Gary Willard wrote: > My main question is, are there any major concerns or advantages in > having the vias connecting directly into the plane without relief, I > vaguely recollect concern expressed over reliability of these > connections if extreme thermal cycling is undertaken. There are definite electrical advantages to direct plane contact, we've done this for years. The inductance of the supply/return loop drops enough to notice (important for high-speed switching along with proper placement of vias and decoupling), as does re- sistance (important for high loading). Plane performance on dense boards improves as the planes are noticably less "broken up". Also plane splits are a little easier to accomplish without leaving bad etch geometries behind. I agree that if you're doing your power/gnd routing well, there is a price to pay in rework. I don't think the thermal relief image makes any difference to via reliabilty over thermal cycling, since the usual thermal geometry looks like a normal pad at the junction to the PTH barrel. Our SOP is to call them "direct hits" with a small flash (so every one knows that we know). For some fabricators, who require therm- al relief, we point to the appropriate thermal geometry for sub- stitution. I wish I knew why they do that. I was told once it was due to "pink ring" but gather that's old news. Fabricators? Regards, Jeff Seeger Applied CAD Knowledge Inc Chief Technical Officer Tyngsboro, MA 01879 [log in to unmask] 508 649 9800