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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 h
by robomartin 7y ago
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:
https://nepp.nasa.gov/whisker/reference/tech_papers/2006-Leidecker-Tin-Whisker-Failures.pdf https://nepp.nasa.gov/whisker/reference/tech_papers/2006-Lei...
This is very real.
- dredmorbius 7y agoTIL: RoHS == Reduction on Hazardous Substances. https://en.wikipedia.org/wiki/Restriction_of_Hazardous_Substances_Directive https://en.wikipedia.org/wiki/Restriction_of_Hazardous_Subst...
- hadlock 7y agoCongratulations you're part of today's 10,000. RoHS is required in most European markets and most electronic musical equipment since ~2005 is RoHS
- userbinator 7y agoI 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.
- squarefoot 7y agoAlso the fact that some critical categories are exempt (military, aerospace, automotive, active implantable medical devices etc.) speaks volumes about that.
- yencabulator 7y agoThe lead problem is with e-waste, basically manually disassembling/melting electronics for the parts, not while the device is in use.
- robomartin 7y agoIf 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.
- taneq 7y agoJust 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.
- marshray 7y agoMost complex boards will have a few parts (like plastic connectors) selectively soldered on after reflow.
- taneq 7y agoTrue. 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.
- crististm 7y agoTheoretically - yes. Practically - just imagine the logistics of that.
- johnr2 7y ago> 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.
- aij 7y agoI 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. Thanks for linking those slides.
- robomartin 7y agoNASA 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.
- blattimwind 7y agoThe 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.
- LorenPechtel 7y agoRepairing a satellite in flight is effectively impossible. Thus NASA cares far more about how long something will last than most users.
- deleted 7y ago[deleted]
- noonespecial 7y agoIn 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.
- robomartin 7y agoIf I remember correctly Swatch had horrible problems with tin whiskers. Here’s an interesting article from 2008. Among other things, it discusses the failure of a nuclear power plant due to tin whiskers. http://www.sigcon.com/Pubs/news/10_01.htm http://www.sigcon.com/Pubs/news/10_01.htm
- nrp 7y agoIdeally, 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).
- AstralStorm 7y agoFunny, 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.
- jacobush 7y agoWould that help against lead, or against tin whiskers? AFAIK tin whiskers can develop through lacquer too. But probably it helps some.
- johnr2 7y ago> 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.
- robomartin 7y agoSadly, 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.
- JohnFen 7y agoYes, 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.