JPH01160090A - Adhesive for wiring board - Google Patents

Abstract

PURPOSE:To obtain an adhesive which is suitable for a highly dense multi-wire wiring board by constituting a particular epoxy resin, a finely divided particle silicon rubber with a weight part of 5 to 30 in reference to the epoxy resin with a weight part of 100, and a cross-linking agent. CONSTITUTION:An adhesive is produced by adding an epoxy resin where a molecular weight of 5000 or more to one with a molecular weight which is less than 5000 is changed from 10:90 to 90:10, by adding a finely divided particle silicon rubber where the diameter of particles having pts.wt. of 5 to 30 is 30mum or less, and by adding a cross-linking agent for mixing them in an organic solvent. Use of an insulation electric wire on the surface of an insulation substrate fixing wire allows the adhesive to be flexible since it includes a finely divided particle silicon rubber, reduces stylus pressure, and absorbs supersonic energy during laying wire.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an adhesive used for wiring boards (hereinafter referred to as multi-wire wiring boards) using insulated wires for necessary wiring patterns.

(Conventional technology) Multi-wire wiring boards are produced by forming an adhesive coating on an insulating substrate with an inner layer circuit formed thereon by laminating or coating it, and then running insulated wires using a numerically controlled wiring machine and simultaneously heating and melting it using ultrasonic vibrations. After gluing (hereinafter referred to as wiring) by
It is manufactured by laminating prepreg to fix an insulated wire, drilling a through hole across the wire, and forming an electroless plated metal layer on the inner wall of the hole.

Since this multi-wire wiring board uses insulated wires, it is possible for the wires to cross each other on the same plane, and the wiring capacity per layer is about twice that of a general printed wiring board. In addition, since the insulated wires are installed directly on the board, there is no need for a network like that of a general printed wiring board, and design changes are easy.

The conventional insulated wire used for this has a diameter of 0.10 to 0.1
It has a double structure in which a 6 mm copper wire is coated with polyimide resin, and then a nylon resin is applied as an adhesive layer to increase the adhesive strength of the wire. The adhesive coating film needs to be able to easily fix the insulated wire to the wiring 7, and have heat resistance and insulation properties. For this reason, adhesives are made of natural rubber or synthetic rubber with excellent adhesive properties as the main component, cross-linked with alkylphenol resin to increase tear resistance and insulation, and further mixed with epoxy resin and various fillers as appropriate. The use of agents was recommended in Japanese Patent Publication No. 45-21434 and Special Publication No. 1973-
Known by 2063.

(Problems to be Solved by the Invention) In recent years, in order to apply multi-wire wiring boards to electronic devices that have become increasingly dense, it has become necessary to perform wiring at a higher density than before. In other words, the wiring density of the conventional multi-wire wiring board was three wires per through hole with a depth of 2.54 mm, but in the future, a wiring density of five or more wires will be required. For this reason, the conductor diameter of insulated wires has traditionally been 0.
．． 0.08mm instead of 10-0.16mm
Must be as follows. Also, the wires must be routed in precise locations. Furthermore, when conventional adhesives are used, there is a problem in that connection reliability at high temperatures deteriorates due to heat generated by electronic components mounted on the multi-wire wiring board.

The present invention solves the above drawbacks and provides an adhesive suitable for high-density multi-wire wiring boards while maintaining or exceeding conventional electrical performance. .

(Means for Solving the Problems) The present invention is based on an epoxy resin having a molecular weight of 2 or more and a molecule i.
The ratio of epoxy resin less than 5000 is 10:90 to 90
: Epoxy resin in the range of 10 and a particle size of 30μ in 5 to 30 overlapping parts per 100 parts by weight of the epoxy resin.
The present invention relates to an adhesive for wiring boards characterized by comprising silicone rubber in the form of fine particles having a particle diameter of less than m and a crosslinking agent.

Insulating substrates that can be used in the present invention include all insulating substrates that can be used in conventional multi-wire wiring boards, such as glass cloth epoxy resin copper-clad laminates, glass cloth polyimide resin copper-clad laminates, etc. A power supply layer and a ground layer are formed by a known etching method, and prepregs such as glass cloth epoxy resin or glass cloth polyimide resin are laminated and cured by heating.

Among the components of the adhesive coating film according to the present invention, the epoxy resin with two molecules of M5000 or more is Epicoat 0L-53-L
-32,0L-53-BH-35 [molecular weight 55. 00
0), 0L-55-L-32,1255-HX-3
0 (molecular weight 70,000 or more) (Yuka Shell Epoxy Co., Ltd., trade name).

Or Phenotote YP-40 (molecular weight 20°000
), YP-50M (molecule i30.000), YP-5
0 (molecular weight 40.000) (Tobu Kasei Co., Ltd., trade name), or PKHH, PAHJ [molecular weight 40.000
] (Union Carbide Co., trade name) etc. can be used. Incidentally, these polymeric epoxy resins are commonly referred to as phenoxy resins.

In addition, as an epoxy resin with a molecular weight of less than 5,000,
Epicote 828, 834, 871, 872.1001
．． 1002.1003, 1004.1007 (Yuka Shell Epoxy Co., Ltd., trade name), D, E, R, 317
,330,33L 361.661.662.664
, 667.732.736. D, E, N, 431, 43
8.439.485 (Dow Chemical Company, trade name), etc.

In addition, brominated epoxy resins such as E, R, 511,542 (Dow Chemical Company, trade name).

It can also be used to impart flame retardancy.

As a commercially available particulate silicone rubber, X-52-5
94 (Shin-Etsu Chemical Co., Ltd., trade name).

As the crosslinking agent, a combination of a blocked isocyanate and an epoxy curing agent, or a combination of an alkylated melamine and an epoxy curing agent, etc. can be used, and among the former combination, the blocked isocyanate is as follows:
Coronate 2503.2507.2515. Coronate AP Stable, Millionate MS-50 (Japan Polyurethane Industry Co., Ltd., trade name), Fleran U1. U.T.

Death module AP stable, CT stable, BL
Iloo, BL1265. There are BL3175 (trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.), and as the epoxy curing agent, acid anhydrides, dicyandiamide, etc. can be used.

In addition, as the alkylated melamine in the latter combination, methylated melamine resin Melan 520.521
．． 522.523 (Hitachi Chemical Co., Ltd., trade name) or Melan 20, a butylated melamine resin. 2
2. 23. 25. 26. X65, X66 (
Hitachi Chemical Co., Ltd., trade name), etc. can be used, and the epoxy curing agent at this time is preferably a mixture of an imidazole derivative and an acidic organic compound to increase heat resistance, and commercially available products include 2E4. MZ-CNS (1
-cyanoenal-2-phenylimidazole trimellitate] (Shikoku Kasei Kogyo Co., Ltd. 2 product name).

In the present invention, these compositions are prepared by combining 2 epoxy resins with a molecular weight of less than 5000 and 10 epoxy resins with a molecular weight of 500 or more.
:90 to 90:10 epoxy resin, particulate silicone rubber with a particle size of 30 μm or less in 5 to 30 parts by weight to 100 parts by weight of the epoxy resin, and a crosslinking agent added to the mixture in an organic solvent. Mix to make adhesive. In addition, fillers such as mica, finely powdered silica, zirconium silicate, magnesium silicate, and white titanium, which are effective in adjusting the flow characteristics of the adhesive, are added as appropriate.

Additionally, an electroless plating catalyst is added to improve the adhesion of the plating to the inner walls of the through holes, etc. The organic solvent used is selected from methyl ethyl ketone, acetone, toluene, xylene, methyl isobutyl ketone, ethyl acetate, methyl cellosolve, cello acetate, dimethyl formamide, etc., or a combination thereof.

(Function) The adhesive film formed on the surface of the insulating substrate on which the insulated wires are fixed includes fine particles of silicone rubber, making it flexible and reducing the stylus pressure applied during wiring. Additionally, it can absorb ultrasonic energy during wiring. If the diameter of each particle is 30 μm or more, the adhesive coating becomes too soft to allow wiring, and the reliability of the connection between the metal on the inner wall of the through hole and the inner layer circuit decreases in the through hole portion. Furthermore, if the amount is less than 5 parts by weight based on 100 parts by weight of the epoxy resin, the flexibility of the adhesive coating cannot be obtained and there is no effect, and if it is 30 parts by weight or more,
The adhesive film becomes too soft and cannot be used for wiring.

Furthermore, since an epoxy resin with a molecular weight of less than 5,000 is used for this adhesive, the flexibility conventionally obtained with an organic solvent can be obtained with a reduced amount of the organic solvent. This reduces solvent volatilization in the wire and allows for constant absorption of stylus pressure and ultrasonic energy in the wire.

(Example) 1) Create a glue varnish with the composition shown below, apply it to a PET film (trade name, Tohcello Chemical Co., Ltd.), which is a transfer base material, so that the film thickness after drying is 150 μm, and heat it at 120°C.
This was dried for 15 minutes to create an adhesive sheet.

Composition of insulating varnish: Internal molecular weight of 100 parts by weight of epoxy resin: 5,000 or more; 70 parts by weight of pKHH (trade name, Union Car High 1-Co., Ltd.) Molecular weight: less than 5,000; - Epicoat 828 (Yuka Shell Epoxy Co., Ltd.,
20 parts by weight of DEN438 (Dow Chemical Company, trade name)
Parts by weight and for this.

Microparticulate silicone rubber; X-52-594 (Shin-Etsu Chemical Co., Ltd., trade name) 10
Parts by weight Crosslinking agent: 20 parts by weight of Blocked Isocyanate Desmodur BL1265 (Sumitomo Bayer Urethane Co., Ltd., trade name) Epoxy curing agent; 3 parts by weight of dicyandiamide (Wako Pure Chemical Industries, Ltd., trade name) Filler 1: Crystallite VX- X <Tatsumori Co., Ltd.

20 parts by weight of plating catalyst (trade name); 3 parts by weight of Cat #10 (trade name, Hitachi Chemical Co., Ltd.).

Organic solvent: Mix in 180 parts by weight of cellosolve acetate (trade name, Wako Pure Chemical Industries, Ltd.).

2) Trainise #2 on electrical annealed copper wire with a diameter of 0.10 mm
000 (Toshi Co., Ltd., product name) at a furnace length of 3 m and a furnace temperature of 3
00℃, baking speed 20m/min, baking number of 11 times is about 10
It was applied to a thickness of μm.

3) Glass cloth epoxy copper clad laminate MCL-E-168 (
The inner layer circuit is formed by etching the prepreg GEA-168N (Hitachi Chemical Co., Ltd., trade name) of glass fabric epoxy resin containing a plating catalyst.
(product name) is layered and heated and pressed to form an insulating substrate.

4) Attach the adhesive sheet created in 1) to the insulating substrate in 3).

5) Peel off the PET film for transfer and use a wiring machine to
) insulated wires are laid on the insulated board.

6) Glass fabric epoxy resin prepreg GEA-168
N (manufactured by Hitachi Chemical Co., Ltd., trade name) is superimposed on the component of 5) and laminated by heating and pressing.

7) Laminate Hitalesox S-500X-9 (Hitachi Chemical Co., Ltd., trade name), a polyethylene film with adhesive, as a plating mask on the component in 6), and drill holes where the through holes 7 should be. , immersed in electroless copper plating solution Hid-410 (Hitachi Chemical Co., Ltd., trade name).

A copper layer of about 40 μm was formed on the inner wall of the hole.

8) The plating mask was peeled off to obtain a multi-wire wiring board.

This multi-wire wiring board has 350 wires in design, and the fabric density is 4 wires/2.54m in the orthogonal direction.
The length of the insulated wire is approximately 40,000 points/piece, and the length is 1/2°54mm in the 45 degree direction.

As a result of creating a multi-wire wiring board through this implementation, there were no disconnections or short circuits, and no abnormalities were observed even after 20 cycles of hot oil testing. In addition, the effects of implementing 5 coats of adhesive are that the amount of organic solvent contained in the adhesive coating is small and the volatile components are low, so it is possible to provide a good environment for each worker, and the surface after coating is less sticky. It was easy to handle because there was no such thing.

(Effects of the Invention) As explained above, both the adhesive coating and the outermost layer of the insulation coating of the insulated wire have a ratio of epoxy resin with a molecular weight of 5,000 or more to epoxy resin with a molecular weight of less than 5,000 of 10:9.
Using an adhesive consisting of an epoxy resin in the range of 0 to 90:10, 5 to 30 parts by weight of fine silicone rubber with a particle size of 30 μm or less, and a crosslinking agent to 100 parts by weight of the epoxy resin, It is possible to provide an adhesive for multi-wire wiring boards that maintains or exceeds electrical performance, has a low probability of disconnection, and has excellent connection reliability.

Claims (1)

[Claims] An epoxy resin in which the ratio of an epoxy resin with a molecular weight of 5,000 or more to an epoxy resin with a molecular weight of less than 5,000 is in the range of 10:90 to 90:10, and a particle size of 30 μm or less in 5 to 30 parts by weight per 100 parts by weight of the epoxy resin. An adhesive for wiring boards characterized by comprising particulate silicone rubber and a crosslinking agent.