81–90 of 133 posts
> No one has been able to eliminate whiskering, as the phenomenon is not yet fully understood. It's the kind of stuff we should be embarrassed not to understand. I get that understanding living things can be tricky due to complexity and issues with controlling conditions, but a lump of metal? Whatever we find out will at least save us money in damaged devices, and hopefully drive some progress in metallurgy as well.…
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I have dealt with the tin whisker problem in the context of aerospace applications (both space-borne and terrestrial flight), including extensive consulting with subject matter experts from NASA. The bottom line is quite simple: Tin whisker growth onset is a stochastic process. We cannot predict when it will start and we cannot prevent it. Once they start growing it is almost impossible to contain them. They will pok…
Are there any easy ways to clean up a PCB that's developed whiskers? And once a whisker erupts on a given PCB, does that generally indicate that others are likely to form on that board in short order?
Heat everything up in an oven, the solder will reflow, and you might temporarily fix the board. It’s a similar idea to the Towel/Xbox 360 fix. I can attest to having successfully saved lots of random electronics this way.
All of this started with the eco-friendly alternatives to lead solder, I have a lot of old computer hardware and motherboards, and the hardware from the early 2000s is the least reliable, whereas most game consoles, motherboards, etc. from the 80s and 90s works flawlessly. To this day I swear by the leaded stuff for personal use, it flows better, doesn’t crack, and is superior in every way.
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Does wisker form inside semiconductor also or do they use metals immune to that?
Yes they do but slower. In the past gold was used for wires from terminal to pads. Gold as far as i know is not so subceptible to form whiskers. But gold is expensive and now they use copper instead of gold.
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Consumer electronics used to break down all the time 50 years ago. Metal whiskers are not even close to being relevant when other factors impact reliability and durability to a far greater extent.
> Consumer electronics used to break down all the time 50 years ago But they could be easily repaired.
It really is an amazing phenomena. Effectively atoms of tin are moving from the tin out to the end of the whisker. We spent a week talking about whiskering(sp?) in my materials science class at USC because it was such a big deal in the EE world. Prior to that class my world view was that only electrons could travel through metal, only to find that metal can travel through metal too! Locally at NASA Ames they had an e…
> that metal can travel through metal too! I recommend watching clips of mercury amalgamations forming (nile red has some great videos on youtube). There is something about it that is both disturbing and beautiful to me.
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It is extremely unlikely to ever find any solution to the tin whiskers problem, other than alloying tin with toxic elements, i.e. either lead or antimony. The reliability problem could be solved only by replacing soldering with another method of making electrical connections during PCB assembly, e.g. thermal/ultrasonic welding of copper on copper, metal deposition in vacuum etc. While replacing soldering is possible,…
The reliability problem could be solved only by replacing soldering with another method of making electrical connections during PCB assembly, e.g. thermal/ultrasonic welding of copper on copper, metal deposition in vacuum etc. There's been some interest in laser welding for PCB assembly. But most modern components are not designed with the pins out where you can get at them with a laser beam. Laser welding is commonl…
Brazing is done at higher temperatures than soldering, but with a laser, you can apply the heat to just the area of interest, and hopefully not cook the ICs. Laser soldering already exists, and there are laser cutters, so adapting one for laser brazing ought to be possible.
The advantage of brazing is that you can use many more materials, most of which don't contain either tin or lead. Low-cost aluminum brazing rod or wire might work. Working temp around 700C. This is going to take careful heat management. Worth a try for aerospace applications.
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> It's the kind of stuff we should be embarrassed not to understand. We understand it. Onset is stochastic. Mitigation is impossible given current regulations in consumer-land. Read my longer comment for further details. EDIT: What I mean by "we understand it" is that we know that lead-free solder chemistry leads to tin whisker growth. When I was taking a deep dive into this many years back, the researchers I was wor…
That sounds like not understanding it.
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I wouldn't recommend this. If you do use lead soldering, make sure you don't breathe in any fumes.
The trick is not to end up inhaling or eating the solder in its solid state. This is actually quite difficult to avoid, as cleaning the tip of your iron will create lots of tiny solder balls that fly everywhere and can persist in your environment. Personally I would say that in hobbyist electronics tin whiskers are the least of your concerns when it comes to the reliability of the devices you’re making. I wouldn’t ri…
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No known cause or solution _yet_
It is extremely unlikely to ever find any solution to the tin whiskers problem, other than alloying tin with toxic elements, i.e. either lead or antimony. The reliability problem could be solved only by replacing soldering with another method of making electrical connections during PCB assembly, e.g. thermal/ultrasonic welding of copper on copper, metal deposition in vacuum etc. While replacing soldering is possible,…
The whiskers are not related to soldering. Of course there are some soldering issues which facilitate whiskers but that's about it. Tin is a normal plating material so you can find whiskets in places which were not soldered.
Accepting RoHS was in my opinion one of the most idiotic environmental initiatives that was rammed through without much thinking about long term cost / benefit analysis.