Shape Control of Electronic Devices by Soldering

Abstract

The authors investigated shape-control technology for electronic devices using the material characteristics of solder.Specifically, the authors developed and put into practical use the following processes and structures: (1) A "Solder bump transfer process" for reducing variation in the solder bump heights. (2) A "Support ball structure", by which high-meltingpoint solder spacers are set on the four corners of a BGA to control the heights of solder balls. (3) A "Solder pouring process", which allows voidless soldering with molten solder poured into metallized parts on electronic devices. We found that the support ball method is effective for heavy BGA structure packages used in high-speed communication. A highquality hermetic sealing package was realized by application of the solder pouring method.