Microelectronic interconnections require advanced joining techniques. Direct metal bonding methods, which include thercomsonic and thermocompression bonding, offer remarkable advantages over soldering and adhesives joining. These processes are reviewed in this paper. The progress made in this area is outlined. Some work concerned with the bonding modeling is also presented. This model is based on the joint interface mechanics resulting from compression. Both bump and substrate deformation are taken into account. The improved understanding of the relationship between the deformation and bonding formation may provide more accurate joint evaluation criterion. / Singapore-MIT Alliance (SMA)