Design Selection of Anti-static Workbenches
Anti-static workbenches are specialized workbenches provided by the EPA (Electrostatic Protected Area Service). They are a core component of EPA protection and, in addition to the anti-static workbench, wrist straps, anti-static chair, and anti-static tools, should be equipped with a grounding monitor so that operators can monitor the grounding system's condition at any time. The material of the anti-static tabletop should be grounded using all necessary methods. To prevent direct short circuits to ground from any exposed metal contacts, a 1-megohm grounding busbar should be used. Similarly, the connection between the wrist strap and the grounding return line should also use a 1-megohm grounding resistor, connected using methods such as alligator clips, banana plugs, or snap fasteners.
Operating ESDS-sensitive devices and electronic instruments on such a workbench can prevent damage caused by electrostatic discharge, electrostatic induction, or electrostatic adsorption.
The wrist strap connection device, current-limiting resistor, and grounding lead are unique components of anti-static safety workbenches. The wrist strap connection device is specifically designed for connecting anti-static wrist straps. The 1-megohm current-limiting resistor on the wristband is designed to ensure human safety, ensuring that in the event of electric shock or other dangerous situations, the safe current passing through the human body does not exceed 5mA. The grounding lead is configured for grounding the anti-static workbench. Anti-static workbenches vary in form and have various attached components, but they all have five essential parts: the workbench, the anti-static work surface mat, the wristband connection device, the current-limiting resistor, and the grounding lead.
In terms of materials, ordinary anti-static workbench surfaces are made of wood or other inorganic materials, and the surface may be covered with a decorative panel. Repurposed anti-static safety workbenches have an anti-static mat on the surface. Rigid mats are mainly used in Class I anti-static work areas, but their surface resistance or volume resistivity should meet the requirements of 2.5*10^4 ohms-1.0*10^9 ohms. The wristband connection device is a necessary facility for grounding the anti-static wristband worn by the human body. This clause specifies the installation location requirements from an ergonomic perspective.
Currently, anti-static wrist straps with built-in button-type current-limiting resistors are available; therefore, this specification does not specify the installation location of the current-limiting resistor. However, the current-limiting resistor should be considered a necessary component of the anti-static workbench in all cases.
When multiple anti-static safety workbenches are used, the grounding wires must not be connected in series to ensure reliable grounding at each workstation.
Only by correctly following operating procedures can the equipment be used to its fullest potential, leaving no place for static electricity to hide.