What Buyers Must Know About PCB Surface Finishes

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Rich Krajewski
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Re: Immersion Tin
Rich Krajewski   7/23/2014 2:33:42 AM

Some of the mitigation techniques are controversial, according to



NASA's had their share of trouble with tin. In this doc, they say, if you can't live with tin whiskers, don't use tin:



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Immersion Tin
docdivakar   7/22/2014 3:40:23 PM

Regarding Immersion Tin, one needs to be careful about PCB floor planning. Under certain conditions, Tin Whiskers can pose a big headache via shorting. Additives to Tin as well as stress relieving can lessen the potential for Whisker growth, see:


MP Divakar

Rich Krajewski
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Supply Network Guru
Re: Did you mean
Rich Krajewski   7/21/2014 2:30:46 PM

You know, I'll bet a cheap hairspray from the dollar store would do a good job protecting PCB surfaces from tarnish, especially if the product is going to be replaced with a new model in 12 months. That's probably what they do in some places.

Rich Krajewski
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Supply Network Guru
Did you mean
Rich Krajewski   7/21/2014 12:54:48 PM

"Silver is more expensive but does not react with the copper traces so its shelf life is longer."

You can see that silver and copper form a galvanic pair, too. However, in that pair, copper is more anodic, according to the references below. With tin-copper, the tin is more anodic. At least, that is the relationship in conditions of salt and humidity (or saltwater).

The difference in anodic indexes for silver and nickel-copper alloy is rated for harsh environments, at 0.15 V.







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