Doug, I believe my extreme phobia came about in the days of us processing 'elephant snot' for potting automotive. One had to be extremely careful not to contaminate things with that silicone - cured or not. I have basically adhered to that rule of thumb in the years since, and have not experienced problems. Possibly a case of being overly cautious, but it sure beats the other extreme! I would not process any uncured materials in the plasma chamber - silicone or other. I still avoid the cured silicones if at all possible. I remember one MEMs device that needed to be attached with a thick section of low durometer silicone gel, then wire bonded - we did not plasma clean it.! "power" is somewhat unique to each unit, but when I go to ash the chamber, I will drive the power to 300-500W [whereas the Argon plasma may only be 150-250W], under higher than normal pressure for 20-30 minutes. The 'dense' energetic plasma seems to do a good job of cutting through the organics. Make it a standard cycle and do it every Monday morning, for example On some units you can automatically have it cycle through an oxygen plasma then finish up with an argon plasma Being below the explosive limit at 4-5%, I don't think you will have opportunity to eliminate any overlords, but do watch the addition of baked beans to the recipie! Look at the Diener cleaner . http://us-plasma.com/ Their PlasmaBeam atmospheric plasma units are kind of slick. Is it 100% ESD safe is always the question.. Steve From: [log in to unmask] [mailto:[log in to unmask]] Sent: Friday, July 30, 2010 10:52 AM To: TechNet E-Mail Forum; Steven Creswick Subject: Re: [TN] Plasma Chamber Maintenance Thank you Steve. Does your silicone rule refer to cured or uncured silicone or both? And when you talk about "high energy", what wattage level are we talking about? How long an oxygen cycle do you recommend for burn off. I will have to play a little with hydrogen. Not sure if I know what you mean by arc plasma. In in-line ones that I have seen are largely made for things like bare boards, and not assemblies. Doug Pauls Steven Creswick <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 07/30/2010 09:22 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to Steven Creswick <[log in to unmask]> To [log in to unmask] cc Subject Re: [TN] Plasma Chamber Maintenance Doug, One of our rules was - thou shalt not put silicones in the chamber! Other than that, periodically we would use a really fine scotchbrite and clean room vac to physically clean the interior of the chamber. Then, as Joyce indicates, a nice high energy oxygen plasma to ash off any remaining organics and argon to knock off a few more offensive molecules. From a wire bonding point of view, I have found argon with 4% hydrogen to provide a slight edge on cleaning over straight argon. Not sure if that would apply to CC adhesion of not. Have you tried the arc plasma cleaners/surface activators. Can be made into an in-line process much easier than the batch type plasmas. Steve Creswick http://www.linkedin.com/in/stevencreswick -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Douglas Pauls Sent: Friday, July 30, 2010 9:01 AM To: [log in to unmask] Subject: [TN] Plasma Chamber Maintenance Good morning all, On a topic other than rhubarb, raiding my cubicle for prizes, and selling off my children, I have an actual technical question. We have started to use plasma chambers as a preparation for conformal coating and are having some excellent results. One of our IEs, with a background in the semiconductor industry, had indicated that the chambers can be items that are hard to maintain or high in maintenance costs. So, for you plasma chamber users out there, what have your experiences been with plasma chamber maintenance? Doug Pauls ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. 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