Actually a top side pad with a plated hole that has no pad on the back side is a valid condition... if the software will let you define it as such. So DRC should check the clearance of the plated hole to planes in the board and traces on inner layers or the back of the board if you have a reason to define this sort of structure. Otherwise, the software should restrict the use of such structures.
I have heard of one and a half sided boards, meaning single sided and plated through... This was done by some companies in the past to avoid damage to the back side pads during auto insertion of axial and radial leaded parts... the leads would sometimes catch on the inner side of the pads near the hole when the lead was forced into the hole by machines from the top side and would rip the pad off the back of the board. The plating protected the back side pad and the customer didn't want pads on the top because they would short to components or violate voltage spacing... DRC should be able to detect any traces that short to a plated thru hole... or violate voltage spacing from a plated through hole...and not just a pad. My 2 cents... Bill Brooks -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Monday, October 24, 2005 11:03 AM To: [email protected] Subject: RE: [PEDA] Strange feature.. DRC misses an error condition. My memory as well...by design, single-layer pads were considered to be SMT components, as therefore use of a hole with such a pad was considered non-sequitur (illogical). Frankly, I don't think it's a bug, at least for the time in which single-layer pads were introduced to Protel, back when microvias were little more than a twinkle in the IC designers eyes. Instead, the logical thing to do is place a multi-layer pad, define the desired hole size, and define all unused pad layers to a diameter of zero (0) for pad width. Since hole plating is executed only after the drill operation has been completed, any hole defined as a plated hole will be left unmasked and so will become plated. If plating of the hole is undesired, a note in your instructions should be sufficient to avoid plating. aj ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[email protected] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[email protected] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[email protected]
