• Thread starter Biggs, Daniel (IndSys, GEFanuc, NA)
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Thread Starter

Biggs, Daniel (IndSys, GEFanuc, NA)

Greetings, I was wondering if anyone out there is familiar with this standard and/or know of a coating that can be used on PCBs to protect them from potentially corrosive gases and airborne contaminents. The standard specifically deals with process measurement and control systems. Thanks, DB GE Industrial Systems Daniel Biggs Test Engineer Hardware Design Services GE Fanuc Automation PO Box 8106 Charlottesville, VA 22906 PH: (804) 978-6946 Fax: (804) 978-5588

Schanker, Jacob

Daniel: I am not familiar with the standard mentioned. In the past, I have used silicone-based conformal coatings on printed circuit boards to isolate them from the environment. I believe GE is one of the manufacturers of these materials. Regards, Jacob Z. Schanker, P.E. Director of Agency Compliance Adaptive Broadband Corporation 615 Fishers Run Victor, NY 14564 +716 742 6154 (voice) +716 742 6102 (fax) +716 820 7364 (US cellphone) +0777 992 5368 (UK cellphone) [email protected]

Alastair Fordyce

I can't comment expressly about the ISA standard but conformal coatings on PCB's are very common. Talk to any serious industrial electronics manufacturer and they will advise you. There are various types available right up to potting compounds. You will probably have to choose one that is UL/CSA approved. The compound is applied to the PCB by brush or spray. If there are any connectors or potentiometers on the PCB, these will have to be masked (can use a removable paint-on silicon rubber) before spraying. Best regards, Alastair Fordyce REA, NZCE,CQA Systems Engineer Bremca Industries Limited PO Box 7169 Christchurch NEW ZEALAND tel +64 (3) 332 6370 fax +64 (3) 332 6377 e-mail [email protected]

Nilanjan Mudhopadhyay

Ananth Could you enlighten abit more on G3 Nilanjan > For Corrosive constituents like SO2 gases the coating standard to be followed is G3.
If G3 environment requires conformal coating then what is required for G1 and G2 environment? Are the PCB tracks have more width or height to be suitable for G1 and G2 class? Why this is not possible for G3 class?

Kevin Jameson

In regard to this standard, special systems are typically installed to prevent circuit corrosion from corrosive gases. Its very common at refineries, paper mills, smelters, etc. These systems keep the room pressurized with purified air. Temperature and humidity control are critical as well. There is typically not a need to coat boards when ISA-S71.04 is followed.

If you have further questions, please feel free to contact me at [email protected]