Views: 0 Author: Site Editor Publish Time: 2021-04-21 Origin: Site
Traditional thermal conductivity materials are mostly metals such as Ag, Cu,A1, metal oxides such as A12O3, MgO, BeO, and other non-metallic materials such as graphite, carbon black,Si3N4,A1N. With the development of industrial production and science and technology, people put forward new requirements for thermal conductive materials, hoping that the materials have excellent comprehensive properties. For example, due to the rapid development of integration technology and assembly technology in the electrical and electronic field, the volume of electronic components and logic circuits is reduced tens of thousands of times, which requires insulation materials with high thermal conductivity. In recent decades, the application of polymer materials has been expanding, and replacing various materials used in traditional industry with synthetic polymer materials, especially metal materials, has become one of the directions of scientific research efforts in the world.
What is the thermal conductivity silica gel sheet
Thermal conductive silica gel sheet is a kind of thermal conductive medium material synthesized by special process with silica gel as the base material and metal oxides and other auxiliary materials. Thermal conductivity silicone rubber is a polymer composite material with silicone resin as bonding material and thermal conductivity powder filled to achieve the purpose of thermal conductivity.
Commonly used thermal conductive silica gel matrix materials and fillers
Silicone resin (base material)
1. Insulation and thermal conductivity filler: alumina, magnesium oxide, boron nitride, aluminum nitride, beryllium oxide, quartz and other silicone plasticizer
2. Flame retardant: magnesium hydroxide, aluminum hydroxide
3. Inorganic colorants (color differentiation)
4. Crosslinking agent (adhesive property requirements)
5. Catalyst (Process Forming Requirements)
Note: Thermal conductive silica gel sheet plays the role of thermal conduction, forming a good thermal conduction path between the heating element and the heat dissipation device, and forming the heat dissipation module together with the heat sink, structural fixing parts (fans), etc.
Fillers include the following metallic and inorganic fillers:
1. Metal powder filler: copper powder. Aluminium powder. Iron powder. Tin powder. Nickel powder etc.
2. Metal oxide: alumina. Bismuth oxide. Beryllium oxide. Magnesium oxide; zinc oxide;
3. Metal nitride: aluminum nitride. Boron nitride. Silicon nitride;
4. Inorganic nonmetal: graphite. Silicon carbide. Carbon fiber. Carbon nanotubes. Graphene. Beryllium carbide etc.
Classification of thermal conductivity silica gel
Thermal conductive silica gel can be divided into: thermal conductive silica gel gasket and non-silicon silica gel gasket. The electrical insulation performance of the vast majority of thermal conductive silica gel is ultimately determined by the insulation performance of filler particles.
1. Thermal conductive silica gel gasket
Thermal conductive silica gel gaskets are divided into many small categories, each of which has its own different characteristics.
2. Non-silicon silicone gasket
Non-silicon silicone gasket is a kind of material with high thermal conductivity, double-sided self-adhesive, which shows low thermal resistance and good electrical insulation characteristics under low compression force when used in the assembly of electronic components. It works stably at -40℃~150℃. Meet the flame retardant grade of UL94V0.
Thermal conductivity mechanism of thermal conductivity silica gel
The thermal conductivity of the thermal conductive silica gel depends on the interaction between the polymer and the thermal conductive filler. Different kinds of fillers have different thermal conductivity mechanisms.
1, the heat conduction mechanism of metal filler
The heat conduction of metal filler is mainly carried out by the movement of electrons, which is accompanied by the transfer of heat.
2, the heat conduction mechanism of non-metallic fillers
The heat conduction of nonmetallic fillers mainly depends on phonon heat conduction, and the thermal energy diffusion rate mainly depends on the vibration of adjacent atoms or bonded groups. Includes metal oxides, metal nitrides and carbides.