Metal Core PCB
The metal core of the thermal PCB can be aluminum (aluminum core PCB), copper (copper core PCB or a heavy copper PCB) or a mixture of special alloys. The most common is an aluminum core PCB. The thickness of metal cores in PCB base plates is typically 30 mil - 125 mil, but thicker and thinner plates are possible.
MCPCB, Metal Core PCB, thermal PCB - whichever name you prefer, they are all boards which use a base metal material as the heat spreader portion of the circuit board.
Base metals in the MCPCB are used as an alternative to FR4 or CEM3 boards for the ability to dissipate heat away from critical board components and to less crucial areas such as the metal heatsink backing or metallic core.