JPS62299098A - Method of mounting parts on printed wiring 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 3. Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a surface-mounted electronic component having a large number of connection terminals led out at equal intervals from an end face of a main body. This invention relates to printed wiring boards.

(Summary of the Invention) The present invention provides a printed wiring board for a surface-mounted electronic component having a large number of connection terminals led out at equal intervals from an end surface of a main body, and a group of conductive foils on the front two printed wiring U boards. By applying solder paste for reflow soldering to the conductive foil located at both ends of the conductive foil in an area sufficiently larger than the area of the conductive foil located at both ends, connection failures of connection terminals of surface-mounted electronic components can be prevented. It is designed to prevent.

(Prior Art) Conventionally, when soldering a surface mount component having a large number of connection terminals led out at equal intervals from the end surface of a main body to a printed wiring V board, it is necessary to solder a large number of connection terminals of the surface mount component to a printed wiring V board. Each of the conductive foils arranged at equal intervals on the printed wiring board was preliminarily provided on the printed wiring board as shown in FIG.
Join with paste 6 and solder (
The first method is adopted. For example, the second edition published by Nikkan Kogyo Shimbunsha
65 No. 6 P, 45-47 describes riff[]-soldering.

(Problems to be Solved by the Invention) However, in the conventional mounting method of surface mount components on a printed wiring board, a surface mount component such as a flat pack TC is attached to a printed wiring board 1 with an electronic component 2 as shown in FIG. Connection terminal 3.3...
Distribute the conductive foil 4.4... to the relevant position corresponding to .
As illustrated in Fig. 4, when reflow soldering is performed between the connection terminals 3.3... and the conductive foil 4.4..., the solder 5 does not come into contact with the connection terminals. However, as shown in part A in FIG. 4, there is a problem in that a connection failure occurs between the conductive foil and the VC terminal located at both ends. This is the connection terminal 3.3 of the electronic component 2...
This is thought to occur because the forming angle of the connection terminals located at both ends of the back of the screen is much larger than that of all other connection terminals. Therefore, in order to eliminate the defect of poor connection of the contact Rg terminals located at both ends, it is necessary to correct the bending of the connection terminals. To correct such connection terminals,
Although it is possible to do this one by one manually using a bottle set or the like, the work efficiency is extremely low, leading to high manufacturing costs, and it is extremely difficult to adjust the angle of the connecting terminals.

Moreover, a lead correction method for flat pack components is disclosed in Japanese Patent Application Publication No. 12052/1983.

However, since the molding machine molds the connection terminals of all flat pack ICs, it requires a large number of molds to press the connection terminals, and also molds to precisely straighten the connection terminals to eliminate springback and other effects. The disadvantage was that it was extremely difficult to design. However, this drawback led to an increase in manufacturing costs due to an increase in the number of surface component mounting steps.

The present invention solves these conventional drawbacks,
The purpose of this is to prevent connection failures caused by contact between the conductive foils located at both ends of the group of conductive foils arranged at equal intervals on the printed wiring board and the connecting terminals of the opposing surface-mounted electronic components. An object of the present invention is to provide a method for attaching a surface mount component to a printed layout i1 board that can be used.

(Means for Solving the Problems) In order to solve the above problems, the present invention applies a solder paste for reflow soldering to the conductive foils located at both ends of the conductive foil group on the printed wiring board. The area is sufficiently larger than the area of the 81 wires located at both ends to prevent defective fl connection due to solder.

(Function) According to this mounting method, the solder paste is applied to the conductive foils located at both ends of the conductive foil group in a direction that is sufficiently larger than the area of the conductive foils located at both ends, and where there is no adjacent conductive foil. Because the solder paste is applied to both ends, even if there is some misalignment due to screen printing or other methods, the solder paste can be applied uniformly without contacting adjacent solder pastes. During reflow soldering, the solder paste is applied to both ends The conductive foil is attracted by surface tension to the part of the conductive foil located at the ends of the conductive foil, preventing a short circuit between adjacent conductive foils and preventing a connection failure between the conductive foil located at both ends and the opposing connection terminal. be done.

(Example) Hereinafter, the present invention will be described with reference to drawings of examples. FIG. 1 shows an embodiment of the present invention, in which solder paste 6 is placed at both ends of a group of conductive foils 4, 4, . It is applied in a direction that is about 2 to 3 times larger than the area of the conductive foil d and where there is no adjacent conductive foil, and then the surface mount component 2 is mounted and reflow soldered. When reflow soldering is performed in this way, the solder paste applied to the conductive foils located at both ends is melted at the conductive foils located at both ends without intersecting with the solder paste adjacent to each other, and becomes solder 5. . Therefore, as mentioned above, among the connection terminals 3, 3, etc. of the electronic component 2, there is a very large variation in the forming angle of the connection terminals located at both ends, so the solder 5
Since the conductive foils do not come into contact with the connecting terminals, there is no possibility that a connection failure will occur between the conductive foils located at both ends and the connecting terminals, as shown in part A in FIG. Here, the reason why the solder paste application area is selected to be 2 to 3 times larger will be explained.

The greater the amount of solder paste applied, the lower the defective connection rate. However, if the amount of solder paste applied is too large, adjacent solder pastes will intersect with each other, and there is a risk that a short circuit will occur due to the excess solder paste between conductors. Also, if the solder paste application area is the same as the conductive foil area, there is no risk of short circuits, but
Connection failure rate increases. Therefore, when we investigated the relationship between the amount of solder paste applied and the solder defect defect rate, we found that the solder paste is applied to the conductive foils located at both ends to an area 2 to 3 times larger than the area of the conductive foils located at both ends. It can be seen that if this is selected, the defective rate will be minimized and it is appropriate.

In the embodiment described above, the solder paste 6 is applied to the conductive foils located at both ends of the group of conductive foils 4, 4, etc. arranged in parallel on the printed wiring board 1. It is applied in a direction that is about 2 to 3 times larger than the area and there is no adjacent conductive foil, and the variation in the forming angle of the connecting terminals located at both ends of the connecting terminals 3.3... is 10
Even when surface-mounted components such as flat pack ICs with an angle of ~20° are mounted and reflow soldered, good soldering can be achieved without causing connection failures.

(Effects of the Invention) As explained above, the present invention has an area approximately two to three times larger than the area of the conductive foils located at both ends of the conductive foil group arranged at equal intervals on the printed wiring base, and Since it is applied in a direction where there are no adjacent conductive foils, adjustment of the solder suspension can be made very easily, and reflow soldering can greatly reduce the connection failure rate of flat pack ICs and the like. In addition, since there is no need to correct the bending of the connection terminals of conventional flat pack ICs, the mounting process can be significantly simplified, and the number of manufacturing originals can be reduced.

[Brief explanation of drawings]

Fig. 1a is a front view showing an embodiment of the present invention, Fig. 1 is a partially enlarged perspective view thereof, and Fig. 2 is an explanation showing mounting a general flat back IC on a printed wiring board 1. Figure 3a is a front view showing an example of conventional solder paste application, Figure 3FAb is a partially enlarged perspective view of the same, and Figure 4a is a typical flat pack IC soldered to an I2 board. FIG. 4 is a partially enlarged perspective view. 1...Printed wiring board 2...Surface mount component 3...Connection terminal 4...3g Conductive foil...Solder 6...Solder paste A...Poor connection due to solder Applicant: Seiko Electronic Industries Agent Co., Ltd. Patent Attorney Mogami (1 other person) Engraving of drawings (no change in content) Engraving of drawings of Figures 1 and 2 (no change in content) Engraving of drawings (no change in content) Procedure supplement Correct -1F (Method) % formula % 2 Name of the invention Method for mounting double-printed wiring boards l Person making the amendment August 26B, 1985

Claims (1)

[Claims] A surface-mounted electronic component having a large number of connecting terminals led out from the end surface of the main body at equal intervals is mounted on a printed wiring board, and the numerous connecting terminals of the electronic component are mounted at equal intervals on the printed wiring board. In the method of fixing conductive foils arranged on the printed wiring board by reflow soldering, solder paste for reflow soldering is applied to the conductive foils located at both ends of the group of conductive foils on the printed wiring board. A method for mounting a printed wiring board, characterized in that the area of the conductive foil is sufficiently larger than the area of the conductive foil located at the surface of the printed circuit board.