Highly Thermal Conductive and Electrically Insulated Graphene Based Thermal Interface Material with Long-Term Reliability

Thermal management in high power devices are becoming more and more challenging due to the high density packaging as well as dramatically increased transistor integration. The conventional TIMs that are widely used in the microelectronic industry today are experiencing more and more stress due to their limited thermal performance and poor reliability. Composed by particle laden polymer matrix, conventional TIMs have thermal conductivity (K) values in the range of 1-5 W/mK, and such values can be even lower for electrically insulated TIMs. Conventional TIMs also suffer from severe pump-out and dry-out failures, which brought great threat to the performance and lifetime of the electronic devices. Here, we address these problems by utilizing a highly thermally conductive, electrically insulated and reliable graphene enhanced TIMs (I-GTs). Composed by verticalaligned graphene layers, I-GTs provide a direct heat pathway from top to bottom, which enables superfast heat dissipation at through-plane direction. The highest bulk thermal conductivity of the conductive body at the through-plane direction is over 1000 W/mK, which is 100 times higher than conventional TIMs. I-GT also possesses good flexibility and can be easily compressed over 100% at Z direction upon small applied pressures. Therefore, fully contact between two surfaces can be achieved by using I-GT as gap fillers. The minimum thermal resistance measured for I-GTs reaches about 30 Kmm2/W, which is much lower than most of the conventional TIMs. To ensure fully electrical insulation, a smooth and soft adhesive layer with a thickness of few microns was coated on the surface of I-GT. The breakdown voltage of IGT reaches up to 950 V. Thermal cycling test shows the highly stable nature of I-GT. The good compressibility and elasticity of I-GT ensures continued proper TIM contact with substrates, which counteracts the effect of internal stress induced by the mismatch of coefficient of thermal expansion (CTE) during temperature cycling. In addition, the I-GT has the advantages of low density and good maintainability. The resulting I-GTs thus offers new solutions for addressing thermal management issues in high power electronics and other systems with small form-factor.