Characterization of individualized assembly for BFL-compensated FAC on bottom tab modules

Uncertain glue gaps lead to challenging assembly tasks in respect to shrinkage control. With decreasing back-focal lengths (BFL) in collimators, the tolerance window for correct alignments decreases as well and forces manufactures to find novel approaches to realize the bonding process. We present performance characteristics of an automated assembly cell for individualized FAC on bottom tab modules. BFL-compensated collimators allow minimizing the critical adhesive gap between substrate and diode laser. This provides optimal control over shrinkage, as well as thermal aspects of the bonding properties. We will focus on the active alignment, which provides the individual focus distance, as well as the relative image processing necessary to assemble both components with ±1 µm precision. Our machine concept and measurement equipment is suitable as stand-alone process for optic manufacturers, as well as integrated part in the final application assembly. In last year’s publication (SPIE 10086), we presented the general concept and can now support our approach with more details from our operating data. With minimized adhesive gaps, the robustness of the proposed concept and a precise characterization of its process window is key, as minimal variations lead to rejects and cause high costs during the final application assembly. Besides classic properties, many more characteristics, e.g. smile behavior of the optic module, are potential optimization factors to increase beam quality. Characterization data from both optic and laser allow applying tolerance matching, where alignment is physically constraint. Performance wise, we will discuss the repeatability, achievable precision and the implications on process time.