JPH09316178A - Prepreg and copper clad laminate using the same - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a prepreg having improved adhesion to a copper foil, and a copper foil laminate using the prepreg. SOLUTION: The following general formulas (1) and (2) are used as a curing accelerator.
Alternatively, a prepreg characterized in that a base material is impregnated with an epoxy resin composition containing imidazole silane represented by (3) or a mixture thereof, and is dried and semi-cured. Embedded image (However, R ¹ is hydrogen, a vinyl group or an alkyl group having 1 to 5 carbon atoms, R ² is hydrogen or an alkyl group having 1 to 20 carbon atoms, and R ³ and R ⁴ are alkyl groups having 1 to 3 carbon atoms. Group, n is 1-3)

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a prepreg in which a base material is impregnated with an epoxy resin composition containing a specific curing accelerator, and a copper clad laminate obtained by laminating the prepreg and a copper foil and curing them.

[0002]

2. Description of the Related Art Among copper clad laminates as printed wiring boards, epoxy resin laminates are produced by impregnating a glass base material with an epoxy resin varnish and heating and drying the prepreg. It is manufactured by stacking a plurality of sheets and, if necessary, stacking metal foils such as copper foils, and heating and pressing the metal foils to form a laminate. And
The epoxy resin varnish used in the production of such an epoxy resin-based laminate is one in which dicyandiamide is blended in the epoxy resin as a curing agent, and 2-ethyl-4-methylimidazole is blended and prepared as a curing accelerator. It is common.

The epoxy resin generally contains a bisphenol A type epoxy resin (including a halogenated type) as a main component. In order to improve the heat resistance of the glass epoxy laminate, the bisphenol A epoxy resin as the main component is used. An appropriate amount of phenol novolac type epoxy resin, cresol novolac type epoxy resin, or multifunctional epoxy resin is blended.

On the other hand, in order to increase the adhesive strength between the copper foil and the base resin, the copper foil surface in contact with the base resin is provided with a granular copper layer by electrodeposition to roughen the surface (concavo-convex) and anchor. It is common to have an (anchor) effect.

However, in recent years, the miniaturization of electronic and electric equipment products has been remarkably progressed, so that the printed wiring boards used have become thinner and the circuit patterns thereof have become thinner. Therefore, metal foils such as copper foils are being thinned and made into a low profile in order to cope with it, and it is becoming difficult to maintain and increase the adhesive strength between the copper foil and the base resin.

[0006]

In order to further increase the adhesive strength between the copper foil and the base resin, the copper foil surface in contact with the base resin is provided with a granular copper layer by electrodeposition to roughen the surface (unevenness). It is known that a further anchoring effect can be obtained and a high adhesive strength can be provided by further increasing the degree of formation. However, printed wiring boards using a copper clad laminate as a starting material are manufactured by etching using a solution such as cupric chloride when forming the pattern, so anchoring particles (anchor particles) that have sunk into the epoxy resin are removed. Therefore, overetching is likely to occur and an excessive undercut occurs in the desired wiring pattern,
The pattern disconnection rate and defect rate increase. Also, if the etching degree is suppressed, anchor particles (anchor particles) will be added to the base material.
However, stains, discoloration of the base material, and movement of the printed wiring board often cause migration.
Therefore, maintaining the adhesiveness by physically roughening the copper foil surface
There is a limit to improvement.

Under the above circumstances, the present invention maintains / increases the adhesive strength between the copper foil and the base resin even when the metal foil such as the copper foil is thin and has a low profile. It is an object of the present invention to provide a prepreg with improved adhesiveness such as that and a copper clad laminate using the same.

[0008]

As a result of intensive studies, the present inventors have improved the adhesiveness between a copper foil and an epoxy resin substrate by selecting a specific imidazole silane-based curing accelerator for epoxy resin. The inventors have found that they can be achieved and have completed the present invention.

That is, the present invention relates to (1) the following general formulas (1), (2) or
(3) A prepreg characterized in that the substrate is impregnated with an epoxy resin composition containing imidazole silane or a mixture thereof represented by, and is dried and semi-cured.

[0010]

Embedded image

(However, R ¹ is hydrogen, a vinyl group or an alkyl group having 1 to 5 carbon atoms, and R ² is hydrogen or 1 carbon atom.
To 20 alkyl groups, R ³ and R ⁴ are alkyl groups having 1 to 3 carbon atoms, and n is 1 to 3) (2) A copper foil is arranged on one or more prepregs according to claim 1 and laminated to cure. The present invention relates to a copper clad laminate characterized by being made.

The prepreg of the present invention can be manufactured by impregnating a base material with an epoxy resin varnish containing the above-mentioned curing accelerator by a conventional method and drying it to a semi-cured state. The curing accelerator for the epoxy resin used in the prepreg of the present invention is represented by the above formulas (1) to (3), and among them, R ¹ is preferably hydrogen, methyl, ethyl, undecyl or heptadecyl because of easy synthesis. , R ² is preferably hydrogen, methyl or vinyl, and R ³ or R ⁴ is preferably methyl or ethyl.

Regarding the synthesis method of these, Japanese Patent Laid-Open No. 5-18
No. 6479. Even when it is obtained as a mixture of imidazole silanes represented by the above formulas (1) to (3) by this synthetic method, it is advantageous to use it in the form of a mixture without any need for separation.

The epoxy resin used in the prepreg of the present invention is not particularly limited and is a curable epoxy compound or epoxy polycondensate having more than one epoxy group in one molecule. Any that can be used can be used.

Examples of such epoxy resins include diglycidyl ether compounds of bisphenols such as bisphenol A and bisphenol F (bisphenol type epoxy resins), diglycidyl ethers of polyalkylene oxides such as polyethylene oxide and polypropylene oxide (aliphatic compounds). (Epoxy resin) or side chain or main chain modified with rubber, urethane, polyether, polyester or other flexible resin, phenol novolac, cresol novolac glycidyl ether compound (novolac type epoxy resin), or polybutadiene And the like, such as an epoxidized product of a conjugated diene polymer. As a solvent for epoxy resin varnish,
For example, acetone, methyl ethyl ketone, methyl cellosolve, ethyl cellosolve, propyl cellosolve, methyl isobutyl cellosolve, dimethylacetamide, dimethylformamide, methanol, ethanol, toluene,
From xylene, etc., they can be used alone or as a mixture. The resin concentration of the epoxy resin varnish is arbitrarily set according to the amount of resin impregnated into the substrate.
Further, if necessary, a monoepoxy compound reactive diluent can also be used.

In the epoxy resin composition used in the prepreg of the present invention, it is important to use the above-mentioned specific imidazole silane as a curing accelerator, but other curing agents known as curing agents for epoxy resins are also used. Agents and curing accelerators can also be used in combination.

Examples of such curing agents or curing accelerators include guanidine-based curing agents such as dicyandiamide, dihydrazide-based curing agents such as adipic acid dihydrazide, isophthalic acid dihydrazide and dodecanoic acid dihydrazide as curing agents for epoxy resins. It is possible to use a phenolic hardener such as phenol novolac, an acid anhydride hardener such as methyltetrahydrophthalic anhydride, an amine hardener such as diaminodiphenylmethane, or an imidazole hardener such as 2-ethyl-4-methylimidazole. it can. Of these, dicyandiamide is particularly preferable. Further, as a curing accelerator, imidazoles such as 2-ethyl-4-methylimidazole, tertiary amines such as benzyldimethylamine, aromatic phosphines such as triphenylphosphine, and Lewis acids such as boron trifluoride monoethylamine. And 2-ethyl-4-
Methylimidazole is preferred.

The amount of the curing accelerator used in the prepreg of the present invention is not particularly limited, but the epoxy resin 1
It is usually used in an amount of 0.1 to 5 parts by weight, preferably 0.1 to 3.0 parts by weight, based on 00 parts by weight. The curing accelerator is 0.
If the amount is less than 1 part by weight, the adhesiveness is not improved, and if the amount exceeds 5 parts by weight, the effect is saturated.

If desired, a silane coupling agent may be added to the epoxy resin varnish used in the prepreg of the present invention as an adhesion improver. By adding a silane coupling agent, the adhesive strength to a metal can be particularly improved. Examples of such a silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, and N-β.
(Aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, γ-
Mercaptopropyltrimethoxysilane, N-β- (N
-Vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane-hydrochloride and the like.

The base material to be impregnated with the epoxy resin varnish for forming the prepreg of the present invention is, for example, glass fiber, glass woven cloth, glass non-woven cloth, cloth,
Paper, aramid fiber base material, etc. are used.

The prepreg of the present invention is manufactured by impregnating the base material with an epoxy resin varnish and then drying.
This step itself can also be performed according to a conventional method. In this step, the solvent is removed from the prepreg by evaporation after the impregnation and the curing reaction of the epoxy resin is further promoted to some extent to form a so-called B stage. The heating conditions for the B stage are, for example, 100 to 160 ° C. and 3 to
20 minutes is enough. Then, a copper foil is superposed on this prepreg and is heated and pressed to be cured, whereby a copper-clad laminate having the copper foil firmly adhered thereto can be formed. This step can also be performed by a conventional method. That is, a required number of prepregs are stacked, copper foils are stacked on both upper and lower surfaces or one surface of the prepregs, and the prepregs are inserted into a high pressure press.
It is possible to heat and pressurize at 190 ° C. and 30 to 50 kg / cm ² to cure the epoxy resin prepreg of the B stage to the C stage, and to bond each layer of the prepreg and the copper foil together to form a copper clad laminate. . Various types of copper foil can be used, for example, JTC
Foil, JTCS foil (both are Nikko Gould Foil Co., Ltd.)
Is preferred. In the present invention, the use of the specific imidazole silane-based curing accelerator can improve the adhesiveness between the copper foil and the prepreg. The reason for this is not clear, but since it has an imidazole group that accelerates the curing of the epoxy resin in the molecule and an alkoxysilyl group that promotes the adhesion between the copper foil, each acts on the interface between the resin and the copper foil. As a result, it is estimated that the adhesiveness is improved.

[0022]

Next, the present invention will be specifically described with reference to examples.

Example 1 90 parts by weight of a bisphenol A type epoxy resin (Okaka Shell Epoxy Co., Ltd., Epicoat 1001) and 10 parts by weight of a polyfunctional epoxy resin (Okaka Shell Epoxy Co., Ltd., Epicoat 154) were added. 2.2 parts by weight of dicyandiamide as a curing agent, 44 parts by weight of methyl ethyl ketone and 50 parts by weight of methyl cellosolve as a solvent, and as a curing accelerator in a weight ratio of (1) :( 2) :( 3) is 4
An epoxy resin varnish was prepared by mixing 0.2 part by weight of imidazole silane (manufactured by Japan Energy Co., Ltd.), which is a mixture of 5:22:33.

Next, a glass woven fabric base material of specification 7628 type (alkali-free plain woven glass cloth for laminated plates) was impregnated with this epoxy resin varnish so that the resin content was about 50%, and dried with hot air at 110 ° C. A prepreg having a thickness of 240 μm was prepared by heating and drying with a machine for 10 minutes. Then, by stacking 8 sheets of this prepreg, a copper foil of 1 oz (thickness 35 μm) (JTC foil, manufactured by Nikko Gould Foil Co., Ltd.) was used as a metal foil, and the prepreg was stacked on one side. ^An epoxy resin-based copper clad laminate was obtained by forming a laminate for 70 minutes under the heating and pressing conditions of ² .

Example 2 An epoxy resin-based copper clad laminate was obtained in the same manner as in Example 1 except that 1.35 parts by weight of imidazole silane was mixed as a curing accelerator to prepare an epoxy resin varnish.

Example 3 As a curing accelerator, 0.2 parts by weight of imidazole silane and 0.24 parts by weight of 2-ethyl-4-methylimidazole (manufactured by Shikoku Kasei Co., Ltd., Cureazole 2E4MZ) were blended together to prepare an epoxy resin. An epoxy resin-based copper clad laminate was obtained in the same manner as in Example 1 except that the resin varnish was prepared.

Comparative Example: 0.22 parts of 2-ethyl-4-methylimidazole (manufactured by Shikoku Kasei Co., Ltd., Curezole 2E4MZ) alone as a curing accelerator was added to prepare an epoxy resin varnish. An epoxy resin-based copper clad laminate was obtained in the same manner as in Example 1.

With respect to the copper-clad laminate obtained as described above, the peel strength was measured in order to evaluate the adhesiveness in the normal state, the heat-resistant aging resistance (the adhesiveness before and after heat treatment at 180 ° C. for 2 days), Moisture resistance (adhesion before and after treatment in boiling water for 5 hours) was performed. In the moisture resistance evaluation, the treatment time was extended for the purpose of further clarifying the difference in adhesive strength. According to the UL standard, the heat aging resistance evaluation is 177 ° C. for 10 days, but the evaluation is a simplified evaluation. The results are shown in Table 1.

[0029]

[Table 1]

As can be seen from Table 1, the epoxy resin laminate obtained by using imidazole silane or a combination of imidazole silane and 2-ethyl-4-methylimidazole as a curing accelerator for epoxy resin is 2-ethyl-4-.
It is confirmed that the adhesive property is improved as compared with the comparative example using only methylimidazole.

[0031]

As described above, according to the present invention, since the resin varnish prepared by blending the epoxy resin with the specific imidazole silane as the curing accelerator is used, the copper foil of the obtained epoxy resin laminate is obtained. It is possible to improve the adhesiveness between the resin and the base resin.

Front Page Continuation (72) Inventor Masashi Kumagai 3-17-35, Shinzonan, Toda City, Saitama Prefecture Within Japan Energy Co., Ltd.

Claims (2)

[Claims] 1. A general formula (1) or (2) below as a curing accelerator:
Alternatively, a prepreg characterized in that a base material is impregnated with an epoxy resin composition containing imidazole silane represented by (3) or a mixture thereof, and is dried and semi-cured. Embedded image (However, R ¹ is hydrogen, a vinyl group or an alkyl group having 1 to 5 carbon atoms, R ² is hydrogen or an alkyl group having 1 to 20 carbon atoms, and R ³ and R ⁴ are alkyl groups having 1 to 3 carbon atoms. Group, n is 1-3) 2. A copper clad laminate, wherein copper foil is placed on one or more of the prepregs according to claim 1 and laminated and cured.