JPH046211Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Background and Purpose of the Invention] The present invention relates to a semiconductor device coated with resin or glass, and particularly to a semiconductor device in which lead portions exposed and extended from the resin or glass coating layer are plated with tin or solder. In general, semiconductor devices such as ICs are plated with tin or solder on lead portions exposed and extended from a resin or glass coating layer so that they can be easily integrated into a printed circuit board by soldering. When incorporating such a semiconductor device into a printed circuit board,
The lead portion is bent into an appropriate shape using an automatic forming machine in advance, and then the lead portion thus bent is inserted into a predetermined hole of a printed circuit board, and the lead portion inserted into this hole is soldered. As a result, the semiconductor device is mounted on the printed circuit board. However, when bending the lead parts using the automatic molding machine, the same process is performed one after another on a large number of semiconductor devices, and during this process, the automatic molding machine removes the tin or solder plating on the lead parts. It gets rubbed and scraped, and it adheres to the lead part processing jig of the automatic molding machine or accumulates as debris inside the jig, making the processing itself by the automatic molding machine unstable and reducing accuracy. In addition to chipping, the tin or solder plating on the lead part may be chipped.
There was a problem in that the original solderability of the lead portion was degraded. The purpose of the present invention is to solve the above-mentioned drawbacks of the conventional technology and improve the slipperiness of the surface of the lead part plated with tin or solder, thereby making it possible to stably bend the lead part using an automatic forming machine. It is an object of the present invention to provide a semiconductor device having an advantageous structure that can be accurate and maintain the original solderability of the lead portion over a long period of time. [Summary of the invention] In other words, the gist of the invention is that methyl cellulose is applied onto the lead portion that is plated with tin or solder, and stearic acid is further applied on top of that. In the above, both methylcellulose and stearic acid significantly improve the slipperiness of the surface of the tin or solder plating layer by being applied to the surface of the tin or solder plating layer, thereby allowing automatic molding machines to It prevents the tin or solder plating layer from being scratched by scratching, and does not impair the solderability of the tin or solder plating layer even if it is formed as a film on the surface of the tin or solder plating layer. . Methylcellulose is a type of cellulose-based organic material, and is not only inexpensive, but also water-soluble and easy to apply and handle compared to similar products such as nitrocellulose (which requires explosion-proof measures). However, since methylcellulose is water-soluble, it may absorb moisture in the air and discolor, reducing its commercial value. Therefore, stearic acid, which is an oil-based higher fatty acid (expensive), was applied on top of such methylcellulose.

[Table] [Effects of the invention] As is clear from the table above, according to the invention,
By applying methyl cellulose to the lead parts that are plated with tin or solder, and then applying stearic acid on top of that, the lead parts become more slippery, and tin can be easily removed during molding using an automatic molding machine. Alternatively, it can prevent the solder plating layer from being scraped, and in the above case, stearic acid alone is expensive because it is a higher fatty acid, while methylcellulose alone is water-soluble and therefore absorbs moisture in the air and causes discoloration. However, by skillfully combining the two, it is possible to prevent discoloration of the surface of the tin or solder plating layer for a long time using an inexpensive method, and the solderability that the tin or solder plating layer has. This has the effect of being able to maintain and ensure the Conventionally, such semiconductor devices are made of soft metal with tin or solder plating, so when the tin or solder plating goes through a process that involves slipping, such as bending, the tin or solder plating is scraped, making it difficult to process the lead part of the semiconductor device using an automatic molding machine. However, according to the present invention, this problem can be significantly improved and the assembling efficiency can be significantly improved. Both methylcellulose and stearic acid suppress the growth of oxide films formed on the surface of tin or solder plating layers, and stearic acid is particularly effective in improving discoloration resistance. It is possible to maintain and ensure the solderability of the adhesive layer over a long period of time. Therefore, according to the present invention, the commercial value of this type of semiconductor device can be significantly increased.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing an embodiment of the semiconductor device of the present invention, and FIG. 2 is a partial cross-sectional view showing a state in which the lead portion of the semiconductor device is bent. 1... Resin coating layer, 2... Lead portion, 3, 4
...Forming jig.

Claims (1)

[Scope of utility model registration request] In a semiconductor device having a resin or glass coating layer and a lead portion exposed and extended from the resin or glass coating layer, and in which the lead portion is plated with tin or solder, the top of the tin or solder plating on the lead portion is 1. A semiconductor device comprising: coated with methyl cellulose, and further coated with stearic acid.