PRODUCTION PROCESS OF THERMAL CONDUCTIVE SILICON PAD

The production process of thermal conductive silica gel sheet mainly includes: raw material preparation → plastic refining, mixing → molding and vulcanization → trimming and cutting → inspection, etc.

1. Raw material preparation 

The thermal conductivity of ordinary organic silica gel is only about 0.2w/m · K. However, the thermal conductivity of silica gel can be improved by mixing thermal conductive fillers. Commonly used thermal conductive fillers include metal oxides (such as Al2O3, MgO, BeO, etc.), metal nitrides (such as sin, AlN, BN, etc.). The thermal conductivity of fillers is not only related to the material itself, but also closely related to the particle size distribution, morphology, interface contact, and the degree of internal binding of molecules. Generally speaking, the heat conduction effect of fibrous or foil sheet heat conduction filler is better.

2. Molding and mixing 

Plasticizing and mixing is a process of silica gel processing, which means to use mechanical or chemical methods to reduce the molecular weight and viscosity of raw rubber to improve its plasticity and obtain appropriate fluidity, so as to meet the needs of further processing of mixing and molding. The raw materials for making thermal conductive silicon film are generally damaged by mechanical high-speed stirring. After color mixing, the opalescent silica gel is used to change the flakes of various colors.

3. Molding vulcanization

If you want to make a soft, elastic and tensile heat conductive silicone sheet, you need to use organic silicone that has been subjected to secondary vulcanization. Vulcanization can actually be called curing. After the heat-conducting silicone liquid is heated and molded in the first stage, its cross-linking density is not enough. It needs further vulcanization to increase the tensile strength, resilience, hardness, swelling degree, density, and thermal stability of the thermally conductive silicone sheet. Vulcanization has been greatly improved. If the secondary vulcanization is not carried out, the performance of the thermally conductive silicone sheet produced may be affected to a certain extent, and products with better performance may not be obtained. The product parameters after the first vulcanization are different from the parameters of the second vulcanization, which is also related to the actual operation process and steps.

4. Trimming and cutting

The heat-conducting silicone pad after high-temperature treatment needs to be placed for a period of time to allow it to be naturally cooled and then cut in different sizes and specifications, rather than using other rapid cooling methods. Otherwise, it will directly affect the performance of the thermal conductive silicone pad.

5. Finished product testing

The main items to be tested for finished products include: thermal conductivity, temperature range, volume resistivity, voltage resistance, flame resistance, tensile strength, hardness, thickness, etc.