Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

I'm looking to stretch my luck by trying a design that uses all SMT packages. At the moment I am pondering how to tackle the thermal pads commonly found on SMT power converter packages (for an onboard buck converter).

The data sheets commonly specify that a pattern of plated vias should be used to conduct heat from the thermal pad of the package on the top copper layer to the bottom layer. The idea, obviously, is to provide more copper surface area for radiating away waste heat. My problem with this is that I don't have a way to plate through holes. I am using old-fashioned copper rivets to connect between layers. And while the rivets are smashed pretty flat by the tool, you can definitely feel where they are, and the tool also tends to leave a slight deformation in the surrounding copper layer. I am concerned that this could cause problems with reflow soldering.

I thought about simply making a larger copper area on the component side of the board, but the relevant data sheets are also adamant that circuit paths to supporting components must be as short as possible.

I've got a couple of ideas to try:

1) Use riveted vias in a copper area that's as close as possible to the package without actually being embedded in the thermal pad landing. But will they still conduct away enough heat?
2) Forget the through-holes and stick some kind of heat sink on top of the package. But again, since the package is quite small, and not designed for a heat sink on top, will it work?

Any other suggestions? Has anyone here tackled this sort of thing before?