JPH07326861A - Copper foil surface-treating agent - Google Patents

Abstract

PURPOSE:To enhance a copper foil in adhesion to epoxy resin or unsaturated polyester resin by a method wherein the copper foil is treated with a combination of gamma-glycidoxypropyltrimetoxysilane and gamma-methacryloxypropyl trimethoxy silane or the above combination loaded with imidazole silane. CONSTITUTION:Imidazole silane is a chemical compound possessed of both an imidazole group and an alkoxysilane group in a single molecule and represented by formulas I, II, and III, where R<1> is an alkyl group which is 1 to 20 in number of carbon or hydrogen atoms, R<2> is an alkyl group which is 1 to 5 in number of hydrogen or carbon atoms or vinyl groups, R<3> and R<4> are an alkyl group which is 1 to 3 in number of carbon atoms, and n denotes 1 to 3. When R<1> is an alkyl group which is 1 to 20 in number of hydrogen or carbon atoms in a general formula, imidazole silance produces an enough effect, but as imidazole silane deteriorates in adsorptivity to copper due to a steric hindrance with the increase in number of carbon atoms, it is more preferable that the number of hydrogen or carbon atoms is 1 to 5. It is undesirable that the number of carbon atoms exceeds 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treating agent for improving the adhesiveness of a metal surface, and more particularly to a surface treating agent for copper foil used for copper clad laminates for printed circuits.

[0002]

2. Description of the Related Art Copper clad laminates for printed circuits are manufactured by heating a copper foil to a prepreg obtained by impregnating a paper base material with a phenol resin or a prepreg impregnating a glass base material with an epoxy resin.
A printed circuit board for an electronic device is manufactured by forming a circuit network by etching by pressurizing and stacking the circuit network, and mounting an element such as a semiconductor device on the circuit network. In these processes, adhesion with a prepreg, heating, dipping in an acid or alkaline liquid, application of resist ink, soldering, etc. are performed, so that various performances are required for the copper foil. For example, the adhesiveness to the prepreg, the chemical resistance, etc. are mainly required on the side to be bonded to the prepreg, which is usually called the M surface (roughened surface, the same applies hereinafter), and the normal S surface on the opposite side of the M surface is required. The side called the surface (glossy surface, the same applies hereinafter) is mainly required to have heat resistance and moisture resistance. It is also required that the copper foils on both sides of the copper foil do not undergo oxidative discoloration during storage. In order to meet these requirements, a brass layer is formed on the M surface of the copper foil (Japanese Patent Publication No. 51-35711, 54, 54).
No. 6701), both surfaces M and S are subjected to chromate treatment, zinc-chromium group mixture coating treatment comprising zinc or zinc oxide and chromium oxide (Japanese Patent Publication No. 58-7077). . In recent years, demands for miniaturization of printed wiring boards have been increasing more and more, and in order to respond to the improvement of etching accuracy accompanying this, lower surface roughness (low profile) is also required for the M surface. But,
On the other hand, the surface roughness of the M-side brings about an anchor effect in bonding with the prepreg. Therefore, there is a trade-off relationship between the requirement of the low profile and the improvement of the adhesive force for the M-side, and the anchor effect due to the low profile is achieved. It is necessary to compensate for the decrease in the value by improving the adhesive force by another means.

A method of applying a silane coupling agent to the M surface has also been proposed as a means for increasing the adhesive force or as a means for increasing the adhesive force due to the above-mentioned low profile (Japanese Patent Publication No. 2-19994, Japanese Patent Publication No. 2-19994). Kai 63-1
83,178, and JP-A-2-26097). Examples of silane coupling agents of this type include vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and 2
-(3,4-epoxycyclohexyl) ethyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl)
-3-Aminopropylmethyldimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-
Aminopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane and the like are known ["Latest Technology of Polymer Additives", pages 120-134, CMC, 1988 1
Issued on the 6th of every month].

[0004]

However, since the printed circuit has been densified recently as described above, the characteristics required for the copper foil for the printed circuit used have become more and more severe. In addition, the above-mentioned silane coupling agent must be properly used depending on the type of resin to be bonded to the copper foil. For example, an epoxy-based or amino-based silane coupling agent is effective in the case of an epoxy resin, and a methacrylic-based or styryl-based silane coupling agent is effective in the case of an unsaturated polyester resin. The present invention can meet such requirements, that is, improve the adhesion between the copper foil surface and the resin, and in particular, use a specific silane compound effective for the adhesion between the copper foil and the epoxy resin or the unsaturated polyester resin. It is intended to provide a foil surface treatment agent.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a combination of γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane, and further addition of an imidazole-based silane. It has been found that the above combination improves the adhesiveness between the copper foil and the epoxy resin or the unsaturated polyester resin. The present invention has been made on the basis of such findings, and the gist thereof is (1) a copper foil surface treating agent containing γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane as an active ingredient, (2) A copper foil surface treating agent containing γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and imidazole silane as active ingredients. The imidazole silane, which is one of the active ingredients of the surface treatment agent of the present invention, is a compound having both an imidazole group and an alkoxysilyl group in one molecule, and has the following general formula (1):
It is represented by (2) and (3).

[0006]

[Chemical 1]

(However, in the general formula (1), (2) or (3), R ¹ is hydrogen or an alkyl group having 1 to 20 carbon atoms, R ² is hydrogen, a vinyl group or 1 to 5 carbon atoms. Alkyl group, R ³ and R ⁴ are alkyl groups having 1 to 3 carbon atoms,
n is 1 to 3) R ¹ in the general formula (1), (2) or (3) is
Hydrogen or an alkyl group having 1 to 20 carbon atoms exerts the effect of the present invention sufficiently, but as the carbon number increases, the adsorption capacity of imidazole-based silane to copper decreases due to steric hindrance. Is more preferably 1 to 5. When the number of carbon atoms is 21 or more, the ratio of the alkyl group in the molecule increases and the effect of the imidazole group or the alkoxysilyl group decreases, which is not preferable. R ² is hydrogen,
If the vinyl group or the alkyl group having 1 to 5 carbon atoms, the effect of the present invention is sufficiently exhibited, but hydrogen, vinyl group, methyl group, from the viewpoint of adsorption ability of imidazole silane to copper,
The ethyl group is more preferred. R ³ is an alkyl group having 1 to ³ carbon atoms, but a methyl group or an ethyl group is more preferable from the viewpoint of easy hydrolysis. When the number of carbon atoms is 4 or more, the hydrolyzability is lowered, which is not preferable. R ⁴ has 1 to 1 carbon atoms
3 is an alkyl group. When the number of carbon atoms is 4 or more, the ratio of alkyl groups in the molecule increases, and the effect of the imidazole group or alkoxysilyl group decreases, which is not preferable. If n is 1 to 3, the effect of the present invention is sufficiently exhibited, but as the number of alkoxysilyl groups in the imidazole-based silane increases, the number of hydrolyzable groups increases and the reactivity with other silane agents improves. Therefore, the larger the value of n, the better,
n = 3 is particularly preferred. The imidazole-based silane compounds (1), (2) or (3) used in the present invention are the imidazole compound represented by the general formula (4) and the general formula (5).
It can be manufactured by reacting with a γ-glycidoxypropylsilane compound represented by The reaction is expressed by the following equation.

[0008]

[Chemical 2]

(In the above formula, R ¹ is hydrogen or has 1 to 1 carbon atoms.
20 alkyl groups, R ² is hydrogen, vinyl group or 1 carbon atom
˜5 alkyl group, R ³ and R ⁴ are alkyl groups having 1 to 3 carbon atoms, and n represents 1 to 3) The details of the imidazole silane are described in Japanese Patent Application No. 5-186479. Gazette). In the copper foil surface treating agent of the present invention, the mixing ratio of γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane is 99: 1.
It can be used in the range of up to 1:99. The surface treatment agent of the present invention may be directly applied directly to the metal surface,
0.001 with water, alcohols such as methanol and ethanol, and solvents such as acetone, ethyl acetate and toluene
It is easy to apply by diluting to 10 to 10% by weight, preferably 0.01 to 6% by weight, and dipping a copper foil in this solution, or spraying this solution on the surface of the copper foil. preferable. If it is less than 0.001% by weight, the effect of improving the adhesiveness and solder heat resistance is small, and if it exceeds 10% by weight, the effect is saturated and the solubility is deteriorated, which is not preferable.

Another aspect of the surface treating agent of the present invention is the above-mentioned γ
The above-mentioned imidazole silane is further added to the mixed system of glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane. The amount of the imidazole silane added is preferably 0.001 to 10% by weight, more preferably 0.01 to 6% by weight when diluted with the above solvent. When added in an amount of 0.001% or more, the imidazole group acts as a catalyst for hydrolysis or condensation of the silane coupling agent, and even when the addition amount is large, it itself acts as a silane coupling agent, and the imidazole group and the copper foil. Shows a strong adsorptive property and therefore gives good results in terms of adhesiveness. However, if it exceeds 10% by weight, the effect is saturated and the solubility is deteriorated, which is not preferable.

The copper foil coated with the surface treatment agent can be dried, then bonded to a prepreg and heated and cured to form a copper clad laminate. In this case, an adhesive may be interposed between the copper foil and the prepreg depending on the type of prepreg. Examples of such an adhesive include those made of polyvinyl acetal resin, phenol resin, epoxy resin, or the like. A prepreg is made by impregnating a base material with a resin, and as a base material for such a copper clad laminate, there is used paper, glass, or a composite in which a glass cloth is used as the center and glass paper (glass nonwoven fabric) is used as the center. There is something called. As the resin with which these base materials are impregnated, there are phenol resin, epoxy resin, unsaturated polyester resin, polyimide resin, polysulfone resin, fluorine resin and the like. Particularly preferred prepregs are those obtained by impregnating a glass substrate such as glass fiber or glass cloth with an epoxy resin or an unsaturated polyester resin, or those obtained by impregnating the composite with an epoxy resin or an unsaturated polyester resin.

[0012]

【Example】

Preparation of adhesiveness evaluation sample After forming a brass layer on the roughened surface of electrolytic copper foil (thickness 35 μm),
The copper foil surface treatment agent shown in Table 1 was applied to the roughened surface of a copper foil (25 cm × 25 cm) coated with zinc or a zinc-chromium group mixture of zinc oxide and chromium oxide by a spray method. . After coating, it was dried at 150 ° C. for 5 seconds. Adhesiveness test 1 The adhesiveness evaluation sample was heat-pressed with a prepreg in which a glass substrate was impregnated with an epoxy resin to produce a copper-clad laminate. The normal peel strength of this copper clad laminate was measured by the method specified in JIS C6481. The results are shown in Table 1. Further, the copper foil of this copper-clad laminate was etched to form 0.2 mm wide circuit × 10 pieces, and the peel strength after immersion in boiling water for 2 hours was measured. The strength and the peel strength before boiling treatment were compared with each other. The difference was calculated, and it was divided by the latter to obtain the% obtained as the deterioration rate. The results are also shown in Table 1. For comparison, no surface treatment, 0.4% γ-
Glycidoxypropyrotrimethoxysilane aqueous solution, 0.
Adhesiveness was also tested by the same method for the one treated with 1% γ-methacryloxypropyltrimethoxysilane acetic acid aqueous solution (pH 5). The results are also shown in Table 1. As is clear from Table 1, the treating agent of the present invention has a superior peel strength after boiling as compared with the comparative example.

[0013]

[Table 1]

Adhesion Test 2 The above adhesive sample was heat-pressed with a prepreg impregnated with an unsaturated polyester resin to prepare a copper clad laminate. The normal peel strength of this copper clad laminate was measured by the method specified in JIS C6481. The results are shown in Table 2.
Shown in. Further, the copper foil of this copper-clad laminate was etched to form 0.2 mm width circuit × 10 pieces, and the peel strength after immersion in a 5% sodium hydroxide bath at 70 ° C. for 4 hours was measured,
Find the difference between the strength and the peel strength before alkali treatment,
The value obtained by dividing it by the latter was determined as the deterioration rate.
The results are also shown in Table 2. For comparison, the same is applied to those that are not surface-treated, 0.4% γ-glycidoxypropyltrimethoxysilane aqueous solution and 0.1% γ-methacryloxypropylmethoxysilane acetic acid aqueous solution (pH 5) treatment. The adhesion was tested by the method. The results are also shown in Table 2. As is clear from Table 2, the examples are comprehensively superior in adhesiveness to the comparative examples.

[0015]

[Table 2]

[0016]

As described above, by using the copper foil surface treating agent of the present invention, the adhesiveness between the copper foil and both the epoxy resin and the unsaturated polyester resin can be improved.

Claims (2)

[Claims] 1. A copper foil surface treating agent comprising γ-glycidoxypropyltrimethoxysilane and γ-methacryloxypropyltrimethoxysilane as active ingredients. 2. A copper foil surface treating agent comprising γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane and imidazole silane as active ingredients.