Multiple-chip precise self-aligned assembly for hybrid integrated optical modules using Au-Sn solder bumps

We have developed a novel three-dimensional high precision self-aligned assembly using stripe-type Au-Sn solder bumps and a micro-press solder bump formation method. This produces a high bonding precision of 1 μm for optical device assembly in both lateral and vertical directions without the need for time-consuming optical axes alignment. Furthermore, we tested a hybrid integrated 4×4 optical matrix switch, in which multiple SSC-SOAG arrays were simultaneously positioned and optical fibers were passively positioned on a silica based PLC platform using this technology. Four optical chips and seven wiring chips are assembled on a planar lightwave circuit (PLC) platform. The insertion loss for each of these paths at an injection current of 40 mA was within a range of 9±4 dB. The average extinction ratio was 40 dB. This self-aligned assembly technology was shown to be useful for building hybrid-integrated multichannel optical network components