 3 convex portions corresponding to the concave portion 45 in the cavity. The foam molded body has a plate shape (50mm × 80mm × 2mm), and has a recess 45 defined by a side wall 45a and a bottom surface 45b on a back surface 40b corresponding to a mounting surface 40a on which 3 mounting members (LEDs) 30 are mounted. The area of the bottom surface 45b is set to 0.16cm with 4mm × 4mm²The distance d1 from the mounting surface 40a to the bottom surface 45b is set to 0.6 mm. Area of bottom surface 45b (0.16 cm)²) The area of the bottom surface of the mounting member 30 is set to be larger than (3mmx2mm is 0.06 cm)²) Is large.

The appearance of the obtained foamed molded article was observed with an optical microscope. The thickness (d1) of the mounting portion 52 is thinner than the portions other than the mounting portion 52, and there is no problem in filling the resin. Further, as in sample 3-1, the width of the change in the thickness of the foam molded article was within 5 μm, and the thickness (d2) of the portion other than the mounting portion 52 was uniform. Further, in a portion (flow end portion) located at the mold end of the molded body, no burr having a size that can be confirmed with a microscope was generated. Further, the cross section of the foamed molded article was observed by SEM. In the mounting portion 52 having a small thickness (d1), the number of foam cells in the core layer is small compared to the portion other than the mounting portion 52.

(2) Formation of circuit pattern and mounting of mounting component

A circuit pattern 70 was formed on the mounting surface 40a by the same method as in sample 3-1, and the mounting member 30 was mounted to obtain a circuit member 400 (sample 3-2).

[ samples 3 to 3]

A circuit member 500 shown in fig. 10 was produced in the same manner as in sample 3-1 except that the substrate 51 (fig. 10) having the through-holes 56 formed therein and having the recesses 55 filled with the electroless plating film 71 was used instead of the plate-shaped substrate 10 (fig. 5).

(1) Shaping of substrates

The same material and apparatus as in sample 3-1 were used to mold the foamed molded article under the same molding conditions. However, the base material 51 having the recessed portion 55 formed on the back surface 50b was molded using the mold used in sample 3-2. The substrate 51 before formation of the through-hole 56 was the same as the substrate 40 of sample 3-2.

(2) Formation of circuit patterns and vias

After the catalyst activity suppressing layer was formed in the same manner as in sample 3-1, laser drawing was performed. At the time of laser drawing, a through hole 56 is formed by laser light from the mounting surface 50a of the mounting portion 52 to the bottom surface 55b of the recess 55 together with the laser drawing portion 15 (see fig. 7(a) and (b)) corresponding to the wiring pattern. The diameter of the through-hole 56 was set to 0.2mm, and 6 through-holes 56 were formed for each LED 30.

Then, pretreatment for applying a catalyst, washing of the substrate, application of an electroless plating catalyst, and electroless plating were performed in this order by the same method as in sample 3-1. Thereby, the electroless plated film on the laser drawing portion 15 and the electroless plated film 71 inside the through hole 56 are simultaneously formed. Next, in the same manner as in sample 3-1, an electrolytic copper plating film, an electrolytic nickel plating film, and an electrolytic gold plating film were sequentially laminated on the electroless plating film of the laser drawing portion 15, thereby forming a circuit pattern 70.

(3) Mounting of mounting parts

The mounting member 30 was mounted on the mounting surface 50a in the same manner as in sample 3-1, to obtain a circuit member 500 (sample 3-3).

[ samples 3 to 4]

A circuit member 700 (sample 3-4) shown in fig. 5 was produced in the same manner as in sample 3-1, except that the density reduction rate of the foamed molded article as the base material was set to 0.5%. In the molding of the base material, the introduction pressure of the physical foaming agent was set to 1MPa, and the filling amount of the molten resin in the mold was adjusted to 0.5% in the density reduction rate. Further, the clamping pressure and the holding pressure were adjusted so that no burr was generated in the molded article. The other molding conditions were the same as in sample 3-1.

[ samples 3 to 5]

A circuit member 700 (sample 3-5) shown in fig. 5 was produced in the same manner as in sample 3-1, except that the density reduction rate of the foamed molded article as the base material was 1%. In molding the base material, the introduction pressure of the physical foaming agent was set to 1MPa, and the filling amount of the molten resin in the mold was adjusted to 1% in the density reduction rate. Further, the clamping pressure and the holding pressure were adjusted so that no burr was generated in the molded article. The other molding conditions were the same as in sample 3-1.

[ samples 3 to 6]

A circuit member 700 (sample 3-6) shown in fig. 5 was produced in the same manner as in sample 3-1, except that the density reduction rate of the foamed molded article as the base material was 7%. In the molding of the base material, the introduction pressure of the physical foaming agent was set to 2MPa, and the filling amount of the molten resin in the mold was adjusted to 7% for the density reduction rate. Further, the clamping pressure is adjusted so that burrs are not generated in the molded article. The other molding conditions were the same as in sample 3-1.

[ samples 3 to 7]

A circuit member 700 (sample 3-7) shown in fig. 5 was produced in the same manner as in sample 3-1, except that the density reduction rate of the foamed molded article as the base material was 10%. In the molding of the base material, the introduction pressure of the physical foaming agent was set to 2MPa, and the filling amount of the molten resin in the mold was adjusted to 10% for the density reduction rate. Further, the clamping pressure is adjusted so that burrs are not generated in the molded article. The other molding conditions were the same as in sample 3-1.

[ samples 3 to 8]

A circuit member having the same configuration as that of sample 3-1 was produced, except that the base material was a non-foamed molded article (solid molded article).

(1) Shaping of substrates

A non-foamed molded article was molded using the same material and apparatus as in sample 3-1. In order to mold the non-foamed molded article, the introduction of a physical foaming agent into the plasticizing cylinder is not performed. The resin temperature and the mold temperature were set to be the same as in sample 3-1. However, in samples 3 to 8, the fluidity of the molten resin is low, and therefore sink marks occur in the molded article if no holding pressure is applied during injection molding. Thus applying a dwell pressure of 40MPa for 5 seconds. Further, the clamping pressure was 40tf so that the mold did not open during molding.

The appearance of the obtained foamed molded article was observed with an optical microscope. The range of variation in thickness of the molded foam from the portion located at the gate of the mold during molding to the portion located at the end of the mold was 10 μm, which is different from the range of variation of 5 μm in sample 3-1. Further, burrs having a length of about 50 μm were generated in the molded article at the portion corresponding to the mold parting surface, and the level was such that 2 times of deburring was necessary.

(2) Formation of circuit pattern and mounting of mounting component

In the same manner as in sample 3-1, a circuit pattern was formed on the mounting surface of the molded article, and a mounting member was mounted to obtain a circuit member (sample 3-8).

[ samples 3 to 9]

A circuit member 700 (sample 3-9) shown in fig. 5 was produced in the same manner as in sample 3-1, except that the density reduction rate of the foamed molded article as the base material was set to 15%. In the molding of the base material, the introduction pressure of the physical foaming agent was set to 4MPa, and the filling amount of the molten resin in the mold was adjusted to 15% in the density reduction rate. The other molding conditions were the same as in sample 3-1.

[ evaluation of Circuit Components ]

The following evaluation was performed on the manufactured circuit members (sample 3-1 to sample 3-9). The results are shown in Table 4.

(1) Heat radiation property of circuit component

A power supply was connected to each of the manufactured circuit components (sample 3-1 to sample 3-9), and 300mA of direct current was applied to light the LED 30. After the temperature of the LED30 had stabilized sufficiently for 30 minutes, the temperature of the LED30 was measured. The temperature of the LED30 was measured by fixing a thermocouple between electrodes on the back surface of the LED 30.

(2) Mass-producibility of base material (molded article)

The mass productivity of the base material (molded article) was evaluated according to the following evaluation criteria.

< evaluation Standard of Mass producibility >

O: can be molded under molding conditions of a mold clamping pressure of less than 5tf and a holding pressure of less than 10MPa, and no burr is generated in the molded article.

And (delta): the molding can be carried out under the molding conditions of mold clamping pressure of 5-10 tf and pressure maintaining of 10-20 MPa, and burrs are not generated on a molded body.

X: the molding can be carried out under molding conditions of a mold clamping pressure of 35tf or more and a holding pressure of 40MPa or more, but burrs are generated in the molded article.

[ Table 4]

As shown in Table 4, in the circuit members of samples 3-1 to 3-7, the temperature of the LED was suppressed to 90 ℃ or lower, the heat dissipation was high, and the mass productivity of the molded body was also good. Samples 3-1 to 3-3 having different shapes of the base material and the same conditions were compared. The temperature of the LED was lower in the circuit member 400 (fig. 9) having the concave portion in the base material of sample 3-2, and further, in the circuit member 500 (fig. 10) having the concave portion and the through hole in the base material of sample 3-3, compared to the circuit member 700 (fig. 5) of sample 3-1 using the base material of the plate-like body. That is, the exothermic property was improved in the order of samples 3-3, 3-2, and 3-1.

In addition, samples 3-1, 3-4 to 3-7 and 3-9, which have different density reduction ratios of the base material and the same conditions, were compared. In samples 3-1, 3-5 and 3-6 in which the density reduction rate of the base material was 1 to 7%, the heat release property was high and the mass productivity of the molded article was particularly good. The temperature of the LEDs of samples 3-1, 3-5 and 3-6 was substantially the same as that of the case where the non-foamed molded article was used as the substrate (sample 3-8), and it was confirmed that the LEDs had the same heat release property as the non-foamed molded article. The mass productivity of sample 3-4 having a density reduction rate of 0.5% was slightly lower than that of samples 3-1, 3-5 and 3-6, and the temperature of the LED was slightly increased in sample 3-7 having a density reduction rate of 10%. Further, in sample 3-9 in which the density reduction rate of the base material was 15%, the mass productivity of the molded article was good, but the temperature of the LED was higher and the heat dissipation property was lowered as compared with samples 3-1, 3-5 and 3-6. In samples 3 to 9 in which the density reduction rate of the base material was high, it is presumed that the effect of the insulating heat conductive filler in the base material was reduced because the thermal resistance of the base material was increased by the heat insulating effect of the foamed cells.

On the other hand, in samples 3 to 8 using the non-foamed molded article as the base material, the mass productivity of the molded article was low.

Industrial applicability

The manufacturing method of the present invention can simplify the mechanism of the apparatus related to the physical blowing agent. Further, a foamed molded article having excellent foamability can be produced at low cost and with high efficiency. Further, a molded circuit component having high heat resistance can be manufactured. Further, the circuit component (MID) of the present invention can achieve both mass productivity and heat dissipation. Therefore, the circuit component can be prevented from becoming high temperature due to heat generation of the mounting component such as the LED, and is suitable for mass production, and therefore, the circuit component can be applied to a smartphone and an automobile component.

Description of the symbols

20: screw, 21: plasticizing zone, 22: compression zone, 23: starvation zone, 24: recompression zone, 25: flow velocity adjusting region, 26: sealing portion, 27: pressure sensor, 100: a can, 210: plasticizing cylinder, 300: introduction speed adjusting container, 1000: manufacturing apparatus, 10, 40, 51: substrate, 70: circuit pattern, 30: mounting component (LED), 11: foaming cells, 700, 400, 500: a circuit component.

Claims

1. A circuit member, comprising:

as a base material for a thermoplastic resin-containing foamed molded article, and

a circuit pattern and a mounting surface on the substrate;

the base material is an injection foam molding containing the thermoplastic resin and having a density reduction rate of 0.5% to 10%, and has a back surface facing the circuit pattern and the mounting surface,

the circuit pattern is formed on the surface of the base material including the mounting surface.

2. The circuit component of claim 1,

the thermoplastic resin contains a super engineering plastic,

when the circuit member is heated and the surface temperature of the circuit member is maintained at 240 to 260 ℃ for 5 minutes, the rate of change in the thickness of the circuit member due to heating is-2 to 2%.

3. The circuit component of claim 1,

the circuit component contains an insulating heat conductive filler,

the circuit member has a mounting member mounted on the mounting surface of the base material and electrically connected to the circuit pattern,

the distance from the mounting surface to the back surface of the base material at the portion where the mounting member is mounted is 0.1mm or more.

4. The circuit component of claim 3,

the density reduction rate of the base material is 1-7%.

5. Circuit component according to claim 3 or 4,

the distance from the mounting surface to the back surface of the base material at the portion where the mounting member is mounted is more than 0.5 mm.

6. The circuit component of claim 5,

the base material has a foam cell between the mounting surface and the back surface in a portion where the mounting member is mounted.

7. Circuit component according to claim 3 or 4,

a concave portion defined by a side wall and a bottom surface is formed on the rear surface,

the mounting member is mounted on the mounting surface corresponding to the bottom surface,

the distance from the mounting surface to the bottom surface is 0.1 mm-1.5 mm.

8. The circuit component of claim 7,

the bottom surface has an area of 0.4cm for each of the mounting members arranged on the mounting surface corresponding to the bottom surface²～4cm²。

9. The circuit component of claim 7,

a non-through or through hole is formed from the mounting surface to the bottom surface, and an electroless plating film is formed on the inner wall of the hole.

10. The circuit component of claim 7,

in the portion of the base member to which the mounting member is attached, a recess is formed in the mounting surface, and an electroless plating film is formed on the surface of the recess.

11. The circuit component of claim 3 or 4,

the circuit pattern includes an electroless plating film.

12. Circuit component according to claim 3 or 4,

no heat-releasing member is provided on the rear surface.

13. The circuit component of claim 3 or 4,

the thermoplastic resin contains a super engineering plastic.

14. Circuit component according to one of claims 1 to 4,

the thermoplastic resin contains super engineering plastic, and the super engineering plastic contains polyphenylene sulfide or liquid crystal polymer.

15. A method of manufacturing a circuit member, characterized in that,

manufacturing an electric circuit member using a plasticizing cylinder having a plasticizing region that plasticizes and melts a thermoplastic resin to form a molten resin and a starvation region that causes the molten resin to assume a starvation state, and formed with an introduction port for introducing a physical blowing agent in the starvation region;

the manufacturing method comprises the following steps:

plasticizing and melting the thermoplastic resin in the plasticizing zone to form the molten resin,

introducing a pressurized fluid containing said physical blowing agent at a fixed pressure into said starvation zone and maintaining said starvation zone at said fixed pressure,

causing the molten resin to assume a starvation state in the starvation zone,

contacting the molten resin in a starved state with the pressurized fluid containing the physical blowing agent at a fixed pressure in the starved zone while maintaining the starved zone at the fixed pressure,

molding the molten resin contacted with the pressurized fluid containing the physical foaming agent into an injection foam molded body having a density reduction rate of 0.5 to 10% and a thickness variation rate of-1 to 1%, and

forming a circuit pattern on the surface of the injection foaming molded body;

the thermoplastic resin is super engineering plastic, and the fixed pressure is 0.5 MPa-12 MPa.

16. The method of manufacturing a circuit member according to claim 15,

the super engineering plastic contains polyphenylene sulfide or liquid crystal polymer.

17. The method of manufacturing a circuit member according to claim 15,

the super engineering plastic contains polyphenylene sulfide, and the fixed pressure is 2 MPa-12 MPa.

18. The method for manufacturing a circuit member according to any one of claims 15 to 17,

the circuit pattern comprises an electroless plating film,

the process of forming the circuit pattern on the surface of the foaming molded body comprises the following steps:

forming a catalyst activity suppressing layer containing a polymer having at least one of an amide group and an amino group on the surface of the molded foam,

heating or irradiating light to a part of the surface of the foam molding on which the catalytic activity suppression layer is formed,

imparting electroless plating catalyst to the surface of the foam molding body heated or irradiated with light, and

and contacting the surface of the foam molding to which the electroless plating catalyst is applied with an electroless plating solution to form the electroless plating film on the heated portion or the light irradiated portion of the surface.