Stocking supplies: beginner ESD questions

Discussion in 'General Electronics Chat' started by ckk, Jun 4, 2014.

  1. ckk

    Thread Starter New Member

    Jun 2, 2014
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    Hi,

    I just got into electronics and I have begin stocking up on various supplies. I'd like to organize them in various types of boxes, and while I do have better picture of the issue after having read the Proper storage for Logic and other ESD sensitive IC's thread I still have some questions.

    This is mostly a question of practicality. Ideally, I'd like to by cheap, plastic storage bins for most of my stuff -- I do not yet have the space for a permanent work bench, so I need to be able to move things around easily. And my compontents should be safe, of course.

    Right away, all DIPs I have purchased so far are kept in cardboard boxes lined with conductive foam like these here (all pins are stuck in, so they are at the same potential). This works great for me: the 10cmx10cm boxes come fully assembled, are inexpensive, and they organize very well (I have ICs grouped by function, boxes labeled with part numbers, etc).

    Now, I also purchased quite a few other components, eg transistors and 2N7000 MOSFETs (thread). Keeping them in cardboard boxes is not practical. In a perfect world, I'd be able simply dump the stuff in clear plastic boxes like this or this.

    Question 1: Unless I'm mistaken, those plastic boxes linked above aren't ESD safe, which means I'd have to wrap components in aluminium foil or stick them in conductive bags, no? If I'm right, that would make things impractical, unfortunately, and I'd probably have to buy something like these conductive part boxes, but I can't find them cheaply here in Europe.

    Question 2
    : What other non-passive parts also susceptible to ESD? For example, I bought this kit of zeners + voltage regulators, and as you can see the storage box is non-conducting plastic. Are these parts at danger?

    I think that the way the major suppliers shipped me their parts, often with two kinds of ESD protection, has made me a bit paranoid :)

    Thanks in advance for your input!

    Christian
     
  2. #12

    Expert

    Nov 30, 2010
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    ..........
     
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  3. takao21203

    Distinguished Member

    Apr 28, 2012
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    Normal plastic is OK as long as it is not moved. It depends if static charges can build up.

    For instance when shipping a microcontroller or a memory IC, the envelope is moving a lot, so an antistatic bag must be used.

    I do keep some ICs in large black antistatic bags but others in plain plastic containers (not single chips).

    There was never a problem. Normally you don't have to be paranoid about static charges. Styrofoam and some kinds of foils are bad- you can notice they attract paper and hairs on the hand.

    It also depends on the carpet in the room.

    Normally if many components are in a box or in a bag they dont need protection- they are so many metal leads it all shorts out.

    Antistatic bags are a good investment however. Best is to leave components in their original packaging!

    And of course don't put sensitive chips in a plain plastic bag.

    But there is no need to use large antistatic ziplock bags for everything.
     
  4. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    Nothing is cheaper than aluminum foil, but it is a pain to use. Surplus stores use to ship chips stuck in sheets of styrofoam wrapped in aluminum foil (not recommended). I think the best protection for the money is sheets of 1/4" thick black conductive foam. You can see the markings, and I've never had a problem with them in standard clear plastic drawers.

    As for what to protect... Companies like HP demand that everything - including connectors - be handled with full ESD protocols. I think that's a bit extreme. Of course, anything silicon is at risk, and the risk increases in Winter, but there are levels. Generally speaking, bipolar parts are less delicate than FETs, FETs are less delicate than MOSFETs. Bipolar power transistors are hard to kill, but the biggest baddest power MOSFET has a gate that is less than 100 atoms thick.

    ak
     
  5. Wendy

    Moderator

    Mar 24, 2008
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    Black foam has a reputation for causing oxidation. Having said that, I do it myself.

    If you value your parts never store them in raw plastic. It is impossible not to have some movement, and as I said in my article, it doesn't take much.

    I wrote this article for the AAC ebook.

    ElectroStatic Discharge

    I would just line plastic shelves in foil and use that. If you can find conductive foam that is so much the better. But a properly grounded ESD Safe workstation is the best of all, along with static bags or tubes.
     
  6. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    I've noticed that, but I still think it is the best price/performance/hassle compromise. There seem to be two basic kinds of black foam. One is more dense, causes oxidation, and becomes crumbly after a few years. the other is less dense, more spongy, and doesn't fall apart with time. I've never had to buy this stuff so I can't recommend a vendor.

    ak
     
  7. ckk

    Thread Starter New Member

    Jun 2, 2014
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    Long term -- once I have the necessary space -- I'll probably settle for cabinets like this one. It seems like a nice permanent solution, and I'm ashamed to say that I'm just too lazy to line out everything manually.

    Short term: I found a cheap supplier of conductive boxes after all, eg this one (comes in different sizes). The box itself seems to come from one generic source but rebranded a few times, for example DigiKey has the exact same box (same part number) but under its own brand name (and much more expensive).

    That, together with all the other advice you gave me (that graphite spray one was simple and clever solution, but how well does it keep?), should cover it for a while now.

    Interesting note about the two types of different foam, becuase I use both of them (from different ESD boxes). I read about the oxidization issues but was under the impression that the quality had improved, I hope it's not just the foam type difference. The foam really is very practical, I'd like to stick with it.

    Thanks again, all, for the advice!
     
  8. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Just keep chips in their stick tubes? The stick tubes are PVC with no conductive effect, just plain plastic. That's how chips are shipped worldwide.

    PP (polypropylene) is also safe, that's used in clip seal bags and clear chinese food containers. You can get the pink PP bags labeled as static safe but it doesn't really matter, all clip seal bags are pretty good.
     
  9. ckk

    Thread Starter New Member

    Jun 2, 2014
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    Yeah, but those tubes don't organize well. That's why use these for chips. I take of the original label and stick it to the box, with multiple types per box (eg: timer box, logic gate box, ...).

    Uh, isn't regular (non-ESD) PP unsafe?
     
  10. #12

    Expert

    Nov 30, 2010
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    It makes an excellent insulator in polypropylene capacitors, so I'd think, "regular" polypropylene is a static electricity nightmare.
     
  11. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    It depends on the amount of chips you need to store! I forget people might think 50 chips is a "lot". Just cut the stick tubes with scissors to make little sticks, that's how I keep smaller quantities of things like PICs where I have lots of varieties of a few chips each. With the main PICs I use a lot I just buy by the stick and use a standard stick shipping box to hold all the sticks. You get a price break on stick quantities too.

    I don't believe so, and have used clear PP containers for 30 years to hold chips and semis etc, and have hundreds of these containers full of parts. I've never seen any evidence of static opening or touching them. However polyester clothing is a nightmare, I refuse to wear it and try to wear cotton only.


    I don't think it works like that? Chip tubes are PVC which is used as a capacitor dialectric, and I think the clipseal poly bags are PE which is also used in capacitors.

    Maybe the rules are different when the plastic totally surrounds the component?
     
  12. Wendy

    Moderator

    Mar 24, 2008
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    Not really, some plastics are mildly conductive, or are made so with additives. It doesn't take much for ESD control. Personally I would not trust pure polypropylene. I assume (and still do) that the plastic tubes for chips have the additive I mentioned.
     
  13. Treeman

    Member

    May 22, 2014
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    You cant get much more beginner than me.

    I keep my chips in the tubes stood up in a big see through yoghurt pot.

    All the projects are part sorted into clear ice cream tubs and stacked (except chips)
    All the rest is in any old box I could find. Cant buy the dividers - too normal!

    I'm paranoid too but figure not touching the chips till the last moment is the way to go. Lets hope theres no sell by date.:D
     
  14. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    I always assumed that too but have never been able to measure any conductance on a stick tube. Even with a meter that will read >50 megohms and the probes pressed hard on the tube a hair width apart.

    Normally static conductive plastic has a few meg per sq inch or so.
     
  15. ckk

    Thread Starter New Member

    Jun 2, 2014
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    Looking back, it looks as if this question fell through the cracks, so I'd like to ask again (somewhat extended): should I put the effort into ensuring proper ESD safety for regular diodes, zener diodes, transistors, and voltage regulators, or would that just be a nice-to-have?
     
  16. MrChips

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    Oct 2, 2009
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    I would apply the same ESD safeguards even though these are less vulnerable.
    Generally, I leave components in the same antistatic bags that they were shipped in.
     
  17. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Others may disagree but I would not bother. I have a number of assorted parts kits that came in PE or PP type compartment boxes.


    Probably 80% of the small parts I order come in standard PE clipseal bags or just PE bags with sticky tape.
     
  18. ckk

    Thread Starter New Member

    Jun 2, 2014
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    I found a solution I'm very happy with: conductive part boxes.

    First of all, they satisfy the most important requirement for me: they organize well. Some in this thread mentioned that they keep parts in the plastic anti-static bags they ship in, but I find those bags inconvenient: I need to keep them in boxes, finding the right bag is a pain, etc.

    These boxes come in two sizes, with various numbers of compartments (1, 2, 6, 12, 18). They stack well -- the lid contains grooves in which the top box can rest.

    They are also quite inexpensive: the 7” ones are under $5, the 11” ones under $11. Where I live, regular (non-conductive) PP boxes of the same size cost as least as much.

    Here are some resistance readings I took from: anti-static tubing, and anti-static bags, conductive foam, and the boxes, for comparison. There seems to be some variation in the conductivity, but my measurement technique was very crude, as you can probably tell.

    other-readings.jpg box-readings.jpg

    Regarding size, the 7” boxes should be sufficient for most types of parts. The next image shows the 18-compartment 7” box; the bottom left corner compartment contains exactly 50 BC547 transistors (TO-92).

    (Sorry for the crude labeling, I still need to print proper stickers.)

    7-inch-18-compartments.jpg

    These parts also fit the 18-compartment 7", but only barely, so I put them in a 12-compartment 7":
    7-inch-12-compartments.jpg

    For diodes, however, you'll need one of the 10” boxes (the 12-compartments are roomy, the 18-compartment ones are a bit tight):

    10-inch-12-compartments.jpg

    You can buy these boxes at all-spec (no affiliation). For Europeans it's a bit inconvenient as you have to use wire transfer (with fees, etc.), and shipping is expensive, too. But it's still far cheaper than the alternatives. For example, DigiKey sells some of those boxes, under their own brand, for $16.50, almost 4x as much.

    Thoughts?
     
    Last edited: Jun 27, 2014
  19. ckk

    Thread Starter New Member

    Jun 2, 2014
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    I finally printed labels for everything, so I wanted to share: here is my current parts collection (which will hopefully grow soon), safe & well organized.

    The "parts" section of my electronics cabinet:
    cabinet.jpg

    The conductive boxes really stack well. Very stable, no slippage:
    stack.jpg

    The contents of one of the boxes, including labels for each part:
    contents.jpg
     
  20. Wendy

    Moderator

    Mar 24, 2008
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    Zener diodes I would not worry about ESD at all. Transistor, low power diodes, and anything resembling an IC I would. The picture I showed on the ESD article I wrote was a regulator, and it was pretty blasted.

    I don't put a lot of effort at home into ESD control, and have paid the price in parts that were obviously walking wounded or out right bad. I don't think they left the factory that way, nor do I plan on changing my personal habits much.

    My point is ESD can bite you. It is important to know when you are screwing up.
     
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