On Wed, Nov 28, 2018 at 7:05 PM Chuck Guzis via cctalk < cctalk@classiccmp.org> wrote:
> > 2) is there some way to specify "hardened" or whatever plating for the > connector traces? > My last order from OSHPark came with all traces gold-plated. > Apparently, it's getting to be standard practice. > Sure, but that's just 0.05 to 0.125 microns of ENIG (electroless nickel immersion gold). That's not intended for mating surfaces, and will wear away after only a small number of connector cycles. For reliable edge fingers you need "hard gold" (AKA "hard electrolytic gold"), which is 0.75 to 2 microns of gold electroplated over 3 to 6 microns of nickel. (Be careful out there, a lot of places still specify the nickel and gold thickness in microinches.)