I've been doing some reading on designing a board around TI PowerPAD ICs (specifically, the TLC5940 16-channel LED driver), which have thermal pads on the underside for direct soldering to PCBs. During my exploration, I came across this post on another forum about creating thermal vias in Eagle:
One of the commenters says:
There are three ways to do this.
1. Create the vias in your layout every time, remember how you did it, etc.
2. Add them to your part as pads, not vias, and have a big block of them in your symbol that you have to connect to GND in your schematic later.
3. Switch to Eagle 6 and do option 2 again, except now you can connect all those pads to one GND pin in the part, not the schematic. Or do option 1 again, and save your layout to a minimal project, and you can copy and paste it with signals intact.
Here is something very simple I have done, which is to simply place the chip directly on top of a ground plane to see what would happen:
What I would like to know is, how does one even connect the thermal land on the board to the ground plane in eagle? If you look at the image, you can see that the ground plane avoids the thermal pad entirely, and I don't know how to assign a signal of GND to that pad, which I assume would fix things.