JP2716639B2 - Low dielectric constant thermosetting resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high heat-resistant thermosetting resin composition having a low dielectric constant, a low dielectric loss tangent, and excellent adhesion to metals. It is preferably used for

[0002]

2. Description of the Related Art In recent years, there has been a demand for a resin for a laminate having excellent heat resistance and a low dielectric constant and a low dielectric loss tangent for a printed wiring used in a high frequency range. On the other hand, thermoplastic resins such as fluororesins and polyphenylene ether resins having a small dielectric constant have been proposed, but have problems such as poor workability and adhesiveness and lack of reliability. Therefore, an epoxy-modified polyphenylene ether resin or a polyphenylene ether-modified epoxy resin has been proposed for the purpose of improving workability and adhesiveness. However, the dielectric constant of the epoxy resin is high and satisfactory characteristics have not been obtained. A curable resin composition obtained by blending a polyphenylene ether resin and a polyfunctional cyanate ester resin, and further mixing other resins, adding a radical polymerization initiator, and performing a preliminary reaction (Japanese Patent Application Laid-Open No. S57-18535).
No. 0) is known, but the decrease in the dielectric constant was insufficient.

A polybutadiene resin containing thermosetting 1,2-polybutadiene as a main component has a low dielectric constant.
The adhesiveness was poor and the heat resistance was insufficient. Composition containing 5 to 20 parts by weight of a 1,2-polybutadiene resin, 5 to 10 parts by weight of a crosslinkable monomer and a radical crosslinking agent per 100 parts by weight of a polyphenylene ether resin (JP-A-61-8)
However, when a 1,2-polybutadiene resin having a molecular weight of several thousand is used, stickiness remains when the solvent is removed from the composition, and the composition is coated and impregnated on a glass substrate or the like. There is a practical problem since the obtained prepreg cannot maintain a tack-free state. On the other hand, in order to eliminate stickiness, there is a method using 1,2-polybutadiene having a high molecular weight. However, according to this method, the solubility in a solvent is reduced, the solution becomes high in viscosity, and the fluidity is reduced, which is a practical problem. Was.

[0004]

SUMMARY OF THE INVENTION The present invention has been made as a result of intensive studies to obtain a thermosetting resin having low dielectric constant, high heat resistance, high adhesiveness and excellent workability. .

[0005]

That is, the present invention provides an epoxy resin containing, as a main component, an epoxy resin (A) represented by the following general formula containing two or more epoxy groups in a molecule:

[0006]

Embedded image (R represents an alkyl group of H or C ₁ -C _10, each R may be the same or different, .k least one of R is the alkyl group is an integer of 0. ) A phenol compound (B) represented by the following general formula:

[0007]

Embedded image (L and m are 0 or an integer of 1 or more, n is a natural number, and x represents H or an alkyl group.).

[0008]

The epoxy resin (A) used in the present invention
Is a novolak type epoxy resin, and thus has excellent heat resistance and adhesiveness. Also, by having two alkyl substituents on the benzene nucleus, the dielectric constant of the epoxy resin can be kept low. An epoxy compound containing only one epoxy group in the molecule is not preferable because the curability is insufficient and only a cured product having low heat resistance can be obtained. Desirable epoxy resin (A)

[0009]

Embedded image (K is an integer of 1 to 3.)

An epoxy resin having a C ₃ -C ₈ alkyl substituent having the above structure in the molecule is preferred. And

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Preferred examples include a combination of epoxy resins having a halogen substituent, and a reaction product with a phenol compound having a halogen substituent such as tetrabromobisphenol A can be preferably used. Not something. The epoxy resin of the present invention preferably has a halogen substituent equivalent to 15 to 40% by weight of the total amount. If it is less than 15% by weight, flame retardancy cannot be obtained, so that it is not preferable. If it exceeds 40% by weight, heat resistance is impaired, so that it is not preferable. The halogen substituent is not particularly limited, and examples thereof include bromine and chlorine. Further, a flame retardant aid can be added as needed. The phenol compound (B) used in the present invention is represented by the general formula (2), but has a phenolic hydroxyl group in the molecule, and thus functions as a curing agent for an epoxy resin. Furthermore, the molecular skeleton has 1,2
It has a-or 1,4-polybutadiene residue and has a cyclized structure, which is preferable because it has a function of lowering the dielectric constant and the dielectric loss tangent. The phenolic compound preferably has a hydroxyl equivalent of 350 to 2,000. If it is less than 350, the effect of improving the dielectric properties is undesirably reduced, and if it is more than 2,000, the crosslinking density of the epoxy curing agent decreases, and sufficient heat resistance cannot be obtained, which is not preferred. Although the epoxy resin composition of the present invention contains a specific epoxy resin and a phenol compound, a curing accelerator can be used to adjust the curing speed. As the curing accelerator, an imidazole compound, an organic phosphorus compound, a tertiary amine, a quaternary ammonium salt, or the like is used. Some of these accelerators can be used in combination. The compounding amount is preferably 0.01 to 5% by weight based on the epoxy resin. If it is less than 0.01% by weight, the accelerating effect is small, and if it exceeds 5% by weight, the storage stability decreases.

Although the epoxy resin composition of the present invention is used in various forms, a solvent is often used when coating and impregnating a substrate. The solvent used is required to show good solubility in part or all of the composition,
A poor solvent can be used as long as no adverse effect is exerted. Examples of solvents used include acetone, methyl ethyl ketone, methyl isobutyl ketone, ketone solvents such as cyclohexanone, aromatic hydrocarbon solvents such as toluene, xylene and mesitylene, methyl cellosolve, ethyl cellosolve butyl alsolve, and isobutyl. Cellosolve, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene ghoul monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol monopropyl ether,
Various glycol ether solvents such as ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, etc .; ester solvents such as methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, and ethyl acetate; ethylene glycol dimethyl ether; diethylene Gutacol dimethyl ether,
Dialkyl glycol ether solvents such as diethylene glycol diethyl ether and diethylene glycol dibutyl ether, N, N-dimethylacetamide, N, N
There are amide solvents such as -dimethylformamide and N-methyl-2-pyrrolidone, and alcohol solvents such as methanol and ethanol, and some of these can be used in combination.

A varnish obtained by using the epoxy resin composition of the present invention with the above-mentioned solvent is coated and impregnated on a substrate such as glass woven fabric, glass nonwoven fabric or paper, or a cloth having a component other than glass, and then impregnated in a drying oven. By drying in the range of 80 to 200 ° C., a prepreg for a printed wiring board can be obtained. Prepreg is used to manufacture printed wiring boards by heating and pressing, but the epoxy resin composition of the present invention has low dielectric constant, low dielectric loss tangent, excellent workability, excellent adhesion to metal, and high heat resistance. It is a thermosetting resin and is suitably used for a laminate, a metal-clad laminate, and the like.

[0014]

The present invention will be described in more detail with reference to the following examples. << Example 1 >> 66 parts of an epoxy compound represented by the following formula having an epoxy equivalent of 240 (parts by weight, the same applies hereinafter)

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34 parts of tetrabromobisphenol A was added thereto, and the mixture was heated and stirred at 120 ° C., and 0.01 parts of 2-methylimidazole was further added. The mixture was reacted at 150 ° C. for 4 hours.
A solid epoxy resin having an epoxy equivalent of 470 and a bromine content of 20% was obtained. Hereinafter, this is abbreviated as resin (a). A phenolic resin PP-700-300 manufactured by Nippon Oil Co., Ltd. having an OH equivalent of 317 with respect to the resin (a) (l = m = 0, n = 1.23 in the compound formula (2)) is used as the resin (a). And the equivalent ratio (moles of epoxy groups / moles of hydroxyl groups) to 1 was obtained. Further, 0.8 parts of a curing accelerator and 2-ethyl-
4-Methylimidazole was added, and the varnish solution was adjusted with methyl ethyl ketone to a non-volatile content of 55%.
Then, using this varnish, a glass cloth (thickness 0.1)
100 parts of 8 mm E glass manufactured by Nitto Boseki Co., Ltd. was impregnated with 43 parts of a varnish with a solid content and dried in a drying oven at 150 ° C. for 4 minutes to prepare a prepreg. The obtained prepreg was tack-free and excellent in workability. Eight pieces of the dried prepregs were stacked and electrolytic copper foil having a thickness of 35 μm was stacked on the upper and lower sides, and heated and pressed at a pressure of 40 kgf / cm ² and a temperature of 175 ° C. for 1 hour to obtain a 1.6 mm thick laminated plate. After the surface of the laminate was removed by etching, the pressure was set at 121 ° C. 2.
The treatment was performed for 20 hours under a pressure cooker condition of 0 atm, and the weight increase was measured. Table 2 shows the results.

The measurement of the dielectric constant and the dielectric loss tangent are based on JIS C
The measurement was performed according to 6481, and the capacitance at a frequency of 1 MHz was measured. JIS for solder heat resistance and peel strength
Measured according to C 6481. Solder heat resistance is 260 ° C, 30
At 0 seconds, the appearance was checked for abnormalities. Flame retardant is UL-94
It was evaluated by the vertical method according to the standard. The glass transition temperature was determined from the peak temperature of tan δ by the viscoelastic method. The results are shown in Table 2. << Comparative Examples 1 and 2 >> As shown in Table 1, except for the composition of each epoxy resin and the curing agent, laminated boards were prepared in the same manner as in the examples, and various characteristics were evaluated. Table 2 shows the results.

[0017]

[Table 1]

[0018]

[Table 2]

[0019]

As is clear from the results shown in Tables 1 and 2, the epoxy resin composition of the present invention has a low dielectric constant, a low dielectric loss tangent, and excellent thermosetting properties with excellent adhesion to metal and excellent heat resistance. It is a resin composition. Therefore, it is the most suitable resin for printed wiring boards that require low dielectric constant and low dielectric loss tangent, and copper-clad laminates can be manufactured in the same process as conventional resin for laminates, which is an industrial advantage. Is big.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location // H01B 3/40 H01B 3/40 K

Claims (3)

(57) [Claims] 1. An epoxy resin containing, as a main component, an epoxy resin (A) represented by the following general formula containing two or more epoxy groups in a molecule: (R represents H or an alkyl group of C _{1 to} C ₁₀ , wherein each R may be the same or different, at least one of R is the alkyl group, and k is an integer of 0 to 10. ) A phenolic compound (B) represented by the following general formula: (L and m are 0 or an integer of 1 or more, and n is a natural number.
x represents H or an alkyl group. A) a low-permittivity thermosetting resin composition comprising: 2. An epoxy resin having a total amount of 15 to 4
2. The resin composition according to claim 1, having 0% by weight of a halogen substituent. 3. The resin composition according to claim 1, wherein the phenolic compound (B) has a hydroxyl equivalent of 350 to 2,000.