Hits:

Indexed by:期刊论文

Date of Publication:2017-04-01

Journal:JOURNAL OF ELECTRONIC MATERIALS

Included Journals:SCIE、EI、Scopus

Volume:46

Issue:4

Page Number:1931-1936

ISSN No.:0361-5235

Key Words:Soldering; thermomigration; interfacial reaction; intermetallic compound; Sn-9Zn; dissolution

Abstract:Interfacial reactions in Ni/Sn/Ni and Ni/Sn-9Zn/Ni micro solder joints during thermomigration (TM) have been studied by reflowing solder joints on a hot plate. Asymmetrical growth and transformation of interfacial intermetallic compounds (IMCs) were clearly observed. The growth of the Ni3Sn4 IMC in the Ni/Sn/Ni solder joints was always fast at the cold end and relatively slow at the hot end. Only asymmetrical growth of the Ni5Zn21 IMC in the Ni/Sn-9Zn/Ni solder joints occurred at the beginning because Zn was the dominant TM species; however, asymmetrical transformation of the Ni5Zn21 IMC also occurred under the combined effect of Zn depletion and Ni dissolution and migration, resulting in formation of a thin tau-phase layer at the hot end and a thick tau-phase/Ni5Zn21/tau-phase sandwich structure at the cold end. TM of Ni and Zn atoms was identified towards the cold end, being responsible for the abnormal IMC evolution. Addition of Zn was found to slow the TM-induced IMC growth and Ni dissolution.