Static Neutralization Equipment

|Why is static electricity generated?

Principle of static electricity

When looking closely, you can see that all matter is composed of atoms.
An atom has protons and electrons that are in electrical balance.
Electrons may become separated from or attached to the atom with a small force.
Disruption of the balance between protons and electrons leads to static electricity.

No static electricity (0 V)	Positively charged (+)	Negatively charged (–)
Protons (+) and electrons (–) are balanced and no static electricity is generated.	When an electron (–) separates from the atom, the number of protons (+) exceeds the number of electrons (–), resulting in a positively charged state.	When an electron (–) attaches to an atom, the number of electrons (–) exceeds that of protons (+), resulting in a negatively charged state.

Note) 3 electrons are mentioned in the figure, but the number of electrons varies depending on the atom.

|Causes of generating static electricity

1. Contact charging

When 2 objects come in contact with each other, electrons can move between the objects. When the objects are suddenly separated under this condition, the atoms are polarized and static electricity is generated.

	Both objects (workpieces) have the same number of protons and electrons and are electrically balanced. Neither object generates an electric potential (static electricity).
	When one object (workpiece) comes into contact with another object (workpiece), electrons (–) move from the workpiece with the small work function to the workpiece with the large work function. < Work function: The minimum amount of energy required to remove an electron from the surface of a metal. Each substance has all eigenvalues. >
	When objects are suddenly separated, the distribution of electrons becomes polarized, resulting in negative or positive charging depending on the number of electrons.

Electric Polarity and the Amount of Electric Charge

Triboelectric series

The "electric polarity" and "amount of electric charge" when 2 objects come into contact with each other, are shown in the triboelectric series.

How to read the triboelectric series

1: Electric polarity

The materials mentioned in the upper part of the triboelectric series are charged positively and those mentioned in the lower part are charged negatively. Example 1: Glass (+) Polyester (–) Example 2: Polyester (+) Fluororesin (–)

2: Electric charge

As the distance between 2 materials becomes greater, the amount of charge becomes larger.
Example 1: Amount of charge between the human body and nylon (Small)
Example 2: Amount of charge between the human body and polyurethane (Large)

2. Induction charging

Induction charging is static electricity that is generated when a charged object gets close to another object without contacting it. This static electricity is difficult to detect because the objects do not come into contact with each other.

When protons and electrons are balanced, an electrostatic meter does not detect static electricity. When a charged object gets close to another object, electrons are attracted and polarized and the electrostatic meter indicates positive. When the charged object touches another object under this condition, it discharges. When the charged object is separated, it returns to its original state.

Examples of Failures due to Induction Charging

Device Breakdown 1

1) An uncharged device has no electrical polarization.

2) When a vacuum pad that has been charged due to repeated operations gets close to the device, static induction occurs. This figure shows that electrons move toward the electrode: the chip and its surroundings are positively charged.

3) When the device is mounted on a circuit board, electrostatic discharge occurs. In this case, a conductive rubber pad needs to be used.

Device Breakdown 2

1) An uncharged device has no electrical polarization.

2) When an operator gets close to the device, induction charging occurs. The operator side of the device is negatively charged and the other side is positively charged.

3) When the device is grounded under this condition, static electricity is discharged. Electrons (–) flow into the device from the ground.

4) If the device is insulated, it becomes negatively charged when the operator leaves the device due to the remaining electrons.

5) When the device is once again grounded, electrostatic discharge occurs again. Electrons (–) flow out.

|Ion charging

Equipment using ultraviolet light etc. may generate ions.
When those ions become attached to workpieces, workpieces become charged.