JPH05315723A - Combinational board - Google Patents

Abstract

PURPOSE:To prevent plating of a through hole formed on a pad for connection of an auxiliary circuit from breaking for heightening soldering strength in a combinational board for mounting an auxiliary circuit board on a main circuit board. CONSTITUTION:A circular through hole 11 is formed so as to connect pads 5 for connection on both end surfaces of an auxiliary circuit board 3 and to make the distance between an end side internal surface and an end of a through hole 11 larger than the thickness of through hole platiang while filling the through hole 11 with solder 7 for connecting and solidifying a pad 2 for mounting and a pad 5 for connection of the main circuit board 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combination board in which a sub circuit board is electrically and mechanically connected to a main circuit board.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view of a conventional combination board disclosed in, for example, Japanese Patent Laid-Open No. 4-48680, and FIG.
-A sectional drawing and FIG. 6 are perspective views of the sub circuit board. In the figure, 1 is a main circuit board, 2 is a surface mounting pad formed on the surface of the main circuit board 1, 3 is a sub-circuit board mounted on the main circuit board 1, and 4 is a surface of the sub-circuit board 3. The formed wiring pattern, 5 is a connecting pad formed on both sides of the end portion of the sub-circuit board 3 so as to be connected to the wiring pattern 4, and 6 is the sub-circuit board 3 so that the pads 5 on both sides are connected.
A semicircular end face through hole formed at the end of the, and a welded solder 7 for connection.

The above conventional combination board is a sub-circuit board 3
Pad 5 and end surface through hole 6 are formed at the end of
It is formed by joining the pads 2 of the main circuit board 1 with solder 7.

In this combination board, cream solder is applied to the surface mounting pads 2 of the main circuit board 1, and the end surface through holes 6 of the sub circuit board 3 are mounted on the pads 2 so as to be mounted thereon. It is formed. When the cream solder is melted at this time, the inner wall surface of the end face through hole 6 is filled with the solder 7, and then the solder 7 forms a fillet-shaped curve between the pads 2 and 5.

The melted solder can be moved by the end face through holes 6, and the solder fillet is formed evenly on the left and right. Further, since the end face through hole 6 is also filled with the solder 7, the soldering strength is stronger than the soldering between pads. As described above, the main circuit board 1 and the sub circuit board 3 are electrically and mechanically connected.

[0006]

In the conventional combination board, the pad 5 and the end surface through hole 6 are formed at the end portion of the sub-circuit board 3 as described above. After forming the through hole, it is necessary to cut the through hole by external processing to make a semicircular recess, the through hole plating is easily damaged by mechanical stress, the soldering strength is reduced, and burrs occur. There was a problem such as doing.

The present invention has been made in order to solve the above problems, and it is possible to form through holes so that the through hole plating at the end portion is not destroyed by the mechanical stress at the time of processing the outer shape of the substrate. It is an object of the present invention to form a solder fillet evenly on the left and right sides to obtain a combination board capable of increasing soldering strength.

[0008]

A combination board according to the present invention includes a main circuit board having surface mounting pads, and a sub circuit board having connecting pads formed on both surfaces of an end portion.
A through hole formed so as to connect the connection pads on both surfaces of the sub circuit board, and the distance between the end side inner wall and the end portion is larger than the thickness of the through hole plating; and for surface mounting of the main circuit board. A combination board is provided which has a pad for connection of a sub-circuit board mounted on the pad and which is connected to both pads, and solder which is filled in the through hole.

[0009]

In the combination board according to the present invention, the pads for connecting the sub circuit board are mounted on the pads for mounting the surface of the main circuit board, and the pads are connected by soldering, and the through holes are filled with solder. It is fixedly formed. Since the distance between the inner wall and the end of the through hole is larger than the thickness of the through hole plating, breakage of the through hole plating in the substrate outer shape processing is prevented, and the reliability of electrical and mechanical connection of the combination board is increased.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a sectional view showing a combination board of the embodiment, FIG. 2 is a perspective view of the sub-circuit board, FIG. 3 (a) is a front view of the sub-circuit board, and FIG. 3 (b) is a state mounted on the main circuit board. 7 is a cross-sectional view showing the same, in which the same reference numerals as those in FIGS. 4 to 6 indicate the same or corresponding portions.

The main circuit board 1 is constructed similarly to the conventional one. The sub-circuit board 3 is also formed in substantially the same manner as the conventional one, but a circular through hole 11 is formed as a through hole for connecting the connection pads 5 on both sides, instead of the conventional semi-circular shape. Through-hole plating 12 is formed on the inner peripheral surface thereof. 7a is cream solder applied on the surface mounting pad 2 of the main circuit board 1.

In the above structure, the distance L between the inner wall of the end of the through hole 11 and the end of the sub-circuit board 3 is larger than the thickness Tm of the plating 12 of the through hole 11 and the thickness Ts of the cream solder 7a. Smaller than Tm <L <T
It has a relationship of s.

In the above-mentioned combination board, cream solder 7a is applied on the surface mounting pad 2 of the main circuit board 1, and the connection pad 5 of the sub circuit board 3 is mounted on the pad 2 and mounted. Formed. At this time, since the thickness Ts of the cream solder 7a is larger than the distance L between the inner wall and the end of the through hole 11, when the solder is heated to melt the solder, the solder 7 is filled in the through hole 11 and the space between the pads 2 and 5 is increased. The solder 7 forms a fillet-like curve and firmly connects them.

In this case, by setting L <Ts, the melted solder flows in the through holes 11 and solder fillets are formed evenly on the left and right. Further, the solder 7 is attached to the inner wall of the through hole 11 to increase the soldering strength. Further, by setting Tm <L, the mechanical stress at the time of external processing of the sub circuit board 3 is reduced by the through hole 1.
It is possible to prevent the plating 12 from being damaged and the soldering reliability is improved.

[0015]

As described above, according to the present invention, the distance between the end side inner wall and the end of the through hole of the sub-circuit board is made larger than the thickness of the through hole plating, and the solder is placed in the through hole. Since it is configured to be filled, mechanical stress is not applied to the through holes during external processing of the sub circuit board, damage to the through hole plating is prevented, and solder fillets are formed evenly on the left and right when combining the boards,
In addition, the soldering strength is also increased.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a combination board according to an embodiment.

FIG. 2 is a perspective view of the sub circuit board of FIG.

FIG. 3A is a front view of a sub circuit board, and FIG. 3B is a sectional view showing a state where the sub circuit board is mounted on the main circuit board.

FIG. 4 is a cross-sectional view of a conventional combination board.

5 is a cross-sectional view taken along the line AA of FIG.

6 is a perspective view of the sub-circuit board of FIG.

[Explanation of symbols]

 1 Main Circuit Board 2 Surface Mounting Pad 3 Sub Circuit Board 4 Wiring Pattern 5 Connection Pad 6, 11 Through Hole 7 Solder 7a Cream Solder 12 Through Hole Plating

Claims (1)

[Claims] 1. A main circuit board having a surface-mounting pad, a sub-circuit board having connection pads formed on both sides of an end, and a connection pad formed on both sides of the sub-circuit board. And the distance between the end side inner wall and the end is larger than the thickness of the through hole plating, and the connection pad of the sub circuit board is placed on the surface mounting pad of the main circuit board. A combination board, comprising: a solder that connects both pads and that fills the through hole.