hi, you might consider using a polyurethane coating that has been around for decades and is still used in aerospace applications. it is very versatile. cab-o-sil can be added to it to thicken it up which means you could probably get by with just one application. it is used on assemblies that have glass diodes with no problem that i'm aware of. the material is solithane 113 (http://www.uniroyalchemical.com/solit113.htm). phil -----Original Message----- From: Roger M. Stoops [mailto:[log in to unmask]] Sent: Friday, March 02, 2001 8:29 AM To: [log in to unmask] Subject: [TN] Maximum Thickness of Concoat Y'all, Question engineer asked me today, how thick can polyurethane coating be applied? We apply three coatings with the following procedure: 1) dip 2) dry for 2-3 hours to eliminate most solvent vapors 3) bake for 4 hours @ 60 deg C 4) repeat until 3 coats. Third coat is also baked. Question to my able colleagues: Anybody know of any long-term problems with this method? Any test results? We need to do this to cover all sharp edges for electrical isolation during operation in potentially high moisture environment. Specifically, a housing that can fill with condensation before draining away, and we can't seal enclosure. Considered paralene, but it costs more to coat the board than to build it... TIA Roger M. Stoops, C.I.D., PCB Designer Trimble Engineering and Construction Division 5475 Kellenburger Rd. Dayton, OH 45424-1099 USA Ph: +01 937.233.8921 or +01 937.233.4574 ext 288 Fax: +01 937.233.7511 --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or 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 1.8d 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 delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------