What Is a Thermal Pad? What Is Thermal Pad Made Of?

What Is a Thermal Pad? What Is Thermal Pad Made Of?

Thermal pads are high-performance gap-filled thermally conductive materials, which are mainly used for the transfer interface between electronic devices and heat sinks or product casings; traditionally used heat-dissipating and thermally conductive materials are mostly metals, such as Ag, Cu, Al, and metal oxides, such as Al2O3, MgO, BeO and other non-metallic materials, such as graphite, carbon black, etc.; but with the development of industry and science and technology, people have put forward new requirements for thermal conductive materials, hoping 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. 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, and thermal conductive gaskets have emerged as the times require.

What material is the thermal pad made of?

The thermal pad is based on silica gel, adding certain metal oxides and various thermal auxiliary materials, and then synthesizing the thermal pad through a special process. The thermal pad is a polymer composite thermal conductive material that uses silicone resin as the adhesive base material and is filled with thermal conductive powder to achieve thermal conductivity.

Thermal conductive gasket making base 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 (make the product slightly sticky)
  5. Catalyst (process molding requirements)
    Note: The thermal pad plays the role of heat conduction, forms a good thermal conduction path between the heating element and the heat sink and can fill the gap.

Thermal gasket filler composition

  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 nitrides: aluminum nitride, boron nitride, silicon nitride;
  4. Inorganic non-metals: graphite, silicon carbide, carbon fiber, carbon nanotubes, graphene, beryllium carbide, etc.

Process principle

The thermal conductivity of thermal gaskets depends on the interaction of the polymer with the thermally conductive filler. Different types of fillers have different thermal conductivity mechanisms.
The heat conduction mechanism of metal fillers, the heat conduction of metal fillers is mainly carried out by the movement of electrons, and the corresponding heat is transferred in the process of electron movement;
The thermal conduction mechanism of non-metallic fillers, the thermal 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. Including metal oxides, carbides and nitrides.

With the advent of the 5G era, electronic products are developing towards functional integration. There are more and more components on the circuit board, and the power of electronic products is getting higher and higher. The thermal conductivity of thermal pads is increasingly required. The commercial application of thermal pads also has broader development prospects. This requires relevant thermal pad manufacturers to continuously develop thermal pad materials with better performance.

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