JPH11261182A - Circuit board and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the need for Cu foil etching, expand the selectable width of a substrate constituting a circuit board and facilitate forming a flexible circuit board, by providing a conductive resin wiring pattern contg. solder power and Cu powder on at least one surface of an insulator base. SOLUTION: This circuit board 100 has wiring patterns 2, 2 on both surfaces of a paper-phenol base 1, the wiring patterns are conducted electrically through through-holes 3, and components inserting holes 4 are also provided. The wiring pattern 2 is made by screen printing a conductive resin mode of a solder power, Cu powder, epoxy resin or acrylic resin, etc., and heating to harden the conductive resin. Or both main flat planes of the base 1 and through-hole 3 inner surfaces are insulated, a conductive resin contg. a solder power and Cu powder is injected by the injection forming, and the wired base 1 is held for several minimum to harden the injected conductive resin in a heated die after setting the wiring pattern 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board provided with a wiring pattern for an electric circuit made of a conductive resin and a method of manufacturing the same.

[0002]

2. Description of the Related Art An electric circuit board provided with a wiring pattern (hereinafter referred to as a circuit board). For example, a printed wiring board or the like is formed by etching an insulating board provided with copper foil on one or both sides. General. Hybrid IC (HI) in which AG-Pd or a conductive resin containing a conductive filler such as silver, copper or carbon is printed as a wiring pattern on a ceramic sheet base material such as alumina.
A circuit board for C) is also used.

As the conductive resin forming the HIC wiring pattern, for example, 70 to 150 parts of carbon powder such as acetylene black and 100 parts of a mixture of 5 to 50 parts of a bisphenol type epoxy resin, 0.
7 to 3 μm, maximum diameter of 25 μm or less, and Mohs hardness of 4
A composition containing 8 to 30 parts of the above organic or inorganic powder, for example, silica, or 60 to 85% by weight of silver powder, 3 to 20% by weight of an epoxy compound having a naphthalene skeleton, and two of them within one molecule. A composition containing 0.1 to 20% by weight of a compound having a phenolic hydroxyl group is proposed.

[0004]

However, the above-mentioned conventional printed wiring board requires a wet process of etching copper foil, and also requires a drainage treatment facility for preventing pollution. Also,
The wiring pattern creation period is long. Further, since the resin member is used as a base (base material), recycling treatment after disposal is not easy, leading to global environmental pollution. The circuit board for HIC requires high-temperature baking of the base material, and the substrate is not flexible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a circuit board which eliminates the need for etching of a copper foil, expands the selection range of the base material constituting the circuit board, and can be easily manufactured in a short period of time. It is another object of the present invention to facilitate the production of a flexible circuit board, improve the recycling rate, and protect the global environment.

[0006]

In order to solve the above-mentioned problems, a circuit board of the present invention is provided with an insulating material (an insulating resin is applied or an alumite process is applied to a main surface and an inner surface of a through hole). A wiring pattern made of a conductive resin containing a solder powder and a copper powder was provided on at least one side of the base material subjected to the above.

The resistance value of the conductive resin is about 10 times that of copper. (The specific resistance of copper is 1.71 μΩ.c at 20 ° C.
m). In addition, the solder powder constituting the conductive resin in the present invention has a configuration in which Sn is a main component and a small amount of Ni and Cu is used as an additive. (All are 5% or less.) The solder powder is not limited to the above-described configuration. For example, Japanese Unexamined Patent Publication (Kokai) No. 9-94688 discloses an alloy comprising 7 to 10% by weight of Zn, 0.01 to 1% by weight of Ni, and the remaining Sn, which contains 0.1 to 3.5% by weight of Ag and 0.1 to 3% of Cu.
There has been proposed a configuration in which, for example, 0.5% to 6% by weight of Bi, 0.5% to 3% by weight of In, and 0.001% to 1% of P are added. Ag-Sn based lead-free solders have also been proposed. Furthermore, Sn-Zn-Bi-Cu, Sn-
Zn-Bi-Ag based 4-5 element lead-free solder etc. (for example, JP-A-9-271981, JP-A-9-85)
484, JP-A-9-94688).

The binder resin constituting the conductive resin includes epoxy, PMMA, PET, PS, PI, A
Any one selected from resins such as BS, phenol, and vinyl chloride.

As the insulating base material, a resin sheet (epoxy resin, phenol resin, acrylic resin, etc.), a resin film sheet, a rubber sheet, a woven or nonwoven fabric made of cotton, hemp, plastic fibers, etc., paper, paper phenol, main surface Anodized aluminum sheet and the inner surface of through hole, metal substrate (for example, iron substrate) coated with insulating resin, etc., commercially available color coated steel sheet, elastically deformable ceramic sheet, biodegradable plastic sheet, etc. One of them.

As the biodegradable plastic, a denatured protein such as gluten, a member obtained by kneading denatured protein with paper,
Natural polymer Novamont (trade name: Matterby / Nippon Synthetic Chemical Industry), microbial polyester ICI (trade name: Biopol / ICI Japan), chemically synthesized aliphatic polyester (trade name: Bionole / Showa Kobunshi) )). The photobiodegradable plastic had a configuration in which 6-nylon, polycaprolactone, and polyethylene glycol were mixed. Substrate thickness is 0.1mm ~ 2mm
Degree. Of these, resin sheets, resin film sheets, plastic fibers, etc. are made of recycled PET, P
Any one selected from P, PS, PI, PMMA and the like may be used.

Means for arranging a wiring pattern made of a conductive resin on the insulating base material include general screen printing, dispenser drawing using air pressure and a discharge nozzle, and injection molding (so-called outsert molding method). Either means was used. Of course, any means such as ink jet may be used. Further, through holes (through holes) were formed in the substrate by laser processing or punching (press punching), and the wiring patterns provided on both surfaces of the substrate were electrically connected. Further, if necessary, the coefficient of thermal expansion of the base material and the coefficient of thermal expansion of the wiring pattern (conductive resin) are approximated, and even if the environmental temperature changes in the range of −40 ° C. to + 80 ° C., the wiring pattern Does not peel off from the base material nor break.

With the above structure, the etching process of the copper foil becomes unnecessary. In addition, a circuit board can be created in a short time. Woven fabrics made of cotton cloth, linen cloth, canvas cloth, ceramic sheets, anodized aluminum sheets, insulated metal substrates, color coated steel sheets, etc. are easy to recycle and are effective in protecting the global environment. Further, by making the thermal expansion coefficients of the base material and the conductive resin substantially the same, the disconnection rate of the wiring pattern is reduced with respect to a change in environmental temperature.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first aspect of the present invention is characterized in that a wiring pattern for an electric circuit made of a conductive resin containing solder powder and copper powder is provided on at least one surface of a substrate. A circuit board, which eliminates the need for etching copper foil. In addition, a circuit board can be created in a short time.

Further, in the second invention, the solder powder is made of Sn
The circuit board according to the first aspect, wherein the resistance of the wiring pattern is reduced to about 10 times the resistance of copper. Can be

Further, a third invention provides a process for forming a through hole for a through hole in a base material, and a method for forming an electric circuit comprising a conductive resin containing solder powder and copper powder on at least one surface of the base material. A method of manufacturing a circuit board, comprising a step of arranging a wiring pattern, and obviating the need for etching a copper foil. In addition, a circuit board can be created in a short time.

Further, a fourth invention provides a step of forming a through-hole for a through-hole in a metal substrate, a step of forming an insulating resin film on a surface of the metal substrate and an inner surface of the through-hole, Disposing a wiring pattern for an electric circuit made of a conductive resin containing a solder powder and a copper powder on at least one side of the material. It is large, easy to recycle, and helps protect the environment.

Further, the fifth invention comprises a step of forming a through hole for the through hole in the AL base material, an alumite treatment step of forming an insulating film on the main surface and the inner surface of the through hole, Arranging a wiring pattern for an electric circuit made of a conductive resin containing solder powder and copper powder on at least one surface. It is large, easy to recycle, and helps protect the environment.

Further, the sixth invention is characterized in that a step of forming a through hole for a through hole in a color coated steel sheet, a step of forming an insulating film on the inner surface of the through hole, and a step of forming a solder powder on at least one side of the color steel sheet. And a step of arranging a wiring pattern for an electric circuit made of a conductive resin containing copper powder. ,
It is easy to recycle and contributes to environmental protection.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A circuit board according to an embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a plan view of a main part of a concept of a circuit board according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the main part taken along the line S--S of FIG. 1, and FIG. FIG. 4 is a sectional view of a main part of a circuit board according to another embodiment of the present invention, and FIG. 4 is a flowchart of a method of manufacturing a circuit board according to one embodiment of the present invention.

The circuit board 100 shown in FIG.
Wiring patterns 2 are provided on both sides of a paper phenolic substrate 1 having a thickness of m, and wiring patterns 2 and 2 provided on both sides are electrically connected through through holes (holes) 3.
Further, a component insertion hole 4 is provided. The wiring pattern 2 is composed of 10 to 60% by weight of solder powder and 10 to 20% of copper powder.
A conductive resin consisting of a weight percent of an epoxy resin or an acrylic resin consisting of the remainder was screen-printed. After printing, 15
The conductive resin was cured by heating at 0 ° C. for about 2 hours.

The solder powder contains Sn as a main component, Ni and Cu as additives in a range of 5% by weight or less, respectively, and the resistance value of the wiring pattern is set to about 10 times the resistance value of the copper foil. The solder powder is eutectic solder (Sn61.9%, P
Needless to say, any alloy may be used, for example, b38.1%).

The means for applying a conductive resin to the inner surface of the through-hole was carried out simultaneously with the step of printing the wiring pattern 2. That is, the conductive resin can be applied to the inner surface of the through-hole 3 by vacuum-suctioning the conductive resin through the through-hole 3 during the printing process of the wiring pattern.

Needless to say, the binder resin of the conductive resin may be a phenol resin so that the coefficient of linear expansion of the binder resin is similar to that of the paper phenol of the base material 1. As a matter of course, the through hole 3 is formed by punching (press punching), laser processing, drilling, or the like as a pre-process for printing and forming a wiring pattern. The through hole 3 has a function of conducting the wiring patterns 2 provided on both sides and also serves as a locking function for preventing the wiring patterns 2 from peeling off from the substrate 1.

Further, it is the same that the base material 1 may be made of any member and thickness. For example, instead of a rigid resin sheet, a resin film sheet having a thickness of about 0.1 to 0.2 mm, a woven fabric, a nonwoven fabric, an elastic ceramic sheet, or the like may be used. Resin film sheet,
A circuit board made of a woven fabric, a non-woven fabric or the like is flexible and can be folded. The circuit board 200 shown in FIG.
A sheet-like substrate is formed by impregnating or applying a biodegradable plastic or the like on a woven fabric 31 (or non-woven fabric) made of fibers such as cotton, hemp, canvas, PET, PMMA, and the like. The wiring pattern 32 is printed with a conductive resin containing solder powder and copper powder, and the wiring patterns 32, 32 provided on both sides are made conductive using through holes. Further, a component insertion hole 34 is provided.

With the above configuration, the circuit board of the present invention eliminates the need for etching the copper foil. In addition, a circuit board can be created in a short time.

(Embodiment 2) FIG. 4 shows a process of manufacturing a circuit board in this case. The substrate constituting the circuit board was a metal substrate such as an iron plate, a color coated steel plate, an AL (aluminum) plate, or the like. In the first step, the substrate has a diameter of 0.3 to 1 mm.
A laser hole is formed in a through hole of about mm. In the second step, both main planes of the base material and the inner surface of the through hole are insulated. That is, in the case of an iron plate or the like, an epoxy resin,
Apply acrylic resin etc. to a thickness of several tens of μm,
It is cured by heating at 0 to 150 ° C. for about 1 to 2 hours. A
In the case of the L sheet, an insulating oxide film (Al ↓ 2O ↓ 3 film) is formed on both surfaces and the inner surface of the through hole to a thickness of several μm to several tens μm by alumite treatment after perforating the through hole. In particular, by applying a color alumite treatment of seven colors such as black, red, green, and blue, the heat radiation effect is improved by several tens of percent. In the case of a color-coated steel sheet, a resin may be applied only to the inner surface of the through-hole and subjected to insulation treatment. In the third step, a wiring pattern is provided by injecting a conductive resin containing the solder powder and the copper powder by injection molding (outsert molding). In the fourth step, the substrate subjected to the wiring process is held in the heated mold for several minutes, and the injected conductive resin is cured.

The circuit board according to the second embodiment has a large heat radiation effect, is easy to recycle, and is useful for environmental protection. When the substrate is an aluminum sheet, it is lightweight.

In the first and second embodiments, the conductive resin forming the wiring pattern is not limited to the structure including the solder powder and the copper powder, but may be any general conductive resin. In addition to the above, any means such as an ink jet method, a dispenser drawing method using air pressure and a nozzle may be used as a means for applying the conductive resin in a wiring pattern.

Further, the type of the substrate may be an arbitrary member. For example, a sheet made of the biodegradable plastic, a color-coated steel sheet (thickness 0.5 to 2 mm) having a main plane coated with a resin of several μm to several tens μm in advance may be used. When the color coated steel sheet is used, a circuit board provided with a wiring pattern on only one side can very easily constitute a circuit board. Further, even when a wiring pattern is formed on both surfaces, it is sufficient to apply an insulating resin only on the inner surface of the through hole, so that the manufacturing process and schedule are shortened, and responsiveness is improved.

In addition, resins (general resins such as biodegradable plastics, epoxy resins, acrylic resins, phenolic resins, PET resins), PVA, and starch-based materials are sliced on wooden boards or plywood (such as veneer boards) sliced to a thickness of 1 to 2 mm. It may be formed into a sheet by applying or impregnating a paste or an adhesive. In particular, substrates coated with starch-based paste or biodegradable plastic or impregnated with about 10 to 30% by weight are easy to dispose and recycle after use, and are effective in protecting the global environment. Similarly, about 10 to 30% by weight of the resin and the sizing agent are mixed with wood flour (sawdust), glass powder, garbage ashes, etc., and the mixture is pressed and formed into a sheet, or hemp is superimposed on cellulose of the thinned wood. The resin and the paste are impregnated with about 10 to 30% by weight and pressure-formed into a sheet, or the resin or the paste is applied to a thick paper (about 0.5 to 2 mm), cardboard, or the like. The sheet may be impregnated with about 50% by weight. Further, the resin or the paste is applied to a woven or non-woven fabric made of cotton, linen, canvas, PET resin, PI resin, glass fiber, or the like, or
The sheet may be impregnated and cured at about 0 to 50% by weight.

It is needless to say that the shape of the various substrates is not limited to a sheet shape, but may be any shape such as a three-dimensional shape. When the substrate has a three-dimensional shape, it is preferable to form a wiring pattern by an injection molding method.

[0033]

As described above, according to the circuit board and the method of manufacturing the same of the present invention, the copper foil is not required to be etched. In addition, a circuit board can be created in a short time. A circuit board made of a resin film sheet, a woven fabric, a nonwoven fabric, or the like is flexible and can be folded. A circuit board using a metal substrate has a large heat radiation effect and is easy to recycle. Circuit boards using wood board, wood flour, paper, cellulose, cotton, linen, canvas, etc. are also easy to recycle and are useful for environmental protection. As a result, the recycling rate is improved, which contributes to environmental conservation and effective use of resources.

[Brief description of the drawings]

FIG. 1 is a plan view of the concept of a circuit board according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of FIG. 1 taken along section lines S to S;

FIG. 3 is a sectional view of a main part of a circuit board according to another embodiment of the present invention.

FIG. 4 is a flowchart of a circuit board manufacturing process according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material (resin, aluminum sheet, woven cloth, etc.) 2, 32 Wiring pattern 3, 33 Hole (through hole) 4, 34 Component insertion hole 31 Woven (or nonwoven) 100, 200 Circuit board

Claims (22)

[Claims] 1. A circuit board comprising an electric circuit wiring pattern made of a conductive resin containing solder powder and copper powder on at least one surface of a substrate. 2. The circuit board according to claim 1, wherein the solder powder has Sn as a main component and Ni and Cu as additives. 3. The circuit board according to claim 1, wherein the solder powder is eutectic solder. 4. The circuit board according to claim 1, wherein electric circuit wiring patterns disposed on both sides of the base material are conducted through through holes formed in the base material. 5. A base material is a resin sheet, a resin film sheet, a woven fabric, a nonwoven fabric, a paper sheet, a paper phenol, a biodegradable plastic sheet, a metal substrate whose surface is insulated, Al
The circuit board according to any one of claims 1 to 4, wherein the circuit board is any one selected from an AL sheet and a ceramic sheet having a ↓ 2O ↓ 3 film. 6. A member obtained by kneading a biodegradable plastic sheet with denatured protein, paper and denatured protein, natural polymer Novamont, microbial polyester ICI, chemically synthesized aliphatic polyester, 6-nylon, polycaprolactone and polyethylene. 6. The circuit board according to claim 5, wherein any one selected from a mixture of three glycols is used. 7. A step of forming a through hole for a through hole in a base material, and arranging a wiring pattern for an electric circuit made of a conductive resin containing solder powder and copper powder on at least one surface of the base material. And a method of manufacturing a circuit board. 8. The method for manufacturing a circuit board according to claim 7, wherein the through hole is formed by one of punching and laser processing. 9. The method for manufacturing a circuit board according to claim 8, wherein the wiring pattern is disposed by using any one of dispenser drawing and injection molding. 10. The method according to claim 9, wherein the solder powder contains Sn as a main component and Ni and Cu as additives. 11. A step of forming a through hole for a through hole in a metal base, a step of forming an insulating film on at least one of a surface of the metal base and an inner surface of the through hole, Disposing a wiring pattern for an electric circuit made of a conductive resin containing solder powder and copper powder on one side. 12. A step of forming a through hole for a through hole in an AL substrate, a step of forming an oxide film on a surface of the AL substrate and an inner surface of the through hole, and forming a conductive film on at least one surface of the AL substrate. Arranging a wiring pattern for an electric circuit made of one of a resin or a conductive resin containing a solder powder and a copper powder. 13. The method according to claim 12, wherein the color of the oxide film is any one of seven colors. 14. The method according to claim 12, wherein the through-hole is formed by one of a punching process and a laser process. 15. The method according to claim 14, wherein the wiring pattern is provided by injection molding. 16. A step of forming a through hole for a through-hole in a color steel plate, a step of forming an insulating film on the inner surface of the through-hole, and a conductive resin, or a solder powder and a copper powder on at least one surface of the color steel plate. Disposing a wiring pattern for an electric circuit made of any one of the conductive resins including the following. 17. The method for manufacturing a circuit board according to claim 16, wherein the through-hole is formed by one of punching and laser processing. 18. The method according to claim 17, wherein the wiring pattern is provided by injection molding. 19. An AL substrate having an oxide film formed on a main surface and an inner surface of a through hole, on at least one surface of the AL substrate, a conductive resin or a conductive resin containing a solder powder and a copper powder. A circuit board on which a wiring pattern for an electric circuit is provided. 20. An electric circuit comprising a conductive resin or a conductive resin containing a solder powder and a copper powder on at least one side of a color steel plate having an insulating film formed on an inner surface of a through hole. A method for manufacturing a circuit board, wherein a wiring pattern is provided. 21. A sheet-like base material prepared by applying or impregnating one of a biodegradable plastic and a starch-based paste onto one of a sliced wooden board and a plywood, A circuit board, wherein at least one side of the circuit board is provided with a wiring pattern for an electric circuit made of any one of a conductive resin or a conductive resin containing solder powder and copper powder. 22. A base material formed into a sheet by applying or impregnating one of a biodegradable plastic and a starch-based paste onto one of a thick paper and a cardboard, A circuit board, comprising: a wiring pattern for an electric circuit formed of at least one of a conductive resin and a conductive resin containing a solder powder and a copper powder on at least one surface of the substrate.