JPS5816729B2 - Method for forming marks for measuring dimensional behavior of prepreg - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a prepreg used in the field of printed wiring board manufacturing as an interlayer adhesive for multilayer printed wiring boards or as a substrate material, and in particular to a method for measuring the dimensional behavior of the prepreg during heat curing. The present invention relates to a method for forming marks used for.

Prepreg is made by impregnating and coating semi-cured (B stage) epoxy resin on a glass cloth woven from glass fibers and drying it at a relatively low temperature.It has excellent dimensional stability, heat resistance, moisture resistance, electrical properties, and mechanical strength. Because of its excellent adhesion to metals, it is widely used as a substrate material and interlayer adhesive for multilayer printed wiring boards that require high precision.

However, when the semi-cured resin of the prepreg is heated, it once becomes fluidized and then hardens; however, during hardening, shrinkage occurs and dimensional changes occur.

This dimensional change due to thermosetting has a large effect on dimensional accuracy such as the reference hole pitch during lamination of multilayer printed wiring boards.

Therefore, when using a prepreg, it is necessary to understand the dimensional behavior of the prepreg during heat curing in advance, and therefore, it is required to accurately measure the dimensional behavior of the prepreg at both the development stage and the practical stage.

Such dimensional behavior measurement is possible in principle by forming a plurality of reference marks at measurement points on the prepreg and measuring the inter-mark dimensions (mark pitch) before and after thermosetting.

Generally, methods for forming marks include writing or printing on the surface, forming recessed holes or notches, and gluing or filling mark pieces.

However, in the case of prepreg, the semi-cured resin becomes fluidized when heated, so the marks formed by the method described above may become misaligned due to the fluidization of the resin.
Therefore, since the reference mark pitch changes, there is a problem that accurate measurement of dimensional behavior cannot be performed.

Therefore, it is an object of the present invention to solve such problems, and specifically to provide a method for forming marks for measuring dimensional behavior on a prepreg that is not affected by fluidization of a semi-cured resin.

Hereinafter, the present invention will be described in detail based on embodiments with reference to the accompanying drawings.

The present invention generally involves forming marks on glass cloth, which is the base material of prepreg.

That is, as shown in the figure, a plurality of colored glass fibers 2 (indicated by chain lines) are woven vertically and horizontally into a glass cloth 1 woven from glass fibers, and their intersection points 3 constitute marks for measuring dimensional behavior.

In the illustrated example, four marks are formed by weaving two colored glass fibers vertically and horizontally, but the number and arrangement of colored glass fibers to be woven can be arbitrary depending on the number and arrangement of marks required. Of course you can.

If a semi-cured epoxy resin is impregnated and coated on the glass cloth 1 shown in the figure to form a prepreg, and the prepreg is heated and the vertical pitch, horizontal pitch, diagonal pitch, etc. of the marks 3 are measured before and after thermosetting, the prepreg can be obtained. The dimensional behavior during thermosetting can be measured.

Since the mark for measuring dimensional behavior according to the present invention is formed by weaving into the glass cloth that is the base material of the prepreg, it is completely unaffected by the heat fluidization of the semi-cured resin, thus enabling accurate dimensional behavior measurement. .

[Brief explanation of drawings]

The figure is a plan view of a prepreg glass cloth on which marks for measuring dimensional behavior have been formed by the method of the present invention. In the figure, 1 indicates a glass cloth, 2 indicates a colored glass fiber, and 3 indicates an intersection (mark).

Claims (1)

[Claims] 1 A method of forming marks used to measure the dimensional behavior of a prepreg made by impregnating and coating a glass cloth woven with glass fibers with a semi-cured resin during heat curing. Colored glass fibers are woven vertically and horizontally,
A method for forming a mark for measuring dimensional behavior of a prepreg, characterized in that the intersection of the colored glass fibers forms the mark for measuring dimensional behavior.