CVD diamond heat dissipation application

Factors to be considered when integrating CVD diamond in a thermal system. To successfully integrate thermal management components into devices, the complete thermal conduction path as well as electrical requirements and thermomechanical stress must be considered. Although CVD diamond is extremely rigid and has a small thermal expansion coefficient (about 1 ppm/K), it is an ideal choice for high-power transmission window applications, but it is compatible with Si (2.6 ppm/K), GaAs (5.7 ppm/K) and There are obvious differences in commonly used semiconductor materials such as GaN (3.2 – 5.6 ppm/K), which poses greater challenges to thermal design engineers. Unless it is considered at the beginning of the design, the stress generated by thermal cycling can adversely affect device life and reliability. Two methods to control these stresses are composite semiconductor pre-cracking [6] and diamond interlayer; in diamond interlayer, the upper layer is used to balance the stress. When integrating diamond into a device package, the ideal geometry depends on many factors such as power density and cooling channel location, but the model design is relatively simple.

Fig. 1. Metallized CVD diamond heat sink

CVD diamond can be widely integrated into the heat dissipation solution in the following three ways: (i) independent individual diamond units are joined by metallization and welding, see Figure 3 (for example, using Ti/Pt/Au sputtering metal deposition and AuSn eutectic Soldering); (ii) Prefabricated wafers support multiple devices, enabling device manufacturers to process wafers in large quantities (such as metallization and placement). After such additional steps are completed, these wafers can be used as substrates for individual sub-assemblies. (iii) Direct use of diamond coating.