The Study of Effects to the Thermo-Mechanical Performance of the First Level Thermal Interface Materials

The booming growth of flexible and stretchable electronic devices with increasing power density calls for novel highly efficient thermal interface materials (TIMs) with versatile functions, such as high deformability and excellent resilience. Soft polymer composites such as silicone gap pad are expected to reduce the contact resistance and thermal impedance, but the huge mismatch of the thermal expansion coefficient between the heat sink and the microelectronic chip and stretching behavior make them under stress, especially in the way of tensile stress in stretchable electronic devices. So far, few researchers have reported study about the effect of tensile behavior on the properties of TIMs. In this work, DMA (dynamic mechanical analysis) was used to characterize the resilience, creep and stress relaxation characteristics of silicones gap padsIt was found that as the strain increases, the rebound ratio increases at the first and then decreases, reaching the maximum at 20% of its maximum stretching length. When the term of time is considered, the plasticity of the tensile behavior is not linearly related to time but decelerates as time increases. In five cycles of loading-unloading, the increase in stretch length can enhance the degree of plastic deformation significantly, while the stretch rate has no correspond with it. This research can provide important guidance for the application of TIMs in stretchable electronic devices industry.