Here's where I have to chime-in with a reality that people have yet to experience and most don't know about: The unintended negative consequences of RoHS.
I have over a dozen instruments and several tools that are, in some cases, over 30 years old. I think all of my scopes, signal generators, DVM's, logic analyzers, DSO's, probes, lab power supplies, etc. are pre-RoHS and, in most cases, significantly so.
The transition to RoHS, while, in principle, well-intentioned, is likely to prove to have been a massive mistake.
Lead-free solder has one major problem: Tin whiskers.
One way to think about this is that all RoHS electronics has a stochastic failure rate. I have devoted more time than I care to admit studying tin whiskers in the context of my work in aerospace. I have, in that process, consulted with NASA scientists who were are the forefront of long term research on the subject. The most salient take-away was that we had no way to predict or truly mitigate tin whiskers. The only mitigation in aerospace is to, quite literally, send chips to services that remove all lead-free solder from the pins (or remove balls from BGA's) and replace them with conventional lead solder.
If this plays out as it could, landfills are going to be piled sky-high with broken electronics. From phones to laptops, TV's, ovens, clocks...anything really. And cars, yes, cars!
Lead-free RoHS solder is a ticking time bomb and, in my opinion, one of the most misplaced decisions made in the name of protecting the environment.
I have HP-41 calculators I bought in the early '80's that still work as new today. That's to say they are nearly 40 years old. There is no way a RoHS compliant calculator will survive 40 years. That is nearly impossible. And so, millions of them will end-up in landfills. Well done European Union, you really helped the planet with that one!
For those not familiar with RoHS issues (a deep and wide topic), here's a starting point:
Ideally, we would be building devices that don't suffer from tin whiskers in the long term. Pragmatically, the vast majority of e-waste is being generated from simpler failures than tin whiskers (degraded batteries, simple mechanical breakage, changing standards and performance requirements, etc). In that case, it is better that the supply chains for those products are lead-free, reducing harm in production and in disposal.
We need to make our consumer products longer lived and circular, and that should be a prerequisite for RoHS exemptions (as it is currently for certain classes of long lived non-consumer devices).
Funny, the simplest thing to do there, and relatively cheap, is to lacquer the whole device after it's soldered. This is done on military grade hardware - or even tougher conformal coating.
Sadly, no, this does not avoid or stop tin whiskers at all. The general technique you are referring to us called “conformal coating”. It can help a bit but it does not stop growth. Also, at that scale the whiskers are super strong and easily puncture right through the coating.
This is a deceptively complex topic (as I learned over the years). For example, a whisker that does not penetrate the coating will either buckle and curl-up under the film or grow laterally under it. With fine pitch components having pin-to-pin gaps in the range of 0.25 mm, a short between pins can happen in just a few weeks.
Conformal coating is useful for other reasons, but, ultimately, it isn’t a solution for tin whiskers.
Back in the day I even looked into using specially formulated epoxy encasement. What starts happening there is that the coefficient of thermal expansion differential between The epoxy, board and components can cause all kinds of failures...and it still does not stop tin whisker growth or buckling.
This is fascinating, I'd never heard of tin whiskers before today. From a short look at the literature, nickel-palladium-gold alloys seem to be an alternative lead-free finish that doesn't suffer from whiskers. Have you worked with that at all? Does it have other shortcomings?
Well, being that most of my work during the last few years has been in aerospace we just use conventional lead-containing solder. When you can't afford for things to fall out of the sky you go with what you know works. We've known about tin whiskers since, I think, the 1940's. In fact, if I remember the history correctly, we added lead to solder precisely for this reason way back in the prehistoric era.
I might be diving into some industrial work soon that does not benefit from RoHS exemptions in this domain. This is one of the important cards in my kanban board...likely a rabbit hole that will not be pleasant to navigate.
I took a quick look myself. Here's a note from Maxim with interesting data:
I've used pretty much all the conformal coatings they list in this article. What they don't go into is buckling under the coating, which can short adjacent pins in fine pitch chips.
I truly hate this problem. I has wasted more of my time over the years than anything else. RoHS is, in my opinion, a very misguided directive. It's a perfect example of when politics gets ahead of reason and fear-mongering wins over science. If we are not careful we are on track to do something similar with climate change.
> Funny, the simplest thing to do there, and relatively cheap, is to lacquer the whole device after it's soldered. This is done on military grade hardware - or even tougher conformal coating.
That helps avoid tin whiskers, but those aren't the only problem with lead free solder. It doesn't flow as easily as tin-lead, so dry joints are more common. It's relatively brittle, so it's more susceptible to vibration and thermal fatigue. Melting point is higher so components are more likely to be damaged during soldering.
Military hardware is exempt from RoHS for good reason.
> the vast majority of e-waste is being generated from simpler failures than tin whiskers
I can't assert or challenge this conclusion because we simply do not have the data. This is yet another reality of this issue: Tin whisker failures in the consumer domain are nearly 100% unreported.
Consumers are certainly not in a position to conduct the forensic work required in order to determine failure modes. My guess is that the large majority of devices are thrown out upon failure, which means we know nothing about why they failed.
Companies, on the other hand, frankly, have little incentive to conduct that research other than to use best practices during design. If a product survives a couple of years they are good. This isn't due to some dark profit motive, it's just a reality of business. You simply can't ask every single customer to send you their failed hardware for expensive --very expensive-- forensic analysis no matter their age or condition. This would mean having to manage a process involving forensics of millions of devices per month or year, depending on scale.
When I was investigating tin whisker mitigation options I explicitly sought out data from the consumer electronics domain. I quickly discovered there was none, at least nothing useful. This is why I don't think a statement such as the one you made is neither right or wrong, it simply has virtually no supporting data in either direction.
I should rephrase. From my experience in consumer electronics, the vast majority of instances of consumers stopping using a device are not from unknown failures. They are from visible failures (including reduced battery life), software/content incompatibility or obsolescence, or the consumer just generally losing interest in the device. I should caveat though that this is in PC and mobile categories. It’s plausible that things like appliances don’t fall into those failure or obsolescence modes and could be facing unknown failures that are solder related.
Yeah, it's hard to quantify in any meaningful way. That's why I said I am not in a position to confirm or challenge what you said and all I know is that, for the most part, we can't really make scientifically supportable statement about the consumer world (by this I mean with actual published data from an authoritative source). We are blind.
In 1992 I got a Swatch "Earth Day" edition self winder. Made from the best modern earth friendly materials. By 95 it had cracked and yellowed to the point it was illegible.
I started wearing my grandfather's '68 Caravelle self winder. I still am.
I had heard about tin whiskers, but always in relation to NASA. I had assumed it was only a problem in space, somehow related to lack of gravity and/or atmosphere.
Apparently it's just that NASA cares about reliability more than most, and hence takes the time to do more detailed failure analyses.
NASA has done tons of research on this over decades. I have read most of the papers they published and worked with a couple of their researchers. While the context was aerospace, the effect happens on earth just as well. Pretty much all of their tests are done on the ground.
The reason lead was added to solder in the ~30s-40s was tin whiskers. Think about how huge components and pitches were back then and they still noticed tin whiskers and changed the solder to avoid them.
I agree, and my belief is that RoHS is a convenient excuse for companies to continue creating e-waste, as long as it's "environmentally friendly" e-waste.
I suspect a similar story with "biodegradable" materials too, they just haven't become common enough to workd their way into products which people expect to last longer.
If I remember history, it was France who pushed for RoHS. Manufacturers wanted nothing to do with it precisely due to reliability issues. When the EU made it a requirement the entire world was forced to follow.
I remember having to retool most of my products at the time. It was nothing less than a nightmare.
Also the fact that some critical categories are exempt (military, aerospace, automotive, active implantable medical devices etc.) speaks volumes about that.
Just thought of this while reading your post: Could the tin whisker problem be solved by simply reflowing circuit boards every 5-10 years, before they actually short out? I mean, it's labour intensive but for specialized or hobby equipment, might be worth doing.
True. I wonder if you could do something with IR and a mask to selectively heat the bits of the board that’d take it?
Then again, later in the slides they talk about simply giving things a scrub with a wire brush to clean off the whiskers. Apparently they don’t regrow after the first few years.
> Could the tin whisker problem be solved by simply reflowing circuit boards every 5-10 years
Apart from logistics, many components have a hard time surviving the heat of soldering during original manufacture and may fail on subsequent reflowing.
Lead free solder typically has a melting point around 35C higher than tin-lead which exacerbates the problem.
Yes, lead-free solder brings a whole lot of trouble to the table. Perhaps someday someone will come up with a formula that doesn't -- but until then, I continue to use lead-based solder.
I have over a dozen instruments and several tools that are, in some cases, over 30 years old. I think all of my scopes, signal generators, DVM's, logic analyzers, DSO's, probes, lab power supplies, etc. are pre-RoHS and, in most cases, significantly so.
The transition to RoHS, while, in principle, well-intentioned, is likely to prove to have been a massive mistake.
Lead-free solder has one major problem: Tin whiskers.
One way to think about this is that all RoHS electronics has a stochastic failure rate. I have devoted more time than I care to admit studying tin whiskers in the context of my work in aerospace. I have, in that process, consulted with NASA scientists who were are the forefront of long term research on the subject. The most salient take-away was that we had no way to predict or truly mitigate tin whiskers. The only mitigation in aerospace is to, quite literally, send chips to services that remove all lead-free solder from the pins (or remove balls from BGA's) and replace them with conventional lead solder.
If this plays out as it could, landfills are going to be piled sky-high with broken electronics. From phones to laptops, TV's, ovens, clocks...anything really. And cars, yes, cars!
Lead-free RoHS solder is a ticking time bomb and, in my opinion, one of the most misplaced decisions made in the name of protecting the environment.
I have HP-41 calculators I bought in the early '80's that still work as new today. That's to say they are nearly 40 years old. There is no way a RoHS compliant calculator will survive 40 years. That is nearly impossible. And so, millions of them will end-up in landfills. Well done European Union, you really helped the planet with that one!
For those not familiar with RoHS issues (a deep and wide topic), here's a starting point:
https://nepp.nasa.gov/whisker/reference/tech_papers/2006-Lei...
This is very real.