JPS6231516B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a guide mark for drilling holes in a multilayer printed wiring board.

When making through-holes or other holes in a multilayer printed wiring board that has an intermediate circuit board on which circuits have already been etched, guide holes are used to locate the circuits on the intermediate circuit board. A hole is drilled by aligning this guide hole with a positioning pin of a drilling machine. The following two methods are conceivable for providing a guide hole in a multilayer printed wiring board, which serves as a reference for the position at the time of drilling. One method is to drill guide holes 5 individually in advance in each of the single-sided copper-clad laminate 3 for the outer layer circuit, the prepreg 4, and the etched intermediate circuit board 1, as shown in FIG. When disposed between the molding plates 6, 6 during molding, a molding guide pin 7 is inserted into each guide hole 5, and pressure molding is performed. The other method is to attach circular or concentric guide marks 2 as shown in FIG. 3 to predetermined positions on the etched intermediate circuit board 1, as shown in FIG.
Then, the prepreg 4 and the single-sided copper-clad laminate 3 for outer layer circuits (or copper foil) are laminated and molded. Thereafter, the guide mark 2 of the intermediate circuit board 1 is exposed by means such as scraping the single-sided copper-clad laminate 3 and the prepreg 4 for the outer layer circuit in the portion shown in FIG. A guide hole 5 is drilled in the portion to serve as a reference for drilling in the subsequent process. In the former case, a special plate mold having guide pins is required, and it is also necessary to individually drill guide holes in the intermediate circuit board, prepreg, etc. in advance.
On the other hand, with the latter, such a dedicated plate mold does not require individual guide holes and is suitable for mass production, and the manufacturing cost can be reduced, but molding can be done by fixing it with guide pins. Therefore, the dimensional pitch between the guide marks may be misaligned. If you drill a guide hole according to this guide mark and put it on the drilling machine,
There is a risk that the positioning pin of the drilling machine and the guide hole will not match, making it impossible to insert the hole. If you forcefully insert a hole with a misaligned pitch into the hole, the hole will become misaligned and may not match the intermediate circuit. Put it away.

The present invention has been made to overcome this latter drawback, and its purpose is to create a shape that allows fine adjustment of the position of the guide hole in accordance with the pitch deviation during molding. To provide a guide mark for drilling holes in a multilayer printed wiring board.

FIG. 4 shows the shape of the guide mark 2 to be attached to the intermediate circuit board 1 according to the present invention. Figure a
is made up of several circles with different diameters whose centers are shifted in one direction according to the size of the diameter. Figure b shows the crosshairs shown in figure a to clarify the direction of deviation, and figure c shows the crosshairs with scales. In this way, a plurality of marks are provided with the drilling center shifted within an allowable range in the direction of the expected deviation, and these marks are used as the guide mark 2 for drilling. When doing so, use relatively well-pitched marks. It goes without saying that the positional deviation between the intermediate circuit and the guide hole 5 should be within an allowable range. The guide hole 5 thus created is used as a reference to align with the positioning pin and then placed on a drilling machine.

As mentioned above, in the present invention, even if misalignment occurs during laminated molding, by using relatively well-pitched guide marks among the guide marks when drilling guide holes, slight deviations can be absorbed to absorb the misalignment. Adjustments can be made, and the dimensional pitch between guide holes can be maintained accurately, so that deviations do not affect subsequent processes.Therefore, there is no need to drill guide holes individually in a dedicated plate mold, making it suitable for mass production. This method can eliminate the drawbacks of the method of manufacturing multilayer printed wiring boards, which is inexpensive.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing one manufacturing method for a multilayer printed wiring board, Figure 2 is a cross-sectional view showing another manufacturing method, and Figure 3 is a cross-sectional view showing another manufacturing method.
Figures a, b, and c are front views of the guide marks in the above, respectively, and Figures 4 a, b, and c are front views showing respective embodiments of the guide marks in the present invention, in which 1 is an intermediate circuit board, 2 indicates a guide mark.

Claims (1)

[Claims] 1. A guide mark for drilling holes in a multilayer printed wiring board, characterized in that a plurality of marks are provided on an intermediate circuit board, the center of which is shifted in the direction of expected deviation.