What Are Thermally Conductive Plastics? A Producer's Explainer
A Professional Producer of Thermally Conductive Plastics — Pulas Web Interviews Mr. Tang Jihua, General Manager of RenJie Plastics
Q1: What are thermally conductive materials?
Pulas Web: Hello, Mr. Tang. We hear your company has developed a thermally conductive material. Could you tell us what a thermally conductive material is?
Mr. Tang: Thermally conductive materials are plastic composites made by adding thermally conductive metal oxides, graphite fibers or carbon fibers to ordinary plastics to improve their thermal conductivity. Thermal performance is mainly measured by thermal conductivity (unit: W/(m·K)).
Thermally conductive plastics fall into two broad categories: electrically conductive thermally conductive plastics and electrically insulating thermally conductive plastics.
Their main components are a base material and fillers:
- Base materials: PPS, PA6/PA66, LCP, TPE, PC, PP, PPA, PEEK, and others;
- Fillers: AlN, SiC, Al2O3, graphite, fibrous high-thermal-conductivity carbon powder, flake-shaped high-thermal-conductivity carbon powder, and others.
There are three main types of thermally conductive filler: carbon materials, inorganic thermally conductive particles, and metal particles. Given the cost and insulation requirements of these plastics, inorganic thermally conductive particles are almost always chosen. Among them, aluminum oxide, magnesium oxide and zinc oxide are the most widely used because they are relatively inexpensive and make it easy to adjust the cost and whiteness of the finished plastic. Other high-thermal-conductivity fillers are of course used to meet higher thermal requirements, at a cost that steps up accordingly.
The main differences among these three oxides are:
| Filler | Thermal conductivity | Loading behaviour | Overall assessment |
|---|---|---|---|
| Magnesium oxide (MgO) | Relatively high | Thickens easily — whether the loading can be raised is a problem | Good conductivity, limited loading |
| Aluminum oxide (Al2O3, flake) | Moderate | After modification, high loadings are easy to reach | The most balanced option; high loading after modification |
| Zinc oxide (ZnO) | The lowest | Relatively hard to fill in large amounts | Limited in both conductivity and loading |
Below are pellets of two thermally conductive materials we have developed: the first is thermally conductive PP, and the second is thermally conductive nylon.
Q2: What are the characteristics of these two materials?
Pulas Web: Mr. Tang, what characteristics do these two materials have?
Mr. Tang: Thermally conductive plastics not only have the heat-transfer performance of metals and ceramics, but also retain the other advantages of ordinary plastics in terms of design, performance and cost. Polymers or plastics are, in terms of their basic properties, heat-blocking materials. Yet injection-moldable thermally conductive plastics already exist, with thermal conductivity 100 times that of the base resin.
Thermally conductive plastics are made by compounding highly thermally conductive reinforcing materials into engineering plastics or commodity plastics. Their advantages are as follows:
A. Even heat dissipation — no hot spots; B. Less deformation of parts caused by high temperatures; C. Improved mechanical properties (such as strength and stiffness); D. Low weight (40%–50% lighter than aluminum), which reduces vibration on the assembly and improves performance stability; E. A choice of base resins, such as PA, PPS, PC and PBT — or lower-cost base resins such as PP, HIPS and ABS; F. Easy to process: standard plastic molding processes can be used, suitable for high-volume production, with no secondary processing required; G. Low coefficient of thermal expansion; H. Low molding shrinkage; I. Low operating temperature, extending the average service life of components and assemblies; J. Greater design freedom.
Q3: Where are thermally conductive materials mainly used?
Pulas Web: That was a very detailed answer, Mr. Tang — clearly you know thermally conductive plastics deeply. One last question: where are thermally conductive materials mainly applied? Could you tell us?
Mr. Tang: The main application fields of thermally conductive materials include LED lighting, automotive, heating/cooling/refrigeration, transformer bobbins and other electronics fields.
Shenzhen RenJie Plastic Materials Co., Ltd. is a well-known specialized manufacturer of thermally conductive plastics in China and holds a leading domestic position in the development and production of thermally conductive materials. Sales hotline: 18681139818; Contact: Tang Jihua.