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) *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************