JPS61267395A - Soldering of flat package type ic - 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] [1 Already Required] When mounting a flat package IC on a printed circuit board by soldering, a protector is used, and the solder adheres to the side of the package in the form of a bridge, causing short-circuiting of the leads. to prevent

[Industrial application field]

The present invention relates to an improved method for soldering flat packaged ICs.

In recent years, in order to make it possible to mount integrated circuits on printed circuit boards with high density, the lead spacing of integrated circuits has been reduced to lead them out of chip-like packages, and they can be mounted directly on printed circuit boards without using through holes. 2. Description of the Related Art So-called flat package ICs that are soldered to conductive patterns are widely used.

Frasotopasoke with small lead spacing like this
When soldering a '-shaped IC, care must be taken to avoid solder from adhering in the form of a bridge between the leads.

[Conventional technology]

In conventional soldering of flat package ICs, as shown in the process diagram of FIG. 2, first, as shown in FIG.
A lead component 2 is mounted, its terminal 2a is inserted into a through ball, and the terminal is bent to prevent the lead component 2 from falling off from the print 1 and the board 1.

Next, as shown in Fig. 2 (b+), apply an adhesive 3
Apply.

Then, as shown in Fig. 1 fcl, a flat package type T
Align the leads 5 of the C4 with the pads of the corresponding conductor pattern 1, bring the bottom of the package 4^ into close contact with the adhesive 3, heat and harden the adhesive 3, and temporarily attach the flat package IC 4 to the printed circuit board 1. stick.

In this state, the surface of the printed circuit board 10 to which the flat package IC 4 is fixed is
Solder 6 in a molten state is dipped into a solder tank 7 containing it.

At this time, since the package 4A is made of synthetic resin, the solder 6 does not adhere to any part other than the package 4A and the pattern of the printed circuit board 1, but only to the metal surface. Therefore, the terminal 2a of the lead component 2 is soldered to each through ball, and the lead 5 of the flat package type C4 is soldered to each pad portion.

[Problem that the invention seeks to solve]

However, as shown in the front view of FIG. 3, the method for soldering the conventional flat package IC is as follows:
The pinch is small (for example, 1.2°0.8. 0.6
5 mm), the solder 6 penetrates and adheres between the leads 5 on the side of the package 4A, which would not normally adhere, due to capillary action, forming a bridge portion 6a, and the adjacent 5 leads are bridged by the solder, causing a short circuit. There is a problem.

[Means for solving problems]

In order to solve the above-mentioned conventional problems, the present invention, as shown in FIG. A protector 10 made of synthetic resin having comb teeth 12 in contact with each other is used, and the adjacent leads 5 are soldered while being shielded by the respective comb teeth 12.

[Effect]

According to the above means, since the comb teeth 12 are in close contact between the leads 5 on the side surface of the package 4 where the leads 5 are arranged in parallel, the solder does not penetrate and adhere to this part.

In addition, it is possible that solder adheres to the outer surface of the comb teeth 12 and causes a bridge, but after soldering, the protector 10
Since it is removed, the bridged solder is cut and removed.

Therefore, when the flat package type C4 is soldered and mounted on the printed circuit board 1, adjacent leads will not be short-circuited.

〔Example〕

The present invention will be specifically explained below with reference to illustrated examples. Note that the same reference numerals indicate the same objects throughout the figures.

FIG. 1 is a process diagram of one embodiment of the soldering method of the present invention.
fa) is a front perspective view of soldering, and (b) is a rear side view of soldering.

As shown in FIG. 1 (al), the protector 10 is a molded product made of synthetic resin, and is a flat package type IC4.
Elastic comb teeth 12 are vertically arranged and molded around a square plate-shaped protector main body 11 that is in close contact with the upper surface of the package 4.

The comb teeth 12 are inserted between the respective glue boards 5 with the protector 10 attached to the flat package IC 4, and are formed to come into elastic contact with the side surface of the package 4Δ.

With such a protector 10 attached, the flat package IC 4 is temporarily fixed with adhesive 3 with the leads 5 aligned with the corresponding pads of the conductive pattern IA.

Thereafter, it is dipped into a solder bath 7 containing molten solder 6, and the leads 5 are soldered to the corresponding pad portions of the conductor patterns IA.

Therefore, as shown in FIG. 1(b), since the comb teeth 12 are in close contact between the leads 5 on the side surface of the pancage core where the leads 5 are arranged in parallel, the solder penetrates and adheres to this part. Never.

Furthermore, solder often adheres to the outer surface of the comb teeth 12 and causes bridging, but since the protector 10 is removed after soldering, the bridging solder is cut off and removed.

Further, unlike the illustrated example, if the leads 5 are arranged in parallel on the four circumferential sides of the flat package IC 4, it goes without saying that comb teeth can be provided on the four circumferential sides of the protector body.

Note that the present invention is applicable not only to soldering using a solder dip, but also when soldering leads by printing solder paste, or by applying preliminary solder to the pad portion of a conductive pattern and reflowing the solder. This can be applied when

〔Effect of the invention〕

As described above, the present invention has an excellent effect in that adjacent leads are not short-circuited by adhering solder by attaching a protector to a flat package IC and soldering it.

[Brief explanation of drawings]

Figure 1 is a process diagram of one embodiment of the soldering method of the present invention, (a) is a front perspective view of soldering, (b) is a rear side view of soldering, and (al , (b), (cL) (d) are side views showing the steps of the conventional method, and Fig. 3 is a front view of a flat package IC soldered by the conventional method. In the figure, ■ is a printed circuit board,゛IA is the conductor pattern, 2 is the lead component, 3 is the adhesive, 4 is the flat package type RC. 4A is the package, 5 is the lead, 6 is the solder, 6a is the bridge part, 7 is the solder bath, 10 is the protector, 12 indicates comb teeth. Tonobu Protefuku (α) /1.

Claims (1)

[Claims] The comb teeth (
A protector (10) made of synthetic resin having 12) is attached to the flat package IC (4), and each lead (5) of the flat package IC (4) is connected to the printed circuit board (1). Corresponding conductor pattern (IA)
A method of soldering a flat package type IC, which is characterized by soldering to a flat package type IC.