JPS6248099A - Multilayer printed circuit board - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] The multilayer printed board of the present invention is configured such that the formation rate of patterns formed in the area outside the product and the formation rate of the patterns in the product area are approximately the same. There is.

For this reason, the pressing force when laminating multilayer printed boards is applied evenly to the entire surface of the board, thereby avoiding the occurrence of void defects and sheet cutting phenomena.

[Industrial application field]

The present invention relates to an improvement in a method for manufacturing a multilayer printed board, and particularly to a multilayer printed board in which defects such as void defects are reduced by equalizing the pressure distribution during lamination.

[Conventional technology]

As shown in the configuration diagram of FIG. 2, the intermediate N board 3 constituting the multilayer printed board has a product area 1 and a non-product area 2 that plays an auxiliary role to improve the manufacturing quality of the product area 1. (The area 2 outside the product will be removed in the subsequent process).

The outside area 2 of the product is provided on the outer periphery of the product area 1.
This area is also used to prevent the end faces of the multilayer printed boards from "darling" due to the pressure applied when the multilayer printed boards are stacked. Therefore, in the area 2 outside the product, a third front pattern 8 and a third back pattern 9 are provided in order to resist the pressing force during lamination.
It is formed as shown in the figure.

The structure of a conventional multilayer printed board will be explained below with reference to FIG.

As illustrated in the figure, the conventional multilayer printed board has a signal layer pattern 6 and a power/ground layer pattern 7 on the product area 1 side, and a front pattern 8 and a back pattern on the outside product area 2 side of the outer periphery. It is composed of an intermediate layer substrate 3 having a pattern 9, and an adhesive sheet 5 (commonly known as prepreg) disposed between the three intermediate layer substrates and the substrate 3 and the surface copper foil 4 to bond them together. There is.

Thereafter, each of the above-mentioned members positioned at a predetermined position is pressed from the direction of arrow A-A' by the molding jig 10 and heated, so that the adhesive material impregnated in the adhesive sheet 5 is applied to each of these members. The parts are joined to complete a multilayer printed board.

[Problem that the invention seeks to solve]

However, in the case of the conventional multilayer printed circuit boards shown in Figures 2 and 3, the pattern of area 2 outside the product is formed regardless of the pattern of area 1, and each pattern of area 2 outside the product is It was common knowledge to use the same pattern throughout the layers.

Therefore, since the same pattern exists in the same part throughout the entire layer in the outside product area 2, the thickness of that part naturally increases. For this reason, the pressure during lamination concentrates there, creating a large unpressure difference between the parts and the parts without patterns.

This pressure difference is a major factor in the void defect 11 that entrains air between the eyebrows and the sheet cutting phenomenon 12 in which the adhesive sheet 5 is damaged due to stress concentration, and also impairs the cushioning properties of the adhesive sheet 5 (the adhesive sheet 5 is made of felt, for example). Although it has cushioning properties because it is made of paper or the like as a base material, it cannot cope with particularly large irregularities).

The present invention has been made in view of the above points, and its purpose is to provide a multilayer printed board that solves the above problems by equalizing the pressure distribution between the product area 1 and the outside product area 2 during lamination. It is on offer.

[Means for solving problems]

As shown in FIG. 1 of the embodiment drawings, the present invention is such that the pattern formation rate of the front pattern 8 in the two areas outside the product is set to be approximately equal to the pattern formation rate of the signal layer pattern 6 on the product area 1 side, and Similarly, the pattern formation rate of pattern 9 is
The pattern formation rate is set to be approximately the same as the pattern formation rate of the ground layer pattern 7.

[Effect]

In this structure, the pressing force acting on the intermediate layer substrate 3 and the adhesive sheet 5 during lamination is approximately equal in the product area 1 and the non-product area 2, so that void defects 11, sheet cutting phenomena 12, etc. obstacles can be avoided.

〔Example〕

The present invention will be described in detail below based on embodiments shown in the drawings.

FIG. 1 is a side sectional view of a main part showing an embodiment of the present invention.

Note that the same reference numerals refer to the same items throughout the plan.

As shown in FIG. 1, the multilayer printed board of the present invention has a pattern formation rate of the front pattern 8 in two examples of areas outside the product of the intermediate layer board 3 (pattern formation rate means that the area of the pattern formation part is the total area of the area The pattern formation rate of the back pattern 9 is set to be approximately the same as the pattern formation rate of the signal layer pattern 6 on the product area 1 side. are set approximately equal. Note that 16 is a signal layer blank area, 17 is a power/ground layer blank area, 1st is a front blank area, and 19 is a back blank area.

Therefore, the pressure distribution during lamination of multilayer printed boards is equalized between the product area 1 side and the non-product area 2 side, and void defects 11 and sheet cutting phenomena 12 as described in the conventional example can be prevented.
occurrence is effectively suppressed.

Note that the above means is carried out for each layer of each intermediate layer substrate 3, that is, 38 signal layers 3a and 38 power supply layers 3b, and so on.

Further, in this embodiment, table pattern 8. Although the back pattern 9 is made to correspond to the signal layer pattern 6 and the power/ground layer pattern 7 and have the same shape, the pattern formation rate is not limited to this as long as the pattern formation rate is substantially the same.

〔Effect of the invention〕

As explained above, the present invention has a great effect in that the occurrence of void defects and sheet cutting phenomena can be accurately avoided by equalizing the pressure distribution during the lamination process of multilayer printed boards.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of the main part showing an embodiment of the present invention, Fig. 2 is a plan view showing the structure of the intermediate layer board, and Fig. 3 is a side sectional view of the main part showing the structure of a conventional multilayer printed board. It is. In the figure, 1 is the product area, 2 is the area outside the product, 3 is the intermediate layer board, 3a is the signal layer, 3b is the power supply layer, 4 is the surface copper foil, 5
1 is an adhesive sheet, 6 is a signal layer pattern, 7 is a power/ground layer pattern, 8 is a front pattern, 9 is a back pattern, 10 is a molding jig, 11 is a void defect, 12 is a sheet cutting phenomenon, 1
6 is a signal layer blank area, 17 is a power/ground layer blank area, 18 is a front blank area, and 19 is a back blank area.

Claims (1)

[Claims] In the pattern configuration of an intermediate layer substrate (3) laminated on a multilayer printed board, the intermediate layer substrate (3) has a product area field and an outside product area (2). A multilayer printed board characterized in that the formation rate of the pattern formed in area (2) is set to be approximately equal to the pattern formation rate of the corresponding product area (1).