Composition and heat-treatment effects on the adhesion strength of Sn-Zn-Al solders on Cu substrate

Intermetallic layer growth at the solder/ substrate interface during solder ing and subsequent aging in service can affect bond strength and dimensiona l stability. In this work, interfacial structure and bonding strength studi es were performed on lead-free, Sn-Zn-Al solders as a function of compositi on and aging time. With the x value of Sn-x(5Al-Zn) solder increasing from 5 wt.% to 40 wr.%, the adhesion strength of bonding decreased from 12.2 +/- 0.5 MPa to 3.3 +/- 0.9 MPa while the thickness of the gamma-Cu5Zn8 interme tallic compound layer in intermetallic compound layer increased from less t han 1 mu m to about 2 mu m. Simultaneously, the adhesion strength of Sn-x(5 Al-Zn) solders with x = 5 9, 20, 30, and 40 decreased as the aging time at 150 degrees C increased from 0 to 1,000 hours.