Stress Minimization During Deflection of Thermally Conductive Gap Pads

Thermal pads are essential to providing heat transfer pathways through electronic assemblies. However upon deflection they cause stress as a result of the pads' inherent resistance to deformation. In this work it was found that this stress can be controlled by proper optimization of the physical characteristics of the pad, the assembly, and the conditions under which the thermal pad is deflected during the assembly process. Stress-strain measurements were compared for several sets of assembly conditions to determine the extent which they affected the stress levels reached during the test. Properties and conditions were then optimized to minimize stress during deflection in a simulated application. Results show that stress can be controlled by modifying the assembly process and to take advantage of the stress relaxation properties of the pad and designing to allow unimpeded lateral movement of the pad.