James, thanks for the response. We bought some ESD brushes and found a big and professional ionized air blower. We placed the coated board on a grounded workbench and switched on the blower to stream ionized air across the board. And measured with a ESD instrument. Then we swept the ESD brush a couple of times across the board. Guess what happened. The instrument read 3,000 Volts! I'm not going to try an explanation how this could happen. Got no time just now. Next experiment. We took the 'charged' boards and dipped them in DI water for a couple of seconds, lifted them up and dried them rapidly with a dry nitrogen pistol. New ESD readout gave 0 Volts. We skip all thoughts about ionizers and brushes and go for rinsing in DI water. Thanks, you all that contributed with ideas. Inge ----- Original Message ----- From: "James Verrette" <[log in to unmask]> To: <[log in to unmask]> Sent: Wednesday, March 28, 2007 2:52 PM Subject: Re: [TN] ESD charges in conformal coatings Inge, Have you tried an Anti-Static Film Cleaner like "Film Kleen" from Anchor? There is a Film Kleen, Film Kleen II, Diazo Film Kleen, not sure what the difference is. Circuit Check recommends the Diazo Film Kleen for cleaning their fixtures. I also stumbled across an Ionizer that fits on can of compressed air. http://www.kinetronics.com/cgi-local/SoftCart.100.exe/online-store/scsto re/cai.html?L+scstore+zczg8040ff939793+1180305318 Jim Verrette Electrical Engineer -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Hernefjord Ingemar Sent: Tuesday, March 27, 2007 7:09 AM To: [log in to unmask] Subject: [TN] ESD charges in conformal coatings Hi all gnus and gurus, =20 Sometimes, we need clean boards from dust and dirt. Field practise, no proffesional facilities. Not surprisingly, you move electrons from the conformal coating's surface. I have measured several kilovolts at a distance of one inch from the board. The highly insulating acrylic coating keeps the charges effectively for hours, quite expected too. ESD brushes not much better. Not even grounded ESD brushes works. I get rid of the surface charges if I dip the board in water, quite natural, because of the large contact area and polarisation media. EE in the US, did an investigation during 8 years. They ranged the 23 most common electrical failures and their sources. Conformal coating charges came as number 9. Question: anyone who can recommend a dust and dirt removal method, when dry brushes don't work and water is not allowed? Inge --------------------------------------------------- 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=3D4.3.16 = 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 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------