A low cost bumping method for flip chip assembly and MEMS integration

In this paper we present the development of a low cost chip/wafer bumping technique for flip chip assembly and MEMS integration using a bump transfer approach. In this method, high melting temperature bumps such as copper, nickel and gold bumps are fabricated on a low cost, flexible carrier and then transferred onto the target chip/wafer/board for flip chip assembly. The aluminum pads on test chips were remetallised with electroless nickel and gold layers to facilitate the bonding of bumps to the chips using thermocompression bonding. Parallel bonding and transfer of bumps has been achieved. Bump shear test was conducted and showed that good bonding strength was achieved between the bumps and the pads.