Richard, I'm familiar with the acetyl cure RTVs... nasty on several fronts. We have an electronics grade RTV for high voltage potting and a low durometer epoxy that has worked well in sealing a "thru-hull" sensor. The conformal coating we usually use is acrylic based and I've had issues with attempting to clean dirty field returns without stripping off the coating. Thanks for the input. Phil -----Original Message----- From: Stadem, Richard D. [mailto:[log in to unmask]] Sent: Thursday, February 26, 2009 12:06 PM To: TechNet E-Mail Forum; Phil Nutting Subject: RE: [TN] Conformal coating or encapsulating Your choice may be dependent on the cost of the assembly. If you want it to be reworkable should it fail during periodic testing, then a reworkable CC may be the way to go. Potted assemblies are not very reworkable. So the cost of the assembly may be a consideration if you have to throw it away when it doesn't work. Secondly, if you do choose an RTV compound and encapsulate it, make sure you use an electronic-grade RTV. Many RTVs used for potting electronics are not meant to be used for that purpose, and corrosive reactions are common when this happens. Conformal coating is a barrier, but usually is not an impervious hermetic seal. Moisture can and will condense onto areas not perfectly sealed inside the coating, and moisture condensation inside of the sealed box can be absorbed inside of the CC. I have performed a combination of potting over high-reliability components and CC only over specific components that will probably require rework within a 3-10 year lifetime. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting Sent: Thursday, February 26, 2009 10:53 AM To: [log in to unmask] Subject: [TN] Conformal coating or encapsulating Hi all, I'm working on a design that will have some lithium batteries on a circuit board. The board will be in a marine application where it must be waterproof, sit idle for 5-7 years and must work during an emergency situation. No maintenance is expected or desired. Should I conformally coat the batteries/board and install in a gasketed (NEMA?) box or should I encapsulate the board in RTV or epoxy? Thanks in advance, Phil Nutting Design for Manufacturing Engineer Kaiser Systems, Inc. 126 Sohier Road Beverly, MA 01915 voice: 978-922-9300 x1310 fax: 978-922-8374 e-mail: [log in to unmask] www.kaisersystems.com Note: All the information contained in this e-mail and its attachments is proprietary to Kaiser Systems, Inc. and it may not be reproduced without the prior written permission of sender. If you have received this email in error, please immediately return it to sender and delete the copy you received. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 ----------------------------------------------------- Note: All the information contained in this e-mail and its attachments is proprietary to Kaiser Systems, Inc. and it may not be reproduced without the prior written permission of sender. If you have received this email in error, please immediately return it to sender and delete the copy you received. --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 -----------------------------------------------------