JPH0368057B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing a paper-based phenolic resin laminate that exhibits little dimensional change during repeated heat treatments. BACKGROUND OF THE INVENTION In recent years, printed circuits have become more densely wired and the number of finer circuits has increased, and at the same time, the methods for mounting components on circuits have also changed. For example, the use of surface-mounted components (chip components) is increasing, and the bonding methods used for these components include adhesive curing or cream solder reflow methods, and there is a tendency for more high-temperature heat treatment processes to be required during component mounting than in the past. Moreover, these mounting processes are often automated, and in order to adapt to this, a high degree of dimensional accuracy is required of the laminates that are the substrates of printed circuits. Against this background, in recent years there has been a demand for laminates that undergo repeated heat treatments and exhibit small dimensional changes when left to absorb moisture. In order to cope with this, we have conventionally modified the laminate resin or used a two-stage coating method, that is,
A method of suppressing dimensional changes in the base material by first treating the paper base material with a solvent or a phenolic resin initial condensate, etc., then applying a phenol resin impregnating coating and drying the laminated material, and also incorporating an inorganic filler into the paper. Methods using paper base materials have been used. However, it has been difficult to suppress the difference in vertical and horizontal dimensional changes and the unique width of dimensional change, which are unique properties of paper base materials. Problems to be Solved by the Invention In the conventional methods, there is no change in the dimensional change behavior inherent to the paper base material. Since it does not strengthen the materials by cross-linking them, it is presumed that there is no improvement in dimensional change behavior. Therefore, by treating the paper base material and further crosslinking the hydroxyl groups of cellulose to form a strong three-dimensional structure, its dimensional change behavior can be improved. The present invention addresses this point of view and aims to provide a paper-based phenolic resin laminate with little dimensional change. Means for Solving the Problems In order to achieve the above object, the present invention provides ethyl epoxy resin represented by the following general formula [] alone or by blending it with a phenolic resin initial condensate, and then under acidic catalyst. Impregnated and coated on paper base material and dried. Then, a phenolic resin is impregnated and coated, and then dried, and the laminated material obtained by such two-stage coating is laminated and molded. General formula [] [R: _-CH2 - _CH2 -O or

[Formula] n: An integer from 1 to 8] Effect α-cellulose, which accounts for more than 95% of the paper base material,
It maintains its crystal structure due to strong intermolecular hydrogen bonds, and highly polar solvents such as water and methanol are known as effective solvents for treating paper base materials and improving the impregnation effect with resin. The epoxy resin represented by the above general formula [] can be dissolved in water or a mixed solvent of water and methanol, and can be expected to be sufficiently impregnated into the paper base material itself. In the general formula [], if n exceeds 8, the solubility in a water-methanol mixed solvent decreases, and therefore it is not preferable for treating paper base materials. The present invention modifies the paper base material itself by crosslinking the epoxy groups of the epoxy resin sufficiently impregnated into the paper base material and the hydroxyl groups in the cellulose of the paper base material, thereby suppressing dimensional changes to a small level. be. The epoxy resin represented by the general formula [] may be used alone or in combination with a conventionally used phenolic resin initial condensate. The phenolic resin initial condensate that can be used here is a phenol-formaldehyde initial condensate,
There are phenol-formaldehyde initial condensates modified with alkylphenols such as m-cresol or nonylphenol. When used together, at least the general formula []/phenolic resin initial condensate =
It is preferable that the ratio is 10/90 (solid weight ratio) or more.
When the amount of the epoxy resin represented by the general formula [] is less than 10, the crosslinking effect of the epoxy resin is less likely to appear, and the effect of suppressing dimensional changes is reduced. This resin solution needs to be acidic in order to promote the crosslinking reaction between epoxy groups and hydroxyl groups; if it is alkaline, no reaction between epoxy groups and cellulose will occur. The acid used is preferably a water-soluble organic acid. Example An example of the present invention will be described. Example 1 Epoxy resin represented by formula [] 100 g of water, 283 g of methanol, and 2 g of para-toluenesulfonic acid were mixed to prepare an undercoating resin solution for use in the first impregnation. After immersing 11 mils kraft paper in the undercoating resin solution, drying at 160°C for 10 minutes,
Impregnate with methanol solution of tung oil-modified phenolic resin, dry, adjust to desired degree of hardening, and reduce total resin amount.
A 50% laminated material was obtained. The tung oil-modified phenolic resin used here was obtained as follows. 720g of tung oil and m-cresol in a three-necked flask
Add 580g and 0.74g of para-toluenesulfonic acid.
After reacting at 80℃ for 1 hour, 500g of phenol, 450g of 86% paraform, and 35g of 25% aqueous ammonia were added.
The reaction was continued at 80°C, and when the reaction product hardened on a 160°C hot plate for 6 minutes, the reaction was stopped and concentrated, and methanol was then added to reduce the resin content to 50%.
It was prepared as follows. Eight sheets of the laminate material were stacked, a 35 μm thick copper foil was placed on one side, and this was heated and pressed to obtain a 1.6 mm thick single-sided copper-clad laminate. Example 2 100 g of the epoxy resin represented by the formula [] used in Example 1, 200 g of nonylphenol-modified phenolic resin solution, 517 g of water, 517 g of methanol, and 2 g of isopropyl phosphate were mixed in a ratio to prepare a resin solution for undercoating. . A single-sided copper-clad laminate having a thickness of 1.6 mm was obtained in the same manner as in Example 1 using the above resin solution for undercoating. The nonylphenol-modified phenol resin solution used here was obtained as follows. 220g of nonylphenol in a three-necked flask, 37
Add 60g of % formalin, 80g of 86% paraform, and 65g of trimethylamine, and after reacting at 80℃ for 2 hours,
600g of phenol and 450g of 86% paraform were added, and the reaction was continued at 80℃ until the reaction product cured on a 160℃ heating plate for 3 minutes.
It was cooled and adjusted to a resin content of 50% with methanol. Example 3 Epoxy resin represented by formula [] 100 g, water 283 g, methanol 283 g, and isopropyl phosphate 3 g were mixed to prepare an undercoat resin solution. Using this solution, a single-sided copper-clad laminate with a thickness of 1.6 mm was prepared in the same manner as in Example 1. I got it. Comparative example: 200 g of nonylphenol modified phenol resin solution used in Example 2, 233 g of water, 233 g of methanol
g to prepare an undercoating resin solution, and using this, a single-sided copper-clad laminate with a thickness of 1.6 mm was obtained in the same manner as in Example 1. Table 1 shows the characteristics of each laminate obtained above.

[Table] Effects of the invention As is clear from Table 1, according to the present invention,
It is possible to produce a laminate with small dimensional changes after heat treatment, and the difference in longitudinal and lateral dimensional changes is also small. Further, in the present invention, it is possible to improve insulation resistance and reduce water absorption due to the effect of introducing the epoxy resin, and the industrial value thereof is extremely large.

Claims (1)

[Scope of Claims] 1. In the production of phenolic resin laminates in which laminated materials obtained by impregnating and coating a paper base material in two steps and drying are laminated, general formula〔〕 [R: -CH ₂ -CH ₂ -O or [Formula] n: An integer of 1 to 8] An epoxy resin represented by the following formula or a mixture thereof with a phenol resin initial condensate is used under an acidic catalyst, and then A method for manufacturing a laminate, characterized by using a laminate material obtained by impregnation coating with a phenolic resin.