Atomic migration in eutectic SnBi solder alloys due to current stressing


Current stressing at densities from 2.9 to 7.3 × 104 A/cm2 has significant effects on the atomic migration of eutectic SnBi solder alloys. At lower density (2.9 × 104 A/cm2), electromigration dominates the migration of both Sn and Bi, and drives Sn and Bi atoms to migrate toward the anode side. While at higher densities (4.4 and 7.3 × 104 A/cm2), the enhanced Bi electromigration induces a back stress, which promotes a reversed migration of Sn toward the cathode side. A large number of Sn atoms accumulate at the cathode side and form lumps there.

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The authors wish to acknowledge the financial support of the National Science Council of Taiwan, Republic of China, through Grant No. NSC 95-2221-E-005-143. This work is supported in part by the Ministry of Education, Taiwan, Republic of China, under the ATU plan.

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Correspondence to Chih-ming Chen.

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Chen, Cm., Huang, Cc. Atomic migration in eutectic SnBi solder alloys due to current stressing. Journal of Materials Research 23, 1051–1056 (2008).

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