JPH1060403A - Adhesive composition and production of multilayer printed-circuit board by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive composition capable of producing a multilayer printed circuit board having good in adhesive and reliability in a through hole connection by blending specific rubber particles with a curable resin capable of coating on a surface of a material to be coated without a solvent. SOLUTION: This adhesive composition is obtained by blending (B) cross- linked acrylonitrile-butadiene rubber particles with (A) a curable resin (preferably a liquid epoxy resin at a room temperature such as an epoxy resin of a bisphenol A type) capable of coating on a surface of a material to be coated without using 21 solvent. The component B is preferably obtained by cross- linking the acrylonitrile-butadiene rubber in an emulsion state after an emulsion polymerization. The acrylonitrile-butadiene rubber of 10-30wt.% acrylonitrile content is preferably used. The blending ratio of the component B based on the amount of the composition is preferably 5-20wt.%. A novolak type phenol resin is preferably used as the curing agent of the component A. If necessary, a plating catalyst is preferably blended therewith when the conductive circuit is formed on the surface by an additive method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an adhesive composition and a method for producing a multilayer printed wiring board using the adhesive composition.

[0002]

2. Description of the Related Art A multilayer printed wiring board is a printed wiring board having a conductor circuit layer in an inner layer in addition to a surface conductor layer. Multilayer printed wiring boards are manufactured by processing a metal-clad laminate to form a conductor circuit that forms the inner layer (referred to as an inner layer board), and then bonding and integrating the outer layer material to form a circuit on the outer layer material surface. Manufactured. When manufacturing a four-layer printed wiring board, a single wiring board having conductor circuits formed on both sides is used as an inner layer board, and a prepreg and a metal foil or a prepreg and a single-sided metal foil laminated board are laminated and molded on both sides. When manufacturing a multilayer printed wiring board having more conductor layers than four layers, a manufacturing method such as increasing the number of inner layer boards is employed. There is also known a method in which an adhesive layer containing an electroless plating catalyst is formed on the surface of an inner layer plate without using an outer layer material, and a conductive circuit is formed on the surface by an additive method to form a multilayer printed wiring board. As the outer layer material, a metal foil or a metal-clad laminate is used. However, recently, since it is required to make the printed wiring board thinner, there is a tendency to use a metal foil as the outer layer material. In addition, since copper foil is used as a metal foil except in special cases, it will be referred to as copper foil hereinafter, but is not limited to copper foil.

[0003] A glass cloth-based epoxy resin prepreg is used for adhesion between constituent members (referred to as constituent members when the inner layer plate and the outer layer material are collectively referred to). In the prepreg, since the solvent is volatilized in the manufacturing process and the resin is in the B stage, it flows by heating and fills the unevenness on the surface of the inner layer plate generated by the circuit formation, so that voids are not easily generated in the layer.

[0004]

However, since the prepreg contains a fiber base material, there is a limitation in reducing the thickness of the prepreg. In addition, since the undulation of the fiber base material appears on the outer layer material, there is a limit in smoothing the surface. Therefore, an attempt has been made to bond the components with each other using a curable resin that can be applied to the surface of the adherend without using a solvent. However,
If the curable resin alone is used to bond components to form a multilayer, the adhesiveness between the resin and the components and the reliability of through-hole connection are lacking. This is because the toughness of the curable resin alone is poor. Therefore, it was considered to mix rubber, but it was not possible to mix rubber in a solvent-free composition, and to uniformly disperse the rubber. Therefore, the varnish in which the curable resin composition was dissolved in a solvent was used to disperse the rubber. I had to let it. However, in order to remove the solvent of the varnish, a drying step is required, and if the solvent remains in the curable resin without being completely dried, the adhesion to the inner layer plate is reduced, and the heat resistance due to this is reduced. Reduction is a problem. The present invention provides an adhesive composition that can be applied to the surface of an adherend without a solvent, when the constituent materials are adhered to each other, the adhesiveness can be a multilayer printed wiring board having good through-hole connection reliability. The purpose is to provide.

[0005]

SUMMARY OF THE INVENTION The present invention is an adhesive composition comprising a crosslinkable acrylonitrile-butadiene rubber particle mixed with a curable resin that can be applied to the surface of an adherend without using a solvent.

[0006] A multilayer printed wiring board is manufactured by bonding and integrating components with each other using the adhesive composition.

When a conductive circuit on the surface is formed by the additive method, the adhesive composition layer is formed and cured on an inner layer plate on which the circuit is formed, and a circuit pattern is formed by electroless plating. To manufacture a multilayer printed wiring board.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The crosslinked acrylonitrile-butadiene rubber particles used in the present invention are minute high-molecular-weight crosslinked rubber particles having a primary average particle diameter of about 50 to 100 nm obtained by crosslinking acrylonitrile-butadiene rubber in an emulsion state after emulsion polymerization. . The presence or absence of modification with a functional group such as a carboxyl group, a cyano group, or an amino group is not important. From the viewpoint of adhesion and flexibility, it is preferable to use acrylonitrile butadiene rubber having an acrylonitrile amount of 10 to 30% by weight. The blending amount of the acrylonitrile-butadiene rubber particles is preferably 5 to 20% by weight in the adhesive composition. If the amount is less than 5% by weight, there is no effect on imparting toughness to the adhesive layer, and if it exceeds 20% by weight, the adhesive composition tends to be semi-solid.

[0009] As the curable resin which is the basis of the adhesive,
It is preferable to use an epoxy resin. Examples of the epoxy resin include bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol AF epoxy resin, bisphenol S epoxy resin, alicyclic epoxy resin, glycidyl etherified phenols, and diglycidyl ether of alcohols. And their halides and their hydrogenated products. Among them, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, hydrogenated bisphenol A which are liquid at room temperature
It is more preferable to use a type epoxy resin.

As a curing agent for the epoxy resin, a novolak type phenol resin is desirable. In addition to curing agents,
An inorganic filler is blended if necessary. When a conductive circuit on the surface is formed by the additive method, a plating catalyst serving as a deposition nucleus for electroless copper plating is contained in the adhesive, if necessary. As a plating catalyst, 8 in the periodic table of elements is used.
There is a simple substance, a salt, or an oxide of an element belonging to Group 1, 1B, or 2B. Elements belonging to Group 8, 1B or 2B in the periodic table of elements include copper, gold, silver, platinum, palladium,
Examples include iron, cobalt, and nickel. Above all,
Palladium is most preferred.

The plating catalyst is prepared by dispersing a powder in a resin, dissolving the resin by using a polar group of the resin, or depositing or depositing on a solid surface. The amount of the plating catalyst is 5 to 1 with respect to the total amount of the adhesive composition.
Preferably, it is in the range of 5% by weight.

Each component of the adhesive composition is kneaded and mixed to prepare a liquid mixture. At this time, it is preferable that the curing agent and the other components are not mixed but mixed at the time of use.

The obtained adhesive composition is applied to the surface of the inner layer plate on which the circuit has been formed so as to have a thickness of 10 to 100 μm. At this time, if there is a through hole in the inner layer plate, the hole is filled at the same time. After application, the temperature is
The adhesive is semi-cured by heating and curing for 15 minutes (B stage)
Then, copper foil or a single-sided copper-clad laminate for the outer layer is overlaid and heated and pressed.

When a conductive circuit on the surface is formed by the additive method, a release film is laminated in place of copper foil and heated and pressed to form a laminate with an adhesive containing an inner layer circuit, and the conductive circuit on the surface is formed by electroless plating. To form When depositing the electroless plating, the cured adhesive surface is chemically roughened to a shape suitable for bonding. As a roughening liquid used for chemical roughening, a chromium-sulfuric acid system, a chromium-sulfuric acid-sodium fluoride system, an alkali-permanganic acid system, a borofluoric acid-bichromic acid system, or the like can be used. Also,
The pattern is formed by screen printing of a plating resist or ultraviolet curing and development of a photomask.
These plating resists are performed before the chemical roughening process or after the chemical roughening process. The roughened laminate with the inner layer circuit-containing adhesive is immersed in an electroless plating solution to form a circuit pattern.

[0015]

【Example】

Preparation of adhesive composition Preparation of main agent Crosslinked acrylonitrile butadiene rubber particles (using XER-91 (trade name) manufactured by Nippon Synthetic Rubber Co., Ltd.) 8
Parts (parts by weight, hereinafter the same), 40 parts of bisphenol A type epoxy resin (YD-128 (trade name) manufactured by Toto Kasei Co., Ltd.), finely ground silica (Aerosil # 200 manufactured by Nippon Aerosil Co., Ltd. Name)) 2
Parts, 15 parts of aluminum hydroxide (using CL-310 (trade name) manufactured by Sumitomo Chemical Co., Ltd.), and palladium chloride added filler (Cat # manufactured by Hitachi Chemical Co., Ltd.) as a catalyst for electroless plating. 14 (trade name) were mixed while heating to 40 ° C. Preparation of curing agent Separately from the main agent, 12 parts of phenol novolak resin (using H400 (trade name) manufactured by Meiwa Kasei Co., Ltd.) and 0.1 part of 2-ethyl-4-methylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd.) 2E4MZ (trade name) was heated to 80 ° C. and mixed.

Example 1 The above-mentioned main agent and curing agent were melt-stirred and mixed at 70 ° C.
This is applied to the surface of an inner layer plate having a circuit pattern to be an inner layer circuit formed on both sides thereof so as to have a thickness of 40 μm.
C. for 12 minutes to form a semi-cured adhesive layer. Next, the surface of the adhesive layer was smoothed by buffing # 800, and a copper foil having a thickness of 18 μm was overlaid thereon.
It was heated and pressurized at 5 MPa and 170 ° C. for 15 minutes to be integrated. Next, through-hole formation, through-hole plating,
Processing was performed in the order of etching to form a conductor circuit and through-hole connection on the surface to obtain a four-layer printed wiring board.

Example 2 The above main agent and curing agent were melt-stirred and mixed at 70 ° C.
This was applied on the surface of an inner layer plate having a circuit pattern to be an inner layer circuit formed on both sides thereof so as to have a thickness of 40 μm.
Heating was performed at 0 ° C. for 15 minutes to form a semi-cured adhesive layer, and the surface of the adhesive layer was smoothed in the same manner as in Example 1. Two pieces of the inner layer plate with the adhesive obtained in this manner are stacked, and an 18 μm-thick release-treated aluminum foil (using Sepanium (trade name) manufactured by San Aluminum Industry Co., Ltd.) is used on the outer surface thereof. Place, 2.5MPa, 17
The mixture was heated and pressed at 0 ° C. for 15 minutes to be integrated. Next, a conductor circuit on the surface is formed by electroless plating according to a conventional method, and 6
A layer printed wiring board was obtained.

Comparative Example 1 A four-layer printed wiring board was obtained in the same manner as in Example 1, except that the crosslinked acrylonitrile-butadiene rubber particles in the base material were removed.

Comparative Example 2 Crosslinked acrylonitrile butadiene rubber particles were changed to uncrosslinked acrylonitrile butadiene rubber (PNR-1 (trade name) manufactured by Nippon Synthetic Rubber Co., Ltd.), and 35 parts of methyl ethyl ketone was added as a solvent. Then, the main agent and the curing agent were simultaneously mixed to form a varnish. This varnish was applied to the same inner layer plate as in Example 1, heated at 50 ° C. for 2 hours to remove the solvent, and then heated at 120 ° C. for 10 minutes. The same varnish was further applied thereon, heated at 50 ° C. for 2 hours, and then heated at 120 ° C. for 10 minutes to form an adhesive layer having a thickness of 40 μm. Thereafter, a four-layer printed wiring board was obtained in the same manner as in Example 1.

The multilayer printed wiring boards obtained as described above were examined for circuit adhesion (peeling strength), heat resistance, and through-hole connection reliability. Table 1 shows the results.

[0021]

[Table 1] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Example 1 Example 2 Comparative Example 1 Comparison Example 回路 Circuit adhesion 1.4 1.4 0.9 1 .5 Heat resistance No blistering No blistering No blistering No blistering Through-hole connection reliability ○ ○ × ○ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━━━

The test method was as follows. Circuit adhesion: The peel strength between the copper foil of the inner layer plate and the adhesive layer was measured according to JIS C6481. The test piece was polished from one side to expose the copper foil of the inner layer plate and used for the test. The numerical value in Table 1 is kN / m. Heat resistance: The state after immersion in a solder bath at 288 ° C. for 30 seconds was visually determined. 26 through-hole connection reliability test pieces
After immersion in oil of 0 ± 5 ° C. for 5 seconds, immersion in water of 20 ± 5 ° C. for 10 seconds, and further with a draining agent of 20 ± 5 ° C. (using Fluorinert (trade name) manufactured by Sumitomo 3M Limited) One cycle was to immerse for 20 seconds and then lift and hold at room temperature for 10 seconds. This cycle was repeated 100 times, and then the presence or absence of disconnection of the through-hole connection was inspected. In Table 1, ○ indicates that there is no disconnection, and X indicates that there is disconnection.

[0023]

According to the present invention, the adhesive composition can be made solvent-free, and by using this adhesive composition, a multilayer printed wiring board having excellent adhesion and reliability of through-hole connection can be obtained. Can be manufactured.

Claims (3)

[Claims] 1. An adhesive composition comprising crosslinked acrylonitrile butadiene rubber particles mixed with a curable resin that can be applied to the surface of an adherend without using a solvent. 2. A method for producing a multilayer printed wiring board, comprising bonding and integrating components using the adhesive composition according to claim 1. 3. A multilayer printed wiring, wherein a layer of the adhesive composition according to claim 1 is formed and cured on an inner plate on which a circuit is formed, and a circuit pattern is formed by electroless plating. Plate manufacturing method.