Heat Sink Solutions：Heat Dissipation Path and Development Route of Thermal Interface Materials
Thermal Interface Materials (TIMs)
Thermal Interface Materials (TIMs) collectively refer to materials applied between heat-dissipating components and heat-generating components to reduce contact thermal resistance. Due to manufacturing tolerances and surface roughness, tiny air gaps typically exist between components. These gaps contain air, a poor thermal conductor with a thermal conductivity of only 0.026 W/(m·K) at room temperature, leading to significant contact thermal resistance. TIMs are therefore used to fill these gaps, expel air, provide better heat conduction paths, reduce interfacial thermal resistance, and enhance heat dissipation efficiency. Chips are bonded to heat sinks via TIMs, which play a critical role in both remote cooling and near-chip cooling. Current research on TIMs proceeds in parallel across multiple pathways, with common materials primarily divided into two categories: polymers and metals.
Currently, there are four main categories of thermal interface materials:
(1) Thermal Potting Adhesives: Used for overall encapsulation of modules.
(2) Thermal Grease (Thermal Paste): A paste-like material with certain fluidity or viscosity, used to fill tiny gaps. For example, it is applied between the CPU and heat sink, or between the heat-generating stack and casing, to squeeze out air and form a heat dissipation channel.
(3) Thermal Pad: A flexible and compressible elastic material that can well conform to irregular contact surfaces under certain pressure, filling gaps between solids without contaminating components. It is used in control motherboards of electronic and electrical products, LED heat dissipation, internal/external padding of motors, lithium battery thermal management, etc.
(4) Thermal Phase Change Materials (PCMs): Solid at room temperature and melt into liquid at a certain temperature after absorbing heat from power devices. They can thus well wet solid interfaces to reduce thermal resistance. They not only absorb heat but also have good heat transfer properties, overcoming the shortcomings of thermal grease and thermal pads—solving the difficulty of applying thermal grease and improving the poor thermal conductivity of thermal pads caused by thickness and interfacial thermal resistance.
