key properties of thermal interface materials

NO.1: Thermal characteristics
1.Thermal impedance
The thermal resistance is equal to R = d / k. This equation shows that the thermal resistance is inversely proportional to the thermal conductivity k and proportional to the material thickness. In other words, the thermal conductivity of the material is a constant, and the thermal resistance is only related to the thickness of the material. The thicker the thickness, the larger the thermal resistance, and the smaller the thermal resistance; material. This will control the total thermal impedance.
2.Thermal conductivity
Thermal conductivity is a sign that determines the thermal conductivity of a thermal interface material. The larger the thermal conductivity, the better the thermal conductivity.

NO.2: Electrical characteristics
1. Breakdown voltage. The measurement of breakdown voltage is how much voltage the thermally conductive material can withstand under specific conditions. This value indicates the electrical insulation capability of the thermal interface material. This value will be affected in humid and high temperature environments, because the thermal interface material absorbs moisture in the air;
2, volume resistivity, volume resistivity is used to measure the volume electronic resistance of a unit volume of material. Volume resistivity is the ability to direct the leakage of thermal interface materials between energized components and metal heat sink components. Like the breakdown voltage, it is also affected by humidity and high temperature and also reduces the volume resistivity.

NO.3: Elastomer properties
1. Compression deformation. Compression deformation refers to the resultant force applied during deflection. When a compressive load is applied, the elastomeric material deforms, but the volume of the material remains the same. Compression deformation characteristics may change according to the geometry of the part, the deflection rate and the size of the probe;
2. Stress relaxation. When pressure is applied to the thermal interface material, a relaxation process will slowly occur after deformation, and then the pressure will be removed. This process will continue until the pressure load and the intrinsic strength of the material reach equilibrium; Compression deformation, which is the result of stress relaxation. The thermal interface material withstands compressive load for too long, and part of the deformation will become permanent deformation, which cannot be recovered after the load is reduced.