Monday, October 15 | 1:30pm – 5:00pm | Europe 9
Tin whiskers are hair-like single crystal metallic filaments that grow from tin films. Their unpredictability is the greatest concern and the Aerospace and Defense industries consider tin whiskers the, "greatest reliability risk associated with Pb-free electronics".
The potential failure modes include:
- Direct contact causing an electrical short (arcing). This requires whisker growth of sufficient length and in the correct orientation
- Electromagnetic (EM) Radiation where the whisker emits or receives EM signal and noise at higher frequencies and causes deterioration of the signal for frequencies above 6 GHz. This is independent of whisker length.
- Debris which results from a whisker which breaks off and shorts two leads (primarily during handling). Mitigation efforts can fail when only one source of stress is accounted for. For example, if a Ni layer is used to prevent stress from IMC formation, this will not address whisker formation due to corrosion or external pressure.
All the potential sources of stress for a particular application should be considered in the whisker mitigation process. The various sources of compressive stresses that drive whisker growth are rather well understood but to effectively mitigate tin whisker growth one needs to ensure actions are taken to address ALL sources of stress in an application. A checklist can be used as an aid in this endeavor. This approach would offer a more cost effective and better method of whisker management than the current focus on long term environmental testing.
Who Will Benefit
Design engineers, component/supplier quality engineers, reliability engineers