Comparison of Whisker Growth from Pressure-Induced and Environment-Induced Whisker Growth Test Methods

One of the remaining challenges associated with the use of lead-free materials in electronics is the potential failure risk associated with tin whiskers. Despite intense research in recent years, there are still no accelerated test methods to reliably predict whisker growth in field application conditions. Semiconductor component and electronic system manufacturers rely on a set of environmental exposure conditions defined by industry standards to qualify and monitor plating processes. While these test methods offer a common platform for package qualification, their

value for quantitative whisker-induced failure risk assessment is quite limited. Additionally, these tests are timeconsuming and labor intensive, making it difficult to use for purposes such as process improvement, control, and monitoring.

In this paper, a mechanical indentation method is evaluated for assessing the whisker growth propensity of tin and select tin alloys plated on copper, brass, and alloy 42 substrates. Indentation-induced growth results are compared with responses to standard test conditions including temperature cycling and elevated temperature and humidity.