Room temperature interfacial reactions in electrodeposited Au/Sn couples

✍ Scribed by Wenming Tang; Anqiang He; Qi Liu; Douglas G. Ivey

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 959 KB
• Volume: 56
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2008.08.002

✦ Synopsis

Two Au/Sn couples electrodeposited on metallized Si wafers, a Au/Sn couple (Au deposited first) and a Sn/Au couple (Sn deposited first), were employed to study the room temperature interfacial reactions between Au and Sn. The electroplating sequence has a significant effect on the phases and the microstructures of the reaction regions. AuSn 4 and AuSn are formed in the as-deposited Au/Sn couples, while Au 5 Sn and AuSn are formed in the as-deposited Sn/Au couples. Upon ageing, AuSn 2 formation depends on the Sn (Au) content (i.e. the Sn (Au) layer thickness) in the Au/Sn (Sn/Au) couples. In aged Au/Sn couples, with 1.5 lm of Au and 3 lm of Sn, AuSn, AuSn 2 and AuSn 4 are sequentially distributed in the reaction region with fine Kirkendall voids at the AuSn/Au interface. In the aged Sn/Au couples, with 15 lm of Sn and 1.5 lm of Au, AuSn is distributed on either side of the original Sn/Au interface, while Au 5 Sn only exists on the Au side. The presence of a thin interfacial SnO 2 film significantly affects phase formation and reaction kinetics.