JPH01294785A - Adhesive for metal foil-clad laminate - Google Patents

Abstract

PURPOSE:To obtain the title adhesive excellent in solderingheat resistance and tracking resistance by adding an acid curing agent as a curing agent for amino resin to a resin composition comprising a polyvinyl butyral resin, an epoxy resin and an amino resin. CONSTITUTION:100 pts.wt. polyvinyl butyral resin, desirably, of a degree of butyralization of 60-70mol% and a degree of polymerization of 1500-2500 is mixed with desirably 10-40 pts.wt. epoxy resin which is desirably a phenolic epoxy resin or a mixture of this resin with a polyfunctional resin, desirably, 30-100 pts.wt. amino resin which is desirably an alkylated melamine resin, desirably, 0.1-1.0 pt.wt. acidic curing agent selected from between a hydrolyzable acid curing agent, desirably, an imidedisulfonic acid salt of formula I (wherein R1 is H or an alkyl) or a nitrilosulfonic acid salt and a thermalIy dissociable acid curing agent such as NH4Cl or ammonium sulfaminate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an adhesive for metal foil-clad laminates that is used for bonding metal foil and laminates when producing metal foil-clad laminates.

[Conventional technology]

BACKGROUND OF THE INVENTION As consumer electronic devices become smaller and more sophisticated, the printed wiring boards used therein tend to become more dense and ultra-fine.

Accordingly, metal foil-clad laminates used for printed wiring boards are required to be capable of high-density mounting. Additionally, tracking resistance has come to be required especially for devices to which high voltage is applied, such as televisions, from the standpoint of ensuring safety.

Conventionally, polyvinyl butyral resin and phenol resin, which are excellent in peel strength and soldering heat resistance, have been mainly used for adhesion between metal foil and laminate.

[Problem to be solved by the invention]

However, since this phenol resin is easily carbonized, it becomes easily conductive during a tracking property test, making it easy to form tracking and easily causing a fire, causing a decrease in tracking resistance. Therefore, the use of melamine resin or epoxy resin, which are materials that are difficult to carbonize, has been proposed in Japanese Patent Application Laid-open No. 116682/1982 as a material to replace the phenol resin. However, although the tracking resistance is improved by using a melamine resin or an epoxy resin, the soldering heat resistance is reduced.

In view of the above, an object of the present invention is to provide an adhesive for metal foil-clad laminates that improves tracking resistance without reducing soldering heat resistance.

(Means for Solving the Problems) The present invention is an adhesive for metal foil-clad laminates that meets the above-mentioned objectives, and includes a resin composition consisting of a polyvinyl butyral resin, an epoxy resin, and an amino resin, and a cured amino resin. It is characterized by the addition of an acidic curing agent as an agent.

The degree of butyralization and degree of polymerization of the polyvinyl butyral resin used in the present invention are not particularly limited, but the degree of butyralization is 60 to 70 mol%, and the degree of polymerization is 1500 to 2500.
Preferably. S-LEC BX as a specific resin
-1, BX-2, BX-55 (manufactured by Block Chemical Industry Co., Ltd., trade name), Denka Butyral 4000-2.5000-A, 6
000-C (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name) and the like. These resins may be used alone or in a mixture of two or more.

Epoxy resins used in the present invention include epoxy resins that are glycidyl ethers of phenols such as phenol novolak epoxy resins, cresol novolac epoxy resins, resol epoxy resins, and bisphenol epoxy resins (phenol epoxy resins) and glycidyl ester types. Epoxy resin, polymer epoxy resin,
Any epoxy resin can be used, such as halogenated epoxy resin, flexible epoxy resin, and polyfunctional epoxy resin, but phenolic epoxy resin or a mixture of phenolic epoxy resin and polyfunctional epoxy resin is resistant to soldering heat. This is preferable because it has a large effect of improving properties and adhesion. As a specific phenolic epoxy resin, Epicoat's 815.828.1001.1002.1
Bisphenol type epoxy resin such as 004.1007 (manufactured by Yuka Shell Epoxy Co., Ltd., trade name), Epicoat 1
Phenol novolak type epoxy resin such as 52.154 (manufactured by Yuka Shell Epoxy Co., Ltd., trade name), Epicoat 1
Examples include orthocresol novolak type epoxy resins such as B0S65 (manufactured by Yuka Shell Epoxy Co., Ltd., trade name). Examples of the polyfunctional epoxy resin include TEPIC (trade name, manufactured by Kaguchi Kagaku Co., Ltd.). These epoxy resins may be used alone or in a mixture of two or more.

Examples of the amino resin used in the present invention include melamine resins, benzoguanamine resins, alkyl etherified melamine resins obtained by alkyl etherification of these resins, and alkyl etherified benzoguanamine resins, and alkylated melamine resins are preferably used. Specifically, methylated melamine resins MW-30, MS-001, MX-002, M
X-705, mixed etherified melamine resin MX-40
8 and benzoguanamine resin BL-60 (both manufactured by Sanso Chemical Co., Ltd., trade names).

The mixing ratio of the above resins is not particularly limited, but preferably 10 to 40 parts by weight of epoxy resin and 30 to 1 part by weight of amino resin to 100 parts by weight of polyvinyl butyral resin.
00 parts by weight to form a resin composition.

The acidic curing agent used as the curing agent for the amino resin of the present invention is 0.1-
It is preferable to add 1.0 parts by weight.

As the acidic curing agent used in the present invention, a hydrolyzable acidic curing agent that exhibits a curing action by hydrolyzing to produce an acid, such as the imidodisulfonate shown and the nitrilosulfonate shown below, is used. imidodisulfonic acid triammonium salt derivatives,
Catanite, Catanite A1 Catanite C1 Catanite U, Catanite P, and Catanite S (all manufactured by Nitto Kagaku Co., Ltd., trade names) are commercially available as triammonium nitrilosulfonic acid salt derivatives. Further, thermally dissociable acidic curing agents such as ammonium chloride, ammonium sulfamate, and zinc chloride, which dissociate with heat to generate acids, can also be used.

The adhesive material of the present invention can be obtained by adding and mixing an organic solvent to the above compounded materials as required.

The organic solvent is not particularly limited as long as it dissolves the above materials, but considering the adhesive application process, relatively inexpensive and low boiling point solvents such as methanol, acetone, toluene, and methyl ethyl ketone are used. This is desirable.

[Effect]

Amino resin, which is effective in improving tracking resistance, is less likely to undergo a co-condensation reaction with the phenol resin that is the base resin of the laminate, and methylol groups remain, so a decomposition reaction occurs when it is floated in a solder bath, resulting in solder smearing. I wake up. In other words, the soldering heat resistance is reduced. Therefore, it is thought that by curing the amine resin at the adhesive stage before hot-pressure molding the laminate, the gas generated between the metal foil and the laminate during laminate molding will be reduced, and the soldering heat resistance will be improved. It will be done.

〔Example〕

Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto.

Examples 1 to 3 Comparative Examples 1 to 2 Adhesives for metal foil-clad laminates were obtained by uniformly dissolving the resin compositions shown in Table 1 in a solvent. This adhesive was applied to a copper foil having a thickness of 35 μm using a roll coater, and was dried and cured to obtain an adhesive-attached copper foil having a thickness of 40 μm. Eight sheets of phenolic resin-impregnated base material were stacked on the adhesive side of this copper foil to form a laminate, sandwiched between stainless steel mirror plates, and heated to 160°C and 100kg/c+I! So 6
A copper-clad laminate was obtained by heat-pressing molding for 0 minutes. Table 1 shows the properties of this copper-clad laminate. In order to examine the storage stability of the adhesive, the adhesive was left at 25°C for 130 days, and then adhesive-coated copper foil and copper-clad laminate were manufactured in the same manner as above, and their properties were investigated.

Comparative Example 2 shows the characteristics when oxalic acid, which is a free acid, was used as the acidic curing agent.

Table 1 shows the solder heat resistance and copper foil peeling strength of Examples and Comparative Examples.
As is clear from the above, the soldering heat resistance of the present invention was good, and the peel strength of the copper foil did not deteriorate due to aging, confirming the superiority of the present invention.

〔Effect of the invention〕

The adhesive for metal-clad laminates of the present invention can improve the tracking resistance of metal-clad laminates without reducing their solder heat resistance, and has extremely great industrial value.

Claims (1)

[Scope of Claims] 1. An adhesive for metal foil laminates, characterized in that an acidic curing agent is added as a curing agent for the amino resin to a resin composition consisting of a polyvinyl butyral resin, an epoxy resin, and an amino resin. 2. The adhesive for metal foil laminates according to claim 1, wherein the amino resin is an alkylated melamine resin. 3. The adhesive for metal foil laminates according to claim 1 or 2, wherein the acidic curing agent is a hydrolyzable acidic curing agent or a thermally dissociable acidic curing agent.