So what's the truth about lead-free solder ? - Page 13

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Re: So what's the truth about lead-free solder ?
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Perhaps is right.

There are no people as conservative as the safety case folks in avionics
safety critical systems. They will want 20 years worth of data because
that is the typical lifetime of a system once installed in the civilian
market.

Cheers

PeteS

Re: So what's the truth about lead-free solder ?
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Or their kid's game console stops working; wait - that's already
happening ;)

Cheers

PeteS

Re: So what's the truth about lead-free solder ?
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tin
white tin
powder,

So when I pull , with just finger tension, a component lead through what was
a lead-free solder joint only a year or so before and there is a grey
powdery looking surface to the lead where it had been inside the solder
joint - is that "tin pest" ?


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
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Re: So what's the truth about lead-free solder ?



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It could well be I suppose. Here's the problem, we're in 'uncharted territory'
here because the EU insisted on going down this path before the science was
well-established. Document it. It has serious implications for the classic
practice of keeping MI gear in the van / truck, in the (unheated) garage etc.

I'd love to see the idiots at the Commision in Brussels forced to eat humble
pie. It's about time that Emperor Barroso's new clothes were seen for what they
are.

Graham


Re: So what's the truth about lead-free solder ?
On Wed, 25 Jul 2007 19:03:35 +0100, Eeyore

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  That's what cost Napoleon dearly in Russia.  He lost his armies to
exposure due to their uniforms literally falling off their bodies.

 All Tin buttons, even on their boots.

http://ds.dial.pipex.com/town/terrace/adw03/c-eight/france/moscow.htm

Re: So what's the truth about lead-free solder ?



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tin
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Oh, I recall it now.

It seems that the Open University has studied this issue and has indeed found tin
pest in 'cheap' lead-free solders that are 99%+ tin. These are in commercial use
too
!

http://materials.open.ac.uk/srg/srg_tp.htm

The question next should be whether the popular SAC alloys are affected.

Graham



Re: So what's the truth about lead-free solder ?
On Thu, 26 Jul 2007 06:18:27 +0100, Eeyore

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  I didn't read that cite I posted a link to well enough.  It barely
mentions it.


http://ap.pennnet.com/Articles/Article_Display.cfm?Section=Articles&Subsection=Display&ARTICLE_ID21%6209

Re: So what's the truth about lead-free solder ?
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The main issue for lead free in military and aerospace electronics is
tin whiskers. Tin solder will
grow conductive whiskers that even penetrate conformal coatings. In
low power circuit,
the whisker will short something out. In a high power circuit, it
might burn up like a fuse,
but if it happens in a satellite (no atmospheric pressure) the little
whisker will cause
a plasma arc capable of passing huge amounts of current.

We in the defense electonics industry fight with this issue every day
and the information
is very confusing. Parts turn lead free midstream in production and
seems impossible to
keep tack of it. Every company is dealing with it differently. We stay
away from certain
finishes like bright tin and look at the spacing of components and
coatings on our boards.
This can mitigate some of the reliability risks of lead free.

If high-rel is of upmost importance, we struggle to find tin-lead
parts.


Re: So what's the truth about lead-free solder ?

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That's worrying ...

Arfa



Re: So what's the truth about lead-free solder ?
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I'm currently consluting in the aerospace / military equipment area and
this place goes to the length of re-balling BGAs with eutectic tin-lead
solder, clearing and refinishing pins etc. - i.e. if it's not the right
finish, the company refinishes the part.

There are some non SnPb finishes that are ok in non-safety critical
systems, but safety critical (flight control computers, FADECs etc) must
have a tin-lead solder profile. Gets to be a real problem with small
passives.

Pushes up the price of everything, of course.

Cheers

PeteS



Re: So what's the truth about lead-free solder ?



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The effort invoved in puting lead back on components always strikes me as one of
the more bizarre aspects of RoHS. Talk about proof the idea was fundamentally
wrong in the first place !

Graham


Re: So what's the truth about lead-free solder ?

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Seconded on that, and a point that I've been making since the start in the
various scribblings I've done for the trade rags etc.

Arfa



Re: So what's the truth about lead-free solder ?
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Got to agree. My view is it was pushed for a political agenda rather
than a scientific one (duh) and a reduction in hazardous substances has
not and will not be achieved from the directive. There are more
hazardous chemicals used (by volume) for the replacement processes than
is removed by the RoHS directive, amusingly. Another issue is because of
the suspect reliability of equipment (there definitely seems to be more
failures in RoHS compliant products), more equipment is actually made.
With the WEEE directive it simply means that more parts are used, and
the costs go up due to the cost of dealing with / recycling defective
equipment. Doesn't make much sense, really.

On the refinishing front, if we could buy SnPb finished parts, we would.
These are still available directly from manufacturers of some parts for
the aerospace industry, but not from others. Having two processes drives
up their costs, so we either pay the manufacturer for it or pay our own
facilities for it. Either way, the end product cost increases.

If the object of the exercise was to reduce hazardous substances, it has
failed spectacularly.

Cheers

PeteS

Re: So what's the truth about lead-free solder ?

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   I do not know if the term "amusingly" is appropriate.

  I don't know if I would ever describe a failure of any kind as being
"spectacular" either.

  The term miserably comes to mind in both instances, as that is exactly
what it has caused nearly all involved.

  Hopefully, said misery will come full circle, and bite the politicians
that started this CRAP right in the ass.  It will certainly have an
economic impact, and they will likely find some way to squirm clear of
any blame, but the fact remains, that there was no science involved, and
that technically we already knew about this decades ago when our REAL
scientists formulated the solders we now know for a fact to be superior
in all respects.

Re: So what's the truth about lead-free solder ?
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one of
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Amusing does not need to be 'funny' - it's more sarcastic in this sense.
Spectacular, likewise, does not need to imply something good - merely
that the failure of the directive to achieve it's aims was not merely
'fail', but a very impressive fail.

I personally hope it comes back to bite the politicians (and there are
good reasons it might), but most of them are either teflon covered or
have safely retired.

Cheers

PeteS

Re: So what's the truth about lead-free solder ?



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I'd like to see Emperor Barroso humiliared over something for sure.

Graham


Re: So what's the truth about lead-free solder ?

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More than political -- the subject could easily be viewed as troll bait.
It's been 'discussed' many times in ser.

  http://tinyurl.com/22c6t


Re: So what's the truth about lead-free solder ?



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as
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data.
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It's not a troll.

New data ought be available as to the effects on actual in-service reliability of
lead-free by now. It seems as I expected, anecdotally, that musical equipment
products that tend to see high levels of vibration are suffering.

Graham


Re: So what's the truth about lead-free solder ?

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As are most other products that are *not* subject to excessive amounts of
vibration.

Arfa



Re: So what's the truth about lead-free solder ?
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data.
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of
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This subject came back to bite me yet again today. There's a great part
I wanted to use, but we'll have to refinish the pins first if I do, so
I'll see if there's a different part I can use in this application. For
the record, it's a high speed (not full speed) USB peripheral controller
and the lead finish is 98/2 SnCu.
I consulted with a few of the manufacturing people and one of the
biggest problems with RoHS profiles is the solders aren't eutectic, so
getting a proper bond is more difficult quite apart from the problem
with tin whiskers.

Cheers

PeteS

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