Wayne, I agree with Richard's response in separate email and to an extent with you, Wayne. Teardropping is regarded as "best practice" by many and normally comes as an automatic, semi -automatic or manual process on layout tools. I'd rather do it in-house as the design rule checks can still be made and track entry adjusted to maximise coverage. Where compromises occur, they can be managed. Remember also, on very high speed designs, the signal integrity characteristics will be altered by addition of the teardrop and this needs to be verified by appropriate simulations - at very high speeds, vias can look like band-pass filters due to inductive/capacitive effects above certain frequencies/bit rates. Additions at PCB fab house cannot account for this and may upset operation electrically. Barbara, The enhancement of track entry with teardrops at feature sizes you describe will help, but nothing protects against any fab house's bad process if they're drilling is not up to par (i.e. the pad annulus to adjacent copper features on non-teardropped layers - the barrel could be closer than you want). And there's nothing wrong with being an "old-fashioned girl" - would that there were more ;-) Kind Regards, Phil. -----Original Message----- From: Wayne Thayer [mailto:[log in to unmask]] Sent: 06 July 2006 14:32 To: [log in to unmask] Subject: Re: [TN] Validy of Teardropped vias? *** WARNING *** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. Barbara- That's usually a job done in CAM--the PCB fab usually will contact you if they feel like doing it. Teardropping drastically reduces the probability that minor breakout due to layer stackup lamination issues, over etching, or drill mis-targeting will cause a continuity failure. But if your annular ring is 5mils or greater, the probability is probably pretty darned small anyway. Wayne Thayer >>> [log in to unmask] 7/6/2006 9:17 am >>> Hey Y'all, It is my habit to teardrop a trace coming into a through-hole pad if the trace is 5 mils or less and the annular ring of the pad is 5 mils or less. Does this improve manufacturability of the bare board, protect against drill-out, and fracturing of the point where the trace enters the pad under shock and vibration? Or am I an old-fashioned girl? Barbara Burcham, C.I.D. Sr. PCB Designer RFTrax a Fairfield Co. 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