Thermal Interface Materials
Transferring heat from the CPU to the heat sink is challenging, particularly when the power dissipation inside the processor is large. This is because each material and each interface between different materials impedes the flow of heat to some extent. The interfaces between materials can be particularly challenging to engineer because microscopically one needs good contact between the materials. Most materials have some degree of microscopic surface roughness, which prevents materials from achieving perfect contact everywhere and leaves small microscopic air gaps in between. To mitigate this issue, one can use a compliant thermal interface material (TIM) to fill the air gaps with a more thermally conductive material, ultimately serving to lower the overall heat flow impedance. Here the challenge is to develop materials that both have high thermal conductivity, yet are also compliant and can fill the microscopic gaps between the peaks and valleys of the rough surfaces of each material. The ASE group works towards better understanding of the physics of thermal transport at small scales enabling the development of new and improved solutions to the problem of heat dissipation in microelectronics packages.