Submicron Bonding Technology with Passive Alignment for Optical Modules.

In the field of optical module assemblies, there is a demand for the passive alignment method, which is considered to contribute both to the cost reduction and the throughput enhancement. Although the optical modules require submicron level bonding accuracy, the conventional bonders can offer no better than ±5μm level accuracy.In this paper, upgrading technologies for passive alignment bonder are reported, i.e. enhanced recognition accuracy of fiducial marks which are placedon the electrode surfaces of LD chips and silicon substrate respectively, anti-vibration structures, and anti-thermal expansion solutions. On the third issue, particularly, a new calibration method has been developed to compensate the thermal expansion that causes 1μm positional shifting at 1°C temperature change in the atmosphere or of the machine. Verification of test results on mounting accuracy is also reported.