One comment: others have well detailed the issues around top and bottom SMT pads. Unmentioned was the fact that a pad can live on any layer, including non-copper layers.
This can be useful; I've used it to get pads of a component out of the way when I was using single-pad "components" to imitate the pins of an FPGA so that I could quickly swap them in PCB; that the pads still existed made it easy to snap the pseudopads into place so that routing accurately terminated on pad center once the original pads were restored to the correct (final) layer. I also have made assembly drawings by taking a photoplot of all the pads on each side of the board, reimporting it, and moving all the imported pads from each side to a mech layer, together with silkscreen for that side. (I used a scratch PCB for the import, then copy and paste once everything was on the right layer). But one should be careful about such uses, as with any use that is outside the common envelope; there can be bugs. For example, don't put holes into surface pads *as part of the pad.* Protel does not properly handle this, as I recall. Normally, we would not put holes in surface pads at all, for reasons which have been given, and if we want to put a hole into such a pad, we would do it with a via, which is just fine as far as Protel is concerned. [EMAIL PROTECTED] Abdulrahman Lomax Easthampton, Massachusetts USA * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
