The thermal problem of the battery module affects the safety, performance and efficacy, service life and other key factors of the battery. Too high or too low a temperature will affect the battery pack. Therefore, it is necessary to control its temperature range so that it can operate stably for a long time.
A common battery module is composed of multiple batteries. The battery pack will generate a lot of heat in the discharge mode. People install heat dissipation plates on the battery pack to guide the heat from the battery side to the heat dissipation plate side, and then take the heat away under the action of air cooling or liquid cooling, so as to achieve the effect of heat dissipation. However, there is a gap between the battery pack and the heat dissipation plate, and there is a large amount of air between the gaps, which will hinder the heat transfer efficiency, so the heat dissipation effect will be reduced and the expected effect will not be achieved.
Therefore, people will fill the thermal conductive silicon film between the heat dissipation plate and the battery pack, eliminate the air between the interfaces, and improve the heat transfer efficiency. Thermal conductive silica gel sheet is one of the commonly used traditional process thermal conductive materials. It has high thermal conductivity, low thermal resistance, insulation, cold and thermal shock resistance and other characteristics. It acts between the heat generator and the radiator, fills the gap between the interface and expels the air at the interface, reduces the contact thermal resistance and improves the thermal conductivity. Moreover, the thermal conductive silica gel sheet is soft and elastic, and can act as a shock absorber, It is very suitable for the field of power battery pack.
The thermal conductive silicone sheet uses ordinary silicone as raw material, and then needs to be made into a silicone thermal pad with very good thermal conductivity through special processes. Its main role is to play a role of heat transfer in high-temperature products.
Process flow of silica gel sheet
1. Raw material preparation
The thermal conductivity of ordinary organic silica gel is usually only about 0.2w/m · K. However, mixing thermal conductive filler in ordinary silica gel can improve its thermal conductivity. Common thermal conductive fillers include metal oxides (such as Al2O3, MgO, BeO, etc.) and metal nitrides (such as sin, AlN, BN, etc.). The thermal conductivity of the filler is not only related to the material itself, but also closely related to the particle size distribution, morphology, interface contact, and the degree of binding within the molecule of the thermally conductive filler. Generally speaking, fibrous or foil-like thermal conductive fillers have better thermal conductivity.
2. Molding and mixing
Plasticizing and mixing is a process of silica gel processing, which refers to the use of mechanical or chemical methods to reduce the molecular weight and viscosity of raw rubber to improve its plasticity and obtain appropriate fluidity to meet the needs of further processing of mixing and molding. The raw materials for the production of thermal conductive silicon films are generally destroyed by mechanical high-speed stirring. After color matching and mixing, the Milky silica gel is transformed into various colors.
3. Molding vulcanization
If you want to make a soft, elastic and tensile conductive silicon film, you need to use an organic silicone that has been vulcanized twice. Vulcanization can also be called curing. After the liquid thermal conductive silicone is heated and formed in the first stage, its crosslinking density is not enough. It is necessary to make it undergo further vulcanization reaction to increase the pull-up strength, resilience, hardness, swelling degree, density and thermal stability of the thermal conductive silicone film, which are greatly improved compared with one-time vulcanization.
If the secondary vulcanization is not carried out, the performance of the heat conductive silicone sheet produced may be affected to a certain extent, and the product with better performance will not be obtained. The product parameters after primary vulcanization are different from those after secondary vulcanization, which is also related to the actual operation process and steps.
4. Trimming and cutting
The heat-conductive silicon film after high-temperature treatment needs to be placed for a period of time to allow it to cool naturally before cutting with different sizes and specifications, instead of using other rapid cooling methods. Otherwise, the product performance of the thermal conductive silicone pad will be directly affected.
5. Finished product inspection
Among them, the main items to be tested for finished products include: thermal conductivity, temperature resistance range, volume resistivity, voltage resistance, flame retardancy, tensile strength, hardness, thickness, etc.
Thermal conductive silicone sheet tp150
Thermal conductive silicone tp150 is a product that takes into account performance and economy. It is a unique thermal conductive gasket with low oil permeability, low thermal resistance, high softness and high compliance. It can work stably at - 40 ℃ ~ 150 ℃, meeting the requirements of UL94V0 flame retardant grade.
Product features: a unique heat conductive gasket with low oil permeability, low thermal resistance, high flexibility and high compliance.
Typical application: calculator heat dissipation module, between cooling device and chassis or frame.
Thermal conductive silicone sheet tp300
Thermal conductive silicone sheet tp300 is an ultra soft material with high thermal conductivity. It shows low thermal resistance and high deformation under low pressure. It has very good caulking performance. It is recommended to use it on planes with large tolerance. In addition, tp300 is self-adhesive and does not need an additional adhesive coating that hinders heat conduction.
Product highlights: high electrical insulation, good temperature resistance, high heat dissipation performance and cost-effectiveness.
Typical applications: notebook and desktop computers, hard disk drives and DVD drives.
Thermal conductive silicone sheet tp700
Thermal conductive silicone tp700 is a material with high thermal conductivity. It is self-adhesive on both sides. When assembled with electronic components, it shows low thermal resistance and good electrical insulation characteristics under low compression force. It can work stably at - 40 ℃ ~ 150 ℃, meeting the requirements of UL94V0 flame retardant grade.
Product highlights: thermal conductivity 7.0w/mk, high thermal conductivity, ultra-low compression, high electrical insulation, good temperature resistance.
Typical applications: voltage regulation modules (VRMs); ASICs and DSPs, high-speed and large storage drivers; High calorie BGAs.