Electro Static Discharge
Complex logistics, intricate local market demands and quick response and turnaround times are just some of the issues TSC have to navigate in order to deliver industry-best repair and logistics solutions to clients around the world.
The natural occurring phenomenon of Electro Static Discharge (ESD) is another fundamental business challenge, one with costly implications to both TSC and to our customers. ESD is the discharge of static electricity from one material or object to another, sometimes creating a visible spark.
People discharge frequently, the spark going largely unnoticed unless the voltage reaches 2,000 to 3,000 volts, with a visible discharge occurring at around 7,500 volts. There are many factors that affect the size of a charge, from type of materials subjected to contact or separation, to the amount of friction over time, as well as the relative levels of humidity in the surrounding environment.
While ESD is responsible for large scale events like lightning and considered a root cause for some industrial accidents (the famous downing of the Hindenburg zeppelin for example, was determined to be caused by ESD when it touched against the mooring tower on landing, causing the zeppelin ‘skin’ to catch on fire), it is the often unseen and unheard forms of ESD that pose particular risk to TSC and the industry as a whole, causing significant and costly damage to sensitive electronic devices. See Real life ESD example at a gas station.
The Cost of ESD Damage
Electronic equipment or device failures due to ESD damage are categorized into two types – Catastrophic and Latent.
When the heat from ESD visibly melts or welds components and immediately destroys them it is known as a catastrophic failure. Though this type of event leads to high repair costs and customer DOA’s (products ‘dead on arrival’), the benefit is that they are at least identifiable by inspection which results in timely resolution for the customer.
A Latent failure occurs when an ESD current only partially degrades components instead of outright destroying them, causing issues to surface later in the product’s life cycle. This type of failure lowers performance and shortens time between repairs, reducing overall product lifespan. Because Latent failures are not visible they are easily missed, with devices passing testing and then failing some months or years later.
While both types lead to additional costs for repair, Latent failures are considered the more detrimental of the two due to greatly increased warranty and replacement costs, and possible decrease in customer satisfaction levels in the long term. And because they are hard to identify and therefore hard to track, it is imperative to have processes in place to reduce the number of occurrences of Latent failures in the workplace. With industry experts citing static related product losses in the range of 8-33%, translating to billions of dollars annually*, the importance of mitigating ESD in the workplace cannot be underestimated.
Reducing the Effects of ESD
Though eliminating the presence of ESD from any site completely is unlikely, adopting an ESD standard is the best way to reduce its effects on the business.
All conductors in the environment including personnel, should be bonded or electrically connected and attached to a known ground or contrived ground (as on shipboard or on aircraft). This attachment creates an equipotential balance between all items and personnel. Electrostatic protection can be maintained at a potential above a “zero” voltage ground potential as long as all items in the system are at the same potential. This prevents the storage of voltages within the EPA (ESD Protected Area), allowing static electricity to flow safely away.
Different grades of ESD protection are also needed depending on the work performed:
A normal repair operation working with common Print Circuit Boards (PCB) would have enough protection when materials are connected to ground, as shown in the picture above.
TSC Tape Backup Unit (TBU) repair operation requires additional ionizers as certain materials are very sensitive to ESD charges above 5 Volts.
Manufacturing clean rooms have ionized air flow build in and will go even further with strict humidity controls and dust particle control. (No ESD exceptions allowed)
Also without real contact an electrostatic field can cause ESD damage by induction/polarization. Isolating material (non-conductive) should be removed from the operation as much as possible as these have the potential risk to accumulate electrostatic charge.
A Way of Life
At TSC we follow the ESD standard rigidly, taking corrective action based on periodic measurements and the specific requirements of each workplace. Stringent guidelines are in place globally to ensure that our operations are at minimal risk, reducing product and repair costs and the associated impact to client satisfaction.
Preventing or working with ESD should be second nature, or as Bas Grootemaat, Chairman of the Dutch National Electronic Committee (and former TSC Europe employee) would say, “It’s a way of life.” It’s one of the tenets we adhere to at TSC; a fundamental part of our business that ensures the delivery of exceptional products and services to our customers.
For questions regarding ESD and ways to reduce risk, please contact Bart Derks, TSC Europe at phone number: +31 6 53180027 / email: BartDerks@sprague-europe.com
* Data from www.esda.org