The "silicone contamination" question has been raised in my plant again. An end user has requested that we certify that we don't use ANY silicones in our electronic assembly facility (they have paint lines). In various locations we use silicone RTVs and the like to seal face plates, in addition to using RTVs in the maintenance areas for gasketing. Are these "silicones" a threat to our customer regarding carrying contamination into their plant? *In a word, yes. I know that in our facility, silicones are a major contributor to conformal coating adhesion problems, which rapidly become MY problem. Paint would likely be similar. Coatings do not like to adhere to silicone RTVs, or to any outgassing or exuded oils or cure byproducts, or "re-distributed" silicones. And, knowing that various silicone oils and mold releases are a definite no-no, are there other classes of silicones that are dangerous/safe? *The two most common here are silicone RTV adhesives and silicone thermal grease (silicone gel filled with zinc oxide particles). Our manufacturing procedures make sure these are very closely watched items, and life in manufacturing would be easier if we could get certain concepts through to certain design engineers (e.g. with a baseball bat). RTVs are mildly cleaned before coating to get the exuded alcohol cure byproducts and the silicone thermal grease does not go on until the automated wash processes are over. This prevents our saponifier chemicals from washing the stuff out. We also maintain a very aggressive preventative maintenance schedule to make sure that even if there is silicone contamination, it does not build to problem proportions. We are currently looking at non-silicone alternatives to both materials. *As far as mold release agents go, PTFE agents are more common, but represent the same threat of adhesion loss that silicone does. If you are using circuit boards, be advised that the use of silicones sometimes occurs in PWB manufacturing, so you may have silicone surface residues coming in from the boards shop and not know it. While not a common occurrance, it is something to think about. Where does one find references to such? *Well, you just asked the best source for technical advise (TechNet, not me). I don't know if you will find published articles on the topic. The best experience in manufacturing problems comes from bad experiences in manufacturing. Because of the "L" word (liability), most manufacturers do not publish articles admitting they EVER had a manufacturing problem. You might look for technical bulletins on Dow Corning's web site. Doug Pauls Rockwell Collins --------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------