I'm seeking input from the various people that have in recent times made PCBs to plug into old microcomputers and minicomputers using PCB edge card connectors. There are quite a few companies (and coops) that offer very inexpensive PCB fab service, even in low volumes, particular for double-sided PCBs (vs. multilayer). However, I haven't found a PCB fab house that offers any reasonable deal on low volume runs of PCBs with plating of hard-gold over nickel edge connectors. Has anyone found a vendor that does? I was somewhat surprised at the difficulty in tracking down good information on best practices for PCB edge fingers. Several of the PCB companies suggested just using an ENIG (electroless nickel immersion gold) on the whole PCB, including the edge card connector, but that isn't really suitable. According to an excerpt of a draft of the IPC-4522 standard, ENIG gold is typically only 0.025 to 0.05 microns, and is not suitable for edge finger use for more than five insert/remove cycles. (It would be perfectly acceptable to have ENIG, HASL, or tin finish on the rest of the board.) A document from AMP recommends 0.4, 0.8, or 1.3 microns of hard gold over nickel, to withstand 200, 1000, and 2000 cycles before failure, respectively. The IPC-2221 standard suggests three categories: Class 1: 0.8 micron gold over 2.0 micron nickel, for general electronic products Class 2: 0.8 micron gold over 2.5 micron nickel, for dedicated service electronic products Class 3: 1.3 micron gold over 2.5 micron nickel, for high-reliability electronic products. The PCIe specs require 0.7 micron gold over 1.2 micron nickel. I'm perfectly willing to build prototypes for my own personal use using ENIG or even HASL with nothing special for the edge fingers, and be resigned to them not withstanding many cycles. However, if I were to offer a product for sale to other hobbyists, I don't think that would be acceptable. I suspect that the original PCI specs had a similar requirement to PCIe. I estimate that a 32-bit PCI edge card requires about 1300 mm^2 of gold over nickel (counting both sides of the PCB), which works out to a little less than 1 mm^3 overall, which at recent gold pricing would be about USD $0.80 in gold. An Apple II card would probably have a roughly similar amount of gold, while S-100, Qbus, Omnibus, Multibus, etc. cards would require several times that. I'd be delighted if in small volume I could pay less than an additional $25 each to get the hard gold over nickel edge connector, but so far I haven't found a PCB fab comes even close to that. Eric