In many electronic and electrical components that require heat dissipation, in order to meet the requirements of the process, traditional fans are not used to dissipate heat, but thinner thermal pads are selected, but the thermally conductive silicone is not directly placed between the components. When the sheet is placed, it is often subjected to adhesive treatment on the basis of the thermal pads according to the requirements of the process.
Analysis of the working principle of thermal pad adhesive
The thermal pad is mainly filled in the gap between the radiator and the heat source to remove the air in the gap, so that the heat sink and the heat source can be in close contact, but not all planes are placed horizontally, and some heat sources may be caused by It is designed to be placed vertically or on an inclined plane, so there may be a possibility of slipping during use or transportation. At the same time, the plane of the heat source may be smooth and flat. Although the thermal pads are self-adhesive, the adhesiveness is low. It is also easy to be displaced by external force.
Adhesive of the thermal pad is mainly to enable the thermal pads to be firmly fixed on the plane and not easily fall off under the condition of external force, while the backing of the thermal pads needs to be coated with adhesive on its surface, but this will increase its cost, thermal resistance, so the thermal conductivity of the thermal pad will decrease, but it must be back-adhesive in order to be fixed on the surface.
In addition, there is another reason that no matter what type of components, whether it is used for a long time or affected by the environment, there will be vibration. The thermal pad will loosen and slip, causing thermal damage to the components.
Does thermal pad adhesive affect heat dissipation?
As we know from the front, after the back glue treatment is carried out in the thermal pad, it can be firmly adhered to the component. Although the gap between the thermal pad and the component connection is greatly reduced, due to the existence of the back glue, the It is impossible to make the thermal pad work normally to dissipate heat, that is to say, the adhesive backing changes the heat dissipation coefficient of the thermal pad.
According to the previous introduction to the thermal pad, we know that the higher the heat dissipation coefficient, the better the heat dissipation effect. Therefore, after using the adhesive, the actual heat dissipation efficiency will be reduced to some extent, but this It is much better than the failure to dissipate heat due to the accidental sliding of the thermal pad. Although the problem of back glue cannot be solved at present, it will not affect the use in practice.
Introduction to the advantages and disadvantages of thermal pad adhesive
Advantages: It can stick to the surface of the heat source on one side. When the radiator or the shell slides relatively during the assembly process, the thermal pads will not move and cause positional deviation, which plays a fixed role. The thermal pads adhesive is mainly because the product has no fixing device or is inconvenient to fix. The adhesive can be used to fix the radiator and stick the IC and the heat sink, and there is no need to design another fixing structure.
In addition, the adhesive can be used to fix the radiator, and there is no need to design another fixing structure, such as no locking screws, which reduces customer costs.
Disadvantages: The thermal conductivity of the thermal pads adhesive will be worse, and the thermal conductivity will be much lower. The thermal conductivity of double-sided adhesive will be worse than that of single-sided adhesive, but whether it is single-sided or double-sided adhesive, the thermal conductivity will be The impact is much lower and the thermal conductivity is worse, but the cost will increase!
How to choose thermal pads adhesive
Basically, in all equipment that needs to use thermal pads, it is inevitable to use back glue. From the previous introduction, you can also know why the thermal pads needs to be back glued, but in actual selection, not all All kinds of back glue can be used, and different equipment and different use environments have very high requirements on the back glue. For example, in notebook computers, the back glue selected is good and sticky, and cannot be used for a long time or Drying in a hot environment will greatly reduce the heat dissipation performance of the thermal pads, that is, a barrier will be formed between the thermal pads and the chip.
In general, although the thermal conductivity of the thermal pads has decreased after the adhesive is applied, its practicability has been improved, and it can better cooperate with the product to dissipate heat. Therefore, whether to add adhesive or not depends on the actual situation. choose!