Heat dissipation is a key problem to be solved in the application of products in the field of intelligent manufacturing, and it is a key to a heat conduction process before this. The thermal interface material often used in the design of the heat dissipation module is the thermal silicone pad, which is widely used because of its high thermal conductivity, electrical insulation and good compression performance; the thermal pads often needs to be assembled between the frame of the heat sink. It plays the role of heat conduction, buffering and shock absorption. However, in practical applications, in order to ensure that the thermal pads can be intact during assembly, that the gaps can be filled correctly, and that the thermal pad is not damaged and fallen off during use, we often need to test different thicknesses of the thermal pads, and select the appropriate thickness. thermal pads. So how thick is the thermal silicone pads? Is the thermal pads thick or thin? Does thickness affect the performance of thermal pads? CoolThermo to discuss with you!
To understand these problems, we must first understand the relationship between the thermal conductivity, thermal resistance and thickness of the thermal pads material. Through the law of Fourier equation, we can know:
K: Thermal conductivity (unit: W/m.k)
A: Contact area
d: heat transfer distance
△T: temperature difference
R: thermal resistance value
Thermal conductivity K is an inherent performance parameter of the thermal pads itself, which is used to describe the thermal conductivity of the thermal pads. This feature has nothing to do with the size, shape and thickness of the material itself, but only with the composition of the thermal pads material itself. Therefore, the thermal conductivity of similar materials is the same, and will not change due to different thicknesses.
Combining the above two formulas, you can get K=d/R. Thermal conductivity K is an inherent performance parameter of the material itself. When the value of k remains unchanged, it can be seen that the value of thermal resistance R is proportional to the thickness d of the material. That is to say, the thicker the thermal pads, the greater the thermal resistance.
According to the Fourier equation law, the relationship between the thermal conductivity, thickness and thermal resistance of the thermal pads can be summarized:
- For the same thermal pads material, the thermal conductivity is a constant value, and the thermal resistance value will change with the thickness.
- For the same thermal pads material, the thicker it is, it can be simply understood that the more paths the heat has to travel through the thermal pads material, the more time it takes and the worse the performance.
- For the thermal pads material, the selection of appropriate thermal conductivity and thickness has a great influence on the performance of the thermal pads. Choose a material with high thermal conductivity, but with a large thickness, the thermal resistance will also increase, which will also affect the performance of the thermal pads. The ideal choice is: high thermal conductivity, thin thickness, perfect contact pressure to ensure better interface contact.
All the heat of the thermal pads are conducted from one end to the other through the material, which is almost impossible to achieve. The thermal resistance value obtained by testing and calculation is actually the thermal resistance value of the thermal pads material + the thermal resistance value of the contact surface. Due to the different environment of the contact surface, the thermal resistance value measured for the same material under different conditions is also different.
The thermal conductivity of the thermal pad is a fixed value. Only the thermal resistance value changes with the thickness. The thickness of the thermal pads has a wide range of choices. CoolThermo can achieve from 0.15mm to 10mm. Shorter, the smaller the thermal resistance is, the faster the thermal conductivity is, and the better the thermal conduction effect is; on the contrary, the thicker the thermal pads thickness, the thermal resistance will increase accordingly, and the thermal conduction effect will be worse.
How thick is the thermal pads? Is the thermal conductive silicone sheet thick or thin? It is theoretically difficult to recommend what thickness of thermal pads material to customers. It is difficult to accurately calculate which thermal conductive silicone sheet is suitable for selection through some simple data. It depends more on tests and comparisons, as well as experience. The ideal effect of the test to meet the product requirements is a more suitable thermal conductive silicone sheet.
The thermal pads cannot be said that the larger the thickness, the better the performance. Only the one suitable for your own product is the best. It has to be what it is. Then the thermal conductivity is high, the thickness is thin, and the perfect contact pressure guarantees the best Interface contact is the primary choice.
Non-professional users will pay attention to the thermal conductivity of the thermal pads material; professional users will pay attention to the thermal resistance of the thermal pads material. In practical applications, customers are more concerned about thermal resistance. The difference between different test standards for thermal conductivity is quite obvious, and the data of some manufacturers is very watery.