Electronics > Beginners
LED driver at -40degc ambient
mzzj:
--- Quote from: Ian.M on August 21, 2018, 02:33:08 pm ---
I don't have the data to asses the risk in relation to the risks of other possible low temperature and thermal cycling related failures. Maybe if you plow through the references from DBI corp's tinpest page, you'll have enough data, but its going to be highly dependent on the exact solder alloy used, and the the purity of tin plating on other parts of the device.
--- End quote ---
I don't have any probability numbers to throw either but given that we have had lead-free electronics for over 15 years without hearing of any case of tin pest affecting electronics in Lapland I'd say that it's not on top of the risk list.
I'm living in the coldest EU country, temperatures get below -40 in northern parts of Finland every year, yet I haven't heard of single case of tin pest actually affecting electronics.
Ian.M:
It can take a total of a couple of years below -10°C to initially trigger it, so summer temperatures are a key factor as if they reliably get above about 15° C, it will 'reset the clock' on it. That means its got a vanishingly small probability of occurring except in outdoor fixed installations in the high Arctic or above the snow-line, or installation in walk-in freezers etc. Any portable electronics or vehicle is likely to be brought into a shirt-sleeve environment at least annually.
If Treez is selling fixed exterior LED lamps to the Alaskan oil industry he probably should worry about it.
tooki:
--- Quote from: ArthurDent on August 20, 2018, 04:47:22 pm ---The question is will it work at -40 degf :-DD
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It's treez we're talking about. Make sure to suggest testing it at -40˚K, too! ;)
tooki:
--- Quote from: Ian.M on August 21, 2018, 03:39:40 pm ---It can take a total of a couple of years below -10°C to initially trigger it, so summer temperatures are a key factor as if they reliably get above about 15° C, it will 'reset the clock' on it. That means its got a vanishingly small probability of occurring except in outdoor fixed installations in the high Arctic or above the snow-line, or installation in walk-in freezers etc. Any portable electronics or vehicle is likely to be brought into a shirt-sleeve environment at least annually.
If Treez is selling fixed exterior LED lamps to the Alaskan oil industry he probably should worry about it.
--- End quote ---
Wouldn't one solution be to simply install small thermostatically controlled heaters into the units to always keep them above the critical temperature?
Ian.M:
Yep. However, running a heater 24/7 isn't going to do you any favours for energy efficiency, especially if your refrigeration plant has to get rid of the waste heat from the small heaters keeping the lights nice and toasty.
Also, this reasonably recent paper is scary:
https://www.emeraldinsight.com/doi/full/10.1108/SSMT-10-2013-0027
If their results are reproducible, it looks like the combination of low temperatures, the wrong solder alloy and mechanical stress can induce tin pest *WITHOUT* inoculation by grey tin dust in under a fortnight, which means a massive logistics problem maintaining heated storage so it isn't already compromised when you install it.
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