JP3052855B2 - Wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board having a wiring pattern formed on both sides of a film-like dielectric by conductive members, and having a via hole for conducting the wiring pattern on the front and back surfaces.

[0002]

2. Description of the Related Art In general, a wiring board having a via hole of this type includes a wiring pattern on the front and back surfaces formed on both sides of a film-like dielectric, and a dielectric pattern at a position corresponding to the wiring pattern on the front and back surfaces. A hole for connecting a wiring pattern is formed in the body by etching or the like. Then, either the wiring pattern on the front surface or the wiring pattern on the back surface is press-fitted into the hole for connecting the wiring pattern, and the two wiring patterns are connected in the hole to form a via hole.

[0003]

However, in the above-described conventional wiring board, the holes for forming the via holes for connecting the wiring patterns are closed by the wiring patterns on the front and rear surfaces. For this reason, when the wiring board itself is subjected to a high temperature (for example, 100 ° C. or higher) step in the thermal process during the mounting operation on the wiring board, the air remaining in the wiring pattern connection hole expands,
Since the press-fitted wiring pattern is extruded from the inside of the hole, the wiring pattern on the front surface and the back surface is peeled off, and a connection failure of the via hole has occurred.

Accordingly, the present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a wiring board in which a connection failure of a via hole does not occur even after a heat treatment. .

[0005]

In order to achieve this object, a wiring board according to the present invention comprises a wiring pattern on the front surface and the back surface formed by conductive members on both surfaces of a film-like dielectric; And a wiring pattern connecting hole penetrating through the dielectric at a position where the wiring pattern on the back surface is formed, and the wiring pattern on the front surface and the back surface is connected through the hole for connecting the wiring pattern. Then, holes for venting air are drilled in at least one of the wiring patterns on the front surface and the back surface corresponding to the positions where the holes for connecting the wiring patterns are formed. Therefore, when the wiring board itself undergoes a high temperature step in the thermal process during the mounting work on the wiring board, the air remaining in the wiring pattern connection holes tends to expand, but the air vent hole formed in the wiring pattern is used for air removal. The air is released to the outside from the hole, so the expansion of the remaining air is suppressed,
Without pushing out the press-fit wiring pattern to the outside,
Therefore, the wiring pattern on the front surface and the back surface does not peel off.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B show a wiring board according to the present invention, wherein FIG. 1A is a plan view and FIG. 1B is a sectional view. In FIG. 1, reference numeral 1 denotes a film-shaped dielectric, on the front and back of which a wiring pattern 2 on the front surface and a wiring pattern 3 on the back surface made of a conductive member are formed. . Holes 4 for connecting wiring patterns are formed in the dielectric 1 at positions corresponding to the wiring patterns 2 and 3 on the front and back surfaces. The wiring pattern 3 on the back surface is press-fitted into the hole 4, and the wiring pattern 3 on the back surface is connected to the wiring pattern 2 on the front surface in the hole 4, and electrical conduction is performed to form a via hole.

[0007] Two air vent holes 5 penetrating through the wiring pattern 2 and communicating with the holes 4 are formed in portions corresponding to the holes 4 of the wiring pattern 2 on the front surface. In the wiring board having such a configuration, when the wiring board itself is subjected to a high temperature step in the thermal process during the mounting operation, the air remaining in the wiring pattern connection hole 4 tends to expand.
Air is released to the outside from an air vent hole 5 formed in the wiring pattern 2 on the front surface. Therefore, the wiring pattern 3 on the back surface press-fitted by the air remaining in the hole 4 does not depress, and the wiring pattern 3 on the back surface does not peel off from the wiring pattern 2 on the front surface. Connection failure is prevented. By using such a structure, it was confirmed by an experiment that a via hole, which had been peeled off in a heat step of about 100 ° C., has a heat resistance of 300 ° C. or more.

FIG. 2 shows a second embodiment of the present invention.
(A) is a sectional view, and (b) is a bottom view. In the second embodiment, in addition to the air vent holes 5 of the above-described first embodiment, a hole corresponding to the hole 4 of the wiring pattern 3 on the rear surface is formed in the hole 4 through the wiring pattern 3. Communicate 2
Each air vent hole 6 is formed. In the second embodiment, the air remaining in the hole 4 is discharged to the outside through the air vent hole 5 of the wiring pattern 2 on the front surface and the air vent hole 6 of the wiring pattern 3 on the rear surface. In addition, these first
In the second embodiment, the number of air vent holes 5 and 6 is not limited to two, but may be one.
It may be more than one.

[0009]

According to the present invention as described above, according to the present invention, corresponding to the holes of the wiring pattern connected is formed position, the front and back surfaces of the holes for at least vent one or the other to the wiring pattern perforations As a result, air remaining in the wiring pattern connection holes is discharged to the outside through the air release holes of the wiring patterns on the front and back surfaces, so that even after the heating step, the front and rear surfaces in the wiring pattern connection holes are removed. Therefore, the occurrence of a connection failure can be prevented.

[Brief description of the drawings]

FIG. 1 shows a main part of a wiring board according to the present invention, and FIG.
Is a plan view, and (b) is a sectional view.

FIGS. 2A and 2B show a main part of a wiring board according to a second embodiment of the present invention, wherein FIG. 2A is a cross-sectional view and FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Dielectric, 2 ... Front surface wiring pattern, 3 ... Back surface wiring pattern, 4 ... Wiring connection hole, 5, 6 ... Air vent hole
(Hole for venting).

Claims (1)

(57) [Claims] 1. A wiring pattern on a front surface and a back surface formed by a conductive member on both surfaces of a film-like base material, and a wiring pattern connecting through the base material at a position where the wiring pattern on the front surface and the back surface is formed. A wiring board connected to the wiring patterns on the front surface and the back surface through the holes for connecting the wiring patterns, wherein the front surface and the holes correspond to the positions where the holes for connecting the wiring patterns are formed. A wiring board, characterized in that at least one of the wiring patterns on the back surface is provided with holes for air release.