Contributions of Stress and Oxidation on the Formation of Whiskers in Pb-free Solders
Technical Report,01 Jun 2010,01 May 2013
Savannah River National Laboratory Aiken United States
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Understanding the environmental factors influencing formation of tin whiskers on electrodeposited lead free, tin coatings over copper or copper containing substrates is the topic of this study. An interim report summarized initial observations as to the role of stress and oxide formation on whisker growth. From the initial results, two main areas were chosen to be the focus of additional research the demonstration of effects of elastic stress state in the nucleation of whiskers and the confirmation of the effect of oxygen content in the formation of whiskers. Different levels of elastic stress were induced with the incorporation of a custom designed fixture that loaded the sample in a four-point bending configuration and were maintained in an environmental chamber under conditions deemed favorable for whisker growth. The effects of oxygen content were studied by aging substrates in gas vials of varying absolute pressure and different oxygen partial pressure.
- Coatings, Colorants and Finishes
- Metallurgy and Metallography