Effect of temperature and coatings on the wettability of Sn- Zn-Ga-Nd lead-free solder

The wetting time and wetting force of Sn-Zn- Ga-Nd lead-free solder on Sn,SnBi,Au/Ni coatings under different temperatures were measured,and the effect of soldering temperature on the wettability of solders on different coatings was investigated. The results indicate that with the increase of temperature, the wetting time reduced and the wetting force increased evidently. At 240℃,the wetting time for three coatings all met the needs of IPC standard in which the wetting timet₀ ≤ 1 s at wave soldering. On the other hand,the wettability of the solder was better on Sn/Cu and SnBi/Cu substrates than on Au/Ni/Cu substrate.