John I helped develop some the cleaning systems for delicate boards including RF assemblies. I have done a great deal of conformal coatings. Conformal coatings are not to be taken lightly. There are major tradeoffs. First the cleaning.
Alcohol, on a Q-Tip, may be used for spot cleaning. Dunk cleaning will leave a flux residue in many shaft encoders, switches, connectors, and sockets. Alcohol will also dissolve some of the lubricants used on some types of switches. I wouldn't dunk clean even if I had a forbidden Freon degreaser. Conformal coatings are useful on assemblies like VCOs where mechanical stability is needed. They are also useful for high voltage circuits or circuits that are sensitive to leakage. It is a given that connectors and other contact surfaces must be masked before sealing. Conformal coatings will detune tank circuits where the air dielectric is replaced by conformal coating. They also make component replacement and reworking of boards hazardous and extremely difficult. Melting the coating with a soldering iron will cause a decomposition that emits hazardous gases and leaves an acidic residue that is almost impossible to remove. Therefore rework must be done by cutting through and removing of the coating before de-soldering. In short I do not see a significant benefit to conformal coating of Elecraft boards with the possible exception of VFOs, direct synthesis, and other boards that might be sensitive to microphonics. 73 de Fred, AE6QL -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of John Huggins, kx4o Sent: Wednesday, June 01, 2011 12:05 PM To: Elecraft@mailman.qth.net Subject: [Elecraft] K2 - Board Cleaning and Conformal Coating All, Being in the electronics biz, we usually wash boards post assembly with the usual products and in accordance with IPC610, etc. Often, the boards are sprayed with conformal coating: Some to handle "condensing environments" and others just because someone wanted it. My operating locations will include salty beaches and moist mountains. I couldn't find details in the K2 manual concerning these steps. I did find a few posts in old Elecraft archives, but need to ask... Are there any components used in the K2 boards that will not tolerate typical board washing procedures? (Most modern components expect this step, but some don't - often switches) Is there any reason not to conformal coat the boards once complete? (Cost is no object to make this last a long time in beach environments) Thanks. John ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
