Influence of Cu content on microstructure, grain orientation and mechanical properties of Sn-xCu lead-free solders
(1. Department of Industrial Engineering, School of Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok 10520, Thailand;
2. Department of Industrial and Production Engineering, Faculty of Industry and Technology, Rajamangala University of Technology Rattanakosin Wang Klai Kangwon Campus, Prachuapkhirikhan 77110, Thailand)
2. Department of Industrial and Production Engineering, Faculty of Industry and Technology, Rajamangala University of Technology Rattanakosin Wang Klai Kangwon Campus, Prachuapkhirikhan 77110, Thailand)
Abstract: The effect of Cu content on the microstructure, grain orientation and mechanical properties of Sn-xCu (x=0-4.0 wt.%) lead-free solder was studied. Results showed that added Cu induced the formation of intermetallic phases. Only the η Cu6Sn5 and ε-Cu3Sn phases were present in the β-Sn matrix. For all contents, the strongly preferred orientation of the β-Sn phase was formed on the {001} plane. In Sn doped with 1.0 wt.% Cu, the η-Cu6Sn5 phase exhibited the preferred orientation of {0001} plane, whereas doping with 3.0 or 4.0 wt.% Cu transformed the preferred orientation to the {010} plane. In addition, only the {0001} and planes were present in the ε-Cu3Sn phase. The high Cu contents contributed to an increased number of low-angle boundaries, high residual strain, tensile strength and microhardness.
Key words: lead-free solder; Sn-Cu alloys; crystallographic orientation; microstructure; intermetallics; mechanical properties