JPS62163392A - Soldering of electronic parts - 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 [Industrial Application Field] The present invention relates to a soldering method for mounting electronic components on a printed wiring board.

[Conventional technology]

A method of soldering electronic components to a printed wiring board will be explained with reference to FIG. FIG. 2 is a perspective view showing soldering of electronic components to a printed wiring board.

As shown in the figure, in the flow soldering method, in order to electrically and mechanically connect the connection terminals 2 of the electronic component 1,
After applying cream solder on the soldering conductors (hereinafter referred to as pads) 4 provided in parallel on the printed wiring board 3 corresponding to the connection terminals 2, and mounting the connection terminals 2 on each of them, Soldering is performed by heating and melting the cream solder.

In the above method, when the pitch of the connection terminals 2 of the electronic component 1 is large (for example, 1.27 mm), cream solder is applied over almost the entire surface of the pad 4; In the case of ゜63mm1, if cream solder is applied over almost the entire surface of pad 4 in the same way, when it melts, the cream solder flows out from above pad 4 and adjacent pads 4 become conductive (
Solder bridging) may occur.

Conventional measures for preventing the above phenomenon will be explained using FIG. 3. FIG. 3 is a plan view showing conventional cream solder application. Conventionally, countermeasures against the above phenomenon include: (1) making the width of the cream solder 5 to be applied smaller than the width of the pad 4 as shown in FIG. The amount of cream solder 5 to be applied has been reduced by reducing the thickness from about 2 m to 0.1 mm or less.

[Problem that the invention seeks to solve]

However, in the above measure (2), since the width to which the cream solder 5 is applied is extremely narrow, the cream solder 5 does not pass through the mask (not shown) of the cream solder printing machine and is not printed on the pad 4 (the solder is also There was a problem in that the following phenomenon occurred.

Next, the problems with the above countermeasure (2) will be explained using FIG. 4. FIG. 4 is a side view showing how connection terminals are placed on pads. As shown in the figure, the connection terminal 2 of the electronic component 1
A bent portion 6 for contacting the top of the pad 4 is formed at the end of the pad. The angle of this bent portion 6 varies,
If the angle is large, the distance between the base 6b of the bent part 6 and the top of the pad 4 will be large, and the soldering to the pad 4 will be done only at the tip 6a of the bent part 6. If the thickness is small, there is a problem in that unsoldered areas are likely to occur.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide a technique that prevents solder bridging and enables reliable soldering.

[Means for solving problems]

In the present invention, cream solder 5 is applied onto a plurality of pads 4 arranged in parallel on a printed wiring board 3 corresponding to a plurality of connection terminals 2 of an electronic component, and formed at the ends of a plurality of connection terminals 2. The bent portions 6 to be bent are respectively placed on the plurality of pads 4,
In the method for soldering electronic components in which cream solder 5 is melted and soldered, for every other pad 4 among the plurality of pads 4, only the part 4a corresponding to the tip 6a of the bent part 6 is soldered. For other pads 4 among the plurality of pads 4, cream solder 5 is applied only on the part 4b corresponding to the base 6b of the bent part 6, and on the part 4a corresponding to the tip 6a of the bent part 6. The amount of cream solder 5a applied is set to be small.

[Effect]

According to the present invention, for every other pad 4 among the plurality of pads 4, only the portion 4a corresponding to the tip 6a of the bent portion 6 of the connecting terminal 2 is applied, and for the other pads 4 among the plurality of pads 4. Since the cream solder 5 is applied only on the portion 4b corresponding to the base 6b of the bent portion 6 of the connection terminal 2, the cream solder 5 applied on adjacent pads 4 are very close to each other. In addition, since the amount of cream solder 5a applied on the portion 4a corresponding to the tip 6a of the bent portion 6 of the connection terminal 2 is set to a small amount, the probability of a solder bridge occurring is reduced.

Furthermore, since the width of the cream solder 5 to be applied can be made as large as the pad 4, reliable printing can be performed using a cream solder printing machine, thereby reducing the probability of solder leakage.

Furthermore, since the probability of a solder bridge occurring is small as described above, the amount of cream solder 5b applied on the portion 4a corresponding to the base 6b of the bent portion 6 of the connecting terminal 2 is
Even if the distance between the base portion 6b and the pad 4 is large, it can be set to a required amount to ensure soldering, so the probability that unsoldering will occur is reduced.

〔Example〕

Embodiments of the present invention will be described using the drawings. Figure 1 (m
1 (bl fcl is a plan view and a side view showing one embodiment of the present invention, and FIG. 5 is a plan view showing melting of cream solder.

As shown in the same figure (al), the pads 4 are arranged in four rows (with a pitch of 0.63 mm) in correspondence with the connection terminals 2 of electronic components (see FIG. 2) on the printed wiring board. Cream solder 5a is applied only to the outer half portion 48 of the upper surface of every other TL pad 4 arranged in this way. , the cream solder 5b is applied only to the inner half portion 4b of the top surface.As can be seen from the figure, the width to which the cream solder 5 is applied is approximately the same as the width of the top surface of the pad 4. , the printing by the cream solder printing machine is reliable.

In addition, as shown in the same figure (bl), in the case of cream solder 5a, soldering is performed at the tip 6a of the bent part 6 of the connecting terminal 2 of the electronic component, so there is a possibility that unsoldered parts will occur. Since the amount of cream half IB5a is low, the amount of cream half IB5a may be small (for example, the thickness should be 0°1 mm or less).
. On the other hand, as shown in FIG. Considering the variation, the amount of cream solder 5b is set to the amount necessary to avoid the occurrence of unsoldered parts (for example, the thickness is set to 0.2 mm).

Furthermore, as shown in FIG. 5, in this embodiment, cream solder 5
Since the application is performed on the outside, inside, and outside of the upper surface of the pad 4, it is alternated between adjacent pads 4, and even when the cream solder 5 is melted, the cream solder on the adjacent pad 4 is applied. 5 (5a p 5
b) A considerable distance can be secured between the two. Therefore, solder bridges do not occur between adjacent pads 4.

In addition, the amount of cream solder 5a can be set to a small value, and the amount of cream solder 5b can be set to the minimum necessary amount to ensure soldering, so the amount of cream solder flowing out can be minimized (eliminated). , which is extremely effective in preventing solder bridging.

〔Effect of the invention〕

As explained above, according to the present invention, for every other pad among the plurality of pads, only the part corresponding to the tip of the bent part of the connection terminal and for the other pads among the plurality of pads. In contrast, cream solder is applied only to the area corresponding to the base of the bent part of the connection terminal, so the cream solder applied to adjacent pads does not come close to each other, and the connection terminal Since the amount of cream solder applied to the portion corresponding to the tip of the bent portion is set to be small, there is an effect that the probability of a solder bridge occurring is reduced.

Furthermore, since the width of the applied cream solder can be made as large as the pad, reliable printing can be performed using a cream solder printing machine, which has the effect of reducing the probability of solder leakage.

Furthermore, since the probability of a solder bridge occurring is small as described above, the amount of cream solder applied on the part corresponding to the base of the bent part of the connection terminal can be reduced even if the distance between the base and the pad is large. Since it can be set to the required amount to ensure reliability, it is effective in preventing the occurrence of unsoldered parts.

[Brief explanation of drawings]

Figure 1 (al (cl) is a plan view and side view showing one embodiment of the present invention, Figure 2 is a perspective view showing soldering of electronic components to a printed wiring board, and Figure 3 is a conventional cream soldering method. 4 is a plan view showing the application of solder, FIG. 4 is a side view showing the placement of the connection terminal on the pad, and FIG. 5 is a plan view showing the melting of the cream solder of the embodiment shown in FIG. : Electronic component, 2: Connection terminal of electronic component, 3 Niblint wiring board, 4: Pad, 4a: Outer half of the top surface of the pad, 4b = Inner half of the top surface of the pad, 5: Cream solder, 5a: A small amount of cream solder applied to the outer half of the upper surface of the pad, 5b: Cream solder applied to the inner half of the upper surface of the pad, 6: Bent portion, 6
a: Tip of the bent portion, 6b = Base of the bent portion. (a) (b) (C) An embodiment of the present invention Fig. 1 Soldering of electronic components to a printed wiring board Fig. 2 Conventional cream solder ink cloth Fig. 3

Claims (1)

[Claims] Cream solder (5) is applied to a plurality of electronic component soldering conductors (4) arranged in parallel on a printed wiring board (3) corresponding to a plurality of connection terminals (2) of electronic components. bending portions (6) formed at the ends of the plurality of connection terminals (2).
In the method of soldering electronic components, the electronic components are soldered by placing each on the plurality of conductors (4) and melting cream solder (5), wherein every other conductor among the plurality of conductors (4) is soldered. , there is a portion (4) corresponding to the tip (6a) of the bent portion (6).
a) Apply cream solder (5) only on the top and, for other conductors among the plurality of conductors (4), only on the part (4b) corresponding to the base (6b) of the bent part (6). The part corresponding to the tip (6a) of the bent part (6) (
4a) A method for soldering electronic components, characterized by setting a small amount of cream solder (5a) applied thereon.