Advanced flip chip bonding techniques using transferred microsolder bumps

For future high-speed and high-density OE-MCM (optoelectronic multi-chip module) packaging, a technique will be needed that can bond several high-speed photonic devices and LSIs onto an OE substrate using various heat-treatment processes and can allow control of the device´s position for optical alignment and high-density packaging. In the present work, we produce two advanced transferred microsolder bump bonding techniques for high-speed and high-density OE- MCM packaging. One uses 80% Au-Sn transferred microsolder bump bonding. This material allows module packaging using processes at various temperature because it has a higher melting temperature than 100% In and 60% Sn-Pb solder. The other technique uses multi-transferred microsolder bumps made using a repeated transfer process. It can offer accurate three-dimensional flip-chip bonding because it provides precise vertical and horizontal alignments within the errors of ±0.5 μm. These techniques will thus be very useful in developing the high-speed and high-density OE-MCM for for multi-functional boardlevel interconnection in future optical communication systems