Can someone please explain why the internal pad size is calculated (per IPC-D-275 and IPC-2221) based upon the maximum diameter of the plated hole instead of the drilled hole diameter? Many suppliers drill the holes a little larger than the maximum diameter of the finished hole. It seems like the pad size should be based upon the drilled hole since the annular ring is measured at the foil. The fabrication allowances don't seem to be quite enough to accommodate this. I'm sure this has been discussed before, I just need a refresher. Bill Dieffenbacher Lockheed Martin ############################################################## TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c ############################################################## To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TECHNET <your full name> To unsubscribe: SIGNOFF TECHNET ############################################################## Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information. If you need assistance - contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ##############################################################