Metal Core PCB (MCPCB) or Insulated Metal Substrate (IMS PCB) is a technology developed to overcome the thermal limitations of the FR4 material. Metal Core is a better choice than FR4 if your boards need to perform in high temperature environment.

Insulated Metal Substrate provides electrical isolation between the copper and the metal core by using a special dielectric with the peculiarity of having high thermal conductivity.

The most common material used in the substrate is aluminum, for this reason, these type of boards are usually known as Aluminum PCBs.

PCBs that require a lot of power usually generate a lot of heat. If your PCBs need fast cooling it is better to use Metal Core PCB than FR4. The following list includes some of the most popular applications that work great with this technology:

Insulated Metal Substrate Technology offers a great list of benefits when an application requires great heat dissipation.
Most engineers and designers rely on Metal Core PCB to take advantage of the following benefits (compared to FR4 PCBs):

It consists of a single copper conductive layer on top, a
metal base plate (e.g. Aluminum) to provide rigidness to
the circuit board and a thermal conductive dielectric
working as the insulator.

It has two copper layers and the metal core is between thecopper layers. Plated Through Holes (PTH) are used tointerconnect the acopper layers so SMT and THT componentscan be placed on both sides.

It has more than two conductive layers separated by thermaldielectric. In the bottom of the structure is the metal base. SMTcomponents can only be placed on one side. Not THT components are allowed, but it provides the possibility to make blind and buried vias with internal signal layers and power/ground planes.