Static Electricity Countermeasures for the Manufacturing Industry

2021/02/02

Effects of static electricity on manufacturing

Static electricity has various adverse effects on manufacturing.

For example,

• Static charge buildup in the trays (including carrier tape) used to hold electronic components, resulting in dust adhering to components
• Static charge buildup in PET film and other plastic films, resulting in dust adherence
• Damage to electronic components due to electrostatic discharge
• Explosions caused by static electricity discharge igniting organic solvents or dust

Various antistatic methods

Static electricity has various adverse effects, so what can be done to prevent it?
This can be prevented by being a condition that is difficult to be charged, or one that can be quickly eliminated even if charged.
It is important to have a pathway for electrons (electricity).

Ground conductors

In the case of conductors, electrons move smoothly, so grounding part of the conductor creates a path for electrons to flow into or from the earth, helping prevent static electricity from accumulating. However, electrons do not flow smoothly in insulators, so grounding is not effective for them.

Raise the humidity

When the humidity level is high, a large amount of moisture clings to the surfaces of materials. This moisture increases the electrical conductivity of the surface of the material, making it less prone to static buildup. One of the reasons you seldom hear about static electricity during the summer is because the humidity level is higher.
However, in applications where humidity must be avoided, or in situations where humidity cannot be controlled, this approach is not a viable one.

Supply ions

An ionizer can be used to provide a charge that counteracts the static buildup, neutralizing it.
This is easy to do, but is only effective in environments with ionizers.

Turn insulators into conductors (knead-in)

Static electricity builds up easily in insulators such as plastic and rubber, so one approach is to knead in particles of electrically conductive material during the formation process. Examples of materials that are kneaded in when using this approach are carbon black and surfactants.
Kneading in these materials makes the entire resulting material a conductor, so although it will be highly durable, this approach could negatively impact the intrinsic properties of the material.

Make the surfaces of insulators into conductors (coating)

The electrically conductive coatings can also be applied to the surfaces of insulators. This approach is simple, so it is widely used.
There are two categories of coatings: ion conduction, which uses surfactant as a coating, and electron conduction, which uses metal or electrically conductive polymer as a coating.
With ion conduction coating, the hydrophilic groups of the surfactant attract moisture from the atmosphere to the surface of the material, and the movement of ions in the moisture transports electrons. This approach requires moisture, so it is less effective in low humidity environments.
As its name implies, in electron conduction coating, the coating itself provides the path for electrons to travel.
Denatron is one example of this type of coating. It is based on PEDOT:PSS, an electrically conductive polymer.

The indicated surface resistivity is the resistivity per unit area. The lower the figure, the better electricity is conducted.
In antistatic measures, a surface resistivity of 10⁴ to 10¹³Ω/sq. is often used. As you can see from this data, the effectiveness of ion conduction coating suffers when the humidity is low.

Please see our product information page for more details regarding antistatic grade coatings.