Silicon motherboards for multichannel optical modules

A novel method of a fluxless, high precision, and reliable Au/Au thermo compression flip chip bonding process for optoelectronic devices has been developed. The main technologies for the manufacturing of multichannel optical modules are based on the height control within 0.5 mu m of electroplated Au bumps on silicon motherboards in the close environment of v-grooves, the flip chip bonding applying low pressure at temperatures below 300 degrees C, and reproducible passive fiber array alignment with high coupling efficiencies. A coupling loss of 8.5 dB has been achieved, which is very close to the active alignment result of 8.1 dB. The reliability of flip chip bonded laser and photo diodes has been investigated by aging and temperature cycling tests, where no shift of the threshold current occurred, the coupling efficiency did not vary and the dark current showed no degradation. The RF performance of the electrical interconnection on the silicon motherboard has been analyzed and a transmission experiment at 622 Mb/s has been done successfully.