But Cassini is a bunch of years old, at least 10 I think. The components are most likely plated leads on diodes or tin canned pots.
Pat
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Dale Ritzen
Sent: Tuesday, March 20, 2012 11:00 AM
To: [log in to unmask]
Subject: Re: [TN] Out of the world tin whiskers
Joyce,
I know your question below is basically rhetorical, but have you tried to find a component without a Pb-free coating on it lately... That is, unfortunately, why there are Pb-free components on spacecraft... and obviously tin whiskers.
Dale Ritzen, CQA
Quality Manager / ISO Management Representative Austin Manufacturing Services
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo
Sent: Tuesday, March 20, 2012 12:57 PM
To: [log in to unmask]
Subject: Re: [TN] Out of the world tin whiskers
I thought space is exempt for leadfree. Why?
--------------------------
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----- Original Message -----
From: Inge Hernefjord [mailto:[log in to unmask]]
Sent: Tuesday, March 20, 2012 01:47 PM
To: [log in to unmask] <[log in to unmask]>
Subject: Re: [TN] Out of the world tin whiskers
DO THEY NEVER LEARN!
Inge
On 20 March 2012 18:08, Gervascio, Thomas L <[log in to unmask]>wrote:
> Tin whiskers at Saturn
>
> PASADENA, Calif. -- The Cassini plasma spectrometer instrument (CAPS)
> aboard NASA's Cassini spacecraft at Saturn has resumed operations.
> Mission managers received confirmation on Friday, March 16, that it was turned on.
> They plan to monitor the instrument for any unusual behavior.
> Last June, short circuits in the instrument led to unexpected voltage
> shifts on the spacecraft. As a precaution, mission managers turned off
> the CAPS instrument while engineers investigated the issue. The
> investigation led to the conclusion that tin plating on electronics
> components had grown "whiskers." The whiskers were very small, less
> than the diameter of a human hair, but they were big enough to contact
> another conducting surface and carry electrical current. Researchers
> are still trying to understand why whiskers grow on tin and other
> metals, but they know now that whiskers can grow in space and on
> Earth. It is believed that these or additional tin whiskers that may
> grow on Cassini cannot carry enough current to cause problems, but will burn out on their own like a lightweight fuse.
>
>
>
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