How Tin-Whiskers Form

[VK1OO, Mike Walkington]

All,

Over the years there has been the odd thread about "tin-whiskers", so
the following may be of interest.

http://phys.org/news/2012-12-doctoral-student-unravels-tin-whisker.html


Mike
VK1OO
K2#2599
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Vic Rosenthal]

Fascinating, as are the comments following the article. The removal of metallic lead from
electronics that should be recycled anyway, in return for a large increase in failures,
does not seem to me to be a good deal for civilization (some of the comments mentioned the
removal of lead from gasoline, which in contrast was a very good decision).
There should be a name for the irrational fear of tiny quantities of substances that would
be harmful only in large amounts -- like RF, to give another example.
No, I will not answer outraged personal emails on this subject!

On 12/10/2012 1:08 AM, VK1OO wrote:

> All,
>
> Over the years there has been the odd thread about "tin-whiskers", so the following may
> be of interest.
>
> http://phys.org/news/2012-12-doctoral-student-unravels-tin-whisker.html
>
>
> Mike
> VK1OO
> K2#2599
>

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[N2TK]

As a manufacturer of space discrete devices, we use lead in all of our
solder. It is a requirement to help suppress the growth of tin whiskers. To
date, no one has come up with an alternative to lead.   We keep trying to
find an alternative. So, no we are not RoHS compliant. All satellite
companies world-wide require lead in the solder.

73,
N2TK, Tony

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Vic K2VCO
Sent: Monday, December 10, 2012 11:05 AM
To: [hidden email]
Subject: Re: [Elecraft] How Tin-Whiskers Form

Fascinating, as are the comments following the article. The removal of
metallic lead from electronics that should be recycled anyway, in return for
a large increase in failures, does not seem to me to be a good deal for
civilization (some of the comments mentioned the removal of lead from
gasoline, which in contrast was a very good decision).
There should be a name for the irrational fear of tiny quantities of
substances that would be harmful only in large amounts -- like RF, to give
another example.
No, I will not answer outraged personal emails on this subject!

On 12/10/2012 1:08 AM, VK1OO wrote:

> All,
>
> Over the years there has been the odd thread about "tin-whiskers", so
> the following may be of interest.
>
> http://phys.org/news/2012-12-doctoral-student-unravels-tin-whisker.htm
> l
>
>
> Mike
> VK1OO
> K2#2599
>

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[aj4tf]

The fact that stress gradients appear to propagate tin whiskers has been known for some time.  (in fact, the phys.org authors should have researched their own web site more thoroughly:   http://phys.org/news173450615.html#nRlv)

At my place of employment, we also are concerned about the impacts of RoHS parts (RoHS = non-lead-bearing) and their impact to long term reliability of electronic assemblies.  We don't make things that go into space, but we make things that are nearly equally inaccessible once they are installed.  Recently we performed an experiment on an assembly to attempt to induce tin whisker formation by temperature cycling it hundreds of times over the course of over 6 months.  At the end of the experiment, only one component (out of hundreds on the assembly) showed any signs of whisker formation.   Even with RoHS parts, using lead-based solder paste to assemble the boards partially (but not completely) mitigates the risk.

David AJ4TF