Spreading Dynamics of Tin, Bismuth and Some Lead-Free Solders over Copper Substrate
The spreading of a liquid on a solid surface is very important in a number of practical applications. Many interesting physical phenomena can be observed when a small drop of a fluid spreads on a solid surface. These phenomena are related to spreading dynamics, which can be classified as spontaneous and forced wetting. In this work spreading dynamics of liquid metals and solders alloys were established to determine the mechanism of spreading. The spreading dynamics of bismuth, tin, 99.3wt%Sn-0.7wt%Cu alloy, 99.8 wt%Bi-0.2wt%Cu alloy and 60wt%Sn-40wt%Pb were studied by using sessile droplet method. Tests were carried out at a temperature range from 280oC to 350oC over a copper substrate. Results showed a discontinuous decrease of spreading velocity as a function of time. For example, spreading velocity of liquid tin at 320oC decreased from 234.86 mm/s at 0.0025 s to 4.62 mm/s at 0.0225 s, after that increased up to 9.24 mm/s at 0.025 s, then down back to 6.07 mm/s at 0.03 s, and finally reached to the end of spreading after 0.04 s.
Z.Y. Zhong, H. Saka, T.H. Kim, E.A. Holm, Y.F. Han and X.S. Xie
X. Shang et al., "Spreading Dynamics of Tin, Bismuth and Some Lead-Free Solders over Copper Substrate", Materials Science Forum, Vols. 475-479, pp. 3879-3882, 2005