Release Time:2019-03-14  Hits:

Indexed by: Conference Paper

Date of Publication: 2018-01-01

Included Journals: CPCI-S

Page Number: 265-269

Key Words: Lead-free solder; low temperature; Sn-Bi-Ag; mechanical property; microstructure; cluster-plus-glue-atom (CPGA) model

Abstract: Novel low-temperature lead-free Sn-Bi-xAg solder alloys were designed by cluster-plus-glue-atom (CPGA) model for low-temperature Al-Cu solder technology. The microstructure, melting behavior, wettability, interfacial reaction and mechanical properties of Sn-Bi-xAg solders were investigated. Both Sn-56.93Bi-0.49Ag and Sn-57.02Bi-1.96Ag solders were near-eutectics with a narrow melting temperature range of 138-140 degrees C, indicating that the small substitution of Ag atoms in CPGA model had little effect on the melting behavior. The microstructure of bulk solders in Sn-57.02Bi-1.96Ag bulk solder consisted of black Ag3Sn phase, which was little in Sn-56.93Bi-0.49Ag bulk solder. The high Ag content Sn-Bi-xAg solder shows a better wettability on both Al and Cu substrates than that of low Ag content solder. A continuous Ag2Al intermetallic compound (IMC) formed at Sn-57.02Bi-1.96Ag/Al interface, which was favorable for Sn-Bi-xAg soldering the Al substrate, as well as improved the bonding strength of the solder joints. The scallop-like Cu6Sn5 formed at the both Sn-56.93Bi-0.49Ag and Sn-57.02Bi-1.96Ag Sn-BixAg/Cu interface. The shear strength of the 56.93Bi-0.49Ag and Sn-57.02Bi-1.96Ag solder joints is 35.79 MPa and 30.07 MPa, respectively.