All US based Desco Industries locations will be closed on Monday May 29, 2017 in observance of the Memorial Day Holiday. Customer service will be closed for the day and no orders will be processed for the day. Normal operations will resume on Tuesday May 30, 2017.
ESD worksurfaces, such as mats, are typically an integral part of the ESD workstation, particularly in areas where hand assembly occurs. Carts or shelves where ESD sensitive items are stored (without ESD shielding) would also be treated as an ESD workstation. The purpose of the ESD worksurface is two-fold:
- To provide a surface with little to no charge on it.
- To provide a surface that will remove ElectroStatic charges from conductors (including ESD Susceptible devices and assemblies) that are placed on the surface.
ESD mats need to be grounded. A ground wire from the mat should connect to the common point ground which is connected to ground, preferably equipment ground. For electronics manufacturing, a worksurface resistance point to point (Rtt) of 1.0 x 10^6 to less than 1.0 x 10^9 ohms is recommended.
The best practice for grounding is that ground connections use firm fitting connecting devices such as metallic crimps, snaps and banana plugs to connect to designated ground points. Use of alligator clips is not recommended.
The worksurface must be maintained and should be cleaned with an ESD cleaner. Regular cleaners typically contain silicone. They should never be used on an ESD worksurface because the silicone will add an insulating layer. The ESD control plan should require testing the resistance to ground periodically. However, the operator should be on guard every day and check visually that the ground wire is attached.
For more information, contact Desco.
When elastic wristbands wear out and loose their elasticity, the band can easily be replaced. There is no need to replace the entire wristband, which saves money. Desco’s elastic replacement strip is easy to replace with no tools. Watch the video to learn more.
See Desco’s elastic replacement strip.
ESD worksurfaces are typically an integral part of the ESD workstation, particularly in areas where hand assembly occurs. The purpose of the ESD worksurface is two-fold:
(1) To provide a surface with little to no charge on it.
(2) To provide a surface that will remove ElectroStatic charges from conductors (including ESD Susceptible devices and assemblies) that are placed on the surface.
For an electronics manufacturing environment, the worksurface resistance point-to-point (Rtt) and point-to-ground (Rtg) of 1.0 x 106 to less than 1.0 x 109 ohms is recommended(ANSI/ESD S4.1). Worksurfaces can be defined as any surface that un-packaged ESD susceptible devices or assemblies placed in direct contact with. Worksurfaces can include, mats, laminates, trays, carts, shelves, and other storage or handling devices that do not have an ESD shielding function. A ground wire from the mat should connect to the common point ground which is connected to ground, preferably equipment ground.
All ESD worksurfaces should be systematically tested for Rtg using a resistance megohmmeter with a 5 lb. electrodes. This should become part of a regular compliance verification plan. Surfaces should be confirmed at least two to four times per year and whenever a workstation or bench is moved or installed. ESD mats where the Rtg measures > 5 x 108 or greater should be considered for replacement before they are out of spec.
The worksurface must be maintained and should be cleaned with an worksurface ESD cleaner. Regular cleaners typically contain silicone. They should never be used on an ESD worksurface because the silicone will add an insulating layer. The ESD control plan should require testing the resistance to ground periodically.
For more information on best practices for establishing and ESD workstation, contact Desco.
Desco manufacturers products in several factories in the USA. In addition, Desco leases 450 acres of prime agricultural property in Chino Valley where we grow coil cords for wrist strap production. An on-site facility conducts research in pest control, soil testing, and bio-sustainability. Future plans include growing ground cords, vinyl berries, and breeding alpacas for improving their natural static-dissipating hair for use in woven wristbands. Desco is committed to using local-sourced materials that are eco-friendly and sustainable.
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ANSI/ESD S20.20 now requires the Operator Walking Test (ANSI/ESD STM97.1) and conformance to Operator Resistance Measurements (ANSI/ESD STM97.2) for product qualification of flooring / footwear systems for grounding personnel.
What is the importance of the Walking Test?
- It is necessary to qualify the Footwear / Flooring personnel grounding system for certification to ANSI/ESD S20.20.
- It can provide records to prove that Footwear / Flooring personnel grounding system used as a static control method is actually providing the performance expected.
- It is used when testing samples for qualification of a Footwear / Flooring personnel grounding system or on an existing installed floor when evaluating a change in footwear or flooring maintenance.
For Product Qualification, what Operator Resistance Measurements does ANSI/ESD S20.20-2014 state product should test to?
- < 100 volt peak voltage per ANSI/ESD STM97.2 Voltage in Combination with a Person.
- < 1 x 109 ohms Resistance per ANSI/ESD STM97.1 Resistance in Combination with a Person.
These are both to be performed in a walk-in environment chamber, including 12% RH.
For more information on the Walking Test and ANSI/ESD STM97.2, click HERE for the ESD Association’s PowerPoint.
Want more information? Sign up for a Free Flooring / Footwear Assessment. The Assessment will only take about 30 minutes of your time. We will demonstrate the Walking Test and provide more information on how you can be sure your Flooring / Footwear personnel grounding system meets the current S20.20 guidelines.
DESCO now manufactures a series of bags which are qualified to MIL-PRF-81705E Type III, Class 2. These products are on the Qualified Product Listing under the Defense Standardization Program. Check our listing HERE.
Standard stock bags are converted per MIL-DTL-117H. For standard sizes and further see the product pages HERE.
The DESCO 81705 bags are made and stocked in our Sanford, NC facility.
Please contact Service@Desco.com for more information.
A fundamental principle of ESD control is to ground conductors including people at ESD protected workstations. Wrist straps are the first line of defense against ESD, the most common personnel grounding device used, and are required to be used if the operator is sitting. The wristband should be worn snug to the skin with its coil cord connected to a common point ground which is connected to ground, preferably equipment ground.
If continuous monitors are not used, a wrist strap should be tested while being worn at least daily. Part of the path-to-ground is the perspiration layer on the person; an operator with dry skin may inhibit the removal of static charges and may cause a test failure. Specially formulated ESD lotion can solve this problem. Failures may also be caused by dirty or loose wristbands which should be cleaned or tightened. When a wrist strap fails a test, the supervisor should be contacted, and the failure effectively addressed or the wrist strap replaced.
A Footwear / Flooring system is an alternative for personnel grounding for standing or mobile workers. Foot grounders or other types of ESD footwear are worn while standing or walking on an ESD floor. Both ESD footwear and ESD flooring are required. Wearing ESD footwear on a regular, insulative floor is a waste of time and money.
ESD footwear is to be worn on both feet and should be tested independently at least daily while being worn. Unless the tester has a split footplate, each foot should be tested independently, typically with the other foot raised in the air.
If an operator leaves the ESD Protected Area and walks outside wearing ESD footwear, care should be taken not to get the ESD footwear soiled. Dirt is typically insulative, and the best practice is to re-test the ESD footwear while being worn each time when re-entering the ESD Protected Area.
Contact Desco for more information on Personnel Grounding.
To shop personnel grounding products, click HERE.
How to Measure Resistance Point-to-Point (Rtt) or Surface-to-Ground (Rtg) in Accordance with ESD Association Documents
The Desco Digital Surface Resistance Meter Kit measures resistance point-to-point (Rtt) or surface-to-ground (Rtg) of worksurfaces, flooring systems, garments, and other materials in accordance with ESD Association documents: ESD TR53, ANSI/ESD S4.1, ANSI/ESD S7.1, ANSI/ESD STM97.1 and other documents.
Learn more about Desco’s Digital Surface Resistance Meter Kit Here