JPH06177524A - Solder feeding sheet - Google Patents

Abstract

PURPOSE:To provide a means with which a defective electronic part can be resoldered to a printed substrate in a simple manner. CONSTITUTION:A solder film 8 is formed on the position corresponding to the land 6 of the printed substrate 4 of the sheet 7 which is formed by the material having the property which activates the solder same as a flux, and it is used as the solder feeding sheet 7 of an electronic part 1. As a result, even when the electronic part 1 has a narrow pitch lead 3, it can be resoldered easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder supply sheet used for re-soldering electronic parts on a printed circuit board.

[0002]

2. Description of the Related Art The process of mounting electronic components on a printed circuit board includes the steps of forming solder on the lands (electrodes) of the circuit pattern on the printed circuit board by means of cream solder or solder precoat, and the leads of the electronic components on the land. The process comprises the steps of landing on the printed circuit board and mounting it on a printed circuit board, sending the printed circuit board to a heating furnace to heat and melt the solder, and then cooling and solidifying the melted solder to perform soldering.

After the electronic components are soldered to the printed circuit board as described above, a quality inspection of the electronic components is performed, and it may be necessary to re-sold the electronic components depending on the inspection result. The soldering was performed again as follows.

That is, the soldering portion of the defective electronic component is heated and melted to remove the electronic component from the printed circuit board, and then the lead of the electronic component is landed and mounted on the land of the printed circuit board. The solder heated and melted by is supplied to the land and solidified. Conventionally, such work has been performed manually by a worker.

[0005]

However, the above-mentioned conventional means has a problem that it takes a lot of time and labor because the molten solder has to be applied to each of a large number of lands by an operator's manual work. Further, in recent years, the number of leads of electronic parts has increased, and the pitch of leads and lands has become narrower accordingly. Therefore, in the above-mentioned conventional means, each of a large number of lands having a narrow pitch is used. When applying the solder, there is a problem that the solders on adjacent lands are connected to each other and a solder bridge is very likely to occur. Incidentally, in recent years, the number of leads and lands is often 100 or more, and the pitch is 1.0 mm or less, which is a very narrow pitch.

Therefore, an object of the present invention is to provide a solder supply sheet which can easily re-solder an electronic component having a narrow pitch lead to a land of a printed circuit board.

[0007]

To this end, according to the present invention, a solder film is formed at a position corresponding to a land of a printed circuit board of a sheet formed of a substance having a property of activating solder like flux. This is a solder supply sheet.

[0008]

According to the above structure, if the solder film formed on the solder supply sheet is matched with the land, the leads of the electronic component are matched with the solder film, and the solder film is heated and melted, the electronic component is easily formed. Can be re-soldered.

[0009]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a perspective view of an electronic component, a solder supply sheet, and a printed circuit board. A large number of leads 3 extend from the molded body 2 of the electronic component 1. t is the lead pitch. For the convenience of drawing, the number of leads 3 of this electronic component 1 is 5 for each side, and a total of 20. However, in recent years, several 10 or more for each side and a total of 100 or more for narrow pitch leads are used. The number of parts is increasing, and the solder supply sheet of the present invention is particularly useful for re-soldering electronic parts having such narrow-pitch leads.

A circuit pattern 5 is formed on the upper surface of the printed circuit board 4.
And the land 6 is formed at the end of the circuit pattern 5.
Are formed. A solder film 8 is formed on the surface of the solder supply sheet 7. The solder film 8 is formed at a position corresponding to the land 6 of the printed board 4. The solder film 8 is formed by sticking a sheet-shaped solder onto the solder supply sheet 7 or by vapor deposition. When re-soldering the lead 3 to the land 6, the solder film 8 is aligned with the land 6 and the solder supply sheet 7 is used.
Is placed on the printed circuit board 4, and the leads 3 are further connected to the solder film 8
The electronic component 1 is mounted on the solder supply sheet 7 so that the pitch t of the lands 6 and the solder film 8 is the same as the pitch t of the leads 3.

The solder supply sheet 7 is made of the same material as the flux whose main component is pine. Flux is a kind of activator used when soldering,
It activates the solder that is heated and melted to improve the wetting property of the solder. Therefore, by forming the solder supply sheet 7 from a similar substance having a property equivalent to that of the flux, the solder supply sheet 7 is melted together with the solder film 8 and activated during the heat treatment.

Next, a method of re-soldering the electronic component 1 will be described with reference to FIGS. 2 (a) to 2 (e).

FIG. 2A shows the printed circuit board 4 on which the electronic component 1 determined to be defective as a result of the quality inspection is mounted. Therefore, the electronic component 1 is removed from the printed circuit board 4 by heating and melting the soldering portion (see FIG. 2).
(See (b)). Next, as shown in FIG. 2C, the solder supply sheet 7 is placed on the printed board 4. In this case, the solder film 8 is matched with the land 6, but if the solder supply sheet 7 is a transparent or translucent transparent sheet, the solder film 8 can be easily attached to the land 6 while seeing the land 6 from above. Can be installed by matching. In this way, the solder supply sheet 7
Just place the printed circuit board 4 on the
The solder film 8 can be formed thereon.

Next, as shown in FIG. 2D, the leads 3 of the electronic component 1 are landed on the solder film 8 and mounted. Next, when the printed circuit board 4 is heated in a heating furnace, the solder film 8 melts,
Then, when the solder film 8 which is cooled and melted is solidified, the lead 3 is soldered to the land 6 (FIG. 2E). When the solder film 8 is heated and melted as described above, the solder supply sheet 7 whose main component is pine tree is also melted together with the solder film 8, and the melted solder film 8 is activated and the lead 3 is landed. 6 can be soldered firmly.

[0016]

As described above, according to the solder supply sheet of the present invention, electronic parts can be easily soldered. In particular, the solder film can be easily formed with a narrow pitch, so even if there are many leads and lands and even with a narrow pitch, it can be easily soldered, and by forming it with a substance that activates the solder like flux. The leads can be soldered to the land with good wetting property, and after soldering, the solder supply sheet can also be melted and eliminated from the substrate.

[Brief description of drawings]

FIG. 1 is a perspective view of a solder supply sheet and a printed circuit board for an electronic component according to an embodiment of the present invention.

FIG. 2A is a side view of an electronic component according to an embodiment of the present invention during re-soldering. FIG. 2B is a side view of an electronic component according to an embodiment of the present invention during re-soldering. Side view during re-soldering of electronic component of one embodiment (d) Side view during re-soldering of electronic component of one embodiment of the present invention (e) Re-soldering of electronic component of one embodiment of the present invention Inside view

[Explanation of symbols]

 4 Printed circuit board 6 Land 7 Solder supply sheet 8 Solder film

Claims (1)

[Claims] 1. A solder supply sheet comprising a solder film formed of a substance having a property of activating solder and having a solder film formed at a position corresponding to a land of a printed circuit board.