Dust filled computer

[Dave C.]

NOOOOOOOO!!!!!!!!!!!!!!!

And the case is grounded thus discharging any static directly to
earth...

Yeah, straight through delicate ICs, frying them in the process. -Dave

 

[Al Dykes]

And the case is grounded thus discharging any static directly to
earth...

The static charge is accumulated on the vac noxxle, and when the
charge is high enough, and the nozzle is close enough to a part of the
computer you get an arc.

If the arc connects to a chip, the chip is taost.

 

[Conor]

Yeah, straight through delicate ICs, frying them in the process. -Dave

ROFLMAO, how ignorant?

THats ground as in EARTH, not ground as in 0V.

 

[Dave C.]

ROFLMAO, how ignorant?

THats ground as in EARTH, not ground as in 0V.

You think a case being grounded is going to save an IC from static
electricity? Actually, the case being grounded will just help attract
static electricity. Electricity wants to go to ground. Now who's
gnorant? -Dave

 

[ToolPackinMama]

The static charge is accumulated on the vac noxxle, and when the
charge is high enough, and the nozzle is close enough to a part of the
computer you get an arc.

If the arc connects to a chip, the chip is taost.

May I ask, have any of you actually done this? Or witnessed it?

 

[Al Dykes]

May I ask, have any of you actually done this? Or witnessed it?

Who knows why a circuit board stops working (unless you have a million
$$ lab that can disect IC packages and look at chips under electron
microscopes) ? A static discharge that is below human perceptiion can
weaken an IC chip and cause it to fail days, months, or years later.

I have a good antistatic strap and use it under the following conditions;

- The part I'm handling has to work and I don't have a spare on hand
and if I don't get this system running it will be a major screwup.

- The part is more expensive than I want to risk paying for, even of
it's the company's money.

- I'm working if front of the client and don't what any coulda-shoulda
hindsight if anything goes wrong, even if it's not static.

If I don't use the strap I always grap the chassis and keep a bidy
part in contact while I handle the part, so when the part comes close
to the motherboard it will be at roughly the same potential voltage.

Outside the computer business I've used industrial blower equipment
that genererated fearsome static whacks every few minutes if the
equipment, and I, were not properly grounded. Enough to knock me off
a ladder.

A google search for anti-static info will turn up lots of pages like
this: (chips are a little more fragile than assembled boards.)

http://www.intersil.com/data/tb/tb52.pdf

 

[ToolPackinMama]

Who knows why a circuit board stops working (unless you have a million
$$ lab that can disect IC packages and look at chips under electron
microscopes) ? A static discharge that is below human perceptiion can
weaken an IC chip and cause it to fail days, months, or years later.

So, in other words... no.

 

[John Doe]

Al Dykes wrote:

May I ask, have any of you actually done this? Or witnessed it?

A few opinions derived from much reading and lots of personal experience.

Static electricity moves pretty fast to be witnessed. Determining what
caused a system to fail is impossible for most of us.

If you're asking about whether static electricity can damage components,
the answer is a no-brainer yes. So you do need to avoid it around
electronic components, whatever it is.

Digital components are much more nearly immune to static electricity
discharge than analog components, however there are analog components in a
computer system.

I'm not sure whether the nozzle or the airflow itself can cause static
electricity, I have heard it's the airflow.

I have handled lots of add-in cards and mainboards without having any of
them fail. I have handled operational amplifiers and seen them fail
apparently do to static discharge which I did not see or feel at the time.

I would just keep in mind how much the component or system you're handling
might cost to replace if need be, and do further research if necessary.

 

[Conor]

You think a case being grounded is going to save an IC from static
electricity?
Yes.

Actually, the case being grounded will just help attract
static electricity. Electricity wants to go to ground. Now who's
gnorant? -Dave

You - still.

Me, qualified and experienced electronics engineer. You?

 

[Conor]

Static electricity moves pretty fast to be witnessed. Determining what
caused a system to fail is impossible for most of us.

But not for some of us. However you refuse to listen to those with real
world experience.

If you're asking about whether static electricity can damage components,
the answer is a no-brainer yes. So you do need to avoid it around
electronic components, whatever it is.

Modern electronics are far more resistant to static electricity than
they used to be. Even 15 years ago, TTL was pretty much immune - it was
only CMOS ICs you needed to worry about.

Digital components are much more nearly immune to static electricity
discharge than analog components, however there are analog components in a
computer system.

I'm not sure whether the nozzle or the airflow itself can cause static
electricity, I have heard it's the airflow.
Correct.

I have handled lots of add-in cards and mainboards without having any of
them fail. I have handled operational amplifiers and seen them fail
apparently do to static discharge which I did not see or feel at the time.

I would just keep in mind how much the component or system you're handling
might cost to replace if need be, and do further research if necessary.

Its a PC. It'll be obsolete and get upgraded long before static damage
rears its head.

 

[Al Dykes]

So, in other words... no.

Given that voltages lower than the level of human perception
can damage ICs, it's easy to understand wht I can't point
to some instantaneous cause and effect, it's understandable.

 

[Dave C.]

Me, qualified and experienced electronics engineer. You?

I don't know what you are Conor, but if you think a case being grounded is
going to save an IC from damage by static electricity, you are NOT an
electronics engineer. Anyone with a basic understanding of electricity
knows that it will seek the shortest path to ground. If that path happens
to be through an IC, then the IC is toast. If the case is grounded, the IC
is STILL toast. If anything, the case being grounded makes static buildup
in a vacuum cleaner attachment more dangerous, as it emphasizes the
potential difference. You could try to ground the vacuum cleaner to prevent
that, but as plastic doesn't conduct electricity very well, good luck on
that. -Dave

 

[Al Dykes]

But not for some of us. However you refuse to listen to those with real
world experience.

Modern electronics are far more resistant to static electricity than
they used to be. Even 15 years ago, TTL was pretty much immune - it was
only CMOS ICs you needed to worry about.

Correct.

Correct what ? It's the aiirflow.

Its a PC. It'll be obsolete and get upgraded long before static damage
rears its head.

You should put an "IF" in front of that sentance.

Some of us work on equipment that costs much more that a PC, runs for
years, and if down for unscheduled service will cost my company, or my
client's company significant financal loss. Others work where people
can die if equipment fails.

Yes, assembled boards are pretty safe to handle, but as I said, If I'm
not prepared to eat the cost of a part, or I don't have a pile of
spares on hand, I take precautions.

All descriptions of the effects of static discharge on components
state that the effect may be delayed, so why should I take chances
when I handle a $300 CPU, or $150 GB memory module.

this page has some specifics; .

http://www.esda.org/esdbasics1.htm

 

[ToolPackinMama]

A few opinions derived from much reading and lots of personal experience.

Do you personally know of one such case? Have you personally ever
verified that it's true?

 

[ToolPackinMama]

Given that voltages lower than the level of human perception
can damage ICs, it's easy to understand wht I can't point
to some instantaneous cause and effect, it's understandable.

I'm just wondering if you know of even one case where that actually
happened. If that has occurred, what are the signs that it has
occurred? Maybe one can't see the offfending spark, but surely the
after-effects of such damage are immediately obvious, yes?

 

[ToolPackinMama]

I don't know what you are Conor, but if you think a case being grounded is
going to save an IC from damage by static electricity, you are NOT an
electronics engineer. Anyone with a basic understanding of electricity
knows that it will seek the shortest path to ground. If that path happens
to be through an IC, then the IC is toast. If the case is grounded, the IC
is STILL toast. If anything, the case being grounded makes static buildup
in a vacuum cleaner attachment more dangerous, as it emphasizes the
potential difference. You could try to ground the vacuum cleaner to prevent
that, but as plastic doesn't conduct electricity very well, good luck on
that.

Hmm. Plastic doesn't conduct electricity very well. Hmm.

 

[Al Dykes]

I'm just wondering if you know of even one case where that actually
happened. If that has occurred, what are the signs that it has
occurred? Maybe one can't see the offfending spark, but surely the
after-effects of such damage are immediately obvious, yes?

As I've said several times, a static discharge too low to be perceived
by you are me may damage an intergated circuit and the effect may not
be immediate. If you have an electron micrscope, the damage can be seen
before the chip fails, it the IC package os opened up and the chip examined.

NASA and the military test for, and control static around electronics
all the time.

For your PC, I don't care if you fry it.

 

[Dave C.]

Hmm. Plastic doesn't conduct electricity very well. Hmm.

No, it doesn't. It makes a heckuva collector of static electricity,
hough. -Dave

 

[ToolPackinMama]

No, it doesn't. It makes a heckuva collector of static electricity,
hough. -Dave

I believe you.

Can you perhaps explain to me why a vaccum cleaner drawing air into
itself is more dangerous than case fans and heatsink fans which
blow/suck air? It seems to me that the basic principles are the same.

 

[Al Dykes]

I believe you.

Can you perhaps explain to me why a vaccum cleaner drawing air into
itself is more dangerous than case fans and heatsink fans which
blow/suck air? It seems to me that the basic principles are the same.

Because in a PSU the exhaust air is being blown thru some grill
that is grounded that drains the charge buildup.

When air passes over an insulator, like thru a plastic hose, there is
a charge buildup until the arc-over voltage is reached or some victim
comes along. Some plastic has additives that make it conductive enough
to not accumulate a charge.

Did you take high school physics ?

A google for "physics static electricity" will answer your questions
about the exact mechinism.