The wetting characteristics of molten Ag–Cu–Au on Cu substrates: a molecular dynamics study
Ag–Cu–Au ternary alloys are promising solder materials for wire bonding. Limited experimental studies on Ag–Cu–Au materials can be found due to the high cost of gold. In this study, face-centered-cubic Cu(100), Cu(111), and Cu(110) substrates wetted by molten Ag45Cu42Au13 were investigated via molecular dynamics (MD). As demonstrated by melting simulation results, the Ag45Cu42Au13 alloy has a lower melting temperature compared to the eutectic alloy, Ag60Cu40. MD methods were also used to investigate the dissolutive characteristics of Ag45Cu42Au13/Cu wetting. Density profiles and contact angles show an increase in wettability in the Ag45Cu42Au13/Cu(100) wetting system. For molten Ag60Cu40 and Ag45Cu42Au13 the spreading behavior on Cu(100) shows a promoted tendency, which contrasts with both Cu(111) and Cu(110). Solid–liquid adhesion is indicative of the comparative spreading degrees. The contact angles and PMF analysis of wetting behaviors on rough and smooth Cu substrates illustrate that solid–liquid adhesion in Wenzel states is stronger than in Cassie wetting states.