Transient liquid phase (TLP) bonding for microsystem packaging applications

This paper explores the use of transient liquid phase bonding for microsystem packaging applications. Two types of bonds are demonstrated: a thin-film evaporated indium-gold bond and an electroplated nickel-tin bond. Both bonds are formed at 300°C for about 1.5 hours in a conventional wafer bonder. The wafers were heated to over 400 °C for more than an hour after bonding without any signs of bond degradation. The indium-gold bond demonstrated good electrical contact, but poor permeability performance. However, the nickel-tin bond was void free and sealed cavities with bond ring widths as little as 50 μm. The cross section of the nickel-tin TLP bond was analyzed with EDAX software to verify the formation of intermetallic compounds.