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Lead free solder - exposed in a UK national newspaper

N

N_Cook

Jan 1, 1970
0
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
 
A

Arfa Daily

Jan 1, 1970
0
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.


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
 
T

TheM

Jan 1, 1970
0
Eeyore said:
About time too.

Never mind the reduced reliability (see the ERA study) caused by lead-free
solder when equipment is exposed to vibration.

Graham

Its good for the way economy works nowadays. Buy, buy, buy the crap
that dies or obsoletes every 2-3 years.

Mark
 
N

N_Cook

Jan 1, 1970
0
Eeyore said:
About time too.

Never mind the reduced reliability (see the ERA study) caused by lead-free
solder when equipment is exposed to vibration.

Graham

Before I waste time downloading an irrelevant pdf

would this be what you be referring to :

Review of Directive 2002/95/EC (RoHS) Categories 8 and 9 - Final

http://ec.europa.eu/environment/waste/pdf/era_study_final_report.pdf

Results of vibration testing lead-free solder from different researchers ...
 
A

Allodoxaphobia

Jan 1, 1970
0
At 30th tonnes, the potential environmental impact of the lead in
solder, even if you *did* dump it all in the ground, is minuscule.

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

Jonesy
 
J

James Sweet

Jan 1, 1970
0
William Sommerwerck said:
As I've said before... It isn't a matter of whether electronic equipment
has
lead in it, but what happens to that equipment when it's disposed of. It's
the latter that should be considered.


And lead isn't the only toxic substance used in electronic equipment and the
process used to manufacture it.

Is a lead-free item that fails and ends up in the landfill after 2 years
better than a lead-containing device that lasts a decade?
 
E

exray

Jan 1, 1970
0
Jay said:
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.

Welcome to California.
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.

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)
 
Jay Ts wrote:
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)

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
 
E

Eeyore

Jan 1, 1970
0
William said:
As I've said before... It isn't a matter of whether electronic equipment has
lead in it, but what happens to that equipment when it's disposed of. It's
the latter that should be considered.

AIUI, lead in metallic form is pretty stable and doesn't 'leach' into
groundwater the way some would have us believe.

Graham
 
E

exray

Jan 1, 1970
0
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. 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
 
P

Phil Allison

Jan 1, 1970
0
"Jay Tossers"
Another source of lead is CRTs, many of which are still in use.
They contain about 5 pounds of lead each for radiation protection,
quite a bit more than is contained in the solder in the PC boards.



** Silly comparison.

Glass does not break down in the environment.

So how would any of that lead get out ??



....... Phil
 
N

N_Cook

Jan 1, 1970
0
Eeyore said:
....

Not sure if that's the one I had to be honest but looks interesting.

Graham

One small bit from that study

"Solder joint failure due to vibration becomes more significant as the
frequency of vibration approaches the resonant frequency of the component or
structure.
Studies by Chuang et al 29 and
Song et al 30 have sought to identify microstructural features that
influence the performance of conventional Sn-Pb solders and candidate
replacement lead-fre solders. The typical microstructure of conventional
Sn-Pb solders containing coarse pro-eutectic grains reduces the ability of
these materials to absorb energy during crack formation and hence reduces
the vibration resistance of joints made using these solders. "

I thoutht distributed irregularities in structures, suppressed crack
propogation.
Would seem NOT to be borne out for the case for premature failures of solder
joints for unsupported dropper resistors in mucic combos - ie amplifiers
contained within the same case as large speaker/s.
Failure in 2 or 3 years of routine use wheras more like 20 years for failure
in similar but older PbSn manufacture.
 
A

Arfa Daily

Jan 1, 1970
0
Jay Ts said:
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

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
 
A

Arfa Daily

Jan 1, 1970
0
exray said:
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

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
 
A

Arfa Daily

Jan 1, 1970
0
James Sweet said:
And lead isn't the only toxic substance used in electronic equipment and
the process used to manufacture it.

Is a lead-free item that fails and ends up in the landfill after 2 years
better than a lead-containing device that lasts a decade?
And is then properly recycled ?

Arfa
 
A

Arfa Daily

Jan 1, 1970
0
Phil Allison said:
"Jay Tossers"




** Silly comparison.

Glass does not break down in the environment.

So how would any of that lead get out ??



...... Phil
Apparently, in America, they crushed the glass to powder or some such to try
to prove this. I'm sure that someone from that side of the pond, knows the
details. The lead which is contained in the faceplate glass to minimise x
radiation to acceptable levels, is actually not metallic lead, but lead
oxide, and is very firmly locked into the molecular structure of the glass,
so wouldn't readily leach anyway. 5 pounds of lead is probably a bit on the
enthusiastic side on average. 'Big' tubes may contain this amount, or even a
little more, but average sized ones, and computer monitors, would probably
be around half or a little more, than that figure. LCD displays, of course,
do not require this radiation protection.

Arfa
 
J

James Beck

Jan 1, 1970
0
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.
Mettalic lead has been shown to have very little impact on the
environment. Especially after it has built up an oxide layer.
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.
Ah, but we aren't talking about running a smelting operation, are we?
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 don't know.
Comparing burying metallic lead VS a smelting operation, that borders on
pinheadiness.
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

Until they come up with better alternatives, I'll stick with good old
lead/tin. When I left my last job, I had a full physical including a
lead test, and even though I had been "exposed" to lead solder almost
daily for 13 years, my blood lead levels were almost not measurable and
that puts me below the national average for people that don't work with
solder at all. Why would that be if lead/tin solder were so dangerous?

Jim
 

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