JPH03285389A - Manufacture of multilayer wiring board - Google Patents

Abstract

PURPOSE:To reduce the generation of blisters in inner layer circuits and improve production efficiency by arranging metallic foil sheets for an outer layer on the upper and/or lower surfaces of a required number of inner layer members via nonwoven fiber-based prepregs and applying laminate molding processing to a resulting laminate sandwiched between metal mold plates. CONSTITUTION:Metallic foil sheets for wiring are laminated on the upper and/or lower surfaces of a required number of prepregs. Electric circuits are formed on the metallic foil sheets of a laminated plate for an electric machine to obtain a laminate. A required number of the laminates are sandwiched between metal mold plates and laminate molding processing is applied to the laminates to obtain a required number of wiring boards. A base material is required to be a nonwoven fiber composed of inorganic fibers made of glass, asbestos or the like or organic fibers made of polyester or the like. The number of the nonwoven fiber for use is favorably 1-3. As the metallic foil sheet for the outer layer, the foil sheet of copper, size or the like alone, its alloy or complex is used and preferably 0.018-0.07mm thick. The metal mold plate is made of iron, aluminum, copper, nickel, zinc or the like alone, its alloy or complex and preferably 6-15mm thick.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multilayer wiring board used in electrical equipment, electronic equipment, computers, communication equipment, etc.

[Conventional technology]

A conventional multilayer wiring board consists of a laminate in which outer layer metal foil is arranged on the upper and/or lower surfaces of the required number of inner layer materials via prepreg, which is sandwiched between inner plates, and multiple sets are stacked one on top of the other, and then the outermost layer is placed on top of the other. Laminate molding is performed by sandwiching the mold plates, but since there is an inner plate between the mold plates, the total number of laminates interposed between the mold plates has to be reduced, which has the disadvantage of low productivity. there were. However, if the inner plate is removed and only the laminate is stacked in multiple sets and sandwiched between mold plates for lamination molding, the circuit part of the inner layer material will float on the surface of the metal foil for the outer layer, making it unusable as a multilayer wiring board. do not have. For this reason, attempts have been made to suppress the floating of the inner layer circuit by using copper foil with an aluminum carrier as the metal foil for the outer layer, but this is not sufficient and requires an extra step of removing the aluminum. Attempts have also been made to perform laminated molding at low pressures, but there has been a problem in that the incidence of molding defects is high.

[Problem that the invention seeks to solve]

As described in the prior art section, in order to improve the productivity of multilayer wiring boards, there are many drawbacks to using copper foil with an aluminum carrier as the metal foil for the outer layer or performing lamination molding at low pressure. The present invention has been made in view of the above-mentioned problems in the conventional technology, and its object is a method for manufacturing a multilayer wiring board that can efficiently produce a multilayer layout board with less occurrence of lifting of inner layer circuits. Our goal is to provide the following.

[Means for solving problems]

In the present invention, a required number of laminates in which outer layer metal foils are disposed on the upper and/or lower surfaces of inner layer materials via a non-woven base material prepreg are sandwiched between mold plates and laminated to form a required number of wiring boards. The manufacturing method for multilayer wiring boards is characterized by the fact that the non-woven fabric base material prepreg prevents the inner layer circuit from floating, and since no inner plate is used, the number of laminates between the mold plates is increased. The present invention will be described in detail below.

Inner layer materials used in the present invention include woven fabrics, nonwoven fabrics, cloaks, paper, and other base materials made of inorganic fibers such as glass and asbestos, organic synthetic fibers such as polyester, polyamide, polyvinyl alcohol, and acrylic, and natural fibers such as cotton. Materials include phenolic resin, cresol resin, epoxy resin, unsaturated polyester resin, melamine resin, polyimide, polybutadiene, polyamide, polyamideimide, polysulfone, polyphenylene sulfide, polyphenylene oxide, polybutylene terephthalate, polyether ether ketone, fluororesin, etc. An electric circuit is formed on the metal foil of a laminated board for electrical equipment, which is made by integrally disposing metal foil on the upper and/or lower surfaces of the required number of prepregs impregnated with resin, such as alone, a modified product, or a mixture, and dried. As the resin for impregnating the nonwoven fabric base material prepreg, resins used for prepregs used for manufacturing electrical laminates can be used as they are, and in addition, calcium carbonate, aluminum hydroxide, talc/clay, silica, magnesium carbonate, Inorganic powder fillers such as titanium oxide, fiber fillers such as glass fibers, polyester fibers, polyamide fibers, bulbs, and wood flour can be included in the resin, but inorganic fibers such as glass and asbestos can be used as base materials. It is necessary to use a nonwoven fabric made of organic fibers such as polyester, polyamide, and polyvinyl alcohol. The amount of the impregnated resin relative to the base material is preferably 40 to 60% by weight (hereinafter simply referred to as %) by weight after drying. The resin used for the nonwoven fabric base material prepreg may be the same as the resin used for the inner layer material, or may be of a different type. Further, the number of sheets to be used is not limited either, but 1 to 3 sheets is preferable. As the metal foil for the outer layer, a single, alloy, or composite metal foil of copper/aluminum, iron, nickel, zinc, etc. is used, and the thickness is not particularly limited, but it is preferably 0.018 to 0.07 mm. The mold plate may be made of iron, aluminum, copper, nickel, zinc, etc. alone, alloy, or composite mold plate, and the thickness is not particularly limited, but it is preferably 6 to 15 mm. The laminating and integrating means is preferably a press, a multistage press, etc., but is not particularly limited.

The present invention will be explained below based on examples.

[Example 1] Epoxy resin with a thickness of 0.3 no. is applied to the upper and lower surfaces of an inner layer material formed by forming electric circuits on both sides of a 70 micron thick copper-clad laminate. Thirty sets of laminates each having a copper foil with a thickness of 0.018 mm interposed between one sheet of impregnated glass nonwoven fabric were sandwiched between stainless steel mold plates with a thickness of 10 mm, and a molding pressure of 30 kg/cdl, l 65
30 multilayer wiring boards were obtained by lamination molding at C for 120 minutes.

[Comparative Example 1] The same inner layer material as in the example was coated with a 0.0-thick layer on the upper and lower surfaces through two sheets of 0.1-thick epoxy resin-impregnated glass cloth prepreg.
One set consisted of a laminate with 18 mm copper foil sandwiched between 2 mm thick stainless copper inner plates.
Ten sets were sandwiched between stainless steel mold plates having a thickness of 10 mm and laminated and molded at a molding pressure of 30 kg/cm at 165° C. for 120 minutes to obtain 10 multilayer wiring boards.

[Comparative Example 2] Thirty multilayer wiring boards were obtained in the same manner as in Comparative Example 1, except that 30 sets of the same laminates as in Comparative Example 1 were laminated as they were without using an inner plate.

C Comparative Example 3] Thirty sets of the same laminate as in Comparative Example 1 were laminated as they were without using an inner plate, and 30 multilayer wiring boards were processed in the same manner as in Comparative Example 1, except that the molding pressure was 10 kg/d. I got it.

Table 1 shows the performance of the multilayer wiring boards of Examples and Comparative Examples 1 to 3.

Table 1 [Effects of the Invention] The present invention is constructed as described above. In the method for manufacturing a multilayer wiring board described in the claims, there is less occurrence of floating of inner layer circuits, and there is an effect that productivity can be improved.

Claims (1)

[Claims] (1) The required number of laminates in which metal foil for the outer layer is arranged on the upper and/or lower surfaces of the required number of inner layer materials are sandwiched between mold plates and laminated to form the required number of multilayers. A method for producing a multilayer wiring board, the method comprising obtaining a wiring board.