JPH04216884A - Adhesive composition for flexible printed wiring boards - Google Patents

Abstract

PURPOSE:To obtain the title composition which can be cured in a short time by heating at relatively low temperature and can minimize bleeding, by mixing a specified glycidyl compound with an acrylic elastomer containing functional groups, a curing agent and a radical polymerization initiator. CONSTITUTION:An acrylic elastomer having functional groups (e.g. an acrylic elastomer having epoxy groups) is mixed with a glycidyl compound having at least one epoxy group and at least one (meth)acrylamidomethyl group in the molecule, a curing agent (e.g. 4,4'-diaminodiphenylmethane) and a radical polymerization initiator to give the title composition. As the glycidyl compound, a compound of the formula (wherein R is H or CH3) is used. The above- mentioned composition can be cured in a short time, is excellent in adhesive power, resistance to soldering heat, resistance to reflowing, resistance to bleeding, etc., has long pot life, and is suitable particularly for the reinforcing plate of a flexible printed wiring board.

Description

Description: FIELD OF THE INVENTION The present invention relates to an adhesive composition suitable for bonding a reinforcing plate to a plastic film used in a flexible printed wiring board. [Prior Art and Problems] Conventionally, adhesives used for flexible printed wiring board substrates and flexible printed wiring board reinforcing plates have not been cured, as described in Japanese Patent Laid-Open No. 62-59683. This required high temperature and long heating times. [0003] Epoxy resins, acrylic resins, phenolic resins, etc. are used in this type of adhesive, and in order to obtain sufficient adhesive performance, aromatic polyamines, phenols, epoxy resins, etc. Because it uses resin, it had to be heated at high temperatures for a long time to harden. Moreover, these adhesives were unsuitable as adhesives for component mounting reinforcing plates and flexible printed wiring boards because of the large amount of adhesive flowing out. Means for Solving the Problems As a result of repeated studies on the above-mentioned problems, the present inventors found that an adhesive system containing at least one epoxy group and one acrylamide methyl group or methacrylamide methyl group By combining a functional group-containing acrylic elastomer (A) with a glycidyl compound (B) having a group, and also using a curing agent (C) suitable for them, especially an aromatic polyamine and a radical polymerization initiator (D), The present inventors have discovered that the curing speed can be increased, heat curing can be performed at a relatively low temperature for a short period of time, and the flow-out property can be extremely reduced, and the present invention has been completed. That is, the present invention comprises: (1) an acrylic elastomer (A) having a functional group, and a glycidyl compound (B) having at least one epoxy group and one acrylamide methyl group or methacrylamide methyl group in one molecule; An adhesive composition for flexible printed wiring boards containing a curing agent (C) and a radical polymerization initiator (D),
■ The curing agent (C) is an aromatic polyamine,
It is also characterized in that the exothermic decomposition temperature of the radical polymerization initiator is 25 to 120°C, and it is also characterized in that the glycidyl compound (B) has the following structure: and [Formula 1] (wherein, R represents a hydrogen atom or a methyl group) 00
08]■ The amount of the radical polymerization initiator (D) is 0.1 to 10 p based on the solid content of the glycidyl compound (B).
It is also characterized by being hr, and furthermore, 0009]■
Acrylic elastomer (A) and glycidyl compound (
Another feature is that the blending ratio of B) is in the range of 1/1 to 10/1 in terms of solid content weight ratio. Further, the present invention will be specifically explained. As the acrylic elastomer (A) used in the present invention, acrylic elastomers known per se can be used, but
In general, it is a polymer containing one or more acrylic esters or α-substituted acrylic esters as a main component and containing at least one functional group as a crosslinking point, or Included are polymers in which at least one group-containing monomer is (grafted) copolymerized with the above-mentioned main component monomer. More specifically, the acrylic elastomer (A) contains (a) one or more of acrylic esters or α-substituted acrylic esters in a large proportion, and (b) epoxy esters. Examples include acrylic elastomers copolymerized with monomers having one or more functional groups selected from the group consisting of (c) carboxyl groups, and (d) hydroxyl groups. Specific examples of the monomers (a) to (d) will be shown below. Examples of the acrylic ester or α-substituted acrylic ester (a) include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and octyl acrylate. Examples of the epoxy group-containing monomer (b) include glycidyl ethers such as vinyl glycidyl ether and allyl glycidyl ether; glycidyl (meth)acrylates and the like. [0014] Furthermore, carboxyl group-containing monomer (c)
Examples include (meth)acrylic acid, itaconic acid, maleic acid, and maleic anhydride. Further, as the hydroxyl group-containing monomer (d), 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, ethylene glycol dimethacrylate,
Examples include dimethacrylates of polyhydric alcohols such as propylene glycol dimethacrylate and polyethylene glycol dimethacrylate; alkoxyalkyl acrylates such as methoxymethyl acrylate; and the like. Furthermore, other vinyl monomers such as vinyl chloride, vinylidene chloride, styrene, methacrylonitrile, vinyl acetate, etc. may also be copolymerized depending on the case. Specifically, the acrylic elastomer (A) includes Arontac S-1511L, S-1511X, S
-1015, S-1017 (manufactured by Toagosei Kagaku Co., Ltd.)
, Noxtite PA-501, PA-502 (manufactured by Nippon Mectron); Teisan Resin WS022, WS02
3, SG51, SG80, SG90 (manufactured by Teikoku Kagaku Co., Ltd.), AR-51 (manufactured by Nippon Zeon Co., Ltd.), and the like. These can be used alone or in combination of two or more. [0016] The acrylic elastomer (A) may have a functional group such as an epoxy group, a carboxyl group, a hydroxyl group, or a hydroxyl group. Preferably. The glycidyl compound (B) used in the present invention is not particularly limited, but generally contains 1 glycidyl compound per molecule.
Any epoxy group and one acrylamide methyl group or methacrylamide methyl group may be used. The curing agent (C) used in the present invention is not particularly limited, but may include commonly used curing agents such as aliphatic polyamines, aromatic polyamines, acid anhydrides, imidazole, hydrazide, and dicyandiamide. . In particular, 4,4'-diaminodiphenylmethane,
Preferably, aromatic polyamines such as 4,4'-diaminodiphenyl ether and 4,4'-diaminodiphenyl sulfone are used. Radical polymerization initiator used in the present invention (
Examples of D) include organic peroxides such as lauroyl peroxide, benzoyl peroxide, and cumyl peroxide. The blending ratio of the acrylic elastomer (A) and the glycidyl compound (B) is as follows:
)/glycidyl compound (B) is preferably in the range of 1/1 to 10/1, preferably in the range of 2/1 to 6/1. If the blending ratio of the acrylic elastomer (A) is less than 1/1, the soldering heat resistance will decrease. On the other hand, if the ratio is more than 10/1, the adhesive strength will decrease. Furthermore, a curing agent (C) and a radical polymerization initiator (D) are added to the main components (A) and (B), but at this time, the addition of the curing agent (C) The amount is preferably epoxy equivalent to 1/2 epoxy equivalent. If the amount of curing agent (C) added is less than 1/2 epoxy equivalent, a sufficient degree of curing will not be obtained, leading to a decrease in soldering heat resistance. Moreover, even if more than the epoxy equivalent is added, gas mainly composed of S is generated in the soldering heat resistance test, which is not desirable. The amount of the radical polymerization initiator (D) added is 0.1 to 10 p based on the solid content of the glycidyl compound (B).
Preferably it is hr. When the amount of the radical polymerization initiator (D) added is 0.1 phr, it is difficult to shorten the curing time, and when it is 10 phr or more, the adhesive strength and soldering heat resistance are insufficient. As the solvent used in the adhesive composition of the present invention, methyl ethyl ketone, acetone, toluene, dioxane, methyl cellosolve acetate, ethylene glycol monomethyl ether, etc., and mixtures thereof can be used. [0024] Various additives such as plasticizers, antioxidants, anhydrous silica, fine inorganic fillers such as aluminum hydroxide, etc. can be appropriately added to the adhesive composition of the present invention. Needless to say. [0025] In order to apply the adhesive composition of the present invention to a film or a reinforcing plate, the constituent components of this adhesive composition are first mixed by a known mixing means, then dissolved in a solvent, and applied in a solution state. do. In this case, after being applied to either one of the objects to be adhered, the adhesive is laminated and cured using an arbitrary heat curing means. For example, the above-mentioned coated material is dried in a hot air oven to dry the solvent or precured to form a B-stage product, and then combined with other adherends and heated to dry the solvent.
5kg/cm2 to 40kg/cm2 at 0 to 180℃
A method of heat-pressing is used at a pressure of . Alternatively, the coating may be continuously coated and dried, then continuously passed through a heated roll, heat-pressed and integrated, and then post-heat-cured. Examples of reinforcing plates to which the adhesive composition of the present invention is applied include aluminum plates, silicon steel plates, paper phenol laminates,
Examples include glass epoxy laminates, polypropylene, and polyethylene. In addition, the film to which the adhesive composition of the present invention is applied is not particularly limited as long as it is a polymer film, but refers particularly to those used for FPC, such as polyimide film, polyester film, polyether ketone film, polyether sulfone film. , ultra-thin laminates, etc. [Function] The adhesive composition of the present invention can bond a plastic film and a reinforcing plate used for flexible printed wiring boards at a relatively low temperature in a short time, and at the same time can It has a long life and has the advantage of extremely little run-off. In addition, the adhesive composition of the present invention has properties required for adhesion between plastic films and reinforcing plates used in flexible printed wiring boards, such as adhesive strength, solder heat resistance, run-out resistance, and long pot life. Provide all satisfactory adhesives. [0028] Next, the present invention will be explained in detail with reference to Examples, but these are not intended to limit the scope of the present invention. Example 1 Acrylic elastomer SG90 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., trade name) was mixed with methyl ethyl ketone/toluene 1/
93.5 parts of a 20% by weight solution dissolved in a mixed solvent of 1, 9.375 parts of Kaneka AXE (manufactured by Kaneka Chemical Co., Ltd., trade name; glycidyl compound of [Chemical formula 1] with R=H), aromatic As a polyamine, 1.875 parts of 4,4'-diaminodiphenylmethane (manufactured by Sumitomo Chemical Co., Ltd., trade name) was added, and further, as a radical polymerization initiator, 0.189 parts of lauroyl peroxide (manufactured by Kayaku Akzo Co., Ltd.) was added. was added to create a viscous adhesive. Thereafter, the solid content was coated on release paper to a thickness of 40 μm, and dried at 120° C. for 5 minutes to prepare a B-stage film. After that, it was transferred to an Al reinforcing plate and bonded to a flexible printed wiring board at 170℃ x 5
It was pressed under the condition of 10 kg/cm2. However, after pressing, do not cool with water to room temperature. Example 2 SG80 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., trade name) was used as the acrylic elastomer, and 4,4 was used as the aromatic polyamine.
The same procedure as in Example 1 was carried out except that '-diaminodiphenyl ether was used. Example 3 WS023 (manufactured by Teikoku Kagaku Sangyo Co., Ltd., trade name) was used as the acrylic elastomer, and 4,
The same procedure as in Example 1 was carried out except that 4'-diaminodiphenylsulfone was used. Comparative Example 1 The same procedure as in Example 1 was carried out except that no radical polymerization initiator was used. Comparative Example 2 The same procedure as in Example 1 was carried out except that the amount of radical polymerization initiator added was 1.407 parts. The method for evaluating the characteristics of the flexible printed wiring board (FPC) obtained according to the example (comparative example) is as follows. ■ Adhesive strength: Compliant with JIS C6481. ■ Solder heat resistance: Compliant with JIS C6481. ■ Reflow resistance: inlet temperature 300℃, outlet temperature 35℃
F at a speed of 1 m/min in a far-infrared heating furnace at 0°C.
Pass through the PC. Visually observe the results. ■ Resistance to bleeding: A 0.8 mm hole is made in the FPC, and the amount of adhesive bleeding after pressing is measured. The results are shown in [Table 1]. [Table 1] *1: Pot life is the period until the viscosity reaches twice its initial value. Effects of the Invention As explained above, the adhesive composition for flexible printed wiring boards of the present invention can be cured in a short time, and has excellent adhesive strength, soldering heat resistance, reflow resistance, and resistance. It has excellent flowability and a long pot life, and has a good balance of these properties, so it is particularly suitable for use as a reinforcing plate for flexible printed wiring boards.

Claims (1)

[Scope of Claims] [Claim 1] An acrylic elastomer (A) having a functional group; and at least one epoxy group in the molecule;
characterized by containing a glycidyl compound (B) having acrylamide methyl groups or methacrylamide methyl groups, a curing agent (C) and a radical polymerization initiator (D),
Adhesive composition for flexible printed wiring boards. [Claim 2] The curing agent (C) is an aromatic polyamine,
The adhesive composition for a flexible printed wiring board according to claim 1, wherein the radical polymerization initiator has an exothermic decomposition temperature of 25 to 120°C. [Claim 3] The glycidyl compound (B) is the following [Chemical formula 1]
2. The adhesive composition for flexible printed wiring boards according to claim 1, having the following structure. [Claim 1] (In the formula, R represents a hydrogen atom or a methyl group.) [Claim 4] The amount of the radical polymerization initiator (D) is 0.1 to 0.1 to the solid content of the glycidyl compound (B). 10ph
The adhesive composition for a flexible printed wiring board according to claim 1, wherein the adhesive composition is r. 5. The blending ratio of the acrylic elastomer (A) and the glycidyl compound (B) is 1/1 to 1 in solid weight ratio.
Claim 1 or 3 characterized in that the range is 0/1.
An adhesive composition for a flexible printed wiring board as described in .