It could also be a case that something in the potting compound is inhibiting the cure reaction, allowing bubbles to form later in urethane that is not fully cured. If the potting compound is not completely cured, there could be some chemical critters running around causing havoc. Are you thinning the urethane to spray? Got any pictures that Steve could put on his web page to look at? Doug Pauls Phil Nutting <PNutting@KAISERS YSTEMS.COM> To Sent by: TechNet [log in to unmask] <[log in to unmask]> cc Subject 01/24/2006 09:29 Re: [TN] Conforma Coat (Urethane) & AM bubbles Please respond to TechNet E-Mail Forum <[log in to unmask]> ; Please respond to Phil Nutting <PNutting@KAISERS YSTEMS.COM> Kelly, Sounds like either a chemical reaction or an air void that is working its way to the surface during heat curing. Phil Nutting -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Kelly Morris Sent: Tuesday, January 24, 2006 10:25 AM To: [log in to unmask] Subject: [TN] Conforma Coat (Urethane) & bubbles We've got a problem here, where we're hand spraying a urethane conformal coat on over a rectangular inductor. The inductor body is a plastic tube, with potting to fill. The top is not always flat (sometimes concave). The problem is that bubbles appear in the conformal coat on the potted surface, sometimes right after bake and sometimes days after. Any ideas on what the root cause is and how to prevent the bubbles? --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------