We measured the thermal conductivity of a thermal pad using steady-state method.

A thermal pad is a type of thermal interface material used for heat dissipation in CPUs and power devices. Due to its flexibility and relatively high thermal conductivity, it reduces contact thermal resistance by filling the irregularities between the heat sink and the device.

In this study, we measured a commercially available thermal pad with a specification of 1.5 W/mK. Additionally, it is of the soft type known as a soft type. The measurement apparatus used was our steady-state thermal conductivity measurement device, SS-H40.

Thermal Pad Specifications:
Size: 40mm x 40mm x 5mm
Thermal conductivity: 1.5 W/m-K
Heat resistance temperature: 50~200 (°C)

Figure 1: Thermal Pad

First, we measured the sample by varying the load.
Measurement conditions:
Sample temperature: 30°C
Pressure: 200N, 400N, 600N, 800N


As the load increased, the thermal conductivity increased and became nearly constant at 600N. If the pressure is insufficient, the material and thermal pad may not adhere sufficiently, resulting in increased contact thermal resistance and decreased thermal conductivity. However, with sufficient pressure, adhesion occurs, reducing contact thermal resistance and increasing thermal conductivity. (This can be interpreted as the thermal conductivity including contact thermal resistance. Therefore, terms like "effective thermal conductivity" are sometimes recommended, as it is not the inherent thermal conductivity of the material.)

Next, we measured the sample by varying the temperature.
Measurement conditions:
Sample temperature: 30°C, 40°C, 50°C
Pressure: 600N


As the sample temperature increased, the thermal conductivity decreased. The thermal conductivity decreased by 3.3% between sample temperatures of 30°C and 40°C, but only by 0.5% between 40°C and 50°C. Since the thermal conductivity of the material also changes with temperature, this could potentially influence the results.

At Betel, we conduct thermal conductivity measurements and sell various thermal conductivity measurement devices. For inquiries, please contact us through the web form.