CN114758881A - Preparation method of chip inductor - Google Patents
Preparation method of chip inductor Download PDFInfo
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- CN114758881A CN114758881A CN202210406438.4A CN202210406438A CN114758881A CN 114758881 A CN114758881 A CN 114758881A CN 202210406438 A CN202210406438 A CN 202210406438A CN 114758881 A CN114758881 A CN 114758881A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/005—Impregnating or encapsulating
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K3/00—Tools, devices, or special appurtenances for soldering, e.g. brazing, or unsoldering, not specially adapted for particular methods
- B23K3/08—Auxiliary devices therefor
- B23K3/082—Flux dispensers; Apparatus for applying flux
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
- H01F41/06—Coil winding
- H01F41/061—Winding flat conductive wires or sheets
Abstract
The invention provides a preparation method of a chip inductor, which relates to the technical field of inductor manufacture and comprises the following steps: spraying an insulating resin protective material on the surface of the prepared inductance semi-finished product; stripping the insulating resin protective material and the copper wire paint skin at the copper electrode of the inductance semi-finished product; coating a layer of soldering flux on the copper electrode; and completely immersing the electrode of the surface part of the inductor semi-finished product, which protrudes out of the substrate, into the conductive material in the solder bath, taking out the electrode after soaking for a certain time, starting a high-temperature and high-pressure air gun while taking out the electrode, leveling the electrode material on the surface of the inductor semi-finished product, covering a layer of electrode material on the scaling powder, leading out the electrode, and obtaining the chip inductor. The electrode is manufactured in a hot air leveling mode after dip-coating of the electrode material, the electrode is simple and convenient, the production cost is effectively reduced, the production efficiency is greatly improved, a more uniform conductive material layer can be obtained, the welding strength of an inductance product is effectively improved, and adverse conditions such as short circuit and insufficient soldering are avoided.
Description
Technical Field
The invention relates to the technical field of inductor manufacturing, in particular to a method for preparing a chip inductor.
Background
Chip inductors play an important role in circuits, mainly for energy storage, power transmission, signal processing, filtering, electromagnetic compatibility (EMC), etc. However, with the development of electronic product technology, new requirements are continuously proposed for the circuit design, which not only needs to satisfy the requirements of high frequency, high efficiency, low temperature rise, low noise, interference resistance, but also needs to satisfy the requirements of environmental protection, small size, high safety factor, etc., especially for chip inductors in the circuit, the huge market pressure of increasingly complex circuits integrated into a narrower circuit board space leads to the increasing demand of better performance, excellent competitiveness, and more delicate terminal components while pursuing small size, planarization, and light weight.
The conventional power inductor is usually manufactured by winding a coil on a prefabricated magnetic core, filling and covering the coil with a magnetic material, penetrating the head end and the tail end of the coil out of electrode pins of the magnetic material to form the inductor, and finally performing press forming to obtain an integrated inductor, but the integrated inductor still has the following defects:
firstly, the paint skin on the surface of a copper wire is usually stripped in the manufacturing process of the electrode in the current inductance technology, but the sectional area of a round copper wire is small, paint is often stripped at the edge of the copper electrode according to the size of an electrode plate, powder materials are exposed at the paint stripping position, an electroplated copper layer is needed to be used as a substrate, then nickel tin is electroplated on the surface of the copper, and the complete electrode is prepared.
Secondly, the existing coil is formed by winding round wires, under the condition of limited inductor size, because the round wires can not densify and arrange wires, the Direct Current Resistance (DCR) of a pressed product is large, the heat generated in the using process can influence the inductance and even damage the product, meanwhile, because the wire and the wire have larger gaps, the limited winding space can not be efficiently utilized, under the development trend of miniaturization and intensification of electronic devices, the overall layout of the circuit is severely restricted by overlarge volume and overhigh space occupancy rate, and the simplified design of the circuit is influenced.
In addition, when powder is subjected to hot press molding, great molding pressure needs to be provided, so that the coil is easy to deform and break, the yield of the inductor is reduced, and the performance and the use stability of the inductor are seriously influenced.
Therefore, further improvement is needed to overcome the defects of the current inductor preparation method.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a preparation method of a chip inductor, which comprises the following steps:
step S1, preparing a semi-finished inductor product by prefabricating a soft magnetic alloy blank, winding, hot pressing and baking the soft magnetic alloy powder and the enameled wire, and spraying an insulating resin protective material on the surface of the semi-finished inductor product;
Step S2, preparing an inner electrode: stripping the insulating resin protective material and the copper wire paint skin at the copper electrode of the semi-finished inductor prepared in the step S1;
step S3, surface pretreatment: coating a layer of soldering flux on the copper electrode;
step S4, preparing an external electrode: and completely immersing the electrode on the surface part of the convex substrate of the semi-finished inductor into a liquid electrode material in a solder tank, taking out the electrode after soaking for a certain time, starting a high-temperature and high-pressure air gun while taking out the electrode, leveling the electrode material on the surface of the semi-finished inductor, uniformly covering a layer of the electrode material on the soldering flux, leading out the electrode and obtaining a chip inductor finished product.
Preferably, the step S1 includes:
step S11, prefabricating a T-shaped blank: soft magnetic alloy powder is put into a T-shaped die and is pressed and formed, and then demoulding and baking are carried out to obtain a T-shaped green body;
step S12, winding: winding a flat enameled wire at the columnar bulge of the T-shaped blank prepared in the step S11 in a vertical winding mode, bending pins at two ends, and attaching the flat surface of the flat enameled wire to the flat bottom surface of the T-shaped blank to obtain a wound T-shaped blank;
Step S13, prefabricating a cup-shaped blank: loading soft magnetic alloy powder into a cup-shaped mold and performing compression molding to obtain a cup-shaped blank, wherein the cup-shaped blank is not demolded and enters step S14 along with the cup-shaped mold;
step S14, hot press molding: and (4) placing the cup-shaped blank prepared in the step (S13) in a mold cavity along with the cup-shaped mold with the opening facing upwards, implanting the cylindrical protrusion of the T-shaped blank of the winding prepared in the step (S12) into the opening of the cup-shaped blank with the cylindrical protrusion facing downwards, performing hot press molding, and then demolding, baking and curing to obtain the semi-finished inductor.
Preferably, the soft magnetic alloy powder in the steps S11 and S13 is prepared by mixing, granulating, drying and screening soft magnetic alloy powder, a binder and a lubricant.
Preferably, the soft magnetic alloy powder comprises at least one of amorphous soft magnetic alloy powder, nanocrystalline soft magnetic alloy powder, iron-silicon-aluminum alloy powder, iron-silicon-chromium alloy powder, iron-silicon-nickel alloy powder, iron-silicon-aluminum-nickel alloy powder, iron-nickel-aluminum alloy powder and carbonyl iron powder;
the binder comprises at least one of epoxy resin, polyurethane, silicone resin, organic silicon resin, amino resin, polyimide, phenolic resin, cyanate ester and acrylic resin;
The lubricant comprises at least one of zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, graphite powder and graphene.
Preferably, the conductive material in step S4 is a metal material or an alloy material.
Preferably, the electrode material is one of gold, silver, nickel, tin, copper-tin alloy, nickel-chromium alloy and tin-lead alloy.
Preferably, in the step S4, the temperature in the solder bath is 240 ℃ to 300 ℃, the temperature of the high-temperature and high-pressure air gun is 300 ℃ to 500 ℃, and the pressure is 0.5Mpa to 0.8 Mpa.
Preferably, the insulating resin protective material includes at least one of mica, epoxy resin, silicone resin, phenol resin, glass-reinforced polyester, silicone resin, polyester resin, and silicone resin.
Preferably, in the step S11 and the step S13, the T-shaped blank and the cup-shaped blank are obtained by cold press molding the soft magnetic alloy powder.
The technical scheme has the following advantages or beneficial effects:
1) the electrode is manufactured by dip-coating the liquid electrode material and then leveling the electrode by hot air, the whole process is simple and convenient, the production cost can be effectively reduced, the production efficiency is greatly improved, a more uniform conductive material layer can be obtained, the welding strength of an inductance product is effectively improved, and the occurrence of poor conditions such as short circuit, insufficient solder and the like is avoided;
2) The coil is wound in an upright winding mode of the flat enameled wire, the flat enameled wire has a better sectional area compared with a round wire, the slot fullness rate of an inductor structure is effectively improved, the direct current resistance of the coil is reduced, the working power loss of a product is further reduced, the size of the coil can be reduced, the occupied space of a subsequent inductor can be smaller, the integral layout of a circuit is facilitated, and the circuit design is more precise and simplified;
3) the deformation space of the coil can be effectively limited by combining the prefabricated T-shaped blank body and the prefabricated cup-shaped blank body, and the coil is prevented from being exposed, deformed and even broken in the hot pressing process, so that the shielding performance and the inductance value of the inductor are ensured, and the comprehensive performance of the product is effectively improved.
Drawings
Fig. 1 is a schematic flow chart of a method for manufacturing a chip inductor according to a preferred embodiment of the present invention;
FIG. 2 is a sub-flowchart of step S1 according to the preferred embodiment of the present invention;
FIG. 3 is a schematic view showing the structure of a T-shaped wound body according to example 1;
FIG. 4 is a schematic view showing the structure of a cup-shaped body in example 1;
fig. 5 is a schematic cross-sectional view of a chip inductor blank in a cavity during hot press molding in example 1;
FIG. 6 is a schematic view of a semi-finished inductor in example 1;
Fig. 7 is a schematic cross-sectional view of an inductor blank in a cavity during hot press molding in comparative example 2.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.
The invention provides a method for manufacturing a chip inductor, aiming at solving the problems of low slot filling factor, large direct current resistance, complex electrode manufacturing process and the like of an inductor structure in the prior art, and in a preferred embodiment of the invention, based on the problems in the prior art, the method for manufacturing the chip inductor is provided, as shown in fig. 1, and comprises the following steps:
Step S1, preparing a semi-finished product: preparing a soft magnetic alloy powder material and an enameled wire into an inductance semi-finished product by prefabricating a soft magnetic alloy blank, winding, hot pressing and baking, and spraying an insulating resin protective material on the surface of the inductance semi-finished product;
step S2, preparing an inner electrode: stripping the insulating resin protective material and the copper wire paint skin at the copper electrode of the inductance semi-finished product prepared in the step S1;
step S3, surface pretreatment: coating a layer of soldering flux on the copper electrode;
step S4, outer electrode preparation: and completely immersing the electrode protruding out of the surface of the substrate of the semi-finished inductor into a liquid electrode material in a solder tank, taking out after soaking for a certain time, starting a high-temperature and high-pressure air gun while taking out, leveling the electrode material on the surface of the semi-finished inductor, uniformly covering a layer of electrode material on the position of soldering flux, leading out the electrode and obtaining a finished chip inductor.
In a preferred embodiment of the present invention, the electrode material in step S4 is one of gold, silver, nickel, tin, copper-tin alloy, nickel-chromium alloy, and tin-lead alloy.
In a preferred embodiment of the present invention, in step S4, the temperature in the solder bath is 240 ℃ to 300 ℃, the soaking time of the inductor semi-finished product in the solder bath is preferably 1S to 5S, the temperature of the high-temperature and high-pressure air gun is 300 ℃ to 500 ℃, the pressure is 0.5MPa to 0.8MPa, and the layer thickness of the electrode material covered on the soldering flux is preferably 10 μm to 25 μm.
In a preferred embodiment of the present invention, the insulating resin protective material includes at least one of mica, epoxy resin, silicone resin, phenolic resin, glass reinforced polyester, silicone resin, polyester resin, and silicone resin.
In the preferred embodiment of the present invention, in step S2, a paint stripping device selects laser or mechanical polishing to strip the insulating resin protective material and the copper wire paint skin at the copper electrode of the inductor semi-finished product.
In a preferred embodiment of the present invention, as shown in fig. 2, step S1 includes:
step S11, prefabricating a T-shaped blank: soft magnetic alloy powder is put into a T-shaped die and is pressed and formed, and then demoulding and baking are carried out to obtain a T-shaped green body;
step S12, winding: winding the flat enameled wire at the columnar bulge of the T-shaped blank prepared in the step S11 in a vertical winding mode, bending pins at two ends, and attaching the flat surface of the flat enameled wire to the flat bottom surface of the T-shaped blank to obtain a wound T-shaped blank;
step S13, prefabricating a cup-shaped blank: filling the soft magnetic alloy powder into a cup-shaped mold and pressing and molding to obtain a cup-shaped blank, wherein the step S14 is carried out along with the cup-shaped mold without demolding;
step S14, hot press molding: and (4) placing the cup-shaped blank prepared in the step (S13) into a mold cavity along with the cup-shaped mold with the opening facing upwards, implanting the cylindrical bulge of the T-shaped wound blank prepared in the step (S12) into the opening of the cup-shaped blank with the cylindrical bulge facing downwards, performing hot press molding, and then demolding, baking and curing to obtain the semi-finished inductor.
Specifically, in this embodiment, in step S11, the soft magnetic alloy powder is loaded into a T-shaped mold, and then cold press molding is performed by using a high-precision servo molding press, and then demolding and baking are performed to obtain a T-shaped green body. In step S12, a precise vertical winding machine is used to precisely wind a flat enameled wire on the columnar protrusion of the T-shaped blank, wherein the wire width of the flat enameled wire is preferably 0.03mm to 2 mm. In step S13, the soft magnetic alloy powder is loaded into a cup-shaped mold, and then cold press molding is performed using a high-precision servo molding press to obtain a cup-shaped green body. In step S14, a hot press is used for hot press molding to obtain a chip inductor blank, and then the chip inductor blank is demolded, baked, and cured to obtain an inductor semi-finished product. In step S15, a constant temperature heating spraying device is used to spray insulating resin protective material on the surface of the inductor semi-finished product.
In a preferred embodiment of the present invention, the soft magnetic alloy powder in steps S11 and S13 is prepared by mixing, granulating and sieving soft magnetic alloy powder, a binder and a lubricant.
In a preferred embodiment of the present invention, the soft magnetic alloy powder includes at least one of amorphous soft magnetic alloy powder, nanocrystalline soft magnetic alloy powder, iron-silicon-aluminum alloy powder, iron-silicon-chromium alloy powder, iron-silicon-nickel alloy powder, iron-silicon-aluminum-nickel alloy powder, iron-nickel-aluminum alloy powder, carbonyl iron powder;
The binder comprises at least one of epoxy resin, polyurethane, silicone resin, organic silicon resin, amino resin, polyimide, phenolic resin, cyanate ester and acrylic resin;
the lubricant comprises at least one of zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, graphite powder and graphene.
In the preferred embodiment of the present invention, the T-shaped green body and the cup-shaped green body are obtained by cold press molding the soft magnetic alloy powder in steps S11 and S13.
Example 1:
in this embodiment, the soft magnetic alloy powder is a composite powder formed by mixing Fe-Si-B-C amorphous soft magnetic alloy powder and carbonyl iron powder, the binder is epoxy resin, the lubricant is graphene, and the composite powder, the binder, the lubricant and acetone are mixed and then screened to obtain the target soft magnetic alloy powder, and in this embodiment, as shown in fig. 3 to 6, the method for preparing the sheet inductor specifically includes the following steps:
s1, prefabricating a T-shaped blank: the screened soft magnetic alloy powder is put into a T-shaped die with a preset structure and size, a high-precision servo forming press is started to perform punch forming at normal temperature, then demoulding is performed to obtain a T-shaped blank body 1 with columnar protrusions 12, and then the T-shaped blank body is put into an oven to be baked to obtain the T-shaped blank body 1 with certain strength;
Wherein the cold pressing pressure adopted when the T-shaped green body 1 is pressed is 3T/cm2The pressure maintaining time is 1 s; and (3) when the T-shaped blank body 1 is formed by baking, placing the T-shaped blank body 1 in baking equipment with a temperature rise and fall step curve at 140 ℃ for baking for 0.5h to obtain the T-shaped blank body 1 with certain strength.
S2, winding: precisely winding 8.5 turns of flat enameled wire 21 with the specification of 0.18mm × 1.0mm on the columnar protrusion 12 of the T-shaped blank 1 prepared in step S1 by using a precise vertical winding machine, specifically, winding the flat surface of the flat enameled wire 21 along a manner perpendicular to the plane of the columnar protrusion 12 of the T-shaped blank 1, bending pins at two ends, and attaching the flat surface of the flat enameled wire 21 to the bottom surface of the flat plate 11 of the T-shaped blank 1 to obtain an assembly of the T-shaped blank 1 and a coil, i.e., a wound T-shaped blank 1 (as shown in fig. 3).
S3, preparing a cup-shaped blank: loading the screened soft magnetic alloy powder into a cup-shaped die with a preset structure and size, starting a high-precision servo forming press to perform punch forming at normal temperature to obtain a cup-shaped blank body 3 (shown in figure 4), placing the cup-shaped blank body 3 into a cold press forming die without separation, and entering the next step along with the die;
wherein the cold pressing pressure used for pressing the cup-shaped blank 3 is 3t/cm 2The dwell time was 1 s.
S4, hot press molding: as shown in fig. 5, the cup-shaped blank 3 prepared in step S3 is placed with a mold with an upward opening in a mold cavity and fixed on a middle mold base 42, the mold is heated and insulated as a whole, then the protrusion of the assembly of the T-shaped blank 1 and the coil prepared in step S2 is implanted downward into the mold cavity of a middle mold 41 with the cup-shaped blank 3, then a hot press forming mold is started to punch downward, the mold is insulated and maintained for a certain time, then the mold is released, a sheet-type inductor blank is prepared, and the sheet-type inductor blank is baked, so as to obtain a cured inductor semi-finished product 5 (as shown in fig. 6);
wherein the hot-pressing pressure adopted during hot-pressing molding is 3t/cm2And keeping the pressure for 150 seconds, keeping the temperature at 180 ℃, and baking and curing the chip inductor blank, wherein the process specifically comprises the step of putting the chip inductor blank into a baking oven for heating and raising the temperature to enable resin in the chip inductor blank to perform a curing reaction to obtain a semi-finished inductor product 5. The resin adopted here is epoxy resin, and only has small volume shrinkage during curing, so that the power inductor blank is not deformed after curing and molding. Specifically, the baking curing temperature is 180 ℃, baking equipment with a temperature rising and decreasing step curve can be selected, heat preservation is carried out for 3 hours, and finally the inductor semi-finished product 5 is obtained, wherein the size of the inductor semi-finished product 5 is 5.3mm multiplied by 5.5mm multiplied by 3.0 mm.
S5, spraying: coating a layer of epoxy resin protective material on the surface of the inductor semi-finished product 5 prepared in the step S4 by adopting constant-temperature heating spraying equipment, and then baking the sprayed inductor semi-finished product 5 to cure the epoxy resin on the surface of the inductor semi-finished product 5;
wherein the baking conditions are as follows: baking the semi-finished product 5 at 150 ℃ for 2h to cure the resin on the surface of the semi-finished product 5 and obtain certain strength.
S6, electrode preparation: as shown in fig. 6, the insulating resin protective material and the copper wire enamel at the copper electrode 51 of the inductor semi-finished product 5 after spraying, which are prepared in step S5, are stripped, the copper electrode 51 of the inductor semi-finished product 5 is coated with a layer of rosin flux, then the electrode protruding from the surface of the substrate of the inductor semi-finished product 5 is completely immersed in a tin material (electrode material) in a solder bath, the electrode material is taken out after being immersed for a certain time, a high-temperature and high-pressure hot air gun is started while the electrode material is taken out, the tin layer on the surface is leveled, finally, a layer of tin is uniformly covered at the flux, and electrode leading-out is realized, so as to obtain the chip inductor.
Wherein the temperature of the soldering tin tank is 270 ℃, the soaking time of the electrode on the surface part of the convex matrix of the inductance semi-finished product in the soldering tin tank is 3s, the temperature of the high-temperature and high-pressure hot air gun is 400 ℃, the pressure is 0.5MPa, the solder tin is loaded in the soldering tin tank, and the thickness of a tin layer covered on the soldering flux is 15 mu m.
An impedance analyzer is utilized to measure that the average inductance Ls of the high-power inductance sample prepared by the preparation method of the embodiment 1 under the condition of 1V/100KHz is 3.19 mu H, the average saturation current Isat is 9.5A, and the average direct current resistance Rdc is 11.5m omega; and testing the terminal strength and weldability of the electrode of the prepared high-power inductance sample, wherein the terminal strength of the motor of the prepared high-power inductance sample is tested by a marble push-pull force testing machine device, and the average terminal strength is 115N.
Comparative example 1:
in the comparative example, the soft magnetic alloy composite powder, the binder, the lubricant and the external insulating coating material which are the same as those in the example 1 are selected, the type and specification of the enameled wire, the number of turns of the wound coil, the electrode structure and size, the size of the finished inductor product and other parameters are the same as those in the example 1, and only the electrode preparation method is different from that in the example 1.
The method specifically comprises the following steps:
s1, prefabricating a T-shaped blank: t-shaped blank 1 was prepared as in example 1S 1.
S2, winding: the winding was as in S2 of example 1.
S3, preparing a cup-shaped blank: the cup-shaped bodies were prepared as in S3 in example 1.
S4, hot press forming: the hot press molding process is as in S4 in example 1.
S5, spraying: the spraying process was as in step S5 of example 1.
S6, electrode preparation: and (5) stripping the insulating resin protective material and the copper wire enamel at the copper electrode 51 of the sprayed inductor semi-finished product 5 prepared in the step (S5), electroplating copper, nickel and tin at the copper electrode 51 of the inductor semi-finished product 5, wherein the thickness of the whole electroplated layer is 15 microns, and leading out the electrode to obtain the chip inductor.
The main properties of the inductor samples prepared by the preparation method of comparative example 1 were measured using the same performance test equipment and conditions as in example 1, and the measured performance parameters are shown in table 1.
Comparative example 2:
in the comparative example, the same soft magnetic alloy composite powder, the same adhesive, the same lubricant and the same external insulation coating material as those in the example 1 were selected, the number of winding turns of the coil, the electrode structure and the size, the size of the inductor finished product and other parameters were the same as those in the example 1, but the circular enameled wire 22 was selected, and the electrode preparation was performed by the conventional process, i.e., copper-nickel-tin electroplating. The preparation method comprises the following steps:
s1, prefabricating a T-shaped blank: the T-shaped blank 1 was prepared as in example 1S 1.
S2, winding: precisely winding 8.5 turns of the T-shaped blank 1 on the columnar bulge by using a precise winding machine in the step S1 
And bending the round enameled wire 22 with the diameter of 0.4mm, and attaching the bent pins at two ends to the flat bottom surface of the T-shaped blank 1 to obtain the assembly of the T-shaped blank 1 and the coil.
S3, preparing a cup-shaped blank: the cup-shaped bodies were prepared as in S3 of example 1.
S4, hot press forming: as shown in FIG. 7, the hot pressing pressure used in the hot pressing was 3t/cm2The pressure maintaining time is 150s, and the heat preservation temperature is 180 ℃. The process of baking and curing the chip inductor blank specifically comprises the steps of putting the chip inductor blank into an oven for heating and raising the temperature, so that resin in the chip inductor blank is subjected to a curing reaction to obtain electricityAnd (5) feeling a semi-finished product. The resin adopted here is epoxy resin, and only has small volume shrinkage during curing, so that the inductance blank body is not deformed after curing and molding. Specifically, the baking curing temperature is 180 ℃, baking equipment with a temperature rise and fall stepped curve can be selected, heat preservation is carried out for 3 hours, and finally a semi-finished inductor product is obtained, wherein the size of the semi-finished inductor product is 5.3mm multiplied by 5.5mm multiplied by 3.0 mm.
S4, spraying: coating a layer of epoxy resin protective material on the surface of the inductor semi-finished product prepared in the step S4 by adopting constant-temperature heating spraying equipment, and then baking the sprayed inductor semi-finished product to cure the epoxy resin on the surface of the inductor semi-finished product;
Wherein the baking conditions are as follows: baking the semi-finished product 5 at 150 ℃ for 2h to cure the resin on the surface of the semi-finished product 5 and obtain certain strength.
S5, electrode preparation: and (4) stripping the insulating resin protective material and the copper wire enamel at the copper electrode of the sprayed inductor semi-finished product prepared in the step (S5), and electroplating copper, nickel and tin at the copper electrode of the inductor semi-finished product to ensure that the thickness of the whole electroplated layer is 15 mu m, so as to realize electrode lead-out and obtain the chip inductor.
The main properties of the inductor samples prepared by the preparation method of comparative example 2 were measured using the same performance test equipment and conditions as in example 1, and the measured performance parameters are shown in table 1.
Table 1 performance parameters of power inductors obtained in example 1 and comparative examples 1 to 2
Example 2:
in this embodiment, the size specification of the chip inductor is the same as that of embodiment 1, the soft magnetic alloy powder is a composite powder formed by mixing Fe-Si-B-Nb-Cu nanocrystalline soft magnetic alloy powder and carbonyl iron powder, the number of turns of the wound coil is 7.5 turns, and the rest of the inductor structural parameters, raw materials, preparation techniques and process parameters are the same as those of embodiment 1, which is described in detail in embodiment 1. After obtaining a chip inductance sample, an impedance analyzer is utilized to measure that the average inductance Ls of the sample under the condition of 1V/100KHz is 3.28 muH, the average saturation current Isat is 8.8A, and the average direct current resistance Rdc is 10.5m omega; the prepared electrode was subjected to terminal strength and solderability tests, and the average terminal strength was measured to be 117N.
Comparative example 3:
in the comparative example, the soft magnetic alloy composite powder, the binder, the lubricant and the external insulating coating material which are the same as those in the example 2 are selected, the type and the specification of the enameled wire, the number of winding turns of the coil, the structure and the size of the electrode, the size of the finished inductor and other parameters are the same as those in the example 2, and the step of preparing the electrode is different from the step of preparing the electrode in the example 2. The specific electrode preparation step is as S6 in example 1, and finally, a chip inductor is obtained.
The main properties of the inductor samples prepared by the preparation method of comparative example 1 were measured using the same performance test equipment and conditions as in example 2, and the measured performance parameters are shown in table 2.
Comparative example 4
In this comparative example, the same soft magnetic alloy composite powder, the same binder, the same lubricant, and the same external insulating coating material as those used in example 2 were used, and the number of turns of the coil, the electrode structure and the size, and the size of the inductor product were the same as those used in example 2, but the soft magnetic alloy composite powder, the same binder, the same lubricant, and the same external insulating coating material were used, but the number of turns of the coil, the size of the electrode structure, and the size of the inductor product were selected
0.4mm round enameled wire 22, and the conventional process is adopted for preparing the electrode, namely electroplating copper, nickel and tin. The specific method for manufacturing the chip inductor is the same as that of comparative example 2.
The main properties of the inductor samples prepared by the preparation method of comparative example 4 were tested using the same performance test equipment and conditions as in example 2, and the measured performance parameters are shown in table 2.
Table 2 performance parameters of power inductors obtained in example 2 and comparative examples 3 to 4
In summary, table 1-table 2 includes the differences in the manufacturing process of the power inductor between examples 1-2 and comparative examples 1-4, as well as the dc resistance Rdc (m Ω), saturation current isat (a), inductance Ls (μ H) and terminal strength (N) of the electrode of the resulting high power inductor.
By comparing the manufacturing processes and performance parameters of the embodiment 1 and the comparative examples 1-2, and the embodiment 2 and the comparative examples 3-4, it can be seen that the inductance prepared by the flat enameled wire can greatly reduce the direct current resistance of the inductance product on the premise of not influencing the inductance Ls and the saturation current Isat, so that the power loss of the inductance product during working can be effectively reduced.
By comparing the manufacturing processes of the embodiment 1 and the comparative embodiment 2, and the manufacturing processes of the embodiment 2 and the comparative embodiment 4 and the electrode performance parameters, it can be seen that a more uniform tin layer can be obtained by the tin immersion process, the welding strength of the inductance product is effectively improved, and adverse conditions such as short circuit and insufficient soldering are avoided.
In addition, compared with a round enameled wire, the flat enameled wire has a better sectional area, the round enameled wire can be subjected to subsequent processes only by filling the copper electrode to a proper area, and the flat enameled wire can be directly used for manufacturing the electrode on the copper electrode through a tin immersion process, so that the whole process is simple and convenient, the production cost can be effectively reduced, and the production efficiency is greatly improved; meanwhile, the deformation space of the coil can be effectively limited by combining the prefabricated T-shaped blank body and the cup-shaped blank body, and the coil is prevented from being exposed, deformed and even broken in the hot pressing process, so that the shielding performance and the inductance value of the inductor are ensured, and the comprehensive performance of the product is improved.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
Claims (8)
1. A method for preparing a chip inductor is characterized by comprising the following steps:
step S1, preparing a semi-finished product: preparing a soft magnetic alloy powder material and an enameled wire into an inductance semi-finished product by prefabricating a soft magnetic alloy blank, winding, hot-pressing and baking, and spraying an insulating resin protective material on the surface of the inductance semi-finished product;
step S2, preparing an inner electrode: stripping the insulating resin protective material and the copper wire paint skin at the copper electrode of the semi-finished inductor prepared in the step S1;
step S3, surface pretreatment: coating a layer of soldering flux on the copper electrode;
step S4, outer electrode preparation: and completely immersing the electrode on the surface part of the convex substrate of the semi-finished inductor into a liquid electrode material in a solder tank, taking out the electrode after soaking for a certain time, starting a high-temperature and high-pressure air gun while taking out the electrode, leveling the electrode material on the surface of the semi-finished inductor, uniformly covering a layer of the electrode material on the soldering flux, leading out the electrode and obtaining a chip inductor finished product.
2. The method for manufacturing chip inductor according to claim 1, wherein the step S1 comprises:
step S11, prefabricating a T-shaped blank: soft magnetic alloy powder is put into a T-shaped die and is pressed and formed, and then demoulding and baking are carried out to obtain a T-shaped green body;
step S12, winding: winding a flat enameled wire at the columnar bulge of the T-shaped blank prepared in the step S11 in a vertical winding mode, bending pins at two ends, and attaching the flat surface of the flat enameled wire to the flat bottom surface of the T-shaped blank to obtain a wound T-shaped blank;
step S13, prefabricating a cup-shaped blank: soft magnetic alloy powder is filled into a cup-shaped mold and is pressed and molded to obtain a cup-shaped blank body, the cup-shaped blank body is not demolded and enters the cup-shaped mold along with the cup-shaped mold
Step S14;
step S14, hot press molding: placing the cup-shaped blank prepared in the step S13 with an upward opening along with the cup-shaped mold, implanting the cylindrical protrusion of the T-shaped blank of the winding prepared in the step S12 into the opening of the cup-shaped blank in a downward manner, performing hot press molding, and then demolding, baking and curing to obtain the semi-finished inductor.
3. The method of claim 2, wherein the soft magnetic alloy powder in steps S11 and S13 is prepared by mixing, granulating, drying and sieving soft magnetic alloy powder, binder and lubricant.
4. The method for manufacturing a chip inductor according to claim 3, wherein the soft magnetic alloy powder comprises at least one of amorphous soft magnetic alloy powder, nanocrystalline soft magnetic alloy powder, iron-silicon-aluminum alloy powder, iron-silicon-chromium alloy powder, iron-silicon-nickel alloy powder, iron-silicon-aluminum-nickel alloy powder, iron-nickel-aluminum alloy powder, and carbonyl iron powder;
the binder comprises at least one of epoxy resin, polyurethane, silicone resin, organic silicon resin, amino resin, polyimide, phenolic resin, cyanate ester and acrylic resin;
the lubricant comprises at least one of zinc stearate, magnesium stearate, aluminum stearate, calcium stearate, graphite powder and graphene.
5. The method for manufacturing a chip inductor according to claim 1, wherein the electrode material in step S4 is one of gold, silver, nickel, tin, copper-tin alloy, nickel-chromium alloy, and tin-lead alloy.
6. The method for manufacturing a chip inductor according to claim 1, wherein in step S4, the temperature in the solder bath is 240 ℃ to 300 ℃, the temperature of the high-temperature high-pressure air gun is 300 ℃ to 500 ℃, and the pressure is 0.5MPa to 0.8 MPa.
7. The method of claim 1, wherein the insulating resin protective material comprises at least one of mica, epoxy resin, silicone resin, phenolic resin, glass reinforced polyester, silicone resin, polyester resin, and silicone resin.
8. The method for manufacturing a chip inductor according to claim 2, wherein in the steps S11 and S13, the T-shaped blank and the cup-shaped blank are obtained by cold press molding the soft magnetic alloy powder.
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