Use of AuSn solder bumps in three-dimensional passive aligned packaging of LD/PD arrays on Si optical benches

Precise three-dimensional passive alignment of LD/PD arrays on Si optical benches has been achieved by means of AuSn solder bumps. A punch-and-die technique is used to fabricate the AuSn solder bumps to an extremely high accuracy (/spl plusmn/2 /spl mu/m) in bump height. A stripe-type bump bonding technique is employed to attain precise vertical alignment (/spl plusmn/1 /spl mu/m) of an LD array chip. Average LD-single-mode fiber array coupling loss was as low as -9.5/spl plusmn/0.5 dB, and while that of a PD-multimode fiber array was -0.4/spl plusmn/0.3 dB, almost as good as that with active alignment.