As we discussed in a companion article on this subject, ESD is the rapid release of a static electricity charge from one object to another object on its path to ground. This discharge of electrical force can cause significant damage to electronic components that may affect their performance, or lead to complete device failure. The sensitivity of the receiving object and the amount of electrical discharge will determine the extent of damage done.

There are strategies and products that address ESD-safe handling of components throughout the supply chain, from production, storage, shipping, insertion and onto testing and repair. Any discussion of avoiding the problems that can arise when you introduce an ESD event to electronic components should approach the subject from a component level, a board level, and an environment level. In this article we’ll discuss each, but it is wise to remember that, as a force of nature, ESD can be managed but total elimination is difficult.

Establishing an ESD Strategy

Regardless of the size of your operation, from bench circuit design to final manufacturing, ESD prevention should be a common theme. This starts with understanding your need for protection via a risk assessment, creating a plan to meet your needs, choosing ESD prevention devices or systems that are appropriate, establishing an ESD-free work zone, and planning to make your solution an ongoing and required protocol.

In your work to rein-in ESD damage from your work environment, whether big or small, you may also find guidance by referring to the ANSI/ESD S20.20-2021 standard, Protection of Electrical and Electronic Parts, Assemblies and Equipment, which outlines potential ESD risk and mitigation strategies.

Component Factors

Many modern electronic components have an inherent level of tolerance to ESD or other surge events. This is another way of saying that some components are more susceptible than others. The materials used to manufacture a component can serve to provide protection, so it may be a good idea to bring up the subject with your component supplier early in the game. The engineering professionals at an authorized component distributor, like OnlineComponents.com, can be of significant assistance.

At the design stage, simple selection of ruggedized components with ESD resistance can prevent problems later on. But while the elimination or replacement of devices that are overly sensitive may sound like a simple solution, it can also serve to increase overall system cost or eventual product price beyond acceptable levels for your budget.

Board Factors

Once you have identified and addressed the ESD-vulnerable components in your design, the next step may be the concurrent design of a built-in ESD protection circuit in the system for safety of the components that cannot be replaced. These circuits use devices such as reverse bias diodes, varistors, transient voltage suppression diodes, or fuses to shunt energy to a ground network, or absorb energy through a resettable or consumable device before damage occurs.

It is worth noting that ESD pulses are extremely fast, with rise times in the low nanosecond range. Any components employed in a protection circuit need to offer sufficiently fast response times to react to these discharges. ESD suppression components, like multilayer varistors and polymer-based suppressors, can also act to reduce ESD voltages to acceptable limits.

While a board-level protection circuit can be useful, it is important to remember that it will only function during the operation of your design post-manufacture, and it can add significant production costs to your product. Additionally, you will still need to deal with the problems that may arise during production, testing, shipping and repair/rework of the product, or, what we refer to as the environmental factors.

Environmental Factors

Under this category, we are including those influences outside of component selection and circuit design that can have an impact on ESD problems. Environmental factors cover the largest influences on electrostatic build-up, and discharge. Mitigation or prevention of these influences can range from simple to complex solutions, depending on your need.

These factors include low humidity levels in the production or use facility, ability to deal with wayward static charges prior to possible discharge, speed of separation between objects during manufacturing, staff-induced static build-up, shielding of sensitive components or boards from ESD during transit, and static charge accumulation on objects other than components, including people.

The list of available products, materials, systems, and equipment directly related to ESD prevention from the workbench to the factory floor is extensive, and selecting what you need can be challenging. Here is a quick list of some of the solutions you may want to consider:

• Conductive bubble wrap, plastic bags, and containers for transport, storage and shipping
• Shielded boxes, foam sheets, and tape (plus dispensers) for shipping
• Grounding mats, wrist straps and cords that shunt static to ground for workspaces
• Compliant desks and workstations for assembly operations
• ESD-resistant clothing, shoes and gloves for technicians or field personnel
• Ionizers for room-size ESD control
• Ionization air guns and blowers to remove static charges from surfaces or components
• Static resistant or conductive floor tiles, carpets and mats to resist or manage static build-up across the work area
• Chemicals and treatments for surface cleaning to reduce static production
• Conductive paints and coatings to prevent harmful static build-up
• Monitors and testers to assess ESD threats

And the list goes on. It may go without saying that if you have a specific need to prevent static build-up or ESD events, no matter how large or small, a solution exists. Most ESD management efforts are customized to individual needs, which is another opportunity for you to take advantage of the product knowledge base at your authorized component distributor.

A Word About ESD Protocols

Any ESD prevention or mitigation system will be of limited protective value unless all of its individual components, from wrist straps to shielding products are put to use continuously in areas where sensitive components reside. A wrist strap will do no good if it is not plugged into a grounding network. As with virus protocols in the public health realm, ESD efforts cannot be implemented and forgotten. All it takes is one spark.

Summary

Electrostatic accumulation and its sudden discharge are not new phenomena, but the negative effect they can have on electronic components and systems continues to grow as products become more complicated and miniaturized. Understanding the implications and effects of ESD throughout the supply chain, and continuously working to implement ESD product use along with production protocols can keep any shocking results to a minimum.