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Matte tin finish

jim_bob

#29841

Matte tin finish | 4 August, 2004

Regarding Lead Free component finishes, vendors are zeroing in on matte tin plating as the finish of choice. What test are performed, to determine if a finish is "matte" type (vs. non-matte)?

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#29846

Matte tin finish | 4 August, 2004

It's not clear. Virtually all component suppliers have done accelerated testing on matte tin finishes. Many are posted on the web.

As with all accelerated testing, it doesn't mean dip, if it doesn't well represent the end use environment. When that plane is screaming out of the sky and you're thinking about doing a face plant on the back of the head of the guy in front of you, waving a report touting the successful accelerated test program just doesn't seem to mean too much. You do not see any 'Comet' jet aircraft build by DeHaviland flying anymore.

While there's tons of stuff written, a good comparison study done by TI under TURI auspicisiis is: http://www.turi.org/content/content/download/1317/6190/file/Testing_and_Analysis_of_Surface_Mounted_Lead_Free_Solderin..pdf

We not convinced that all this matte tin qualification isn't just a smoke screen [butt covering] to gloss-over the lack of knowledge about the drivers to tin whiskers. NASA found tin whiskers on matte tin. Admittedly it was after 20 years, but they're still tin whiskers on matte tin, which is a world of difference from "bright" => whiskers / "matte" => no whiskers. Look here: http://nepp.nasa.gov/whisker/anecdote/20year/

There. Nice going. What a buzz killer. I've got to got find some donuts, cold pizza, er whatever.

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jim_bob

#29862

Matte tin finish | 5 August, 2004

Thanks. Yes, this is a interesting topic, and one that keeps our component engineers busy these days. I'm familiar with the data you referenced. Is there a "easy" method (test method) to use at incoming inspection to verify a termination is "matte" Sn?

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#29885

Matte tin finish | 5 August, 2004

Bright vs matte tin is fairly easy, but there's a s whole bunch of alternatives, beyond those two choices. So, no, not that we know.

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