The traditionally used heat-conducting and heat-dissipating materials are mostly metals such as: Ag, Cu, A1 and metal oxides such as A12O3, MgO, BeO and other non-metallic materials such as graphite, carbon black, etc. However, with the development of industry and science and technology, people New requirements are put forward for thermally conductive materials, and it is hoped that the materials have excellent comprehensive properties. In the field of electrical and electronics, due to the rapid development of integration technology and assembly technology, the volume of electronic components and logic circuits has been reduced by thousands of times, and insulating materials with higher thermal conductivity are required to solve the problem of heat dissipation. In recent decades, the application field of polymer materials has been continuously expanded, and the use of synthetic polymer materials to replace metal materials used in traditional industries has become one of the directions of the world’s scientific research efforts.
1). What is the thermal silicone pads made of?
Using silica gel as the base material, adding certain metal oxides and various thermally conductive auxiliary materials, and then synthesizing thermally conductive silica gel sheets through a special process. The thermally conductive silicone sheet is a polymer composite thermally conductive material that uses silicone resin as the adhesive base material and is filled with thermally conductive powder to achieve thermal conductivity.
2). Common base materials and auxiliary materials made of silica gel sheets
Silicone resin (basic raw material)
1. Insulating and thermally conductive material powder: magnesium oxide, aluminum oxide, boron nitride, beryllium oxide, aluminum nitride, quartz and other silicone plasticizers
2. Flame retardant: magnesium hydroxide, aluminum hydroxide
3. Inorganic colorants (used to fill products with specific colors)
4. Cross-linking agent (makes the product slightly sticky)
5. Catalyst (process molding requirements)
Note: The thermally conductive silicone sheet plays a role in heat conduction, forming a good thermal conduction path between the heating element and the heat sink and filling the gap
Fillers include the following metallic and inorganic fillers:
1. Metal powder filler: copper powder, aluminum powder, iron powder, tin powder, nickel powder, etc.;
2. Metal oxides: aluminum oxide. bismuth oxide. beryllium oxide. magnesium oxide. zinc oxide;
3. Metal nitride: aluminum nitride. boron nitride. silicon nitride;
4. Inorganic non-metals: graphite, silicon carbide, carbon fiber, carbon nanotube, graphene, beryllium carbide, etc.
3). Thermally conductive silicone can be divided into thermally conductive silicone sheets and non-silicon silicone sheets
The insulation performance of most thermally conductive silicone sheets is determined by the insulation performance of the filler particles.
1. Thermally conductive silicone gasket
Thermally conductive silicone sheets are divided into many small categories according to the thermal conductivity of the product and the surface material, each of which has its own different characteristics
2. Non-silicon silicone gasket
Non-silicon silicone gasket is a material with high thermal conductivity, self-adhesive on both sides, and exhibits low thermal resistance and good electrical insulation properties under low compression force when used in electronic components assembly. It can work stably at -40℃~150℃. Meet the flame retardant grade requirements of UL94V0
4): the working principle of thermal conductive silicone sheet
General overview: The thermal conductivity of the thermally conductive silicone sheet depends on the interaction between the polymer and the thermally conductive filler. Different types of fillers have different thermal conductivity mechanisms
1. Thermal conduction mechanism of metal fillers
The heat conduction of metal fillers mainly depends on the movement of electrons, and the corresponding heat is transferred during the movement of electrons.
2. Thermal conduction mechanism of non-metallic fillers
The heat conduction of non-metallic fillers mainly depends on phonon heat conduction, and its thermal energy diffusion rate mainly depends on the vibration of adjacent atoms or binding groups. Including metal oxides, carbides and nitrides, etc.