JP3253436B2 - Epoxy resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a novolak type phenol resin (hereinafter, referred to as "naphthalene ring epoxy resin").
Novolak resin) as a curing agent,
The present invention relates to an epoxy resin composition having excellent properties for a multilayer printed wiring board, such as a low coefficient of linear expansion, good heat resistance and through-hole reliability.

[0002]

2. Description of the Related Art Information processing devices such as computers are required to be smaller, faster and have a larger capacity. Higher signal transmission speeds are also required for multilayer printed wiring boards on which electronic components such as LSIs are mounted. For this reason, a laminated material used for a multilayer printed wiring board is required to have heat resistance and dimensional stability capable of high-density mounting, particularly low thermal expansion in the thickness direction. A typical printed wiring board has a laminated structure of a thermosetting resin such as a polyimide resin and an epoxy resin and a glass cloth.

At present, polyimide resin is mainly used as a multilayer material having ten or more layers, and epoxy resin is used only for eight or less layers. The reason is that the conventional bisphenol A type epoxy resin is inferior to the polyimide resin in heat resistance and dimensional stability. However, on the other hand, polyimide resin has a disadvantage that it is extremely expensive compared to epoxy resin, and it cannot be said that it is a material that can achieve both price and characteristics.

In recent years, various polyfunctional epoxy resins have been developed, and although a remarkable improvement in heat resistance has been observed, the coefficient of linear expansion in the thickness direction of the wiring board is still large, and reliability such as a temperature cycle test is high. In the test, cracks occurred in the through-hole conductive portions, and the reliability as a printed wiring board was insufficient. Therefore, an epoxy resin material having properties equivalent to that of a polyimide resin as a multilayer material has been strongly desired.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been made in view of the above circumstances. Accordingly, when applied to a material of a multilayer printed wiring board, the heat resistance and the thickness of an epoxy resin which gives excellent characteristics of through hole reliability. It is intended to improve the dimensional stability in the vertical direction.

[0006]

That is, the present invention provides: (A) an epoxy resin represented by the following chemical formula (1):

Embedded image An epoxy resin containing 20 to 60% by weight, and (B) a phenol compound represented by the following chemical formula (2)

Embedded image l and m represent 0 or an integer of 1 or more, and n represents an integer of 1 or more. Y represents H or an alkyl group. The present invention relates to an epoxy resin composition containing:

Generally, an epoxy resin is a compound having two or more epoxy resins in a molecule, and is obtained by reacting a polyphenol such as bisphenol A with epichlorohydrin, polyglycidyl ether of phenol novolak, cresol novolak. Polyglycidyl ethers, polyglycidyl ethers of polybasic acids such as phthalic acid and hexahydrophthalic acid, N-polyglycidyl derivatives of compounds having an amine amide or a heterocyclic nitrogen base, and alicyclic epoxies. In order to improve the reliability of the through hole of the multilayer printed wiring board, it is necessary to provide a cured product having as small a coefficient of linear expansion as possible in the thickness direction. Accordingly, this object can be achieved by using a naphthalene ring-containing epoxy resin as a part of the epoxy resin.

In the present invention, a cured product having good properties such as dimensional stability, heat resistance and through-hole reliability is provided by containing the epoxy resin of the above formula (1) in an amount of 20 to 60% by weight in the total epoxy resin. be able to. If it is less than 30% by weight, the effect of lowering the coefficient of thermal expansion of the naphthalene skeleton, which is rigid and has good intermolecular packing properties, cannot be sufficiently exerted. Since the material becomes brittle, it is not preferable because the drilling workability of drilling the printed wiring board is reduced.

In order to maintain the flame retardancy of the printed wiring board, the epoxy resin preferably has a halogen substituent of 10 to 30% by weight. If the amount is less than 10% by weight, the flame retarding effect cannot be sufficiently obtained, 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.

In the present invention, the epoxy resin is prepolymerized by preliminarily reacting an epoxy resin having a naphthalene skeleton, represented by the chemical formula (1), with another epoxy resin and a polyhydric phenol compound such as a bisphenol A compound.
The reaction at the time of curing is performed uniformly, and various characteristics of the cured product are improved. When tetrabromobisphenol A is used as the polyhydric phenol compound, flame retardancy can be achieved without deteriorating other properties.

The phenol compound 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, 1,2- or 1,
It has a 4-polybutadiene residue or has a cyclized structure, so that it has a function of lowering the dielectric constant and the dielectric loss tangent, which is preferable. The hydroxyl equivalent of the phenol compound is desirably 250 to 2,000. If it is less than 250, 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. Specific examples of the phenol compound used in the present invention include phenol resin PP- manufactured by Nippon Oil Co., Ltd.
700-300, PP-500-300, PP-700
-180 and the like, but are not particularly limited thereto. It is also possible to use other epoxy curing agents in combination as long as no adverse effect is exerted.

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 usually used when coating and impregnating a substrate. The solvent used must have good solubility in the composition, but a poor solvent can be used as long as it does not adversely affect the composition. The 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 a glass cloth, a glass nonwoven fabric, or a paper, and a cloth having a component other than glass.
By drying in the range described above, a prepreg for a printed wiring board can be obtained. Prepreg is used to produce a printed wiring board by heating and pressing.However, the epoxy resin composition of the present invention gives a cured product having excellent heat resistance and a small linear expansion coefficient in the thickness direction. It is possible to satisfy the through hole reliability of a high-layer printed wiring board having 10 or more layers, which was not obtained.

[0014]

The epoxy resin having a naphthalene ring is rigid and has good intermolecular packing properties as compared with a normal bisphenol A type epoxy resin or a novolak type epoxy resin. Therefore, this cured product has excellent heat resistance and low linear expansion coefficient. On the other hand, since it has a hard and brittle defect, this defect is solved by using the above-mentioned bisphenol A type epoxy resin or novolak type epoxy resin in combination, and when used for a multilayer wiring board,
Shows good properties in heat resistance, drill workability, etc.

Further, since the hydroxyl group generated by ring opening of the glycidyl ether group is glycidyl etherified,
Low moisture absorption due to hydroxyl groups and excellent water resistance. Furthermore, since the following compound of phenol represented by the chemical formula (2) is used as a curing agent, the crosslinking density after curing is moderate,
Improved moisture resistance, heat resistance, high frequency characteristics, and electrical insulation.

[0016]

The present invention will be described in more detail with reference to the following examples. << Example 1 >> The epoxy equivalent represented by the chemical formula (3) is 1
50 parts by weight of the glycidyl ether compound of 1,6-dihydroxynaphthalene which is 81 (hereinafter simply referred to as "part")

[0017]

Embedded image

To a mixture consisting of 16 parts of a cresol novolac type epoxy resin having an epoxy equivalent of 230, 34 parts of tetrabromobisphenol A was added and the mixture was heated at 120 ° C.
With stirring, and further add 2-methylimidazole to 0.0
One part was added and reacted at 150 ° C. for 4 hours to obtain a solid epoxy resin having an epoxy equivalent of 400, a naphthalene skeleton content of about 23%, and a bromine content of 20% (hereinafter, referred to as “the epoxy resin”).
This epoxy resin is abbreviated as resin (I)).

A phenolic resin PP-700-300 manufactured by Nippon Oil Co., Ltd. having a hydroxyl equivalent of 317 (compound (2)
In the above, l = m = 0, n = 2.1) was added so that the equivalent ratio (moles of epoxy groups / moles of hydroxyl groups) to the resin (I) became 1, and the total solid content of both was added. 0.5 part of a curing accelerator 2-ethyl-4-methylimidazole was added to 100 parts, and varnish was adjusted with methyl ethyl ketone so as to have a nonvolatile content of 55%. Using the varnish after that, 100 parts of a glass cloth (0.10 mm thick, WEA-116E-RB84 manufactured by Nitto Boseki Co., Ltd.) was impregnated with 52 parts of the varnish with a solid content, and then dried in a drying oven at 50 ° C. for 4 minutes. It was dried to prepare a prepreg.

Forty-eight dried prepregs and one on both surfaces
One piece of copper foil with a thickness of 8 μm is laminated, and contact pressure (1 kg / c
m ² ) at 170 ° C. for 3 minutes and then under a pressure of 40 kg / cm ² at 170 ° C. for 90 minutes to obtain a double-sided copper-clad laminate having a thickness of about 5 mm. After etching and removing the surface copper foil of the laminate, the laminate was treated at 121 ° C. under a pressure cooker at a pressure of 2.0 atm for 20 hours, and the weight increase rate was measured. The results are shown in Table 1. The coefficient of linear expansion in the thickness direction was measured by TMA (thermomechanical analysis), and the average value from 50 ° C. to 120 ° C. is shown in Table 1. Also, prepreg 3
Using one piece of copper foil with a thickness of 35 μm on both sides and both surfaces,
Laminate molding was performed at 175 ° C. for 60 minutes at 50 kg / cm ² to obtain a copper-clad laminate, which was subjected to interior circuit processing. The dielectric constant and the dielectric loss tangent of this inner circuit board at 1 MHz were measured.

Three inner circuit boards were used, and three prepregs were arranged between them to prepare a six-layer wiring board. The drilling property, solder heat resistance, copper foil peeling strength, and barrel crack resistance were evaluated using this wiring board. Table 1 shows the results.

Examples 2 and 3 and Comparative Examples 1 to 3 As shown in Table 1, an epoxy resin represented by the chemical formula (3), 1,6-dihydroxynaphthalenediglycidyl ether, cresol novolak epoxy resin And a laminated board and a six-layer wiring board were prepared in the same manner as in Example 1 except that the ratio and the type and ratio of the curing agent were changed, and the various characteristics described above were evaluated. Table 1 shows the results.

[0023]

[Table 1]

The measuring method is as follows. (1) Water absorption: pressure cooker treatment (121 ° C,
(2.0 atm, under saturated steam pressure) for 20 hours, and the weight increase rate was calculated. (2) Coefficient of linear expansion: Average coefficient of linear expansion from 50 ° C to 120 ° C. (3) Drilling workability: 10,000 holes were drilled with a 1 mmφ drill, and 100 of them were selected and the smear occurrence rate was determined to determine the drilling workability. (4) Solder heat resistance: After floating in a solder bath at 260 ° C. for 360 seconds, the appearance was examined. Those without blisters were OK, and those with blisters were NG. Pressure cooker processing is 1
The treatment was performed at 21 ° C. under a saturated steam pressure of 2.0 atm for 3 hours. (5) Copper foil peeling strength: J
It was measured according to IS C 6481. (6) Barrel crack resistance: After performing through-hole plating on a drilled six-layer wiring board, and performing 1000 cycles of cooling / heating cycles at -65 ° C for 30 minutes and 125 ° C for 30 minutes, the through-hole resistance was measured. , 1 from initial resistance
NG when 0% increase, OK when less than 10%
And

[0025]

As is apparent from the above description, the epoxy resin composition of the present invention uses a specific naphthalene ring-containing epoxy resin and uses a phenol compound having a small polarity as a curing agent. Higher frequency characteristics than conventional bisphenol A epoxy resin or a mixture of novolak type epoxy resin and this,
It also has a low coefficient of thermal expansion, and has significantly improved drill workability and barrel crack resistance.

The use of a phenolic compound-cured system as compared with a dicyandiamide-cured system can significantly reduce the hygroscopicity and is excellent in solder heat resistance after moisture absorption.
As described above, when the epoxy resin composition of the present invention is used as a material for a multilayer wiring board, heat resistance and dimensional stability in the thickness direction are good, so that high through-hole reliability can be obtained.

Continuation of the front page (56) References JP-A-6-1222753 (JP, A) JP-A-7-165886 (JP, A) JP-A-6-157712 (JP, A) JP-A-6-73160 (JP) JP-A-5-32924 (JP, A) JP-A-7-1557539 (JP, A) JP-A-6-248074 (JP, A) JP-A-6-211964 (JP, A) 6-1822 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 59/32 C08G 59/62 C08J 5/24

Claims (1)

(57) [Claims] (A) An epoxy resin represented by the following chemical formula (1): An epoxy resin containing 20 to 60% by weight, and (B) a phenol compound represented by the following chemical formula (2): l and m represent 0 or an integer of 1 or more, and n represents an integer of 1 or more. Y represents H or an alkyl group. An epoxy resin composition comprising: