ESD: fact or 3M scam?

Here at work we are preparing for an ESD (ElectroStatic Discharge) audit. A lot of it seems to be piddly, ridiculous, BS! I realize that ESD is real, and it does damage components. But, in my opinion it isn’t that much of a threat, as long as people just use some common sense. Is it really cost effective for companies to shell out thousands of dollars just to help save a few components?

I used to quality-test circuit boards. We had to wear a wrist band with a grounding wire and use specially made, electrically-grounded, mats when handling such boards or individual chips.

If ESD can wipe out the information programmed into a chip, then there’s a very real potential (no pun) to wipe out a whole motherboard of chips. I suppose it’s very real, but I don’t know…

It always puzzled me, too.

  • Jinx
    Just because you’re not paranoid, doesn’t mean we’re not out to get ya! :wink:

In Jinx case maybe. But we’re a service dept. and we don’t even manufacture our own boards. Once a board is assembled the risk of ESD damage drops big time. That and a lot of our repairs are mechanical not electrical (for a glimpse of what we repair go to http://www.flir.com and look at anything AIRBORNE). What I’m saying is, what does it matter if I’ve got a ceramic mug on the back corner of my bench that I use to hold all of my pens and pencils? Isn’t it bad enough that I have a 17" computer monitor here on the same bench?

The problem is the latent failures. The part doesn’t fail completely until it has been installed in something, like the traffic controller on the corner, the computer in your car, The heart-lung machine in the OR, or simply something that is used in a business process where failure can cause thousands of dollars in losses. Here’s a link:

http://www.desco.com/aboutesd.htm

Qualifier-This is a company that sells products for ESD control.

Qualifier-This is a company that sells products for ESD control.

You see, this is exactly what I’m talking about. Are companies alive and thriving just because CEO’s become convinced that this is SUCH A SERIOUS CONCERN!?!?!?

Maybe not if it is quick and easy to replace the components. But if you are in a large final test of hardware that is worth boocoo bucks, then the cost to replace a few components is enormous.

As an example. Let us say you are building a large widget. The widget consists of multiple circuit boards in multiple packages. There are probably subassembly tests of the multiple packages. ESD failures at that point might be relative inexpensive. But when the complete widget is assembled, a part failure due to ESD is very expensive due to loss of all of the manhours of testing already completed, the assembly time and the cost to the possible schedule hit. So at that point it is definitely worth the companies $$ to invest in ESD products.

Also, some semiconductor materials are more sensitive to ESD problems than others.

The ESD problem involves input MOSFET devices. MOSFETS are very sensative to transient voltages because of their high impedance bases (if you understand transistors, I suppose you probably already know this, so why am I talking like this?)

The input(base) to a MOSFET transistor is basically a super-capacitor (in fact, mosfet transistors are often used as capacitors). It is comprised of an ultra-thin dialectric material. If too high of a voltage is applied to this then the dialectric can break down, causing the transistor to fail.

Of course, this applies to all MOS devices: PMOS, NMOS, CMOS.

Because FET devices are theoreically voltage controlled they do not have a path for current. The average person can accumulate thousands of volts of static electricity on them, damaging the devices.

Make sense to anyone?

A lot of ESD rules used by companies these days is pure BS, and the reason why is simple. How do you regulate a little common sense? You can’t. But, you can make extremely strict rules that even an idiot has a hard time screwing up. Then you can prove to someone else that your stuff is safe, which you can’t do just by saying hey, our employees aren’t as dumb as mud.

I’ve seen bare circuit boards come in anti-static bags with an ESD warning label on them. Heh.

Erislover, I’m a little confused by your comment that an FET has no path for the current, because I can see plenty of paths for current to go through. Don’t think of transistors as switches, think of them as devices that are never all the way on or all the way off.

FYI - it’s not just thousands of volts, but easily tens of thousands of volts. If you can feel the static shock and see a little blue spark, then you’re probably up around the 20 to 40 kV range, maybe even higher.

satanslawyer - ESD aint got nuthin on six sigma.

I used to sell electronic components to the industry (diodes, transistors, MOSFETS, ICs, etc.). FORD was so hung up on ESD that they wanted EVERYTHING that the parts were shipped in to be ESD safe/conductive! 3M made a FORTUNE on us! For instance, the carrier tape had to be conductive-cost 4X standard tape. The reels had to be conductive-cost 10X stabndard. AND (get this) the conductive plastic was NOT RECYCLABLE!
Thos guys at 3M are marketing geniuses!