JPH0439006A - Manufacture of prepreg for laminated sheet - Google Patents

Abstract

PURPOSE:To obtain prepreg for a laminated sheet, which fas favorable coating and infiltrating properties, few bubbles and easy moldability, by a method wherein a depth of infiltration or immersion of resin varnish is made less than a thickness of a sheetlike base as the primary infiltration and a time up to the secondary infiltration from after the primary infiltration is specified. CONSTITUTION:One side infiltration is adopted ordinarily as the primary infiltrating method and varnish is infiltrated or immersed into a base up to the middle of a thickness direction of the base. When the secondary infiltration is performed after the lapse of at least 5 seconds after completion of the primary infiltration, preferably after the lapse of at least 10 seconds, meanwhile resin varnish is infiltrated into up to details, a part where the resin varnish is not infiltrated is in existence by inclining toward one side of the base and at the time of the secondary infiltration deaeration of remaining air becomes easy. With this construction, prepreg having favorable infiltration properties through which a laminated sheet where generation of ply separation and measling etc. are few in a heat treatment process such as a solder reflow after moisture absorption treatment and it is superior in electric properties also can be obtained can be manufactured.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention reduces the occurrence of delamination, measling, etc. in heat treatment processes such as soldering flow after moisture absorption treatment, and
The present invention also relates to a method for producing a prepreg with good impregnation properties, which allows a laminate with excellent electrical properties to be obtained.

[Conventional technology]

Conventionally, methods for producing prepreg for laminates with good impregnation include vacuum impregnation and multiple impregnations.To give an example of two-stage impregnation, there are two methods: ■ A method of using a low-concentration resin varnish for the primary impregnation; A method of using a face with a low viscosity resin formulation for primary impregnation, ■ A method of pre-impregnation with an organic solvent that can easily replace the resin varnish, ■ A method of degassing by applying pressure to the base material after impregnation, ■ One-sided impregnation as primary impregnation. ■Methods such as increasing the impregnation time, etc. have been considered and some have been implemented. Although each method had some effect, it was not sufficient.

[Problem to be solved by the invention]

An object of the present invention is to provide a brev leg for a laminate that has excellent electrical properties and heat resistance after moisture absorption of the laminate without reducing the productivity of the coating process.

[Means to solve the problem]

The present invention provides a method for manufacturing a prepreg for a laminate with good impregnability, and the gist thereof is: - In a method for manufacturing a prepreg by a multi-stage impregnation method, impregnation or dipping into a resin varnish is performed as metal deposition. A method for manufacturing a prepreg for a laminate, characterized in that the depth is less than the impregnation thickness of a sheet-like base material, and the time from metal deposition to secondary impregnation is 5 seconds or more. The primary impregnation method used in the present invention usually employs one-sided impregnation, and examples include (1) a kiss roll method, (2) a roll coater method,
■ One-side spray method and ■ Extremely shallow vat method. These methods are used alone or in combination to impregnate the base material with varnish. This section can be secured as a degassing path during secondary impregnation.

When primary impregnation is performed by dipping resin varnish to a depth equal to or greater than the thickness of the base material, the resin varnish suppresses defoaming of air within the base material, making defoaming during secondary impregnation difficult.

The secondary impregnation may be carried out by a conventional method, that is, immersion in an impregnating bath. However, since gold-forming immersion is usually one-sided impregnation, it is preferable to immerse the substrate with one side impregnated facing downward.

The secondary impregnation is performed at least 5 seconds, preferably at least 10 seconds after the completion of the primary impregnation. During this time, the resin varnish penetrates into the details of the base material, and the areas where the resin varnish does not penetrate exist on one side of the base material, making it easier to defoam the remaining air during the secondary impregnation.

The resin varnish used for -metal impregnation may be the same as that for the secondary impregnation, or may be different. Further, it is preferable that the resin content is the same for both or lower for the primary impregnation.

〔Example〕

The present invention will be explained below with reference to Examples and Comparative Examples.

A glass cloth (basis weight 210 g/rf) with a thickness of 200 μm was used as a sheet-like base material, and an epoxy resin varnish with a resin content of 50% was applied, impregnated (-metal immersion), and then subjected to secondary impregnation and dried.

The primary impregnation was carried out using a kiss roll (except for Comparative Example 3), and the secondary impregnation was carried out by immersion in a normal impregnating bath.

Table 1 shows: - The ratio of the depth of resin varnish impregnation to the thickness of the glass cloth base material during the metal deposition, - The time from the metal deposition to the secondary impregnation, the outside IN (visual observation) of the obtained prepreg, and this prepreg. Indicates the quality of the appearance of the laminated board formed by lamination.

The laminate was made by laminating 8 sheets of each prepreg and copper foil on both sides, and laminated and molded at 170° C. and 20 kg/cd for 90 minutes. The quality of the appearance was determined by visually inspecting the surface condition after removing the copper foil by etching.

〔Effect of the invention〕

According to the method of the present invention, there is no need to add large-scale equipment to conventional equipment, and the coating and impregnating properties are good, there are few bubbles, and
A prepreg for laminates that is easily moldable can be obtained.

A laminate plate formed by lamination using this prepreg has a good appearance and excellent properties.

Claims (1)

[Claims] (1) In the prepreg manufacturing method using the multi-stage impregnation method, as the primary impregnation, the depth of the impregnation or immersion into the resin varnish is less than the thickness of the impregnation of the sheet-like base material, and the time from the primary impregnation to the secondary impregnation is A method for producing a prepreg for a laminate, characterized in that the manufacturing time is 5 seconds or more.