Gold edge connectors.

If the gold-plated female edge connector is an extender, who cares? Throw it away and buy another. The mechanical damage will occur on the gold side, not the tin side. It might not make great contact over the long-haul, but that's not the purpose of an extender.

Easy enough, except when your're debugging an already built widget.

Those details are the board fab's problem. ;-)

That was my point. You're not likely to damage the backplane connector, since it controls the wiping action (pressure). They may not have enought pressure to completely wipe the tin fingers, but that shouldn't matter a lot in a test environment (you can manually clean the fingers if need be). What you *might* damage is the gold fingers on the extended card, because they're inserted into the harsher springs, designed for tin fingers, on the extender.

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I was probably unclear. The original machine, now 26 years old, was $100,000 in 1979 dollars. It has gold female connectors on the 3 backplanes and gold fingers on the 40 boards that plug in. The original extenders had the same gold female connectors as the backplane and gold fingers as well. Here is a picture of this model.

Although 26 years old, the hours meter (which still works correctly) had 505 hours on it when we got it. It has logged 50 hours run since we got it running again 6 weeks ago. We need to do some troubleshooting and alignments on the second machine SO I need extender boards. $800 for 2 pairs of extenders with gold at both ends will do nicely.

I'm very appreciative of the info from John Woodgate on contamination and from Pooh Bear for confirming shorting lines at the end of the board for the plating process. The boards I've done all had gold connectors soldered to the boards but never with the fingers directly on the board.

Thanks GG

I ran across an interesting MIL spec this past week that said, "MUST have MINIMUM of 3% Pb".

...Jim Thompson

It certainly does if the softer material is scratched by a contact

No, I'm simply making a different point.

The extender has to plug into the original gold-plated female connector ( the equipment end ).

You really don't want to transfer tin-lead onto that !

Graham

Wiping action doesn't control the transfer of other material.

You seem to have completely missed the point.

Graham

Wouldn't the lead in the solder have more effect than the tin? Lead sure as hell attacks platinum if it gets hot enough. Don't know about gold, but I guess it behaves similarly. Remember platinum wires and borax bead tests in school chemistry? The bastards always gave you a lead compound, since you'd had to pay for your own platinum wire. Must have been getting payoffs from the local lab supply house.

We used nichrome wire.

Graham

There may be another possible solution. Many years ago, one of the connector companies (Berg, I believe) made an edge finger module that you soldered onto your PCB via thru-holes. This eliminated the need to have the PCB plated. I have no idea whether these creatures still exist or not, but it might be a cheaper answer to your problem.

You might also consider buying a standard proto board and cutting off the edge connector, or just laying out your extender card to piggy-back onto the proto card.

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Ah yes. Those '2 part' edge connectors are very nice. I wonder if anyone still makes them ?

Graham

Ah yes. That *really* dangerous stuff ! ;-)

Graham

Anything my MIL spec'd certainly was dangerous.

Cheapskate :-)

-- "Electricity is of two kinds, positive and negative. The difference is, I presume, that one comes a little more expensive, but is more durable; the other is a cheaper thing, but the moths get into it." (Stephen Leacock)

Found my notes where I jotted down the information:

"100% Pure tin is prohibited, internal or external. Greater than 3% lead is required."

And MIL-PRF-38534 was referenced. I'm not familiar with that spec... but it may have something to do with RAD-HARD, considering who my (non-disclosable) client is.

...Jim Thompson

Could be. Spec'd -55°C to +145°C

...Jim Thompson

I read in sci.electronics.design that Jim Thompson wrote (in ) about 'Gold edge connectors.', on Sun, 4 Sep 2005:

Or cold conditions?