JPS63193594A - Manufacture of wiring board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a wiring board in which a conductive circuit portion is directly patterned on the surface of a molded body.

[Prior Art] Conventional printed wiring boards (PCBs) are made by integrating copper foil on both or one side of a flat plastic plate made of glass epoxy or paper phenol using a thermocompression molding method, and applying etching resist to the conductive parts (pattern parts). Apply and cure using screen printing or photo printing. After that, etching is performed using iron chloride or the like to remove the copper foil other than the conductive parts, and then the resist is dissolved and removed and patterning is performed to manufacture a PCB.

Another method is to use a flat plastic plate with an adhesive layer on both sides or one side, roughen the surface, apply a catalyst for thermoelectrolytic plating to activate the surface, and apply resist to non-conductive areas (non-patterned areas). is applied by screen printing or photo printing. After curing the resist, a copper plating layer is formed on the conductive area (pattern area) without resist in a hot electrolytic plating bath, and then PC is applied.
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[Problems to be Solved by the Invention] Since the conventional method has the above-mentioned configuration, the plastic substrate needs to be a flat plate.

For example, it is extremely difficult to integrate copper foil into a molded product having a complex three-dimensional shape, and it is also difficult to screen print a resist.

In addition, a method of forming a photocurable resist using a photographic method is found in, for example, Japanese Patent Laid-Open No. 81-113295, but it requires the use of a photocuring mask with a complicated three-dimensional shape, and the mask and Depending on the accuracy of the degree of adhesion of the molded product, light may leak in or be misaligned, and when focusing on a deep part of the shape, overexposure of other parts may occur. In addition, in order to improve the adhesion between the molded product and resist, conductive ink, etc., it is necessary to remove residual stress from the molded product and roughen the surface by oxidation, etching, etc.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and is a method for manufacturing a wiring board in which a conductive circuit portion is formed on the surface of a molded body serving as a board. After producing a molded body having a layer of plating precursor material on the surface having plating nuclei for electroless plating in a mold, and then masking the part of the surface of the plating precursor material layer that does not become a conductive circuit part with a masking material. , provides a method for manufacturing a wiring board, characterized in that a conductive circuit portion is formed on the surface of a molded body by electroless plating.

In the present invention, the molded body before electroless plating is a flat plate or a three-dimensional molded body of various complicated shapes, which can be obtained by closed molding. Various molding methods using synthetic resins or fiber-reinforced synthetic resins can be used for closed molding, but in particular injection molding, transfer molding, injection transfer molding, injection compression molding, pressure W
m-molding etc. are preferred.

The molds used for these moldings are vertical, horizontal,
Alternatively, various molds such as a split mold divided into three or more parts can be used. .

In the present invention, as a method for manufacturing a molded body having a layer of a plating precursor material having plating nuclei for electroless plating in a mold, a molded body 1 is molded as shown in FIG. Before solidifying or after solidifying, the second
As shown in the figure, the mold 2 is moved by about 0.01 to 1.0 cm to form a cavity between the mold and the molded body, and the plating precursor material 3 having plating nuclei is injected into this cavity. A preferred method is to slightly close the moved mold to form a molded body having a layer of plating precursor material on its surface. In addition to this, a suitable method is to form a layer of plating precursor material in advance on the inner surface of the mold by spraying or brushing, and then integrate this layer and the molded object in the mold. After the plating precursor material is solidified,
After taking it out of the mold, masking the part of the surface of the plating precursor material layer that will not become a conductive circuit part with a mask material 4 as shown in FIG. A wiring board having a conductive circuit portion 5 formed thereon as shown in FIG. 4 can be obtained.

As the mask material, masking tape or a convex resin or metal jig with an elastic body such as rubber or soft urethane resin at the tip may be used.

In the present invention, as a plating precursor material having a plating core for electroless plating, at least one metal powder such as silver, copper, or palladium is combined with an epoxide resin, a thermosetting resin such as an unsaturated polyester resin, or a polyphenylene sulfide resin. , conductive ink or pellets obtained by dispersing in thermoplastic resin such as polyetherimide resin, polysulfone resin, polyallylsulfone resin, or silver chloride-palladium solution, palladium chloride-tin solution, copper chloride-copper Examples include electroless plating catalyst solutions such as solutions. The content of metal powder in the conductive ink or pellets is desirably 30 to 80% by weight, preferably 40 to 60% by weight in view of uniform dispersibility and conductivity. Furthermore, by containing 20 to 60% by weight of glass fibers or carbon fibers in the conductive ink or pellets, the bonding strength with the molded body can be increased. In the case of conductive ink or pellets, the adhesion of electroless plating can be further improved by roughening the surface by sandblasting, hydrophilic treatment, or the like. This plating precursor material preferably has a surface resistance of about 10 to 50 KΩ/l+a2 so as not to be electrically conductive. The thickness of the plating precursor material layer is
l, 0 to 100μ, preferably 2.0 to 20μ.

As the molding material used for molding, the following various synthetic resins can be used. That is, thermoplastic polyester resins represented by polybutylene terephthalate resins and polyethylene terephthalate resins, copolymers and mixtures of polyester resins and other resins, polymer alloys, modified polyester resins, polyphenylene sulfide resins, polyamide resins, and polyimides. Resin, polyetherimide resin, polypropylene resin, AS resin, A
BS resin, polycarbonate resin, polyallylsulfone resin, polysulfone resin, polyacetal resin, polyallylsulfone resin, polyethylene resin, polyvinyl chloride resin, polyether ether ketone resin, fluororesin, polyphenylene oxide resin, (meth)acrylic resin, Various thermoplastic resins such as thermoplastic polyurethane resins, phenolic resins, unsaturated polyester resins, furan resins, alkyd resins, allyl resins, melamine resins, silicone resins, thermosetting polyurethane resins, vinyl ester resins, urea resins, etc. It is a curable resin.

These resins are preferably fiber-reinforced synthetic resins mixed with the following reinforcing fibers, since this increases the strength and heat resistance of the wiring board. That is, glass lam, carbon fiber, poron fiber, fused silica fiber, silica fiber, alumina R
Male, zirconia HAm, boron nitride m fiber, silicon nitride m
Inorganic fibers such as fiber, boron carbide fiber, silicon carbide fiber, asbestos fiber, metal tarra, or hemp, vinylon,
Natural or synthetic fibers such as polyamide and polyester.

A preferred molding material is MC1, which is suitable for molding such as injection and/or transfer molding, and is a resin paste made by mixing an unsaturated polyester resin with a filler, a catalyst, a mold release agent, a chemical thickener, etc., and glass chopped strands. In addition, kneaded products can also be mentioned.

In addition, SMC1 suitable for molding such as compression molding, that is, a sheet in which matte chopped glass fibers are impregnated with the resin paste, can be mentioned.

By performing electroless plating on a portion that has been subjected to so-called sensitization treatment or activation treatment using the plating core of electroless plating, it is possible to form a highly adhesive conductive circuit portion. Since a copper coating is usually used for conductive circuit parts, the electroless plating bath should be a water-soluble copper salt of an inorganic or organic acid, such as copper chloride, copper sulfate, copper acetate, copper bromide, or copper iodide. A copper plating bath is preferred. In order to perform electroless plating efficiently, this copper plating bath usually contains caustic alkali and 1.
It is possible to add an alkaline copper salt aqueous solution containing EDTA, sodium citrate, or sodium gluconate, or a reducing liquid containing a reducing agent such as formalin, sodium hypophosphite, hydrazine, hydrazine sulfate, or glyoxal. preferable. On the copper coating of the conductive circuit part,
For the purpose of rust prevention, nickel mesh leather can also be applied by electroless plating similar to the above.

[Example] A molded body 1 as shown in FIG. 1 was transfer molded using BMC resin. The mold temperature was 140°C, the curing time was 1.5 minutes, and the average wall thickness was 3 mm. Thereafter, the mold was raised by 5 mm, and a solution containing 20% tin-palladium was injected and coated, and heat-cured by repressurizing for 1 minute. The average injection coating thickness is 40
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After demolding, as shown in Figure 3, the parts that will not become conductive circuits were masked with masking tape, and then placed in an electroless plating bath and plated with copper to a thickness of 40 μm. The adhesion between the pattern and the molded product was confirmed. A wiring board with a high brightness and a clear pattern was obtained.

[Effects of the Invention] The present invention produces a molded body having a layer of a plating precursor material on the surface having plating nuclei for electroless plating in a mold, so that the adhesion between the plating precursor material and the molded body is improved. It is possible to obtain a highly reliable wiring board, especially a three-dimensional wiring board with a complicated shape.

[Brief explanation of the drawing]

1 and 2 are vertical schematic sectional views of a mold for explaining the present invention in detail. FIG. 3 is a schematic cross-sectional view of a wiring board on which a conductive circuit portion 5 is formed by electroless plating after masking the portion that will not become a conductive circuit portion with a mask material 4. FIG. FIG. 4 is a schematic cross-sectional view of the wiring board from which the mask material has been removed. 1... Molded body 3... Plating precursor material

Claims (1)

[Claims] 1. In a method for manufacturing a wiring board in which a conductive circuit portion is formed on the surface of a molded body serving as a substrate, a molded body having a layer of a plating precursor material having plating nuclei for electroless plating on the surface in a mold is manufactured. Then, after masking the part of the surface of the plating precursor material layer that does not become a conductive circuit part with a mask material, electroless plating is performed to form a conductive circuit part on the surface of the molded body. Law.