Transcript ESD What is it and How do we deal with it

ESD What is it and How do
we deal with it
Background lightening
Static Electricity
Why is Static Electricity
important?
• Static Electricity is a concern when handling computer
components. With a build up of static in an area it could
cause a discharge and cause damage. A static charge of
only 200 volts is sufficient to damage a computer
component. A static charge of 2000 volts is enough for a
person to notice. This may have been experienced when
walking across a room and touching a metal surface.
Static charges can build up in the body just by walking
across the room. It may not be apparent, but it is usually
enough to damage computer components if they were to
be touched.
What causes Static Electricity &
why
• Everything is made from atoms.
These are in turn broken down
into Protons Neutrons Electrons
and Nucleus. Protons have
"positive" (+) charge. Electrons
have a "negative" (-) charge.
Neutrons have no charge, they
are neutral.
Static electricity is the imbalance
of positive and negative charges.
• When we rub two different materials
together, which becomes positively
charged and which becomes negative?
• Scientists have ranked materials in order
of their ability to hold or give up electrons.
This ranking is called the triboelectric
series. The one higher on this list should
give up electrons and become positively
charged
TRIBOELECTRIC SERIES
1.
2.
3.
4.
5.
6.
Your hand
Glass
your hair
Nylon
Wool
Fur
7. silk
8. Paper
9. Cotton
10. hard rubber
11. Polyester
12. polyvinylchloride plastic
This ranking is called the triboelectric series. The one higher on this list
should give up electrons and become positively charged
• When we charge something with static
electricity, no electrons are made or
destroyed. No new protons appear or
disappear. Electrons are just moved from one
place to another. The ESD is the Electrons
moving from a non-conductive material to
replace the lack of Electrons in another area
or conductive material to equalise the
voltage. Electricity is like water constantly
flowing to the maintain an equal level, if one
bit is raised it will flow back to the original
level or try to get back sometimes it needs to
wait until there is sufficient pressure to jump
to the conductive material to get back
Electricity is like Water
• Water always try to get to the lowest point
and it will try an path to achieve this
• Electricity is trying to return to earth
• If there is too much water in a bucket it will
overflow
• If the electrical charge builds up too much
it will discharge through the air Lightening
How can we deal with Static
Electricity & why this works
• The damage with ESD is the sudden discharge
not only because the high voltage but because it
will jump to the nearest conductor. So to control
this we set up a conductive path for any
electricity to flow to earth (as this is the level that
all electrons try to achieve), if we use a good
conductor the flow of a high voltage would still
be sufficient to damage any components so to
reduce this we must increase the resistance of
the conductor so it flows away not floods away.
Anti-static Equipment Flow
Damage is caused by sudden electrons
flooding from the highly charged point
Anti-Static equipment just
allows the Electrons to move
slowly to earth therefore no
damage caused
ESD equipment
• All ESD equipment should have a resistance of 1Ω in
the leads.
• Object of ESD is to get
every surface able to
drain static electricity to a
ground point. The human
element should also
attach to this point to
allow any build up to
drain so that all items are
equal.
• Each object should be linked
to a main point not daisy
chained to each other, as this
could increase the potential
between each end and
becomes dangerous to the
user or equipment. Any ESD
equipment is better than none
this crocodile clips are used
for field engineer where no
ground point exist
What Environment Effects have
on ESD
• The more conductive an environment is the less chance
of an electro static build up like with humidity water
vapour will help conduct any build up.
• Humidity is also related to temperature so keeping it
warm helps the humidity, and also why on cold and dry
more static shocks occur or effects of static attraction are
more common.
Other Static Facts
• How can you remove static from the
• Positive uses of
air or an object without cables if
static electricity
lightning hits the highest object why do
are:old sailing tall ships never get hit at
• Laser Printer
sea? Multiple points (i.e. masts &
• Sticking up
spires ) reduce the chances of one
Balloons
bolt discharge. Like if your hair is flying
away as you bring a hair brush
towards it, it falls back down as the
multiple points do not give a clear path
to discharge to.
Any Questions ?