TECHNICAL BULLETIN TB-2000 Installation and Made in the Maintenance of ESD Mats United States of America Introduction 09814 09817 The purpose of an ESD worksurface is to aid in the prevention of damage to ESD sensitive components and assemblies from electrostatic discharge. An ESD worksurface provides protection in the following two ways: 1. Providing an antistatic worksurface area that will limit static electricity generation. Figure 2. Other ground cords. 2. Removing the charge from a conductive object placed on the worksurface. A dissipative worksurface having a surface resistance of at least 1 6 9 x 10 , but less than 1 x 10 ohms is recommended by worksurface standard ANSI/ESD S4.1. Dissipative materials minimize the generation of static charges, and will dissipate a charge slow enough so that a spark will not occur. Dissipative materials are usually the preferred choice for bench top worksurfaces. Conductive materials are the quickest to remove a charge, Figure 3. 09814 with screw allows ground cord to be bolted to mat but they can also cause damage by discharging too rapidly. to keep cord from disconnecting. Conductive materials are usually used as floor mats, which is 6 defined by ANSI/ESD S7.1 as less than 1 x 10 ohms. Common point grounds are designed to provide ground for General Grounding Guidelines worksurface mats, wrist straps, and other items. NOTE: DO NOT DAISY CHAIN. Because of the high resistances 1. ANSI/ESD S20.20 requires that all conductors in an ESD inherent to many types of protective surfaces, daisy chaining of protected area, including personnel, must be grounded. these materials can severely limit their ability to properly dissipate 2. The ESD ground must be tied directly to and at the same and protect against static charges. potential as the building or green wire equipment ground. 3. Per ANSI/ESD S20.20, the ESD control program can in no COMMON POINT GROUND way replace or supercede any requirements for personnel Per ANSI/ESD S6.1, Grounding section 4.1.1 Every element to be safety. Ground fault circuit interrupters (GFCI) and other safety grounded at an ESD protected station shall be connected to the protection should be considered wherever personnel might same common point ground. come into contact with electrical sources. ESD Handbook ESD TR20.20 section 5.1.3 Basic Grounding 4. All electrical outlets should be verified for proper wiring Requirements The first step in ensuring that everything in an configuration, resistance or impedance and GFCI function when EPA is at the same electrical potential is to ground all conductive the mat is installed and periodically thereafter. components of the work area (worksurfaces, people, equipment, etc.) to the same electrical ground point. This point is called the common point ground. The next step in completing the ground Common Point Grounds circuit is to connect the common point ground to the equipment A common point ground is defined by the grounding standard ground (third wire, green). ANSI/ESD S6.1, as: 1. A grounded device where two or more conductors are bonded. 2. A system or method for connecting two or more grounding conductors to the same electrical potential. Examples of common point grounds with ground cords are WRONG illustrated below. 09835 RIGHT Figure 4. ESD mats should never be grounded in series, that is daisy chained. 09825 09740 09837 Figure 1. Typical common point grounds. DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 (909) 627-8178 DESCO EAST - One Colgate Way, Canton, MA 02021-1407 (781) 821-8370 Web Site: Desco.com 2015 DESCO INDUSTRIES INC. TB-2000 February 2015 Page 1 of 4 Employee Owned2. Desco has three types of 10mm (0.395 ) field installable mat Grounding Methods grounding snaps. The first type is a screw-on snap kit Desco Method 1 (Grounding via ground cords) item number 09864 Universal Snap Kit. 1. Desco recommends using a common point ground cord when A. Determine the position of the grounding snap (one only grounding via ground cords. Most common point ground cords per mat) and type of fastener you will be installing (socket will ground your ESD worksurface and provide banana jack or stud). Take precautions not to cut your hand, and punch ground points for two wrist straps. a hole through the material with a small Phillips screwdriver or awl. 2. A common point ground should be installed at each workstation and should be connected directly to a verified green wire B. Remove the release paper from the circular common point equipment ground. Only one groundable point should exist on a ground label and affix it so that it aligns with the hole on the worksurface. material. C. Select one of the screws as follows: Material less than 0.100 thick - short screw Material greater than 0.100 thick - long screw D. Insert the screw through the top on the snap stud or socket, the washer, the label and the material. Affix the assembly with the conical nut supplied with the kit and tighten down the screw using a Phillips screwdriver. E. Remaining will be either a 10mm stud or socket, and either a long or short screw to be discarded or saved for another application. Figure 5. Common point ground for each workstation. 3. Wrist straps should never be grounded through a worksurface, ASSEMBLE SCREW, STUD, as the added resistance of the worksurface material will WASHER, LABEL AND CONICAL NUT prevent the wrist strap from operating properly. AS SHOWN USE A PHILLIPS SCREWDRIVER OR AWL TO PUNCH A HOLE IN THE MATERIAL WRONG RIGHT Figure 6. Proper grounding of wrist straps. Figure 8. Installing Universal Snap Kit on mat. 4. Per ANSI/ESD S1.1, a current limiting resistor in the wrist strap ground cord is recommended. If other than a one megohm 3. The second type of mat grounding snap is the push and resistor, special marking in red is required. clinch snap. This snap is designed for use with any type of soft mat material: dissipative, conductive or multi-layered. It is For additional information on grounding we recommend Desco recommended for use with three-layered material, because it Technical Bulletin TB-2007. provides excellent contact with the internal con ductive scrim layer. It is recommended that before inserting this snap, the mat be punctured with a sharp tool where the snap will be Groundable Point Installation placed. Take precautions not to cut your hand. Push and Clinch 1. Before installing a groundable point on your mat you must first snaps are available as a snap stud as item 09861 and as a snap determine whether you will need a snap socket or stud, the socket as item 09863. type of snap hardware and the location. A. Remove the release paper from the circular label and affix it onto the mat material in the desired location. B. Center the prongs on the snap assembly with the label. Apply pressure to the snap until the prongs come through the back of the mat, then clinch over prongs to secure snap as shown in Figure 9. Figure 7. Three kinds of snaps. DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 (909) 627-8178 DESCO EAST - One Colgate Way, Canton, MA 02021-1407 (781) 821-8370 Web Site: Desco.com 2015 DESCO INDUSTRIES INC. TB-2000 Page 2 of 4 Employee Owned