aluminium foil

  • Thread starter Thread starter annalissa
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annalissa said:
Hi all,

why is it said that never place a motherboard on a sheet of aluminium
foil ?
Click to expand...

Electronics are sensitive to electrostatic discharge (static electricity).

In an electronics lab, the staff take precautions against static. This
can include an antistatic flooring material, antistatic mats on
benchtops, antistatic wrist strap to connect the staff member
electrically to the bench, and so on.

Each of the antistatic precautions is "partially conducting".
That means, if you were to take an ohmmeter, and try to measure
the resistance of the antistatic material, it conducts electricity,
but not very well.

The same would be true of a wrist strap. The wrist strap has a
series resistor in line with it, of perhaps 1 megohm (one million
ohms).

The purpose of these resistances, is to limit the flow of current
during a static discharge event. Static is to be removed slowly,
rather than in one huge jolt. So in a properly protected lab,
you should never hear a "snap" as a static electric spark
jumps from someone in the lab, to the equipment they're working
on. The antistatic precautions should remove the charge slowly,
without making a sound.

Tin foil is a very good conductor. If you walked up to a
motherboard, which was grounded underneath by tin or
aluminum foil. the peak current flow could damage the electronics.

A second reason for not using foil underneath, is because you
could short remaining power storage devices. For example, the CMOS
battery socket may have contacts protruding from the bottom of
the motherboard. While it isn't likely to happen, you could
reduce the life of the CMOS battery, by draining current from
it.

HTH,
Paul
 
annalissa said:
Hi all,

why is it said that never place a motherboard on a sheet of aluminium
foil ?
Click to expand...
The foil goes around your head.
Its to keep the the FBI brain police out. :)
 
annalissa said:
why is it said that never place a motherboard on a sheet of aluminium foil ?
Click to expand...

The main reason: the foil could short out the lithium battery and
cause an explosion.

Another reason: the mobo could be zapped by static electricity
because foil conducts so well that it allows high current to flow.
That's not a problem if the foil makes first contact with the ground
of the mobo (metal shells of the connectors on back) but risky
otherwise. The pink anti-static foam sheet or bubble wrap or a metal-
plated plastic bag is much safer to use because they conduct much
less. With those bags, be sure that only the inside of the bag
touches the mobo because not all such bags are anti-static on the
outside (they're "metal in" only, not also "metal out").
 
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