| Abstract Scope |
The interfacial reactions in the Cu/Sn/Ni sandwich couple with three different Sn layer thicknesses (5, 10, and 15 μm) were investigated. Couples were reflowed at 250 °C for 1, 3, and 5 min, then aged at 180 °C for up to 300 h. The results showed that when the Sn layer thickness increased, it need more time to consume the Sn layer completely. When the couples were reflowed for 3 and 5 min, the thicker Sn layers resulted in delayed phase transitions. After 1 min reflow, the Cu3Sn layer thickness increased with the increase in Sn thickness. At the same Sn thickness, both Sn consumption and phase transformation occurred earlier as reflow time increased, except in the Cu/Sn(15 μm)/Ni couples. Additionally, the Cu3Sn thickness decreased with the increase in reflow time. No Ni atoms were detected in the Cu3Sn layer after 300 h of aging, indicating that the (Cu,Ni)6Sn5 phase acted as a diffusion barrier for Ni. |