Hello,
As many people have suggested to me, and probably others, to buy parts, especially capacitors, from reputable distributors, I now find myself with a bit of a problem.

Some parts I receive are in a moisture sensitive bag complete with a form on the back of the bag. The form says that if it's not filled out, there will be a label on some portion of the bag with info about the contents' moisture sensitivity. The problem is that some of these bags have neither their form filled out, nor an appropriate label attached.

Puzzled, I reached out to our anonymous distributor and was told that devices which are classified as <4 do not need the forms to be filled out. E.G. 2, 2a, 3, 3a, etc.

Now I can't seem to find the JEDEC J-STD-033 spec (for free), and what little I can find published on it I can't make sense of. It's like I have 2 out of 100 pieces of the puzzle.

Do they really not need a label if the moisture sensitivity is <4?
Can anyone comment on this matter, suggesting what should be done with the parts in these bags?

Thanks!

 

Are these for production, or just spare parts for you to have around? For production, absolutely follow all the specs, no one wants to recall and rework a large run of products. But if it's just for you to build stuff, I wouldn't worry too much about it. The parts are going to be exposed to the air anyway starting the second you open the package, and in my personal experience it's unlikely you'll have any problem with most parts that you assemble by hand even if they have been out in the air for months.

 

I intend to hand assemble the various parts/boards.

Obviously, I'd like to stick to manufacturer recommendations whenever reasonably possible because you never know when you'll suddenly have that one circuit that doesn't work because you ignored the manufacturer's instructions (costing you time and money.)

But though informative, that wasn't really the question. I was more asking about what would happen in a more ideal/manufacturer environment. Would blank forms on moisture sensitive bags be acceptable, or is anonymous company's customer support "pulling a fast one"? Is there a default set of recommendations to follow for unlabeled/unmarked bags of moisture sensitive parts?

Thanks again.

 

If you aren't willing to buy the standard that applies to handling moisture sensitive components, then don't be surprised that you can't find the information about what the standard is for handling moisture sensitive components.

There is no "default" recommendations for how to do things when you choose to not comply with the standards. It will depend on why you feel you don't need to comply with them (and there are lots of valid reasons to make that choice).

Many of the device handling procedures are in place to ensure adequate yield in automated manufacturing processes. When hand assembling components, the major variable is YOU, plus, you are in a position to be a lot more adaptable and flexible in responding to components that have been handled in such a way that they don't behave exactly the way an automatic process needs them to behave.

 

Mr. WBahn, I suspect that you read through my post a bit too fast and so came to some unexpected conclusions. I'm not condemning you here, just trying to sort things out before they get out of hand.

If you aren't willing to buy the standard that applies to handling moisture sensitive components, then don't be surprised that you can't find the information about what the standard is for handling moisture sensitive components.

Umm, maybe you don't know this but many programmers program their computers without ever having a copy of IEEE 754. That is to say, we have no idea how floating point numbers are supposed to behave according to the official standard. And most high level languages use floating point numbers by default or as their only option.

Yet, the code utilizing floating point numbers works. By the same token, just because I don't own a standard, doesn't mean that the methods/procedures that I use have to fail. I expected, much like with floating point, to be able to find some degree of information talking about how to handle moisture sensitive parts without having to purchase the standard.

There is no "default" recommendations for how to do things when you choose to not comply with the standards.

It will depend on why you feel you don't need to comply with them (and there are lots of valid reasons to make that choice).

I never "choose to not comply with the standards." I never even said that above. What I asked was, "Is there a default set of recommendations to follow for unlabeled/unmarked bags of moisture sensitive parts?" As in, these bags are unlabeled/unmarked, does the standard or other industry best practices describe what to do in this case?

To be fair, you might have implied that by noting that I don't own a copy of the JEDEC J-STD-033 standard (and won't be purchasing one), but that was not my intention. Being a student and being intentionally ignorant are two different things.

Many of the device handling procedures are in place to ensure adequate yield in automated manufacturing processes. When hand assembling components, the major variable is YOU, plus, you are in a position to be a lot more adaptable and flexible in responding to components that have been handled in such a way that they don't behave exactly the way an automatic process needs them to behave.

A good point.

Thanks

 

I regularly install components that have sat in drawers, unprotected for years or decades. I cannot think of any instance when such a component was DOA. When I have a component failure it is inevitably due a mistake like powering the board with the wrong voltage or polarity or shorting something while troubleshooting. Electronic components are far more robust than you seem to think.

I suspect that the seller in your case put these components in the moisture resistant bags even though it was not required.

 

I regularly install components that have sat in drawers, unprotected for years or decades. I cannot think of any instance when such a component was DOA. When I have a component failure it is inevitably due a mistake like powering the board with the wrong voltage or polarity or shorting something while troubleshooting. Electronic components are far more robust than you seem to think.

I suspect that the seller in your case put these components in the moisture resistant bags even though it was not required.

I live in SE Asia, parts rot away before my very eyes.

What I mean by that is that they become un-solderable due to corrosion of the lead materials in less than a year.
In high humidity situations, it matters.

 

I live in SE Asia, parts rot away before my very eyes.

What I mean by that is that they become un-solderable due to corrosion of the lead materials in less than a year.
In high humidity situations, it matters.

Okay, that makes more sense. But if that is what you are worried about, simple inspection will detect them. If you get corroded parts, ask for a refund.

 

The moisture sensitivity labels MSL are there mostly to avoid popcorning of the components in the reflow oven. When I worked in an assembly plant, devices which had a high MSL and were suspect of improper storage, would be baked in a temperature chamber at 105C for 48 hours and that would slowly remove any absorbed humidity.

Popcorning is exactly what it seems: moisture absorbed and trapped inside a component, would become high pressure steam and without the means to release it in a controlled fashion, would cause the package to explode like a popcorn kernel.
If you are going to soldering it by hand, there is usually no problem if done slowly one terminal at the time.
Of course, if the terminals have oxidation, that is a completely different problem.

 

Shipping and delivery of electronics components from the manufacturer to the consumer must adhere to specific standards.
Protection against ESD and high humidity would be at the top of the list.

The problem with high humidity only affects long term storage. If the parts are in good condition and will be used within the near future, I would not be so concerned.

It becomes an issue when components are to be stored beyond a few months. This is when the components need to be stored in low humidity environments (e.g. seal containers with silica gel packets.)

I receive shipments with silica gel packets and moisture indicator cards. I routinely save the packets and cards and rejuvenate them at low temperatures in the oven. Note that some packets are made of plastic and will melt if the temperature is set too high.

 

Mostly the damaging effect of humidity on electronic components is to the solderability. Automated assembly equipment, as well as soldering, either reflow or wave, lacks the ability to compensate for poor solderability. But a human with good vision, adequate lighting, and good soldering skills can usually compensate for that surface damage that would prevent a good automated solder connection. It might even take a bit of solder flux to make it easy to get a good connection. And poor solder connections are certainly a frequent cause of product failure.

 

I live in SE Asia, parts rot away before my very eyes.

What I mean by that is that they become un-solderable due to corrosion of the lead materials in less than a year.
In high humidity situations, it matters.

This is interesting. I'm also in a very humid climate (S. Florida), it's not unusual to have 90% humidity here. But storage is almost always indoors where air conditioning keeps the humidity much lower. Is it different where you are?

 

Thanks everyone. None of you really answered the original questions, but enough personal experience and professional experience stories have been provided so that I have a good idea of what to expect and what to do.