JPS5810878B2 - Kairoban no Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a surface layer consisting of a thermally crosslinkable composition based on an unsaturated polymer and coexisting with an elastomer on a non-conductive insulating plate made of an organic compound or an inorganic compound. The present invention relates to a method for obtaining a desired circuit by 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 of the composition in an autocatalytic plating bath.

Conventionally, as a method for obtaining such circuits, a laminate having copper foil on the surface, that is, a copper-clad laminate for printed circuits, has been used, and is mainly made of paper or cloth impregnated with epoxy resin, phenolic resin, unsaturated polyester resin, etc. The insulating board is manufactured by laminating a predetermined amount of copper foil with an adhesive layer and hot-pressing it, printing a circuit on the copper foil surface, and then chemically etching away the copper foil other than the circuit area. A method has been adopted in which a wiring circuit is formed on top.

However, with this method using copper-clad laminates, most of the copper foil on the insulating board is etched and discarded, which is wasteful, and additionally, the through-holes formed by drilling require metallizing treatment. there were.

On the other hand, in contrast to the method using copper-clad laminates, emphasis has been placed on a method in which circuits are formed by directly performing metal plating on the insulating board and on the walls of the through-holes.

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.

For printed circuit boards, whether using copper-clad laminates or chemical plating according to the present invention, after the circuit is formed, the terminals of the components are attached, and the soldering is processed during the consolidation process. Therefore, the surface layer must not only have excellent adhesion to both metals and insulating boards, but also a high degree of heat resistance, and furthermore, the surface layer must have a high degree of heat resistance, and in addition, it must have properties that inhibit the dielectric properties of insulating boards due to the nature of circuit board applications. Must not be.

As mentioned above, the surface layer is basically a composition that adheres 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 (ΔBS resin) consisting of acrylonitrile, butadiene, and styrene can form a strong metal coating by chemical plating.
Furthermore, in recent years, a method for forming a chemically plated metal coating with high peel strength on plastics such as polypropylene resin and nylon resin has been discovered.

However, such a resin film has insufficient heat resistance and is therefore completely unable 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 butadiene, oil-soluble phenol, epoxy, etc. (Japanese Patent Publication No. 45-9843) or a composition consisting of polychloroprene, isocyanate, etc. (Japanese Patent Publication No. 46-116)
97), and together with many proposals regarding excellent chemical plating baths capable of depositing ductile metallic copper, they have made a great contribution to the progress of chemically plated circuit boards.

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

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. be.

For example, acrylonitrile-butadiene copolymer has excellent adhesion to deposited copper due to its polar groups and chemical roughening properties, but has poor dielectric properties and
Even when a vulcanization reaction is performed in the coexistence of a phenolic resin or a metal oxide such as Zno, Mgo, etc., it is difficult to obtain satisfactory soldering heat resistance, and the cohesive strength of the adhesive layer Due to the low elastic modulus of the film, the hardness of the circuit board surface is low, and the deposited plated copper may peel off at the adhesive layer, that is, adhesive cohesion may peel off.

In addition, prior to this application, a method for manufacturing an adhesive-covered laminate for chemically plated printed circuits was proposed (Japanese Patent Application Laid-Open No. 15876-1587).
(Japanese Patent Laid-Open No. 50-18571), a one-stage manufacturing method that simultaneously performs hot field lamination of insulating plates and forming an adhesive layer, has excellent circuit board performance and greatly shortens the conventional manufacturing process. However, when using an adhesive film, the adhesive film has a low cohesive force and a low elastic modulus, or has blocking properties at the precure stage. From this point of view, it was necessary to improve the physical properties of the adhesive film to make it extremely difficult to handle.

On the other hand, for copper-clad laminates, for example, adhesives containing polyvinyl butyral resin, resol type phenolic resin, or epoxy resin are considered useful, and they have excellent copper foil adhesion and soldering heat resistance, and have excellent dielectric properties. It is possible to provide printed circuit boards without any problems, and the adhesive has excellent film properties at the pre-cure 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 1.2 polybutadiene, graft rubber, and acrylonitrile butadiene copolymer is applied on an insulating plate, and an oxidative surface roughening treatment and a plating activation treatment with noble metal nuclei are performed, and then,
The method is characterized in that metallic copper is deposited and fixed on the surface coating film of the composition in an autocatalytic plating bath.

A butadiene polymer whose polymer chain mainly consists of 1.2 bonds is a butadiene homopolymer that does not have a functional group at the end of the molecule, and a butadiene homopolymer that has a primary hydroxyl group at both ends of the main chain.
, ω polybutadiene glycol, α, ω polybutadiene dicarboxylic acid having a carboxyl group and the third
Maleation by adding maleic anhydride to the carbon position 1.2
polybutadiene maleated 1,2 polybutadiene,
It is an addition derivative such as epoxidized 1.2 polybutadiene to which oxirane oxygen has been added, and all of them have an unsaturated group of about 10 or more in the main chain, and are commercially available products such as Nippon Soda K.
There are various brands of Nitso PB made by K, and the molecular weight is 1000 to 4.
000 is used.

Although the unsaturated groups in the main chain or side chains can be thermally crosslinked, it is not necessary to crosslink the unsaturated groups in the adhesive component for chemically plated printed circuits of the present invention.

Rather, in order to measure the effects of roughening and oxidation in the chemical roughening step, a method is used in which unsaturated groups remain and thermal crosslinking is carried out mostly at the molecular ends or branched functional groups.

For example, when examining the crosslinking of epoxidized 1.2 polybutadiene and the state of precipitated plated copper, it was found that: ■ When unsaturated groups are crosslinked using an organic peroxide, plating remains on a small amount of unsaturated groups. Deposition is insufficient and the plated copper layer is easily peeled off.

On the other hand, (2) When the unsaturated groups remain and the epoxy groups are crosslinked, the properties of the deposited plating are uniform and the adhesion is excellent, and the adhesive surface of the peeled copper layer remains in an oxidized state.

Furthermore, when we examine the surface of an adhesive that has undergone chemical roughening treatment for a composition in which epoxidized 1.2 polybutadiene coexists with acrylonitrile and butadiene copolymer, we find that the formation and increase of polar groups is remarkable, such as IR It was found that there was a good relationship between the increase in the amount of ester groups and acid groups produced by tracking and the adhesive strength with the deposited plated copper layer.

What should be emphasized in the chemical plating composition of the present invention is that the roughening shape can be easily adjusted in the chemical roughening process,
Moreover, together with the formation of polar groups, the effect contributing to adhesion can be fully exerted.

This surface roughening is achieved by adjusting the dissolution properties of each component in the composition, and is particularly noticeable in compositions consisting mainly of polybutadiene consisting of 1°2 bonds and graft rubber.

Graft rubber is a graft copolymer with natural rubber or synthetic rubber as the backbone polymer, and is a copolymer obtained by polymerizing various monomers using a radical catalyst in a solution or latex.The graft monomers include methyl methacrylate and acrylonitrile. , acrylamide, vinyl acetate, styrene, etc. are used.

Commercial products such as Hevea Blass MG-30 and Hevea Plus MG-49, which are natural rubber grafted with methyl methacrylate, are available from Itochu Corporation KK.

This natural rubber/methyl methacrylate graft copolymer is noticeably eluted in oxidizing roughening solutions, but it has no advantage as a chemical plating composition when used alone due to deterioration of physical properties or poor adhesion to deposited plating. Although it cannot be found, chemical roughening occurs in a short period of time in a composition in which 1.2 is uniformly dispersed in polybutadiene, and the roughened shape is uniform over the entire roughened surface, indicating that there is no adhesion to the deposited plating. The properties are superior to either 1.2 polybutadiene or natural rubber/methyl methacrylate alone.

This seems to be because the anchoring effect that contributes to adhesion of the roughened shape is sufficiently achieved.

By the way, when examining the dissolution of the coating film composition with respect to the chemical roughening solution by examining the change in weight over a given period of time, the ratio of retention rates is as follows:
Retention rate for crosslinked 1.2 polybutadiene alone is 90, and for the phenol vulcanization composition of acrylonitrile-butadiene, it is approximately 60.
, is about 20 for natural rubber/methyl methacrylate graft copolymer, and in a composition consisting of 1.2 polybutadiene and the graft copolymer, the elution retention rate can be easily adjusted to 30 to 80 by changing the composition ratio, and chemical roughness It is possible to greatly reduce the process required for conversion.

In addition, when observing the surface condition after chemical roughening using a scanning electron microscope, it was found that a single layer of free polymer was formed on the roughened surface with acrylonitrile butadiene composition, and especially in the state of excessive roughening, plating precipitation This occurs even in a porous polymer layer, and in such a porous region the adhesion of the deposited plating is quite low, resulting in cohesive peeling of the composition.

On the other hand, in the composition of the present invention in which 1,2 polybutadiene and graft rubber or acrylonitrile and butadiene coexist, the kraft rubber constituent components dissolve in a short period of time. It is not roughened to a free state, and therefore the entire layer of the composition does not exhibit a porous free state.

In addition, (1) a composition consisting of 2-polybutadiene and graft rubber has excellent dielectric properties, and as a surface composition of an insulating plate, has dielectric properties equivalent to or higher than that of the insulating plate itself, and also contains acronitrile and butadiene. The deterioration of the dielectric properties is slight even in the above cases, and the dielectric properties of the insulating plate having the surface layer of the composition are hardly inhibited.

Moreover, 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 film elastic modulus, are compared to conventional systems that are mainly rubber vulcanized or systems that further contain inorganic fillers. In the latter case, the amount is several Kg/mm2 to 20 Kg/mm2, whereas in the composition of the present invention in which 1.2 polybutadiene and graft rubber or acrylonitrile-butadiene coexist, the amount is 20 Kg/mm2 to 90 Kg/mm2.
Therefore, it is possible to eliminate the tendency of scratches on the surface of conventional adhesives, and to greatly improve plating defects caused by these factors.

However, the above-mentioned interpretation of the adhesion mechanism may lead to a different interpretation from that of the interlayer, but of course this does not limit the effects of the present invention.

Therefore, the acrylonitrile-butadiene copolymer that can be used in the present invention does not need to be particularly limited, and the polar groups and nitrile content that contribute to adhesion do not require a high nitrile copolymer, but rather have dielectric properties, especially the nitrile content. From the requirements of dielectric loss tangent, the nitrile group content is desirably 33 or less, and commercially available products include, for example, Nipole 14 manufactured by Nippon Zeon Industries.
32J has 33% tolyl group), Nipole 1072 has 27% tolyl group), Nipole DN-401 has 19 tolyl groups)
Brands such as Nipole 1072, which has a carboxyl group in addition to a nitrile group as a polar group, are particularly effective.

It has also been found that adding alkylphenol or metal oxides such as zinc white, magnesia, etc. to the acrylonitrile-butadiene copolymer and vulcanizing it contributes to improving the physical properties of the copolymer and improving its adhesion to precipitated copper. It is not necessarily an essential element in the present invention.

1.2 In a composition consisting of polybutadiene and graft rubber, or in a composition in which acrylonitrile/butadiene coexists, it is desirable that the amount of kraft rubber added is about 50% or less by weight; A desirable range of weight ratio is 80/20 to 30/70.

In other words, when the amount of graft rubber is large, the chemical oxidation of 1.2 polybutadiene or acrylonitrile-butadiene is not sufficiently carried out, although the roughening shape is sufficiently formed due to the roughening and elution properties of the graft rubber component. This is because it tends to be insufficient to make it work.

In addition, in compositions in which acrinitrile and butadiene coexist, the weight ratio with 1.2 polybutadiene is 80/20 ~
The reason why 30/70 is a preferable range is as follows.

In other words, when the 1.2 polybutadiene ratio is 60 or more, in the process of forming an adhesive coating, the coating tends to flow from the time the adhesive solution is applied until the coating is precure, that is, B staged, while the precure In the circuit board manufacturing process, it is too hard and prone to cracking.
There are few problems when applying the adhesive directly onto the insulating plate to form a coating, but the above-mentioned one-step method, especially after forming the adhesive film, is recommended for manufacturing the insulating plate and forming the adhesive coating. If this is done at the same time, the adhesive film is likely to be damaged.

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

When using epoxidized 1.2 polybutadiene as 1.2 polybutadiene, the epoxy crosslinking agent can be selected in the same manner as for general bisphenol-type epoxy resins or novolac-type epoxy resins. It is desirable to use an acid anhydride for crosslinking.

For example, hexahydrophthalic anhydride (H
PA), methylnasic anhydride (MNA),
Dodicinyl succinic anhydride (DDSA)
), chlorendic anhydride (HET), tetrahydrophthalic anhydride (THA),
Tetrachlorophthalic anhydride (TCA),
Commercially available products such as Nagic anhydride (NA) can be obtained and used.

Further, when acid anhydride crosslinking is carried out 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 in sequence:

■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 acidic solutions of stannic chloride and activation with solutions 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 uniformity of the roughened shape of the coating film in the chemical roughening process.

■ Deposit metallic copper on the adhesive coating by immersing it in an autocatalytic chemical plating solution.

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 1.2 Niraso P manufactured by Nippon Soda Kogyo as polybutadiene
1.2.5. weight part,
As an acrylonitrile butadiene copolymer, Nivol DN-401 manufactured by Zeon Industries has a tolyl content of 19%) 30
．． 5 parts by weight, chloride quanhydride (HE
T) 18.1 parts by weight, a group consisting of Hitachi Chemical's Hytanol 2400.13.0 parts by weight and 3.0 parts by weight of zinc white as an alkylphenol in a mixed organic solvent of methyl ethyl Kent and toluene (60:40 by weight) was uniformly dissolved and dispersed in the liquid.

A sigma blade kneader was used for dispersion, and the viscosity of the adhesive was adjusted to 35000P/20°C.

The adhesive film was then applied onto a release film (Teflon manufactured by DuPont) using a roll coater, and after air drying, an adhesive film having a thickness of 40 μm was prepared at 120° C. for 15 minutes in a hot air circulation dryer with an air flow rate of 10 m 3 /min.

Further, a predetermined amount of epoxy resin-impregnated paper and the adhesive film were stacked together as an insulating board base material so that the adhesive film formed on both surfaces of the insulating board base material, and triacetyl cellulose was used as a heat press release paper. Apply the film at a heating plate temperature of 165-170℃ and a pressure of 55-60Kg/cm2.
．． A chemical plated insulating board for printed circuits having an adhesive layer on the surface was produced by hot-pressing lamination via a mirror plate under heat-pressing conditions with a holding time of 60 minutes.

In addition, the elastic modulus when the adhesive film is thermally crosslinked alone is 75 Kg/mm2,
There was no blocking at all at the 10 minute drying stage.

For the purpose of performance testing as a chemically plated printed circuit board, chemical roughening, sensitizing, activation, and chemical plating were performed on the entire surface according to the following known example to obtain the final thickness of the copper foil. The copper-plated insulation board was taken out from the plating bath and dried for 60 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 determined in accordance with JISO-6481 to be 1.7 kg/cm, and the soldering heat resistance at 260° C. was 50 seconds or more.

In addition, the dielectric loss tangent (1MEHz/20℃) of the plated circuit board is 0.
．． It was 0340.

The chemical roughening conditions were as follows: chromium sulfuric acid mixed solution at 40°C for 10
~15 minutes was sufficient.

Example 2 Epoxidation 1,2 with a molecular weight of about 1000, an epoxy equivalent of about 500°, and a number of unsaturated groups per molecular weight of about 17.
Polybutadiene and maleated 1°2 polybutadiene (Nisso PB/BN-1000 manufactured by Nippon Soda KK) and Hevea Plus MG-49 (grafting rate 4) as craft rubber.
9%) and Composition 10 in a weight ratio of 58:11:21.
0 parts to 1 part chloride quanhydride (HET)
Using a composition in which 48 parts by weight was added and uniformly dissolved and dispersed in an organic solvent, an insulating board for a chemically plated printed circuit was prepared in the same manner as in Example 1, and chemically plated.

The copper foil peeling strength of this product is 1.7Kg/cm, 26
0℃ soldering heat resistance 50 seconds or more dielectric voltage contact (1MHz/20
°C) was 0.0330.

Comparative Example With 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 chloride quanhydride, the adhesive film remained intact even after precure. The elastic modulus of the film after blocking and hot pressing was only about 6 Kg/mm2, and the adhesive-coated insulating plates prepared in the same manner as in Examples 1 and 2 had low surface hardness and were easily scratched.

In addition, chemical plating deposition tends to cause adhesive cohesion and peeling when peeling off the copper foil, which is performed well, and even when peeling at the copper foil interface, the peel strength was less than 1.5 kg/cm.

In addition, the 260℃ soldering heat resistance is 30~30℃ until solder blisters.
After holding for about 50 seconds, it was observed that the adhesive layer softened due to heat.

Further, the dielectric loss tangent (1 MHz) was 0.0520.

The chemical plated printed circuit board obtained by the present invention has the following advantages.

■ By coexisting acrylonitrile and butadiene in a composition consisting of polybutadiene and graft rubber, which mainly consist of 1,2 bonds, the hardness of the surface layer is sufficiently high, and chemical roughening is easily carried out, making it possible to bond the deposit-plated circuit. Excellent heat resistance and soldering heat resistance.

■ The composition consists of a thermally crosslinkable polymer and an elastomer component, and the surface layer has no blocking during the precure stage and has excellent film properties after thermal crosslinking, making it easy to handle in the manufacturing process of adhesive-coated insulating boards. Furthermore, it is effective in suppressing scratches on the surface layer and plating defects in chemical plating.

(1) Since the above composition has excellent dielectric properties for both 1,2 polybutadiene and graft rubber, a chemically plated printed circuit board with excellent dielectric properties can be obtained, and the drawbacks of conventional chemically plated printed circuit boards can be largely overcome. It is something to be solved.

Claims (1)

[Claims] 1. On a non-conductive insulating plate made of an organic or inorganic compound, a surface layer with a composition of 1,2 polybutadiene, graft rubber and acrylonitrile butadiene copolymer is applied, followed by oxidative surface roughening treatment and noble metal core treatment. A method for producing a circuit part, which comprises performing a plating activation treatment, and then depositing and fixing metallic copper on the surface coating film of the composition in an autocatalytic plating bath.