JPH05267847A - Multilayer printed circuit board - Google Patents

Abstract

PURPOSE:To eliminate peeling of a pad on a non-penetrating through hole by forming a diameter of the hole at the side of an outer layer surface smaller than that at the side of an inner surface in a multilayer printed circuit board having the hole in the pad. CONSTITUTION:A non-penetrating through hole 3 in a conical pad in which a diameter of a multilayer surface is formed smaller than that of an inner surface is provided under a pad 2 of a multilayer printed circuit board 1. Resin is filled in the hole 3 in the pad, and the pad 2 on a surface of a flat copper- plated layer 5 formed with the layer 5 is formed on the surface. Thus, since the diameter of the hole 3 at the outer layer surface in the pad is reduced to decrease the surface of the resinous copper-plated layer 5 filled at the time of laminating, a ratio of a copper foil area on the board is increased, and an adhesive strength of the entire pad 2 can be resultantly improved. Thus, the copper-plated layer of the pad is not peeled.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a multilayer printed wiring board,
In particular, it relates to a multilayer printed wiring board having a non-through hole in a pad.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a multilayer printed wiring board having a non-penetrating through hole in a pad has a cylindrical pad inside the component mounting pad 2 perpendicular to the surface of the pad 2. After the non-penetrating through holes 23 are provided and the non-penetrating through holes 23 in the pad are filled with resin at the time of stacking,
The copper plating layer 5 is formed on the surface, and the pad 23 on the surface of the flat copper plating layer 5 is formed.

[0003]

A conventional multilayer printed wiring board having a non-penetrating through hole in a pad has a bonding strength between the resin and the copper plating layer in the non-penetrating through hole under the pad filled with resin at the time of lamination. There is a characteristic that it is weaker than the adhesive strength between the surrounding base material and the copper foil, and when the mounting parts become smaller and the pad becomes smaller accordingly, the area ratio of the non-through through holes in the pad increases and the adhesive strength of the entire pad becomes weaker. Therefore, there is a problem that the pad is easily peeled off due to thermal stress when mounting the component.

It is an object of the present invention to provide a multilayer printing plate in which the pads on the non-penetrating through holes are not peeled off.

[0005]

According to the present invention, in a multilayer printed wiring board having a non-penetrating through hole in a pad, the diameter of the non-penetrating through hole on the outer layer side is smaller than the diameter on the interior side. .

[0006]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a sectional view of the essential portions of the first embodiment of the present invention.

In the first embodiment, as shown in FIG. 1, a non-penetrating through in a conical pad having a diameter of an outer layer surface smaller than a diameter of an inner layer surface under a pad 2 of a multilayer printed wiring board 1. The holes 3 are provided, the non-penetrating through holes 3 in the pads are filled with resin, and the pads 2 on the surface of the flat copper plating layer 5 on which the copper plating layer 5 is formed are formed.

As described above, since the diameter of the outer layer surface of the non-penetrating through hole 3 in the pad is reduced to reduce the area of the copper plating layer 5 on the resin filled during lamination, the copper on the base material is reduced. The ratio of the foil area is increased, and as a result, the adhesive strength of the entire pad 2 can be improved.

FIG. 2 is a sectional view of the essential portions of the second embodiment of the present invention.

In the second embodiment, as shown in FIG. 2, the non-penetrating through hole 3 in the pad is formed into a bell shape, and the drill is completely penetrated when the non-penetrating through hole is drilled. The diameter of the outer layer surface under the pad 2 can be formed smaller than the diameter of the inner layer surface by controlling the hole depth direction without performing the above operation, and the same effect as that of the first embodiment can be obtained.

In the second embodiment, a 0.5 mm pitch QF is used.
Under the pad of 0.3mm width which mounts P parts, the diameter is 0.
A 3 mm drill can be used to provide the non-penetrating through holes 13 in the pad with a diameter of 0.3 mm on the inner surface side and a diameter of 0.15 mm on the outer surface side.

[0013]

As described above, according to the present invention, the diameter of the outer layer surface of the non-penetrating through hole in the pad is made smaller than the diameter of the inner layer surface so that the copper plating layer on the non-penetrating through hole in the pad is formed. Area and the ratio of the copper foil area on the base material were increased, and as a result, the adhesive strength of the entire pad was increased, so the copper plating layer of the pad part peeled off against the thermal stress during component mounting. It has the effect of disappearing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential parts of a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of essential parts of an example of a conventional multilayer printed wiring board.

[Explanation of symbols]

 1 Multilayer printed wiring board 2 Pads 3, 13, 23 Non-penetrating through holes in pads 4 Through through holes 5 Copper plating layer

Claims (1)

[Claims] 1. A multilayer printed wiring board having a non-penetrating through hole in a pad, wherein a diameter of the non-penetrating through hole on an outer layer side is smaller than a diameter on an interior surface side. Board.