I was thrilled when the subject of thermal vias vs. direct-connect vias came
up, because we were just discussing whether we should "go direct" last week.
After reading all the responses... well, I'm just a little worried about it.
Rather than quote everybody, here is a summary of what my boss will read if
I show him this discussion:

Two people, K.Barret and [log in to unmask], have used direct connections
extensively, in all environments, all sizes, varied layer count, no
problems. (and one ships about a million boards per year to prove it)

B.Luthor concerned about heat transfer to plane, one reply stated trace from
SMT pad to via was a thermal in itself. (I would tend to agree on that one)

One side discussion about a PINK RING problem, without enough explanation to
learn how pink ring would affect a board or how it is related to direct vias.

Another side discussion about clearance vs. fab allowance, and another about
reduced clearance (anti-pad) sizes. Won't affect our decision.

A warning from Norm about CTE mismatch and the danger of board damage if
direct connections are used.

One reminder from G.Ferrari about the value of formal test procedures and a
warning that what works for one design may not be appropriate for others.

-=x=-

Thanks to all who participated, this thread came along at the PERFECT time.
Our board vendors don't care WHAT we do, so it is up to us. But before I go
show this to others and we make the decision, are there any other issues
that got left out?  any elaboration necessary?  any final comments?

NOW THAT I THINK ABOUT IT, ALL OF THE REAL-WORLD RESPONSES WERE FAIRLY
POSITIVE, AND ALL OF THE NEGATIVE RESPONSES WERE KIND OF THEORETICAL..!
Am I misinterpreting?  Are there any REAL horror stories out there?

Also, if we remove the thermal apertures from our pwr/gnd via padstacks,
should we replace them with a small aperture to "show" something there, or
just leave it empty? Seems like it would be hard to track down connections
looking at "direct-connected" film, any problems there?

thanks in advance, (and Sorry to those who were tired of this subject)

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