environment is similar to those frequently found in the oil, gas and petrochemical industry. For this, Type SR (Silicone) requires a thickness of

12.50 to 15.87 mils

as specified in table 1.

TABLE 1

MIL-I-46058C

THICKNESS REQUIREMENTS Type of CoatingThickness AR [18.98-22.95 mil] UR [15.98-18.95 mil] ER [14.98-20.95 mil] SR [12.50-15.87 mil] XY [12.49-15.87 mil]

As can be seen from the table, the traditional MIL standard, MIL-I-46058, provided more stringent standards for the various coating types, which GarrettCom believes are appropriate, considering the invasive effects of HS and other gases and chemicals commonly found in the oil and gas industry. GarrettCom is a participating member of the IEEE Standards Committee and hopes it will recommend these conclusions. Nonetheless, GarrettCom will continue to provide the coating thickness it deems best for its customers in the oil and gas industry.

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Conclusion

Silicone coatings provide excellent resistance to industrial chemicals, environmental heat and mechanical shock conditions, low stress on mounted components, ease of use and ease of removal, making it the choice for hardened industrial networking products such as Industrial ethernet switches and other electronic products.Using a thicker 14-mil silicone coating on PCB assemblies and all of the subassemblies inside of networking products, especially highly configurable products, is more time-consuming and costly than the thin coatings commonly being used. But GarrettCom believes the better protection and reliability of networking products in harsh environments demand no less than the right coatings for the right reasons. By Eileen R. Hess, PE, Member IEEE November, 2006 GarrettCom, Inc. Overland Park, KS, USA E-Mail: ehess@garrettcom.com 5