Lead free solder - exposed in a UK national newspaper

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http://www.guardian.co.uk/technology/2008/apr/03/research.engineering

Within a whisker of failure

Removing lead from solder may seem a smart idea environmentally, but the
resulting microscopic growths called tin whiskers could be just as
problematic

    * Kurt Jacobsen
    * The Guardian,
    * Thursday April 3 2008
    * Article history

This article appeared in the Guardian on Thursday April 03 2008 on p1 of the
Technology news & features section. It was last updated at 00:05 on April 03
2008.
Tin whiskers

On April 17 2005, the Millstone nuclear generating plant in Connecticut shut
down when a circuit board monitoring a steam pressure line short-circuited.
In 2006, a huge batch of Swatch watches, made by the eponymous Swiss
company, were recalled at an estimated cost of $1bn (500m). In both cases,
"tin whiskers" - microscopic growths of the metal from soldering points on a
circuit board - were blamed for causing the problems.

It's not the first time these mysterious growths have been blamed for
electronics failures. In 1998 the Galaxy IV communications satellite
sputtered out after just five years; engineers diagnosed its failure as due
to "whiskers".

The US military blamed them for malfunctioning F-15 radar systems and
misguided Phoenix and Patriot missiles. In 1986, the US Food and Drug
Administration recalled a number of pacemakers because of these same
whiskers. In fact, they've been known about since the 1940s, and happen with
cadmium and zinc, too: during the second world war, similar whiskers would
short the cadmium tuning capacitors in aircraft radios. A decade later,
tin-based relays in AT&T telephone switching centres were found to cause
shorts.


The solution to "whiskering"? Mix lead into the solder, as was done from the
1950s. Colin Hughes, a physicist who worked on the first British nuclear
bomb, told me that the whiskering problem never came up during his career.

But now the lead is gone, by legal mandate, and whiskers are back - causing
potential problems for us all.

Since 2006, lead has been banned from solder in the European Union under the
2003 Reduction of Hazardous Substance (RoHS) directive, which gave
manufacturers three years to phase out lead.

The logic seemed reasonable. Removing lead from petrol (where it was used to
prevent engine mistiming) brought clear environmental and health benefits,
taking a harmful chemical that can affect intelligence out of the
atmosphere. Removing lead from solder, the 37% lead, 63% tin alloy used to
join metal objects in everything from plumbing to circuit boards, was an
obvious next step to prevent it leaching into ground water from dumped items
in landfills.

Meanwhile, the US and Japan have also been moving to lead-free solders. It's
a huge shift; the US Environmental Protection Agency (EPA) estimates that
80m kilograms of lead solder was used worldwide in 2002. Environmental
groups have applauded the move. "In the US we've been surviving without lead
solder for many years," says Rick Hind, legislative director of Greenpeace's
toxics campaign. "With less exposure to lead we will all benefit by being
smarter and making safer and more durable products." (The US has not made
lead-free solder obligatory, but does offer tax benefits for doing so.)

But without lead to tame it, tin behaves oddly on circuit boards. Left
alone, tin plating, like cadmium and zinc, spontaneously generates
microscopic shreds of metal - about one to five microns in diameter, or less
than one-tenth as wide as a human hair - which push up from the base. If
they grow far enough to touch another current-carrying location, they'll
cause a short that can wreck the equipment while leaving barely any trace.

The cause is becoming clearer. "I believe the mechanism of whisker formation
is now understood: it is due to compressive stress - caused by, say,
diffusion of copper into the tin - being built up in the tin layer which
breaks through the tin oxide barrier layer [to the air]," says Steve Jones
of Circatex, in South Shields. Critics cite reports that solder
substitutes - pure tin, tin-zinc, tin-silver-copper - simply cannot match
the lead mixture for reliability, coverage ("wetting" terminals), and cost
(silver is especially pricey). Therefore, the US military, Nasa and medical
and high-level research equipment are exempt from what authorities view as
untrustworthy commercial components.

"I still use lead-tin solder - it works better," says John Ketterson, a
solid state physicist at Northwestern University in Illinois. He notes the
tradeoffs of "cost, materials, strength of the solder and all that" during
this mandated changeover, and that manufacturers "have to get an experience
base" with new processes.

{ snipped as lengthy }

Tin whiskers: coming to a PC near you?

They can grow at ambient temperature and humidity, or in vacuum

They can grow in steady or varying temperatures (though the latter may
encourage growth)

Whiskers' tips are atom-sharp. They will push through any coating, given
time

They are a prevalent cause, only now being identified, of many past
equipment failures

One whisker can carry about 30mA - more than enough to cause havoc in
digital circuits

Silver-tin-copper ("SAC") solder slows but doesn't stop whisker growth

SAC solder has more environmental impact than the lead-tin version

Older 37%-63% lead-tin solder mix merely deforms, reducing stress and
hence minimising whiskering

Whiskers can grow indefinitely

Source: Howard Johnson, Signal Consulting

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
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Re: Lead free solder - exposed in a UK national newspaper


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Isn't it funny how figures can be 'distorted' to make facts suit the
context. By saying "80m kilos", the EPA make it sound like a HUGE amount,
but put that into a more 'recognisable' form, and it becomes 80 thousand
tonnes, which is not nearly so contentious. Then further, take that only 37%
of that was actually lead, and you are down to 29.6 thousand tonnes. Now
compare that to the world's lead-acid battery usage, where recycling of the
end-of-life product to recover the lead, has been sucessfully in place for
years. At 30th tonnes, the potential environmental impact of the lead in
solder, even if you *did* dump it all in the ground, is minuscule.

As I've said before, I'm glad that the avionics industry refuse to use the
stuff. The day they do is the day I stop flying ...

Arfa



Re: Lead free solder - exposed in a UK national newspaper

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And, where do these pin-heads think the lead came from, in the first place?

Jonesy

Re: Lead free solder - exposed in a UK national newspaper
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It came from deep within the ground, in the form of lead ore,
which I think is much less of a health hazard than metallic lead
decomposing in a landfill and seeping into the water supply.

In Europe, there are places where the Romans smelted lead 2000
years ago, and 8" or so below the topsoil, the dirt is still so
toxic that health officials (in Britain at least) don't allow
people to dig there, even wearing protective gear.

BTW, I'm not a pinhead, just someone who cares about my health,
that of others and a quality environment for us to all live in.

I tried lead-free solder, and gave up on it, at least for prototyping.
I was feeling a little bad about returning to traditional solder,
until the OP posted the article. Thanks - I feel vindicated. I hope
that someday there is a better alternative to lead-based solder,
but evidently it hasn't happened yet.

Jay Ts
--
To contact me, use this web page:
http://www.jayts.com/contact.php

Re: Lead free solder - exposed in a UK national newspaper

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Welcome to California.
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I've used 'alternative' solder.  I could live with it if need be.  It
handles differently but geez, I think the fumes would kill me faster
than eating a pound of lead solder everyday at tea.  I've never heard
the proponents addressing the wicked fumes of the 'better' solder.

-Bill (63/37)

--

Re: Lead free solder - exposed in a UK national newspaper
 <snip>
 > I've used 'alternative' solder. A0%I could live with it if need be.
A0%It
 > handles differently but geez, I think the fumes would kill me
faster
 > than eating a pound of lead solder everyday at tea. A0%I've never
heard
 > the proponents addressing the wicked fumes of the 'better' solder.
 >
 > -Bill (63/37)
 >

You mean the fumes from the flux. You don't believe you're breathing
solder vapors, do you? In the 40+ years I've been using solder, I
doubt I've used 5 lbs and I do quite a bit of soldering.

GG

Re: Lead free solder - exposed in a UK national newspaper

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I've never turned on my shop spectrometer to determine if it was the
flux or solder.  I just know that the new stuff doesn't smell as
friendly to my human nose.


40+ years, 5 pounds, yadda,yadda...how much 'new' solder have you used?
  I suspect you're just trying to pick a fight.  I'm not playing.  See ya.

-ex

--

Re: Lead free solder - exposed in a UK national newspaper

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I don't think that he's trying to pick a fight at all ... Depending on
whether or not he's talking 'professional' use, that might be a bit of an
underestimate, but not huge. I hand solder just about every day of my
working life. I use predominantly 0.7mm solder wire, which I buy in 500g
reels. I reckon that each reel lasts me probably 3 years, so in 35 years of
professional use, I have used perhaps 6kg or 13 pounds.

The reason that lead-free solder does not smell as nice, is that it is no
longer a basic natural rosin flux that is contained within the solder.
Because of the new stuff's vastly inferior wetting qualities with most
metals used in electronics, it has to contain a far more aggressive flux to
stand any chance of forming a metallic bond. That aggressive-ness is
achieved by making the flux slightly acidic, so the fumes, if you are
breathing them, are actually gently rotting the linings of your nose and
lungs. There was always a declared H & S issue about industrial asthma with
rosin flux fumes in quantity, but I suspect that this stuff is potentially a
far greater health hazard than rosin fumes ever were. So, if you're having
to use a lot of lead-free in your day to day work, I would suggest that now
is the time to install some fume management, even if it is just an old
computer fan blowing the smoke across to someone else ... :-)

Arfa



Re: Lead free solder - exposed in a UK national newspaper

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    Don't bother trying to educate 'Exray'.  He knows everything about
everything and listens to no one.   Hundreds of companies run annual
tests for lead in the blood, and rarely ever turn up anything.  Those
that do are usually traced to other sources.  Some employees at
Microdyne soldered every day, all day for over 20 years and still came
up clean every year. No one there had ever failed the lead tests.


--
aioe.org is home to cowards and terrorists

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Re: Lead free solder - exposed in a UK national newspaper
 >
 > > You mean the fumes from the flux. You don't believe you're
breathing
 > > solder vapors, do you? In the 40+ years I've been using solder, I
 > > doubt I've used 5 lbs and I do quite a bit of soldering.
 >
 > > GG
 >
 > I've never turned on my shop spectrometer to determine if it was
the
 > flux or solder. A0%I just know that the new stuff doesn't smell as
 > friendly to my human nose.
 >
 > 40+ years, 5 pounds, yadda,yadda...how much 'new' solder have you
used?
 > A0% I suspect you're just trying to pick a fight. A0%I'm not playing.
A0%See ya.

Heavens no. I don't fight. I just try to state facts to the best of my
knowledge with as little embellishment as I can. I don't know about
your soldering tools but we now use only Metcal soldering stations at
work besides my personal one at home. Point is a Metcal has a very
well defined temperature not likely to vaporize solder - though what
tool would?

Tried a very small amount of lead free solder, didn't like how it
behaved and then set it aside to keep using leaded solder until I
can't get it anymore. The antique stuff I work on has leaded solder so
it seems proper to repair it with the same type solder

Oddly, using lead free solder on copper pipe was kind of fun in that
the solder had a very well defined melt point that seemed to almost
instantly flow. IIRC it was 95% tin, 5% antimony.

GG

Re: Lead free solder - exposed in a UK national newspaper

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Indeed, some experts recommend this, saying that mixing leaded and lead-free
in the same joint, reduces the potential integrity of that joint

Arfa



Re: Lead free solder - exposed in a UK national newspaper



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Absolutely. When repairing old kit use leaded solder.

Graham


Re: Lead free solder - exposed in a UK national newspaper
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   I would not know about integtrity, but the MP of the mix is a *lot*
lower than lead-free (solder).

Re: Lead free solder - exposed in a UK national newspaper

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  Invalid link.

  Long before "flux chars" (and no, not all fluxes would be the same),
it would liquefy (change phase) and volatize (evaporate in our
atmosphere).

  Other fluxes would behave differently as well.

 The vapor pressure of a vat of lead at 500 C would certainly have a
specific vapor pressure.

  Are you sure that the Lead / Tin alloy that solder is would have the
same vapor pressure?

  Also, there are no irons for the electronics industry I am aware of
that operate at 932F.

Re: Lead free solder - exposed in a UK national newspaper
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Ditto. I have half a pound right here that I bought at a hamfest in the
eighties. Used it to put together a Wersi Delta years back, used it for
other kits and copious repairs. Even waste a ridiculous amount tinning
my soldering tips (the current one is from the seventies and helped with
the Delta).

--
           http://apnews.myway.com/article/20080331/D8VOMVT02.html
                   Chelsea Clinton Criticizes Bush in N.C.

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Re: Lead free solder - exposed in a UK national newspaper

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Basically, there isn't a lead-free alternative that works the same, or even
close, but you're missing the point(s). Firstly, there isn't *quite* such a
huge amount or disposal problem as they would have you believe. Second, the
lead in solder is pretty firmly 'locked into' the alloy, such that it
doesn't readily come out of the solder into water. Yes, I know that acid
rain can have some effect on that equation, but that's nothing like as bad
as it once was. Finally, all electronic equipment in Europe at least, is now
subject to the WEEE directive, which dictates the way it is treated at end
of life, covering recycling and disposal of the remains that can't be
recycled. There is no reason at all that leaded solder could not be
recovered and recycled, in the same way as lead free solder. 80% of the
world's metallic lead production goes to automotive battery manufacture.
Lead recovery and reuse from that product at end of life, has been mandated
and successfully carried out, for years.

I think that this is the reason that most people who have to use lead-free,
get so wound up about it. As far as I am concerned, the legislation that
mandates its use, is ill-considered, not thought through, unnnecessary in
the light of the legitimate WEEE directive, and effectively replaces a
mature and reliable technology, with one that has the potential to be
directly dangerous to human life, if it ever finds its way into avionics,
medical, and military applications, which so far, have managed to secure
exemptions.

Like any sensible person, I don't want to deliberately pollute the planet
for those who come after me, but in recent years, many badly informed
decicisions on this sort of thing, have been made by departments 'jumping on
the banwagon' to justify their own existence. The whole thing isn't helped
by celebrities and ex famous politicians serving their own public eye needs
through 'green' issues. It has actually reached the point where I am now
sick to death of hearing the words "green" and "eco" and "carbon footprint"
and "geenhouse gas" and "cimate change" and "global warming" every single
time I turn on the radio or TV. So here's a new word.

Ecobollocks. Covers what a lot of this bull actually is ...

Arfa



Re: Lead free solder - exposed in a UK national newspaper
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Instead of banning polluting substances, we should be regulating the
pollution they create.

In other words, it doesn't matter how much of a harmful substance you use in
manufacturing a product, but how much of it gets into the environment. It's
the latter we should be worried about, not the former.



Re: Lead free solder - exposed in a UK national newspaper
snipped-for-privacy@comcast.net says...
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I think you have hit on something here.


Re: Lead free solder - exposed in a UK national newspaper

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Sentiment seconded.

Message sorted headers by date from my nntp provider:

Re: Lead free solder - exposed in a UK national newspaper     Arfa Daily
Lead Generation Computer Systems                              liukaiyuan
...

I expected to see an advert for cpus soldered with 63/36 or 60/40 ;)

Michael

Re: Lead free solder - exposed in a UK national newspaper
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   Try tin/silver, *no* copper.
   Nice shiny (sexy looking?) surfaces, easy to solder, have seen no
problems in 2 years where circuits get a lot of temperature cycling.

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