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Re: lead free solder again


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the

Is it possible to buy an insurance against such warranty disasters?
Make it a book keepers problem.

What about conformal coating? Not a bad idea anyway, for industrial
circuit boards.

--
Thanks, Frank.
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Re: lead free solder again




Frank Bemelman wrote:

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I see you're one of those 'cost isn't an issue' guys !

Bloody typical.

Graham


Re: lead free solder again


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The
of
shitloads

It's true that costs were never my first priority. But if tin wiskers
is what worries you, I though that coating is perhaps something that
make you sleep better at night. You can save a few nickles if you
only coat the edges of your TQFP's with coating.

Anyway, you have the choice.

--
Thanks, Frank.
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Re: lead free solder again




Frank Bemelman wrote:

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For what I do, I'm more interested in poor joint durability.

Graham


Re: lead free solder again



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   Coating will *not* solve the problem; it is *not* reliable.
   Hell, clean the surface like crazy, anneal it like crazy and put it
in the vacuum of outer space, and you *still* can get tin whiskers!

Re: lead free solder again



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How about if it's plated with something like nickel, or chrome, or moly?

Thanks,
Rich



Re: lead free solder again


[....]
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Conformal coating is a horrid idea.  Put the circuit boards in a housing
that protects them.  From what I've seen coating just adds another way to
screw up.

--
--
snipped-for-privacy@rahul.net   forging knowledge


Re: lead free solder again


On Wed, 12 Jul 2006 23:59:22 +0200, "Frank Bemelman"

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Even if you could find someone crazy enough to insure against tin
whisker failures, it is actually a company reputation problem. That
can lead to lost sales or being excluded from the market. Disastrous
for small companies!

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Our boards are in a hermetically sealed package that can withstand a
few hundred bars of pressure. Conformal coating only provides added
costs and repair hassles for us.
Can whiskers penetrate thru a polyurethane conformal coat?

---
Mark

Re: lead free solder again


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Disastrous for large companies as well. We're all in the same
boat.

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The cost is peanuts, if you already have an expensive sealed
package. And anything decent doesn't need repairs.

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I'd say no. That whole whiskers argument is just a convenient
blame target.

--
Thanks, Frank.
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Re: lead free solder again


Hello Frank,

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Peanuts? On a board in a cheap consumer device that has numerous rubber
switch pads that must be masked?

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Did you try and monitor for 10-15 years?


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Err, I don't think so.

--
Regards, Joerg

http://www.analogconsultants.com

Re: lead free solder again



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FB obviously has no clue and won't be told!!!



Re: lead free solder again




ian field wrote:

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He's exhibiting a dangerous case of  'they must know what they're doing' !

Graham



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Someone expressed some concerns about TQFP's. I suggested
applying some coating on the legs. With a brush. And I don't
expect to find a PCB with rubber pads in a hermetically sealed box.

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No, but I didn't try deep frying ice cubes either.

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Yep, whiskers are growing everywhere these days. If they
don't cause a short circuit, they will jam the cooling
fan. When they have grown long enough, you can harvest
them and knit a nice tie from it. Sheesh.

--
Thanks, Frank.
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Re: lead free solder again



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   You ae incorrect; coatings are unreliable - sometimes they work and
sometimes they do not; and the longer one needs reliability, the lower
the chances of success.

Re: lead free solder again



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Whiskers will poke right through conformal coat right above where they are
initiating from, but they have difficulty poking back through the conformal
coat.  Also, the conformal coat yields additional protection from whiskers
that have broken off and are just wandering around.




Re: lead free solder again


Hello Ken,

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And then it's "whisker meets whisker". Bzzzt .... poof.

--
Regards, Joerg

http://www.analogconsultants.com

Re: lead free solder again


On Sat, 15 Jul 2006 00:12:07 GMT, Joerg

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My cure for microscopic whiskers/pin-holes on thick film boards...
6V/300A power supply ;-)

                                        ...Jim Thompson
--
|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Re: lead free solder again


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are
conformal
whiskers

Look at the bright side. Most adjacent whiskers are on the
same net ;)

The downside is, that it can even endanger other equipment
that uses lead solder. Imagine whiskers growing out of
your RoHS compliant equipment, entering the ventholes of
your older non-RoHS stuff. Another KABOOM waiting around
the corner...

LOL

--
Thanks, Frank.
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Re: lead free solder again



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What a pity you mock those who actually know what they're talking about! - I
hope your TV gets whiskers and burns your house down, then you might not be
so free and easy with the sarcastic remarks!



Re: lead free solder again


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they
I
be

Yes, I seriously doubt what Joerg is talking about. And myself, for that
matter. But I am confident about my next TV - those manufacturers do know
what they are dealing with, and I don't hear them complain.

But, even you would have to admit that most adjacent whiskers are on
the same net. So even if they do emerge, most of them will be pretty
harmless. The more I'm thinking about it, applying some coating on
the edges of TQFP's isn't such a crazy idea. At least it *is* an
idea. All I hear from Joerg is complaining about something he has
zero hands-on experience with.

--
Thanks, Frank.
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