How to use thermal shells?

I have to model heat conduction and dissipation from a electronic component through a think layer of copper present over a PCB i.e. there is an electronic component fixed to a PCB. Between the electronic component and the PCB there is a thin layer of copper. The copper layer extends beyond the electronic component and can conduct heat form the electronic component and can dissipate it to air. Can I use thermal shells to model the copper layer. If I can then how do I use it? Should I create a separate surface (with out any parent volumes) between the boundary surfaces of PCB and boundary surfaces of the electronic component?