The damage you cannot feel
A person usually becomes aware of a static discharge somewhere around two to three thousand volts. Many semiconductor devices are damaged well below that — some by a few hundred volts, and the most sensitive by less than a hundred. The practical consequence is uncomfortable: most damaging discharges are never noticed, and the part may still pass a functional test at the bench.
This is why ESD control is treated as a process discipline rather than an occasional precaution. The part that fails months later in the field is often the one that was subtly degraded during handling, not the one that was obviously destroyed.
Two kinds of damage
- Catastrophic. The device is destroyed outright and fails immediately. Painful, but at least detectable.
- Latent. The device is partially degraded — a weakened oxide, a narrowed trace. It passes inspection, ships, and fails later under temperature or load. Latent damage is the expensive one, because the failure appears somewhere else entirely: in the field, or in a customer's line.
Because latent damage is invisible, prevention cannot be replaced by inspection. There is no test at goods-in that will reliably screen a degraded part.
Three models, one common cause
ESD sensitivity is normally expressed against standard models, so that ratings can be compared:
- Human body model. A charged person touches the device. This is the model most people picture.
- Charged device model. The device itself is charged — by sliding out of a tube, being picked from a tape pocket, or moving across an insulative surface — and then discharges into the first conductor it meets. In automated assembly this is often the dominant mechanism, which is why a grounded operator alone does not solve the problem.
- Machine model. A charged conductive object, such as a tool or handler, discharges into the device.
Handling rules that only address the operator miss the charged-device case entirely.
Not all packaging protects — the grades differ
This is the most consequential misunderstanding in the whole subject. Packaging sold for electronics comes in grades that do quite different jobs:
- Anti-static / dissipative (typically pink). Designed not to generate or hold a charge. It prevents the bag from becoming a source of static. It does not shield the contents from an external discharge.
- Shielding (metallized, often grey or silver). Contains a conductive layer acting as a Faraday enclosure, so an external discharge is diverted around the contents. This is what protects parts in storage and transit.
- Conductive. Lowest surface resistance; used for bins, trays and foam where a controlled path to ground is wanted.
The practical rule: a pink anti-static bag is not a substitute for a shielding bag. Parts that need protection from discharge belong in metallized shielding packaging — during storage, during shipment, and after a bag is opened and resealed.
Materials that work against you
- Ordinary plastic bags and cling film. Excellent charge generators and retainers.
- Bubble wrap and loose foam packing. Popular for mechanical protection and unsuitable as ESD packaging.
- Plain polystyrene. Holds charge well. Conductive or dissipative foam is the alternative.
- Untreated work surfaces and ordinary tape. Common sources in a workshop that is otherwise careful.
The workstation
- A grounded wrist strap, worn properly against the skin, and checked — a strap that has failed open gives a false sense of protection.
- A dissipative work surface connected to the same ground point.
- Grounded tools: soldering iron tips, tweezers, and any powered equipment that touches the part.
- Ionisers where genuinely insulative materials cannot be removed — they neutralise charge that cannot be drained.
- Humidity control. Charge builds far more readily in dry air; keeping the room above roughly 40% relative humidity measurably reduces it.
Handling habits that matter most
- Hold components by the body, never by the leads or contacts.
- Keep parts in their packaging until the moment they are used, and return leftovers to shielding packaging, not to an open bin.
- Do not slide parts across a bench or allow them to tumble in a loose pile.
- Never transfer parts into plain plastic for convenience, even briefly.
- Remember that an assembled board is also a sensitive item — connectors and edge contacts are exposed conductors.
- Treat receiving as part of the chain: packaging that has clearly been opened and repacked is a warning sign in its own right, which our guide to checking components for counterfeits covers.
Storage and shipping
Store semiconductors and moisture-sensitive parts in shielding bags or conductive trays, in a labelled location, with the bag kept closed between uses. Remember that ESD protection and moisture protection are separate requirements and often both apply: a part may need a metallized shielding bag and a moisture barrier with desiccant. Our note on moisture sensitivity and dry packing covers the second requirement.
For shipment, original packaging is almost always the right answer. Where parts must be repacked, use shielding bags sized to the contents, keep parts restrained so they cannot move, and label the package so the next person does not open it casually.
Where ESD control usually breaks down
- Protection applied at the bench but not in stores or at goods-in
- Pink anti-static bags relied on for storage and transit
- Wrist straps worn but never tested
- Parts decanted into plain plastic bins for kitting
- Packaging opened for a partial build and not resealed
- Handling rules written down but not applied to visitors, maintenance or cleaning staff
The last one is not a joke — an ungrounded person reaching into an open bin is exactly the human-body-model event the whole programme exists to prevent.
Sourcing parts that arrive protected
At YILUDA TECH every listed part is 100% original, new and unused, with no refurbished or counterfeit material, held in stock at our Shenzhen warehouse and shipped worldwide by DHL, FedEx or UPS. Incoming inspection and traceability documentation are available on request.
Send the full ordering code with quantity, any packaging requirement and your destination and we will confirm availability, pricing and lead time. Our guides to packaging formats and to date codes and batch numbers cover what to record when goods arrive, and you can browse the full component inventory.