The production of the CVD diamond layer can take place separately from the components’ surface. To achieve this, a CVD diamond coating is deposited on silicon or copper based substrates. Free-standing diamond foils with a layer thickness of 20 µm and above can be peeled off the substrate. Laser cutting allows the adequate tailoring of the diamond foils. Bonding and soldering processes are currently under research and are developed for „cold” application onto the component surface.
Doping and varying the grain sizes via manipulation of CVD process parameters allow the production of diamond foils with application specific properties. On the one hand, micro crystalline diamond foils with a very high heat conductivity (around 2000 W/mK) and a very low electrical conductivity can be produced, while on the other hand boron doped (p-conduction) diamond foils with corresponding micro and nano grain sizes can have electrical conductivities of up to 40.000 S/m and a thermal conductivity of significantly less than 100 W/mK. It was already possible to measure Seebeck coefficients above 350 µV/K. These completely different diamond foils are being further developed to improve thermoelectrical properties. The doping of Titanium and Vanadium for the n-conduction of diamond is another topic of research.
Application examples: