Daan, It is almost never the same in X and Y. They will always be slightly different due to the grain and non-grain (warp and weft) of the material. We specify grain in a fixed dimension and have developed consistancy based on that. -----Original Message----- From: d. terstegge [mailto:[log in to unmask]] Sent: Tuesday, June 13, 2000 2:53 AM To: [log in to unmask] Subject: [TN] stretch and shrinkage of bare boards I have a question for the fab-guys out there : Is it likely for a bare board that shrinkage or expansion is different in X- and Y-directions ? Or maybe even a stretch in X and a shrinkage in Y ? Or is it more common that both values are the same ? The question behind this question is whether a pick&place machine that uses only 2 fiducials can compensate for both dimensional inaccuracy and rotation of the board in the conveyor. I think this is possible, but only if dimensional changes in X and Y are equal. Kind regards Daan Terstegge Unclassified mail Personal website: http://surf.to/smtinfo ############################################################## 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 ############################################################## ############################################################## 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 ##############################################################