Analysis of Ni-coating's influence on wetting of Ag solder

Ni-coating's influence on the wetting progress in metal-ceramic bonding was analysed in this paper. Firstly Ag's contact angle was measured through high-temperature experiments, which turned out to be 100° and 25° on non-coated and Ni-coated ceramic substrates, respectively. Then a mathematical model was originally built up to catch the phase interface's motion on different substrates, considering fluid dynamics, melting and solidification, surface tension and liquid-solid heat transfer. Results indicated that Ni-coating affected the angle α directly and could reduce abnormity of joint structure through enhancing Ag solder's wettability on ceramic.