ESD (electrostatic discharge) is the sudden transfer of static electricity between objects at different electrical potentials. In electronics manufacturing, a discharge can damage or weaken sensitive components during handling, assembly, testing, or shipping. Any team building or sourcing electronic products needs controls that prevent charge from reaching exposed parts.
What Causes Electrostatic Discharge?
Static charge builds when two materials contact and separate. Pulling tape from a reel, removing a plastic tray, or sliding a PCB across a fixture can all create charge. Friction, motion, and low humidity can leave a person, bag, fixture, or ungrounded metal object at a different potential from an electronic assembly.
The discharge happens when that potential finds a path to equalize. A handler touching an exposed PCB, a connector meeting a charged cable, or a device sliding in a plastic tray can provide it. People often do not feel the smaller events that still matter to modern ICs, so “I did not get a shock” is not an ESD control plan.
Why Is ESD Dangerous for Electronic Components?
An ESD event can puncture a thin oxide layer, damage a semiconductor junction, or melt a tiny metal path. Some damage is catastrophic and shows up at test. Other damage only weakens the part, leaving a product that works through final inspection and then fails after time in the field.
| Damage type | What happens | When it is found | Business consequence |
|---|---|---|---|
| Catastrophic damage | The component no longer functions or is out of specification. | Usually during assembly or functional test. | Scrap, rework, and delayed production. |
| Latent damage | The component remains functional but has reduced margin or reliability. | Possibly after shipment under normal operating, thermal, or electrical stress. | Field returns, hard-to-reproduce failures, warranty cost, and a damaged customer relationship. |
ESD is related to electrical overstress (EOS), but they are not interchangeable. ESD is a fast discharge of built-up static charge. EOS is the broader condition where excessive voltage or current damages a device, often over a longer interval. Infineon’s ESD and EOS application note helps separate the two mechanisms during failure analysis.
Which Components Are Most Sensitive to ESD?
Any exposed electronic assembly deserves ESD handling, but sensitivity differs by device and by pin. Modern semiconductors with small structures and low-voltage inputs often have little tolerance for careless handling. The component data sheet should set the product-specific rules.
| Component type | Why it is vulnerable | Practical handling point |
|---|---|---|
| CMOS ICs and MOSFETs | Thin gate oxides and sensitive input structures can be damaged. | Keep leads and exposed boards inside an ESD-protected area. |
| RF ICs and transceivers | High-frequency input paths can have limited protection margin. | Use grounded tooling and approved trays during tuning and test. |
| Memory and microcontrollers | I/O pins may be exposed while boards are programmed or debugged. | Control the programmer, cable, operator, and bench together. |
| Power semiconductors and IGBTs | Gate and control terminals can be sensitive even when the device handles high load power. | Follow the supplier’s handling and packaging instructions. |
How Is ESD Prevented in Electronics Manufacturing?
Effective prevention keeps people, equipment, components, and work surfaces at the same electrical potential, while removing charge where it cannot be avoided. The goal is to stop an uncontrolled discharge from crossing a sensitive device.
| Control | What it does | What to verify |
|---|---|---|
| Grounded personnel | Wrist straps, footwear, and garments connect trained operators to the ESD control system. | Strap and footwear testing, correct use, and documented training. |
| ESD-protected workstations | Dissipative mats, grounded tools, and common-point grounding prevent harmful potential differences. | Ground continuity, surface resistance, and workstation condition. |
| Ionization | Neutralizes charge on essential insulators that cannot be grounded. | Placement, balance, cleaning, and maintenance records. |
| Protective packaging | Shields or dissipates charge during storage and transport between controlled areas. | Correct packaging type and closed-pack handling rules. |
Automated optical inspection can catch solder, placement, and polarity defects, but it cannot reliably reveal microscopic ESD degradation inside a semiconductor. Prevention, verification, and appropriate electrical test must work together.
What Standards Govern ESD Protection?
For many electronics manufacturers, ANSI/ESD S20.20-2021 is the core program standard. It defines administrative and technical requirements for establishing, implementing, and maintaining an ESD control program. In Europe, IEC 61340-5-1 is commonly used and is technically equivalent to S20.20.
These standards concern a factory program, not simply purchasing an “ESD certified” mat. They cover responsibilities, a written control plan, training, protected areas, grounding and bonding, packaging, product qualification, and compliance verification. A supplier should be able to show how those pieces operate on its actual line.
How to Know If Your Manufacturing Partner Has Proper ESD Controls
Ask for evidence before production, then check that it matches the line that will build your product. A polished certificate is useful, but it does not show whether an operator on the night shift tested a wrist strap or whether an open PCB sat in an ordinary plastic tote.
- Request the current ESD control plan and the standard it follows, such as ANSI/ESD S20.20 or IEC 61340-5-1.
- Ask who owns the program, how operators are trained, and how often stations, grounding, footwear, and wrist straps are verified.
- Confirm the handling path from incoming parts through assembly, test, rework, storage, and shipment. The weak point is often between departments.
- Ask for the ESD sensitivity information used for your BOM, including any special rules from semiconductor suppliers.
- Review photos or audit the actual ESD-protected areas, packaging, and rework benches used for your build.
- Require notification if a component, tray, packaging material, process, or test fixture changes.
ESD risk should be addressed during design for manufacturing, when layout, enclosures, connectors, test access, packaging, and production flow can still be changed without turning a small issue into a tooling and schedule problem. The cost of a late redesign is usually much higher than the cost of asking better questions at the quotation stage.
At Titoma, compliance documentation and production controls are reviewed with the build plan so clients can see how sensitive assemblies are handled from sourcing through shipment. That paper trail is useful when a field issue needs a disciplined failure analysis instead of a round of guesses.
FAQs
Can ESD damage a component that still passes factory testing?
Are wrist straps enough to protect electronics from ESD?
What is the difference between ESD and electrical overstress?
Can automated optical inspection detect ESD damage?
How often should a factory verify ESD controls?
