What is Electrostatic Discharge?
Who hasn’t experienced the abrupt zap from touching a TV or other appliance after walking across wall-to-wall carpet on a dry winter’s day? We can all relate to this most familiar example of electrostatic discharge (ESD). And while it may be harmless to you, ESD can have some pretty serious effects on electronic parts. ESD is the sudden release of static electrical energy between an object and ground, or anything else that happens to get in between. But before we go any further in this discussion, let’s briefly cover static electricity.
What is Static Electricity?
Static electricity is the build-up of electrical charge on the surface of an object, or more precisely, an imbalance between positive and negative charges on an object. It is brought about by the contact and removal of electrons from one surface against another. This removal doesn’t eliminate electrons but is simply the shifting between surfaces, resulting in a build-up of a negative charge on one of the surfaces. The material that loses electrons becomes positively charged, and the material that gains electrons becomes negatively charged.
The displaced electrons can accumulate on the surface of the receiving object and remain stationary, or “static” until they are released, or discharged. The creation of a static electrical charge is known as triboelectric charging. The amount of this charge is typically expressed as the surface voltage of the material being measured.
The Problems Caused by ESD
The amount of static electric charge that can accumulate on an object is determined by the material from which it is made, the surface area of contact between it and another object or material, the relative humidity, and the speed of object separation. ESD charges can range from a few volts to kilovolts, but discharges of even 100V differences or less may cause problems with sensitive components or systems.
ESD can damage electronic components ranging from simple diodes to complex integrated circuits. Current flow from ESD can literally blow holes through computer chips, cause contact and interface damage, increase heat generation in circuits, leading to thermal damage to nearby components, and cause induction-related device polarization.
Types of ESD Damage
Three types of damage to components can be caused by an ESD event:
- Parametric Failure – affecting the individual performance parameters of a component but not its complete functionality.
- Catastrophic Failure – causing the affected component to completely stop functioning.
- Latent Damage – causing undetected damage that can lead to component degradation and ultimate failure.
ESD Protection Strategies
Damage to electronic components from ESD events can lead to significant expense not just from the component price, but also from repair, re-work, and downtime costs. Fortunately, there are solutions for dealing with ESD that range from the use of simple workplace grounding equipment to complete systems to handle ESD build-up and prevent problems. Our friends at OnLineComponents.com provide a variety of solutions that range from ESD and transient voltage suppressors to static dissipation gear and monitoring devices for both bench and production work. You can visit them and also read about their in-depth take on ESD here: What is Electrostatic Discharge (ESD)?
Summary
ESD and the problems it can cause for sensitive components is a serious issue that will continue to increase due to the growing complexity and miniaturization of modern electronic devices. It can cause problems at all levels of the electronic supply chain. Products, systems, and manufacturing protocols exist to help prevent and mitigate the damage that can be caused by this simple fact of nature.
