Has anyone experienced poor conformal coat wetting due to moisture on the pwb surface? **Yes, er um, well, I have *heard* it happens other places, not here in the town of Perfect of course...... **Non Smart Ass Answer (NSAA): it depends largely on what kind of conformal coating you are using. Water-based, not a problem. Solvent based, could be a problem. You might also want to check on the amount of moisture that is in the coating itself. Ahem, I have *heard* that if you are feeding from a 55 gallon drum in the summer states in large mid-west corn growing states, you can have ambient moisture condensing in the barrel, combining with the coating. The coating properties and processing characteristics can be compromised, and may require longer bakes to cure the coating. May also lead to dewetting and have nothing to do with the assembly. Could moisture embedded in the pwb be problematic? **Could be, but I doubt it. Two hours at 250F should be enough to bake everything bone dry. In our process, we batch clean our boards which includes multiple deionized water rinse cycles. The product is then baked at 250°F for 2 hours. We have a new solder mask material which coats well prior to our processing. The 2 hour bake at 250°F has always proved adequate. Is anyone using a longer bake time? **I think you are overbaking. We dry ours at 100C for 60 minutes and it works fine. Your parts establish equilibrium with ambient humidity in the first 15 minutes anyway. What is the substantiation for establishing an extended time? **Whatever works and works consistently. There are no IPC specs that I am aware of on the topic. Doug Pauls --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------