Core Advantages of Synthetic Diamond Heat Spreaders The core advantage of synthetic diamond as a heat spreading material lies in its extremely high thermal conductivity, making it an ideal functional material to solve the heat dissipation problems of high-power devices such as computer central processing units (CPUs) and light-emitting diodes (LEDs).
Thermal conductivity surpassing traditional materials: It is often stated that the thermal conductivity of diamond is five times that of copper. Depending on the specific type, the thermal conductivity of Type I diamond is about twice that of copper, while Type II diamond is four to six times that of copper.
Extreme thermal conductivity data: At a temperature of 273K, the thermal conductivity of Type IIa diamond can reach 2000–2200 W/(m·K), and that of isotopically pure diamond is as high as 3500 W/(m·K).
Current Application Feasibility and Challenges Despite having tremendous theoretical advantages, the practical application of synthetic diamond as a heat spreading material currently faces some challenges, mainly reflected in two existing technological routes:
1、CVD (Chemical Vapor Deposition) diamond films: This material has been partially trialed, but the cost is excessively high (about $10 per square centimeter, plus expensive processing fees). More importantly, its own thermal conductivity is not very ideal; measured results are similar to those of Type I diamond produced by the static pressure method, which limits its widespread application.
2、Static pressure polycrystalline diamond sintered bodies: This route attempts to use low-cost static pressure single-crystal diamond (only a few cents per carat) as the raw material. However, the current process mainly produces Type Ib diamond, which has many internal structural defects and metallic inclusions, resulting in poor primary thermal conductivity. Furthermore, impurities and defects during the sintering process will further degrade thermal conductivity, and the final product's thermal performance may only be comparable to copper. It also faces the problem of high sintering and post-processing costs.
Ideal Solutions and Future Feasibility As long as the correct technological route is adopted, it is entirely feasible to manufacture cost-effective heat spreading materials using synthetic diamonds. To achieve this goal, breakthroughs are needed in the following areas:
Leveraging the advantages of artificial manufacturing: With synthetic diamonds, it is possible to artificially control the chemical environment of crystal growth (such as controlling the composition entering the crystal) as well as the temperature and pressure conditions to ensure the growth rate and quality of the diamond crystals.
Overcoming high-quality Type IIa single-crystal raw materials: Type IIa diamond possesses excellent thermal conductivity, which is essentially due to its relatively complete crystal structure and low nitrogen content. Under current technological conditions, it is entirely possible to grow this kind of high-quality single-crystal diamond.
Optimizing advanced sintering processes: Once the issue of high-quality single-crystal raw materials is solved, advanced sintering processes should be adopted to minimize defects that hinder heat propagation, such as grain boundary impurities, pores, and additives inside the polycrystalline sintered body.