Industry dynamic

How to choose a suitable thermal pad


Thermal pads are high-performance gap-filling thermally conductive materials, mainly used for the transfer interface between electronic equipment and heat sinks or product shells. They have good viscosity, flexibility, good compression properties and excellent thermal conductivity, making them suitable for use It can completely discharge the air between the electronic components and the heat sink to achieve full contact, conduct heat from the separation device or the entire PCB to the metal shell or the diffusion plate, thereby improving the service efficiency and life of the heating electronic components.


Selection of base material

There are two kinds of polymer materials for the base material of common thermal pads: silicone and non-silicon.

The most widely used thermal pad is the silicone thermal pad, which inherits the good temperature resistance (-50°C~200°C) and chemical corrosion resistance of silicone; but it will release a small amount of silicone oil during long-term use. Molecules, in some occasions, such as optical equipment, high-sensitivity probes, high-definition cameras and other high-end electronic and electrical industries, may be limited in use.

On the contrary, the non-silicon thermal pad (phase change material) solves the problem of the release of small molecules of silicone oil from the silicone thermal pad, avoids atomization of the laser probe, and does not affect components, thereby ensuring the stability of precision electronic products.

The choice of thermal conductivity

The choice of thermal conductivity needs to be determined in combination with the application environment and requirements.

1: Look at the heat generation of electronic components. The higher the power, the greater the heat generation, and the greater the heat that needs to be dissipated, so the higher the thermal conductivity of the thermal pad is required.

2: Look at the design gap thickness, the expected temperature reduction and the heat transfer area. Estimate the area thermal resistance of electronic components according to the Fourier equation, and then combine the thickness-thermal resistance curves of gaskets with different thermal conductivity to determine the thermal conductivity of the required product.

Choice of thickness

The thickness of the thermal pad is generally selected according to the design gap width of electronic components. It is generally recommended to compress the thickness by 20%-50% to be close to the gap thickness. For example, if the thickness of the gap is 1.5mm, a 2.0mm product can be recommended, because the 2.0mm thermal pad is compressed by 25% to be the same as the thickness of the gap. A product of this thickness can ensure that the gap is filled without causing excessive stress.

The hardness of the product has a great influence on the compression performance. Under the premise of ensuring the physical strength, it is recommended to choose products with low hardness. In addition to the reason of smaller stress, the interface affinity of the gasket with low hardness is also better, and the interface thermal resistance is lower.


TENSAN thermal pad products provide a variety of formulation options. Both sides have natural stickiness, which can be closely attached to the device, which can reduce the production cost of the heat sink while reducing the thermal resistance.

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