Thermal conductive grease is a compound that is typically electrically insulating and thermally conducting, i.e. the heat transfer can occur through such compounds. These are most commonly employed as an interface material between the source of heat and heat sinks. Thermal conductive grease is known by several alternative names such as heat paste, thermal compound, thermal interface material (TIM), heat sink compound, thermal paste, or thermal gel. The basic function of thermal conductive grease is to remove air spaces or gaps from the interface area, which play the role of thermal insulators, and facilitate maximize heat transfer.
Thermal conductive greases do not provide mechanical strength to the bonding between heat sink and source of heat, unlike thermal adhesives. External mechanical mechanisms that creates the pressure between the two are required in order to spread the thermal conductive grease onto the heat source. Thermal conductive grease comprise a polymerizable liquid matrix and thermally conductive filler. Thermally conductive fillers also are typically electrically insulating. Most commonly used matrix materials include silicone, acrylates, epoxies, urethanes, solvent-based systems, and hot-melt adhesives, while aluminum oxide, aluminum nitride, zinc oxide, and boron nitride are commonly used fillers. Among these fillers, usage of aluminum nitride is increasing.
Electronic surfaces are never smooth. Microscopic blemishes are present on any surface, which reduce the heat flow and increase contact resistance. These gaps or roughness of the surface inhibit effective heat transfer, which can potentially lead to device failure.
Key attributes that ensure good performance of thermally conductive grease are its thermal conductivity and resistance, bond line thickness, processing ability, and re-workability. Thermally conductive grease is applied in a wide array of industrial applications including power components and supplies, broadcasting equipment, ignition modules, computer equipments, audio amplifiers, power resistors, semi-conductor mounting devices, transistor diodes, thermal joints, and ballast heat transfer mediums.