CVD diamond possesses extremely high thermal conductivity, especially in the form of large-area, free-standing sheets, making it by far the most ideal heat sink material. Its most important application is heat dissipation for high-power-density electronic devices. Studies have shown that for every 10 °C increase in the operating temperature of a laser diode, its lifetime decreases by 50 %. Using CVD diamond as a heat sink material can increase output power, reduce diode junction temperature, thereby significantly extend device lifetime, and make the output optical wavelength more stable.
Another representative application of CVD diamond in heat sinking is the TAB (Tape Automated Bonding) tool used in large-scale integrated circuit assembly. TAB tools are used in the bonding process of integrated circuit chips with many pins, such as IC cards, calculators, and liquid crystal displays. Their characteristics are heat resistance, wear resistance, corrosion resistance, and especially excellent thermal conductivity.
With the continuous development of CVD technology, the transmittance and thermal conductivity of high-quality diamond films produced are now very close to those of the best natural diamond (type IIa). Moreover, large-area and curved surfaces can be achieved. Although diamond-like carbon films prepared on silicon have a broad infrared transmission band with infrared transmittance close to 90 %, their mechanical properties are inferior, and their adaptability under harsh environmental conditions is relatively poor.
CVD diamond films have excellent heat dissipation properties. As electronic devices become miniaturized while their power continues to increase, the resulting heat dissipation problem has become a key issue in microelectronic packaging technology. Currently, CVD diamond films are already used abroad in heat pipes, mainly to solve system-level heat dissipation problems caused by high-power, high-heat-flux components, including high-power laser diode arrays, two-dimensional multi-chip modules (MCMs), and solid-state microwave power devices.