About Static Charg

What is static charge?

Have you had an experience your skirt clung to you?
Haven't you feel an electric shock when you opened the car or hotel door?
Are you bothered about crackling sound when you take off your sweater?

All these are tricks of static charge. If opposed polarity charge is generated on the wears, they are pulled each other, but if same polarity charge exist on the wears, they are pushed. This is the reason of clinging.

If electro-static discharge (ESD) occurs when static charge moves to the other object, electrical shock, crackling sound or spark is detected. The biggest natural ESD is lightning. Though not as big as lightning, ESD does unknown mischief.

Isn't your PC or other electronic instrument frozen by the unknown reason? Most of the reasons are ESDs. It may not cause terrible problems though you start it again if you are enjoying hobby, but it will cause big problem if you are handling very important or large volume information.

How is static charge generated?


In general, the friction between isolators or isolator and metal generates static charge. If metal is not grounded, it will be charged as well (This is true in the following cases).


This is similar to above triboelectricity. When a thin sheet is peeled off the insulated portion of the electronics devices, static charge is generated. This does not naturally occur very often, but does occur often in the production line of the electronics equipments, and may cause big damages. To remove a protection sheet from LCD display is one of the typical example.

Field induced charging

Static charge is generated though two objects are not contacted as above. If a charged object moves to/from other object, static charge of the other object will be charged. This is called as a field induced charging. The moving charged thundercloud charges neighboring clouds because of field induced charging.

Damage examples of ESD

It is almost true to think that unknown reasons of the electronic equipment failures are because of ESD. But in the production lines of the components used in these electronic equipments, yield decreases by degradation or damage by ESD and field failure rate of these components is increasing.