JPS5815297A - 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 The present invention relates to printed wiring boards that are soldered to each other at their terminal portions, and an object of the present invention is to increase the bonding strength without causing short circuits between terminal electrodes.

First, FIGS. 1 to 3 will explain a conventional example. Figures 1 and 2 show printed wiring boards 1 and 2 to be joined to each other.
In the plan view, 3 and 4 are wiring foils, respectively. 5.6
are respective terminal portions, in which a plurality of foils 7.8 having a width wider than the foils 3 and 4 described above are configured as a terminal electrode array. Each of these terminal electrodes has a width of a, and the distance between them is a>b in Figure bC.

Note that 9 is a reference hole for alignment.

The terminal portions 6, 6 are aligned to face each other based on the reference hole 9, and the terminal electrodes 7, 8 are bonded by thermocompression bonding with solder interposed. Its cross section is shown in FIG. 3 (7), and an enlarged view of the main part is shown in FIG. 3 (A). If we do thermocompression bonding now, the molten solder 10 will receive force in the directions of arrows F1 and F2 and try to spread, so if the terminal electrode spacing is small, the solder 10 will touch and stick to the adjacent terminal electrode, which will cause a short circuit. occurs.

Here, the width of the entire terminal electrode array is preferably smaller in order to improve packaging density. Therefore, if an attempt is made to widen the terminal electrode spacing within the limited electrode array width in view of the short circuit problem described above, the terminal polarization width a becomes smaller and the mutual bonding strength becomes weaker. There was a drawback that wire breakage occurred.

The present invention solves the above-mentioned conventional drawbacks, and provides a printed wiring board that prevents short circuits without reducing bonding strength.

An embodiment of the invention is illustrated in FIGS. 4 to 6 in plan view of a printed wiring board 11.12, each provided with a plurality of wiring foils 13.14.

Reference numeral 16.16 denotes a terminal portion, and a plurality of terminal electrode rows are formed on the upper surface of this terminal portion. In this terminal electrode row, the terminal electrodes t7a, t7b, taa, and 1ab at both ends have a large width C, and the A electrodes 19 and 20 inside these have a width e, and the electrode spacing between them is d or f. There is. Here, the electrode spacing of this embodiment is wider than that of the conventional one, that is, d>
b, d>f. Note that 21 is a reference hole for positioning.

In the above configuration, the width e of the inner terminal electrodes 19 and 20 is smaller than the electrode width C of the conventional example. Therefore, the terminal parts 15 and 16 of the above embodiment are aligned to face each other based on the reference hole 21, and the terminal electrodes 17a and 1sa, 17b and tab, and 19 and 20 are bonded by thermocompression with solder interposed. When bonded, as shown in the cross-sectional view of FIG. 6, since the electrode spacing is wide, the solder 22 does not cause prisms on adjacent electrodes, and short circuits can be prevented. −
However, the terminal electrodes 17a, 17b, 18a at both ends
.

Since the width of 18b is sufficiently wide, it is possible to maintain sufficient strength after bonding. In other words, it is possible to prevent short circuits due to solder after bonding and maintain bonding strength without changing the overall width of the terminal electrode array. 0 As is clear from the above embodiments, according to the present invention, the width of both outermost terminal electrodes is set as a dog, and the width of the other terminal electrodes is set as a dog in the terminal portions of the boards that are bonded to each other by soldering. By providing a printed wiring terminal electrode row with a small inner terminal electrode width, there is no short circuit between the terminal electrodes due to solder when they are bonded, and at the same time, it has sufficient strength after bonding. This makes it possible to provide a printed wiring board with excellent features such as the ability to

[Brief explanation of the drawing]

Figures 1 and 2 are top views of the main parts of a conventional printed wiring board;
Figure (7) is a cross-sectional view of the joint, @) is an enlarged cross-sectional view,
4 and 6 are top views of essential parts showing one embodiment of the present invention,
Figure 6 is a cross-sectional view of the joint part.
Foil, 16, 16 ・=-・One terminal part, 17a, j7b
, 18a. 18b...Terminal electrodes at both ends, 19.20...
...Terminal electrode, 22...Solder. Name of agent: Patent attorney Toshio Nakao and 1 other person 1st
Figure 4 403

Claims (1)

[Claims] A plurality of terminal electrodes are provided on the terminal portions of the respective substrates that are to be connected to each other by solder, and among the plurality of terminal electrodes, both the outermost terminal electrodes are made wide, and the width of the other inner terminal electrodes is made large. A printed wiring board characterized by its small width.