Most ESD problems are not caused by the mat. They are caused by the path from the mat to earth, the wrist strap that is worn over a sleeve, or the chair that isolates the operator from the floor. A workbench is only as good as its weakest connection.
Key takeaways
- Surface resistance should be in the dissipative range, typically 1×10⁶ to 1×10⁹ Ω.
- The ground path must be continuous from the surface, the wrist strap point and the frame.
- Measure resistance under load, not only with a simple meter.
- Seating and footwear are part of the system.
Surface and frame
The work surface is usually a laminate with a conductive layer or a dissipative mat. The surface resistance should be measured at several points, because a mat can be damaged or contaminated in one area. The frame should be powder-coated steel or aluminium, with a dedicated earth terminal.
The surface should be flat and rigid. A thin mat on a wooden table may meet the resistance specification but will not provide a stable work surface for fixtures or torque tools. For assembly, use a bench with a steel frame and a replaceable top.
Grounding path
Each workbench needs a ground terminal connected to the building earth or the EPA earth bus. The surface, the wrist strap point and the frame should all connect to that terminal. Use a star connection, not a daisy chain, so that one loose connection does not disconnect the whole bench.
The wrist strap should have a built-in resistor, typically 1 MΩ, to protect the operator. The cord should be long enough to allow movement but not so long that it drags. The wrist strap should be tested at the start of every shift.
| Item | Typical requirement | Test |
|---|---|---|
| Work surface | 1×10⁶–1×10⁹ Ω | Surface resistance meter, 5 points |
| Wrist strap | 0.8–1.2 MΩ | Wrist strap tester, daily |
| Ground terminal | <1 Ω to earth | Earth resistance test |
| Frame | Connected to terminal | Continuity test |
| Chair | Dissipative, grounded | Resistance to ground |
Configuration for the task
The bench height should suit the work: 750 mm for standing, 720 mm for seated precision work, with an adjustable option if operators rotate. The depth should be enough for the fixture, the parts and the tools, usually 750–900 mm.
Add a shelf for instruments at eye level, a bin rail for parts, and a tool balancer if the tools are heavy. For test benches, provide a cable route and a power strip with a master switch. Keep the power cables away from the ESD ground path to avoid noise.
Acceptance tests
Before accepting an ESD bench, measure the surface resistance at five points, the wrist strap resistance, the continuity from the surface to the earth terminal, and the resistance from the terminal to the building earth. Record the results with the bench ID and the date.
Repeat the tests after any modification, after moving the bench, and at the interval defined in your ESD control plan. A bench that passes at installation can fail after a year of cleaning with the wrong solvent.
Cleaning and maintenance
Use a cleaner recommended by the surface manufacturer. Solvents can strip the conductive layer or leave an insulating film. Do not use wax or silicone polish on an ESD surface. Inspect the mat for cuts and the wrist strap cord for breaks.
Replace the surface when the resistance drifts outside the range or when the surface is damaged. A mat that is repaired with tape is not a reliable ESD surface.
Frequently asked questions
Can I use a standard table with an ESD mat?
It can work for light tasks if the mat is grounded properly and the table is stable. For production, a dedicated bench with a steel frame and a replaceable top is more durable and easier to certify.
How often should wrist straps be tested?
Daily, before work starts. A wrist strap is a wearable item and fails more often than the bench surface.
Does the floor matter?
Yes. A dissipative floor or ESD footwear is needed if the operator is not wearing a wrist strap. The floor, footwear and bench form one system.
Send your ESD control plan and workstation layout to our engineers through the contact page; we will configure the bench and the grounding kit together.
