OT: tin whiskers videos

[DOUGLAS ZWIEBEL]

Although the NASA site was already cited by W8UR, I thought "just in
case" anyone didn't navigate around the NASA page, that I would post
the NASA video link.

http://nepp.nasa.gov/whisker/video/index.html

Video #10 is amazing (and narrated).  There is even one video (#3)
showing tin whiskers on a 1960 Grundig radio.  Amazing.

de Doug KR2Q
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[DOUGLAS ZWIEBEL]

I posted this back in Oct, 2007, but since the topic has come up
again, well, here it is again.

Of note is that in NASA video #10, it indicates that tin whiskers were
found that were up to 1.8cm long (7/10th inch)...a long way from "a
few mils" recently cited.

de Doug KR2Q


---------- Forwarded message ----------
From: DOUGLAS ZWIEBEL <[hidden email]>
Date: Sat, Oct 20, 2007 at 8:58 AM
Subject: OT: tin whiskers videos
To: [hidden email]


Although the NASA site was already cited by W8UR, I thought "just in
 case" anyone didn't navigate around the NASA page, that I would post
 the NASA video link.

 http://nepp.nasa.gov/whisker/video/index.html

 Video #10 is amazing (and narrated).  There is even one video (#3)
 showing tin whiskers on a 1960 Grundig radio.  Amazing.

 de Doug KR2Q
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[Brett Howard]

Thats also in much different conditions than what you'll find in most
electronics.  But OK since NASA said so all electronic products from now
until eternity are destined to short themselves out and fail nasty
horrible deaths.  Oh no what shall we ever do!


On Sun, 2008-04-06 at 07:06 -0400, DOUGLAS ZWIEBEL wrote:

> I posted this back in Oct, 2007, but since the topic has come up
> again, well, here it is again.
>
> Of note is that in NASA video #10, it indicates that tin whiskers were
> found that were up to 1.8cm long (7/10th inch)...a long way from "a
> few mils" recently cited.
>
> de Doug KR2Q
>
>
> ---------- Forwarded message ----------
> From: DOUGLAS ZWIEBEL <[hidden email]>
> Date: Sat, Oct 20, 2007 at 8:58 AM
> Subject: OT: tin whiskers videos
> To: [hidden email]
>
>
> Although the NASA site was already cited by W8UR, I thought "just in
>  case" anyone didn't navigate around the NASA page, that I would post
>  the NASA video link.
>
>  http://nepp.nasa.gov/whisker/video/index.html
>
>  Video #10 is amazing (and narrated).  There is even one video (#3)
>  showing tin whiskers on a 1960 Grundig radio.  Amazing.
>
>  de Doug KR2Q
> _______________________________________________
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>
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[Ken Kopp-3]

These conductive "growths" from metal plating were a
-severe- problem for early versions of GE 2-way radio's
MASTR II (sic) series of radios. The plated cavities that
held the tuned circuits for the RF front ends grew almost
invisible whiskers off the walls of the housing that were
astoundingly strong.

73! Ken Kopp - K0PP
       [hidden email]

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[k7svv]

Back in the late 60's IBM was almost brought to its knees by a problem with
silver migration (whiskers) in its flat cable connectors.  This happened
primarily in their System 360 Models 50 and 65 mainframes.  It cost the
company many millions of dollars because every Model 50 and 65 plus some
others had to have every flat cable replaced.  Each machine had a LOT of
cables, I can't even guess how many.  It took teams of 5 people working
around the clock 2 days to recable a Model 50.  Them were the good old days.
The Model 50 made me a lot of money over the years.  73

John    [K7SVV]

----- Original Message -----
From: "Ken Kopp" <[hidden email]>
To: <[hidden email]>
Sent: Sunday, April 06, 2008 8:28 AM
Subject: [Elecraft] OT - Tin whiskers

> These conductive "growths" from metal plating were a -severe- problem for
> early versions of GE 2-way radio's MASTR II (sic) series of radios. The
> plated cavities that held the tuned circuits for the RF front ends grew
> almost invisible whiskers off the walls of the housing that were
> astoundingly strong.
>
> 73! Ken Kopp - K0PP
>       [hidden email]
>
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>
>
> --
> No virus found in this incoming message.
> Checked by AVG. Version: 7.5.519 / Virus Database: 269.22.8/1362 - Release
> Date: 4/6/2008 11:12 AM
>
>

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[KC5CQW]

 <quote author="Brett Howard">
Oh no what shall we ever do!

    In the aerospace industry, we use "conformal coatings". On one of the jobs I did, Humiseal was used.
It was a spray can of an acrylic formulation that could be removed with acetone if rework is needed.
This is desirable because the others are not removable without a hammer and chisel!
Humiseal also has an "optical enhancer". It is very visible under a UV lamp.
That way it is easy to tell if the pc board is coated corectly or if the Humiseal was removed completely.

     Note: Humiseal WILL CLOG A VACUUM SOLDER SUCKER!!! Not that I know from experience or anything... Be sure to remove it completely in case of rework.
If used, be sure to mask off all connectors, pots and other variable what-knots.
This stuff will ALMOST make the PC board water-proof. Avionics have to pass many environmental tests before shipping to the customer. This includes <-30deg F with condensation, i.e., frost.

     So why would I post this in a topic about tin whiskers? Because I've NEVER seen a PC board with tin whiskers that was conformally coated! I may be wrong but, this is my observation.

I have nothing to do with Humiseal, tin, solder or PC board industries or companies...