ESD damage and relative humidity

About 4.3%, or 100/(e^pi) as a first good approximation, although bilateral effects caused by Cauchy scattering have some effect in areas of significant frombulism.

Cheers

--
Syd

Bwahahahahahahaha >:-} ...Jim Thompson

-- | James E.Thompson | mens | | Analog Innovations | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | San Tan Valley, AZ 85142 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

| 1962 | I love to cook with wine. Sometimes I even put it in the food.

Don't know about 100%, but:

Remember that junction failure isn't the sole possible outcome of an ESD event. Weakening ("degrading" in ESD parlance) of junctions will shorten operational life, not evident immediately after an event.

3M has a nice handbook:

I've not found a 100% RH voltage value anywhere.

With polyester carpet, I think even underwater you could get a healthy shock! (c;

Pretty low. Unless there is an electric eel nearby.

Matt Roberds

I wanted to have all our assembly done by naked girls sitting in tubs of tepid water. That didn't appeal to management.

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John Larkin Highland Technology Inc

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Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators

You'd have to employ girls free of discharge.

So, it was the tepid water they objected to?

Chilly water makes for more turgid nipples.

You should be able to model the situation with your circuit connected by a variable resistance to a charged capacitor. Some of the charge will bleed to nearby ground planes, while the rest goes to ESD sensitive parts.

With a constant voltage source (say 10 kV) connected to the capacitor a few cm from the device, the maximum constant leakage current can be calculated.

Alternatively, charge up the capacitor and let it discharge through the resistance and get the RC time constant for different distances.

If a charged finger moves towards the device at constant speed, the resistance drops rapidly, discharging the human body model capacitor. How low does the voltage drop just before contact ?

Some interesting data can be found with Google search expression like "moist air conductivity" (with quotes). It appears that the air conductivity will increase with at least two orders of magnitude, when going from dry to moist air.

They objected to the nipples or the turgidity? We need to get to the root of the problem. Or something.

Very unlikely. 100% humidity means that it's raining. Thanks to acid rain, the water is sufficiently conductive to short out any buildup of static electricity.

However, there is the possibility of precipitation static. It's much like rubbing plastic to build up a static charge except it's charged rain drops rubbing against plastic, or fiberglass, and leaving some electrons behind. The water simply delivers a charge from the clouds to your circuit. Examples: While the radio interference is obnoxious, there really isn't enough charge to do much damage unless your device is exposed to the rain directly and you're using unprotected static sensitive devices.

--
Jeff Liebermann     jeffl@cruzio.com 
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Skype: JeffLiebermann     AE6KS    831-336-2558

Soldering, or mechanical assembly? There are places *I* never want to feel a drop of hot solder and I am sure ladies have similar concerns.

Mechanical assembly might be OK as long as you don't mind occasionally losing washers and stuff down the tub drain, and having to replace rusty hand tools.

They wanted naked old people instead?

Matt Roberds

Blame Milla Jovovich. OMG! They're full of milk!

DAMNIT, Janet! *I* wanted to marry her!

We'll never find out now! She'll probably never sport those torpedoes in a flick again. It is truly a sad day. :-(

(just kidding)

I'd worry more about moisture in the IC package cracking when its soldered to the board. BTDT, on a run of boards with improperly stored MC68340 processors.

--
Anyone wanting to run for any political office in the US should have to 
have a DD214, and a honorable discharge.

They have an aversion to soggy, fat & ugly assemblers? ;-)

--
Anyone wanting to run for any political office in the US should have to 
have a DD214, and a honorable discharge.