What is ESD?

What does ESD mean?

ESD stands for electrostatic discharge: electrical charge is transferred between objects at different electrical potentials. A discharge need not be visible or perceptible. Damage depends on component sensitivity and the particular discharge situation.

Why it matters throughout your process

Sensitive electronics are handled during development, manufacturing, testing, storage and transport. Charging and discharge can occur at every interface. Protection therefore needs to cover the whole process chain.

• Immediate failure: a component may stop working or operate outside its specification.
• Hidden damage: damage may not cause an immediately detectable functional failure, making subsequent problems harder to identify.

Component sensitivity is not one universal value

Manufacturer data and the test model determine how sensitivity should be assessed. Human Body Model (HBM) and Charged Device Model (CDM) values describe different discharge situations and are not interchangeable. Passing test levels are not exact destruction thresholds and do not establish a universally acceptable charge on a person.

Human perception is not a test method: the absence of a felt spark does not mean the absence of risk.

How critical situations arise

• Contact and separation: charge transfer can occur when materials touch and separate, for example when removing films or adhesive tapes.
• Charged insulators: plastics may retain charge. A simple grounding connection does not reliably remove it.
• Fields and induction: an electric field can redistribute charge in a nearby conductor, creating a possible discharge situation.
• Missing equipotential bonding: isolated conductors or people may be at a different potential from a component. Contact can cause a sudden charge transfer.

Five principles for effective protection

• Enable people: everyone understands the rules relevant to their tasks.
• Establish equipotential bonding: provide suitable grounding of people and conductive or dissipative elements.
• Control insulators: remove unnecessary insulating materials and assess those required by the process.
• Verify effectiveness: qualify, verify and maintain protection measures.
• Cover the process chain: coordinate protection at handovers, packaging, suppliers and customers.

A system, not isolated products

Start with product sensitivity and process risks. Define suitable measures and verify that they remain effective in use. Clear responsibilities, trained people, suitable materials and defined checks belong in the ESD control programme.

Distinguish ESD from EOS

EOS means electrical overstress. A damage pattern alone does not prove that ESD was the cause. A reliable diagnosis requires examination of the component and the process.