Types of thermally conductive plastic fillers

Thermal conductive plastic is a resin material or resin composite material with a high thermal conductivity.In some working environments where materials are prone to corrosion, thermally conductive plastics extrusion line have a working life that is unmatched by metal materials. However, the thermal conductivity of the resin material itself is not ideal, and high thermal conductivity fillers need to be added to it to improve the thermal conductivity of the material.

At the end of the 20th century, foreign experts often added metal powder to resin to improve the thermal conductivity of the material.

1. Nitride

Nitride usually has the advantages of high thermal conductivity, high temperature resistance, and good electrical insulation properties. It can increase the thermal conductivity of plastics without reducing the electrical insulation properties of the material. However, its disadvantage is that the price is relatively high, which limits its wide application in plastics. The nitrides used as thermal conductive fillers mainly include boron nitride (BN), silicon nitride (Si3N4) and aluminum nitride (AlN), etc. Their thermal conductivity can reach 200~300 W/(m·K).

2. Carbide

Silicon carbide can be divided into hexagonal crystal system (α-SiC) and cubic crystal system (β-SiC). Its thermal conductivity is 80~120 W/(m·K). It is a excellent thermally conductive filler. Silicon carbide also has the advantages of high temperature resistance, high modulus and good oxidation resistance, and is used in microelectronic packaging materials. Boron carbide (B4C) is also a high-temperature resistant material with extremely high hardness and thermal conductivity. However, its high price has led to its limited use in thermally conductive plastics.

3.Oxide

Oxide fillers mainly include aluminum oxide (Al2O3), zinc oxide (ZnO), and magnesium oxide (MgO). Although their thermal conductivity is not as high as that of nitrides and carbides, it is generally between 30 and 50 W/(m·K), but also much higher than the polymer matrix, and has excellent electrical insulation properties. In particular, it has wide sources, low price, and market competitiveness. It is a commonly used filler for preparing insulating and thermally conductive plastics.

4. Metallic powder

Generally, metal powders have extremely high thermal conductivity, up to 100-400 W/(m·K), and are good thermal conductive fillers.However, since the heat transfer mode of metal-based fillers is electronic heat conduction and poor electrical insulation properties, their application in the electronic industry with strict electrical insulation requirements is limited.

5. New carbon materials

New carbon materials such as graphite, carbon nanotubes, and diamond also have extremely high thermal conductivity. The thermal conductivity of carbon nanotubes and diamond can reach more than 1000 W/(m·K).However, due to its extremely high cost, it has not been used on a large scale, and the addition of carbon fillers usually makes the color of the product black, which is limited in the application of light-colored products.