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March 2012

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Subject:
From:
Inge Hernefjord <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Inge Hernefjord <[log in to unmask]>
Date:
Wed, 21 Mar 2012 23:07:18 +0100
Content-Type:
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text/plain (255 lines)
The first tin whisker report came 1954.  Already covered most you need to
know!! I have a copy if someone want.

Inge

On 21 March 2012 22:51, David D. Hillman <[log in to unmask]>wrote:

> Hi Bob - Outstanding! I anticipate an informative  presentation on the
> situation as the NASA group always has great information.
>
> Dave
>
>
>
> Bob Landman <[log in to unmask]>
> Sent by: TechNet <[log in to unmask]>
> 03/21/2012 10:45 AM
> Please respond to
> Bob Landman <[log in to unmask]>
>
>
> To
> <[log in to unmask]>
> cc
>
> Subject
> Re: [TN] Out of the world tin whiskers
>
>
>
>
>
>
> Hi Dave,
>
> Henning Leidecker has confirmed to me that his group (Henning, Jay and
> Lyudmyla) at NASA Goddard SFC was on the committee that that determined
> the problem was indeed tin whiskers.
>
> Bill Rollins has offered Henning the opportunity to present their findings
> to our weekly tin whiskers teleconference. Hopefully we'll hear about it
> soon.
>
> Bob Landman
> LDF Coatings, LLC
> www.ldfcoatings.com
> H&L Instruments, LLC
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
> Sent: Tuesday, March 20, 2012 6:15 PM
> To: [log in to unmask]
> Subject: Re: [TN] Out of the world tin whiskers
>
> Hi Pat and gang - good information as our "industry attention" on the
> topic of tin whiskers pre-1997 was not at the same level of scrutiny as we
> have today. This failure, if it has a tin whisker root cause, is a
> demonstration of two things: (1) the breakdown of system rules prohibiting
> the use of pure tin in a space application.  NASA has always attempted to
> avoid the use of pure tin due to the tin whisker risk. There may have been
> a simple human error or this could have been a lack of knowledge by a
> supplier; (2) the lack of a tin whisker mitigation strategy. If there was
> going to be the use of pure tin in a space application, was a tin whisker
> mitigation methodology missed - such as pretinning the leads, adequate
> design spacing or the use of a coating material to capture/contain the
> whiskers?  Easy to second guess what happened. Hopefully, further details
> of the story will be published so that we can learn from the issue.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
>
>
>
> "Goodyear, Patrick" <[log in to unmask]>
> Sent by: TechNet <[log in to unmask]>
> 03/20/2012 02:33 PM
> Please respond to
> TechNet E-Mail Forum <[log in to unmask]>; Please respond to
> "Goodyear, Patrick"     <[log in to unmask]>
>
>
> To
> <[log in to unmask]>
> cc
>
> Subject
> Re: [TN] Out of the world tin whiskers
>
>
>
>
>
>
> To answer my own question.
>
> Cassini was launched October 15,1997, so it was most likely built in
> '96-'97 timeframe.  I don't think lead free had hit the streets by then
> except for applications in plumbing.  Whiskers had been an issue long
> before that, at least in my industry.   We have been inspecting for them
> since around 1992, we tripped a unit in 1988 due to a whisker in a relay,
> shorting out a contact that should have opened when the relay energized.
>
> pat
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Goodyear, Patrick
> Sent: Tuesday, March 20, 2012 11:11 AM
> To: [log in to unmask]
> Subject: Re: [TN] Out of the world tin whiskers
>
> 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?
> --------------------------
> Sent using BlackBerry
>
>
> ----- 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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