On Thu, Nov 29, 2018 at 11:52 AM Eric Smith <space...@gmail.com> wrote:
> 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. > I can't find any figures for ENIG, but hard gold is expected to last for 300 to 1000 mating cycles, depending on the plating thickness. Since ENIG has about 1/15 as much gold, one might expect it to last 20 to 60 mating cycles at most. Possibly fewer since there's not only a lot less gold (and less nickel), but also a different application process not engineered to support surface mating.