Slashdot Mirror
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.
> but can we trust Wikipedia?
No. lol
Where in the summary/linked articles is it suggested that tin whiskers are a fiction?
I'm driven away from main-stream sites by the lack of rigor. The more Slashdot loses its nerdy focus on the technical details, the less reason I have to visit it.
"Be light, stinging, insolent and melancholy"
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++;
bLnark's FUD - Fact or Fiction?
Today's lucky number is: 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0
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.
Most made the switch in advance, I guess due to shelf-life of products and ironing out problems working with the new material.
/. so much!
So that's what they put in there instead, good to be in the know! These little hints in the summaries are what makes me appreciate
Power corrupts the few, while weakness corrupts the many.
If you don't trust wikipedia, then change it! That's the whole idea behind wikipedia.
/. ID #644805
This insightful comment brought to you by Forest Grump -
Tip: Do not change it using your home/work computer. It is best to change it from a public library in a city far far away.
Tip #2: Don't buy a plane ticket to travel to this far far away city. It is best to hitchhike so you can save on travel $$$ and not leave a paper trail.
Is it true that more people vote for the winner of American Idol, than vote for the president? -Ali G.
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.
My GSD eats a cat a day.
Check the reference yourself.
What? No references? Add citation needed or better yet, do some research and find a citation that supports the statement.
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
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
http://www.usatoday.com/tech/products/gear/parts/2007-10-05-tinwhiskers_N.htm
2007....
The man has never said anything sensible, well, ever.
"XML is like violence. If it doesn't solve your problem, use more." - Anonymous Coward
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.
(body)
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.
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!!
I think you've wasted your time commenting on the comment.
I like his story about replacing all the car parts on his old Thunderbird. If it is true of course. Probably has been driving the latest BMW models for the last 10 years.
He mentions silver and bismuth are just as bad for health. Checking the equally reputable Wikipedia page for silver yields "Silver plays no known natural biological role in humans, and possible health effects of silver are a subject of dispute. Silver itself is not toxic but most silver salts are, and some may be carcinogenic." So seems to me at least, one cannot compare silver and lead in terms of health effects. No one disputes that lead is bad for health, particularly the health of children. Checking on bismuth also yields no known health maladies other than perhaps discolored teeth from ingesting it. Again compared to lead it seems tame.
Also a quote from Cringley's article, I love the type of logic it displays :
"mean time between failures (MTBF) has gone down (accelerated MTBF tests, which are the only MTBF tests we do anymore, don't reliably pick this up, by the way), and reliability has suffered."
So basically "I am right but you can't tell, because the ways of things are measured now hide the fact that I am right"
The mechanic blamed the failure on lead-free solder. It sure did hurt my wallet.
putting the 'B' in LGBTQ+
And, sorry, it may cause brain damage, when I grew up, the soldering iron was my sonic screwdriver, and 'flux' should be available as a room scent; I associate it with many happy memories. (Well, also with burnt fingers and exhausted frustration as expensive parts utterly failed to work at the 11th hour, but still. .
Ground-up ESTES rocket-engine powder is one of the others.
How did Heston put it. . .
-FL
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 ----
Too bad he is serious, as the problem really does exist.
Now, on what scale is debatable, but not the problem itself.
---- 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.
I don't know about the majority of tin whiskers, but some of them sure are visible. Just do a Google image search for them. I do not know how common the problem will be in new electronics but some people have sure had trouble.
-WolvesOfTheNight
Tin whiskers are nothing less than a gift from God. It is merely left up to us to discover the nature of His gift to us, and to take advantage of it.
The question we should be asking ourselves is, what potential uses might these tin whiskers have? Are they good for anything? Can we sell them in some sort of product and make money? For example, can bald guys plate their heads with tin and start regrowing hair?
These days everything electronic is slapped together on assembly lines in third-world crapholes. How are we supposed to know the difference between tin whisker failures or the device being made with adulterated materials in a factory full of former cabbage farmers?
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"?
--Which just goes to show that life is stranger than fiction. Except when it's a Doctor Who episode.
-FL
You can have my leaded solder when you take it from my warm tinned iron.
I've worked with both leaded and unleaded solders. For hand work, nothing beats good old 60/40 Pb/Sn, but some lead-free solders are much worse than others. The ones with a little bit of copper or bismuth are somewhat better at wetting components. Unfortunately, most solder manufacturers just say "Lead-free" on the label, so it's hard to tell (at the retail level) whether you're getting "really annoying" lead-free solder or "not too bad" lead-free solder. My advice is to find a brand that works with your iron (and/or preferred temperature range) and stick with it. And to keep a spare set of soldering iron tips around, with a few pounds of leaded solder in the closet.
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.
Fact or fiction... I don't know. All I know is that "Tin Whiskers" is an amazing cat name.
"Things are more moderner than before- bigger, and yet smaller- it's computers-- San Dimas High School football RULES!"
I for one welcome our new tin-whiskered overlords.
__
Men with no respect for life must never be allowed to control the ultimate instruments of death.
GW Bu
Next time my cords fail "invisibly" I will look closer.
I was beginning to wonder why simply unscrewing and rescrewing the plug-case from the plug proper would fix the short. There is no visible short - but "visible" is very different when you're trying to get notes to happen and not caring about the specifics of the failure mode.
I guess it's again time to make my own patch cords with gobs of politically incorrect lead-tin solder.
"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."
DOESN'T QUALIFY: I've been to the JPL open houses and discussed the tin whisker problems and looked at the photomicrographs and JPL has been designing spacecraft circuitry with an eye to avoiding this problem for a long time.
Anyone who doesn't know about this is not in the military electronics or satellite business.
In cars solder joints are rather far apart as most vehicle electronics are not as complicated as your average Enterprise grade server. As the distance between the solder joints narrows and when you have 10 high speed fans blowing air through this rather dense device the probability of a whisker causing a dead short is much higher. What is more scary than tin whiskers is zinc and other alloy whiskers from rack hardware and screws being sucked into the fans.
Many datacenters ban sawing drilling and any kind of metal or material cutting on the data center floor for this very reason. Any particulate matter is going to be sucked right through the servers and has a high probability of hitting the wrong places and causing shorts or even worse being trapped inside the server and causing cooling issues.
Does a conformal coating stop the whiskers from growing?
According to the last RoHS-is-stupid thread I read on Usenet, yes. Conformal coatings make rework messy, though.
Tin whiskers cause failures, and failures are good for business if you are in the troubleshooting/repair field.
Steve's Computer Service, Hobbs, NM
Why wouldn't it? The conformal coating will provide a physical barrier to the tin whiskers. They would be too fine and not have enough energy to penetrate it.
I think the military was onto something by demanding much of their electronics have it.
Take the cheese to sickbay, the doctor should see it as soon as possible - B'Elanna Torres, "Learning Curve"
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 effect. Say it back.
Eeeeeefect.
Now please look up the definitions of those two words and write them on the blackboard a hundred times before the start of Monday's class.
Lead free solder makes it more difficult to manufacture boards reliably. They require much more post assembly inspection and lots of touch up work done by hand. The industry is adapting, as expected, but not without it's fair share of bitching and moaning. Lead free solder does have known reliability issues and that is why military and aerospace is exempt from RoHS. As someone who designs PCB, I deal with this issue a lot. It is a pain, but it is just one more problem that needs to be solved, and it will be.
How the mighty has fallen. Reduced to making bits of plastic; and that not very well!
Engineering is the art of compromise.
She reached legal drinking age this year (21 where I live), but so far she's been very responsible with her drinking. (Probably has something to do with the price of gasoline).
Except when he predicted that pretty much nothing was going to happen with the Y2K switchover, despite the fact that most "experts" thought we were going to have massive computer chaos on a global scale.
And just when I thought bovines were halal, too...
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.
...this isn't about a movie with a giant robot cat?
Phooey.
The military specifically prohibits the use of lead free electronics for their applications. It is becoming increasingly problematic, as most commercial providers are going lead free to meet European requirements. Lead free substitutes are great for the consumer electronics industry, as experience suggests that a reduced life expectancy of 2 to 4 years is great for generating a replacement sale.
Hey! That's me! My ignorance is justified for once. Cool!
-FL
Banned leaded gasoline: that was a good idea. But this may be a bit over the top. Sure, we should minimize the amount of heavy metals in our environment: but last time I checked PCs were recycled (at least in my hippie town) and kids don't lick microprocessors and circuit cards.
Tin whiskers is very real. I've seen electronics fail from them and it only requires a Tin-Lead solder, not pure to do it.
However, the voltages today tend to blow the whiskers like a fuse, thus negating the issue.
the man who types with bionic fingers.
Protective coatings on circuit boards prevent corrosion and whiskers. As a hobbyist, I use lead-free solder and liberally spray every board I etch with a conformal coating. It also keeps them nice and shiney. The only thing left exposed are connectors.
Most consumer electronics have protective coatings. But they don't have a conformal coating on flexible leads, because it chips & cracks there. It also isn't used on heatsinks (to my knowledge), because it can insulate them or burn off.
The tin whisker phenomenon is absolutely real. Whether it is a problem for a particular application depends on a number of factors, including the cost of failure, the likelihood of failure based on the specifics of the design, etc.
It is an extreme problem in military electronics because both the likelihood and cost of failure rise for several reasons. Military electronics are, indeed, expected to operate for decades, the types of maintenance that can be done do not fix the problem, and the types of repair required on failure are fairly expensive. (Assuming failure does not result in crash and burn.)
The particulars of military make whisker-shorts fairly likely, and the cost effective solution, so far, has been to use the solder that works instead of the solder that doesn't. (As other posters have noted, there are some lead-free solders that avoid the whisker problem, but cause others. One is the identification of a good solder joint. Another is eutecticity. Yet another are the melting and reflow points; understand that complex assemblies undergo multiple solder and temp cycles and using a high temp solder after a low temp solder is a sure recipe for disaster.)
The real devil of a problem is subcontracted designs from commercial-oriented contractors. In practice, there's nothing wrong with leveraging commercial talent, but in practice, they don't always realize or take seriously the no-lead-free dictates under which the military industry operates. This translates directly into migraine headaches for design engineers and the logistics departments of the big four military contractors.
And the gut-grinding aspect of this is that electronics do not use that much lead to begin with. A typical turn-of-the-century PC board used around a gram of solder, of which less than half, typically, is lead by weight. That's a tiny amount-- about a thousandth of a pound. Annually, lead consumption due to solder is much less than one percent. (Compare to storage batteries, though, which is up around 75%.)
These are not problematical amounts of lead.
The only thing that's been overhyped, here, is the dangers of lead-based solder.
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'
First, the cause of tin whiskers is not known precisely (well, nobody has told me yet), but they are REAL.
They have only been observed on tin-plated copper (or brass). Most likely, this is because the copper-tin intermetallic is less dense than either copper or tin (most intermetallics are denser than the constituents). The mechanism is not confirmed, so this is not certain. Furthermore, whiskers are only seen on fairly thin tin coating, such as plated coatings.
Billions of tin-coated ceramic capacitors etc. have been manufactured and installed with no report of tin whiskers (both with RoHS and non-RoHS processing). Whiskering is rarely observed on tin soldering - the coating is too thick. Rare cases are further reduced by choice of tin alloy. There is still no agreement as to the best alloy, which is not surprising, it took about 50 years to standardise on a tin-lead solder.
Whiskering is not dendritic growth. This is caused by inadequate clearances. There are a few simple additional precautions required with tin solder processing, and some parts will not withstand the higher-temperature processing. Overall, I have not had reports of more process-related failures with tin soldering, but it is early days yet, and my experience is with low to medium volume production.
Some coatings are resistant to whisker penetration, the most commonly used type is not.
Hope this helps.
is they're a bitch when the cat rubs up against my leg.
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.
She reached legal drinking age this year (21 where I live), but so far she's been very responsible with her drinking. (Probably has something to do with the price of gasoline).
I know gas prices are high, but if you want to keep her sober, don't give her any of those ethanol blends.
When our name is on the back of your car, we're behind you all the way!
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.
Conformal coat doesn't seem to completely stop tin whiskers, but it will help reduce the odds that they will cause a problem, just because the conformal coat can help to deflect the whisker. My understanding is that we currently don't understand the full mechanisms that causes things to happen well enough to know for sure that we have stopped them, other than the time tested method of lead poisoning the tin finish. One thing with a mitigation scheme like conformal coat is that if it is too soft it won't do much to bother the whisker but if it is really rigid, it could create a localized stress and these stresses are what tend to cause the whisker to form in the first place.
I'm not an expert on this, but I do work in an R&D organization at an avionics company and frequently help out our guru on the topic with data analysis and reviewing papers in tin whiskers and lead free assembly. Not sure if it is published yet, but I did see an industry paper on this that I believe was being done with the CALCE consortium at the University of Maryland.
Unlike Cringley, said "experts" often had a lot of consulting fees riding on the perception of a global Y2K crisis. At least it made the COBOL folks feel important for a little while.
Please stand clear of the doors, por favor mantenganse alejado de las puertas
Just about every living and formerly-living species has or could have at least a stub in Wikipedia, and I would expect no less from a bookshelf-sized paper encyclopedia.
I venture that 90% of these articles are not heavily watched.
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
You don't have to. The lead leaches from the city dump and is deliverd to your Mountain Dew bottler and delivers it.
For non slashdotters, your pure spring bottled water. Most bottled water has fewer safety checks than tap water. Heavy metal contamination often discovered by municipal water systems where bottlers don't check.
The truth shall set you free!
Rusted.
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?
I work for a major supplier of electronic components and YES, without a doubt, whiskers are real (I've tested the parts my company makes and all of our competitors and we all grow whiskers on straight tin plated parts). Want to know why everyone is ignoring whiskers? Money and legislation. It costs money to run two different plating lines, so the Pb containing lines are being phases out and Pb containing parts are not being made in large volume. Companies are charging premiums for tin-lead plated finishes to the companies that have lead free exemptions. Money makes the world go round and if you can charge more or spend less you are todays hero at the price of tomorrows ability.
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.
Drive-by-wire can be done properly. If it's good enough for large passenger planes, then it's good enough for cars. Although, the two industries are quite different in the way they do things (costs, redundancy, etc). Still, it's seems to be creeping more often into the auto industry, too.
You gotta give those guys credit for planning their retirement:
1. Introduce Millennium bug
2. Wait till 1998
3. Become consultant
4. Fix millennium bug.
5. Profit!
"XML is like violence. If it doesn't solve your problem, use more." - Anonymous Coward
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'
Tin Whiskers ?
I have Philips radio from 1939. Nothing special. Long waves, medium waves, short waves, bakelite case, quite small for tube radio. It still works thanks to the leaded thin soldering alloy. It just needs to be kicked hard sometimes because it tends to make whistling like noises.
Thin Whiskers !
Stop kidding me, if such thing existed, my radio would stop working 50 yeas ago.
The only reason why RoHS is so much enforced is throw it to the landfill recycling policy for the modern electronic.
This is already done in europe under the WEEE directives. As an electronics retailer, we are bound to accept any product that we have sold back for recycling at the end of its life. There is a requirement that the customer have their reciept, but otherwise it's pretty straightforward.
The problem is that this cost is borne by the retailers, not the manufacturers, so any pressure on the manufacturers to reduce that cost will come from retail - and in the case of larger companies like HP or Samsung, we need them more than they need us.
Is it possible that whiskers grows because the metal has quite abundant different isotopes?
That may cause an imbalance in the crystal structure of the metal and gradually push out the lighter isotopes when the metal is subjected to vibrations, stresses etc...
Just a thought, I'm not qualified at all to talk about metallurgy, but...
Moderation is overrated.
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 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?
If course not! I left my cat alone with wikipedia and wikipedia huffed it!
Never trust wikipedia. It'll huff anything.
mcgrew's razor: Never attribute to stupidity that which can be explained by greedy self-interest
"Encyclopedia" is to "Wikipedia" as "Library" is to "Line of people at a bus stop".
You're right. Aerospace has been doing it, starting with the military, for 30-40 years now, but I just don't trust the auto manufacturers/ You'll have 30 different companies making 30 different types of systems....frightening. Drive by wire gas is fine. Drive by wire brakes is not.
We were going to have massive computer chaos on a global scale until all the important stuff got fixed. Come the end of 1999 I don't recall most experts saying there would be chaos, because thy knew the huge effort required to fix all the systems had been made. The fact that Y2K was a damp squib isn't evidence that there was never a problem, it's evidence that the problem was fixed in a timely fashion. It was fixed precisely because the experts made a fuss about it.
Chernobyl 'not a wildlife haven' - BBC News
In the satellite business, we've known for years about tin whiskers. When lead-free parts started becoming common, the problem started showing up in instruments built for NASA.
In one case that I read a report on, a tin whisker grew a distance of an inch or so and shorted a power supply connection. So, it's a real phenomemon and a real concern.
Tin whiskers (crystals, really) grow out of a pure tin surface, especially one subjected to mechanical or thermal stress; they will grow right out through plastic conformal coating on a PC board, and can grow to a length of inches. They can short adjacent connector pins, break off and float around in high-voltage supplies under zero G, and generally be a nuisance.
ANY part (electrical parts, sheet metal, connector shells) with a pure tin coating can grow whiskers.
Alloying the tin with lead or antimony (think, solder-dipping tinned leads in tin/antimony solder) will prevent whisker growth; conformal-coating your PC boards after assembly will also help (won't prevent whiskers growing OUT, but will keep them from touching exposed conductors).
Incidentally, tin is a pretty weird metal in general; it has a powdery gray non-metallic phase that is stable below 13.2 degrees C (Google "tin disease"), and there have been cases where tin items (such as tin church organ pipes) have spontaneously crumbled to powder in cold climates when the metal underwent a phase change to the nonmetallic state.
"My strength is as the strength of ten men, for I am wired to the eyeballs on espresso."
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.
Well, where do you think HAMburgers come from?
Nasa also has information and research into this: http://nepp.nasa.gov/WHISKER/
My girlfriend is doing her PhD on tin-whiskers. True: Tin whiskering is not fully understood, and studies suggest contradictory causes of whiskering. But whiskering _is_ a very real phenomenon, certainly in the realm of "Fact" and not "Fiction".
After that happens, it might cost you twice as much to fix as you'd spend on a newer, better set.
TVs from before 1960 are generally black & white, anyways. My family still had the only color set in our neighborhood in 1962, and I knew plenty of people still using B & W sets in the early 70s.
Now, those telechron clocks, those last forever.
I believe to be effective, tin foil hats must be made out of silver foil -- or at least the wearer must believe that it's silver foil (although the roll says aluminum foil).
"If it's good enough for large passenger planes, then it's good enough for cars."
Only if they get identical inspection and maintenance!
Aircraft are maintained by AMTs or equivalent who are trained and experienced. Strict maintenance and inspection schedules are (supposed) to be followed. Almost no one does a preflight or postflight or phased inspection in their wheeled vehicle.
This is not remotely how the average schlub maintains his car or truck.
(I speak from plenty of aircraft experience to, including 21-ish years of F-16 maintenance (engines and crew chief).
"This post is an artistic work of fiction and falsehood. Only a fool would take anything posted here as fact."
The whiskers will punch right through the coating as if it didn't exist.
Awesome. Um... does that have something to do with my post? :-)
Don't forget the media and pretty much everyone else said there was going to be chaos. Cringely got LOTS of emails about the subject at the time, most of them pointing out how wrong he was, and that the world was indeed doomed. My point was that Cringely HAS said something sensible.
Take back off television, switch on television, switch off room lights, thump television, look for little sparks. That's how it's done.
http://www.semiconductor.net/article/CA170390.html
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).
* JEDEC/IPC JP002 "Current Tin Whiskers Theory and Mitigation Practices Guideline" (http://www.jedec.org/DOWNLOAD/search/JP002.pdf)
* JEDEC JESD201 "Environmental Acceptance Requirements for Tin Whisker Susceptibility of Tin and Tin Alloy Surface Finishes" (http://www.jedec.org/Catalog/catalog.cfm)
Further work is ongoing within JEDEC, IPC, iNEMI, and other groups to further refine industry practices. See http://thor.inemi.org/webdownload/newsroom/Presentations/Sn_Whisker_Symposium_2008.pdf for one example of this.
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.
most military electronics are "entertainment systems" for the brass.
"National Security is the chief cause of national insecurity." - Celine's First Law
The main issue when discussing Tin Whiskers is the confusion with several reports from 10+ years ago reporting how dangerous Tin plating is. And yes, the Tin plating they tested were very bad, and potentially dangerous in important situations.
BUT,
This is not the same as what is being used now. The knowledge manufacturers have now is much more than before. There are additional procedures in the plating process to reduce the chance of whisker growth, the plating and under-plating are also different then before to improve overall performance and whiskering.
Can whiskering occur now, Yes, but what is being seen now is well under 50Âm. This size of growth is no true concern for most applications, the exception is for very high density ICs but Tin isn't normally used anyway.
The main problem with this new RoHS is not the whisker growth but the effort needed to properly evaluate a new plating material and process. In the early days of RoHS there were several reliability issue from manufacturers simply dropping the lead from their line without evaluating or testing their pin connections properly.
So does Tin Whisker occur, Yes, is it a problem, now with proper care and testing.
Yeah, I did kinda point that out, probably not clear enough. Also, and I could be wrong here, but electronics generally aren't checked in the same way a mechanical components are, right? Do aeronautical engineers take apart the electronics and manually inspect each component on the PCB? My impression was that they relied on redundancy and well designed systems instead. Electronics are generally supposed to reduce maintainance over mechanical systems.
Also, there is no reason there can't be more strict servicing schemes for cars that need them. The new Accord has a accelerator by-wire system. Although, as the above poster mentioned, brake-by-wire probably won't be coming anytime soon. Although, steering may soon be at least partially by-wire.
The whiskers grow from the base, are very sharp, and stronger (per unit cross-sectional area) than any polymer coating.
Thus, the growth isn't affected by whatever you put on top, and conformal coatings won't stop them.
One thing that seems to help a lot is an annealing step. They sppaear to be caused by the formation of large-volume copper/tin intermetallics at the coating boundary, and a post-plating bake (something like 150C for a couple of hours) forms a simple stable intermetallic layer, while at room temperature, the intermetallics grow along crystal boundaries and create the compressive stresses that lead to tin whisker growth. STmicro has some papers available on the subject.
you guys are nerds get a life.
nobody cares about tin whiskers...most people dont even know what they are.