Common problems to consider when using thermal grease
2017-12-29Auther: Thermo Electronic Technology Co., Ltd

Thermal grease is thermally conductive and insulating. General desktop PC processor applications, the thermal conductivity of 3.0w-4.0w / mK on it, the higher the better. In large power MOSFET applications, through the current up to dozens of Abs to dozens of times, even a small resistance, the heat generated is very large, the design of electronic engineers will usually use a larger Volume of heatsink, some IGBT suppliers usually recommend using about 3.0w / mK of grease, especially for some IGBT devices operating current several hundred times, it is recommended to use 5.0w / mK grease. So, the use of thermal grease will appear what are the common problems? Please read the following points:
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  1. How to choose the right thermal grease / thermal conductivity thermal conductivity
    Select the appropriate thermal conductivity and application-specific, especially with the need to derive the size of the heat power, the size of the radiator, as well as the temperature difference between the two sides of the interface requirements. When the radiator size is large enough, the need to export the heat is relatively large, the use of high thermal conductivity of thermal grease and the use of low thermal conductivity of the grease compared to the interface temperature difference can have dozen to twenty degrees The difference Of course, if the radiator is not large enough, the effect will not be so noticeable.
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  2. How to evaluate the effect of thermal grease
    In the absence of professional equipment, the assessment of a thermal grease or thermal interface material is good or bad, the easiest way is to measure the interface filled with the interface thermal conductivity of the material on both sides of the temperature, if the temperature difference is large, indicating the choice of Thermal conductivity of thermal grease may not be high enough. As for how much the temperature difference is appropriate, and the application of the device operating temperature, junction temperature requirements and power have a lot of relationship .
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  3. What is the thermal grease extrusion phenomenon
    The hot and cold cycle of the electronic device is the cause of the thermal grease being squeezed out. Sandwiched between the chip and the heat sink, silicone grease is difficult to apply without a little bubble, and the thermal grease to maintain the liquid will not be cured, so that when many electronic devices on or off there will be warm temperature (temperature from low to high from High to low, such as PC), thermal expansion and contraction will change the volume of bubbles in the grease in order to heat the grease out of the gap.

       4. What is thixotropic thermal grease
      Thixotropy for thermal grease means that when an external force is applied, the flow of the thermal grease is gradually softened to show a decrease in viscosity, but once again at a standstill, the consistency increases again after      a  short period of time Recovery), that is, the changing nature of. This property of thermal grease shows up when you put it there and it does not flow, and when you apply it, it's easy. Dongguan Siu Ke Thermal Grease has good       thixotropy, which can be used in the interface for thermal conductivity will not easily be small bubbles out.

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