Victor, As a really old rellic of the stone age, actuall pre-cambrian era, I've forgotten most what I learned in the late 60's and early 70's. However, I can tell you in those days platings were much different and much more robust for just the reason you are seeking answers. In those days, most all interconnects were effected using card edge connections. We specified something like .0005" gold over .001" nickel or some such thickness (when gold was under 32 dollars and ounce. Another important factor was gold hardness expressed in knoops. We also specified up to 500 or some such number of insertions/extractions. Speaks volumes doesn't it. No one I know currently specifies anything like this absurdity. As for flash or soft, gold, you are right about the number of insertions/extractions being very minimal. However, I cannot express numbers here and don't know if anyone else can. Burndy, an old time card edge connector supplier, used to have what they called "knife edge" connectors. These were tin lead plated and designed to be used with tin lead plated board edge connections. This provided a "gas/air tight" seal and gave some number of insertion/extraction cycles over flash coatings. This technology was cooked up because, mostly, gold was selling for around 800 dollars an ounce. Now we're in an era in which much less reliance is placed on card edge connections. Other interconnections are much more popular, useful, and reliable. So, the answer is there used to be one for your situation but it is not useful anymore. Without writing another book, I would simply say first check out your board shop and determine their hard gold capabilities, if any. Then, contact your connector suppliers and see what they say. Concurrence here should yield some answers to your question while understanding gold thickness over nickel thickness, gold hardness expressed in knoops, and number of insertion/extraction cycles. Most of the old documentation is contained, probably in some connector supplier's archives and in long ago, like me, dinosaur, mil specs speaking of which you may still be able to access as MIL-P-55110, MIL-STD-275, as well as federal metallization specifications referenced therein as gold, tin, lead, tin/lead, etc. Another old time guy still in this business is Happy Holden. He often hangs out on the Circuit Tree forum. He was one of the guys at HP doing serious gold back in my earlier times. He's a real gold guy. His name appeared on the technet forum a short time ago as someone was searching for him. It's in the archives. Would like to be of more help, Earl --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------