Curiosity "Yea or ney, baking or drying chips before soldering" - Page 1
Forum section: electronics / beginners

author: pcprogrammer
author_rank: Super Contributor
timestamp: December 18, 2024, 08:04:19 am
content: In this posthereit is mentioned that a problem I had with a chip could be caused by steam cracking something inside the chip.I have read threads about it here on the forum, like this onehttps://www.eevblog.com/forum/chat/dehydrating-moisture-sensitive-chips-at-home/and it is a bit inconclusive.When is it needed, if ever, for a hobbyist to dry his chips before soldering them to a board.Does it apply for all chips, or only the ones that need to be soldered with hot air, like BGA and QFN.Going on advice of a friend of mine who has worked in the field of electronics for many years, I did not do it with the third chip I got for the board mentioned in the above referred thread, and it seems to work, at least the memory is stable.So what is the case here.

author: Berni
author_rank: Super Contributor
timestamp: December 18, 2024, 08:47:05 am
content: In the majority of cases it does not matter.If you live in a particularly high humidity area and are having problems with chips during reflow soldering then you certainly should bake them.But in most other cases it doesn't matter as much. What tends to be more of a problem with long term stored components is the pins oxidizing and then not soldering very well (especially if the solder paste is getting old and the flux in it is not quite what it used to be anymore)

author: RoGeorge
author_rank: Super Contributor
timestamp: December 18, 2024, 09:16:27 am
content: Never pre-baked any components, never had a cracked chip ever (along decades of electronic tinkering).Living around 45th parallel north, continental climate, with normal humidity levels. Always manual soldering/desoldering (only did reflow soldering/desoldering a couple of times). I do have a hot air soldering station, too, but never use it, not even for desoldering (to desolder, I use solid copper wire formed in the shape of the IC footprint instead of hot air, or a siringe nail if it's a THT IC).This doesn't mean one should disregard manufacturer's advice.

author: Whales
author_rank: Super Contributor
timestamp: December 18, 2024, 09:52:53 am
content: I've definitely had issues with surface corrosion on QFNs, but have not observed obvious component failures caused by steam during soldering.I've read that baking FR2 PCBs might reduce blistering during soldering, can anyone confirm that one?

author: AndyC_772
author_rank: Super Contributor
timestamp: December 18, 2024, 10:06:53 am
content: Moisture absorption is absolutely 100% a real thing and a real problem.The problem comes when trapped moisture turns to steam inside the package. Chips that are soldered by hand are less likely to have an issue, because it's only the pins which really get hot during soldering. Hot air or IR soldering heats the entire package well above the boiling point of water, and so can produce high pressure steam inside the package.The physically bigger the package, the more moisture can be trapped. Small chips are generally less susceptible.Some years ago the company I was working for manufactured a batch of boards using a Freescale PowerQUICC processor, which came in a BGA package around 30mm square. The package was composed of a very thin PCB with the balls on the underside and the die itself, enclosed in epoxy, on the top. It's a prime candidate to be affected by moisture absorption.The batch had a very high failure rate. When we x-rayed the boards, it was clear that the CPUs had 'popcorned' - the interposer PCB part of the package had bulged out, which resulted in multiple solder bridges in the centre, and very thin, stretched out joints around the outer edge. The effect was dramatic and, of course, we had to rework every board. A costly learning exercise.

author: Siwastaja
author_rank: Super Contributor
timestamp: December 18, 2024, 10:13:49 am
content: I think the list of choices is weird, conflating the decision with package types etc. irrelevant details while ignoring the possibility that someone might RTFM. Hence, to me, more obvious set of choices would be:(1) I follow manufacturer instructions to the letter every single time(2) I try to at least roughly follow the guidelines whenever possible(3) I completely ignore the guidelinesFrom this set, I would choose (2) for hobby projects and prototypes.The initial list of choices is weird because it lacks all the correct decision criteria for baking, which is whether the parts have been out of sealed moisture barrier packs or not, and for how long, and what is their MSL. And that matters. Some LEDs are MSL4 and pretty sensitive to moisture. If you take them off the bag, indicator shows they are good, and use within a few days, of course you won't bake them. And if they sit for half a year on your table then you can expect a lot of failures if you don't bake them.And, as usual, I don't make a big difference between hobbyist vs. professional: in both cases the main goal is to build a thing which works (at all, and reliably). And in both cases following instructions is the best way to savetime. For hobbyist, time is valuable as it can be spent in enjoying working with the thing instead of doing tedious repair. For professional, time is simply money (and delay in time-to-market can be very costly). But the end result is the same: being careful, avoiding assumptions, reading instructions pays off.

author: pcprogrammer
author_rank: Super Contributor
timestamp: December 18, 2024, 10:59:51 am
content: I added the options Siwastaja mentioned, so now he can make his vote too.Quote from: Siwastaja on December 18, 2024, 10:13:49 amI myself have never noticed advice about moisture levels, but that only might show to what level I read the datasheets.Quote from: Siwastaja on December 18, 2024, 10:13:49 amSure as a hobbyist it is always nice if things work of the bat, but when it does not I try to see it as a learning experience.But chucking up some failure to "is caused by steam while soldering" without any proper investigation is in my eyes short sighted.AndyC_772 his post provides some good information and shows that they found the problem to indeed be moisture. But that is with a large BGA package, and that is why I added the options that one only does it for specific type of parts.Next time, when I'm up to something new, I will read the information provided by the manufacturer more thoroughly.

author: xvr
author_rank: Frequent Contributor
timestamp: December 18, 2024, 12:57:17 pm
content: First of all there is a standard for handling, packing, shipping and use of Moisture, Reflow and Process sensitive devices - IPC/JEDEC J-STD-033It defines 6 level of MSL. Level1 do not required any special handling or any baking. Level 6 required always (even when chip is right from transportation box)Also it states that hand soldering DO NOT REQUIRED any baking, for any MSL.https://www.ti.com/lit/an/spraby1a/spraby1a.pdf

author: Siwastaja
author_rank: Super Contributor
timestamp: December 18, 2024, 01:07:48 pm
content: Quote from: pcprogrammer on December 18, 2024, 10:59:51 amOh nice, much appreciatedQuoteGood news: distributors print it in big letters in packaging! Furthermore, they put indicator sheets inside the bags, which exactly say what to do, like: "MSL 3 or higher: bake parts if this thing is NOT pink..."So no need to dive deep into documentation. They do this because contract manufacturers etc. have no time or resources reading datasheets (which are for designers). Of course as a hobbyist, you are both designer and manufacturer at the same time.QuoteHobbyists who are learning face problem after problem in any case. That is the definition of learning. Like, you learn that a too high resistor value for pull-up causes slow rise time in I2C, by looking at oscilloscope while wondering "why this does not work". But ESD and moisture damage is really sneaky; they can causeanysort of malfunction, a subtle or dramatic one, and do it with a delay. And it leaves no hints behind; say, those can shift your regulator voltage, make your LED blink, ... which drives the poor hobbyist to debug around their code, solder joints, capacitor values etc. whatever.The life of a hobbyist is most rewarding and fun when they can concentrate on making and correcting mistakes intheir design, not chasing ghosts where the final solution after 10 hours of debugging is to desolder and swap a part and "oh, now it works". That is pretty frustrating and results in no learning at all.

author: Siwastaja
author_rank: Super Contributor
timestamp: December 18, 2024, 01:14:39 pm
content: Quote from: xvr on December 18, 2024, 12:57:17 pmA reference would be nice for us who don't have the standard.Even though damage from hand soldering is much more unlikely (to the point of not worrying about it too much), I have had some WE RGB LEDs fail even when hand-soldered; the kind of thick, formed-into-package leads engineered to conduct heat away from the emitter effectively, and as flip-side, carry heat into the emitter while soldering. Turned out the first batches (in reflow) were OK, but after more boards produced some months later they showed >50% failure rate in reflow, and when replaced with hand-soldering even some % of those failed, and replaced again with more careful (as quick as possible) hand soldering, which turned out fine. For the next batch I baked the remaining LEDs and those were OK.And IIRC those LEDs were not even MSL4, but just MSL3. I think people have had pretty large scale moisture problems with WS2812 and similar, you can find threads about it here and elsewhere.After the LED experience I have started taking the moisture sensitivity ratings more seriously, especially during summer when RH routinely is > 50% and sometimes over >70% for weeks. In winter with -10degC outside and thus 10-20% RH indoors I'm more worried about ESD than MSL.Probably easier than baking is to order just what is needed and new parts every time you get a project from a hold; I mean you usually have to buysomenew parts anyway so you get them in the same shipment, and extra cost of ordering just the amount needed instead of double is not that high.

author: wraper
author_rank: Unknown
timestamp: December 18, 2024, 01:21:30 pm
content: You certainly should bake BGA with fiberglass substrate and LED with high MSL if they were not stored properly in moisture barrier bag. Other than that, usually you can get away with no baking.

author: pcprogrammer
author_rank: Super Contributor
timestamp: December 18, 2024, 01:35:26 pm
content: QuoteWhen you order from Aliexpress this is almost never the case.The F1C100s and F1C200s chips I ordered arrived in their reel tape package placed in a plastic zip lock bag and that is it.You can count your blessings if the keep the parts in the reel tape. Have received sop-16 chips that had no protection at all and 10 of them were stuffed in a zip lock back resulting in some pin bending of course.Sure is my own fault for not ordering from reputable firms, but hey, I'm a cheap skate.

author: CaptDon
author_rank: Super Contributor
timestamp: December 18, 2024, 01:41:42 pm
content: Our contract manufacturer was required to follow manufacturer guidelines and if any doubt bake them anyway. Our CM made many different products for us and there was always excess stock that may sit on shelves for a year or more until we made the next round of boards. Yes, we had troubles related to moisture, often from tarnished silver plated leads that didn't make a proper solder bond. We also had severe problems with some six and eight lead PV devices. They were the size of a 555 in a white plastic or epoxy package. They were notorious for moisture absorbsion that caused a lower voltage output. We used them to drive power MOSFET's in some simple high current on/off circuits (locomotive ditch lights). With insufficient gate voltage the MOSFETS went linear and burned up including burning holes in the board they were attached to.

author: xvr
author_rank: Frequent Contributor
timestamp: December 18, 2024, 01:46:32 pm
content: Quotehttps://www.jedec.org/system/files/docs/J-STD-033D.PDFPage 9:Quote

author: u666sa
author_rank: Frequent Contributor
timestamp: December 18, 2024, 01:48:20 pm
content: This is along the lines of drying drowned phones in rice. Also, drying them in microwave.

author: wraper
author_rank: Unknown
timestamp: December 18, 2024, 05:22:56 pm
content: Quote from: u666sa on December 18, 2024, 01:48:20 pmAnd then laptop and GPU repairers wonder why BGA chips popcorn during reflow, blame lead-free, waste time and effort on reballing chips they bought with tin-lead solder balls. While all they need to do is baking them and storing in moisture barrier bags with desiccant. And frankly you should bake PCBs which are to be repaired as well as it reduces chance of popcorning to zero even if overheated during reflow.

author: Zoli
author_rank: Frequent Contributor
timestamp: December 18, 2024, 06:34:36 pm
content: To chime in my experience: SOP-8-EP, MSL-3, received from LCSC already compromised. If I'm heating the pad, the IC blows up on power, if I solder only the pins, it happily works.

author: golden_labels
author_rank: Super Contributor
timestamp: December 18, 2024, 09:10:49 pm
content: Asking people, what is their experience with following (or not) such guidelines, is not going to yield too much useful knowledge. Failure due to moisture is a low probability event. So the expected replies are that nobody ever experienced that or noise-level positive responses, regardless of what the truth is. The events are also not independent.Where it matters is a production line. Tens of thousands, tens of millions items produced, coupled with potential liability for parties involved. In this context, yes: moisture trapped in a packaging may cause damage during rapid heating in the soldering process.Is it a problem in hobbyist or small volume use? Show me people who follow the prescribed temperature curve during soldering, or who don’t occassionally overheat components. Damage caused by either of those will occur much more often than from moisture.As a hobbyist I never followed the moisture guidelines. But I would, if I had the ability to do that without much hassle.

author: wraper
author_rank: Unknown
timestamp: December 18, 2024, 09:33:21 pm
content: Quote from: golden_labels on December 18, 2024, 09:10:49 pmNope, it's not a low probability event if parts are moisture sensitive. Usual resistors, MLCC, and most of plastic packages are either not sensitive or are barely sensitive. If sensitive parts stayed in open air for a few years, you may easily get 100 of 100 of large BGA popcorn during reflow or something like 1/4 of LEDs dead right away or experiencing a extremely high mortality in first days of use.

author: wraper
author_rank: Unknown
timestamp: December 18, 2024, 09:55:25 pm
content: For example popular WS2812B are notorious for people complaining about high failure rate. Example:https://www.eevblog.com/forum/projects/would-you-use-ws2812-(and-friends)-inside-a-product/msg972508/#msg972508However nobody or barely anyone who I have seen complaining about them bothered to figure out they're MSLLEVEL 6.Quote

author: pcprogrammer
author_rank: Super Contributor
timestamp: December 19, 2024, 06:30:34 am
content: Quote from: wraper on December 18, 2024, 09:33:21 pmHere you mention large BGA being subject to this moisture problem, but I doubt many hobbyist will be soldering large BGA's, or small ones for that matter. I myself stay clear of them for sure, because I don't have the equipment for them. And based on my experience with QFN I rather not use those packages either. Small pins I can still deal with.The fact that some LED's are also prone to having problems with moisture is more likely to be a problem for a hobbyist.

author: wraper
author_rank: Unknown
timestamp: December 19, 2024, 06:42:29 am
content: Quote from: pcprogrammer on December 19, 2024, 06:30:34 amAFAIK virtually all SMT LEDs are moisture sensitive. However some are MSL 2 which is of little concern but others a whopping MSL 6, most of simple LEDs seem to be MSL 3.

author: Siwastaja
author_rank: Super Contributor
timestamp: December 19, 2024, 07:17:31 am
content: Quote from: golden_labels on December 18, 2024, 09:10:49 pmThis part is true, otherwise your reply is a bit misleading. It's a low probability event only in the sense that if you count every component in existence and randomize their storage conditions and solder them all, maybe just 0.001% fails. But this does not ease your pain when your failure rate is 100% and you are failing again, again and again, simply because you happen to have type of parts thataresensitive (unlike "average" part, a meaningless concept). For example: some LEDs as mentioned.

author: Smokey
author_rank: Super Contributor
timestamp: December 19, 2024, 08:47:12 am
content: The addressable LEDs like WS2812 are really bad when it comes to moisture.I let my CM decide if they need to bake anything in production.While we are on the subject, I wish Digikey would provide an option for small prototype quantity orders like "Don't include the desiccant and indicator card in this order". I always feel bad ordering like 10 LEDs and immediately throwing away the silica bag and indicator they include in there. It would save everyone a little money/time/effort/waste.