What are ESD Tile, Conductive Tile and Static Dissipative Tile ?
ESD Tile is ESD-safe floor tile for ESD Protected Area (EPA) per ESD S20.20 standard. There are two types of ESD Tiles, namely Conductive Tile and Static Dissipative Tile.
Perceived Understanding About Static Dissipative Tile
Generally we tends to perceive static dissipative floor tile is safer to human than conductive tile when it comes to electrical shock hazard. In other words we tends to think that human exposed to electrical leakage has better chance of surviving on static dissipative tile which has higher electrical resistance than conductive tiles. However conductive tile has electrical resistance range that starts from 2.5 x 104 Ohm (not zero ohm) and according to NFPA 99 and UL779, this is good to be used as electrically-safe flooring for human.
In the past, the majority of companies selected their particular ESD control floors based on the misconception that static dissipative materials were safer than, while still equal in effectiveness to, conductive materials. This widespread fallacy led to the installation of millions of square feet of static dissipative flooring. However, the current trend is more conductive tiles being chosen by Electronics and Semiconductor manufacturing facility for better ESD performance in human body voltage control (HBM).
How Do I Ground My Conductive / Static Dissipative Floor ?
Whether it is conductive or static dissipative floor, both should be grounded to a known earth ground. A known earth ground can either be earth of the electrical main service equipment or a dedicated ESD ground that is proven to be well grounded. Key consideration here should be to ensure all grounding systems (ESD ground, electrical ground, building earth ground) are of equal potential to prevent leakage current resulting from different potential at different grounding points.
Maintenance Procedure For Conductive / Static Dissipative Tiles
Maintaining Conductive / Static Dissipative tiles is easy. Daily sweeping and damp moping with clean water is sufficient for most applications. Weekly wet mop with neutral detergent is good cleaning practice for Conductive / Static Dissipative Tiles. You might want to buff the Conductive / Dissipative tiles monthly or bi-monthly to remove stubborn dirt.
Can conductive floor be used as means of ESD Control in working environment where technician without ESD Footwear were to handle PCB with ESD sensitive components?
All Conductive floor need to work together with ESD Footwear (eg. heel strap, ESD Shoes) for personnel grounding as means of ESD Control. However technicians without ESD footwear could still safely handle ESD sensitive components if they were wearing wrist strap. If you could ensure technicians were to wear wrist strap every time they handle ESD sensitive devices, you actually do not need to install conductive floor for cost saving purposes. However if you do decide to install conductive floor and at the same time have your technician wearing ESD footwear then you have the advantage of allowing technician to freely move around the conductive floor while he/she handles ESD sensitive devices without wearing wrist strap (remember wrist strap restrict technician's movement as he/she is "tied-up" by the wrist strap cord).
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