ESD Equipment
What is ESD
Electrostatic discharge (ESD) is the sudden flow of electricity between two electrically charged objects caused by contact, an electrical short or dielectric breakdown. The ESD occurs when differently-charged objects are brought close together or when the dielectric between them breaks down, often creating a visible spark.
Modern electronic components are becoming more and more sensitive to static discharge, which leads to antistatic protection requirements broadening and toughening.
Static electricity is often generated through the separation of electric charges that occurs when two materials are brought into contact and then separated. A simple movement, such as human walking by in casual cloths is enough to generate up to 30 000 volts, that is more than enough to harm ESD sensitive electronic components. At the same time electrostatic discharge of less than 2 000 volts will be invisible and imperceptible for a human. Most often electronic components slight damage caused by electrostatic discharge, does not lead to immediate failure of the entire device, but after a certain time, the unit starts to work improperly, or does not work at all, which results in unexpected defects, customers claims and loss of product reputation and future sales.
That's why everything that is used along the process of sensitive electronic equipment production, installation or repairing - from hand tools and clothing to furniture and flooring – should meet requirements of antistatic protection. Thus high-quality antistatic furniture becomes a key element in comprehensive ESD protection.
ESD terms
ESD
Electrostatic discharge is the release of static electricity when two objects come into contact. Familiar examples of ESD include the shock we receive when we walk across a carpet and touch a metal doorknob and the static electricity we feel after drying clothes in a clothes dryer. A more extreme example of ESD is a lightning bolt. While most ESD events are harmless, it can be an expensive problem in many industrial environments.
ESDS
Electrostatic discharge sensitive (devices). Many electronic devices are susceptible to low voltage ESD events. For example, hard drive components are sensitive to only 10 volts. For this reason, manufacturers of electronic devices incorporate measures to prevent ESD events throughout the manufacturing, testing, shipping, and handling processes.
EPA
ESD protected area. ESD prevention within an EPA should involve ESD furniture and tools, appropriate ESD-safe packing material, the use of antistatic garments worn by assembly workers, conductive wrist straps and footwear to prevent high voltages from accumulating on workers' bodies, anti-static mats or conductive flooring materials to conduct harmful electric charges away from the work area, and humidity control. Humid conditions prevent electrostatic charge generation because the thin layer of moisture that accumulates on most surfaces serves to dissipate electric charges. Ion generators (ionizers) are sometimes used to inject ions into the ambient airstream.
The terms anti-static, conductive, and dissipative are all terms that subdivide ESD into more detail. Something insulative is not considered ESD safe.
Materials are divided into these terms based on their individual surface resistance. Surface resistance is a measurement of how easily an electric charge can travel across a medium. Conductive materials are materials that 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.
Anti-static materials are generally referred to as any material which inhibits triboelectric charging. This kind of charging is the buildup of an electric charge by the rubbing or contact with another material. An insulative material is one that has a surface resistance of greater than 1 x 10 12 ohms/square.
Conductivity
The ratio of the current per unit area (current density) to the electric field in a material. Conductivity is expressed in units of siemens/meter. In non-technical usage, the ability to conduct current.
Conductive Material
Material that has a surface resistivity less than 1 x 105 ohms/square or a volume resistivity less than 1 x 104 ohm-cm.
Static Dissipative
Refers to the ability of a material to conduct a charge to ground and is usually indicated by an electrical resistance range measured in Ohms of a minimum of 1.0x 106, to a maximum of 1.0 x 109.
ESD signs
Are a must have in facilities that have areas that need to be static free. These zones require that proper static grounding equipment be used to ensure the safety of all those in the facility. Safety signs like static grounding signs in these areas can help workers stay informed of the static grounding policies.
Decay Time
The time required for an electrostatic potential to be reduced to a given percentage (usually 10%) of its initial value.
Surface resistance
Is the resistance of a surface measured by a concentric ring electrode test method defined in 61340-5-1and IEC 61340-2-3: 2000.
Point-to-point resistance
Is the resistance measured between two electrodes placed on a surface, defined in 61340-5-1, IEC 61340-2-3: 2000.
Resistance-to-ground
Is the electrical resistance measured from a point to the ESD facility electrical earth (usually mains power earth).
Surface resistance
Is the resistance of a surface measured by a concentric ring electrode test method defined in 61340-5-1and IEC 61340-2-3: 2000.
ESD Susceptibility Symbol
The ESD Susceptibility Symbol, consists of a triangle, a reaching hand, and a slash through the reaching hand. The triangle means "caution" and the slash through the reaching hand means "Don't touch." Because of its broad usage, the hand in the triangle has become associated with ESD and the symbol literally translates to "ESD sensitive device, don't touch."
The ESD Susceptibility Symbol is applied directly to integrated circuits, boards, and assemblies that are static sensitive. It indicates that handling or use of this item may result in damage from ESD if proper precautions are not taken. If desired, the sensitivity level of the item may be added to the label
ESD Protective Symbol
The ESD Protective Symbol, consists of the reaching hand in the triangle. An arc around the triangle replaces the slash. This "umbrella" means protection. The symbol indicates ESD protective material. It is applied to ESD furniture, mats, chairs, wrist straps, garments, packaging, and other items that provide ESD protection. It also may be used on equipment such as hand tools, conveyor belts, or automated handlers that is specially designed or modified to provide ESD control
EPA scheme
In sensitive electronics manufacturing, electronics components sub-assemblies and assemblies prevention of ESD (Electrostatic discharge) is based on an Electrostatic Protective Area (EPA). The EPA can be a small workstation or a large manufacturing area. The main principle of an EPA is that there are no highly-charging materials in the vicinity of ESD sensitive electronics, all conductive materials are grounded, workers are grounded, and charge build-up on ESD sensitive electronics is prevented. International standards are used to define a typical EPA and can be found for example from International Electrotechnical Commission (IEC) and its national branches in the form of national Technical committees.
ESD prevention within an EPA should involve ESD furniture and tools, appropriate ESD-safe packing material, the use of antistatic garments worn by assembly workers, conductive wrist straps and footwear to prevent high voltages from accumulating on workers' bodies, anti-static mats or conductive flooring materials to conduct harmful electric charges away from the work area, and humidity control. Humid conditions prevent electrostatic charge generation because the thin layer of moisture that accumulates on most surfaces serves to dissipate electric charges. Ion generators (ionizers) are sometimes used to inject ions into the ambient airstream.
Thus the creation of an EPA is an essential requirement for any company manufacturing or repairing electronics equipment.
ESD includes
1. Yellow ESD label (EPA entering notification)
2. Yellow ESD label (EPA whereabouts notification)
3. Yellow ESD label (EPA leaving notification)
4. Wrist straps and footwear tester
5. Footwear tester plate
6. Footwear and wrist straps testing protocol
7. ESD linoleum
8. Worktop grounding cable
9. Shelves grounding cable
10. Conductive wrist straps
11. Antistatic mat
12. Connecting plug for grounding cables
13. ESD boxes
14. SMD cabinet
15. L-shape PCB holder
16. Soldering station in ESD version
18. Ionizer
19. ESD tools
21. ESD laboratory chair
22. ESD footwear
23. ESD garments
24. Conductive binders
25. ESD waste bin
26. Alliance series workbench
27. Classic series workbench
28. Movable table
29. Shelvings
30. Hygrometer
31. Grounding panel
32. Floor adhesive tape with ESD marks