Tin Whiskers

[T3sl4co1l]

I'm not sure what Germany's history of lead use is like (depending on how far back you go, as well), so you may well have a different perspective than the situation in the US, or other places.

Lead exposure (principally via paint -- babies put their mouths on literally *everything* -- and via soil, and things growing out of that soil) has been correlated pretty strongly with increased aggression and poverty.  The correlation is spacial (i.e., between areas with and without such conditions) and temporal (they were worse when lead was used regularly, and have dropped considerably since lead was banned in the sources -- paint pigments and gasoline).

In most areas, water is a very low risk indeed, even considering some water mains are original lead pipe.  The reason is, calcium, carbonate and sulfate ions in the hard water in these locations keep the lead insoluble, where it remains as a corrosion resistant surface inside (and outside) the pipe.  In areas with different water chemistry (more organics, acidity or salinity, I think?), lead can be dissolved in the water, and the water mains must be investigated and replaced.

There's no such thing as "acute lead poisoning" -- well, I'm sure there IS, but it's not the problem.  The problem is *chronic*, and the problem is worst when the bones are growing rapidly (where serum lead co-precipitates with calcium, with a half life of years to decades), which are also the most formative years for the brain.  Biological absorption via ingestion (includes inhalation, by swallowing sputum) ranges from ~10% in adults to 50-90% in children growing rapidly.

Lead is not a potent carcinogen, and no one will spontaneously grow a third arm (or be at greater risk of bearing children with additional appendages) as a result of its exposure.

The hazard is real, and joking it away flippantly is not only hurtful to its victims, but insensitive to those who actually suffer from deformities as a result of other chemical exposures.

Tim

[helius]

Referring to iatrogenic poisoning incidents as "chemical exposures" is beyond bizarre.

[LabSpokane]

The issue with water contamination not being a major problem is misleading. Downstream of our superfund site, while *dissolved* lead concentrations in water are not a huge concern, the water will transport a red froth that consists mainly of iron which combines with lead, mercury and cadmium. That froth coats the banks of the river downstream, creating a toxic scum for animals and the unwary.

[T3sl4co1l]

The issue with water contamination not being a major problem is misleading. Downstream of our superfund site, while *dissolved* lead concentrations in water are not a huge concern, the water will transport a red froth that consists mainly of iron which combines with lead, mercury and cadmium. That froth coats the banks of the river downstream, creating a toxic scum for animals and the unwary.

I was speaking of established drinking water systems; around superfund sites, mine tailings, and so on, the runoff can get quite nasty, as you say, both from dissolved or suspended contents!

Tim

[LabSpokane]

The issue with water contamination not being a major problem is misleading. Downstream of our superfund site, while *dissolved* lead concentrations in water are not a huge concern, the water will transport a red froth that consists mainly of iron which combines with lead, mercury and cadmium. That froth coats the banks of the river downstream, creating a toxic scum for animals and the unwary.

I was speaking of established drinking water systems; around superfund sites, mine tailings, and so on, the runoff can get quite nasty, as you say, both from dissolved or suspended contents!

Tim

Tim,

I agree with what you said. I'm actually referring to Peter's comments prior to yours. Sorry for not quoting.  We are on the same page. It is just nothing to laugh off anymore. The evidence of the consequences of chronic metals exposure is so well documented and observable by the layperson, that there is no point in further debate upon the matter.

The debate over the merits of RoHS is a different animal. I would choose to add a little lead back in, and simultaneously push for the right to repair and recycling. The reality is that mining, not disposal is the real source of most contamination.

[VK5RC]

Re lead and soldering,  there is a real study of frequent solderers in qex which showed NO increase in blood lead of those who use lead solder.  Other fumes worry me more,  flux not much,  some of the plasticisers are more worrying.  Fresh moving air is pretty good!

[Whales]

Re lead and soldering,  there is a real study of frequent solderers in qex which showed NO increase in blood lead of those who use lead solder.  Other fumes worry me more,  flux not much,  some of the plasticisers are more worrying.  Fresh moving air is pretty good!

I've read a few people say that leaded solder alloys somehow don't dissolve well in humans, but I don't know of any evidence to back it up.  I'm heavily sceptical -- can anyone find a (publicly available) study/findings/etc ? 

[VK5RC]

If you 'eat'  leaded solder long term you will get in trouble I am pretty sure,  hand washing works very well. The lead in solder I don't think is in an amalgam like the mercury in teeth filling amalgam. So I think the lead in leaded solder is bio-available,  poor absorption but even poorer elimination ie accumulation.
I have treated a young man with acute cns lead toxicity from sniffing leaded petrol (many years ago).  I don't know the composition of the 'lead' in petrol but it must be volatile enough to get inhaled into both engines and blood!

[G7PSK]

Tin is not exactly good for you if ingested in any way.  http://en.wikipedia.org/wiki/Tin_poisoning.
The stupidest thing I have heard from the anti lead brigade is the removal of all lead from the bullets fired by the British army, as if having been hit by such a projectile you would be concerned by the lead content.

[PeterFW]

Lead is not a potent carcinogen, and no one will spontaneously grow a third arm (or be at greater risk of bearing children with additional appendages) as a result of its exposure.

I know, i know... and i know the differences and effect of long time lead exposure.
That stuff is very bad for your, yes.

We should remember, all the fuss about lead was caused by problems on a industrial scale before we knew and cared about what the real dangers of long time exposure are.
We threw that stuff at and in everything, in walls, on roofs, in paint, water lines, industrial waste dumped in the ocean...
That was bad, very bad indeed.

And that was not what my comment was about.
I was speaking about fishermen, hunters, sculpters, historic building maintenence, home soldering... everything were we use lead on a small scale basis, in "big chunks".

There, the occasional lead exposure is no problem as long as you do not eat it, put your head over the smelting pot and take deep breaths and wash your hands afterwards.
Yes, "no problem" is of course the wrong phrase.
But today everything has been proven to be bad for you or give you cancer.
As long as you use some common sense, you will be good.

[free_electron]

Tin whiskers are only a small problem. Read up on CAF ( cathodic-anodic filament ) in circuit boards ... or dendrite formation on the surface due to insufficient flux removal. a drop of water can produce a hard metallic dendrite in like 12 seconds flat ...

same goes for conformal coating. let's slap it on ... without sufficiently decontaminated surface : a nightmare waiting to happen . i just had a 2 day training on that stuff.. hair raising what kind of defects occur.

[T3sl4co1l]

Had a second-hand customer where they were having failures.

The circuit was poorly drawn to begin with.  I don't know what they were thinking when they "designed" and reviewed this.  But alas, that was years ago, many engineers past, and a corporate restructuring (of my client, not the end customer).

Looking at the claimed failure mode, I was stumped.  There should be no way that can happen, even given that the circuit is nonsense.  (On a related note: an op-amp will read somewhere between 0V and VCC at its output, when its inputs are shorted together.  How much (input offset) varies with board flex!)

Talking with another engineer who's more involved with the customer, I learn they don't wash their boards.  Hoo boy.  Oh, and they use conductive flux, so if there's anything nearby at all, basically every node in the circuit is about 100kohms apart, maximum.

Oh, and the customer also wants this to pass environmental.  It's not passing (surprised?), so they're just going to glop conformal on it and call it a day.

  !!

It gets better...  said customer has their production in-house.  Which sounds like a good thing, right?  Ah, but you see... they don't want to add a wash step, because it's extra time "wasted".  And they don't want to change fluxes or processes, because... who the fuck knows.

(There's not been one conversation about this customer where I've gotten a sense that they have a freaking clue what they're doing.  It's just bizarre that such a mess can survive.  And for years, at that!)

Tim

[Rick Law]

In short, lead is toxic. The main problem isn't immediate death. The problem is that continued exposure causes long term health and mental developmental problems - particularly in children.

For anyone who doubts the human health effects of chronic lead exposure, you are hereby cordially invited to our nearby Superfund Cleanup site at Kellogg, Idaho, USA. In the 1980's, the children tested there has the highest blood concentrations of lead in the world. Many of those exposed are still there today. Come see the results and feel free to arrive at your own conclusions.

We also have a bonus side trip! We'll go for a bike ride down the valley from the cleanup site where you can see acre after acre of dead swans - who die from eating the lead-laden mud that covers the tubers that are a food source.

---------

Please do not interpret the above as an endorsement of RoHS.

Kellogg site is a mining site.  How something is mined is independent of how that something is used.  One can mine very clean stuff in a very dirty way.

There is no disagreement that lead is toxic link many other heavy metal.  The issue really is how lead in solder affects users and how disposal of used-electronics affects residents near disposal sites.  In this discussion, user is the solderer but not the end-user of the electronics.

I don't mind reasonable approach to ensure environmentally friendliness.  I do object to single minded absolutist approach.    Absolutist often come up with approach with far costly down-stream impact than the original pollutant.

Beyond environment impact, we also have to be concerned about financial impact.  Would a clean environment do more for the people verses having heated homes in the winter freeze?  Cost increase reduces living standard, that is simple arithmetic.  Dirty environment reduces life expectancy, that is common sense.  So one must seek a reasonable balance.  Absolutist fails to see the negative so simply ignore the negative.  That is what I object to.  I agree with their goal, I just object to their purest approach.

Risk exists all around us.  We just need to be reasonable about it.

[LabSpokane]

In short, lead is toxic. The main problem isn't immediate death. The problem is that continued exposure causes long term health and mental developmental problems - particularly in children.

For anyone who doubts the human health effects of chronic lead exposure, you are hereby cordially invited to our nearby Superfund Cleanup site at Kellogg, Idaho, USA. In the 1980's, the children tested there has the highest blood concentrations of lead in the world. Many of those exposed are still there today. Come see the results and feel free to arrive at your own conclusions.

We also have a bonus side trip! We'll go for a bike ride down the valley from the cleanup site where you can see acre after acre of dead swans - who die from eating the lead-laden mud that covers the tubers that are a food source.

---------

Please do not interpret the above as an endorsement of RoHS.

Kellogg site is a mining site.  How something is mined is independent of how that something is used.  One can mine very clean stuff in a very dirty way.

There is no disagreement that lead is toxic link many other heavy metal.  The issue really is how lead in solder affects users and how disposal of used-electronics affects residents near disposal sites.  In this discussion, user is the solderer but not the end-user of the electronics.

I don't mind reasonable approach to ensure environmentally friendliness.  I do object to single minded absolutist approach.    Absolutist often come up with approach with far costly down-stream impact than the original pollutant.

Beyond environment impact, we also have to be concerned about financial impact.  Would a clean environment do more for the people verses having heated homes in the winter freeze?  Cost increase reduces living standard, that is simple arithmetic.  Dirty environment reduces life expectancy, that is common sense.  So one must seek a reasonable balance.  Absolutist fails to see the negative so simply ignore the negative.  That is what I object to.  I agree with their goal, I just object to their purest approach.

Risk exists all around us.  We just need to be reasonable about it.

I'm arguing for reasonableness as well. I brought up the example because the toxicity of environmental lead was questioned. To flippantly dismiss metals toxicity as has been mentioned is not reasonable. Nor is the opposite extreme of shutting down civilization.  So, we use common sense and good science to make good compromises to protect human and environmental health.

 I solder with lead. I also respect its toxicity.

[Rick Law]

In short, lead is toxic. The main problem isn't immediate death. The problem is that continued exposure causes long term health and mental developmental problems - particularly in children.
...
Please do not interpret the above as an endorsement of RoHS.

Kellogg site is a mining site.  How something is mined is independent of how that something is used.  One can mine very clean stuff in a very dirty way.

There is no disagreement that lead is toxic link many other heavy metal.
...
Risk exists all around us.  We just need to be reasonable about it.

I'm arguing for reasonableness as well. I brought up the example because the toxicity of environmental lead was questioned. To flippantly dismiss metals toxicity as has been mentioned is not reasonable. Nor is the opposite extreme of shutting down civilization.  So, we use common sense and good science to make good compromises to protect human and environmental health.

 I solder with lead. I also respect its toxicity.

Actually, your "arguing for reasonableness" came through well.  I was quoting you in agreement.

I point out that site being a mining site to "pre-emp" (as in preemptive) it from being use as "see what you leaded solder cost..."

[LabSpokane]

Gotcha Rick. Yup, that would be a logical fallacy best left unsyllogized.

[Stonent]

Spoilers: "cromulent" and "embiggening" are from The Simpsons.

A noble heart embiggens the smallest man.

Interestingly "embiggens" was in my phones dictionary and I didn't have to override the autocorrect.

[Rick Law]

Spoilers: "cromulent" and "embiggening" are from The Simpsons.

A noble heart embiggens the smallest man.

Interestingly "embiggens" was in my phones dictionary and I didn't have to override the autocorrect.

Ha, you guys are still on "cromulent" and "embiggening".  I had to look up the dictionary to find out what that two words mean.

Usually, when I made up a word, my excuse is English is not my first language.  But this time, it was plain carelessness on my part.  Such carelessness is some what "upsadding"...

[Bassman59]

Spoilers: "cromulent" and "embiggening" are from The Simpsons.

I, for one, welcome our new linguistic overlords.

[Red Squirrel]

That was interesting, I never knew about this phenomenon.  Could it be the cause of random failures in stuff like computer equipment?  Tin whiskers on the motherboard, or cpu etc?   Though given their size I would have thought they'd just short and burn and the circuit would continue to operate.  I guess if it happens on a logic level circuit then it wont have enough power going through it to burn.

I think I might remember that satellite incident too... I just remember one time as a kid, the TV and lot of stuff was not working and it was to do with satellites, though I remember it being more drastic and involving multiple satellites so not sure if it's another incident I'm thinking of.

[helius]

The US Environmental Protection Agency evaluated 63/37 against several lead-free solders in a total life-cycle assessment of environmental and health effects. They found that leaded solder presents a greater risk to personnel who handle the material, due to the toxic effects of lead. However, the lead-free SAC solder was found to be most damaging to the environment and public health in 10 out of 16 categories including global warming, ozone depletion, acid rain, and public health-cancer.

http://www2.epa.gov/sites/production/files/2013-12/documents/lead_free_solder_lca_summary.pdf

[CatalinaWOW]

Tin whiskers are real, and have caused real failures.  Not often.  Even when they occur they mostly just blow clear with only momentary effects.  They matter when you are doing medical, industrial or military equipment where any failure may cause loss of life.  Not so much of a problem for consumer and hobby and even automotive electronics where poor reliability is accepted. 

Lead toxicity is real, but the dangers are wildly overblown.  When a shooting club I belonged to was shut down there was a movement to do a full hazardous waste treatment on the range, which was in a national forest recreation area.  Those pushing expressed concern that hikers and animals would be endangered merely by walking through the area.  As a defense against the expense, two employees of the club, who had walked and worked on the range six days a week for more than twenty five years were tested.  These same two persons also were ammunition reloaders who frequently cast bullets and handled huge quantities of lead shot.  They also were game hunters who fairly regularly ate birds which had been shot with lead shot.  The results; their blood levels of lead were not only below acceptable limits, but below detectable limits.

It takes real effort to get lead poisoning.  You have to eat and chew on lead based paint, or have lived next to a major superhighway with high traffic before lead was eliminated from gasoline, or eat acidic foods of and out of certain lead containing pottery daily for a long time, or something similar.  The Romans used lead very widely and unwisely and it still took centuries for the effects to catch up with them.

[SeanB]

Main cause for the Roman lead poisoning was the method they used to make sweet wine, which involved storing the wine in lead lined vats, which dissolved into the wine creating a sweet tasting lead salt.

http://en.wikipedia.org/wiki/Ancient_Rome_and_wine

http://en.wikipedia.org/wiki/Lead%28II%29_acetate

[CatalinaWOW]

Yep.  Sweet wine.  Lead glazes on pottery with a nice acid fish sauce.  And all of the plumbing was lead.  Not to mention lead and pewter dining ware.  Still wasn't very effective in killing them off.  Took the help of barbarians to the north and a few other problems.

[T3sl4co1l]

And like I said, there are lead water mains still in use in the "civilized" world today -- as long as the corrosion stays in place, insoluble and protective, who's the wiser -- and who cares?

Tim