High Efficiency Heat Sinks from Polycrystalline Diamond

While absolute power levels in microelectronic devices are relatively modest (a few tens to a few hundred watts), heat fluxes can be significant (through 50 W/cm2 in current electronic chips and up to 2000 W/cm2 in semiconductor lasers). Diamond heat sink enable heat transfer rates well above what is possible with standard thermal management devices. We have fabricated heat sinks using diamond, which has the highest temperature thermal conductivity of any known material. Polycrystalline diamonds manufactured by chemical vapor deposition (CVD) are machined by laser and combined with metallic or ceramic tiles. Cooling by fluid flow through micro-channels enhances heat removal. These unique attributes make diamond based heat sinks prime contenders for the next generation of high heat load sinks. Such devices could be utilized for efficient cooling in a variety of applications requiring high heat transfer capability, including semiconductor lasers, microprocessors, multi-chip modules in computers, laser-diode arrays, radar systems, and high-flux optics, among other applications. This paper will review test designs, heat flux measuring system, and measured heat removal values.

General properties of diamond

The most important properties of CVD diamond are the

@Unsurpassed hardness

@Extremely high thermal conductivity

(＞1800W/mK，five times that of copper)

@Broad band optical transparency

@Extremely chemically inert:

Not affected by any acid or other chemicals

@Graphitization only at very high temperatures

(T＞700℃ in an oxygen containing   and 1500℃ in an inert atmosphere)