I'm looking at the various options for tenting/plugging/capping vias in
IPC-4761 (Via Protection Guidelines). None of the options seem to address
the thermal vias in power pads.
We are trying to
1) have a solderable pad, apply paste on that side (of course)
2) prevent solder from creating bumps on the heatsink side (of course)
3) avoid the cost of plugging/capping

IPC-4671 states that all forms of one-sided via protection are NOT
RECOMMENDED.

So here's the question - I know I have seen a picture of a thermal pad in
an IPC document where I could see vias with green mask material in them on
the paste side (the component side), but the green stuff was only in the
holes, which left the thermal pad exposed for soldering.
I don't think this would be called TENTING because there's no mask on the
pad. but is this an acceptable practice? Can I instruct a bare board
fabricator to put mask in holes from the top side, but keep the pad clear?
(I can't remember where I saw the picture!)

If that's NOT an accepted practice, is there a way to design the hole big
enough to plate but small enough to prevent solder flowing through the
other side of the board? I couldn't find a discussion of that in the
TechNet Archives

thanks,
Jack