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    "Tin Whiskers" and electrical part failure ..

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    Bob Latino
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    "Tin Whiskers" and electrical part failure ..

    Post by Bob Latino on Mon Dec 16, 2013 3:50 am

    For the past 6 decades Western Electric, Bell Labs and more recently NASA have studied part failures that were brought on by "tin whiskers". These tin whiskers are hair-Like crystal structures that sometimes grow from surfaces coated by mostly pure tin or zinc or cadmium finishes. These are rarely found in audio gear but are more often found in relays, connector pins, IC leads in satellite and miltary electrical gear. Although these whiskers have been studied for years there is still no firm theory as to why they grow and how fast they grow? NASA has had a number of their satellites go down because of this problem. Ok - This is not really Dynaco audio related but it is maybe something you "solder slingers" might find interesting? A 2006 NASA service bulletin about the tin whiskers is at the link below ..

    NASA tin whiskers study - 2006

    Bob

    peterh

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    Re: "Tin Whiskers" and electrical part failure ..

    Post by peterh on Mon Dec 16, 2013 1:04 pm

    And the most efficient workaround is to use lead/tin solder ( the normal 60/40 as we all know it.

    sKiZo

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    Location : Michigan USA

    Re: "Tin Whiskers" and electrical part failure ..

    Post by sKiZo on Mon Dec 16, 2013 2:14 pm

    More of an issue with solid state due to the close proximity of connections. It's a problem with silver coatings too. TI did a lot of their early IC packages that were subject to corrosion and whisker issues. Here's a closeup pic from my Carver C4000 ...



    Unfortunately, this one has already been dremeled clean, but you can see the black crud that's still on the pins. Different corrosive process, but same nasty results. Stuff gets fuzzy over time and can short the pins. Once the connections are cleaned, you need to seal them to keep it from happening again - either a non-conductive clearcoat or dialectic grease works well.

    PS ... it's mostly the newer "eco" blends that have issues. You shouldn't see it with standard 60/40 like Kester 40. I use Cardas Quad myself - that's eutectic, but won't whisker if you do it right.

    I love my Cardas Quad ...


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