I've purchased a large batch of items, varying from capacitors to potentiometers to ICs and would not like to ruin the investment in a careless mistake.

I have a metal filing cabinet from IKEA that sits between the carpet and my wooden desk, would there be any harm from to the components just being in there?

I have many Styrofoam blocks to place components (that can be) placed shoved in them, as well as a lot of baggies. Would dryer sheets laced under/between these packages keep them safe - at least from common worries?

I could buy some sort of wrist strap, however am not sure if just touching the metal cabinet or something like a metal window frame would discharge static (even if not "grounded" directly to earth through socket or something), if that works, and the dryer sheets could prevent discharge within the filing cabinet that would put my mind at ease.


2 Answers 2


Styrofoam is ESD death, alas.
Some people wrap it in Al foil but blowing up a few photos of ICs with this done will show you that its very very easy to get a pin through a hole in the AL that does not touch metal but does touch foam. Murphy will have no problem t all blowing up your better ICs this way. Wrapping loosely in Al foil is safer.

Break some styrofoam in pieces. Get a nice warm dry room - heater or whatever.
Rub favorite spark making jersey with a balloon or similar.
Stick styrofoam to balloon and you and jersey with ESD.
Consider implications.
Discard all styrofoam IC mounting foam. .

After years of thinking about it and playing and looking at electron microscope blowups of fantastic craters blown in tracks and silicon by ESD I have concluded that

  • The problem is real

  • The problem is on average over hyped by those who seek to make money from it.

  • Failure to take some sort of protection WILL cause you problems - massive ones in some cases.

  • You can get quite good results at not too great cost.

Modern carpets and most "linos", clean dry air conditioned buildings, crisp and tidy modern desktops and materials and similar are heaven for ESD generation and charge retention.

Bare concrete floors, wooden desks, moist air etc are liable to vastly reduce ESD hazards - but no guarantees.

Carpet sprays which stop the carpet zapping you will often not stop the carpet zapping your ICs.

Some devices are far more prone to damage than others. MOSFET dates, most LEDs, ICs without protection diodes (as eg SOS may be) ... .

Long long ago we erased EPROMS in sunlight on a smooth brick window sill. Many died. Once we did it on a sheet of Al none ever again dies. ESD charge on user in office environment and toasty war and dry conditions = fatal.

Grounding earthstraps via a 1 Mohm or more helps you stay alive and makes ESD contact less painful and stops sudden current peaks on discharge (which may or may not matter).

I've never used heel grounders or ion blowers (but have seen them used in top Chinese factories) - seldom needed in amateur environments.

Common sense - "what would a charge want to do here?" type approach is usually useful. Do be aware how charge behaves - pulling apart two items in a field may end up with opposite charge on each etc.

"Vaguely conductive" is usually good enough. Wood is good - except perhaps if highly varnished etc. An old pitted desk surface is liable to be ESD freeish and have a leakage path to earth even if not grounded. (Who ever grounded w a wooden desk?:-) ).

Touching a metal parts cabinet will probably make you ESD free enough to handle parts if you stay in contact (a slide of the foot while standing by a cabinet if not touching it can raise you to kVs in a moment.)

BUT when you carry your parts to a work desk you may all then be at 10 kV. Grounding yourself to a new surface via a say 10 Mohm+ resistor will equalise you not too fast and may reduce pain too. (Long ago we would on occasion form a line of people holding hands and all would shuffle together across the carpet tus building up an N-bodies charged capacitor. The leader would reach out and touch a newcomer - ZAP - we ALL felt the shock as charge transferred down the line. )

Storage in conductive trays and tubes wise BUT most seem OKif other cautions taken.

Interior layer of cooking Al foil works.
A light spray with Nickel shielding spray renders any plastic container bulk conductive. Spray is expensive but goes a long way.

Butyl rubber sheet (used for roofing) makes good ESD mat at far less price than "ral" mat. Offcuts and bale wrappers may be even cheaper. Set ohnmeter to say 100k to 10M ohms range. Push robes deep into run=bber VERY close to each oter but not touching. ANY sign of conduction is enough. SOME rubbers are very ,ow R and may cause problems if working PCBs placed on them.

Many conductive surfaces will produce magic smoke if PCB with mains on solder leads on bottom is placed on the surface. Very exciting. Try to avoid.

  • 1
    \$\begingroup\$ I very much enjoy reading your answers, thank you for the writeup. I used my Styrofoam for a few buttons and old LED's before the purchase, I'll be sure to not use them now. :) Happy it is easier to keep them safe with a little knowledge. \$\endgroup\$ Nov 23, 2011 at 1:34
  • 3
    \$\begingroup\$ Clothing is also a factor. Stand up in winter from a non-grounded office chair, wearing a woolen sweater and well-insulated shoes (sneakers), and you can draw a 5mm spark. \$\endgroup\$
    – starblue
    Nov 23, 2011 at 7:15

Some additions to what Russel said:

  1. Make your environment 'reasonably' ESD safe. that includes NO STYROFOAM. A somewhat conductive floor and desktop will help a lot (old-style linoleum, wood). Don't put on your wool clothing. Have a few plants and water them well: keep humidity > 50%. no problem in my country :(

  2. Take extra measures for ICs and MOSFETs only (don't bother with capacitors, resistors, etc). Store them in contact with something that conducts slightly: the original pipes they came in, the black plastic bags they are sometimes packed in (NOT garbage bags!), the black foam that is sold for this purpose, alu foil if you don't have anything else (only the dull side is conductive!).

  3. Most modern components have some ESD protection built in. Avoid those that don't (older CMOS chips, a lot of MOSFETS), or take extra precautions, like connecting yourselve to earth (ground) via a suitable resistor ALL THE TIMES. If you are really paranoid (or you live in a low humidity environment) that includes 'while you are walking'!

  4. Circuits that contain (very) sensitive chips must have 'bleeder' resistors. Example: uC output to MOSFET gate. There should be a resistor there for other reasons too. Something to watch out for when you design your own circuits.


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