All, Thanks very much for your responses, most informative, especially that from the Rockwell twins! Regards, Iain. -----Original Message----- From: [log in to unmask] [mailto:[log in to unmask]] Sent: 31 August 2006 13:10 To: [log in to unmask]; Braddock, Iain Subject: Re: [TN] Conformal coating rework? *** WARNING *** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. Well Iain, it depends. You knew it was coming. There are a variety of approaches. Which one is used depends on whether you are talking about a small area, such as over and around a chip cap, or if you are trying to remove it from an entire assembly. For very local removal, such as field repair of a component, you can usually burn through the coating with soldering rework tools, such as thermal tweezers or soldering irons, hot knives, etc. You will still have to chemical strip the rework site to remove the residual polyurethane, but removing coating from a flat unpopulated site is much easier than doing it from components. I would not recommend micro-abrasion. It works, but a good urethane coating is very similar in hardness and composition to solder masks. When you get an abrasive powder that works well enough to cut through the urethane in a reasonable period of time, unless you are really really really (and I mean really) careful, you etch off the solder mask with it. Same consideration for chemical stripping. When you get a stripper aggressive enough to dissolve the urethane, it can also attack the solder mask, component markings, legend inks. The process has to be controlled very tightly. I am not familiar with the urethane you mention. We don't do urethanes here at Rockwell, or only sparingly. Usually, when I want to know how to remove a conformal coating chemically, I start with the manufacturer of the coating. What do they recommend? Go from there. Humiseal has a couple of stripping agents available, some made for urethanes. Phil Kinner at Humiseal Europe in the UK should be able to get you pointed in the right direction. Dynalloy makes a material called UResolve 411, which I have found to be an effective stripper. If you are interested, the US Air Force has one of their rework and repair manuals that are available on the web and it has a section on removal of conformal coatings. Don't know if this is the most current version though. http://www.robins.af.mil/logistics/LGEDA/documents/TechOrds/00-25-234rev2.pdf#search=%22%22Bond%20Breaker%20II%22%22 Hope this is more helpful than the goofball offline comments Hillman provided you. Doug Pauls "Braddock, Iain" <Iain.Braddock@MB DA.CO.UK> To Sent by: TechNet [log in to unmask] <[log in to unmask]> cc Subject 08/31/2006 01:31 [TN] Conformal coating rework? AM Please respond to TechNet E-Mail Forum <[log in to unmask]> ; Please respond to "Braddock, Iain" <Iain.Braddock@MB DA.CO.UK> Hey Techies, I'm interested in what processes people use to remove Polyurethane conformal coating in particular Robnor resin 313C, local or full board, with respect to IPC class 3 manufacturing. Micro blast? chemical strip? Regards, Iain. ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ******************************************************************** --------------------------------------------------- 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 ----------------------------------------------------- ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ******************************************************************** --------------------------------------------------- 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 -----------------------------------------------------