Static electricity safety

[CTho9305]

To keep hardware safe, should it be stored with in an insulator, a good conductor, or something with very high resistance (megaohms) but that does conduct some? Intuition leads me to believe the third option is best because stuff shouldn't be able to build up a charge, and if you touch it after walking across a carpet, the current should be minimal. On an insulator, charge could build up to jump all at once (isn't that basically WHY non-conductive stuff such as carpet gets you zapped?)

 

[FrankSchwab]

Generally, a conductive but high-resistance substance is used for anti-static protection, for precisely the reasons you mention. Insulators have a nasty habit of building up static. Good conductors have the problem that, should a static charge be induced, it will discharge rapidly (think touching a doorknob) possibly causing damage due to the momentary high currents. High-resistance conductors will drain the charge slowly, preventing the damage that a spark might cause but still safely dissipating the charge in a relatively short period of time. Most anti-static gear (table mats, wrist straps, etc) use resistances measured in megohms or 10's of megohms.

/frank

 

[lobadobadingdong]

I generally discharge any built up static before touching sensitive equipment any way so it doesn't much matter in that reguard unless you have no place to ground yourself before handling the said equip.

build a device any fool can use and only a fool will use it. ~unknown~
"wit is educated insolence" ~ Aristotle ~

 

[Akira13]

I always figured it was safer to store in a conductor because charge moves to the outside of a conductor (Physics 122).

 

[sao123]

I think that anti-static bags (for storing PC cards) rely on the Gauss Law principle. When you have a hollow space, surrounded by a conductive shell surface, due to the charge distribution vectors, no current can physically enter the hollow space.

 

[Mday]

Originally posted by: sao123
I think that anti-static bags (for storing PC cards) rely on the Gauss Law principle. When you have a hollow space, surrounded by a conductive shell surface, due to the charge distribution vectors, no current can physically enter the hollow space.

no, they work by the fact that they are conducting with a high resistance. there are conductive dopants in the plastic.

gauss's law works in ideal situations btw.

 

[sao123]

Gauss law works in practical situations too. Most cars use it to create a safety feature, for if the car gets lightning struck, the inside is safe.

 

[Peter]

THAT would be the Faraday cage principle.

 

[Akira13]

Originally posted by: Peter
THAT would be the Faraday cage principle.

? I thought that was EM waves.

 

[Akira13]

Okay, so if static safety requires a conductor of high resistance, then why do we store semiconductors (IC's and whatnot) in (very) conductive foam?

 

[FrankSchwab]

Originally posted by: Akira13
Okay, so if static safety requires a conductor of high resistance, then why do we store semiconductors (IC's and whatnot) in (very) conductive foam?

Have you ever measured the resistance of that foam? Don't make assumptions about it's conductivity until you do.

/frank

 

[Akira13]

Originally posted by: FrankSchwab

Originally posted by: Akira13
Okay, so if static safety requires a conductor of high resistance, then why do we store semiconductors (IC's and whatnot) in (very) conductive foam?

Have you ever measured the resistance of that foam? Don't make assumptions about it's conductivity until you do.

/frank

I stand corrected. My DMM tells me that "conductive" foam actually has very high resistance ( > Mohms).