ESD safe storage considerations - Page 1
Forum section: electronics / beginners

author: Lomax
author_rank: Frequent Contributor
timestamp: March 31, 2016, 02:28:19 pm
content: I've reached a point in my accumulation of components where I should probably be looking at moving all ESD sensitive components into protective storage bins. While I mostly have TTL jellybeans, BJTs and plain-jane diodes, more and more highly sensitive (and sometimes expensive) parts such as MOSFETs and MCUs are finding their way into my bins. The risk of damaging parts, as well as my wallet, is only going up. The fact that the polypropylene bins I currently use build up a static charge as soon as you look at them only adds to my concerns. I'm a little confused though; ESD safe part bins are made from a conductive plastic - does that mean I should be grounding them? If so, doesn't that pose a risk wrt high-voltage & lightning strikes? I've tried searching here and on the web but haven't been able to find any definitive answers...

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: March 31, 2016, 02:37:53 pm
content: Supposed to be soft-grounded via 1meg resistance to ground.

author: rdl
author_rank: Super Contributor
timestamp: March 31, 2016, 05:15:29 pm
content: If you're buying parts from a reputable distributor, just leave them in whatever packaging they are shipped in and store them in boxes. I use shoebox size plastic containers with latch on lids.

author: mazurov
author_rank: Frequent Contributor
timestamp: March 31, 2016, 05:33:46 pm
content: You can use aluminum cooking foil - wrap it around your precious part making sure all pins are shorted together. For TO220-sized ones you can short the pins with a piece of bare copper wire. Small tin cans (Altoids) work well too.The same works when you mount the part - keep pins shorted until the circuit is complete. When I was a kid I have dual gate MOSFETs in small metal package that were absolutely unworkable. The trick was to make a small ball out of the foil and wedge it between the pins close to the package. The hardest part was not to forget to remove it prior to smoke test.

author: mmagin
author_rank: Frequent Contributor
timestamp: March 31, 2016, 07:38:54 pm
content: I use a couple of these for stuff I don't want to just leave in a messy collection of antistatic bags in a cardboard box:http://www.mcmaster.com/#4845t53/=11s5cusAt the time, everything else I could find was either more expensive or just conductive-treated cardboard, not actual plastic.Mind you, this isn't single-part number per drawer. E.g. all the non-rf mosfets are in about 3 drawers: small stuff (2n7000, etc), big stuff Vds <100V, big stuff Vds >=100V.I still tend to leave SMT stuff I won't be using for prototyping in bags in boxes if it's just there for a future project I need to design a board for.

author: dadler
author_rank: Unknown
timestamp: March 31, 2016, 07:53:44 pm
content: I leave all of my mosfets etc in the dissipative bags/cut tape strips/tubes that they come in from Mouser and Digikey. I only remove them to solder them to a board (or breadboard with them, after which I either put them back or put them in one of those small ESD dissipative snap boxes, e.g.http://www.amazon.com/WenTai-Anti-Static-Component-Small-Part-Organizer/dp/B00JZ3NFO6).

author: mmagin
author_rank: Frequent Contributor
timestamp: March 31, 2016, 08:05:21 pm
content: Quote from: dadler on March 31, 2016, 07:53:44 pmI don't actually trust those black WenTai boxes to be antistatic. I have a small bit of them from Adafruit. At least with my improvised electrodes (strips of foil and some kind of pressure on the assemblage) I haven't been able to see any lower resistance across them than their other colors of boxes. What made me suspicious is that don't actually say anything about antistatic on the plastic itself, and compared to antistatic plastic I've seen, it's much too shiny -- I think the usual stuff is carbon filled and thus has kind of a dull appearance.I first tried with my cheesy ebay surface resistance meter, then I tried again with my antique Fluke differential voltmeter (which can measure up to 250G ohm), results weren't convincing.

author: dadler
author_rank: Unknown
timestamp: March 31, 2016, 08:19:55 pm
content: I actually got mine from Adafruit as well. Have not tested them, just figured they cost more and Adafruit is respectableCurrently, I have a bunch of (clearly counterfeit) STM32F103s in them, and a bunch of TO-92 parts that have been previously breadboarded. I prefer to put parts back in their bags instead.

author: mmagin
author_rank: Frequent Contributor
timestamp: March 31, 2016, 09:57:38 pm
content: Quote from: dadler on March 31, 2016, 08:19:55 pmYeah, I was kind of unsatisfied by their answers:https://forums.adafruit.com/viewtopic.php?f=19&t=90445Now that I have more means than just the cheap surface resistivity meter at my disposal I might do something more thorough and write up my results eventually.Admittedly, I fall kind of strongly on the "life is too short to waste lots of time on mysterious ESD-related failures" and have developed a bit of a ridiculous interest in measuring things.

author: dadler
author_rank: Unknown
timestamp: March 31, 2016, 10:34:47 pm
content: Quote from: mmagin on March 31, 2016, 09:57:38 pmHmm, their answer is "well, if you got scammed, then we did too!"

author: sleemanj
author_rank: Super Contributor
timestamp: March 31, 2016, 11:07:32 pm
content: Just keep your components in ESD bags, put ESD bags in whatever drawers you like.At some point you are going to have to transport said components from drawers to bench anyway so they are going to be in bags for carrying them over there anyway right () so might as well just leave them in the bags all the time.ESD bags are cheap. Conductive foam is not cheap. Buy a heat-sealer (or a metal ruler and use your soldering iron at like 150 degrees or so... use an old bit preferably) to cut-down the bag sizes if necessary to better fit your drawers.

author: Lomax
author_rank: Frequent Contributor
timestamp: March 31, 2016, 11:07:32 pm
content: I was going to get one or two of theESD safe PSC service casesfrom Raaco, with ESD safe inserts. Pricey, but I love the "Handy Box" storage system. They do look to be made from "shiny" plastic, though I have no reason to doubt Raaco's quality!

author: jitter
author_rank: Frequent Contributor
timestamp: April 01, 2016, 08:16:30 pm
content: Quote from: Lomax on March 31, 2016, 02:28:19 pmOne thing to remember with ESD precautions is that grounding must not be "hard" to ground, but through quite some resistance, like at least 1 MOhm.Also remember that discharges only occur when voltage differentials are allowed to exist. So before you take the new part out of the ESD safe box, make sure you and it are at the same potential.I work in an EPA (ESD protected area) which means floors tables, chairs, container, etc. are all earthed. No ESD unsafe plastics are allowed, preferbly also no cardboard. ESD safe shoes or straps are worn and a labcoat with carbon fibre is also mandatory. At home, you don't need to be this rigorous, just apply some common sense.