Evaluation of an advanced thermal transfer adhesive for thermal management applications

This paper describes the thermal evaluation of a die bonding adhesive that consists of high thermal conductivity carbon fibers orientated through the thickness of a thin epoxy resin film. A major challenge in the development of the adhesive was faced in identifying a test that would predict the comparative thermal resistance (Θ_JC) performance of the adhesive in an electronic package. The test method used during the development of the adhesive failed to predict this performance. All tests available at the time required a specimen that was much thicker than a typical die bond. This appears to have led to underestimating the loss of performance at the interfaces, causing large errors in predicting package thermal resistance. A major cause of interface thermal resistance was identified using a scanning thermal imaging microscope. An adhesive was finally developed that corrected the interface problem. This adhesive was used to die bond test packages that demonstrated a lower Θ_JC than identically tested solder controls