I have a few minor edits to suggest for the ESD article

http:// www.allaboutcircuits.com/vol_3/chpt_9/1.html

In a couple of places, the current that may be associated with static electricity is treated a little too casually, in my opinion, as in the quotes "there is no current capacity behind it. " and "Static electricity is voltage with no real current".

Static electricity may discharge in a wide range of currents, both small and large (think lightning) so I think that low current when the stored charge flows is not a consistant property of static electricity.

Is this quote from the article really true: "pulling tape off a dispenser can generate millions of volts"? I'd be surprised. Most articles I've casually browsed suggest that a million volts will spark at least several feet! I can't imagine a tape dispenser generating this much voltage.

And about this quote "continuously bleeding off this voltage is needed." I would say that what is bled off is charge. Voltage is a property of this charge, and while it's true that bleeding off charge results in bleeding off voltage, I think that charge is more fundamental thing.

 

Pulling tape off a reel in a vacuum will generate x-rays, this published in a recent article published by the site http://www.physorg.com/. The number has been stated in more than one source concerning ESD control. Transparent tape is an excellent insulator, as well as an excellent static electricity generator (the two aren't the same).

You have to look at the focus of the article, which is ESD control on a work station handling ESD components. Lightening is an ESD event (which was pointed out in the article), but doesn't really apply in context of what the intent of the article was.

Charge in this case is measured in voltage. At the end of the day, it is voltage that counts. During a ESD event this voltage translates into current, but it is the voltage that ionizes the air and creates the initial discharge.

 

Did a search and found the article...

http://www.physorg.com/news143900979.html

 

That's an amazing tape phenenomon!

But still, as I remember from repairing color TV sets back when they had big glass tubes, it only takes about 30 kV to generate a harmful amount of X-rays.

It's really the electric field, as measured in the volts per meter, not the voltage itself, that ionizes air and causes a discharge. I found a nice description at this link -

http://www.myelectricengine.com/info/plasma-physics/plasma-physics.html

I'm only including this link out of general interest; I understand that it goes into much more detail than the article intended to go.

 

Don't worry about the link.

Never Stop Learning or Building!

 

Tell you what, you bring up some valid points about the magnitude of voltages. I'm going to do a bit more research and get back with you.

 

OK, this fell through cracks, but I did do the research. Second paragraph...

ESD comes in many forms, it can be as small as 50 volts of electricity being equalized up to many millions of volts. The actual power is extremely small, so small that no danger is generally offered to someone who is in the discharge path of ESD. It usually takes several thousand volts for a person to even notice ESD in the form of a spark and the familiar zap that accompanies it. The problem with ESD is even a small discharge that can go completely unnoticed can ruin semiconductors. A static charge of millions of volts is common, however the reason it is not a threat is there is no current capacity behind it. These extreme voltages do allow ionization of the air and allow other materials to break down, which is the root of where the damage comes from.

Should read...

ESD comes in many forms, it can be as small as 50 volts of electricity being equalized up to tens of thousands of volts. The actual power is extremely small, so small that no danger is generally offered to someone who is in the discharge path of ESD. It usually takes several thousand volts for a person to even notice ESD in the form of a spark and the familiar zap that accompanies it. The problem with ESD is even a small discharge that can go completely unnoticed can ruin semiconductors. A static charge of thousands of volts is common, however the reason it is not a threat is there is no current of any substantial duration behind it. These extreme voltages do allow ionization of the air and allow other materials to break down, which is the root of where the damage comes from.

Side note: I tried very hard to pin down the voltage generated when scotch tape generates x-rays in a vacuum with no luck. The most comprehensive article was found here. Apparently it takes 15keV to do this, my understanding of physics in this area is a bit shaky, but I don't think this translates to 15KV.

I would put the criticism as verified.

 

7th Paragraph down...

There are a lot of activities that generate static, which you need to be aware of as part of an ESD control regimen. The simple act of pulling tape off a dispenser can generate millions of volts. Rolling around in a chair is another static generator, as is scratching. In fact, any activity that allows 2 or more surfaces to rub against each other is pretty certain to generate some static charge. This was mentioned in the beginning of this book, but real world examples can be subtle. This is why a method for continuously bleeding off this voltage is needed. Things that generate huge amounts of static should be avoided while working on components.

Should be...

There are a lot of activities that generate static, which you need to be aware of as part of an ESD control regimen. The simple act of pulling tape off a dispenser can generate extreme voltage. Rolling around in a chair is another static generator, as is scratching. In fact, any activity that allows 2 or more surfaces to rub against each other is pretty certain to generate some static charge. This was mentioned in the beginning of this book, but real world examples can be subtle. This is why a method for continuously bleeding off this voltage is needed. Things that generate huge amounts of static should be avoided while working on components.

 

Bill,

I have entered the change at ibiblio.

Dennis