grounding

 

How to Design an Esd Workstation

September 28, 2011

An ESD Workstation is a work area with materials and equipment that limit electrostatic voltages and ESD (electrostatic discharge) or more commonly referred to as Static.

The first step in protecting a workstation is to ground all components of the work area (work surfaces, people, equipment, etc.) to the same electrical ground point called the “common point ground.”

While it is recommended to take every precaution available to control static, not all the ESD steps below may be necessary for basic ESD protection. Your workstation may not require all these items. Call Transforming Technologies for help designing your ESD workstation

ESD Protection Steps

1. ESD Table Mat

A work surface that removes static from conductive items placed on it. Commonly made from durable materials such as rubber, vinyl or laminate. A 10mm grounding snap should be installed in the mat or every 10 ft if it is long.

2. Wrist Band and Coil Cord Set

Safely grounds a person working at a workstation.  It is worn around the wrist and is connected to ground through a long coiled cord and the common point ground.

3. Common Point Ground

Used for grounding ESD mats and provide a path-to-ground for the person wearing wrist straps.  It attaches to the ESD worksurface via the 10mm grounding snap.

 

4. ESD Floor Mat

ESD floor mats remove static charges from conductive items placed on it. ESD footwear such as a Heel Grounder must be worn to remove static from the person standing on the mat. It is best used for mobile personnel that cannot be tethered to one location by a wrist strap.   A grounding snap should be installed in the mat or every 10 ft if it is long.

5. ESD Floor Mat Ground Cord

Used for grounding the floor mat by providing a path-to-ground for an ESD floor mat.  Connects to the mat via a grounding snap.

6. ESD Heel Grounders

Worn on each shoe to connect a walking or standing person to ground.

7. Constant Monitors

These electronic devices continuously monitor the path to ground of a wrist strap, work surface and other grounded components on a workstation.  Eliminates the need to test wrist bands and protects against ground failures.

8. ESD Jackets

Provide shielding from static charges on your clothing. A “Hip-to-Cuff” grounding system ensures proper grounding without requiring wristbands being worn that can inhibit your movement.

9. ESD Equipment Testers

ESD wrist strap and heel grounders, like any equipment used every day, can wear. Ensure these items are in proper working order with ESD Equipment testers.

10. ESD Air Ionizers

Materials, called insulators, cannot be grounded by typical means.  Ideally insulators should be removed from the workstation, but if they must stay an ESD Air ionizer can neutralize static buildup.  Delivering a balanced stream of ionized air, ionizers remove static charges from insulating materials and isolated conductors.

Every situation is unique and requires different steps to properly manage a static situation.

Stationary Personnel

Mandatory Steps: 1,2,3

Suggested Steps: 7,9

Optional Steps: 4,5,6,7,10

Mobile Personnel

Mandatory Steps: 4,5,6

Suggested Steps: 9

 

How to Choose an ESD Mat

June 16, 2011

ESD MattingAn ESD mat is a very important part of an ESD protected area.  ESD mats are designed to eliminate static on its surface and of objects placed upon it.   It does this by having a conductive material embedded within the mat that collects the static and sends it to ground (earth). This is usually accomplished by connecting the mat to ground (typically the center screw of an outlet) with a ground cord. It’s important to discharge at a slow rate, therefore a resistor in the ground cord is recommended.

A quick search online or in ESD catalogs reveal a myriad of ESD mat options.   What are the main considerations in choosing an ESD mat?

Material:

ESD mats are generally found in two categories:  Vinyl and Rubber.  ESD Rubber mats are the most widely used mat material because they have a high resistance to heat and most chemicals.  ESD Vinyl mats are also used for tabletop or work surface applications. They are easy to cut, and some varieties provide cushion. The type of material is a primary concern if you will be using a constant monitor because some materials are incompatible with certain constant monitors.

Composition:

ESD mats are available in single, two and three layer material. Mats are made of a single homogenous conductive layer material, two layers of static dissipative rubber material or vinyl with a conductive material sandwiched between two layers.  Thickness, texture, and cushioning of the mat are also concerns depending on the application.  Regardless of composition, all mats should meet or exceed the requirements of ANSI ESD-S20.20.

Size:

ESD matting typically comes in 50′ or 60′ rolls in four standard widths: 24″; 30″; 36″ and 48″.  The material is easy to cut and has a long shelf life so if you have more than one area to cover or expansion is a possibility, purchase a full roll and cut pieces as needed.  Many suppliers also provide ready-to-use pre-cut mats with grounding hardware already installed.  These mats can be more expensive, but it can also be a great time saver.

Electrical Performance:

All static control mats are not created equally.  The ESD mat’s long-term electrical properties are tantamount to successfully controlling an ESD event. The terms insulative, conductive, and dissipative are all terms that subdivide ESD materials based on their individual surface resistance. Surface resistance is a measurement of how easily an electric charge can travel across a medium (Visit here to learn How To Test ESD Mats). Conductive materials have a surface resistance of less than 1 x 10 5 ohms/square. Dissipative items have a surface resistance of more than 1 x 10 5 ohms/square but less than 1 x10 11 ohms/square. An insulative material is one that has a surface resistance of greater than 1 x 10 12 ohms/square. Based upon your application, ESD mats should be in either the dissipative or conductive range. Something insulative is not considered ESD safe.

Conclusion:

When choosing an ESD mat, first use your specific application to narrow your choices, such as mat material and electrical properties.  Carefully plan and budget your workstation and estimate wear and tear so that you can choose to purchase a full roll or a pre-cut mat.  Finally, do not let cost dictate your decision – saving a few dollars on low quality matting could have very costly consequences via catastrophic damage, latent failures and customer complaints.

For help choosing your ESD mat, please call Transforming Technologies at 419-841-9552 or email info@transforming-technologies.com

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