Hello, TechNetters, I was wondering what others are calling out for flatness requirements on double sided boards with surface mount components. IPC-A-600 calls out 1.5% but with a caveat that automated assembly and surface mount may require more stringent requirements, and refers to IPC-D-275. The most stringent callout in D-275 for a 0.062" double sided board is 0.9%, and this is classed "reduced producibility". If we have, say, an 8.5"x11" board with 0.9% bow or twist, I know we'll have difficulty running it down our lines. What are others calling out, and how have your fabricators responded? Some of mine are balking at 0.7%, saying it can't be held (would have to be sorted, possibly increasing cost) because of variability in the base material. I think 0.7% is met most of the time, but every once in a while... Thanks for any input. ***************************** * Pat Bailey * * Supplier Quality Engineer * * Zytec Corporation * * 1425 E. Bridge Street * * Redwood Falls, MN 56283 * * * * phone 507 637-2966 x355 * * fax 507 644-3720 * * e-mail [log in to unmask] * ***************************** ############################################################## 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. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ##############################################################