Dymalloy is a metal matrix composite of 20% copper and 80% silver alloy matrix with type I diamond. It has a very high thermal conductivity of 420 W/(m·K), and its thermal expansion can be adjusted to match other materials, such as the silicon and gallium arsenide used in computer chips. It is chiefly used in microelectronics as a substrate for high-power and high-density multi-chip modules, where it aids with removing waste heat.