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<tt>The article from </tt><tt><span style=""><font size="2">Beijing
University of Technology </font></span></tt><tt>was done July 2008.
The intent was to show it has been a noted problem for some time, from
the start, without a solution, and still a problem. Note how fast they
grow in some of the examples.<br>
<br>
Yes regular leaded solder does grow whiskers too but not at the speed
and length of lead free. Now, with circuits getting even smaller and
tighter it is a problem to address and be aware of. Once the circuit
shorts all sorts of havoc will be done. <br>
<br>
The quote you quote does say the phenomenon did not show up until
they started to reduce the lead content. In older electronics,
equipment was long declared obsolete and scrapped before such an event
would happen so it was never discovered. Old equipment was not worth
the trouble to repair. Why do you think they came out with silver
solder as used in Tektronics scopes?<br>
<br>
R</tt><tt>ead everything written before you speak..... I just hate it
when people don't read all of what you write. Stop trying to disprove
and learn. Noone know it all. I worked over 32 years at a big three
automotive R&E center as an electronics technician, just retired at
age 53. I do repairs on everything including surface mount. They
still are struggling with the whisker problem.</tt><br>
<tt><br>
I could add quite a brag line to my email but I do not think it shows
any class plus it has nothing to do with this.<br>
<br>
Electronics is just getting started, wait another 10 years and see what
comes! What a great hobby and what a great job it was!<br>
<br>
Shanon KA8SPW<br>
</tt><br>
Amir Findling K9CHP wrote:
<blockquote cite="mid:48F36529.2090703@gmail.com" type="cite">
<meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type">
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Well, checking out Shannon's cited source, it looks as if the reports
were from 1992 to 2002 with one single occurrence in 2005. Here is a
quote from that last source <a moz-do-not-send="true"
href="http://nepp.nasa.gov/whisker/reference/tech_papers/2005-dadonna-nuclear-reactor-shutdown.pdf">http://nepp.nasa.gov/whisker/reference/tech_papers/2005-dadonna-nuclear-reactor-shutdown.pdf</a><br>
<br>
"The tin whisker is a phenomenon the National Aeronautics and Space
Administration <br>
(NASA) has been tracking since the 1940s."<br>
<br>
Shannon, I may be the bearer of bad news, as the Drake TR4 having been
around since the mid-60's, I think it may also potentially suffer from
the same "fate"... <span class="moz-smiley-s2"><span> :-( </span></span><br>
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<ul type="disc">
<li class="MsoNormal" style="">73 de K9CHP Amir Findling, Member
ARRL, ARRL/ W5YI VE, WAC</li>
<li class="MsoNormal" style=""><a moz-do-not-send="true"
href="http://www.k9chp.net">www.K9CHP.net</a></li>
<li class="MsoNormal" style="">Senior K9 Handler</li>
<li class="MsoNormal" style="">K9 Certification Tester, NYS
Federation of SAR Teams</li>
<li class="MsoNormal" style="">1st Special Response Group (1SRG)</li>
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<br>
<br>
Shanon KA8SPW wrote:
<blockquote cite="mid:48F3451B.4010306@sbcglobal.net" type="cite">
<meta content="text/html;charset=ISO-8859-1"
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<tt>My fellow hams:<br>
<br>
Don't be so fast to replace what works. Another case of a law to
replace or reduce something before the technology is there to provide a
solution.<br>
<br>
Take a read about growing "tin whiskers" and lead free solder. Big
problem in RoHS circuits. And it don't take long to show up.<br>
<br>
"There is electrical risk posed by the other major component of solder,
tin. For reasons that remain somewhat obscure, tin used in electronic
devices can form what are called "<a moz-do-not-send="true"
href="http://nepp.nasa.gov/whisker/">tin whiskers</a>,"
thin filaments of the metal up to 10mm long that sprout from surfaces
covered in the metal. Although the causes of the whiskers are obscure,
the consequences aren't: whiskers that bridge two conducting areas can
cause short circuits, causing erratic behavior or ultimately destroying
the equipment. NASA <a moz-do-not-send="true"
href="http://nepp.nasa.gov/whisker/failures/index.htm">maintains a list</a>
of various military, orbital, and medical failures that have been
attributed to tin whiskers. Presumably, many failures in equipment that
is not significant enough to warrant a post-failure analysis are also
the product of tin whiskers."<br>
</tt><tt><br>
<br>
Notice how manufacturers are keeping quiet about this problem. In
some electronics it will take a while and then one day, smoke. Won't
be any rigs of today working say in 30 years like an old Drake TR4 does
today. I won't be buying anything lead free until the problem has been
solved for some time. <br>
<br>
Your millage may vary.<br>
<br>
Shanon KA8SPW<br>
<br>
<br>
Sites from the text above:<br>
<br>
"Tin Whiskers" <a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://nepp.nasa.gov/whisker/">http://nepp.nasa.gov/whisker/</a><br>
<br>
"NASA Maintains a list" <a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="http://nepp.nasa.gov/whisker/failures/index.htm">http://nepp.nasa.gov/whisker/failures/index.htm</a><br>
<br>
The article bellow has pictures with time taken to grow the whiskers in
different enviroments. <br>
<p style="margin: 0pt; line-height: 100%; text-indent: 0pt;"
align="left"><font size="3"><b>July 2008</b> </font>- Tin whiskers on
<u><span style="font-size: 12pt; font-family: Arial;"><i style=""><b
style="">Sn-3.8Ag-0.7Cu-1.0Ce/Er/Y </b></i><b
style="font-size: 12pt; font-family: Arial;"><i
style="font-size: 12pt; font-family: Arial;">S</i></b><b style=""><i
style="">older </i></b><i style="font-size: 12pt; font-family: Arial;"><b
style="font-size: 12pt; font-family: Arial;">J</b></i><b style=""><i
style="">oints</i></b></span></u> </p>
<!--mstheme--></tt><!--msthemelist--><!--msthemelist-->
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<tbody>
<tr>
<td valign="baseline" width="42"><tt><img
src="cid:part1.08090100.05040103@sbcglobal.net" height="12" hspace="15"
width="12"></tt></td>
<td valign="top" width="100%"><!--mstheme--><tt> </tt>
<p style="margin: 0pt; line-height: 100%; text-indent: 0pt;"
align="left"><tt><span style=""><font size="2"><a
moz-do-not-send="true"
href="http://nepp.nasa.gov/whisker/other_whisker/SAC/2008-Hao-whiskers-SAC-Ce-Er-Y-solder.pdf"><b
style="">"</b></a><a moz-do-not-send="true"
href="http://nepp.nasa.gov/whisker/other_whisker/SAC/index.htm"><b
style="">Tin Whiskers with Special Morphology<o:p> </o:p> </b><b
style="">"</b></a>, H. Hao, Y. Shi, Beijing University of Technology,
July 2008</font></span></tt></p>
</td>
</tr>
</tbody>
</table>
<tt> <a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://nepp.nasa.gov/whisker/other_whisker/SAC/index.htm">http://nepp.nasa.gov/whisker/other_whisker/SAC/index.htm</a><br>
<br>
</tt><br>
<br>
Bernard Tyers wrote:
<blockquote
cite="mid:85B200CB-C2EE-4817-8FFC-F6461D2C76F9@ei8fdb.org" type="cite"><br>
On 13 Oct 2008, at 07:29, Arno Verhoeven (PE1ICQ) wrote: <br>
<br>
<blockquote type="cite"><br>
and believe it or not... China has come up with their own set of RoHS <br>
requirements. <br>
<br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://www.chinarohs.com/">http://www.chinarohs.com/</a> <br>
</blockquote>
<br>
<br>
"It's not Just Another RoHS. It's CHINA RoHS!" <br>
<br>
This is a joke? Yes? I wonder if they will have a RoHS rating for
Bindeez beads.. <br>
<br>
I, for one, am glad that the EU (one of the good things they have done
recently) are removing Pb from solder. The one time I had to get myself
near a large scale soldering/manufacturing station it wasn't pleasant.
And I was there only for a few weeks. <br>
<br>
Now, if we can make some head way on other poisonous chemicals
(mercury, PVCs, flame retardents) it would be even better. <br>
<br>
regards and 73, <br>
bernard/ei8fdb<br>
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