ACTA

Electrical Characterization of β→α-Sn Transition in High Tin Content Solder Alloys with Different Inoculators

B. Illés^a, A. Skwarek^b, R. Bátorfi^a, T. Hurtony^a, G. Harsányi^a
^aBudapest University of Technology and Economics, Department of Electronics Technology, Budapest, Hungary
^bInstitute of Electron Technology, Kraków Division,Kraków, Poland

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The identification of allotropic transition of the metallic β-Sn to non-metallic α-Sn in Sn-rich solders joints is crucial for electronics working in sub-zero temperatures. This phenomenon was characterized by electrical resistance measurements in SnCu1 and Sn99Ag0.3Cu0.7 alloys inoculated with InSb, CdTe and α-Sn. Samples were stored at -18° for 10 weeks. The transition showed characteristic differences at the different alloys and inoculators, like different nucleation, growth and the saturation stages. Although the presence of α-Sn initiates the transition faster than the other inoculators, but the higher diffusion rate of the non-tin inoculators results in much more serious destruction of the samples. The results of the electrical resistance measurements were validated with metallurgical cross-sections.

DOI:10.12693/APhysPolA.135.935
topics: tin pest, electrical resistance, allotropic transition, solder alloy, inoculator