Electro-Static Discharge (ESD) is an invisible menace that lurks inside your electronics production areas, including zones dedicated to Research and Development, Manufacturing, Testing and Storage. Very simply, ESD is damage caused to electronic assemblies by high-potential static electricity that collects on the artefacts, including people in the area. As the name suggests, ESD is static i.e. it lacks current flow and remains in place for a long time, until the build-up discharges into another body or device.
ESD has always been around. However, this naturally occurring phenomenon came into broad focus with advent of increasingly miniature and complex electronic components. For a layperson, the common idea of ESD could range from seeing dramatic lightning in a thunderstorm to feeling a small shock when they touch metal after a drive in the car. By contrast, the ESD that we are discussing is invisible and omnipresent, and yet, it can cause widespread havoc in electronic assemblies without any apparent physical manifestation.
ESD can damage and destroy intricate construction of today’s miniature electronic components. Miniaturization packs integrated circuits in smaller spaces while using less semiconductor material and smaller on-chip protective devices. All these factors make modern electronic devices ever more vulnerable to damage by ESD.
ESD Prevention and ESD Protection are vital to improving reliability and reducing defects in today’s electronics manufacturing facility.
Causes of ESD
Static electricity is a result of several processes:
Tribocharging: This phenomenon occurs on separation of insulating materials that were previously in contact. Example of this effect is a person walking with insulating shoes on a rug or brushing dry hair with a plastic brush.
Electrostatic Induction: This induction occurs when an electrically charged object is in proximity with a conductive object that is isolated from the ground. For example, plastic items with charged surfaces can result in ESD on sensitive components.
Result of ESD Damage
ESD causes large currents dissipating through the component, taking the lowest impedance path to ground for equalizing potentials. The current may go through the semiconductor in the integrated circuit, causing local hot spots that damage the junctions and breakdown the structure.
ESD can cause permanent damage to the electronic components, where they stop working completely. This type of damage is relatively easy to segregate during testing, as the product just does not work as intended.
Even worse, ESD can also result in latent damage that weakens the electronic device resulting in intermediate faults or complete failure at a later stage. This type of damage is very difficult to detect during testing and subsequently rectify before dispatch.
Apart from causing varying degrees of inconveniences to the customer, failure of an electronic item in the field results in loss of reputation, warranty costs, replacement costs and legal liabilities. Industry estimate mention 8% to 33% losses as a direct result of ESD damage. Thus, ESD imposes an unacceptably high cost to the bottom-line and addressing the issues is imperative for any professional organization.
The good news is that ESD prevention and control is easy and sustainable.
Here are some common strategies and methods to overcoming ESD in your electronic assembly area:
Planning and Procedures:
Create ESD Protected Area (EPA)
This clearly demarcated area has several ESD protection devices to eliminate any static build-up. For demarcation, the area has clear signage as well as decals.
Implement Access Control
The area has access control ensuring that only trained and properly protected personnel enter this demarcated space. Since people can walk into the EPA with static charge on their bodies, a suitable anti-ESD mat or grounding plate at the access point could help dissipate build-up prior to entry.
ESD protection in EPA’s follow internationally recognized protocols. These protocols take into cognizance the type of electronic product handled in this area and its ability to withstand ESD. Standards such as ANSI/ESD S20.20 and IEC 61340-5-1 explain the ESD protection in EPA’s.