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. Your hand

2. Glass

3. your hair

4. Nylon

5. Wool

6. 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

• 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.

• All ESD equipment should have a resistance of 1Ω in the leads.

• 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 air or an object without cables if lightning hits the highest object why do old sailing tall ships never get hit at sea? Multiple points (i.e. masts & spires ) reduce the chances of one 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.

• Positive uses of static electricity are:-

• Laser Printer• Sticking up

Balloons

Any Questions ?