Hello, We have been experiencing warping on certain PWB's from a specific supplier. I am curious on what the causes could be. In each instance, the PWB design layout was checked and found to be well balanced. Also our SMT Reflow Profiles were looked at for each PWB and found to be typical. The boards sometimes exhibit a slight warp right out of the MFG packaging and will warp out of spec on the first run. 1. We looked at dwell times, ramp up rate, actual temp, speed of PWB going thru the oven and all appears to be typical per each individual case. Is there anything else we could be checking for? 2. Is moisture absorption a concern - could it cause warping ? 3. Currently we do not bake PWB's prior to SMT Reflow - Is this something we should consider. Thanks in advance. Brian V. ################################################################ TechNet E-Mail Forum 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's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################