Hi Inge!
Yep, ready as I'll ever be. Have your *.doc posted. It's at:
http://stevezeva.homestead.com/For_TN_jan012.doc
Them be some big whiskers!
That puppa doggie that you saw is "Sir Andrew", or Andy as he's normally
known:
http://stevezeva.homestead.com/Me_and_Andy.JPG
He actually belongs to my niece and her husband. I get to see him when I go
back to North Carolina to visit.
Problem with "Sir Andrew" is that in his mind he thinks he's a little lapdog
like a Chihuahua or something, but as you see he's the size of a small
horse.
But he's a very lovable dog, and he's always happy to see me each and every
time I come to visit. I wouldn't wanna have his food bill tho'! :o)
Steve
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge
Sent: Monday, January 23, 2012 4:12 PM
To: [log in to unmask]
Subject: Re: [TN] Finally, the folly of lead-free solder is making the big
time
I've lots of photos on tin whiskers from my time as special analyst. I'll
send some photos that may interest (and frighten you) you, namely from a
microwave waveguide. The flange was tin 100% tin plated om inside and not
surprising, the inside of the waveguide became covered by zillions 1-10 mm
long whiskers. We noticed them on the return wave, hardly detectable because
of the outgoing wave was 10 dbm lower. And the power loss, what became of
the that? Internal heat.. So no warming hotdogs in front of the horn those
days.
Steve, are you ready?
Guys, have you seen Steve's dog. Bigger than Steve himself! 10 hotdogs won't
be enough for that dog's breakfeast-
Inge
----- Original Message -----
From: "Goodyear, Patrick" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, January 23, 2012 7:47 PM
Subject: Re: [TN] Finally, the folly of lead-free solder is making the big
time
Well I agree in both cases.
We inspect all of our equipment on a rotating periodic basis (every 2 years)
for whisker formation. When Our Supplier first issued the bulletin on
whisker formation almost 20 years ago we have found numerious instances of
whisker formation on tin plated leads and components. The largest I have
found was possibly 34Ga and almost 3/4" long on a tin plated pot on a
voltage regulator for a 48V 25amp supply, one of it's bretheren took out the
voltage regulator board with catistrophic results. The rest of the two
pots looked like they had hair growing on them. Our supplier recommended
we install rubber heat-shrink boots on the pots, it did somewhat retard
formation. All of these components are late 1960's early 1970's vintage so
contain 60/40 solder for the most part and not 63/37. I do find after 2
years, growth on diode leads of around 1-2mm. We inspect every high
reliability component under at least 10X, and then 40X when we find a
potential issue, we document then remove the problem.
Pat
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Monday, January 23, 2012 9:01 AM
To: [log in to unmask]
Subject: Re: [TN] Finally, the folly of lead-free solder is making the big
time
Whiskers can be produced by several different types of alloys, including
lead, silver, tin, and zinc. The most common (in electronics) are tin and
zinc.
The whiskers typically take on characteristics of the metal they are borne
from. For example, zinc and tin whiskers are usually straight, brittle, and
break easily. Tin whiskers are shiny and do not usually branch out, but zinc
whiskers often produce many branches and are black or dark gray in color.
Lead whiskers, on the other hand, are curly, soft, malleable, and are
fragile but can withstand some bending forces before they break.
Our Technet friend Ingemar Hernefjord once posted some incredible lead
whisker photos, I believe they are in Steve Gregory's website. I think this
is one of them. http://stevezeva.homestead.com/files/daniel121b.jpg
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of harvey
Sent: Monday, January 23, 2012 10:36 AM
To: [log in to unmask]
Subject: Re: [TN] Finally, the folly of lead-free solder is making the big
time
Thanks.
Tin, wherever used, may form whiskers.
The list of sources would include tin plating anywhere, lead free solder,
and 63-37 solder.
But I believe that lead deters whisker formation in eutectic solder
generally.
That is a statement that is supported by empirical history and much more.
I'm copying Carol Handwerker for her opinion on the subject.
--- On Mon, 1/23/12, Julie Silk <[log in to unmask]> wrote:
From: Julie Silk <[log in to unmask]>
Subject: Re: [TN] Finally, the folly of lead-free solder is making the big
time
To: [log in to unmask]
Date: Monday, January 23, 2012, 8:10 AM
These weren't soldered with lead-free
solder. It was tin-lead. The problem was tin-plated parts or boards (maybe
both?).
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