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|Mechanism of Whisker Growth caused by Corrosion of Solder|
|Keywords: whisker, Pb-free solder, reliability|
|The purpose of this presentation is to observe whisker caused by corroded solder and to propose a new growth mechanism. Recently semiconductor devaices are used in more strict circumstances of humidity and temperature. In these circumstances, we have high risk that great number of whiskers will occur and grow by corrosion of solder. However, this type of whisker will be not almost studied including its mechanism. In the first step of this study we tried to make tin whisker grow by residual stress of corroded solder. We succeeded in growth of whiskers by corroded solder that attack of residual flux for tin-plated Cu-wiring brings about. Maximum length of whisker was observed to be 450 micron-meter. And in the second step, we observed these whiskers using high resolution SEM and TEM. Observed whiskers were located between two corroded solders. In these observations, it was concluded that these whiskers occurred and grew by residual stress of corroded solder and intermetallic compound. And new mechanism of whisker growth was prpposed. We noticed the risk for application of Pb-free solder to these strict circumstances.|
|Yasuhide Ohno, Researcher
University of Tokyo