Various phases formation and reliability of Sn-8Zn-3Bi solder-(PPT)

摘要

Spreading ratio of Sn8Zn3Bi on Au/Ni decreased drastically from 0.3μm of Au-thickness due to production and floating of AuZn IMC in solder. 2. In the joint of Sn15Pb-plated lead with Sn8Zn3Bi, crack was generated by low melting temperature phase of SnPbBi, and the crack propagated during thermal shock test. However, Ni/Au-finished PCB can avoid or retard crack and secure better strength than the Sn37Pb solder. 3. During HTH test, ZnO-phase in Sn8Zn3Bi grew like a long branch, and crack was produced in the branch. The reason seems to be a volume expansion cased by phase transformation from Zn to ZnO.