Thermal and Mechanical Characterization of High Power GaN Packages

摘要

The typical package available for high power GaN application has the devices directly attached onto ametal flange, which could contribute significantly to the overall thermal resistance. This paper discusses analternative approach to packaging both single and multiple devices through a heat spreader, which couldpotentially improve thermal performance and bring significant benefits to assembly in yields and cost. However,the heat spreader could also introduce significant CTE mis-match and potential concerns in reliability.Nonlinear 3D finite element analysis (FEA) was conducted to characterize the thermal performance andevaluate mechanical/reliability concerns. Thermal modeling considered single and multiple die applications, andthe results show13-15% thermal improvement with the copper heat spreader. Mechanical analysis focused on thethermal loads of the die attach and solder reflow processes. It reveals that the die attach process is more critical asshown in the higher stress due to higher thermal load, but stress/strain levels appear to be acceptable. Thus, thisalternative approach could be a viable solution.