The soldered bonding between the Sn-Zn-Cu-Bi system and a Cu substrate was studied and reported herein. The alloying compositions were varied to investigate the effects of Zn, Cu, Bi contents on the solders’ melting temperature (Tm), microstructures, wettability and the intermetallic-compound (IMC) bonding with a Cu substrate. The Sn-7Zn and Sn-9Zn exhibited low Tm (198 °C), but poor wettability on the Cu substrates. Both Cu and Bi additions significantly improved the solder wettability. However, the Tm of the Sn-Zn-Cu series increased sharply to about 225 °C by the addition of 4-wt% Cu. The addition of 3-wt% Bi lowered Tm of the Sn-Zn-Cu alloys by 5 °C. The thickness of the IMC layers between solder and substrate was maximum for Sn-9Zn and significantly decreased with the Cu addition. With the addition of Bi to Sn-Zn-Cu, the IMC thickness increased. The aging of 150 °C for 150 hours minimally affected the IMC-bonding thicknesses of most samples; however, micro crack could be observed along the aged IMC layers.
Manufacturing Techniques and Alloying Compositions of Metal Decorative Artifacts in 18th Century, Myanmar
