Static electricity is an imbalance in the amount of positive and negative charges found with in the surface of an object. The sudden flow of static electricity or Electrostatic discharge (ESD) can interfere with the operation of electronic circuits especially the circuits using CMOS and Microprocessor devices.
Static Electricity Precautions
Static electricity in an imbalance in the amount of positive and negative charges with in the surface of an object. There is strong e-field around these charges whether the charges are moving or still.’ Contact induced charge separation’ causes instant static discharges in the form of unnoticed sparks. Static electricity is most often noticed in dry climates and especially in centrally heated buildings and near photocopy machines.
The sudden flow of static electricity or Electrostatic discharge (ESD) can interfere with the operation of electronic circuits especially the circuits using CMOS and Microprocessor devices. ESD produces very high current waveforms and fast magnetic (H-field) or electrostatic field (E-field) disturbances. These can induce very high voltage or current in nearby sensitive circuitry and corrupt data or even cause spurious breakdown. Such things happen if a flash drive or an input device is plugged into the USB when there is high static charge in the body.
The “Tribocharging” poses a constant danger to electronic devices, especially when handling CMOS semiconductors. This also can cause catastrophic effect when one device is plugged into another such as the use of USB to connect peripherals to PC. Static electricity may be very high in low humid environments such as air conditioned rooms. Usually negative charge accumulates near the floor while positive charge accumulates 1 meter above the ground. The static charge can be removed by grounding the body or allowing air flow in the room.
Static Electricity Precautions
1 Be cautious when working around or with electronics during the dry months of the year. Discharge yourself often, and think before you touch a static sensitive device. Static electricity may be free, but it can be costly.
2. When working with any electronic equipment it is best to be sure you are totally discharged by touching something that is metal.
3. Before handling electronic components, it’s important to realise that semiconductors can be damaged by high voltage “static electricity” carried on your body.
4. Integrated circuits and transistors have several connections. If all of these connections are at the same voltage, there is no potential difference across them and no damage will result. However, if just one of the connections sees a different voltage from the rest, damage may occur. Protect them by connecting all of the pins together or wrap them in aluminium foil.
5. Increase humidity. Static effect is increased in environments of low humidity. Buildings using air-conditioning, high levels of heating, or those with a lot of insulation can have low humidity. Increase the airflow into the room. It will remove static electricity.
6. When working with sensitive electrical components or volatile materials (such as papers/powders/flammable liquids) sparks and electrical discharge can cause catastrophic failure in sensitive electrical components and ignite volatile substances. Take steps to eliminate them:
ESD is a serious issue in solid state electronics, such as integrated circuits. Integrated circuits are made from semiconductor materials such as silicon and insulating materials such as silicon dioxide. Either of these materials can suffer permanent damage when subjected to high voltages, as a result there are now a number of antistatic devices that help prevent static build up
Causes of ESD
One of the causes of ESD events is static electricity. Static electricity is often generated through Tribocharging, the separation of electric charges that occurs when two materials are brought into contact and then separated.Friction between two materials results in Tribocharging, thus creating a difference of electrical potential that can lead to an ESD event.
Another cause of ESD damage is through “Electrostatic induction”. This occurs when an electrically charged object is placed near a conductive object isolated from ground. The presence of the charged object creates an electrostatic field that causes electrical charges on the surface of the other object to redistribute. Even though the net electrostatic charge of the object has not changed, it now has regions of excess positive and negative charges.
An ESD spark is triggered when the electric field strength exceeds approximately 10 – 30 kV/cm (the dielectric field strength of air). This may cause a very rapid increase in the number of free electrons and ions in the air, temporarily causing the air to abruptly become an electrical conductor in a process called dielectric breakdown.
ESD Damage due to charge potentials
Nonconductive objects can be damaging charge carriers even without any sparking or obvious effect. This occurs due to the formation of very small static electricity charge potentials when nonconductor come into contact with each other and then separate.
Lightning strike – The natural ESD
The best known example of a natural spark is a lightning strike. In this case the potential difference between a cloud and ground, or between two clouds, is typically hundreds of millions of volts. The resulting current that flows through the ionized air causes an explosive release of energy. During an electrostatic discharge, the intervening atmosphere becomes electrically overstressed. The diatomic oxygen molecules are split, and then recombine to form ozone (O3), which is unstable, or reacts with metals and organic matter. If the electrical stress is high enough, nitrogen oxides can form.