In this study, a three-dimensional (3D) nonlinear stress analysis of the tin whisker initiation on a pure matte Sn-plated copper substrate is investigated. The structure is subjected to a compressive stress acting at the Sn layer which is generated by the spontaneous chemical reaction of the Sn layer and the Sn5Cu6 layer. The Sn layer is assumed to be an elasto-plastic material. The results presented herein is useful in understanding why the compressive stress in the Sn layer can initiate a tin whisker near the weak spot of a SnOx layer.

Issue Section:
Technical Briefs
Keywords:
tin, copper, stress analysis, whiskers (crystal), substrates, boundary-value problems, surface mount technology, integrated circuit packaging, finite element analysis
Topics:
Boundary-value problems, Compressive stress, Copper, Finite element analysis, Stress, Stress analysis (Engineering), Tin, Chemical reactions, Displacement, Materials properties
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