# Why the thickness of 3W/m.K finished metal core PCB is thicker than 2w/m.k and 1w/m.k?

_Published: 2016-04-02_

As is known to all, dielectric layer is the most important part of MCPCB,which like prepreg on [FR4 PCB](https://www.bestpcbs.com/blog/2016/04/prepreg-in-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.