"Darrell Locke" wrote: > > Dear Colleages, > > We have seen an issue lately with spray-on conductive coatings used on the > inside of electronic enclosures. The coating works great for EMC, but there > seems to be a problem with adhesion and tiny flakes of conductive material > getting in the electronics. I'm thinking that the spray-on type materials > should not be used at all. Has anyone else experienced this problem?
Try to avoid it if you can. You're absolutely right about the problem of flaking onto or getting into any energized electrical parts. Safety will be all over you about using it. And because of that, you'll have to get: 1. a UL approval for plastic of the cover, 2. a UL approval for the plastic molder who's making the cover for you, 3. a UL approval for the conductive coating, 4. a UL approval for the marriage of the coating with the plastic, 5. and a UL approval for the vendor applying the coating to the cover. All approvals have to be verified of course in black-and-white for approval and for all subsequent factory inspections with of course appropriate Certificates of Compliance handy as well. As far as emi, it's sort of a once used thing. Don't use it on a cover that will be repeatedly removed and replaced. It's not meant to be disturbed to any extent once in place. And do not use it as a primary ground either. And it's all dependent upon the thickness of the layers for effectiveness. Oil based coatings seem to have a higher ohms-per-square than the water based coatings. You want to keep it down around less than 0.5 ohms. Been there, done that, sorta don't want to do it again. Other personal experience mileages may vary of course. All strictly my own 2 cents worth of opinion. - Doug McKean ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: pstc_ad...@garretson.org Dave Heald davehe...@mediaone.net For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
