Thermal interface material or TIM can be defined as any material that is applied between the interfaces of two components to enhance the thermal coupling between these devices. Usually, TIM is used between a heat generating device (e.g. microprocessor, photonic integrated circuits, etc.) and a heat dissipating device (e.g. heat sink) to remove the heat from the component.
WHY TIM?
The effective transfer/removal of heat from a semiconductor device is crucial to ensure reliable operation and to enhance the lifetime of these components. Microscopic surface roughness and non-planarity of the IC/heat spreader and heat sink surfaces result in asperities between the two mating surfaces. These asperities prevent the two solid surfaces from forming a thermally perfect contact due to the poor thermal conductivity of air that exists in the gaps between two mating surfaces.
TIMs are therefore used to provide an effective heat conduction path between the solid surfaces due to their conformation (under pressure) to surface roughness and reasonably high thermal conductivity.
