Freezing ICs -- what are the caveats? - Page 1
Forum section: electronics / beginners

author: fzabkar
author_rank: Super Contributor
timestamp: July 31, 2020, 09:48:30 pm
content: BGA ICs can be cracked by "popcorning". That's when trapped water expands too rapidly. But what happens if this trapped water is rapidly frozen? Does the ice crack the package?How does one explain specs like this?https://www.intel.com/content/dam/www/public/us/en/documents/product-specifications/ssd-dc-s3500-m2-spec.pdfQuote

author: ogden
author_rank: Super Contributor
timestamp: July 31, 2020, 10:09:03 pm
content: Temperature grades (consumer/industrial/automotive) are not about freezing of trapped water.https://en.wikipedia.org/wiki/Operating_temperature

author: thm_w
author_rank: Super Contributor
timestamp: July 31, 2020, 10:43:38 pm
content: So the issue with water being heated is that it turns into steam:- The volume change from water to steam is 1,700x- The volume change of water to ice is 1.09xSo.. most likely that 9% volume difference is not enough to cause any damage.Good question though. Maybe there are some niche chips that don't like this, but most will be fine.

author: fzabkar
author_rank: Super Contributor
timestamp: July 31, 2020, 10:45:40 pm
content: Quote from: ogden on July 31, 2020, 10:09:03 pmAre we to understand that the manufacturer's specification is written with the assumption that the device has no trapped water? Does this then mean that, if the device is subject to popcorning if and when it absorbs water, then it will necessarily be subject to cracking when that same water is subjected to 0C and below, regardless of the non-operating spec?This then begs the question, can any device be free of trapped water under normal usage in normal environments? If not, then the manufacturer's spec is meaningless, is it not?

author: fzabkar
author_rank: Super Contributor
timestamp: July 31, 2020, 10:47:56 pm
content: Quote from: thm_w on July 31, 2020, 10:43:38 pmIce can crack rocks.

author: thm_w
author_rank: Super Contributor
timestamp: July 31, 2020, 11:16:16 pm
content: Quote from: fzabkar on July 31, 2020, 10:47:56 pmSure, but how much water is present in those rocks, and in what concentrations?Is rock the same material as epoxy resin to encapsulate the IC?https://www.aps-prg.com/baking-and-dry-packing/http://www.aecouncil.com/Papers/aec8.pdfhttps://www.intel.com/content/dam/www/programmable/us/en/pdfs/literature/an/an113.pdf

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: August 01, 2020, 04:27:39 am
content: Quote from: fzabkar on July 31, 2020, 10:45:40 pmNo, we are not to understand that. Everybody who deals with these devices should know that there is a VERY tiny amount of water vapour in the cavity and within the plastic packaging of each device if it has been exposed to the atmosphere for even a few hours. In that case it must be assumed that humidity has leaked into it and it cannot be run through a solder reflow oven before baking it for a while to drive out the now-present humidity within. Failing to bake it (usually at somewhere around 40 to 125 deg C for a few hours to a few days) will subject it to the "pop-corning" you speak of. If it comes from the manufacturer in a sealed humidity-free package then it has already been baked and can be subjected to the assembly and solder reflow process straight away.Once the device has been assembled and cooled then it is subject to ingress of said humidity once more but by then it doesn't matter.Quote from: fzabkar on July 31, 2020, 10:45:40 pmNope. The same water vapour talked about above is a VERY small amount so cooling it to below freezing will cause it to settle on all surfaces within the package and crystallize, yes, but there is much more room than the volume of the water itself, under the hood there for it to exist. Furthermore the expansion of the now-frozen water, 9% or so as thm_w says still does not nearly use up enough space within the package to create any risk of breakage.Quote from: fzabkar on July 31, 2020, 10:45:40 pmNope again. The device, in normal usage can never be absolutely free of water vapour inside the package. Even if it can operate at above 125 deg C or below 0 deg C, there will still be some residual vapour there that is not driven out by heat or completely crystallized on a surface. It is just not dangerous so no one worries about it after assembly.

author: magic
author_rank: Super Contributor
timestamp: August 01, 2020, 08:00:04 am
content: Quote from: fzabkar on July 31, 2020, 10:45:40 pmWe are to understand that nonsensopedia is rarely a helpful source of informationStorage temperatuere- the temperature at which the device can safely be stored. If the SSD is rated down to -50°C, it will not crack apart at -50°C, unless you fill the case with water. All sorts of plastic items are regularly taken to sub-0°C temperatures and they survive just fine.Operating temperatuere- the temperature at which the device is guaranteed to operate correctly. There are various reasons why a 0°C rated device may fail to operate at -50°C, such as: higher threshold voltage of FETs, lower beta in BJTs, excessive thermal drift of analog characteristics like offset voltage of ampliifers, probably many others. If Intel used some 0°C rated components in the SSD, this is the most likely reason why the whole SSD is rated only for 0°C.And I have no idea how flash memories themselves are affected by temperature, but I'm quite sure that they must be, one way or another.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 01, 2020, 09:10:20 am
content: It seems you are operating under an assumption that moisture in ICs freezing would likely/possibly cause damage to the parts, andthiswould be the reason why some parts and devices are rated to be only used above zero deg C.This assumption incorrect. I'm not saying it's completely impossible, but I have never heard about moisture freezing cracking components, analogous to steam cracking them in rapid heating. The reason is given above:Quote from: thm_w on July 31, 2020, 10:43:38 pmThe reasons why some parts and devices are rated for 0 degC minimum operation are all completely elsewhere, and do not relate to the phase changes of water - 0 degC just happens to be a convenient round number when you have to specifysomething(say, your engineering says they are certain the component can handle -7 degC fine, then you don't rate it for -7, but 0 instead).Magic listed many examples already: most analog circuits are very temperature sensitive, their "unwanted" side properties, or even the main parameters they operate upon change radically. Sometimes compensation schemes are added but even they have some range to operate over.For example, many older car radios start to soundreallydistorted when it's very cold (like -30degC) outside. Obviously, their AB output stage transistors fall too far out of bias, with a lot of crossover distortion ensuing.Another thing I could add over magic's list, is that li-ion cells can't be charged at all, or must be charged at reduced rate at low temperature, because chemical reactions are more sluggish, and lithium ion intercalation in the graphite lattice would fail, causing dangerous lithium metal plating instead. Again, typically specified as "charging forbidden below 0 degC", but in reality, have nothing to do with water, and 0 degC is just an arbitrarily chosen value which is misleading because it also happens to be the freeing point of water.

author: atmfjstc
author_rank: Regular Contributor
timestamp: August 01, 2020, 11:27:16 am
content: I've tried to parse the OP's question and have to confess I don't see why there should be anything unusual about the SSD being rated for a storage temperature of "-55 to 95C", nor why this would suggest that anything could happen to ICs and any water molecules therein as they go down in temperature.As far as I know, -55C is the lowest temperature in the widely accepted storage/operating temperature grading system. The device being rated for -55C doesn't mean that it will break below that, just that the manufacturer is willing to vouch that it won't break before that temperature. For all we know, the device might well survive being brought down to near absolute zero, as long as you don't power it.

author: Siwastaja
author_rank: Super Contributor
timestamp: August 01, 2020, 12:03:24 pm
content: Obviously, testing and guaranteeing things most customers do not need or want is only an added cost and added risk for the manufacturer.Sometimes, they can also sell wider operating ranges for premium price; in this case, it would be a bad business idea to specify the cheap version equally well, even if it could technically perform the same.

author: TimFox
author_rank: Super Contributor
timestamp: August 01, 2020, 01:23:14 pm
content: Decades ago, in the early years of MRI, an important engineer at GE reported on experiments with operating semiconductors at liquid nitrogen temperature (78 K). The ON resistance of power MOSFETs was greatly improved, but plastic packages did not survive the temperature extreme.

author: magic
author_rank: Super Contributor
timestamp: August 01, 2020, 02:00:50 pm
content: Yeah, that's a bit extreme. But if you look around, the cheapest jellybean chips like LM258 are available rated not only to survive but also to operate at -40°C, in all kinds of plastic packages, even BGA.Lots of electronics operate outdoors and are just fine - automotive ECUs, CCTV, cellphones, ...

author: David Hess
author_rank: Super Contributor
timestamp: August 01, 2020, 04:08:51 pm
content: As part of testing for operation over the military temperature range, we used an environmental chamber cooled by liquid nitrogen. We did not need liquid nitrogen temperatures but it was the most economical cooling option down to -55C or whatever we needed.But when I did destructive testing to see what failed first at cold temperatures, I went all the way down to liquid nitrogen temperatures. I do not know about CMOS since these were all linear bipolar designs but nothing failed down to −320F. This included plastic packaged ICs, solid tantalum capacitors, ceramic capacitors, resistors, glass encapsulated diodes, etc. We deliberately avoided aluminum electrolytic capacitors since we already knew that they do not work well when frozen. Extended operation at that temperature would have required a solder without tin.Quote from: fzabkar on July 31, 2020, 10:45:40 pmThe specifications for assembly assume that the parts have been property stored, or conditioned, to remove absorbed water before soldering. Usually this means the parts are removed from the manufacturer's packaging shortly before assembly.

author: tszaboo
author_rank: Super Contributor
timestamp: August 01, 2020, 04:15:05 pm
content: The temperature range has nothing to do with ice or steam. That is a commercial grade device, so the components are rated for 0 to 70. If it would be industrial, then it would be -40 to 85. For opamps and such, they might even do grading, based on offset voltages for example. For a purely digital device, it has nothing to do with it. It is just not rated for it, because it is not an expected usage of the device.

author: KaneTW
author_rank: Frequent Contributor
timestamp: August 01, 2020, 04:24:20 pm
content: CPUs work with liquid nitrogen cooling. When people do extreme overclocking, the CPU gets really, really cold at times. So the stated operating range doesn't have that much to do with reality.