Thermally conductive gaskets are used to fill cooling devices, communication hardware, automotive control units, LED lighting equipment, etc., by generating a certain compression to bridge the gap to achieve good thermal conductivity, and the hardness of the thermally conductive gasket will affect the requirements of the product. Compression performance of the product has a certain impact, and its parameters are very important. About the hardness of the thermal pad, I will give you a brief introduction.
1. What is the concept of hardness?
Hardness is a mechanical performance index that various mechanical parts and tools must have. It is used to characterize the hardness of the material and refers to the ability of the material to resist local deformation, especially plastic deformation, indentation or scratches.
2.What is the hardness of the thermal pad?
As different test methods are specified, there are different hardness standards. Various hardness standards have different mechanical meanings and cannot be directly converted to each other, but they can be compared through experiments. Common hardness is classified according to the test method: scratch hardness, indentation hardness, rebound hardness. According to the specific hardness name classification: Rockwell hardness, Brinell hardness, Leeb hardness, Shore hardness and so on.
According to the standard ASTM D2240 "Standard Test Method for Testing the Hardness of Rubber with Hardness Tester", the thermal pad uses Shore hardness to express its hardness. The corresponding measuring instrument of Shore hardness is Shore hardness tester, which is mainly divided into three types: Type A, Type C and Type 00. The measurement principle is exactly the same, the difference is that the size of the stylus, especially the tip diameter, is different, type 00 is the largest and type A is the smallest. The Shore A hardness tester is suitable for measuring harder thermally conductive gaskets; the Shore 00 hardness tester is suitable for measuring softer thermally conductive gaskets.
Shore hardness belongs to indentation hardness. The test method is to insert the material to be tested with a Shore hardness tester. The pointer on the dial is connected to a needle through a spring, and the needle is pierced into the surface of the object to be tested. The value displayed on the dial is the hardness. value.
3. Is the hardness of the thermal pad high or low?
The lower the hardness of the thermal pad, the softer the product and the higher the compression rate, which is suitable for use in low-stress environments. Conversely, the higher the hardness of the thermal pad, the harder the product and the lower the compression rate. Under the same application conditions, products with low hardness have higher compressibility, shorter heat conduction path, shorter heat transfer time, and better heat conduction effect than products with higher hardness.
However, it is not that the hardness is about low, and the thermal pad has a certain hardness so that it is not easy to deform. Generally speaking, thermally conductive gaskets with higher hardness have better mechanical properties. In the application, it is necessary to select a thermally conductive gasket with appropriate hardness according to the actual situation.