Around 600 B.C., Thales of Miletus discovered a peculiar property of amber. This Greek philosopher, mathematician and astronomer noticed that after rubbing the fossilized resin, straw would be drawn to it. Thales had uncovered, centuries before a modern understanding of electricity, the concept of electrostatic attraction. By rubbing amber, Thales was harnessing the triboelectric effect, creating an electrostatic charge through the contact and separation of two materials. Twenty-four hundred years later, in 1600, English natural philosopher William Gilbert would describe this property in his work De Magnete using the New Latin term “electricus,” based on the Ancient Greek word for amber: elektron.

It would not be well characterized for over two millennia after Thales’ discovery, but static electricity and control over its generation and release has been a significant concern over that period to many industries. From measures to prevent static sparks during the manufacture and storage of gunpowder stockpiles in European forts in the 15th century, to static dissipative methods employed in American paper mills in the 19th century, the discharge of static electricity has been a considerable hazard.

Electrostatic discharge

The rise of the microelectronics industry in recent decades has brought increasing attention to the issue of electrostatic discharge (ESD). ESD – the rapid and spontaneous transfer of electrostatic charge between objects at different electrostatic potentials – can damage an electronic device by, for example, breaking down a junction or melting metal contacts to cause a short circuit. The damage can be either catastrophic, resulting in the immediate failure of the device, or latent, showing up when the device enters service as degraded performance or reduced operating life.

Items vulnerable to ESD, referred to as ESD sensitive (ESDS) items, include a wide range of electrical and electronic components and equipment, from resistors, capacitors and piezoelectric crystals to microchips, printed circuit boards and network equipment. It is essential to protect these items from electrostatic damage at every step of the production process, from prototyping, fabrication and assembly to packaging, testing and inspection. Even low-voltage discharges of less than 10 V can damage sensitive items. Failure to protect items from ESD can result in substantial direct and indirect costs, such as reduced chip yield, increased time-to-market and diminished customer satisfaction.

ESD damage represents a significant threat to electronics. Fortunately, the danger can be mitigated with the proper equipment and procedures. The key to controlling ESD in a workspace is maintaining an equipotential balance between all conductive equipment and workers in an area. This is achieved by establishing an electrical connection between each item in the space and a known ground potential. By linking everything in the area to the same voltage ground potential, ESD is minimized. Equipment that can help achieve this goal includes wrist straps, footwear and garments that conduct excess charge to ground as well as seating, flooring and working surfaces that dissipate static charge before it has a chance to accumulate to a level at which an ESD event might occur.

ESD workbenches

In many technical and manufacturing settings, sensitive electronic items are often handled on workbenches. These fundamental pieces of furniture provide stable, flat working surfaces for personnel to assemble, repair, test or perform other actions on the objects they work with. As workers move around and manipulate electronic items, it is essential to avoid a buildup of static charge to prevent damaging ESD events.

Figure 1: A Formaspace workbench

The ESD threat can be minimized by choosing workbenches made of a material that dissipates static charge and ensuring that the workbenches and the workers linked to the workbenches by wrist straps are connected to ground. ESD workbenches protect sensitive items from ESD by dissipating charge to neutral ground before it has a chance to accumulate.

Workbench manufacturer Formaspace engineers custom and standard ESD workbenches that not only protect against ESD but also improve the efficiency, productivity and ergonomics of assembly, repair and testing tasks for electrical and electronic devices. Formaspace’s ESD workbenches are available with a variety of workspace-enhancing add-ons, including CPU holders, cable management, power strips, height adjustment (manual crank hydraulic or electric hydraulic), upper and lower shelving, cabinets, drawers, louvered panels with storage bins, LED lighting and casters.

Formaspace ESD furniture complies with the premier multi-industry ESD safety standard, ANSI ESD S20.20, ensuring that every Formaspace ESD workbench can be used to safely implement an ESD control program to protect electrical or electronic parts.

ESD workbenches vs. ESD mats

Although ESD workbenches may have a higher upfront price than other anti-ESD options like ESD mats, ESD workbenches offer a number of benefits that make them the superior long-term solution.

First, an ESD mat placed on top of a traditional workbench covers only a portion of the work surface; components accidentally set down off the mat can suffer ESD damage. ESD workbenches eliminate this risk since the entire ESD-protected work surface can be utilized.

Table 1: Comparison of ESD workbenches and ESD mats

Second, despite regular cleaning schedules, dirt, dust and body oils can become embedded in ESD mats, diminishing their ability to dissipate static charge. ESD workbenches, on the other hand, are easily washed and wiped down with an ESD surface cleaner to maintain protective properties.

Third, ESD mats tend to be vulnerable to damage from chemicals such as adhesives and solvents and activities like soldering, cutting and dragging equipment on the mats. Conversely, ESD workbenches have durable, solid surfaces that are resistant to impacts, wear, heat, spills and chemicals.

Although ESD mats might be a cheaper short-term option, their inferior durability may necessitate replacement every year or sooner. At hundreds of dollars per mat, the costs quickly add up. ESD workbenches are a superior permanent solution, with bigger working surface areas, easier cleanup, improved durability and lower long-term costs. All Formaspace workbenches are made in the company’s factory headquarters in Austin, Texas, and have a 12-year warranty.

ESD workbench surface materials

The choice of material comprising the working surface of an ESD workbench is an important consideration. Certain materials are better suited for this application than others. The primary determining factors are the electrical surface and volume resistances of the material.

Table 2: ESD material categories per ESD ADV1.0-2017Insulative materials like ceramic or wood should not be used as ESD workbench surface materials. With high resistances greater than 1 x 10¹¹ ohm, they do not allow electrons to flow freely across their surfaces or through them. Static charge can accumulate on insulative materials, leading to ESD events that damage electronics.

Conductive materials like steel or aluminum, with resistances less than 1 x 10⁴ ohm, permit the free and easy flow of electrons, readily conducting static charges to ground. They are not, however, ideal ESD workbench surface materials. This is because the rate at which conductive materials dissipate a charge is so rapid that the magnitude of the current can damage sensitive items.

The material best suited for ESD workbench surfaces is a static dissipative material that balances the two extremes of insulators and conductors. With resistances between 1 x 10⁵ ohm and 1 x 10¹⁰ ohm, static dissipative materials allow electrons to flow across and through them, but they do so at a more measured rate. Charge transfer through a static dissipative material will occur more slowly than through a conductive material. This restrained rate protects electronics from rapid discharges.

Formaspace ESD workbenches are available with a variety of static dissipative work surface materials, including high pressure laminate (HPL), dual HPL and ESD powder-coated surfaces. HPL is formed by pressing together layers of resin-impregnated paper under high pressure. Dual HPL surfaces feature a dissipative layer on top of a carbon layer that is compatible with continuous ESD monitoring systems. ESD powder-coated steel surfaces take advantage of the structural strength of steel while tempering its conductive properties with a static dissipative coating to shield electronics from rapid ESD events.

A wide range of standard ESD workbenches are available for purchase from Formaspace. The company also works with clients to develop custom furniture solutions tailored to specific applications and environments. These customized solutions take into account the unique problems and objectives of each client. The result is furniture that integrates seamlessly into client processes to improve workflow efficiency and boost worker productivity.

Custom ESD furniture solution

In many cases, Formaspace’s custom ESD furniture solutions not only optimize productivity, but also reduce client expenses. In 2015, a major American computer manufacturer decided to move its global labs back to one location, co-locating them in Austin. The move was projected to cost $100 million but executives wanted the relocation completed for much less.

Formaspace worked with the company to develop a furniture solution to securely support heavy, expensive research and development servers within an easily accessible, compact space while protecting them against damage from ESD. The solution includes a custom condo rack, moving shelf bench and height-adjustable ESD workstation.

Figure 2: Custom Formaspace ESD workbench solution

The condo rack consists of four vertically stacked pullout shelves that can each support one of the company’s expensive 5U R&D servers. Each shelf can be secured in extended or retracted position by lock-in, lock-out slides and locking tabs, and is equipped with detachable sides, adding an extra layer of protection to prevent servers from slipping off the edge.

The moving shelf bench features an upper shelf where two oscilloscopes are stored. The height of the shelf is manually adjustable so that the instruments can be lowered or raised out of the way as needed for server tests.

The third piece of furniture, the ESD workstation, is equipped with two upper shelves and a pair of 7Flex monitor mounting arms that allow two displays to be positioned at any angle. The entire sit-to-stand workstation is raised and lowered with an electric-hydraulic height adjustability system. The workstation hosts a specially developed, 24/7/365, ESD testing and monitoring solution that largely automates the monitoring of a server testing process, which can last up to 36 hours.

With Formaspace’s assistance, the computer manufacturer was able to limit the cost of construction to $16 million, with under $1 million in furniture costs, saving $84 million compared to the original $100 million projection. Formaspace’s innovative furniture solutions achieved these significant savings. As a result of the space-saving condo rack design, which reduced floor space usage by 37%, a new building was not needed to house the additional co-located equipment. The rack also improved productivity by allowing technicians to simultaneously test four servers, a big throughput improvement compared to the old one-at-a-time setup. Furthermore, the automated ESD monitoring solution eliminated the need for constant manual supervision, saving millions in labor costs annually. Formaspace’s custom ESD rack and workbenches guaranteed the expensive servers would not suffer ESD failure, eliminating the need to purchase ESD mats worth several hundred thousands of dollars per year.

3DConfigure Virtual Workbench Builder

Formaspace excels in delivering custom-engineered ESD workbench solutions tailored specifically to unique client applications. The company also offers a unique online tool that lets users visualize the workbench in real time as they design it. The 3DConfigure Virtual Workbench Builder is a point-and-click graphical interface based on WebGL, a JavaScript API that allows native rendering of graphics within a web browser without requiring a plugin.

Figure 3: Formaspace's 3DConfigure Virtual Workbench Builder

Customers can zoom, pan, rotate and even change the angle at which the virtual light shines on the workbench as they choose the workbench size, configuration and accessories according to their needs. Customizable choices include load capacity, work surface dimensions, adjustable-height options, workbench feet, work surface material, storage elements (shelves, drawers, cubbies or cabinets), lighting and other accessories that improve accessibility and productivity like computer monitor mounts, power strips, peg or cork boards, or wire management.

When the design is finalized, it can be submitted for same-business-day pricing quotes, with the final product ready to ship in three to four weeks.

Design an ESD workbench from the comfort of a computer or mobile device using the 3DConfigure Virtual Workbench Builder, or contact a Formaspace Design Consultant for assistance in developing a custom ESD workbench solution tailored to specific requirements.