5.3 ESD Control Program

Electrostatic discharge is invisible, unpredictable, and often devastating to sensitive electronics, making control programs as critical as solder paste or pick-and-place accuracy. By defining EPAs with clear boundaries, tying every surface and operator to a common ground, and shielding components in transit, factories create an environment where static has nowhere to strike. Ionizers handle the exceptions—plastics and films that cannot be grounded—while lightweight audits keep the discipline alive without slowing production. With these measures in place, static electricity is reduced to background noise, never a hidden variable in product reliability.

5.3.1 Purpose & scope

Keep charge off parts and people from dock to feeder. This program defines ESD Protected Areas (EPAs), how we ground people and hardware, when we ionize air, and which containers are safe. It pairs with 5.1 (IDs), 5.2 (areas), and 5.4 (MSDs).

5.3.2 EPAs (boundaries you can see)

Where: Component Store (CMP-STORE), Line-Side Supermarket (LINE-SMKT), kitting benches, feeder banks, rework benches, test/flash where boards are exposed.
Boundary: Yellow/black EPA floor tape + sign (“EPA—ESD Controls Required”).
Rule: Inside EPA: grounded people, grounded surfaces, approved containers. Leaving EPA: parts must be inside shielding packaging.

5.3.3 Grounding architecture (the quiet backbone)

Common point ground (CPG): Every station mat, tool ground, and monitor ties to the same CPG lug; lugs bond to facility ground.
Continuity: Shelves, carts, and racks have visible ground straps; verify continuity monthly.
Workstation monitors: Continuous wrist-strap/mat monitors preferred at high-use benches.

5.3.4 People grounding (entry checks that take seconds)

Default: Wrist strap at benches; ESD footwear + ESD floor when walking/handling totes.
Test at entry: Use the combo tester; pass sticker per shift.
- Wrist strap: pass within your site limits (typical testers use ~0.8–10 MΩ window).
- Footwear/floor: both feet pass within site limits (commonly up to 100 MΩ).
Visitors: Use heel straps in EPAs; supervised handling only.
Exceptions: During Hipot/safety tests (Part II), straps off by procedure; use insulating mats/cages instead.

5.3.5 Workstations, tools & surfaces (what “ESD-safe” really means)

Mats & tabletops: Dissipative range; bonded to CPG; clean with approved solution.
Soldering irons & tweezers: ESD-safe models, tip ground verified quarterly.
Hand tools: Dissipative grips; no raw vinyl or fuzzy synthetics.
Carts & shelves: Metal or dissipative laminate; no bare wood/cardboard touching components.

5.3.6 Materials handling & packaging (pick the right container)

Use case	Accept	Reject
Move parts between EPAs	Shielding bags (metal-in), shielding totes with lids	Pink bags alone; bubble wrap; grocery totes
Inner pouch inside shielding	Pink/clear dissipative bags	Plain PE bags
Long store on racks	Shielding bags in closed totes; labels outside	Open trays; exposed reels
Paperwork	Dissipative document sleeves; clip to tote	Loose paper on mats
Labels	ESD-safe stock; don’t cover HIC/UID	Vinyl stickers on components

Rule of thumb: If it leaves an EPA or passes under an ionizer, shield it.

5.3.7 Ionization (neutralize charges you can’t ground)

When: Plastic enclosures, lens films, label liners, tray transfers, or dry winter air cause nuisance zaps or cling.
Where: Point-of-use ionizers above benches; overhead bars over conveyors.
Care: Clean emitter pins monthly; verify balance/decay quarterly (target ±50 V balance and fast decay per your site spec). Aim airflow across the work, not into trays.

5.3.8 Simple audits that stick (lightweight, regular)

Daily: Wrist-strap tester works; benches have pass stickers; mats clean; totes closed.
Weekly: Spot-check two carts/shelves for ground; wipe ionizer grills; log a reading.
Monthly: Mat resistance & cart continuity form; dry-cabinet RH cross-check (5.2).
Quarterly: Ionizer balance/decay check; solder station tip-to-ground check.

Store results at the cell PC or area binder; green tile on the dashboard means “on time.”

5.3.9 Acceptance cues (fast table)

Check	Accept	Reject
Entry control	Everyone has pass sticker this shift	No tester or expired stickers
People grounding	Straps at benches; heel/foot straps over ESD floors	Bare shoes; strap clipped to chair
Station ground	Mat to CPG, monitor OK	Dangling cords; no CPG tag
Containers	Shielding for travel; pink only as inner	Pink bag carried through the aisle
Ionizers	Clean, blowing across work; in date	Dusty, off, or aimed into trays
Paper & labels	In dissipative sleeves; ESD labels	Static-cling docs on mats

5.3.10 Common traps → smallest reliable fix

Trap	Symptom	First move
Pink bag becomes the tote	Zaps between areas	Shielding bag/tote for any move
“Strap nearby”	Intermittent fails at rework	Continuous monitors; daily tester gate
Chair or cart not bonded	Random AOI false calls	Add ground strap; monthly continuity log
Dirty ionizer	Parts cling; dust on optics	Clean pins/grills; add monthly reminder
Bubble wrap in kits	Popping on open	Replace with shielding foam or bags
Paper piles on mats	Crackles when lifted	Use dissipative sleeves or clipboards

5.3.11 Pocket checklists

Starting a shift

Pass sticker from combo tester (strap + footwear)
Bench monitor green; mat clean and grounded
Shielding totes/bags ready; paperwork in sleeves

Moving parts

Inside shielding before leaving EPA
Totes closed; UID visible (5.1)
No raw plastics or bubble wrap

Weekly quick audit

Two carts/shelves ground-checked
Ionizer wiped; airflow verified
Dry-cab RH seen ≤10% (see 5.2)

Consistent grounding, shielding, and auditing transform ESD from a lurking threat into a controlled constant. This discipline protects components from silent damage, stabilizes yields, and ensures finished products reach the field as robust as designed.