The Development of a No-Clean Solder for Radio Frequency Power Module

The pursue of CFC elimination in many industries has opened up opportunity for the development of substitutes of CFC. No-clean solder is just one of the many examples in response to this need. This project describes the development of no-clean solder for radio frequency (RF) Power Module. Nine no-clean solder paste candidates ranging from different solder paste suppliers which are Heraeus, Indalloy, Multicore, Qualitek, Asahi Solders, Demetron, Koki, SCM and Alphametals were selected. Five solder preliminary tests which are flux weight loss, wetting, slump, solder balling, flux spread and four solder printing characteristics which are paste rolling solder coverage, solder fillet and joint texture were used as a tool to select the best no-clean solder that meet the product requirements. Heraeus and Indalloy no-clean solder pastes showed better results compared to others but still required some process changes. Two methods were used in order to eliminate the solder defects which are the development of the new stencil and new soldering reflow profile. These methods able to resolve the solder defects problem such as flux overflow, solder cold joint, solder splashing and solder balling formation. The selected no-clean solder paste together with the normal production solder paste known as control solder paste were further subjected to the paste level evaluations and the reliability tests. It was found that the Heraeus and Indalloy no-clean solder paste are the best candidates for noclean solder process capability. The results of these tests are presented and discussed in this thesis.

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