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Basics of static electricity countermeasures

Static electricity countermeasures (ESD countermeasures) are becoming essential in manufacturing sites that handle electronic devices.

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Principles of static electricity countermeasures

1. Grounding (earth)

The basic principle of static electricity countermeasures is to ground (release to the earth) the static electricity generated, rather than keeping it in place. All conductors that could be electrically charged should be connected from the ground wire to the earth.
Earthing also maintains charge balance against electrostatic induction.

Grounding (earth)

2. Avoid creating a potential difference

When earth cannot be secured, the following method should be used.
Short-circuiting a potentially charged object and a static-sensitive device allows two substances to become one electrostatically, with no potential difference being created.
This results in no charge transfer and no static buildup.

Avoid creating a potential difference

3. Increasing capacitance

This is another method to use when earth cannot be secured.
If it is impossible to connect to the earth (the planet), which has the largest capacitance, it may be possible to secure capacitance that does not lead to electric discharge even if some static electricity is generated.
However, as a countermeasure, this is uncertain and cannot be recommended for routine use in actual workplaces.

Increasing capacitance

4. Neutralize

If countermeasures 1 through 3 are ineffective, such as when the object is an insulator, a static electricity removal device (ionizer) is used.
Spraying positive and negative ions enables active neutralization of charge bias.

Neutralize

Static electricity countermeasures and preventive equipment for workers

Static electricity countermeasures and preventive equipment for workers

*These countermeasures are required if surface resistance, point-to-point resistance, or resistance to a groundable point exceeds 1 × 10^10 Ω, if the material is not homogeneous, or if the structure has insulating parts.

Source: HOZAN TOOL IND. CO., LTD.

Conductive color mat (for desktop)

Within the EPA, ESD countermeasures must be taken for all surfaces that might come into contact with ESDS items. Countermeasures must be applied not only to work surfaces, but also to the surfaces of device storage racks and temporary storage areas for large machine peripherals.

Antistatic mats/sheets

Work tool

The gripping portion of a typical tool is an insulator, but tools used within the EPA are required to have no insulator. Select tools with conductive material in the handle.

ESD chip tweezers and micro-wire cutters

Wrist strap

Wearing a wrist strap is one of the basic static electricity countermeasures for human workers. Workers within the EPA must wear a wrist strap. Cordless wrist straps that are available in the market are effective in preventing electric shocks, but they are ineffective in terms of device protection and should not be used.

Wrist/footstraps

Color mat (for floor)

ESD countermeasures should be applied to floor surfaces in the PA where workers and carts carrying devices pass by. The mats for floors contain reinforcing fibers that prevent stretching and tearing even after long-term laying.

Antistatic mats/sheets

Grounding is permitted on the human body to footwear to the floor for standing work where wrist straps cannot be worn. The floor in this case must be controlled by a lower resistor value in a separate system from the normal antistatic floor.

Antistatic mats / sheets

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