To Chris Stack: The short answer is that the process being discussed is what you describe as Soldermask over Tin/Nickle, and/or the "Santa Clara Process", although I have never heard it described as such. I suspect that it has been dubbed the "Santa Clara Process" because Bob Mack, of Santa Clara Circuits (now defunct) had a patent on such a process/finish. >From a fabricators point of view, the principle problem with the process was that the Tin Nickle finish tended to accelerate the Copper etching, because of the galvanic effect, and if it was not compensated for, it caused slivers of Tin/Nickle to shred from the sides of the traces, and cause shorting. Tin/Nickle is also notoriously difficult to "activate" once it has gone passive, and thus suspect that soldering to old boards was a challenge. Rudy Sedlak RD Chemical Co. *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************