I manage a captive PWB shop that produces 4,000 square feet per week of double sided plated thru hole product from .062 FR-4 copper laminate. Our product is a bit uncommon in that it has about .0004 inch hard nickel plated over the copper traces. Thru testing, we find a VERY thin layer (maybe 150 angstroms) of some contaminate that affects the surface conductivity when it is used as a switch half with a stainless steel snap dome. Using a Scotchbrite pad to burnish the surface provides a solution, but I would like to know the source of the substance and how to prevent it in the original process. Any ideas on the subject? Have it analyized. Try Auget (OJ) testing. You'll probably find that one of your post Ni Plate processes is depositing the film and producing the contaminate. Nickel is also prone to passivation when it's alone and left exposed for some time or exposed to thermal excursions. (eg, high temp bakes) Hadco Printed Circuits Tech Center Two / Watsonville _/_/_/_/_/_/_/ _/_/_/_/ _/_/_/_/_/_/ _/_/_/_/_/_/ _/_/ _/ _/_/ _/_/ _/_/ _/ _/_/ _/_/ _/_/ _/_/_/_/ _/_/_/_/_/_/ _/_/_/_/_/_/ Dave Hoover (408) 728-6677 Senior Process Engineer (408) 728-1728 Fax [log in to unmask]