JPH0820653A - Production of prepreg - Google Patents

Abstract

PURPOSE:To produce a prepreg by which a resin solid content is not cured in a varnish to be impregnated in a substrate. CONSTITUTION:This method for producing a prepreg comprises the first impregnation process for impregnating a resin varnish containing an epoxy resin as a component into a glass substrate and subsequently drying the impregnated resin varnish, and the second impregnation process for impregnating a curing varnish containing an epoxy resin-curing agent as a component into the primary prepreg obtained in the first impregnation process and subsequently drying the impregnated curing agent. The method for producing the prepreg also includes the first process for impregnating a curing varnish containing an epoxy resin-curing agent as a component into a glass substrate and subsequently drying the impregnated curing varnish, and the second impregnation process for impregnating a resin varnish containing an epoxy resin capable of being cured with the curing agent as a component into the primary prepreg obtained in the first impregnation process and subsequently drying the impregnated resin varnish.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a prepreg used for manufacturing a circuit board.

[0002]

2. Description of the Related Art A conventional prepreg manufacturing method involves impregnating a base material such as a glass cloth or a glass non-woven fabric with a varnish containing an epoxy resin and a curing agent that reacts with an epoxy group as a component, and then removing a solvent constituting the varnish. It was usually dried to remove.

In this conventional method, since the varnish contains an epoxy resin and a curing agent such as dicyandiamide which reacts with the epoxy resin, the reaction proceeds gradually in the varnish to form a cured epoxy resin. As a result, the viscosity of the varnish increases. As the viscosity increases, the impregnation property with respect to the base material deteriorates. If the curing reaction of the resin proceeds in the varnish in this way, it is not suitable for the production of prepreg. So-called varnishes with a short pot life have little utility in the production of prepregs.

[0004]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a prepreg manufacturing method capable of manufacturing a prepreg using a varnish in which a curing reaction of a resin solid content impregnated in a base material does not proceed. To do.

[0005]

A method for producing a prepreg according to a first aspect of the present invention is a method of impregnating a glass substrate with a resin varnish containing an epoxy resin as a component, followed by a primary impregnation step, and a primary impregnation step obtained in the primary impregnation step. The method for producing a prepreg of the invention according to claim 2 is characterized in that the prepreg includes a secondary impregnation step of impregnating and drying a curing agent varnish containing the curing agent for the epoxy resin as a component. A primary impregnation step of impregnating a glass base with a curing agent varnish, and drying, and a secondary impregnation of the primary prepreg obtained in the primary impregnation step, impregnated with a resin varnish containing an epoxy resin cured by the above curing agent When the invention of claim 1 and the invention of claim 2 are compared with an epoxy resin and a curing agent thereof, the primary impregnation step in the invention of claim 1 is characterized by including a step. The secondary impregnation step 2 of the invention, in which the secondary impregnation process corresponds to the primary impregnation step.

[0006]

[Working] In the invention according to claim 1, since the curing agent that reacts with the epoxy resin is not contained in the resin varnish impregnating the base material in the primary impregnation step, the curing reaction of the epoxy resin in the resin varnish proceeds. The epoxy resin, whose curing reaction proceeds with the curing agent, is not included in the curing agent varnish that impregnates the substrate in the secondary impregnation step, so the reaction of the curing agent in the curing agent varnish does not proceed, The reaction of the resin solids in the varnish does not proceed.

In the invention according to claim 2, since the epoxy resin which reacts with the curing agent is not contained in the curing agent varnish impregnating the base material in the primary impregnation step, the curing reaction by the curing agent in the curing agent varnish. Does not proceed and the curing agent that hardens the epoxy resin is not contained in the resin varnish that impregnates the base material in the secondary impregnation step, so the curing reaction of the epoxy resin in the resin varnish does not proceed, and The reaction of resin solids in the varnish does not proceed.

In each of the inventions, a prepreg in which a base material is impregnated with an epoxy resin and a curing agent can be obtained only through a primary impregnation step and a secondary impregnation step. Therefore, when this prepreg is hot pressed, a circuit board is manufactured. can do.

The inventions according to claims 1 and 2 will be described below in order. The invention according to claim 1 includes a primary impregnation step and a secondary impregnation step. In the primary impregnation step, the resin varnish impregnating the base material contains an epoxy resin as a component, and since this epoxy resin has a property of undergoing a curing reaction, it contains two or more epoxy groups in the molecule.
Examples of the epoxy resin include bisphenol A, bisphenol F, hydroquinone, resorcin, phloroglysin, tris (4-hydroxyphenyl) methane, 1.1.
.Phenol such as 2.2.2-tetobis (4-hydroxyphenyl) ethane or tetrabromobisphenol A
Glycidyl ether compounds derived from halogenated bisphenols such as, novolak epoxy resins derived from novolac resins which are reaction products with phenols such as phenol and O-cresol, and other known amine epoxy resins and fats A cyclic epoxy resin or the like can be applied.

As a solvent for dissolving these epoxy resins, organic compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl cellosolve, ethyl cellosolve, methylene chloride and chloroform are used.

The epoxy resin in the varnish is preferably 30 to 80% by weight, but is not limited thereto. As the base material, a glass base material that constitutes a conventional circuit board is generally used, and may be woven cloth or non-woven cloth. Of course, the glass is not limited, and pulp paper may be used.

The above-mentioned resin varnish is impregnated into the base material by immersing the base material in the resin varnish or spraying the resin varnish onto the base material. The impregnation of these can be carried out by a known conventional means. The base material impregnated with the resin varnish contains a solvent, and when immersed in the curing agent varnish in the secondary impregnation step in this state, the epoxy resin or the curing agent varnish held in the base material flows out, so that the material is dried, Fix in the substrate. The suitable drying temperature is 20 ° C to 200 ° C.

The primary prepreg on which the epoxy resin is fixed in the above steps is transferred to the secondary impregnation step and impregnated with the curing agent varnish.

The hardener varnish in the secondary impregnation step contains a hardener as a component and does not contain an epoxy resin as a component.
As the hardener, various known hardeners such as dicyandiamide (DICY), dimethylbenzylamine (DMBA), phenol compounds such as phenol novolac and cresol novolac, and other acid anhydrides can be used. Further, a known curing accelerator may be included as a component. For impregnating the primary prepreg, the secondary impregnation step is essentially the same as the primary impregnation step.

As the solvent for the curing agent varnish in the secondary impregnation step, the solvent for the resin varnish used in the primary impregnation step is used, and the curing agent is preferably 5 to 40% by weight based on the curing agent varnish. In the secondary impregnation process, the solvent in the curing agent varnish impregnated in the primary prepreg is removed by drying, and at the same time, the epoxy resin fixed in the base material in the primary impregnation step reacts with the curing agent to cause half of the B stage. A cured epoxy resin is produced, and this B-stage semi-cured epoxy resin gives a prepreg having a property that the curing reaction progresses when heated further. Dry 5
A temperature of 0 ° C to 150 ° C for 1 to 20 minutes is suitable.

The above is the description of the invention according to claim 1, but the invention according to claim 2 is a step of impregnating with a curing agent in the primary impregnation step, in comparison with the invention according to claim 1. Although there is a difference in the step of impregnating the epoxy resin in the next impregnation step, there is no difference in the other points, so that the description is omitted.

[0017]

EXAMPLES Examples and comparative examples will be given below. (Example 1) Epoxy equivalents 460 to 51 marketed by Dainippon Ink and Chemicals, Inc. as Epiclon (registered trademark)
125 parts by weight of 0 g / eq of brominated bisphenol A type epoxy resin (hereinafter simply referred to as "part") was dissolved in 30 parts of acetone to obtain a resin varnish. 210 in this resin varnish
g / m ² , thickness 0.18 mm, density 44 × 33 pieces / in
A plain weave glass cloth for ch was dipped in and impregnated and then dried at 160 ° C. for 6 minutes to remove the solvent, thereby obtaining a primary prepreg. The resin content of this primary prepreg was 43% by weight (based on the whole).

Next, this primary prepreg was transferred to the secondary impregnation step to obtain the desired prepreg. The composition of the curing agent varnish in the secondary impregnation step is DICY 4 parts, D
MBA was 0.2 part and the solvent was 40 parts of methyl cellosolve.

For the impregnation, the primary prepreg in the hardener varnish was dipped and dried. Drying was performed at 160 ° C for 1 minute. The solvent of the target prepreg was removed and there was no stickiness. The resin content was 45% by weight (based on the whole), which was an increase of 2% by weight as compared with the primary prepreg.

Eight sheets of this prepreg are stacked and the temperature is 160 ° C.
kg / cm ² Heat and pressure for 3 minutes, 160 ℃ 40kg / c
It was heated under m ² for 60 minutes to obtain a circuit board having a thickness of 1.6 mm.

The bending strength was measured as the performance resulting from the increase / decrease in the amount of cured epoxy resin of this circuit board, and was 410 N / mm ² . The resin flow is 28
% By weight. (Example 2) As a curing agent, 4 parts of DICY, DMBA0.
Two parts were dissolved in 40 parts of methyl cellosolve to obtain a hardener varnish. This curing agent varnish had 210 g / m ² and a thickness of 0.
A plain weave glass cloth of 18 mm and a density of 44 × 33 / inch was dipped and impregnated. Then, it was dried at 160 ° C. for 30 seconds and the solvent was removed to obtain a primary prepreg.
The content of the curing agent in this primary prepreg was 3% by weight.

Next, this primary prepreg was transferred to the secondary impregnation step to obtain the desired prepreg. As the epoxy resin in the secondary impregnation step, the same epoxy resin as in Example 1 was used. 125 parts by weight of this epoxy resin was dissolved in 30 parts of acetone to obtain a resin varnish. A primary prepreg was dipped in this resin varnish for impregnation and dried at 160 ° C. for 5 minutes to remove the solvent. The solvent was removed from this prepreg and there was no stickiness. The resin content was 45% by weight, which was 42% by weight higher than that of the primary prepreg.

Eight of these prepregs are stacked and the temperature is kept at 160 ° C. for 1
kg / cm ² Heat and pressure for 3 minutes, 160 ° C, 40 kg /
The substrate was heat-pressed for 60 minutes for ² minutes to obtain a circuit board having a thickness of 1.6 mm.

When the flexural strength was measured as the performance due to the increase / decrease in the amount of cured epoxy resin of this circuit board, it was 420 N / mm ² . The resin flow is 22
% By weight.

Comparative Example 1 125 parts of the same epoxy resin as in Example 1 was dissolved in 30 parts of acetone, and D was used as a curing agent.
Methyl cellosolve 30 with 4 parts of ICY and 0.2 parts of DMBA
It was melted in a part and added to form a varnish. The same glass cloth as in Example 1 was dipped in this varnish to impregnate it and then 16
The solvent was removed by drying at 0 ° C for 5 minutes to obtain a prepreg.
The resin content of this prepreg was 45% by weight (based on the whole).

Next, 8 sheets of this prepreg are stacked and 160
℃ 1kg / cm ² 3 minutes hot pressing, 160 ℃ 40k
It was heated and pressed for 60 minutes at g / cm ² to obtain a circuit board having a thickness of 1.6 mm.

When the flexural strength was measured as the performance due to the increase / decrease in the amount of cured epoxy resin of this circuit board, it was 440 N / mm ² . The resin flow is 25
% By weight.

[0028]

According to the present invention, comparing (Example 1) and (Example 2) with (Comparative Example 1), it is possible to obtain a prepreg capable of manufacturing a circuit board having a small decrease in bending strength. Since the epoxy resin and the curing agent do not coexist in the varnish impregnated in the base material, the curing reaction in the varnish does not proceed, and therefore, the varnish in which the curing reaction of the resin solid content impregnated in the base material does not proceed. It can be used to produce prepregs.

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Claims (2)

[Claims] 1. A primary agent impregnating step of impregnating a glass substrate with a resin varnish containing an epoxy resin as a component, and a primary prepreg obtained in the primary impregnating step with a curing agent varnish containing the curing agent of the epoxy resin as a component. A method for producing a prepreg, which comprises a secondary impregnation step of impregnation and drying. 2. A primary impregnation step of impregnating a glass base with a curing agent varnish containing a curing agent of an epoxy resin as a component and drying.
And a secondary impregnation step of impregnating the primary prepreg obtained in the primary impregnation step with a resin varnish containing an epoxy resin as a component which is cured by the above-mentioned curing agent and drying the prepreg.