I started this thread because i've always used antistatic bags (just because i've got a few over the years), and now i've just been told that they're CONDUCTIVE!
I use them to sit my Arduino boards on.
So now i'm measuring the conductivity of them all lol.
![AntiStatic[1].jpg](https://europe1.discourse-cdn.com/arduino/original/3X/7/b/7bc5f15e1fb7b94b32e94f4f594d96dfe8500d63.jpg)
I've never been able to get a reading out of any of them though. Can you? The spec I've seen on the pink bags is 1011 ohms/square. My meter isn't good enough to detect that. Just enough to dissipate a little static.
The silver static shielding bags I think are a layered construction, a metallized layer between two layers of plastic. I can't get a reading on those, either. Perhaps puncturing them would contact the metal and then they'd show some non-infinite resistance.
It is the black plastic ones that have a measurable resistance. About 1K per square.
nope, i can't get a reading... but i'll check them all eventually.
If a multimeter can't read the value, i'm sure my arduino's going to be safe sitting on it.
Grumpy_Mike:
It is the black plastic ones that have a measurable resistance. About 1K per square.
Ah. Have not had any of those. Some of the black foam is quite conductive as well.
cjdelphi:
If a multimeter can't read the value, i'm sure my arduino's going to be safe sitting on it.
I'd think so.
Pink antistatic bags and foam are "static dissipative", and have a very high resistance. The silvered bags are "static shielding" and have a metalized layer between plastic layers.
It is the black satin finish bags and foam that are highly conductive, often used in pressure sensor projects. At one time, that and aluminum foil were the only antistatic materials used. So some of us older experienced techs automatically shy away from setting powered up boards on antistatic bags.
Dave Jones of EEVBlog has done a few videos about antistatic bags and antistatic mats.
3:36 is where the antistatic stuff starts:
Antistatic bags revisited:
Antistatic mats tested for circuit disturbance:
This static charge detector is ridiculously sensitive, responding to voltages well below the danger threshhold. But it is great for illustrating just how prevalent static electricity is:
http://amasci.com/emotor/chargdet.html
If the metal layer is in a sandwich it won't stop static. Static lives on the
surface layer of good insulators (which is why humid conditions prevent
static - above a certain density of water molecules on a surface the whole
surface becomes slightly conductive).
This is actually an issue for precision circuit design since the surface of a
PCB will support leakage currents in the pA to sub-nA range in humid
conditions and some precision CMOS opamps have input current specs of 0.1pA!
Conformal coatings are one approach to reduce the problem.
Static involves voltages in the kV range and amounts of charge in the nC
range, so that 10^12 ohms is the sort of resistance that leaks static away
quickly! 10^15 ohms is the sort of resistance needed to allow static to linger
around and do hair-raising experiments! For instance wood cannot get near
these values, even if kiln-dried, whereas glass and many polymers can.
It should be easy to test the other half of the issue that James C4S brought up on the other thread. Does your Arduino board actually short out when you run it when placed on an anti-static bag?