CN210694467U

CN210694467U - Multilayer board

Info

Publication number: CN210694467U
Application number: CN201921560608.4U
Authority: CN
Inventors: 苏陟; 张美娟
Original assignee: Guangzhou Fangbang Electronics Co Ltd
Current assignee: Guangzhou Fangbang Electronics Co Ltd
Priority date: 2019-09-18
Filing date: 2019-09-18
Publication date: 2020-06-05
Anticipated expiration: 2029-09-18

Abstract

The embodiment of the utility model provides a multilayer board, including first circuit substrate and second circuit substrate; the first circuit substrate comprises a base film layer, a first conducting layer and a first medium layer, wherein the first conducting layer and the first medium layer are sequentially arranged on one surface of the base film layer, and a first through hole is formed in the first medium layer; the second circuit substrate comprises a first adhesive film layer and a second conducting layer which are arranged in a stacked mode, and the first adhesive film layer is arranged on one surface, far away from the first conducting layer, of the first dielectric layer; and a first protruding structure is arranged on one surface of the metal layer in the second conducting layer, pierces the first adhesive film layer and penetrates through the first through hole to be connected with the metal layer in the first conducting layer. The utility model discloses a multiply wood has reduced the whole thickness of multiply wood widely, has strengthened the resistant bending nature of multiply wood to improve the reliability and the convenience of multiply wood equipment, makeed the multiply wood be applicable to high frequency signal transmission.

Description

Multilayer board

Technical Field

The utility model relates to the field of electronic technology, especially, relate to a multiply wood.

Background

With the rapid development of the electronic industry, electronic products are further miniaturized, light-weighted, multifunctional and densely assembled, and flexible circuit boards are widely used in electronic products because of their advantages of small size, light weight and high flexibility.

In order to meet the development requirements of high frequency and high speed digitization of signal transmission and ensure the normal operation of electronic products, the design and material selection of the adopted multilayer flexible circuit board must be optimized. At present, the conventional flexible circuit board usually adopts a dielectric layer with low dielectric loss, or reduces the dielectric constant, or changes the thickness and material of the dielectric layer to reduce the fluctuation of characteristic impedance, thereby ensuring that the requirements of high frequency and high speed digitization of signal transmission are met under the normal operation of electronic products. However, the multilayer flexible wiring board itself has a large thickness, which results in poor bending performance and low space utilization, and therefore, the application of the flexible wiring board in high-frequency signal transmission is limited.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a multiply wood can reduce the whole thickness of circuit board, and the resistant bending nature of reinforcing circuit board is effectively applied to high frequency signal transmission.

In order to solve the above technical problem, an embodiment of the present invention provides a multi-layer board, including a first circuit substrate and a second circuit substrate;

the first circuit substrate comprises a base film layer, a first conducting layer and a first medium layer, wherein the first conducting layer and the first medium layer are sequentially arranged on one surface of the base film layer, and the first medium layer is provided with at least one first through hole for exposing a metal layer in the first conducting layer;

the second circuit substrate is arranged on one side, close to the first dielectric layer, of the first circuit substrate; the second circuit substrate comprises a first adhesive film layer and a second conducting layer which are arranged in a stacked mode, and the first adhesive film layer is arranged on one surface, far away from the first conducting layer, of the first dielectric layer; and a first protruding structure is arranged on one surface, facing the first adhesive film layer, of the metal layer in the second conducting layer, and the first protruding structure pierces through the first adhesive film layer and penetrates through the first through hole to be connected with the metal layer in the first conducting layer.

As an improvement of the above scheme, the number of the second circuit substrates arranged on one side of the first circuit substrate close to the first dielectric layer is multiple; a second dielectric layer is arranged between any two adjacent second circuit substrates, and each second dielectric layer is provided with at least one second through hole; in any two adjacent second circuit substrates, the first protruding structure of the second circuit substrate far away from the first circuit substrate pierces through the first adhesive film layer and penetrates through the second through hole, so as to be connected with the metal layer in the second conducting layer of the second circuit substrate close to the first circuit substrate.

As an improvement of the above solution, the number of the first circuit boards is plural, and the plural first circuit boards are sequentially stacked; and any two adjacent first circuit substrates are provided with first connecting holes, and conductive media for connecting the metal layers of the first conductive layers in the two adjacent first circuit substrates are arranged in the first connecting holes.

As an improvement of the above scheme, the multilayer board further includes a third circuit substrate, the third circuit substrate includes a third conductive layer and a third dielectric layer, which are stacked, the third dielectric layer is disposed on a surface of the second conductive layer away from the first glue film layer, the third dielectric layer is provided with a second connection hole, and a conductive medium for connecting a metal layer in the third conductive layer and a metal layer in the second conductive layer is disposed in the second connection hole.

As an improvement of the above scheme, the first circuit substrate further includes a fourth conductive layer and a fourth dielectric layer, and the fourth conductive layer and the fourth dielectric layer are sequentially disposed on the other surface of the base film layer.

As an improvement of the above scheme, at least one third through hole for exposing the metal layer in the fourth conductive layer is formed in the fourth dielectric layer;

the second circuit substrates are also arranged on one side, close to the fourth dielectric layer, of the first circuit substrate, and the second circuit substrates are symmetrically arranged on two sides of the first circuit substrate or are asymmetrically arranged on two sides of the first circuit substrate; and the first bulge structure of the second circuit substrate close to the fourth dielectric layer pierces through the first adhesive film layer of the second circuit substrate and penetrates through the third through hole to be connected with the metal layer in the fourth conducting layer.

As an improvement of the above scheme, the number of the second circuit substrates arranged on one side of the first circuit substrate close to the fourth dielectric layer is multiple; a second dielectric layer is arranged between any two adjacent second circuit substrates, and each second dielectric layer is provided with at least one second through hole; in any two adjacent second circuit substrates, the first protruding structure of the second circuit substrate far away from the first circuit substrate pierces through the first adhesive film layer and penetrates through the second through hole, so as to be connected with the metal layer in the second conducting layer of the second circuit substrate close to the first circuit substrate.

As an improvement of the above scheme, a plurality of third connection holes are formed in the base film layer at intervals, and a conductive medium for connecting the metal layer in the first conductive layer and the metal layer in the fourth conductive layer is disposed in the third connection holes.

As an improvement of the above scheme, the metal layer in the second conductive layer includes a first surface, the first surface is a non-flat surface, and the first surface constitutes the first protruding structure; or the like, or, alternatively,

the metal layer in the second conducting layer comprises a first surface, conductor particles are arranged on the first surface, and the first surface and the conductor particles form the first protruding structure.

As a modification of the above, the height of the first bump structure is 0.2 μm to 30 μm.

As an improvement of the above scheme, the first adhesive film layer includes an adhesive layer containing no conductive particles.

As a modification of the above, the metal layer in the first conductive layer, the metal layer in the second conductive layer, and the metal layer in the fourth conductive layer are made of any one or more materials selected from aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold, respectively.

Compared with the prior art, the multilayer board provided by the embodiment of the present invention is configured with a first through hole formed in the first dielectric layer of the first circuit board to expose the metal layer in the first conductive circuit layer, and a first glue film layer in the second circuit board is disposed on a surface of the first dielectric layer away from the first conductive layer, and a first protrusion structure is disposed on a surface of the metal layer of the second conductive layer in the second circuit board facing the first glue film layer, so that the first protrusion structure pierces the first glue film layer and penetrates through the first through hole to be connected with the metal layer of the first conductive layer, thereby realizing conduction inside the multilayer board; the utility model discloses a multiply wood is with outer impedance control layer of traditional multilayer circuit board and first cover rete replacement for the setting of impedance control layer and first cover rete has been avoided to second circuit substrate to reduce the whole thickness of multiply wood widely, strengthened the resistant bending nature of multiply wood, and improved the reliability and the convenience of multiply wood equipment, make the multiply wood is applicable to high frequency signal transmission.

Drawings

Fig. 1 is a schematic structural diagram of a multilayer board according to a first embodiment of the present invention;

FIG. 2 is a schematic structural diagram of another multi-layer board according to a first embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a multilayer board according to a first embodiment of the present invention;

FIG. 4 is a schematic structural diagram of a multilayer board according to a first embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a multilayer board according to a first embodiment of the present invention;

fig. 6 is a schematic structural view of a multilayer board according to a second embodiment of the present invention;

fig. 7 is a schematic structural view of a multilayer board according to a third embodiment of the present invention;

fig. 8 is a schematic structural view of a multilayer board in a fourth embodiment of the present invention;

fig. 9 is a schematic structural view of a multilayer board according to a fifth embodiment of the present invention;

fig. 10 is a schematic structural view of another multilayer board according to a fifth embodiment of the present invention;

fig. 11 is a schematic structural view of a multilayer board in a sixth embodiment of the present invention;

fig. 12 is a schematic structural view of a multilayer board according to a seventh embodiment of the present invention;

fig. 13 is a schematic structural view of a multilayer board according to an eighth embodiment of the present invention;

fig. 14 is a schematic flow chart of a method for manufacturing a multilayer board according to example nine of the present invention.

The circuit board comprises a first circuit substrate 1; 11. a base film layer; 111. a third connection hole; 12. a first conductive layer; 121. a metal layer in the first conductive layer; 122. an insulating layer in the first conductive layer; 13. a first dielectric layer; 131. a first through hole; 14. a first connection hole; 15. a fourth conductive layer; 151. a metal layer in the fourth conductive layer; 152. an insulating layer in the fourth conductive layer; 16. a fourth dielectric layer; 161. a third through hole;

2. a second circuit substrate; 21. a first adhesive film layer; 22. a second conductive layer; 221. a metal layer in the second conductive layer; 222. an insulating layer in the second conductive layer; 223. a first bump structure; 224. a conductive particle; 3. a second dielectric layer; 31. a second through hole; 4. a conductive medium;

5. a third circuit substrate; 51. a third conductive layer; 511. a metal layer in the second conductive layer; 512. an insulating layer in the second conductive layer; 52. a third dielectric layer; 521. a second connection hole; 6. a first insulating protection layer; 7. and a second insulating protection layer.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

Example one

Referring to fig. 1 to 5, a multi-layer board according to an embodiment of the present invention includes a first circuit substrate 1 and a second circuit substrate 2;

the first circuit substrate 1 includes a base film layer 11, a first conductive layer 12 and a first dielectric layer 13, the first conductive layer 12 and the first dielectric layer 13 are sequentially disposed on one surface of the base film layer 11, and the first dielectric layer 13 is provided with at least one first through hole 131 for exposing the metal layer 121 in the first conductive layer;

the second circuit substrate 2 is arranged on one side, close to the first medium layer 13, of the first circuit substrate 1; the second circuit substrate 2 comprises a first adhesive film layer 21 and a second conductive layer 22 which are stacked, wherein the first adhesive film layer 21 is arranged on one surface of the first dielectric layer 13, which is far away from the first conductive layer 12; a first protruding structure 223 is disposed on a surface of the metal layer 221 of the second conductive layer facing the first adhesive film layer 21, and the first protruding structure 223 pierces through the first adhesive film layer 21 and penetrates through the first through hole 131 to be connected to the metal layer 121 of the first conductive layer.

In the embodiment of the present invention, a first through hole 131 is formed in the first dielectric layer 13 of the first circuit substrate 1 to expose the metal layer 121 in the first conductive layer, and the first glue film layer 21 in the second circuit substrate 2 is disposed on a surface of the first dielectric layer 13 away from the first conductive layer 12, and a first protrusion structure 223 is disposed on a surface of the metal layer 221 of the second conductive layer in the second circuit substrate 2 facing the first glue film layer 21, so that the first protrusion structure 223 pierces the first glue film layer 21 and penetrates through the first through hole 131 to connect with the metal layer 121 of the first conductive layer, thereby achieving conduction inside the multilayer board; the utility model discloses a multiply wood is with outer impedance control layer of traditional multilayer circuit board and first cover rete replacement for second circuit substrate 2 has avoided the setting of impedance control layer and first cover rete to reduce the whole thickness of multiply wood widely, strengthened the resistant bending nature of multiply wood, and improved the reliability and the convenience of multiply wood equipment, make the multiply wood is applicable to high frequency signal transmission. Furthermore, the embodiment of the utility model provides a multiply wood need not to adopt the through-hole of metallization to realize the multiply wood in the layer and be connected electrically between the layer, has avoided manufacturing process such as drilling, hole metallization to the manufacturing process of multiply wood has been simplified, and the cost of manufacture of multiply wood is reduced.

In the embodiment of the present invention, the type of the base film layer 11 can be set according to the actual use requirement; specifically, the base film layer 11 may be provided as a single base film layer, such as a single hard resin layer or a single flexible resin layer; the base film layer 11 may also be a composite base film layer, such as one composed of a plurality of different types of hard resin layers, one composed of a plurality of different types of flexible resin layers, or one composed of a hard resin layer and a flexible resin layer; the hard resin layer is specifically an epoxy resin, a fiberglass cloth, or the like, and the flexible resin layer is specifically a Polyimide (PI), a Polyethylene terephthalate (PET), a polytetrafluoroethylene (Teflon), a polythioamine (Polyamide), a polymethyl methacrylate (polymethyl methacrylate), a Polycarbonate (Polycarbonate), or a Polyimide-Polyethylene-terephthalate copolymer (Polyimide-Polyethylene terephthalate), or the like.

In the embodiment of the present invention, the first conductive layer 12 may be configured as a circuit layer; in the manufacturing process of the circuit board, after etching treatment, a plurality of metal layers are formed on the circuit layer, gaps are formed among the metal layers, and the gaps are filled with glue in the subsequent circuit board pressing process, so that an insulating layer is formed; specifically, as shown in fig. 1, when the first conductive layer 12 is a circuit layer, in the process of laminating the pair of high-transmission laminates, a gap between the metal layers 121 in each of the first conductive layers 12 is filled with the adjacent first dielectric layer 13, so as to form an insulating layer 122 in the first conductive layer; therefore, when the first conductive layer 12 is a circuit layer, the first conductive layer 12 is composed of a metal layer 121 in a plurality of first conductive layers and an insulating layer 122 in a plurality of first conductive layers, and the metal layer 121 in the first conductive layer and the insulating layer 122 in the first conductive layer are connected in an interlaced manner, so that the metal layers 121 in the respective first conductive layers are independent of each other, as shown in fig. 1. In addition, the number of the metal layers 121 in the first conductive layer can also be set according to actual conditions; preferably, the number of the metal layers 121 in the first conductive layers is multiple, and the metal layers 121 in the first conductive layers are independent of each other.

Furthermore, the first conductive layer 1 may also be provided as a metal layer, i.e. it has not been etched, as shown in fig. 3. Similarly, the second conductive layer 2 can also be configured as a circuit layer or a metal layer; when the second conductive layer 2 is a circuit layer, in the process of laminating the multilayer boards, gaps between the metal layers 221 in each second conductive layer in the second conductive layer 2 are filled with the adjacent first insulating protection layers 6, so as to form insulating layers 222 in the second conductive layers; therefore, when the second conductive layer 2 is a wiring layer, the second conductive layer 2 is composed of the metal layer 221 in the plurality of second conductive layers and the insulating layer 222 in the plurality of second conductive layers; in addition, the number of the metal layers 221 in the second conductive layer can be set according to practical situations; preferably, the number of the metal layers 221 in the second conductive layers is multiple, and the metal layers 221 in the second conductive layers are independent of each other.

In the embodiment of the present invention, the number and the positions of the first through holes 131 disposed on the first medium layer 13 may also be set according to actual use conditions. It is understood that the first through hole 131 may be disposed only on the first dielectric layer 13 at a position corresponding to the metal layer 221 in the second conductive layer and the metal layer 121 in the first conductive layer, so that the first protruding structure 223 on the metal layer 221 in the second conductive layer can pierce through the first glue film layer 21 and connect with the metal layer 121 in the corresponding first conductive layer through the disposed first through hole 131, as shown in fig. 2.

In addition, the type of the first medium layer 13 may also be set according to the actual use requirement. Specifically, the first dielectric layer 13 may be a single dielectric layer, such as a glue film layer or a resin film layer; the first dielectric layer 13 may also be configured as a composite dielectric layer, such as a composite dielectric layer including PI (Polyimide) and a binder.

In addition, in the embodiment of the present invention, the first circuit substrate 1 may further include at least one RCC (Resin Coated Copper Foil) plate, one RCC plate is disposed on a surface of the first dielectric layer 13 away from the first conductive layer 12, and/or another RCC plate is disposed on a surface of the base film layer 11 away from the first conductive layer 12.

Specifically, the RCC board includes a copper layer and a second glue film layer, which are stacked, and when one RCC board is disposed on a surface of the first dielectric layer 13 away from the first conductive layer 12, the second glue film layer of the RCC board is disposed on a surface of the first dielectric layer 13 away from the first conductive layer 12, and the copper layer is electrically connected to the first conductive layer 12 through a through hole, a blind hole, or a buried hole; the second circuit substrate 2 is disposed on one side of the first circuit substrate close to the RCC board, specifically: the first glue film layer 21 of the second circuit substrate 2 is arranged on one surface of the copper layer far away from the second glue film layer, a first protruding structure 223 is arranged on one surface, facing the first glue film layer 21, of the metal layer 221 in the second conducting layer, and the first protruding structure 223 pierces through the first glue film layer 21 so as to be electrically connected with the copper layer. In addition, when the other RCC board is disposed on the surface of the base film layer 11 away from the first conductive layer 12, the second adhesive film layer of the RCC board is disposed on the surface of the base film layer 11 away from the first conductive layer 12.

As shown in fig. 1, in order to realize that the first bump structure 223 pierces through the first adhesive film layer 21 and connects with the metal layer 121 of the first conductive layer through the first through hole 131, in a preferred embodiment, the metal layer 221 of the second conductive layer includes a first surface, the first surface is a non-flat surface, and the first surface constitutes the first bump structure 223.

In another preferred embodiment, the metal layer 221 in the second conductive layer includes a first surface on which the conductive particles 224 are disposed, and the first surface and the conductive particles 224 form the first protruding structure 223, as shown in fig. 4. The first protruding structures 223 are formed by disposing the conductor particles 224 on the first surface, so that the piercing strength of the first protruding structures 223 is enhanced, and it is further ensured that the first protruding structures 223 can pierce the first adhesive film layer 21 and pass through the first through holes 31 to be connected with the metal layer 121 in the first conductive layer. When the first surface is provided with the conductive particles 224, the first surface may be a non-flat surface or a flat surface.

In an embodiment of the present invention, when the first surface is an uneven surface, the first surface may be provided as a regular uneven surface or as an irregular uneven surface. Specifically, when the first surface is a regular non-flat surface, the non-flat surface is a structure with periodic fluctuation, and the amplitude of the fluctuation and the interval of the fluctuation on the non-flat surface are the same; when the first surface is an irregular non-flat surface, the non-flat surface is a structure with non-periodic fluctuation, and the amplitude of the fluctuation and the interval of the fluctuation on the non-flat surface are different.

In addition, the metal layer 221 in the second conductive layer further includes a second surface disposed opposite to the first surface, the second surface being in contact with the first insulating protective layer 6; the second surface may be any shape, for example, a flat surface, a non-flat surface that mates with the first surface, or other rough surface. The drawings of the present invention only illustrate the second surface as a flat surface, and the second surface of any other shape is within the protection scope of the present invention.

In an embodiment of the present invention, when the first surface is a non-flat surface, the first surface comprises a plurality of protrusions and recesses; when the first protruding structures 223 are formed by the first surface and the conductive particles 224, the conductive particles 224 are preferably distributed on the protruding portions in a concentrated manner, and the first protruding structures 223 can pierce the first adhesive film layer 21 more easily during the pressing process, so as to ensure the conduction inside the multilayer board. In addition, the conductive particles 224 may also be distributed on other positions of the first surface, not only on the convex portion, as shown in fig. 4. Of course, the conductive particles 224 may also be distributed only on the protrusions.

In a specific implementation, the second conductive layer 22 may be formed first, and then the conductor particles 224 may be formed on the first surface of the metal layer 221 in the second conductive layer by another process. Of course, the metal layer 221 and the conductive particles 224 in the second conductive layer may be an integral structure formed by a one-step molding process.

Based on the above structure, when the first surface is a non-flat surface, the first adhesive film layer 21 extrudes the adhesive on the convex portion of the first surface into the concave portion of the first surface during the pressing process, so as to avoid the phenomenon that the metal layer 121 in the first conductive layer and the metal layer 221 in the second conductive layer are connected and failed due to the phenomenon that the adhesive capacity is small and the plate is easily broken; meanwhile, the conductor particles 224 with a certain height are formed on the first surface, so that the first protruding structures 223 can be ensured to smoothly pierce the first adhesive film layer 21 in the pressing process, and the practicability is high.

In the embodiment of the present invention, the height of the conductor particles 224 can be set according to the actual use condition; preferably, the height of the conductor particles 224 in this embodiment is 0.1 μm to 30 μm. In addition, the conductive particles 224 may be spaced apart from the outer surface of the first adhesive film layer 21, and may contact the outer surface of the first adhesive film layer 21 or extend out of the outer surface of the first adhesive film layer 21.

In an embodiment of the present invention, the conductive particles 224 include one or more of metal particles, carbon nanotube particles, and ferrite particles. Further, the metal particles include single metal particles and/or alloy particles; the single metal particles are made of any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, and the alloy particles are made of any two or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold. The conductive particles 224 may be the same as or different from the metal layer 221 in the second conductive layer.

In addition, the shape of the conductive particles 224 is illustrated as an example, and the conductive particles 224 may have other shapes such as clusters, ice-hanging shapes, stalactites, and dendrites due to differences in process means and parameters. In addition, the conductive particles 224 in the present invention are not limited by the shapes shown in the drawings, and any conductive particles having piercing and conductive functions are within the scope of the present invention.

In the embodiment of the present invention, in order to ensure that the first protruding structure 223 can pierce through the first adhesive film layer 21 and pass through the first through hole 131 to connect with the metal layer 121 in the first conductive layer, the height of the first protruding structure 223 in this embodiment is 0.2 μm to 30 μm. Wherein, preferably, the height of the first projection structure 223 is 0.5 μm to 5 μm. It should be noted that the height of the first convex structures 223 is a distance D1 between the highest point and the lowest point of the first convex structures 223, as shown in fig. 5.

Furthermore, in the embodiment of the present invention, the first protrusion structure 223 may also be disposed on a surface of the metal layer 221 in the second conductive layer away from the first adhesive film layer 21, which is not described herein.

In the embodiment of the present invention, in order to reduce the overall thickness of the circuit board, and at the same time ensure that the metal layer 221 in the second conductive layer can be connected to the metal layer 121 in the first conductive layer through the first protruding structure 223, the thickness of the second conductive layer 22 in this embodiment is 0.1 μm to 9 μm; preferably, the thickness of the second conductive layer 22 is 0.2 μm to 5 μm. In addition, the thickness of the first conductive layer 12 in the embodiment is 0.1 μm to 9 μm; preferably, the thickness of the first conductive layer 12 is 0.2 μm to 5 μm.

In the embodiment of the present invention, the material of the metal layer 121 in the first conductive layer and the metal layer 221 in the second conductive layer may be set according to actual use conditions. In order to simplify the design and structure and reduce the cost, the metal layer 121 in the first conductive layer and the metal layer 221 in the second conductive layer in this embodiment are made of any one or more materials of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold, respectively.

In the embodiment of the present invention, it should be noted that, in the drawings of this embodiment, the metal layer 121 in the first conductive layer and the metal layer 221 in the second conductive layer may both be a single-layer structure or a multi-layer structure; specifically, the multilayer structure may be formed by forming one or more of metals other than the host on the surface of the host using one or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold as a host, and then using one or more of electroplating, electroless plating, physical vapor deposition, and chemical vapor deposition. In this embodiment, the metal layer 121 in the first conductive layer and the metal layer 221 in the second conductive layer are preferably a multilayer structure in which copper is used as a main component and one or more metals of nickel, chromium, silver and gold are formed on the surface of copper, because the metal layer 121 in the first conductive layer and the metal layer 221 in the second conductive layer, which are made of only copper, are easily oxidized or worn, and the nickel, chromium, silver and gold formed on the surface of copper can improve the corrosion resistance and wear resistance of the metal layer 121 in the first conductive layer and the metal layer 221 in the second conductive layer, thereby improving the conductive performance of the multilayer board and prolonging the service life of the multilayer board. In addition, the first conductive layer 12 and the second conductive layer 22 of the present embodiment can be arranged in a grid shape, a foaming shape, etc. according to the requirements of actual production and application.

In the embodiment of the present invention, the first adhesive film layer 21 includes an adhesive layer containing no conductive particles. The first glue film layer 21 has an adhesive function by making the first glue film layer 21 include an adhesive layer without conductive particles, so that the second conductive layer 22 and the first medium layer 13 are tightly adhered; in addition, since the first adhesive film layer 21 does not contain conductive particles, the phenomenon of eddy current loss caused by accumulation of a large amount of charges is effectively avoided, so that the insertion loss of the multilayer board in the use process is reduced, and meanwhile, the multilayer board can bear larger current, so that the multilayer board is ensured to be suitable for transmission of high-frequency and high-speed signals, the integrity of high-frequency signal transmission can be ensured, and in addition, the bending resistance of the multilayer board can be improved.

In the embodiment of the present invention, in order to ensure that the first protruding structures 223 can pierce the first adhesive film layer 21 while the first conductive layer 12 and the first dielectric layer 13 are tightly bonded through the first adhesive film layer 21, the thickness of the first adhesive film layer 21 in this embodiment is 1 μm to 25 μm; preferably, the thickness of the first adhesive film layer 21 is 1 μm to 8 μm. In addition, the material used for the first adhesive film layer 21 is selected from the following materials: modified epoxy resins, acrylic resins, modified rubbers, and modified thermoplastic polyimides. The outer surface of the first adhesive film layer 21 may be a flat surface without undulations or a non-flat surface with gentle undulations.

In the embodiment of the present invention, it should be noted that the impedance control layer of the outer layer of the conventional multilayer board generally includes a first glue layer, a PI (Polyimide) substrate, and a copper substrate; wherein the thickness of the first adhesive layer is 20-25 μm; the thickness of the PI base material is 12.5-50 μm; the thickness of the copper base material is 9-18 μm; the first covering film layer of the outer layer of the traditional multilayer board comprises a second adhesive layer and a PI first covering film layer; wherein the thickness of the second adhesive layer is 20-25 μm; the thickness of the PI first covering film layer is 12.5-50 μm; the thickness of the second conductive layer 22 in the second circuit substrate 2 according to the embodiment of the present invention is 0.1 μm to 9 μm, and the thickness of the first adhesive film layer 21 is 1 μm to 25 μm; therefore, the multilayer board of the present embodiment greatly reduces the overall thickness of the multilayer board by replacing the resistance control layer and the first cover film layer of the outer layer of the conventional multilayer board with the second circuit substrate 2, and enhances the bending resistance of the multilayer board, thereby realizing a highly flexible ultra-thin circuit board.

As shown in fig. 1, in order to protect the multilayer board, the multilayer board in this embodiment further includes a first insulating protection layer 6, where the first insulating protection layer 6 is disposed on a surface of the second conductive layer 22 away from the first adhesive film layer 21. By providing the first insulating protection layer 6, a good isolation protection effect is achieved, and the phenomenon that the second conductive layer 22 is interfered when contacting with other electrical conductors is effectively avoided.

Wherein the thickness of the first insulating protection layer 6 is 1 μm to 25 μm; preferably, the first insulating protective layer 6 has a thickness of 3 μm to 20 μm. In addition, the first insulating protective layer 6 may be a PPS film layer, a PEN film layer, a PET film layer, a PI film layer, a PA film layer, a film layer formed after curing epoxy resin ink, a film layer formed after curing polyurethane ink, a film layer formed after curing modified acrylic resin, or a film layer formed after curing polyimide resin. Of course, the type of the first insulating protection layer 6 may be set according to actual use requirements, and only the requirement that the first insulating protection layer 6 can play a role of isolation protection in the multilayer board is met, which is not described herein in further detail.

Example two

As shown in fig. 6, the multilayer board in the present embodiment is different from the first embodiment in that the number of the second circuit substrates 2 provided on the side of the first circuit substrate 1 adjacent to the first dielectric layer 13 is plural; a second dielectric layer 3 is arranged between any two adjacent second circuit substrates 2, and each second dielectric layer 3 is provided with at least one second through hole 31; in any two adjacent second circuit substrates 2, the first protruding structure 223 of the second circuit substrate 2 far away from the first circuit substrate 1 pierces through the first adhesive film layer 21 and passes through the second through hole 31, so as to connect with the metal layer 121 in the second conductive layer of the second circuit substrate 1 close to the first circuit substrate 1.

In the embodiment of the present invention, the number and the positions of the second through holes 31 disposed on the second medium layer 3 may be set according to actual use conditions. It can be understood that, the second through hole 31 may be disposed on the second dielectric layer 3 at a position corresponding to the metal layer 221 in the two adjacent second conductive layers that need to be electrically connected, so that the first protruding structure 223 on the metal layer 221 in the second conductive layer far from the first circuit substrate 1 in the metal layer 221 in the second conductive layer pierces through the first adhesive film layer 21 and passes through the disposed second through hole 31, so as to be connected to the metal layer 221 in the corresponding second conductive layer near the first circuit substrate 1.

In the embodiment of the present invention, the type of the second medium layer 3 may be set according to actual use conditions. Specifically, the second dielectric layer 3 may be a single dielectric layer, such as a glue film layer or a resin film layer; the second dielectric layer 3 may also be configured as a composite dielectric layer, such as a composite dielectric layer including PI (Polyimide) and a binder.

It should be noted that the number of the second circuit substrates 2 of the multilayer board shown in fig. 6 is 3, which is only an example, and the number of the second circuit substrates 2 in this embodiment may be set according to actual use requirements, so that other embodiments that adjust the number of the second circuit substrates 2 are also within the protection scope of the present invention. In addition, other structures and working principles of the multilayer board of the present embodiment are the same as those of the first embodiment, and further description is omitted here.

EXAMPLE III

As shown in fig. 7, the multi-layer board in this embodiment is different from the first and second embodiments in that the number of the first circuit boards 1 is plural, and the plural first circuit boards 1 are sequentially stacked; any two adjacent first circuit substrates 1 are provided with a first connection hole 14, and a conductive medium 4 connected to the metal layer 121 of the first conductive layer in the two adjacent first circuit substrates 1 is provided in the first connection hole 14.

In the embodiment of the present invention, the conductive medium 4 is attached to the hole wall of the first connection hole 14, so as to form a conductive hole, and the conductive hole can be a through hole, a buried hole, or a blind hole, as shown in fig. 7. Of course, the operator may also choose to fill the entire first connection hole 14 with the conductive medium 4, that is, not form a conductive hole, so as to prevent the etching solution from entering the conductive hole, and protect the conductive medium 4 in the first connection hole 14 from being etched, thereby ensuring the internal conduction of the multilayer board.

In the embodiment of the present invention, the number and the position of the first connection holes 14 may be set according to actual use conditions. It is understood that the first connection holes 14 may be disposed at positions corresponding to the metal layers 121 in the two adjacent first conductive layers, which are required to be electrically connected, so that the metal layers 121 in the first conductive layers in the two adjacent first circuit elements 1 are electrically connected through the conductive medium 4 disposed in the first connection holes 14.

In the embodiment of the present invention, during the multi-layer board lamination process, the first dielectric layer 13 may flow to the first connection hole 14 and the first through hole 131 formed on the first dielectric layer 13, so that the first connection hole 14 and the first through hole 131 are filled with the first dielectric layer 13, as shown in fig. 7; of course, fig. 7 is only an example, and the first connection hole 14 and the first through hole 131 may be filled with the first dielectric layer 13 or may be partially filled, which is not limited by the present invention.

In addition, it should be noted that the number of the first circuit substrates 1 of the multilayer board shown in fig. 7 is 3, which is only an example, the number of the first circuit substrates 1 in the present embodiment may be set according to the actual use requirement, and thus other embodiments that adjust the number of the first circuit substrates 1 are also within the protection scope of the present invention. In addition, other structures and working principles of the multilayer board of the present embodiment are the same as those of the first and second embodiments, and are not further described herein.

Example four

As shown in fig. 8, the multilayer board in this embodiment is different from the first and third embodiments in that the multilayer board further includes a third circuit substrate 5, where the third circuit substrate 5 includes a third conductive layer 51 and a third dielectric layer 52 that are stacked, the third dielectric layer 52 is disposed on a surface of the second conductive layer 22 away from the first glue film layer 21, a second connection hole 521 is disposed on the third dielectric layer 52, and a conductive medium 4 for connecting the metal layer 511 in the third conductive layer and the metal layer 221 in the second conductive layer is disposed in the second connection hole 521.

In the embodiment of the present invention, the third conductive layer 51 may be configured as a circuit layer or a metal layer; when the third conductive layer 51 is a circuit layer, in the process of laminating the multilayer boards, gaps between the metal layers 511 in each third conductive layer 51 are filled with the adjacent first insulating protection layers 6, so as to form the insulating layers 512 in the third conductive layers; therefore, when the second conductive layer 2 is a wiring layer, the third conductive layer 51 is formed by a metal layer 511 of a plurality of third conductive layers and an insulating layer 512 of a plurality of third conductive layers, and the metal layer 511 of the third conductive layers and the insulating layer 512 of the third conductive layers are alternately connected so that the metal layers 511 of the respective third conductive layers are independent of each other, as shown in fig. 8. The number of the metal layers 511 in the third conductive layer may be set according to actual situations, and preferably, in this embodiment, the number of the metal layers 511 in the third conductive layer is multiple, and the metal layers 511 in each of the third conductive layers are independent of each other.

In the embodiment of the present invention, the thickness of the third conductive layer 51 is 0.1 μm to 9 μm; preferably, the thickness of the third conductive layer 51 is 0.2 μm to 5 μm. In addition, the material of the metal layer 511 in the third conductive layer may be set according to actual use. In order to simplify the design and structure and reduce the cost, the metal layer 511 in the third conductive layer in this embodiment is made of any one or more materials of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold.

It should be noted that the metal layer 511 in the third conductive layer in the drawings of this embodiment may be a single-layer structure or a multi-layer structure; specifically, the multilayer structure may be formed by forming one or more of metals other than the host on the surface of the host using one or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold as a host, and then using one or more of electroplating, electroless plating, physical vapor deposition, and chemical vapor deposition. In this embodiment, the metal layer 511 in the third conductive layer is preferably a multi-layer structure mainly made of copper, and one or more metals of nickel, chromium, silver and gold are formed on the surface of copper, because the metal layer 511 in the third conductive layer made of copper alone is easily oxidized or abraded, and the nickel, chromium, silver and gold formed on the surface of copper can improve the corrosion resistance and wear resistance of the metal layer 511 in the third conductive layer, and further can improve the conductive performance of the multilayer board, and prolong the service life of the multilayer board. In addition, the third conductive layer 51 of the present embodiment can be provided in a grid shape, a foam shape, etc. according to the actual production and application requirements.

In the embodiment of the present invention, the conductive medium 4 is attached to the hole wall of the second connection hole 521, thereby forming a conductive hole. Of course, an operator may also choose to fill the entire second connection hole 521 with the conductive medium 4, that is, no conductive hole is formed, so as to prevent the etching solution from entering the conductive hole, and protect the conductive medium 4 in the second connection hole 521 from being etched, thereby ensuring the conduction inside the multilayer board.

In the embodiment of the present invention, the number and the positions of the second connection holes 521 formed in the third dielectric layer 52 may be set according to actual use conditions. It is understood that the second connection hole 521 may be disposed at a position corresponding to the metal layer 511 in the third conductive layer and the metal layer 221 in the second conductive layer, where electrical connection is required, so that the metal layer 511 in the third conductive layer is electrically connected to the corresponding metal layer 221 in the second conductive layer through the conductive medium 4 disposed in the second connection hole 521.

In the embodiment of the present invention, the type of the third dielectric layer 52 may be set according to actual use conditions. Specifically, the third dielectric layer 52 may be a single dielectric layer, such as a glue film layer or a resin film layer; the third dielectric layer 52 may also be provided as a composite dielectric layer, such as a composite dielectric layer including PI (Polyimide) and a binder.

As shown in fig. 8, in order to protect the multilayer board, the multilayer board of this embodiment further includes a first insulating protective layer 6, where the first insulating protective layer 6 is disposed on a surface of the third conductive layer 51 away from the third dielectric layer 52. By providing the first insulating protection layer 6, a good isolation protection effect is achieved, and the phenomenon that the third conductive layer 51 is interfered when contacting with other conductors is effectively avoided. The structure of the first insulating protection layer 6 can refer to the first embodiment, and will not be described herein.

In addition, it should be noted that the number of the third circuit substrates 5 in this embodiment may be set according to actual use requirements, and therefore, other embodiments that adjust the number of the third circuit substrates 5 are also within the protection scope of the present invention. In addition, other structures and working principles of the multilayer board of the present embodiment are the same as those of the first and third embodiments, and are not further described herein.

EXAMPLE five

Referring to fig. 9 and 10, the multilayer board in this embodiment is different from the first, second, and fourth embodiments in that the first circuit substrate 1 further includes a fourth conductive layer 15 and a fourth dielectric layer 16, and the fourth conductive layer 15 and the fourth dielectric layer 16 are sequentially disposed on a surface of the base film layer 11 away from the first conductive layer 12.

In the embodiment of the present invention, the fourth conductive layer 15 may be configured as a circuit layer or a metal layer; when the fourth conductive layer 15 is a circuit layer, in the process of laminating the multilayer boards, gaps between the metal layers 151 in each fourth conductive layer 15 are filled with the adjacent fourth dielectric layers 16, so as to form the insulating layers 152 in the fourth conductive layers; therefore, when the fourth conductive layer 15 is a wiring layer, the fourth conductive layer 15 is composed of a plurality of metal layers 151 in the fourth conductive layer and a plurality of insulating layers 152 in the fourth conductive layer, and the metal layers 151 in the fourth conductive layer and the insulating layers 152 in the fourth conductive layer are alternately connected such that the metal layers 151 in the respective fourth conductive layers are independent of each other, as shown in fig. 9. The number of the metal layers 151 in the fourth conductive layer may be set according to practical situations, and preferably, the number of the metal layers 151 in the fourth conductive layer is multiple, and the metal layers 151 in each fourth conductive layer are independent of each other.

In the embodiment of the present invention, the thickness of the fourth conductive layer 15 is 0.1 μm to 9 μm; preferably, the thickness of the fourth conductive layer 15 is 0.2 μm to 5 μm. In addition, the material of the metal layer 511 in the fourth conductive layer may be set according to the actual use situation, and preferably, the metal layer 511 in the fourth conductive layer in this embodiment is made of any one or more materials of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold.

It should be noted that the metal layer 151 in the fourth conductive layer in the drawings of this embodiment may have a single-layer structure or a multi-layer structure; specifically, the multilayer structure may be formed by forming one or more of metals other than the host on the surface of the host using one or more of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold as a host, and then using one or more of electroplating, electroless plating, physical vapor deposition, and chemical vapor deposition. In this embodiment, the metal layer 151 in the fourth conductive layer is preferably a multilayer structure mainly made of copper, and one or more metals of nickel, chromium, silver and gold are formed on the surface of copper, because the metal layer 151 in the fourth conductive layer made of copper alone is easily oxidized or abraded, and the nickel, chromium, silver and gold formed on the surface of copper can improve the corrosion resistance and wear resistance of the metal layer 151 in the fourth conductive layer, and further improve the conductive performance of the multilayer board, and prolong the service life of the multilayer board. In addition, the fourth conductive layer of the present embodiment can be arranged in a grid shape, a foaming shape, etc. according to the requirements of actual production and application.

As shown in fig. 10, in a preferred embodiment, a plurality of third connection holes 111 are formed in the base film layer 11 at intervals, and a conductive medium 4 for connecting the metal layer 121 in the first conductive layer and the metal layer 151 in the fourth conductive layer is disposed in the third connection holes 111.

In the embodiment of the present invention, the conductive medium 4 is attached to the hole wall of the third connection hole 111, so as to form a conductive hole; specifically, the third connection hole 111 may be drilled in the base film layer 11 by a drilling technique, and then a conductive medium may be plated on the insulated hole wall by electroless plating and electroplating, thereby forming a conductive hole. Of course, the operator may also choose to fill the entire third connection hole 111 with the conductive medium 4, i.e. not form a conductive hole, which is to prevent the etching solution from entering the conductive hole and protect the dielectric medium 4 from being etched, thereby ensuring the conduction inside the multilayer board.

It should be noted that, in the process of forming the conductive hole, when the multilayer board becomes thicker and the hole diameter of the drilled hole decreases, it is more and more difficult for chemical liquid medicine to enter the deep part of the drilled hole, although the electroplating equipment can make the liquid medicine enter the center of the drilled hole by using methods such as vibration and pressurization, the central plating layer is still inevitably thinner due to concentration difference; at this moment, the phenomenon of micro open circuit of a drilling layer can occur, and when voltage is increased or the multilayer board is impacted under various severe conditions, the phenomenon that the circuit of the multilayer board is broken and the multilayer board cannot work normally is easily caused. In the multilayer board in the embodiment, since the conductive holes are only formed in the base film layer 11, drilling on the thick multilayer board is effectively avoided, and thus the problem of circuit breaking of the multilayer board is effectively avoided, and normal operation of the multilayer board is ensured.

In addition, in the embodiment of the present invention, the number of the third connection holes 111 disposed on the base film layer 11 may be set according to actual use conditions. It is understood that the third connection hole 111 may be disposed on the base film layer 11 at a position corresponding to the metal layer 121 in the first conductive layer and the metal layer 151 in the fourth conductive layer, which are required to be electrically connected, so that the metal layer 121 in the first conductive layer is electrically connected to the metal layer 151 in the fourth conductive layer through the conductive medium 4 in the third connection hole 111.

In the embodiment of the present invention, the type of the fourth dielectric layer 16 may be set according to actual use conditions. Specifically, the fourth dielectric layer 16 may be a single dielectric layer, such as a glue film layer or a resin film layer; the fourth dielectric layer 16 may also be configured as a composite dielectric layer, such as a composite dielectric layer including PI (Polyimide) and a binder.

In addition, in the embodiment of the present invention, the first circuit substrate 1 may further include at least one RCC board, one RCC board is disposed on a surface of the first dielectric layer 13 away from the first conductive layer 12, and/or another RCC board is disposed on a surface of the fourth dielectric layer 16 away from the fourth conductive layer 15.

Specifically, the RCC board includes a copper layer and a second glue film layer, which are stacked, and when one RCC board is disposed on a surface of the first dielectric layer 13 away from the first conductive layer 12, the second glue film layer of the RCC board is disposed on a surface of the first dielectric layer 13 away from the first conductive layer 12, and the copper layer is electrically connected to the first conductive layer 12 through a through hole, a blind hole, or a buried hole; the second circuit substrate 2 is disposed on one side of the first circuit substrate 1 close to the RCC board, specifically: the first glue film layer 21 of the second circuit substrate 2 is arranged on one surface of the copper layer far away from the second glue film layer, a first protruding structure 223 is arranged on one surface, facing the first glue film layer 21, of the metal layer 221 in the second conducting layer, and the first protruding structure 223 pierces through the first glue film layer 21 so as to be electrically connected with the copper layer. In addition, when another RCC board is disposed on a surface of the fourth dielectric layer 16 away from the fourth conductive layer 15, the second adhesive film layer of the RCC board is disposed on a surface of the fourth dielectric layer 16 away from the fourth conductive layer 15. Other structures and working principles of the multilayer board of this embodiment are the same as those of the first, second, and fourth embodiments, and further description is omitted here.

EXAMPLE six

Referring to fig. 11 and 12, the multilayer board in this embodiment is different from the fifth embodiment in that at least one third via hole 161 is formed in the fourth dielectric layer 16 to expose the metal layer 151 in the fourth conductive layer;

the second circuit substrates 2 are also arranged on one side of the first circuit substrate 1 close to the fourth dielectric layer 16, and a plurality of the second circuit substrates 2 are symmetrically arranged on two sides of the first circuit substrate 1 or a plurality of the second circuit substrates 2 are asymmetrically arranged on two sides of the first circuit substrate 1; the second dielectric layer 21 of the second circuit substrate 2 is disposed on a surface of the first dielectric layer 16 away from the first conductive layer 12, and the first protrusion 223 pierces the first glue film layer 21 of the second circuit substrate 2 and penetrates through the third through hole 161 to connect with the metal layer 151 of the fourth conductive layer.

The number of the second circuit boards 2 disposed on one side of the first dielectric layer 13 of the first circuit board 1 and the number of the second circuit boards 2 disposed on one side of the fourth dielectric layer 16 of the first circuit board 1 may be set according to actual use requirements. Specifically, as shown in fig. 11, when the number of the second circuit boards 2 disposed on one side of the first dielectric layer 13 of the first circuit board 1 is equal to the number of the second circuit boards 2 disposed on one side of the fourth dielectric layer 16 of the first circuit board 1, the plurality of second circuit boards 2 are symmetrically disposed on both sides of the first circuit board 1 with the first circuit board 1 as a center. As can be appreciated, in the multilayer board, the second circuit substrate 2 close to the first dielectric layer 13 of the first circuit substrate 1, the first bump structure 223 of the second circuit substrate 2 pierces the first glue film layer 21 of the second circuit substrate 2 and connects with the metal layer 121 in the first conductive layer through the first through hole 131; and close to the second circuit substrate 2 of the fourth dielectric layer 16 of the first circuit substrate 1, the first protrusion structure 223 of the second circuit substrate 2 pierces through the first glue film layer 21 of the second circuit substrate 2, and passes through the third through hole 161 to be connected with the metal layer 151 in the fourth conductive layer.

As shown in fig. 12, when the number of the second circuit boards 2 disposed on one side of the first dielectric layer 13 of the first circuit board 1 is not equal to the number of the second circuit boards 2 disposed on one side of the fourth dielectric layer 16 of the first circuit board 1, the plurality of second circuit boards 2 are asymmetrically disposed on both sides of the first circuit board 1.

When the number of the second circuit substrates 2 arranged on the side of the first circuit substrate 1 close to the first dielectric layer 13 is multiple, and/or when the number of the second circuit substrates 2 arranged on the side of the first circuit substrate 1 close to the fourth dielectric layer 16 is multiple, a second dielectric layer 3 is arranged between any two adjacent second circuit substrates 2, and each second dielectric layer 3 is provided with at least one second through hole 31; in any two adjacent second circuit substrates 2, the first protruding structure 223 of the second circuit substrate 2 far away from the first circuit substrate 1 pierces through the first adhesive film layer 21 and passes through the second through hole 31, so as to connect with the metal layer 221 in the second conductive layer of the second circuit substrate 2 close to the first circuit substrate 1.

Referring to fig. 11 and 12, in order to protect the multilayer board, the multilayer board in this embodiment further includes a second insulating protective layer 7, and the second insulating protective layer 7 is disposed on the outermost second circuit substrate 2 on the side of the fourth dielectric layer 16 of the first circuit substrate 1; specifically, the second insulating protection layer 7 is disposed on a surface of the first adhesive film layer 21 of the second circuit substrate 2 away from the second conductive layer 22 of the second circuit substrate 2. The second insulating protection layer 7 is arranged to play a good role in isolation and protection, and effectively avoid the phenomenon that the second conductive layer 22 of the second circuit substrate 2 at the outermost layer on one side of the fourth dielectric layer 16 of the first circuit substrate 1 is in contact with other electric conductors to cause interference.

Wherein the thickness of the second insulating protection layer 7 is 1-25 μm; preferably, the second insulating and protecting layer 9 has a thickness of 3 μm to 20 μm. In addition, the second insulating and protecting layer 7 may be a PPS film layer, a PEN film layer, a PET film layer, a PI film layer, a PA film layer, a film layer formed after curing epoxy resin ink, a film layer formed after curing polyurethane ink, a film layer formed after curing modified acrylic resin, or a film layer formed after curing polyimide resin. Of course, the type of the second insulating and protecting layer 7 can be set according to the actual use requirement, and only the requirement of ensuring that the second insulating and protecting layer 7 can play a role of insulation protection in the multilayer board is met. In addition, other structures and working principles of the multilayer board of this embodiment are the same as those of the fifth embodiment, and further description is omitted here.

EXAMPLE seven

As shown in fig. 13, the multilayer board in this embodiment is different from the sixth embodiment in that a third circuit substrate 5 is further provided on the second circuit substrate 2 on the side of the fourth dielectric layer 16 of the first circuit substrate 1. Specifically, the third circuit substrate 5 includes a third conductive layer 51 and a third dielectric layer 52, which are stacked, the third dielectric layer 52 is disposed on a surface of the second conductive layer 22 of the second circuit substrate 2, which is far away from the first glue film layer 21 of the second circuit substrate 2, a second connection hole 521 is disposed on the third dielectric layer 52, and a conductive medium 4 for connecting the metal layer 511 in the third conductive layer and the metal layer 221 in the second conductive layer of the second circuit substrate 2 is disposed in the second connection hole 521.

In the embodiment of the present invention, the specific structure of the third circuit substrate 5 can refer to embodiment four, and will not be further described herein.

As shown in fig. 13, when the outermost layer on the side of the fourth dielectric layer 16 of the first circuit substrate 1 is the third circuit substrate 5, in order to protect the multilayer board, the multilayer board in this embodiment further includes a second insulating protection layer 7, and the second insulating protection layer 7 is disposed on the outermost layer on the side of the fourth dielectric layer 16 of the first circuit substrate 1 on the third circuit substrate 5; specifically, the two insulating protective layers 7 are disposed on a surface of the third conductive layer 51 of the third circuit substrate 5 away from the third dielectric layer 52 of the third circuit substrate 5. The second insulating protection layer 7 is arranged to play a good role in isolation and protection, and effectively avoid the phenomenon that the third conductive layer 51 of the third circuit substrate 5, which is positioned at the outermost layer of one side of the fourth dielectric layer 16 of the first circuit substrate 1, is in contact with other electric conductors to cause interference. The specific structure of the second insulating protection layer 7 may refer to embodiment six, and will not be described herein.

In addition, it should be noted that the number of the third circuit substrates 5 in this embodiment may be set according to actual use requirements, and therefore, other embodiments that adjust the number of the third circuit substrates 5 are also within the protection scope of the present invention. In addition, other structures and working principles of the multilayer board of this embodiment are the same as those of embodiment six, and further description is not given here.

Example eight

As shown in fig. 14, a schematic flow chart of a method for manufacturing a multi-layer board according to an embodiment of the present invention is suitable for manufacturing the multi-layer board according to the first embodiment, and includes the following steps:

s1, forming a second conductive layer; the second conductive layer comprises a metal layer, and a first protruding structure is formed on one surface of the metal layer in the second conductive layer;

in an embodiment of the present invention, one of the modes of forming the second conductive layer specifically includes:

s11, coating a first insulation protective layer on the release film;

specifically, ink is coated on one side of a release film, thereby forming a first insulating protection layer;

wherein the release film is a PET (Polyethylene terephthalate) release film, the thickness of the release film is 25-150 μm, and the width of the release film is 100-1000 mm; the ink is made of any one of epoxy resin ink, polyurethane ink or polyimide; the first insulating protective layer is formed to have a thickness of 1 μm to 25 μm, and preferably to have a thickness of 3 μm to 20 μm.

S12, forming a second conductive layer on one surface, far away from the release film, of the first insulating protection layer;

specifically, a second conductive layer is formed on a side of the first insulating protection layer away from the release film by using any one of or any combination of Chemical plating, PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), evaporation, sputtering, or electroplating.

In an embodiment of the present invention, another way of forming the second conductive layer specifically includes the steps of:

s13, forming a second strippable conducting layer with a carrier;

s14, attaching the second peelable conductive layer to a protective transfer layer, thereby transferring the second conductive layer to the protective transfer layer;

s15, tearing off the carrier, and forming a first insulating protective layer on the surface of the second conductive layer;

specifically, after the carrier is torn off, ink is coated on one side of the second conductive layer, which is far away from the protective transfer layer; after the ink is cured, forming the first insulating protection layer on one side, away from the protective transfer layer, of the second conductive layer; wherein the material of the printing ink is any one of epoxy resin printing ink, polyurethane printing ink or polyimide; the first insulating protective layer is formed to have a thickness of 1 μm to 25 μm, and preferably to have a thickness of 3 μm to 20 μm.

And S16, tearing off the protective transfer layer.

In an embodiment of the present invention, the first protruding structure on the metal layer in the second conductive layer is formed by performing a roughening process on the metal layer in the second conductive layer;

specifically, one of the methods for performing roughening treatment on the metal layer in the second conductive layer specifically is: coarsening at least one surface of the metal layer in the second conducting layer by adopting a circuit board microetching mode, then curing, and finally passivating, thereby forming a first convex structure on the metal layer in the second conducting layer;

in addition, another way of performing roughening treatment on the metal layer in the second conductive layer is specifically as follows: coarsening at least one surface of the metal layer in the second conducting layer by adopting a circuit board microetching method, and then passivating, thereby forming a first bulge structure on the metal layer in the second conducting layer; wherein the height of the first bump structure is 0.2 μm to 30 μm; preferably, the height of the first bump structure is 0.5 μm to 5 μm.

S2, forming a first adhesive film layer on one surface of the second conductive layer, where the first protrusion structure is formed, so as to obtain a second circuit substrate;

specifically, in one embodiment, a first adhesive film layer is formed on a surface of the second conductive layer on which the first bump structure is formed, so as to obtain a second conductive substrate, specifically:

and coating a first adhesive film layer on a release film, and transferring the first adhesive film layer to the second conductive layer in a pressing manner to form one surface with the first protrusion structure.

In another embodiment, a first adhesive film layer is formed on a surface of the second conductive layer on which the first bump structure is formed, so as to obtain a second circuit substrate, specifically:

and coating a first adhesive film layer on one surface of the second conductive layer on which the first protrusion structure is formed.

Specifically, a modified epoxy resin, a modified acrylic resin, a modified rubber, and a modified thermoplastic polyimide are applied to the surface of the second conductive layer on which the first bump structure is formed, and then dried, so that the first adhesive film layer is formed on the surface of the second conductive layer on which the first bump structure is formed, thereby obtaining the second circuit board;

wherein the thickness of the first film adhesive layer is 1-25 μm; preferably, the thickness of the first adhesive film layer is 1 μm to 8 μm.

S3, forming a first conductive layer, wherein the first conductive layer comprises a metal layer;

the forming method of the first conductive layer may specifically refer to the forming method of the second conductive layer, which is not described herein in further detail.

S4, forming a first dielectric layer on one side of the first conductive layer, and forming a first via hole on the first dielectric layer to expose the metal layer in the first conductive layer, thereby obtaining a first circuit substrate;

the number of the first through holes can be set according to actual use conditions.

And S5, pressing the obtained surface of the second circuit substrate provided with the first adhesive film layer to the surface of the first circuit substrate provided with the first dielectric layer, so that the first protruding structure pierces through the first adhesive film layer and penetrates through the first through hole to be connected with the metal layer in the first conductive layer.

Specifically, the side of the second circuit substrate provided with the first adhesive film layer is pressed onto the side of the first circuit substrate provided with the first dielectric layer by hot pressing.

In addition, it should be noted that the method for manufacturing the circuit board provided in this embodiment is only an example of manufacturing the multilayer board described in the first embodiment, and the multilayer board described in the first embodiment may also be manufactured by other manufacturing methods, for example, the first circuit substrate may be formed first, then the second circuit substrate is formed, and finally the first circuit substrate and the second circuit substrate are pressed together. In addition, the manufacturing method of the multilayer board described in embodiments two to seven may specifically refer to the manufacturing method of the circuit board provided in this embodiment, and further details are not described herein.

The foregoing is a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations are also considered as the protection scope of the present invention.

Claims

1. A multilayer board, comprising a first circuit substrate and a second circuit substrate;

2. The multilayer board according to claim 1, wherein the number of the second circuit substrates provided on the side of the first circuit substrate adjacent to the first dielectric layer is plural; a second dielectric layer is arranged between any two adjacent second circuit substrates, and each second dielectric layer is provided with at least one second through hole; in any two adjacent second circuit substrates, the first protruding structure of the second circuit substrate far away from the first circuit substrate pierces through the first adhesive film layer and penetrates through the second through hole, so as to be connected with the metal layer in the second conducting layer of the second circuit substrate close to the first circuit substrate.

3. The multilayer board according to claim 1, wherein the number of the first circuit substrates is plural, and the plural first circuit substrates are sequentially stacked; and any two adjacent first circuit substrates are provided with first connecting holes, and conductive media for connecting the metal layers of the first conductive layers in the two adjacent first circuit substrates are arranged in the first connecting holes.

4. The multilayer board of claim 1, further comprising a third circuit substrate, wherein the third circuit substrate comprises a third conductive layer and a third dielectric layer stacked on each other, the third dielectric layer is disposed on a surface of the second conductive layer away from the first adhesive film layer, a second connection hole is disposed on the third dielectric layer, and a conductive medium for connecting the metal layer in the third conductive layer and the metal layer in the second conductive layer is disposed in the second connection hole.

5. The multilayer board of any one of claims 1-4, wherein the first circuit substrate further comprises a fourth conductive layer and a fourth dielectric layer, the fourth conductive layer and the fourth dielectric layer being disposed in sequence on the other side of the base film layer.

6. The multilayer board of claim 5, wherein the fourth dielectric layer is provided with at least one third via hole exposing the metal layer in the fourth conductive layer;

7. The multilayer board according to claim 6, wherein the number of the second circuit substrates provided on the side of the first circuit substrate adjacent to the fourth dielectric layer is plural; a second dielectric layer is arranged between any two adjacent second circuit substrates, and each second dielectric layer is provided with at least one second through hole; in any two adjacent second circuit substrates, the first protruding structure of the second circuit substrate far away from the first circuit substrate pierces through the first adhesive film layer and penetrates through the second through hole, so as to be connected with the metal layer in the second conducting layer of the second circuit substrate close to the first circuit substrate.

8. The multilayer board of claim 5, wherein the base film layer is provided with a plurality of third connection holes spaced apart from each other, and the third connection holes are provided therein with a conductive medium for connecting the metal layer of the first conductive layer and the metal layer of the fourth conductive layer.

9. The multilayer plate according to any one of claims 1 to 4, characterized in that the metal layer in the second conductive layer comprises a first surface, which is a non-flat surface, said first surface constituting said first raised structure; or the like, or, alternatively,

10. The multilayer plate of claim 9, wherein the height of the first bump structures is 0.2 μm to 30 μm.

11. The multilayer sheet according to any one of claims 1 to 4, wherein the first adhesive layer comprises an adhesive layer free of conductive particles.