Power electronic substrate-Insulated
Insulated metal substrate
Insulated metal substrate (IMS) consists of a metal baseplate (aluminium is commonly used because of its low cost and density) covered by a thin layer of dielectric (usually an epoxy-based layer) and a layer of copper (35 µm to more than 200 µm thick). The FR-4-based dielectric is usually thin (about 100 μm) because it has poor thermal conductivity compared to the ceramics used in DBC substrates.
Due to its structure, the IMS is a single-sided substrate, i.e. it can only accommodate components on the copper side. In most applications, the baseplate is attached to a heatsink to provide cooling, usually using thermal grease and screws. Some IMS substrates are available with a copper baseplate for better thermal performances.
Compared to a classical printed circuit board, the IMS provides a better heat dissipation. It is one of the simplest way to provide efficient cooling to surface mount components.