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Tin Whiskers — Fact Or Fiction?
bLanark writes "Some time ago, most electronics were soldered with old-fashioned lead solder, which has been tried and tested for decades. In 2006, the EU banned lead in solder, and so most manufacturers switched to a lead-free solder. Most made the switch in advance, I guess due to shelf-life of products and ironing out problems working with the new material. Lead is added to solder as it melts at low temperature, but also, it prevents the solder from growing 'whiskers' — crystalline limbs of metal. The effect of whiskers on soldered equipment would include random short-circuits and strange RF-effects. Whiskers can grow fairly quickly and become quite long. Robert Cringley wrote this up this some time ago, but it seems that the world has not been taking notice. I guess cars (probably around 30 processors in a modern car) and almost every appliance would be liable to fail sooner than expected due to tin whiskers. Note that accelerated life-expectancy tests can't simulate the passing of time for whiskers to grow. I've googled, and there is plenty of research into the effects of tin whiskers. I should point out that the Wikipedia page linked to above states that tin whisker problems 'are negligible in modern alloys,' but can we trust Wikipedia? So: was the tin whisker problem overhyped, was it an initial problem that has been solved in the few years since lead-free solder came into use, or is it affecting anyone already?"
grow whiskers. That would be a major bummer. But then lead would be pretty heavy.
My cat gets through tins of Whiskas extremely rapidly. Perhaps scientists can interview him.
SnAgCu Rohs solder(with 3% silver and .05% copper) joints don't appear to whisker but they appear dimpled and shitty compared to the smooth, shiny joints of garden-variety tin/lead. At least in the electronics industry, your percenteges and mileage may vary.
One thing to remember is that safety control and monitoring products like fire alarms, but probably also car electronics, are excepted from the RoHS directive until at least 2012, possibly until 2018, but there's really no fixed date set yet. So yes, your DVD player might die, your car probably won't.
c++;
Cars, televisions, players, music, computers... are there really any electronics intended to last 30 years any more?
Oh, you're not stuck, you're just unable to let go of the onion rings.
Imagine a ...er, no..
I blame Mic..hang on..
The RIA...Uh..
In Soviet Ru...Damn..
SCO probably...fu..
Does solder run Lin...um...
Bah!
AT&ROFLMAO
Well, NASA Goddard are worried about the situation and they have done extensive studies on the subject:
http://nepp.nasa.gov/WHISKER/
Ganty
Tin whiskers are, in fact a reality. They are a problem with pure tin specifically. The older tin-lead, and newer tin-vanadium alloys don't have the problem. However, many manufacturers still manufacture parts in a pure tin variety. The reason for all of this pure tin madness is that the EU passed strict anti-lead regulations and so the lead had to be removed from electronics. EU manufacturers immediately started using pure tin parts. In the US, many manufacturers followed suit, partly because pure tin parts were now more available than tin-lead (and at the time there was hardly any tin-vanadium), and partly because they wanted to maintain a good environmental image. Some manufacturers, having been burned by the whisker problem insisted on a better solution hence the tin-vanadium solders now available. The problem is there are a lot of electronics out there with pure tin parts in there. For example, I'm no fan of flying on Airbus aircraft manufactured in the late '90s and early 2000s (pure tin baby). The thing is, the hardware will work perfectly... until it doesn't, then an errant short will cause a malfunction and in the act, the tin whisker will vaporize. The only way you'll find the problem is with electron microscopy.
Any whiskering is far more likely to be a result of board contaminants than just the tin migrating. Modern solders are less forgiving of bad handling practices.Poor flux choice and board cleaning practices are normally to blame for many faults. Changes in board cleaning practices to eliminate various chemicals means that the industry has had to learn how to do things again.
So, while modern practices might be less forgiving, any faults are really just a result of poor processes.
Engineering is the art of compromise.
Look at it from the manufacturer's point of view. There's a chance that any piece of consumer electronics is now going to wear out and die even faster, causing people to buy replacements more frequently. Sounds like a great deal for the manufacturer with no downside. They don't have to pay to dispose of these things properly. And no, chucking your old electronics in the trash is not the proper way of disposing of them, unless you like cadmium, mercury, hexavalent chromium, and brominated flame retardants seeping into your drinking water.
Make manufacturers bear the ENTIRE cost of properly and safely disposing of their products, and overnight we'd have cleaner, greener, more long-lasting and durable products.
Tin Whiskers appear real:
http://nepp.nasa.gov/WHISKER/background/index.htm
http://www.calce.umd.edu/lead-free/tin-whiskers/
From what I can tell from these links there issue is still present in lead-free solder, and very much an issue in certain conditions. I have not seen any pages which indicate long-term solutions, though it would be interesting if someone can turn one up.
Another link:
http://www.national.com/analog/packaging/leadfree
Jumpstart the tartan drive.
I used to buy into Wikipedia's stated ethos until I realized that any one person can (and all too frequently do) hijack articles to push and protect their point of view and once that happens you can forget about the "Five Pillars" and objectivity.
Years ago I used to work on GE radio equipment. GE radios (Master II series) had tin-plated resonant cavities in their receivers. Tin whiskers were seldom a problem in the mobile radios as vehicle vibration tended to keep the whiskers knocked off. But in base stations the whiskers would grow along the lines of current until they shorted out the coils within the cavities.
The symptoms were always the same. The radio would be working fine one minute and be stone-deaf the next. Sometimes just opening the cabinet door would be enough to dislodge the whiskers and remove the short. But it always returned a few days or weeks later. We got to the point where whenever we were sent out to fix a deaf base, our first repair technique was to take a large screwdriver and rap the cavities with the handle a couple of times, hard. We got some funny looks from the customers but they were happy to be back on the air.
GE finally admitted that the plating was the problem and shipped us a bunch of cavities with a different alloy to use as replacements. They never would tell us what the difference was. Curious, we disassembled some of the old cavities and shook out tiny metal slivers that were finer than a human hair. Some were up to a centimeter in length.
All of the radios we had problems with were less than five years old at the time.
On a somewhat unrelated note, a friend of mine works for a company building avionics. They're still using Lead/Tin/Silver solder for US military contracts. He thinks they know something the rest of us don't.
Beta sux! Join the Slashcott! http://hardware.slashdot.org/comments.pl?sid=4760465&cid=46173047
"Goodness me, how unlike the FBI to abuse the trust of the American public." -- The Onion
I understand the rationale for getting rid of lead in various products due to its toxicity, but is the amount of lead in solder really dangerous ? It seems like it would be such a small quantity, and perhaps more importantly it's sealed away in some plastic or steel enclosure... it's not like I go around licking motherboards all day long, and quite frankly if your kid wants to lick lead solder and you let him, brain damage might be an improvement!
-Billco, Fnarg.com
Did he have tin whiskers?
If you are going to troll, at least be on-topic.
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
Several times editors on both sides of an issue have been banned for edit-warring and aggressively reverting changes they don't agree with. Usually this happens over controversial political and religious articles. This process usually takes months and is preceded by other means, including attempts to resolve the dispute peaceably, administratively-protecting the article, and other mean.
Also, when a philosophical-minority or fringe group tries to take over a highly-watched article, administrators eventually silence them if they insist on using unreliable sources or not keeping the article in "proper balance," where "proper balance" reflects the real-world opinions on the subject. Pseudoscience, alternative-history, and similar-subject proponents tend to get banned if they aren't careful.
Low-traffic articles nobody cares about are very vulnerable to this kind of abuse though.
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
More importantly, where in "the Wikipedia page linked to above" did it state "that tin whisker problems 'are negligible in modern alloys'"?
I saw nothing that said that in current version, and it hasn't been edited (minor or otherwise) since June 13th. I certainly cannot find that single-quoted statement.
I am all for scrutinizing Wiki pages, and not using unverifiable statements from them, but I will not support discrediting them on material that was not written on them in the first place.
You can hold down the "B" button for continuous firing.
Yeah, as long as you're certain the slashdot crowd is dependable, honest and therefore trustworthy...
http://images.pennnet.com/articles/lfe/thm/th_162485.jpg http://www.gaw.ru/im/_publ/ineltek/pb-free/fig4.jpg
I'm sorry but I don't see the danger to life and limb these politicians do in the tiny dimples of lead alloy solder which are enclosed in numerous tough outer casings.
Have there been any studies comparing this "health risk" to your average city's smog layer?
Lead has its place in society. It's not as if lead based solder is being used to paint walls or as inlay in children's toys.
VLC FOR MAC IS DYING! IF YOU DEVELOP, PLEASE SAVE IT!!
Or just follow the links to the original sources that the Wikipedia article cites.
If your computer has a limited life expectancy, then you have to buy a new one at some point. So why would they 'fix' the problem ?
---- Booth was a patriot ----
I've had several equipment fail, not because of tin whiskers, but because of crappy capacitors that leaked and/or burst.
Zinc whiskers are also a problem - specifically if the raised floor in a datacenter is held up by older galvanized steel standards. i've actually got a client with this issue - you can see the whiskers on server motherboards with a flashlight held at an oblique angle.
symptoms included random server failures, power supplies and pdu's exploding (had one go off when i was in the room - NOT FUN)
they not only had the old standards, but the roof overhead was steel, soldered with a solder that also contained zinc.
What's interesting is, nobody seems to draw a parallel between spikes that appear when clear water is frozen and tin whiskers.
Something very similar happens - as the temperature goes down, spikes/whiskers appear. It only happens in pure or near-pure water. And it's a well established fact (although not well understood until recently).
This is too much of a coincidence to not investigate it.
Did you know that "FTW" ("for the win") is a direct translation of "Sieg Heil"?
The problem of tin whiskers is real but the consequences ascribed to them by Cringley are not. A printed circuit board like the one in your computer or TV is made of fiberglass and copper layered in a sandwich. In the early days of electronics the copper was plated with tin to prevent corrosion, but scientists discovered that pure tin tends to form hairlike growths, causing the circuits to fail. Adding lead to the tin prevented the growths, and had other desirable properties, so the tin/lead alloy became a universal standard.
More recently we got something called "the restriction of the use of certain hazardous substances in electrical and electronic equipment" or RoHS. RoHS prohibits the sale of materials containing more than 1% lead in the EU. (Old-style electronic assemblies use 37% lead solder.) RoHS came into force in 2006 but research into lead-free electronics began decades ago. Initially researchers tried pure tin plating, which lead to tin whiskers. Some products marketed in the late 90's even failed from this problem. But researchers did not throw up their hands in despair. RoHS has led to innovations in metallurgy to the extent that a circuit board designer can now choose from half a dozen different alloys. Today only 2% of printed circuit boards use tin plating.
Some of these new alloys use gold or silver finishes over copper. These are completely immune to tin whiskers. The most popular new system eliminated the plating step, attaching components directly to the bare copper using chemicals called Organic Solderability Preservatives. OSP leads to stronger and more durable assemblies than even the old tin/lead process.
The whining we see today on the subject of RoHS mirrors almost perfectly the doomsaying seen when California began regulating automobile emissions. There was at that time a tremendous amount of yelling about how the catalytic converter spelled the end of civilization as we know it, and only a moron would take the lead out of gasoline. But soon afterwards we saw the introduction of clean, efficient, powerful cars by Honda. Honda was even able to meet California emissions standards without using catalytic converters or even fuel injection. Their brand of engineering eventually trickled down to even the most benighted American car maker, and California emissions standards are now in force in every industrialized nation.
I would expect to see the same thing with RoHS. We have only just entered the initial stage of complaining. The tin/lead dinosaurs with backwards-looking engineering departments face an existential crisis. In other design houses the challenge of lead-free assembly is being embraced as a competitive advantage. Those who can adapt to RoHS will thrive and those who cannot will clearly suffer.
Cringley brags about a 1966 Thunderbird with a 428 cu. in. motor, a car so heavy, so polluting, and so slow by modern standards that it would be impounded by CARB and laughed off a drag strip by a base model minivan. As time goes on I think Cringley's views on the metallurgy of printed circuit boards will seem as antique at that T-Bird.
"Probably we don't have any major car manufacturer sued because nobody ever cares to examine cars electronics after accidents. It's so easy to blame the drunk/distract/incompetent driver."
:)
Especially when they ARE drunk/distracted/incompetent.
Automobile systems are very well designed to fail gracefully or just not matter much when they crap out. (That's also why drive-by-wire is a stupid idea.)
The average car is driven by a mechanical illiterate who barely maintains it (washing does not count) and is designed accordingly. I am an experienced mechanic and know whereof I speak.
"This post is an artistic work of fiction and falsehood. Only a fool would take anything posted here as fact."
Does a conformal coating stop the whiskers from growing?
the exemption for military electronics.
RoHS may b e good for plebes, but the ruling class can't risk losing control.
"National Security is the chief cause of national insecurity." - Celine's First Law
The board was in the field in a T&M application for about 1 year. Root cause pointed to 2 factors. First the board had very poor (actually out of spec) via to pad alignment. The result was significantly increased voltage density between the offending 12V via and the ground plane. The second factor WAS RoHS compliant board prep and solder. Basically drilled and plated via holes are not 100% sealed (rough bits of fiberglass can still protude through the plating). The solder was one of these high Tin (97%) varieties, and we got dendrite growth (not the more common whisker growth) INSIDE the board along the fiberglass fibers between the via hole and the ground plane, creating a short from a ~30A power bus to ground. The board caught fire. Indications are that it creates a crappy short that repeatedly fries open, and regrows causing intermittents, then eventually enough heat for fire if the power supply can handle it. Higher power electronics with dendrite growth or tin whiskers may fail only briefly (or not at all) when a wimpy short occurs. Low power signal lines won't always have enough juice to overcome the short and may fully die on the very first short. Our safety/reliability group said dendrite growth is a known, but poorly talked about issue that is greatly exacerbated by the lack of lead, and greatly increased board densities today. To a previous post about melting points. Yes, Tin/Lead solder melts well below the melting point of either element in the alloy, at about 175-180C depending on the particulars. NASA literature indicates that conformal coating is ineffective against whisker growth. At a previous defense sub-component job we had to resort to getting many parts re-plated with a tin/lead finish over their matte tin finish to comply with contract requirements. Most commercial off the shelf parts (COTS) are no longer available with anything but matte Tin, or other RoHS finishes. Many vendors changed finishes without any notice, creating havoc in our stick room.
The EU Lead regulations came about when the CRT was king and the glass screen in front of the CRT was made of heavily leaded GLASS -- yep similar to the heavily leaded glass "crystal" that some EU countries are so proud of for wine glasses! The amount of lead in the electronics was minimal compared to the lead in this glass, which was usually broken up and sent to the land fill. Of course the problem is going away pretty fast since the CRT is going away! LCD displays don't have or need the leaded glass -- they are not first cousins to an X-Ray tube! Oh, the single BIGGEST source of Lead getting into the environment is automobile batteries -- and no they don't have lead free versions of those (well they do, but the cadmium is worse!).
Yes, "newer alloys" are better. Tin whiskers can appear before your eyes. I've recently seen a whisker grow between two tin plated component leads while I watched (under a high power microscope). While I use new CuAgSn solders, many of the "RoHsS complant" parts I buy use pure tin finishes on the leads and there are no other finishes available yet. Classic Tin/Lead solders producted joints that were easy to visually inspect - the shape and surface texture of a good joint were fairly unique. Modern non-leaded solders produce a variety of lumpy grey results even when carefully applied. Aiding an abetting the RoHS issues are the use of fluxes that are easily cleaned without CFCs. Old school rosin based fluxes worked well and left beautiful joints - but were nearly impossible to clearn off without CFC based solvents.
My understanding was the conformal coating doesn't stop whiskers from forming. Small whiskers can simply grow straight through the coating. Besides, most conformal coating processes are designed to keep hands or screwdrivers or loose wires from shorting the circuit board by touching it. It isn't obvious to me that the conformal coating gets between pins and underneath pins in such a manner that would stop all possible whiskers from shorting to all possible nasty locations. Can conformal coating even get underneath the leads of an LQFP package (with 100% coverage)? A BGA package?
Conformal coatings may mitigate risk, but I don't think they are a "solution". Also, the performance of conformal coatings probably varies widely with type and quality of the coating and quality of application. Conformal coatings are in the category of "any manufacturer that cares enough to get the conformal coating correct, probably also knows enough to get the tin-replacement solder chemistry correct and avoid the problem in the first place."
I think we have to worry about the cheap subcomponents from relatively unknown factories being assembled into larger subsystems that are in turn assembled into larger machines/products/cars/etc. To have a quality problem, we only need one whisker on one circuit board, and there are lots of circuit boards in most machines (and most other devices too.) The "not checking the suppliers" problem is what caused the leaky electrolytic capacitor problem. It only took a few inexpensive capacitors to cause lots of computer problems.
So even if they get to use leaded solder, they can get whiskers on their components...
- "History shows again and again how nature points out the folly of men" -- Blue Oyster Cult, 'Godzilla'
I guard my rosin core solder like it's gold. I cannot stand the lead free solder.
What made me laugh one night was when I was at the local DC401 group and we were assembling the RGB light kits. A few of the guys had vented soldering stations and warned to "wash you hands" after handling leaded solder.
It was then that I brought up that if you lived in any area that was built up from the 19th century, more than likely your water distribution was via lead pipe. Not to mention the environmental lead you're exposed to every day.
The hand washing is probably a good idea, and not inhaling the fumes might be helpful.
But hell, I've been soldering stuff with lead based solder for many years. Maybe it explains why I'm so deranged.
No. lol I must agree with parent and say, he isn't flame baiting.
Wikipedia works well as one of the first sites to go to for information. But it is no Silver Bullet and should never be one's only source.
I believe a newspaper writer based an article on information in a Wikipedia article only to discover (after it was published) that the Wiki had been vandalized. The most the most amusing modification stated that the person they were writing about had died. I'm sure the writer was surprised when he got an angry phone call from his supposedly deceased subject matter.
A watched article is safer, but still not something that should be blindly trusted.
It occurs to me that this debate has lots of comparisons with the current minor furor over the rise of multiple CPUs. Many in the programming industry are despairing because we are being forced to design software that runs on multiple CPUs at once, rather than just getting more CPU speed. And again, it's due to externally imposed constraints. In the automobile industry, the catalytic converter was that constraint, in the lead electronics debate, the RoHS is that external constraint.
In the programming world, I expect things to be resolved the same way: by superior engineering, taking advantage of the mountains of research and practical application of parallel processing designs that have been going on for decades. My favorite language Python is particularly sensitive to this debate due to something called the GIL, but solutions abound, including the newly accepted pyprocessing module or any number of things you can do with Twisted, both of which stand as examples of better, practical engineering taking advantage of known solutions to the problem.
Engineering fixes most problems that changing standards and regulations cause, eventually.
It's rare that you're presented with a knob whose only two positions are Make History and Flee Your Glorious Destiny.
These are completely immune to tin whiskers.
I would be supprised if silver grew tin. Technicaly you are correct, Silver doesn't grow Tin whiskers.
Silver whiskers is a real problem in industrial locations where Florene is present. The circuit breakers, buss bars and other industrial power components are prone to growing Silver whiskers. Failures are the result of increased contact reistance causing failure from overheating and arc flash failures from arcs initiated from the short. Both are serious failures.
Refrence with photos, Of course:
http://nepp.nasa.gov/WHISKER/other_whisker/silver/index.htm
The truth shall set you free!
I just went to the trouble of buying a temperature controlled soldering station so I'd have better luck transitioning to lead-free solder, and now I read about the problems with tin. So, what exactly is the implication for hobbyists? I'm soldering radio and power circuits. The solder I just bought from Radio Shack is labeled "Lead-Free Silver Bearing Solder 96/4". Does that mean it's 96% tin and 4% silver? Will my radio and power circuits be affected by the tin whiskering problem? Should I go back to lead-full solder and return my Weller soldering station?
The Ford EEC IV engine controller from the 1980s was designed for a 30 year life span. (My 1985 Bronco still has its original unit.) No software updates, either; the program was masked onto the custom CPU chip. Never needed a recall. On the other hand, my 2007 Jeep Wrangler had three separate major software updates in the first year.
Plenty of industrial hardware needs to be able to run for 30-40 years.
Jenkins Valves used to boast of century lifespans. They had pictures of a valve installed around 1900 which had been removed during a water line replacement. It was still working fine, and after a few months of being photographed and shown off, it was re-installed in a new water line.
hat is, no one ever really knows anything about the Universe other than what they're told, and what they can work out in terms of internal consistency checks on what they're told.
I have to disagree with this statement. Science, properly applied, gives mankind the tools to know things based directly on his or her experience.
The beauty of good science is that you DON'T have to trust someone else's eyes. You can trust your own. While you may not discover the Higg's Boson or some other exotic subatomic particle in your own home, there is a surprising amount of fairly important experimental evidence that is cheap to do, that you can do yourself.
Take for instance the solar system. Sure, Ptolemy could be ok if all you wanted was planetary timetables, but, then there's the occasional cases where they would be wrong, and for increased accuracy, you need Kepler for the ellipse and then Newton ultimately for calculus based gravity, and then when you want to get really accurate, you need Einstein to consider various relativistic effects. In each of those cases, the edges are well defined and serve as a model of where to look, and in all of the above cases, all you are doing is taking a decent telescope and a CCD camera and seeing where things are in the sky.
Even at the smaller levels of physics, you can decide for yourself. You don't have to say that you are not sure if Maxwell or others were on the mark - you can take iron filings on top of a magnet and a piece of paper, move the thing around, and see that, yeah, all he's doing is describing in calculus the field that you see. You can follow in Einstein's footsteps and see the photoelectric effect by yourself - with a simple solar cell. You can perform the double slit experiment with sand and with water and then even light, and that's basically going to give you a pretty good heads up on quantum physics. Even the gold foil experiment is probably not out of reach for the determined amateur.
This is my sig.
In order to gain RoHS (?) compliance they have lead free solder in the system, rumour has it that this (amongst other issues also) is one of the reasons the machine has issues.
Obviously there's a heat / warping problem and the board is rumoured to bend at high heat, none the less the solder has been listed as a problem too.
Oh by the way SOUL-DERR
SOULLL-DER
NOT 'sodder'
I'm so happy to see you ask this question.
As I've pointed out several times, it can't be trusted. It's only as accurate as the last person to edit it and you have NO way to know if the last person was an idiot, a corporate sponser or someone that actually knew what they were talking about. That said, let's dissect a bit further - those of you that consider yourself experts in your field - how many of the people around you in that field do you actually think know nearly as much as you do? Exactly.
And of course once the subject becomes a little bit fuzzy (global warming, Iraq war, oil drilling) all bets are off with the liberal edit most likely winning (or the points of view of the various 'neutral' overlord editors).
EK
I think that this might be partly because, by the time a lot of this stuff breaks down, it's somewhat obsolete and a new, bigger model is out.
27" TV breaks after 3 years, don't worry, now you can get a 32" for less than the old one cost.
Your 1.6Ghz Pentium-M laptop died... no worries the new Dual-Core Centrino is $100 less and a whole lot faster.
I find this happens a lot in terms of computer hardware. I have a 2.8Ghz P-4 laptop myself that has been kicking around for longer than expected (HP Pavillion zx7000): drive still works, no dead pixels, etc. I've been thinking on getting a newer laptop for quite awhile but for now I think I'm just going to keep this one until it dies.
To be fair, I keep good care of my machine by regularly dusting it out to make sure all the fans are running, not blocking the intakes etc. After seeing how a lot of people handle their electronic equipment I'd say that cheap manufacture is only part of the problem.
Really the Wikipedia article says the jury is still out. Since the tin whisker problem develops over time and the formulations that meet ROHS are new, we have no idea how it will play out in the coming years.
I wouldn't be at ALL surprised if ROHS creates a sort of landfill doomsday in a few years where the levels of electronic waste skyrocket due to failures.
The real way to be more green is to ban crappy gear that ends up in the landfill after a couple years. Want to cut hazardous landfill by 2/3? Make the useful life 3 times longer! Take the weasels that build in obsolescence and actually expend extra time and money to make sure the existing device can't be upgraded out back and shoot them (with steel bullets so we don't pollute the graveyard :-)
Imagine the number of devices in the landfill just because replacement LCD screens are made of pure unobtanium or very deliberately priced just below the cost of a whole new device (or occasionally MORE than the cost of a new device).
I've eaten a fair amount of silver in my day, with no harm done. Hindus eat a lot of it too. And I've applied silver-based cream to burns (makes 'em heal faster). Westerners used to mark cattle by slipping a silver dime into a cut, that way you could check with your fingers to see if somebody had re-branded cattle they'd rustled from your spread.
Silver's a doddle. And there most certainly is plenty of documentation and research on lead leaching into ground water.