6.5 ESD Control Program

Electrostatic Discharge (ESD) is the silent assassin of electronics. It is invisible, audible only at thousands of volts, and often causes "latent defects"—damage that passes factory testing but causes the product to fail in the customer's hands weeks later. The warehouse is the highest-risk environment for ESD because components are constantly handled, moved, and repackaged.

Treat the warehouse as a strict Electrostatic Protected Area (EPA). ESD control is not a "quality department" task; it is a mandatory handling protocol for every person who touches stock.

The EPA Boundary & Infrastructure

You must define exactly where safe handling begins and ends.

• The Boundary: Clearly mark the EPA entrance with yellow/black tape and signage.
  • Inside EPA: Grounding is mandatory. All surfaces (shelves, carts, tables) must be dissipative and grounded to Earth.
  • Outside EPA: Components must be fully enclosed in ESD Shielding (Metallized) bags.
• Flooring & Mats:
  • Use ESD-safe flooring or conductive mats at all standing workstations (Receiving, Kitting).
  • Rule: If a cart moves parts between zones, the cart wheels must be conductive, or the operator must use a drag chain.

Operator Discipline & Mandatory Checks

Equipment is useless if the operator is isolated from ground.

• Daily Testing: Every operator must test their wrist strap and/or footwear before entering the EPA.
  • If Test = PASS → Entry allowed. Log result.
  • If Test = FAIL → Stop. Replace strap or clean shoes. Do not enter.
• Continuous Monitoring: For stationary workstations (kitting tables), use continuous monitors that alarm immediately if the ground connection breaks.
• Clothing: Smocks must be buttoned. Synthetic fibers (fleece/polyester) generate massive charges; cover them completely.

Packaging Rules: The Hierarchy of Protection

Not all "static bags" are created equal. Understand the physics to avoid killing parts.

1. Metallized Shielding Bags (Silver):
   • Function: Faraday Cage. Blocks external fields.
   • Use: Mandatory for transporting parts outside the EPA or between buildings.
2. Dissipative Poly (Pink/Blue):
   • Function: Low charging. Does not block external fields.
   • Use: Acceptable only inside the EPA for temporary handling.
   • Warning: Pink poly relies on chemical additives that evaporate. It has a shelf life (typ. 1 year). If it looks "dry" or old, throw it away.
3. Insulative Materials (The Enemy):
   • Examples: Standard clear plastic bags, styrofoam peanuts, clear bubble wrap, vinyl binders, scotch tape.
   • Rule: Strictly Forbidden within 30cm of any open electronic component. These materials generate fields that can destroy a chip without even touching it.

Process Integration

Integrate ESD habits into the workflow, not as an afterthought.

• Receiving:
  • Do not slice open shielding bags at the receiving dock just to "count the parts" unless the workstation is grounded.
  • If a supplier ships sensitive parts in standard bubble wrap → NCR/Rejection. The parts are already suspect.
• Picking & Put-away:
  • Never transport a reel or tray "naked" on a cart. It must be in a container (tote or bag).
  • If breaking a pack → Then reseal the remaining quantity in an ESD-safe bag immediately.
• Kitting:
  • Kitting implies removing protection. Ensure the Kit Cart itself is an EPA (conductive shelves/wheels).
  • Do not tape kit instructions to the reel using standard office tape.

The "Suspect Exposure" Rule

Define the consequence of protocol failure.

• Trigger: Component found in clear plastic, handled by ungrounded personnel, or stored near high-voltage sources (CRT monitors, unshielded transformers).
• Action:
  1. Quarantine immediately.
  2. Tag as "ESD Suspect."
  3. Disposition: Generally Scrap. Testing for ESD latent damage is expensive and often destructive. It is cheaper to buy a new reel than to risk a field failure.

Final Checklist