Introduction to Causes and Effect of Electrostatic Discharge
This article is a continuation of the previous Basic Static Electricity and Electrostatic Discharge article. This time we will outline a brief analysis of what of the common root causes analysis, effect, impact or danger of electrostatic discharge (ESD) on various sectors —Omazaki Consulant is an ESD consultant that provides static electricity and electrostatic discharge consulting services. Contact us by sending an email to firstname.lastname@example.org or by filling in the form in contact.
This article is a series of several related articles:
- Static electricity and Electrostatic Discharge (ESD) – Basic
- Causes and Effect of Electrostatic Discharge
- Solutions, Prevention and Control of Electrostatic Discharge
Causes of Electrostatic Discharge
Electrostatic discharge has been around since the beginning of time. However, this natural phenomenon has only become an issue with the widespread use of solid-state electronics.
Electrostatic discharge or ESD occurs when two objects with different voltage potentials meet so that there is a transfer of charge from one object to another until the same potential occurs. The time required for it varies depending on the characteristics, for example the amount of capacitance and resistance between them,
The magnitude of electric charge produced by triboelectric charging depends on many factors, namely the contact area, the nature of the material, how quickly the materials are separated, and the relative humidity. In addition to triboelectric charging, other less common sources of static electricity include induction, ion bombardment, and contact with other charged objects.
Danger and Effects of Electrostatic Discharge
Most common effect or danger of electrostatic discharge are fire and explosion and electronic fail. Disruptions and damages have been reported over recent years, but in most cases, root causes of the ESD failures cannot be traced. ESD malfunctions and damages are generally classified as unknown electric failures.
Electrostatic shock to people is also a real and ever-present risk. ESD energy can be high enough to cause painful sensations to human, resulting in involuntary movements and can lead to accidents.
Fire and Explosions
A key area of danger is static electricity in the presence of flammable gases, liquids and other flammable materials. The use of flammable substances in facilities has decreased, but without the control, the risk of fires and explosions can still occur, especially in laboratories, intensive care units, and operating rooms.
ESD damage to electronic components can be:
- Soft Failures
- Latent Defects
- Catastrophic Failures
The electric current due to ESD can alter the internal logic, causing the system to lock up or behave abnormally and unexpectedly. ESD can cause data flow corruption in electronic systems. Although the effect is temporary, electrostatic discharge events can slow down communications or require a system reboot in the event of a lockout.
Latent defects, meaning degraded or wounded components. Latent failure is the less noticeable type. It’s where the device has been damaged but does not fail immediately. Because the damage is not readily apparent, subsequent damage can continue to occur before failure results. Since the device is partially degraded, failure can occur at a later time—even years later.
The discharge of static electricity near active electronic systems can cause memory corruption or temporary failure owing to device latch-up, usually recoverable on re-start. At the device level, however, electrostatic discharges may result in total destruction. The mechanisms of such failure are discussed.
Catastrophic failure causes a failure in an ESD sensitive item that is permanent. The ESD event may have caused a metal melt, junction breakdown or oxide failure. Normal inspection is able to detect a catastrophic failure.
Direct catastrophic failures, meaning completely failed or dead components.
A catastrophic failure of an electronic component can be the least costly type of ESD damage as it may be detected and repaired at an early manufacturing stage.
What Causes Electronic Devices to Fail?
ESD damage is usually caused by one of three events: direct ESD to the device, ESD from the device, or field-induced discharges. Whether or not damage occurs to an ESD sensitive or susceptible item (ESDS) by an ESD event is determined by the device’s ability to dissipate the energy of the discharge or withstand the voltage levels involved. The level at which a device fails is known as the device’s ESD sensitivity or ESD susceptibility.
Discharge to the Device
An electrostatic charging (ESD) event can occur when any charged conductor (including the human body) discharges to an item. A cause of electrostatic damage could be the direct transfer of electrostatic charge from the human body or a charged material to the ESDS. When a person walks across a floor, an electrostatic charge accumulates on their body. Simple contact (or proximity) of a finger to the leads of an ESDS or assembly, which is typically at a different electrical potential, can allow the body to discharge and possibly cause ESD damage to the ESDS. The model used to simulate this event is the human body model (HBM). A similar discharge can occur from a charged conductive object, such as a metallic tool or fixture. From the nature of the discharge, the model used to describe this event is known as the machine model (MM).
Discharge from the Device
The transfer of charge from an ESDS to a conductor is also an ESD event. Static charge may accumulate on the ESDS itself through handling or contact and separation with packaging materials, worksurfaces, or machine surfaces. This frequently occurs when a device moves across a surface or vibrates in a package. The model used to simulate the transfer of charge from an ESDS is referred to as the charged device model (CDM). The capacitances, energies, and current waveforms involved are different from those of a discharge to the ESDS, likely resulting in different failure modes.
Another electrostatic charging process that can directly or indirectly damage devices is termed field induction. As noted earlier, whenever any object becomes electrostatically charged, there is an electrostatic field associated with that charge. If an ESDS is placed in the electrostatic field and grounded while located within the electrostatic field, a transfer of charge from the device occurs as a CDM event. If the item is removed from the region of the electrostatic field and grounded again, a second CDM event will occur as the charge (of opposite polarity from the first event) is transferred from the device.
Contact Omazaki Consultant if you are looking for static electricity and electrostatic discharge (ESD) analysis study, measurement, and assessment consultants at your business facility in Indonesia.
- EOS/ESD Association, Inc.
- Fundamental of ESD – A Primer on Electro-Static Discharge, Teledyne Advanced Pollution Instrumentation
- ESD Training – Bondline – UK
- Basic Concepts in ElectroStatic Discharge – SCS
- Guide ESD Protection – Tridonic
- The Prevention and Control of Electrostatic Discharge– Mini Circuit
- Electrostatic Discharge – Wikipedia
- Electrostatic Discharge: Causes, Effects, and Solutions – EC&M
- DESCO Industries ESD Awareness Booklet
- Study and Assessment of Power Quality
- Static electricity and Electrostatic Discharge – Basic
- Electrostatic Discharge Solutions, Prevention and Control