2004 Volume 45 Issue 3 Pages 759-764
Pb-free microsoldering technology has become important, because complete elimination of lead from electric devices is soon to be enforced. In this work, we studied the application of thermal latent technology of a carboxyl group to Pb-free microsoldering. We found that thermal latent carboxylic acid derivatives could both prevent degradation of a solder alloy under normal conditions and serve as a novel activator when a solder alloy begins to melt. Furthermore, we found that the activator in the flux residue after soldering could be converted into an ester unit which has no influence on electric reliability. Solder paste using thermal latent carboxylic derivatives can be combined to achieve good wettability, high electric reliability and high storage stability, and can be useful for Pb-free microsoldering in response to environmental protection demands.