Static is [not] your friend - vacuuming PC?

[Sammo]

In terms of static, how safe is it to clean inside a home PC by using
a vacuum cleaner?

Some people like this website suggest that it is unwise.
http://www.dansdata.com/sbs3.htm

If my PC is switched off but remains earthed (to the mains earth) and
I am careful not to do physical damage to the PC with my home vacuum
cleaner, then surely there is no problem with static?

Am I overlooking something?

Sammo

--

 

[Guest]

In terms of static, how safe is it to clean inside a home PC by using
a vacuum cleaner?

Some people like this website suggest that it is unwise.
http://www.dansdata.com/sbs3.htm

If my PC is switched off but remains earthed (to the mains earth) and
I am careful not to do physical damage to the PC with my home vacuum
cleaner, then surely there is no problem with static?

Am I overlooking something?

Electrostatic discharge can produce some intersting effects
on semiconductors and the risk shouldn't be discounted.

However I have cleaned out the interior of countless cases
with no apparent ill effect- using a soft haired paintbrush
in one hand whilst hovering over the area with the nozzle of
a domestic vacuum cleaner in the other. Due to the nature of
the job, one hand or both is in contact with the case most
of the time and so there is little chance for static build
up on the nozzle/your body/brush. Touching the case before
introducing the brush is a good idea.

Personally, I prefer to have the case sat on an esd mat to
leaving it plugged in - not so much from the static point of
view but a marked reluctance to work on anything with power
on or connected, unless unavoidable (like, I don't have the
mat with me).

Not to be done to a laser printer, but for other reasons.

 

[Cuzman]

" In terms of static, how safe is it to clean inside a home PC by using a
vacuum cleaner? "


IMO it's still not safe at all. Buy a can of compressed-air from an
electrical hardware store.

 

[Watson A.Name - \Watt Sun, the Dark Remover\]

In terms of static, how safe is it to clean inside a home PC by using
a vacuum cleaner?

Some people like this website suggest that it is unwise.
http://www.dansdata.com/sbs3.htm

If my PC is switched off but remains earthed (to the mains earth) and
I am careful not to do physical damage to the PC with my home vacuum
cleaner, then surely there is no problem with static?

Am I overlooking something?

Static can be caused by the brush bristles. Use compressed air instead.

 

[Jerry G.]

Using a vacuum cleaner in a PC, or any electronics devices using CMOS
technology is not safe at all. It does not matter how well everything is
grounded. The fact of having a motion contact using device that uses an
insulating material can cause a static build-up. You can read up on static
electricity generation for details.

Even handling the circuit boards under some conditions are at risk for
damage from static electricity. Most of the appliances of today, such as
TV's, radios, VCR's, DVD's, and many other types of devices are using CMOS
devices. Great care should be taken when handling these devices. I have seen
units damaged from improper handling.

The proper way to clean any electronics equipment is to use filtered
compressed air. The unit and the operator of the compressed air must be in
contact to each other in reference to the unit's ground plain (metal case
for example), to prevent any potential difference between them.

The compressed air blown from a distance of at least 6 to 10 inches will
give no effect to build up static charges, and cause any problems with the
device being cleaned.

--

Jerry G.
==========================


In terms of static, how safe is it to clean inside a home PC by using
a vacuum cleaner?

Some people like this website suggest that it is unwise.
http://www.dansdata.com/sbs3.htm

If my PC is switched off but remains earthed (to the mains earth) and
I am careful not to do physical damage to the PC with my home vacuum
cleaner, then surely there is no problem with static?

Am I overlooking something?

Sammo

--

 

[Noozer]

In terms of static, how safe is it to clean inside a home PC by using
a vacuum cleaner?

DON'T DO IT

If my PC is switched off but remains earthed (to the mains earth) and
I am careful not to do physical damage to the PC with my home vacuum
cleaner, then surely there is no problem with static?

By leaving the PC grounded you are giving static a perfect path from the
vacuum, through your parts, to ground... GREATLY increasing the risk of
damage.

Use compressed air!

 

[Floyd L. Davidson]

In terms of static, how safe is it to clean inside a home PC by using
a vacuum cleaner?

Some people like this website suggest that it is unwise.
http://www.dansdata.com/sbs3.htm

The web page descriptions are indeed fairly funny, if you know
what they are talking about. But I highly suspect anyone with a
limited background in Electro Static Discharge will be more
confused than not.

If my PC is switched off but remains earthed (to the mains earth) and
I am careful not to do physical damage to the PC with my home vacuum
cleaner, then surely there is no problem with static?

Am I overlooking something?

Yep. Quite a lot.

*Moving* *dry* *air* around is a great way to build up a static
charge on any component that is an insulator.

Hence *compressed* *dry* *air* and *vacuum* *cleaners* are not
good ideas. In fact, compressed air might be worse because it
can forcefully blast dust into places it wouldn't otherwise go.

If you get enough charge (a few thousand volts, for example, is
common), it will then break down the insulation between the
charge and the next nearest object that is either also holding a
charge or is able to dissipate the charge (e.g., a conductor).
The current flow when that happens is what kills your computer.
And it isn't just that specific current, but also any current
induced into other conductors as a result of that current.

The way to get the dust out of a computer case safely is to use
a damp rag to manually pick up dust. It shouldn't be so wet
that it drips moisture (though that isn't necessarily bad
either, see below), but needs to be damp enough that dust will
stick to it and static cannot build up on it. I personally
prefer to have a large bowl of water mixed with a little
household cleaner (such as 409 or Mr. Clean), in which the dust
rag (a well worn bathroom wash cloth or a thin dish towel, is
nice) is washed as it get dirty. The soapy water in the bowl
should be changed somewhat regularly too, i.e. when it gets so
dirty that as much dirt moves from the water to the rag as from
the rag to the water!

Which type of soap to use does make a difference. The idea is
something that will dissolve any grease film or other coating
that might be present, but even more important is that it be a
good water dispersant. Automatic dishwater soap is perhaps the
best in that respect.

Note that there aren't many things which can actually be damaged
by water itself. Disk drives or CRDOM/DVD drives (things with
moving parts) can be damage by water. But keyboards and
motherboards can be totally immersed in water without damage.
Any time that a system is *really* dirty, or is taken apart for
other reasons, it makes sense to literally wash the device in a
kitchen sink with a solution of soapy water, and then rinse it
off with a water spray if you have one of those handy spray
hoses meant for cleaning dishes.

If the water supply is very hard (filled with minerals) and will
leave a residue, use a final bath of rubbing alcohol. Otherwise
a very dilute solution of automatic dishwater soap is probably best.
(It will leave a very thin film of water dispersant, loaded with
water, on everything. That will help protect against static and
it will also reduce dust build up because of reduced static build
up.)

After such a dunking it takes considerable time to be sure that
the water has dried completely. In places where the humidity is
low that will happen in a day or two anyway, so just put it on
the shelf and wait. Otherwise one method is to use a kitchen
oven on warm, leave the door partially open and put the device
inside the oven for several hours.

But *don't* use compressed air, vacuum cleaners, plastic brushes,
or synthetic cloth to clean a computer. And don't do it on a
day when the relative humidity is 10% either.

 

[Robert Redelmeier]

good water dispersant. Automatic dishwater soap is perhaps
the best in that respect.

Aaaakkk! No! Dishwasher machine soap (Cascade) is one of
the nastiest cleaners I know. Full of trisodium phosphate,
silicates and calcium hypochlorite. Perhaps you mean
dishwasher anti-spot filming agent (JetDry). This stuff
should be very benign when diluted.

Anybody have any good experiences cleaning IBM Model
"M" keyboards in a (soapless) dishwasher?

But *don't* use compressed air, vacuum cleaners, plastic
brushes, or synthetic cloth to clean a computer. And don't
do it on a day when the relative humidity is 10% either.

Well, I guess in AK you have to worry about the latter

I'm less worried about compressed air than I am about vaccuum
because compressed air nozzles are easier to ground and less
likely to contact parts. Static can build up from moving gas
past parts, but the parts should drain that small amount away.
It's bigger (perhaps still invisible) discharges that cause
trouble.

-- Robert

 

[Floyd L. Davidson]

Aaaakkk! No! Dishwasher machine soap (Cascade) is one of
the nastiest cleaners I know. Full of trisodium phosphate,
silicates and calcium hypochlorite. Perhaps you mean
dishwasher anti-spot filming agent (JetDry). This stuff
should be very benign when diluted.

Yep, that's a bad one. Another good wetting agent is Photo Flo,
sold by the gallon for darkroom use (or in smaller quantities at
exorbitant prices).

Anybody have any good experiences cleaning IBM Model
"M" keyboards in a (soapless) dishwasher?


Well, I guess in AK you have to worry about the latter

Depends on where. E.g., humidity in Arizona, New Mexico, and
west Texas is low. It is in the Alaskan interior too.

The current relative humidity here is 70%, and that is typical.

I'm less worried about compressed air than I am about vaccuum
because compressed air nozzles are easier to ground and less
likely to contact parts. Static can build up from moving gas
past parts, but the parts should drain that small amount away.
It's bigger (perhaps still invisible) discharges that cause
trouble.

"Moving gas" is probably one of the *worst* offenders (next to
cats and walking on carpets), and is exactly what is wrong with
using a vacuum cleaner. There is no difference between that
and compressed air, as far as static goes. Grounding the nozzle
is not useful, other than to prevent a direct discharge from
buildup on the nozzle itself. And it is *not* reasonable to
expect either small or large charges to drain harmlessly away
from components.

The whole concept of using moving air is a disaster plan!

Of course, if the relative humidity is 50% or above... the
chances are fair that no damage will be done. If it is more
like 6%, either use full protection or you *will* get bit. (I
lived in Fairbanks for a couple decades, where at -40F in the
winter you can almost be assured that the relative humidity
inside any building that does not have a humidifier will be well
below 10%. You don't need a carpet! Just the wrong shoes or
shirt will be enough...)

 

[CBFalconer]

Static can be caused by the brush bristles. Use compressed air
instead.

<facetious>
Avoid all static problems by using a grounded wire brush <g>.
</facetious>

 

[kony]

DON'T DO IT


By leaving the PC grounded you are giving static a perfect path from the
vacuum, through your parts, to ground... GREATLY increasing the risk of
damage.

Use compressed air!

EXACTLY, though I usually get away with using a dry paint
brush when compressed air isn't handy. There is slight
potential for static but I've never had any damage result.

 

[kony]

Aaaakkk! No! Dishwasher machine soap (Cascade) is one of
the nastiest cleaners I know. Full of trisodium phosphate,
silicates and calcium hypochlorite. Perhaps you mean
dishwasher anti-spot filming agent (JetDry). This stuff
should be very benign when diluted.

Anybody have any good experiences cleaning IBM Model
"M" keyboards in a (soapless) dishwasher?

What do you consider "nasty" about Dishwasher Detergent?

I mean, what harm do you expect?

I have cleaned a LOT of boards in a tub of warm water and
detergent (dishwasher or whatever was handy) with a
paintbrush, it does a great job and the boards worked fine
afterwards, still do. Two important things to do though,
are removing the battery and EPROM first. Of course it's
also necessary to _completely_ dry the boards, including
water wicked under chips and in sockets, which can take a
few days or gentle heating.

 

[Robert Redelmeier]

What do you consider "nasty" about Dishwasher Detergent?

Machine detergent. The pH is around 12 and there's chlorine.
This will cause corrosion of copper and perhaps solder.

I have cleaned a LOT of boards in a tub of warm water and
detergent (dishwasher or whatever was handy) with a

Hand dishwashing detergent is much less corrosive
than the automatic machine variety.

-- Robert

 

[Tzortzakakis Dimitrios]

Yeah-there's no real reason you need to vacuum your PC.Long before you have
damage from dust, you will be upgrading to a new PC (say 5 years, which is a
moderate life span for an ordinary PC0luck or unluck this can be up to 7
years).Before dust will reach dangerous levels, critical components should
fail first.It's not a good idea to open your PC just for cleaning, though.My
vendor told me these things.

 

[Dave Platt]

Aaaakkk! No! Dishwasher machine soap (Cascade) is one of
the nastiest cleaners I know. Full of trisodium phosphate,
silicates and calcium hypochlorite. Perhaps you mean
dishwasher anti-spot filming agent (JetDry). This stuff
should be very benign when diluted.

Anybody have any good experiences cleaning IBM Model
"M" keyboards in a (soapless) dishwasher?

What do you consider "nasty" about Dishwasher Detergent?

I mean, what harm do you expect?[/QUOTE]

For what it's worth... Bob Pease, a respected designer at National
Semiconductor and author of a number of very useful books including
"Troubleshooting Analog Circuits", swears by the use of a dishwasher
for cleaning PC boards especially for high-impedance, low-leakage
circuits. He mentioned the use of a "standard load of Calgonite" as
the cleaning agent... run 'em though the wash cycle, take out after
the rinse, shake off excess water, and allow to air-dry.

Pease comments that after this sort of treatment, leakage currents
across the board surface were often lower than could be achieved using
an expensive commercial solvent-based PC-board-washing system.

For what it's worth, the Calgonite MSDS lists sodium tripolyphosphate,
sodium silicate, sodium carbonate, and sodium sulphate. No
hypochlorites.

In my area (Mountain View, Silicon Valley, fairly hard water) I'd
probably do a final rinse by hand using distilled or deionized water,
to prevent mineral deposits from developing ("hard water" spots). An
anti-spot sheeting/filming agent might eliminate this risk, or might
not... haven't tried it.

 

[kony]

Machine detergent. The pH is around 12 and there's chlorine.
This will cause corrosion of copper and perhaps solder.

Not significant for short-term exposure, in a dilluted bath.
There should be minimum if any copper exposed on a board to
begin with.

Hand dishwashing detergent is much less corrosive
than the automatic machine variety.

Perhaps but it also isn't as good at cleaning. Boards
washed in dishwasher detergent came out looking BETTER than
brand new, even new boards have some residue/flux/etc that
the detergent removes. I don't recommend leaving a board to
soak in it though, generally I submerge them and they're
done within a few minutes or less.

 

[kony]

Yeah-there's no real reason you need to vacuum your PC.Long before you have
damage from dust, you will be upgrading to a new PC (say 5 years, which is a
moderate life span for an ordinary PC0luck or unluck this can be up to 7
years).Before dust will reach dangerous levels, critical components should
fail first.It's not a good idea to open your PC just for cleaning, though.My
vendor told me these things.

It depends a lot on the environment. Too often we assume
queries are only related to home PCs but these days almost
any business has some too.

Your vendor likely told you not to open it to minimize risk
of user-induced problems within the warranty period. They
expect a system to keep running for that period and don't
care as much about longer-term effects. It is a good idea
to open and clean a PC at whatever interval is dictated by
the environment. Often "cleaning" doesn't mean getting
every little spec of dust out, simply checking the primary
fans and heatsink(s) for buildup.

 

[Floyd L. Davidson]

EXACTLY, though I usually get away with using a dry paint
brush when compressed air isn't handy. There is slight
potential for static but I've never had any damage result.

You might as well use a vacuum cleaner. It isn't any worse,
and it is a whole lot easier.

Actually, a "dry paint brush" might be the *worst* thing I've
heard of yet!

*Any* *dry* *insulator* is bad news. Two pieces of paper rubbed
together are bad. One of the worst offenders is putting tape of
any kind onto a static sensitive circuit board, and then removing
it. The potential generated when a one inch strip of tape is
peeled away is just horrendous.

Here's a chart that I found at

http://www.esdsystems.com/training/staticgeneration.htm

They say the data comes from "AT&T ESD Control Handbook-1989".

TYPICAL ELECTROSTATIC VOLTAGES

EVENT RELATIVE HUMIDITY
10% 40% 55%

Walking across carpet 35,000 15,000 7,500
Walking across vinyl floor 12,000 5,000 3,000
Motions of bench worker 6,000 800 400
Remove DIPs from plastic tubes 2,000 700 400
Remove DIPs from vinyl trays 11,500 4,000 2,000
Remove DIPs from Styrofoam 14,500 5,000 3,500
Remove bubble pack from PCBs 26,000 20,000 7,000
Pack PCBs in foam-lined box 21,000 11,000 5,500

The immediate point that comes to mind is how much difference
relative humidity makes, and how something you've commonly been
doing at 70% relative humidity might just blow away everything
if you do it on a day when the humidity is only 10-20%. Look at
"Motions of bench worker"!

 

[Roger Hamlett]

<facetious>
Avoid all static problems by using a grounded wire brush <g>.
</facetious>

Funnily enough, this is the correct answer!...
You can get brushes, with conductive bristles, and a grounding 'tag', that
attaches to the standard fittings used on electronic benches, for exactly
this purpose. On a workbench, with a grounded surface, and filtered
extraction, it allows you to 'de-dust' CMOS components before servicing,
and is standard equipment on a lot of service benches.

Best Wishes

 

[kony]

You might as well use a vacuum cleaner. It isn't any worse,
and it is a whole lot easier.

Actually, a "dry paint brush" might be the *worst* thing I've
heard of yet!

It may seem that way to you but I've noticed static buildup
from vaccume but not from the brush.

*Any* *dry* *insulator* is bad news. Two pieces of paper rubbed
together are bad. One of the worst offenders is putting tape of
any kind onto a static sensitive circuit board, and then removing
it. The potential generated when a one inch strip of tape is
peeled away is just horrendous.

Here's a chart that I found at

http://www.esdsystems.com/training/staticgeneration.htm

They say the data comes from "AT&T ESD Control Handbook-1989".

TYPICAL ELECTROSTATIC VOLTAGES

EVENT RELATIVE HUMIDITY
10% 40% 55%

Walking across carpet 35,000 15,000 7,500
Walking across vinyl floor 12,000 5,000 3,000
Motions of bench worker 6,000 800 400
Remove DIPs from plastic tubes 2,000 700 400
Remove DIPs from vinyl trays 11,500 4,000 2,000
Remove DIPs from Styrofoam 14,500 5,000 3,500
Remove bubble pack from PCBs 26,000 20,000 7,000
Pack PCBs in foam-lined box 21,000 11,000 5,500

The immediate point that comes to mind is how much difference
relative humidity makes, and how something you've commonly been
doing at 70% relative humidity might just blow away everything
if you do it on a day when the humidity is only 10-20%. Look at
"Motions of bench worker"!

Let's put that in context though...
You have a DIP in a tray, or a PCB in a foam-lined box...
are you supposed to just leave it in the box because
removing it would generate static??? Of course not.

If you don't want to use a paintbrush, fine, but I've been
doing so for years and NEVER had a problem. I am not
recommending anything in particular though, there is no
cleaning method that is foolproof but one suggestion you
made to use a damp rag is about the worst thing imaginable,
because it will leave a gross-looking mess everywhere, as if
the board were left out in an alley during a thunderstorm
and debris washed up all over it. If there is enough dust
that it really needs cleaned, a damp rag is just going to
make a huge mess... been there, done that, found a better
way.