Causes and Types of Electrostatic Discharge
– Static electricity generated through tribocharging (walking on a rug, rubbing a plastic comb against dry hair, etc.)
– Breaking contact between two materials results in tribocharging
– ESD damage can also occur through electrostatic induction
– Spark is the most spectacular form of ESD
– ESD events can occur without a visible or audible spark
– Cable discharge events (CDEs) occur when connecting electrical cables to a device
– Energetic charged particles can also cause ESD
Sparks and their Effects
– Sparks are triggered when the electric field strength exceeds the dielectric field strength of air
– Sparks can form in air during electrostatic discharges from charged objects
– Electrostatic discharge in the atmosphere can result in the formation of ozone and nitrogen oxides
– Sparks can be an ignition source in combustible environments, leading to explosions
Damage Prevention in Electronics
– Many electronic components, especially integrated circuits and microchips, can be damaged by ESD
– Grounding is important for effective ESD control
– Electrostatic Discharge Protected Areas (EPAs) are used in manufacturing to prevent ESD
– International standards define the requirements for an EPA, including the use of ESD-safe packing material, conductive garments, wrist straps, etc.
Protection during Manufacturing and Transit
– ESD prevention in manufacturing is based on the concept of an EPA
– EPA ensures that there are no highly-charging materials near ESD sensitive electronics
– Packaging materials should be designed to minimize rubbing together during shipping to prevent static buildup
– Surface resistance and volume resistivity of packaging materials should be controlled to minimize static buildup and discharge
Simulation, Testing, and References
– ESD Simulator with a human body model (HBM) is used to test the susceptibility of electronic devices to ESD
– Other standards include MIL-STD-883 Method 3015 and the ESD Associations ESD STM5.1
– Charged device model (CDM) test is used to define the ESD a device can withstand
– References to organizations and resources related to ESD prevention and testing Source: https://en.wikipedia.org/wiki/Electrostatic_discharge
Electrostatic discharge (ESD) is a sudden and momentary flow of electric current between two differently-charged objects when brought close together or when the dielectric between them breaks down, often creating a visible spark associated with the static electricity between the objects.
ESD can create spectacular electric sparks (lightning, with the accompanying sound of thunder, is an example of a large-scale ESD event), but also less dramatic forms which may be neither seen nor heard, yet still be large enough to cause damage to sensitive electronic devices. Electric sparks require a field strength above approximately 4 × 106 V/m in air, as notably occurs in lightning strikes. Other forms of ESD include corona discharge from sharp electrodes, brush discharge from blunt electrodes, etc.
ESD can cause harmful effects of importance in industry, including explosions in gas, fuel vapor and coal dust, as well as failure of solid state electronics components such as integrated circuits. These can suffer permanent damage when subjected to high voltages. Electronics manufacturers therefore establish electrostatic protective areas free of static, using measures to prevent charging, such as avoiding highly charging materials and measures to remove static such as grounding human workers, providing antistatic devices, and controlling humidity.
ESD simulators may be used to test electronic devices, for example with a human body model or a charged device model.
