As is known to all, dielectric layer is the most important part of MCPCB,which like prepreg on FR4 PCB.
Thermal conductivity is decided by dielectric layer, so the thermal conductivity more higher,the thickness of dielectric layer more thicker.
For 1w/m.k, the dielectric layer thickness is around 75-100um.
For 2w/m.k, the dielectric layer thickness is around 100-125um.
For 3w/m.k, the dielectric layer thickness is around 100-200um.
So, when we use the same raw material to produce metal core PCB, thickness of 3W/m.K finished metal core PCB is a little thicker than 2w/m.k and 1w/m.k.
