Effect of solder joint integrity on the thermal performance of a TEC for a 980 nm pump laser module

Abstract

PurposeThe purpose of this paper is to evaluate the effect of solder wettability on the thermal performance of a thermo‐electric cooler (TEC) of a 980 nm pump laser module.Design/methodology/approachIn this paper, TEC thermal performance has been evaluated using a heat pump test. The results were compared with scanning acoustic microscopy (C‐SAM) results in order to have a better understanding of the thermal behaviour of the TEC. In the C‐SAM experiments, images were taken at the interfaces between the housing and TEC, as well as at the interfaces between the chip‐on‐carrier (CoC) and TEC.FindingsThe heat pump test results indicate a strong correlation with the C‐SAM test results. The C‐SAM observations show good solder joint at the interface between the TEC and housing in the case of the device that yielded a good heat pump test result (11.5°C) and poor solder joints (gross de‐lamination) at the interface between the TEC and housing in the case of the device that yielded a poor heat pump test result (24.4°C). The C‐SAM observations did not show much difference at the interface between the CoC and TEC. The results from this study were used to qualify the post‐vacuum soldered laser pump devices at JDS Uniphase, Plymouth, UK.Originality/valueThe findings presented in this paper indicate that the level of solder wettability at the interfaces between the piece parts impacts the thermal performance of the TEC.