JPS5810877B2 - Kairoban no Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a surface layer consisting of a composition based on a thermally crosslinkable unsaturated polymer and an elastomer coexisting on a non-conductive insulating plate made of an organic compound or an inorganic compound. A circuit that is different from the conventional method of performing roughening treatment and plating activation treatment with noble metal nuclei, and then depositing and fixing metallic copper on the surface coating film in an autocatalytic plating bath to obtain a desired circuit. As a method of obtaining this, a laminate with copper foil on the surface, that is, a copper-clad laminate for printed circuits, is used, which mainly consists of a predetermined amount of paper or cloth impregnated with epoxy resin, phenolic resin, unsaturated polyester resin, etc., and an adhesive. It is manufactured by laminating layers of copper foil under heat and pressure, and the circuit is printed on the surface of the copper foil, and then the copper foil other than the circuit area is chemically etched away, and the wiring circuit is printed on the insulating board. A method of forming is being used.

However, this method using copper-clad laminates is wasteful because most of the copper foil on the insulating board is etched and discarded.
Moreover, the through-holes formed by drilling required additional metallizing treatment.

On the other hand, in contrast to such a method using a copper-clad laminate, a method of forming a circuit by directly plating metal on an insulating board and on the walls of a through-hole is gaining importance.

As mentioned above, this process forms a surface layer that can firmly adhere to the plated copper deposited on the insulating board, and then applies a metal resist to the surface layer other than the circuit area, while oxidizing chemical roughening is applied to the circuit area. The circuit is formed in an autocatalytic plating bath.

Whether printed circuit boards are manufactured using copper-clad laminates or chemical plating according to the present invention, after circuit formation, mounting is done in the process of inserting and solidifying component terminals, and soldering is not processed. Therefore, the surface layer is required to have excellent adhesion to both metals and insulating boards, as well as a high degree of heat resistance.Furthermore, the surface layer is required to have a high degree of heat resistance, and in addition, it is essential for circuit board applications to inhibit the dielectric properties of insulating boards. This should not be the case.As mentioned above, the surface layer is basically a composition that bonds the metal and the insulating plate, and may be expressed as an adhesive in the following description.

It is widely known that a graft copolymer (ABS resin) consisting of acrylonitrile, butadiene, and styrene can form a strong metal coating by chemical plating, and in recent years, it has been used as a graft copolymer (ABS resin) on plastics such as polypropylene resin and nylon resin. A method of forming chemically plated metal coatings with high peel strength has been discovered.

However, the resin film that is applied has insufficient heat resistance, so it is impossible to satisfy the soldering heat resistance required for circuit boards.

On the other hand, as an adhesive that can be provided to chemically plated circuit boards, a composition consisting of acrylonitrile butadiene, oil-soluble phenol, etc. (Japanese Patent Publication No. 48-24250), a composition consisting of acrylonitrile butadiene, oil-soluble phenol epoxy, etc. (Japanese Patent Publication No. 46-9843) There are also examples of compositions consisting of polychloroprene isocyanate (Japanese Patent Publication No. 46-1597), and together with many proposals for excellent chemical plating baths capable of depositing ductile metallic copper, chemical plating circuits He has made a major contribution to the advancement of the board.

However, although chemically plated circuit boards have many advantages in terms of circuit production, to the applicant's knowledge, they do not seem to be able to provide the same performance as conventional copper-clad laminates. be.

The reason for this is that there are limitations on materials that can achieve both adhesion with deposited plated copper and soldering heat resistance, and also limitations on materials that can achieve both adhesion, adhesive film physical properties, and dielectric properties. It is.

For example, acrylonitrile-butadiene copolymer has excellent adhesion to deposited plating copper due to its polar groups and chemical roughening properties; Even when a vulcanization reaction is performed in the presence of other substances, it is difficult to obtain satisfactory soldering heat resistance, and
Due to the low cohesive force and film elastic modulus of the adhesive layer, the hardness of the circuit board surface is low, and deposited plated copper may peel off at the adhesive portion, that is, adhesive cohesion peels off.

In addition, a method for manufacturing an adhesive-covered laminate for chemically plated printed circuits was proposed prior to this application.

(Unexamined Japanese Patent Publication No. 50-15876, Unexamined Japanese Patent Publication No. 50-185
(No. 71 Publication) That is, a one-stage manufacturing method in which thermopressure lamination of insulating boards and formation of an adhesive layer are performed at the same time, has excellent circuit board performance,
It has the advantage of greatly shortening the conventional manufacturing process, but when using an adhesive film, the adhesive film has low cohesive force and elastic modulus, or has blocking properties at the precure stage. It was necessary to improve the physical properties of the adhesive film in order to make handling of the adhesive film in the circuit board manufacturing process extremely difficult. On the other hand, for copper-clad laminates, for example, polyvinyl butyral resin/resol Adhesives with a composition containing type phenolic resin or epoxy resin are considered to be useful, and they have excellent copper foil adhesion and solder heat resistance, and can provide printed circuit boards without problems with dielectric properties. The agent has excellent film properties at the precure stage.

However, because chemical roughening is not sufficiently carried out and adhesion to deposited copper is extremely low, or precipitation itself does not occur, it cannot be applied to chemically plated circuits.

The present invention has been made in view of these points, and provides a method for manufacturing a circuit board with excellent circuit peel strength and soldering heat resistance. A surface layer of a composition consisting of epoxidized 1.2 polybutadiene, acrylonitrile butadiene copolymer, and a crosslinking agent required for crosslinking the epoxy component is applied to the insulating plate, and a sulfidic surface roughening treatment and plating activation using noble metal nuclei are applied. The method is characterized in that copper is precipitated and fixed on the surface coating film in an autocatalytic plating bath.

Epoxidation 1.2 Polybutadiene is a pendant polymer having epoxy groups and unsaturated groups in the main chain and side chains, with approximately 2 or more epoxy groups per molecule and approximately 10 or more unsaturated groups per molecule. A commercially available product manufactured by Nippon Soda KK has a molecular weight of about 1000 and an epoxy equivalent of about 200.

Epoxidized 1.2 Polybutadiene, for which Niraso PB, BF-1000, etc. can be used, has an epoxy group and an unsaturated group as crosslinking components, and is thermally oxidized by an epoxy crosslinking agent and an organic peroxide having radical catalytic ability, respectively. It is possible to crosslink.

However, as the adhesive component for chemical plating printed circuits of the present invention, it is not necessary to crosslink the unsaturated groups. Rather, in order to measure the roughening and oxidation effects in the chemical roughening process, the unsaturated groups are left and thermal crosslinking is not performed. Epoxidation 1.2 Cross-linking of polybutadiene and precipitation When examining the state of plated copper, we found that ■ When unsaturated groups are cross-linked using an organic peroxide, a small amount of Those with unsaturated groups remaining ~ Plating precipitation is insufficient and the plated copper layer is easily peeled off. On the other hand, ■ If unsaturated groups remain and the epoxy groups are cross-linked, the properties of the deposited plating are uniform. It has excellent adhesion, and the adhesive surface of the peeled copper layer is in an oxidized state.In addition, chemical roughening treatment was applied to the composition of epoxidized 1.2 polybutadiene and acrylonitrile butadiene copolymer. When we examined the surface of the adhesive, we found that the formation and increase of polar groups was remarkable, and for example, the relationship between the increased amount of ester groups and acid groups formed and the adhesive strength with the precipitated plated copper layer corresponded well based on IR tracking. In addition, this composition is easy to handle because there is no blocking at the precure stage, and the physical properties of the adhesive film after thermal crosslinking, such as the film elastic modulus, are better than conventional ones, which are mainly based on rubber vulcanization or further contain an inorganic filler. When compared to the epoxidized 1.2 polybutadiene/acrylonitrile butadiene composition of the present invention, the latter is several kg/mm20 kg/mm2, whereas the epoxidized 1.2 polybutadiene/acrylonitrile butadiene composition of the present invention has a
g/mm2 to 90 kg/mm2, and therefore can eliminate the tendency to scratch on the surface of conventional adhesives and can greatly improve plating defects caused by the above factors. It is.

However, the above-mentioned adhesion mechanism may be interpreted differently from the intermediate layer, but this does not, of course, limit the effects of the present invention.

The acrylonitrile-butadiene copolymer that can be used in the present invention is not particularly limited, and the polar groups and nitrile content that contribute to adhesive properties do not require a high nitrile copolymer, but rather have dielectric properties, In particular, from the requirements of dielectric voltage connection, it is desirable that the nitrile group content is about 33 or less, and as a commercially available product, for example, Nipole 14 manufactured by Nippon Zeon KK is used.
Brands such as 32J (33% tolyl group), Nipole 1072 (27% tolyl group) and Nipole DN-401 (19% tolyl group) can be used.In particular, brands such as Nipole 1072 brand, which has carboxyl groups in addition to nitrile groups as polar groups, can be used. is effective.Additionally, adding or subtracting alkylphenol or metal oxides such as zinc white or magneur to the acrylonitrile-butadiene copolymer can contribute to improving the physical properties of the copolymer or improving the adhesion to precipitated plated copper. However, it is not necessarily an essential element in the present invention. Rather, the factor that can fully exhibit the effects of the present invention is the composition ratio range of the epoxidized 1.2 polybutadiene and acrylonitrile butadiene copolymer. The weight ratio is preferably in the range of 80/20 to 30/70.

In other words, when the epoxidized 1.2 polybutadiene ratio is 80 or more, the paint film tends to flow from the time the adhesive solution is applied in the process of forming the adhesive film to the time when the paint film is precure, that is, B staged, while the precure state is However, if the adhesive is applied directly to the insulating board to form a coating film during the circuit manufacturing process, there will be fewer problems, but forming an adhesive film using the one-step method described above is not recommended. If the manufacturing of the insulating board and the formation of the adhesive coating are then performed simultaneously, the adhesive film is likely to be damaged.

On the other hand, if the epoxidized 1.2 polybutadiene ratio is less than 30, the effects of the present invention gradually decrease.

The epoxy crosslinking agent can be selected in the same manner as for general bisphenol type epoxy 7 resins or novolac type epoxy resins, but it is preferable to use acid anhydrides for crosslinking the epoxidized 1.2 polybutadiene in the present invention.

For example, hexahydrophthalic anhydride (H
PA), methylnasic anhydride (MNA),
DDSA
), and chlorendate quanhydride (HET
), tetrahydrophthalic anhydride (TH
A) Tetrachlorophthalic anhydride (TCA
), nadic anhydride (NA), and other commercial products can be obtained and used.

Further, when acid anhydride crosslinking is performed in the present invention, the amount of crosslinking agent added does not need to be equivalent to the epoxy group equivalent, but is preferably in the range of 0.1 to 0.6 moles to ensure sufficient crosslinking.

In the present invention, conventionally known processes can be applied to the stage of creating a circuit by chemical roughening and chemical plating.

Chemical plating generally involves the following steps: oxidative surface roughening.

For example, a roughening solution consisting of dichromate and sulfuric acid or fluoroboric acid is used.

This process creates microscopic roughness on the surface of the adhesive coating, and further oxidizes unsaturated groups to generate polar groups.

■ Sensitizing with an acidic solution of stannic chloride and activation with a solution of noble metal salts such as palladium chloride.

In this step, catalytic properties, which are the core of chemical plating, are imparted to the coating surface.

In the present invention, by uniformly dispersing the catalyst in the adhesive composition, that is, by using an adhesive containing a plating catalyst, it is possible to perform this step simultaneously with the previous oxidative surface roughening step. .

However, in this case, the coating surface turns black depending on the oxidation state of the catalyst palladium salt, which may be considered to impair the appearance of the circuit board surface. This can be completely reduced by mixing and dispersing.

Moreover, the inorganic filler is rather effective in promoting the formation of a roughened shape in the coating film during the roughening process.

■Immerse in an autocatalytic chemical plating solution to deposit metallic copper on the adhesive coating.

Generally, a thin layer of metallic copper is formed by chemical plating and then electroplated to create a circuit having a predetermined plating thickness.

Example 1 Epoxidized 1.2 Polybutadiene was Nippon Soda Kogyo's Niraso PB-BF-1000 (molecular weight about 1000, epoxy equivalent about 200), 68 parts by weight, acrylonitrile butadiene copolymer was Nippon Zeon Kogyo's Nipol D
Tolyl content 19% in N-401) 38.5 parts by weight, 18.9 parts by weight of chlorendate quanhydride (HET), 2400.13.5 parts by weight of hytanol manufactured by Hitachi Chemical Co., Ltd. as an alkylphenol, and 3.0 parts by weight of zinc white. Parts by weight were uniformly dissolved and dispersed in a mixed organic solvent of methyl ethyl ketone and toluene (60:40 by weight).

A sigma blade kneader was used for dispersion, and the viscosity of the adhesive was adjusted to 2500 CP/20°C.

The adhesive film was then coated onto a release film (Teflon manufactured by DuPont) using a roll coater and air-dried in a hot air circulation dryer with a wave flow rate of 10 m2/min at 120 DEG C. for 15 minutes to form an adhesive film with a thickness of 40 .mu.m.

Further, a predetermined amount of epoxy resin-impregnated paper and the adhesive film as an insulating board base material are laminated so that the adhesive films are on both surfaces of the insulating board base material, and a heating film is applied to the heating plate at a temperature of 165 to 165. 170℃ pressure 55~
A chemically plated insulating board for printed circuits having an adhesive layer on the surface was produced by hot-pressing lamination via a mirror plate under hot-pressing conditions of 60 kg/cm 2 and a holding time of 60 minutes.

The elastic modulus when the adhesive film is thermally crosslinked alone is 85 kg/mm2, and the elastic modulus is 85 kg/mm2.
There was no blocking at all during the drying stage.

For the purpose of performance testing as a chemically plated printed circuit board, chemical roughening, sensitizing, activating, and chemical plating were performed on the entire surface according to the following known example, and the final copper foil thickness was 35 μm. Then, the copper-plated insulation board taken out from the plating bath was dried for 50 minutes in a hot air dryer at 160°C.

The plated surface after drying had no plating defects such as blisters, surface roughness, or pinholes.

The peel strength of the copper foil was 1.6 kg/cm, and the soldering heat resistance at 260° C. was 50 seconds or more, as determined in accordance with JISC-4681.

Also, the dielectric voltage connection (1MHz/20℃) of the plated circuit board is 0.
It was 0340.

Example 2 Eboxidation 1.2 with a molecular weight of about 1000, an epoxy molecular weight of about 500, and a number of unsaturated groups in one molecular weight of about 17.
Polybutadiene and Nippon Zeon KK Bipol 1072 (
Add 14.8 parts by weight of chlorendate hydride (HET) to 100 parts by weight of a composition blended so that the ratio of carboquine-containing acrylonitrile butadiene copolymer (nitrile group: 27%) to 63767 by weight Example 1 using an adhesive uniformly dissolved and dispersed in a solvent
An insulating board for chemically plated printed circuits was prepared in the same manner as above, and chemically plated.

The copper foil peeling strength of this product is 1.7 kg/cm, 26
0℃ soldering heat resistance 50 seconds or more Dielectric loss tangent (1MHz/20
°C) was 0.0355.

Comparative Example An adhesive having a composition consisting of acrylonitrile butadiene copolymer, alkylphenol, and zinc white, that is, Example 1, but excluding epoxidized 1.2 polybutadiene and chlorentiic anhydride,
Even after precure, the adhesive film still blocked, and the film elastic modulus after hot pressing was only about 6 kg/mm2.
The adhesive-coated insulating board prepared in the same manner as in Example 2 had a low surface hardness and was easily scratched.

In addition, in chemical plating, the plating is deposited well, but when the copper foil is peeled off, the adhesive tends to peel off cohesively, and even when the copper foil is peeled off at the interface, the peel strength is 1.5 kg/cm.
It was less than .

In addition, the 260℃ soldering heat resistance is 30 to 6 until solder blisters.
It was observed that the adhesive layer was thermally softened after holding for about 0 seconds.

Further, the dielectric voltage contact (1 MHz) was 0.0520.

The chemically plated printed circuit board obtained according to the present invention has the following advantages.

■ Thermoplastic acrylonitrile butadiene whose main component is 1, 2 polybutadiene, which has epoxy groups that facilitate thermal crosslinking and unsaturated groups that contribute to adhesion of deposited plating in the main chain and side chains, and also has polar groups. The adhesion and solder heat resistance of the precipitation plating circuit are greatly improved by the composition coexisting with the copolymer.

■ The coexisting composition of thermally crosslinked epoxidized 1.2 polybutadiene and thermoplastic acrylonitrile butadiene copolymer has no blocking properties at the precure stage and has excellent film properties after thermally crosslinked, making it suitable for adhesive-coated insulation. It is easy to handle during the board manufacturing process, and is effective in suppressing surface scratches and plating defects in chemical plating.

■ Due to the coexisting composition of epoxidized 1.2 polybutadiene and acrylonitrile butadiene copolymer, dielectric properties are improved compared to chemically plated printed circuit boards using conventional adhesives based on acrylonitrile butadiene or other synthetic rubbers. Demonstrates excellent effects.

Claims (1)

[Claims] 1 A surface layer of a composition consisting of epoxidized 1.2 polybutadiene, acrylonitrile butadiene copolymer, and a crosslinking agent required for crosslinking the Epoquin component is applied on a nonconductive insulating plate made of an organic compound or an inorganic compound, and an oxidizing A method for manufacturing a circuit board, which comprises performing a surface roughening treatment and a plating activation treatment using noble metal nuclei, and then depositing and fixing metallic copper on the surface coating film in an autocatalytic plating bath.