3.4 Ionization & Insulator Control

Grounding straps and conductive floors have a fatal physical limitation: they only workswork foron conductorsconductors. They are chemically incapable of draining charge from insulators (plastics, epoxy, glass). InsulatorsWhen (an ungrounded insulator—like a plastic housings, connector bodies,housing or a circuit board fiberglass)substrate—accumulates charge, it creates an electrostatic field. This field can induce voltage onto nearby conductive traces without contact (Field-Induced Charging), leading to CDM failures the moment the board touches a grounded tool. Ionization is not optional "air blowing"; it is the only way to neutralize insulators.

Insulator Management Strategy

You cannot beeliminate grounded;all chargeinsulators stays(the PCB itself is one). You must manage the risk based on themproximity.

until

Decision itLogic: naturallyThe decays30 (hours/days)cm orRule

discharges into a sensitive component.

Active Neutralization (Ionization)

1. Requirement:IF Ionizersthe (overheadinsulator fansis or"Process point-of-use snakes) are mandatory at stations where essential insulators are handledEssential" (e.g., finalconnector assemblybodies, intoPCB plasticfiberglass, cases).specialized jigs) → THEN Neutralize with Active Ionization.
2. PerformanceIF Limits:the insulator is "Non-Essential" (e.g., coffee cups, scotch tape, standard paperwork, plastic binders) → THEN Ban from the EPA entirely.
   • Decay Time:Constraint: 1000V to 100V in < 2 seconds.
   • Offset Voltage (Balance): The ionizer must produceMaintain a balanced stream (± 35V). If the ionizer becomes unbalanced, itstrict charges> 30 cm theexclusion product.

zone

Packagingfrom & Handling

• Shielding:any ESDS (Electrostatic Discharge Sensitive) itemscomponent.

must

Active Neutralization (Ionization)

Ionizers flood the air with positive and negative ions, neutralizing any static charge on surfaces that cannot be transportedgrounded.

in

Selection Logic

• Overhead Blowers: Use for general workbench coverage.
  • Risk: Airflow blockage. Ensure objects don't block the "line of sight" to the product.
• Point-of-Use (Snake) Ionizers: Use for focused, high-static activities (e.g., inside a wave solder machine or automated tape-and-reel).
• Ionizing Guns: Use for cleaning dust off optics or sensors.
  • Warning: Standard compressed air generates massive static friction. Metal-In Shielding BagsOnly use ionized air guns.

Pro-Tip: Ionizers are not "set and forget." Emitter points erode and collect silica/dust, causing the electrical balance to drift. A dirty ionizer often becomes a static generator, pumping thousands of volts of positive charge onto your product.

Packaging & The "Faraday Cage"

Protection during transport relies on creating a shield that external fields cannot penetrate.

Material Standards

• Silver "Metal-In" Bags (Silver).Shielding): * Requirement: Mandatory for all PCBAs and sensitive components moving outside the EPA.
  • Physics: The metal layer creates a Faraday Cage, blocking external electrostatic fields.
• Pink Poly Bags (Dissipative):
  • Usage: bags are onlyOnly for "Low Risk" items (screws, brackets, non-sensitive items;hardware).
  • Limitation: theyPink dopoly notis shieldNOT a shield. It merely prevents the bag itself from generating charge. It offers zero protection against external fields.

Transport Logic

• Carts:IF Transportmoving cartsmaterial on a cart → THEN The cart must havebe electrically bonded to the floor via drag chains or conductive casters to maintain electrical contact withcasters.
• IF the ESDcart floor.wheels are dirty → THEN The cart is an isolated floating conductor. Clean wheels monthly.

Final Checklist

Control Parameter	Specification / Limit	Maintenance IntervalFrequency	Owner
Ionizer Decay Time	1000V to 100V in < 2.0 Seconds	Quarterly	Quarterly CalibrationMaintenance
Ionizer Balance	Offset Voltage ± 35 Volts	Quarterly	Quarterly CalibrationMaintenance
ShieldingProcess BagsInsulators	Metal-InNeutralized Required(Ionized) or > 30 cm away	Visual CheckDaily	Operations
CartMobile GroundingCarts	Ground Path < $1.0 \timesx 10^9$9 OhmsΩ	Monthly	ESD ProbeLead
Packaging	Shielding (Silver) for all actives	Spot Check	Logistics

Next Step: Would you like me to proceed to 3.5 ESD Compliance Verification & Auditing to finalize the ESD Program chapter?