JPH0738223A - Printed board - Google Patents

Abstract

(57) [Abstract] [Purpose] The weight of the electronic components to be mounted and the expansion and contraction of the adhesive resin for fixing the electronic components due to the heat cycle cause the stress applied to the electronic components, etc. Be sure to solder it so that there is no continuity failure. [Structure] An insulating plate 3, a wiring 8 provided on one surface of the insulating plate 3, and a connecting wire 5 of an electronic component 1 connected to the wiring 8 and mounted on the other surface of the insulating plate 3. A first connecting land 6A having a through hole 7 and soldering an intermediate portion of the connecting wire 5 drawn out through the through hole 7, and a first connecting land 6A connected to the first connecting land 6A. 6A
The second connecting land 6B is formed by soldering the tip of the connecting wire 5 drawn out through the through hole 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board on which electronic parts are mounted.

[0002]

2. Description of the Related Art FIGS. 2A and 2B show an example of a conventional printed circuit board. FIG. 2A is a sectional view of an essential part, and FIG. 2B is a bottom view of FIG. In FIG. 2, the printed circuit board is provided with an insulating plate 3, a wiring 8 formed on one surface of the insulating plate 3 in FIG. 2 by a printing method, and the like.
The electronic component mounted on the other surface of the
(Shown by 1 in FIG. 1) has a through hole 7 for the connecting wire 5, and the tip of the connecting wire 5 drawn out through the through hole 7 is composed of a connecting land 6 to be soldered.

In order to mount the electronic component 1 on the printed circuit board, first, the connecting wire 5 of the electronic component 1 is inserted through the through hole 7 of the connecting land 6 so that its tip end is exposed on the surface of the connecting land 6. To do. Then, the connection land 6 and the connection line 5 are connected by the solder 4. Reference numeral 2 denotes an adhesive resin, such as a hot-melt adhesive, for fixing the electronic component 1 and the insulating plate 3 to each other. Used as needed when large.

[0004]

In the above-mentioned printed circuit board, since the weight of the electronic component to be mounted is applied between the connecting wire and the connecting land of this electronic component, the solder connecting between them is cracked. Alternatively, poor continuity may occur. Further, when the electronic component and the insulating plate are fixed with an adhesive resin, stress may be applied to the electronic component due to expansion and contraction of the adhesive resin due to heat cycle, and thus cracks or conduction defects may similarly occur in the solder. .

An object of the present invention is to connect a connecting line of an electronic component to a printed circuit board due to the weight of the electronic component to be mounted or the stress applied to the electronic component due to expansion and contraction of the adhesive resin for fixing the electronic component due to heat cycle. The purpose of this is to prevent solder from cracking or poor continuity between the connection land and the solder and to ensure reliable soldering.

[0006]

In order to achieve the above-mentioned object, a printed circuit board according to the present invention comprises an insulating plate, a wiring provided on one surface of the insulating plate, and an insulating plate connected to the insulating plate. A first connection land having a through hole for a connection wire of an electronic component mounted on the other surface, and soldering an intermediate portion of the connection wire drawn out through the through hole, and the first connection land to the first connection land. The second connecting land is soldered to the tip of the connecting wire which is connected and pulled out through the through hole of the first connecting land.

[0007]

In the printed circuit board of the present invention, the connection line of the electronic component is led out to the second connection land through the through hole of the first connection land, and the connection line is the first connection land and the middle portion thereof is Since the tip of each of the two connection lands is soldered, the stress applied to the electronic component due to the weight of the electronic component or the expansion and contraction of the adhesive resin for fixing the electronic component due to the heat cycle is mainly caused by the connection line of the electronic component. It is absorbed by the portion of the solder connecting the intermediate portion and the first connecting land, and almost the stress is applied to the portion of the solder connecting the tip portion of this connecting wire and the second connecting land. Since the solder is not present, the solder is reliably soldered without causing cracks or defective conduction.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a printed circuit board according to the present invention. (A) is a sectional view of an essential part and (b) is a bottom view of (a). The printed circuit board of the present invention shown in FIG. 1 is different from the conventional printed circuit board shown in FIG. 2 in the structure of the connection lands. In FIG. In FIG. 1, there is a through hole 7 for a connecting wire 5 of an electronic component (indicated by 1 in FIG. 1) mounted on the upper surface, and an intermediate portion of the connecting wire 5 drawn out through this through hole 7 is soldered. One connection land 6A and a second connection land 6B which is connected to the first connection land 6A and solders the tip portion of the connection line 5 drawn out through the through hole 7 of the first connection land 6A. It consists of and.

To mount the electronic component 1 on this printed circuit board, first, the connecting wire 5 of the electronic component 1 is connected to the first connecting land 6.
It is inserted into the through hole 7 of A, and its tip is pulled out to the second connection land 6B. Then, the intermediate portion of the connecting wire 5 and the first connecting land 6A are connected with the solder 4A, and the tip portion of the connecting wire 5 and the second connecting land 6B are connected with the solder 4B. The adhesive resin 2 for fixing the electronic component 1 is also used as needed. In this printed circuit board, the weight of the electronic component 1 to be mounted or the stress applied to the electronic component 1 due to the expansion and contraction of the adhesive resin for fixing the electronic component due to the heat cycle is mainly caused by the intermediate portion of the connecting line 5 of the electronic component 1 and the Solder 4 connecting between 1 and the connection land 6A
The solder 4B is absorbed in the portion A, and almost no stress is applied to the portion of the solder 4B that connects the tip portion of the connection wire 5 and the second connection land 6B. It does not occur and is securely connected.

There may be a case where cracks or defective conduction occur in the portion of the solder 4A that connects the intermediate portion of the connecting wire 5 and the first connecting land 6A. The stress applied to the wire 5 is this solder 4
Since it is sufficiently absorbed in the portion B, the stress is scarcely applied to the portion of the solder 4B connecting the tip portion of the connecting wire 5 and the second connecting land 6B.

Table 1 shows the results of a heat cycle test for mounting electronic parts on the printed circuit board of the present invention and the conventional printed circuit board. For the electronic parts fixed with an adhesive resin, + 80 ° C. and -25 ° C. respectively for 45 minutes. 2 each
In a heat cycle test that repeats 00 cycles,
In the conventional printed circuit board, a small crack was partially generated in the solder after the 48-cycle test, and a large crack was generated after the 98-cycle test, and no continuity was obtained. However, the printed circuit board of the present invention was completely abnormal even after the 200-cycle test. Was not seen.

[0012]

[Table 1]

[0013]

In the printed circuit board of the present invention, the weight of the electronic component to be mounted or the expansion and contraction of the adhesive resin for fixing the electronic component due to the heat cycle causes a stress to be applied to the electronic component, which causes a connection wire between the electronic component and the connecting wire. The solder connecting the connection lands is not cracked or defective in conduction, and the reliability of the circuit is significantly improved.

[Brief description of drawings]

FIG. 1 shows an embodiment of a printed circuit board of the present invention,
(A) is a sectional view of an essential part, (b) is a bottom view of (a)

2A and 2B show an example of a conventional printed circuit board, FIG. 2A is a sectional view of a main part, and FIG. 2B is a bottom view of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electronic component (mounted) 3 Insulating plate 4A Solder 4B Solder 5 Connection line (of electronic component 1) 6A First connection land 6B Second connection land 7 Through hole 8 Wiring

Claims (1)

[Claims] 1. An insulating plate, a wiring provided on one surface of the insulating plate, and a through hole for a connecting wire of an electronic component connected to the wiring and mounted on the other surface of the insulating plate. A first connection land for soldering an intermediate portion of the connection wire drawn out through the through hole, and the connection connected to the first connection land and drawn out through the through hole of the first connection land A printed circuit board, comprising a second connection land for soldering the wire tip portion.