ESD Control — Protected Areas, Grounding and Packaging | Sucatec Knowledge Base

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ESD Control — Protected Areas, Grounding and Packaging

Comprehensive ESD control reference. HBM/CDM sensitivity classifications, ANSI/ESD S20.20 and IEC 61340-5-1:2024 programme requirements, grounding and resistance limits, EPA control items, ionisation, and ESD protective packaging (ANSI/ESD S541).

Fundamentals

What is ESD and Why Does it Matter

Electrostatic Discharge (ESD) is the sudden flow of electric current between objects at different electrostatic potentials. In electronics manufacturing, ESD can damage or destroy semiconductor devices through four primary failure mechanisms: gate oxide rupture, junction damage, metallisation melt and bulk silicon burnout. Damage may be latent (causing premature field failure) or catastrophic (immediate failure). IEC 61340-5-1:2024

Three Discharge Models ANSI/ESDA/JEDEC JS-001

Model	Abbreviation	Circuit Model	Rise Time	Peak Current	What It Represents
Human Body Model	HBM	100 pF capacitor, 1500 Ω series resistor	2–10 ns	~1.3 A at 2000 V	Discharge from a person's fingertip to device leads
Machine Model	MM	200 pF capacitor, 500 nH inductor, ~0 Ω	15–25 ns	~3 A at 200 V	Charged metallic object or equipment discharging to device
Charged Device Model	CDM	Device charges then discharges	<200 ps	Tens of amperes	Device itself is charged and discharges when contacting a conductor

CDM events are the fastest and most destructive per unit energy. Modern semiconductor devices with gate oxides <5 nm are particularly vulnerable to CDM damage. HBM remains the most widely used qualification model.

ESD Damage Categories

Category	Description	Detection	Risk
Catastrophic	Immediate hard failure — device non-functional after ESD event	Detectable at test	High — caught in production
Latent degradation	Device passes initial test but has weakened junction or oxide — fails prematurely in field	Very difficult to detect	Very high — undetected cost, warranty returns
Upset / soft error	Temporary functional change — device recovers on reset; no permanent damage	Data error or reset	Moderate — field reliability impact

Industry studies estimate that 20–30% of all ESD-related failures are latent. Latent damage is particularly costly because it passes production test and causes field failures.

ANSI/ESDA/JEDEC JS-001 / IEC 61340-5-1

ESD Sensitivity Classification

ESD sensitivity levels define the voltage threshold below which a component is susceptible to damage. Components are classified using standardised models. The HBM classification is the most universally applied. Lower class numbers indicate higher sensitivity and therefore greater handling risk. ANSI/ESDA/JEDEC JS-001-2023 ANSI/ESD STM5.1

HBM Classification — ANSI/ESDA/JEDEC JS-001

HBM Class	Voltage Range	Handling Risk	Typical Device Types
Class 0A	< 125 V	Extreme	Advanced CMOS logic, deep-submicron process nodes (<65 nm)
Class 0B	125 V to < 250 V	Very high	Sub-100 nm CMOS, MEMS, RF transistors
Class 1A	250 V to < 500 V	High	MOSFETs, GaAs ICs, precision op-amps, some memory
Class 1B	500 V to < 1000 V	High	Most CMOS logic, microcontrollers, linear ICs
Class 1C	1000 V to < 2000 V	Moderate	Bipolar transistors, standard logic, EPROMs
Class 2	2000 V to < 4000 V	Moderate	Most jellybean transistors, standard TTL
Class 3A	4000 V to < 8000 V	Lower	Power transistors, many through-hole devices
Class 3B	≥ 8000 V	Low	Robust power devices, most passive components

ANSI/ESDA/JEDEC JS-001-2023 is the current HBM standard. Components below Class 1C (< 2000 V HBM) require full EPA handling procedures. Classes 0A and 0B require additional controls beyond standard S20.20.

CDM Classification — ANSI/ESD STM5.3.1

CDM Class	Voltage Range	Notes
CDM Class C1	< 125 V	Highest sensitivity; requires careful automated handler grounding
CDM Class C2	125 V to < 250 V	Very sensitive; review handler contact points
CDM Class C3	250 V to < 500 V	Sensitive; standard EPA plus CDM controls
CDM Class C4	500 V to < 1000 V	Moderate
CDM Class C5	1000 V to < 2000 V	Lower risk
CDM Class C6	≥ 2000 V	Standard handling generally sufficient

CDM sensitivity is not the same as HBM sensitivity for the same device. A device may be Class 2 HBM but Class C1 CDM. Both models should be evaluated for critical components.

ANSI/ESD S20.20 / IEC 61340-5-1

ESD Control Programme Requirements

An ESD Control Programme defines the administrative and technical framework for protecting ESD-sensitive (ESDS) items throughout manufacture, assembly, test, inspection, packaging and transport. Both ANSI/ESD S20.20-2007 (US) and IEC 61340-5-1:2024 (international) require a documented, maintained programme. ANSI/ESD S20.20 IEC 61340-5-1:2024

Programme Element	Requirement	Standard Reference
ESD Control Programme Plan	Written document defining scope, technical requirements, products handled and most sensitive item class	S20.20 §7.1 / IEC §5
ESD Programme Manager	Named individual responsible for compliance verification	S20.20 §6.2
Training Plan	Initial and recurrent training for all personnel handling ESDS items; records maintained	S20.20 §7.2 / IEC §6
Compliance Verification Plan	Defines test methods, measurement limits and frequency for all technical requirements	S20.20 §7.3 / IEC §7
Grounding / Equipotential Bonding	All conductors and personnel bonded to common ground point within EPA	S20.20 §8.1
Personnel Grounding	Wrist strap or footwear/flooring system when handling ESDS items	S20.20 §8.2 / IEC §8.3
ESD Protected Area (EPA)	Designated area with defined ESD controls for all unpackaged ESDS handling	S20.20 §8.3 / IEC §8.4
Packaging	ESD protective packaging inside and outside EPA; per ANSI/ESD S541	S20.20 §8.4 / IEC §8.6
Marking	ESDS marking on components, packaging and assembly areas where required	S20.20 §8.5 / IEC §8.7
Tailoring	Documented justification where requirements are adjusted for specific application	S20.20 §6.3

IEC 61340-5-1:2024 (third edition, published May 2024) aligns closely with ANSI/ESD S20.20. The 2024 IEC update clarifies insulator handling requirements and updates the definition of insulators as materials with resistance ≥1×10¹¹ Ω.

ANSI/ESD S6.1 / ANSI/ESD S20.20 Table 1

Grounding and Equipotential Bonding Requirements

All conductors within the EPA — including workbenches, equipment chassis, shelving, carts and personnel — must be connected to a common ground point. This equipotential bonding eliminates potential differences that can cause electrostatic discharge. Ground connections must be verified periodically. ANSI/ESD S6.1

Technical Requirement	Implementing Process	Test Method	Required Limit
Equipment Grounding Conductor	Connect all equipment chassis to building protective earth	ANSI/ESD S6.1	< 1.0 Ω impedance
Auxiliary Ground	Common point ground bar or ground bus in EPA	ANSI/ESD S6.1	< 25 Ω to equipment grounding conductor
Equipotential Bonding	Resistance between any ESD technical element and common connection point	ANSI/ESD S6.1	< 1.0 × 10⁹ Ω

Source: ANSI/ESD S20.20-2007 Table 1. An auxiliary ground provides a low-impedance path for ESD energy dissipation. All ESD ground connections should be verified at initial installation and periodically thereafter per the Compliance Verification Plan.

Personnel Grounding — ANSI/ESD S20.20 Table 2 / IEC 61340-5-1

Personnel Grounding Method	Product Qualification Test Method	Required Limit (Product Qual.)	Compliance Verification	Required Limit (Verification)
Wrist Strap System	ANSI/ESD S1.1 §5.11	< 3.5 × 10⁷ Ω total system	ESD TR53 Wrist Strap Section	< 3.5 × 10⁷ Ω
Flooring/Footwear — Method 1 (combined)	ANSI/ESD STM97.1	< 3.5 × 10⁷ Ω (person through footwear + flooring)	ESD TR53 Flooring Section	< 3.5 × 10⁷ Ω
Flooring — Method 2 (seated)	ANSI/ESD STM97.1	< 1.0 × 10⁹ Ω	ESD TR53 Flooring Section	< 1.0 × 10⁹ Ω
Footwear — Method 2 (standing)	ANSI/ESD STM97.2	Body voltage < 100 V	ESD TR53 Footwear Section	< 1.0 × 10⁹ Ω

Wrist straps must be worn for all seated EPA operations. For standing operations, a wrist strap or validated footwear/flooring system may be used. Wrist strap cords must contain a 1 MΩ current-limiting resistor (0.8–1.2 MΩ) to protect the wearer.

Wrist Strap Construction Requirements ANSI/ESD S1.1

Component	Required Limit	Notes
Cord resistance (interior)	< 1.0 × 10⁵ Ω	Low resistance inner conductor
Cuff resistance (exterior)	> 1.0 × 10⁷ Ω	Insulating outer surface prevents shock
Cord bending life	>16,000 flex cycles	Mechanical durability requirement
System resistance (person + strap)	< 3.5 × 10⁷ Ω	Total path including skin resistance
Daily verification	ESD TR53 / continuous monitor	Verify before each use or use continuous monitor

Continuous wrist strap monitors provide real-time verification and are preferred over daily manual testing for high-volume production. Monitors detect both open-circuit and out-of-range resistance conditions.

ANSI/ESD S20.20 Table 3

EPA ESD Control Items — Requirements and Limits

Within an ESD Protected Area (EPA), ESD control items must meet qualification and ongoing compliance verification limits. Items selected for the ESD Control Programme become mandatory requirements. The table below covers the most common EPA control items. ANSI/ESD S20.20 §8.3

ESD Control Item	Product Qualification Test Method	Required Limit (Qualification)	Compliance Verification Method	Required Limit (Verification)
Worksurface	ANSI/ESD S4.1 and/or STM4.2	< 1 × 10⁹ Ω and/or < 200 V	ESD TR53 Worksurface Section	< 1 × 10⁹ Ω resistance to ground
Worksurface — charge dissipation	ANSI/ESD STM4.2	< 200 V decay in ≤2 s	ESD TR53	< 200 V
Flooring	ANSI/ESD S7.1	< 1 × 10⁹ Ω	ESD TR53 Flooring Section	< 1 × 10⁹ Ω
Footwear	ANSI/ESD STM9.1	< 1 × 10⁹ Ω	See Table 2 (Personnel Grounding)	See Table 2
Foot Grounders	ESD SP9.2	< 1 × 10⁹ Ω	See Table 2	See Table 2
Seating	ANSI/ESD STM12.1	< 1 × 10⁹ Ω	ESD TR53 Seating Section	< 1 × 10⁹ Ω resistance to ground
EPA Garments — Static Control	ANSI/ESD STM2.1	< 1 × 10¹¹ Ω	ESD TR53 Garments Section	< 1 × 10¹¹ Ω
EPA Garments — Groundable	ANSI/ESD STM2.1	< 1 × 10⁹ Ω	ESD TR53 Garments Section	< 1 × 10⁹ Ω
Groundable Garment System	ANSI/ESD STM2.1	< 3.5 × 10⁷ Ω (total system)	ESD TR53 Garments Section	< 3.5 × 10⁷ Ω
Shelving	ANSI/ESD S4.1	< 1 × 10⁹ Ω	ESD TR53 Worksurface Section	< 1 × 10⁹ Ω resistance to ground
Mobile Equipment (work surfaces)	ANSI/ESD S4.1	< 1 × 10⁹ Ω	ESD TR53 Mobile Equipment Section	< 1 × 10⁹ Ω resistance to ground
Ioniser — workstation/bench	ANSI/ESD STM3.1	Offset voltage < ±50 V; discharge time user defined	ESD TR53	Offset < ±50 V
Ioniser — room system	ANSI/ESD STM3.1	Offset voltage < ±150 V; discharge time user defined	ESD TR53	Offset < ±150 V
Continuous Monitor (wrist strap)	User/manufacturer defined	User defined	ESD TR53 Continuous Monitors	Manufacturer defined

Source: ANSI/ESD S20.20-2007 Table 3. Items in this table are optional for inclusion in an ESD programme — however, once selected, their limits become mandatory requirements. Periodic re-verification frequency must be defined in the Compliance Verification Plan.

ANSI/ESD S20.20 §8.3 / ANSI/ESD STM3.1

Handling Insulators and Ionisation

Non-conductors (insulators) cannot be grounded and will retain electrostatic charge indefinitely. Common insulators found in EPAs include PCB substrate material, standard plastic cups, food packaging, personal items and certain device packages. Insulators must be assessed and controlled. ANSI/ESD S20.20 §8.3 IEC 61340-5-1:2024

Insulator Handling Approach	Requirement	Notes
Identify process-required insulators	Document in ESD Control Programme Plan	Distinguish between necessary and non-essential insulators
Non-essential insulators	Remove from EPA or keep ≥30 cm (12 in) from ESDS items	Coffee cups, food wrappers, personal items, standard plastics
Process-required insulators with field > 2000 V/in	Option A: Maintain ≥30 cm separation from ESDS items	Measure field with electrostatic fieldmeter
Process-required insulators with field > 2000 V/in	Option B: Use ionisation to neutralise charge	See ioniser limits in EPA control items table
IEC 61340-5-1:2024 insulator definition	Materials with resistance ≥ 1.0 × 10¹¹ Ω	Updated definition in 2024 revision

Ionisers generate balanced positive and negative ions to neutralise charge on insulators. Proper placement and calibration is critical — an out-of-balance ioniser can induce charge rather than neutralise it. Ioniser offset voltage must not exceed ±50 V for workstation units.

Ioniser Types and Applications ANSI/ESD STM3.1 ANSI/ESD SP3.3

Ioniser Type	Coverage	Discharge Time	Typical Application
AC Bench Top (overhead)	Single workstation — 0.5–1.5 m radius	5–30 s at 30 cm	ESD workstation, rework bench
Pulsed DC Bench Top	Single workstation — better balance than AC	2–10 s at 30 cm	Precision assembly, test
Room Ionisation System	Full room, plenum or HVAC-mounted	60–120 s for room volume	Clean rooms, automated assembly, wafer fab
Nitrogen Ionisation Gun	Localised — direct application	<2 s at contact	Wafer handling, bare die, ultra-sensitive devices
Air-assisted Ioniser (blower)	Directed air stream — 0.5–2 m effective	3–15 s at 60 cm	SMT lines, inspection areas

Ioniser offset voltage and discharge time must be verified periodically per ANSI/ESD SP3.3. Calibration targets and calibrated plate monitors are required. Minimum verification frequency must be stated in the Compliance Verification Plan.

ANSI/ESD S541

ESD Protective Packaging

ESD protective packaging prevents charge generation and transfer to ESDS items during storage and transport. ANSI/ESD S541 (current edition: 2019) defines required packaging properties inside and outside the EPA. ANSI/ESD S541-2019

Packaging Location	Required Properties	Packaging Type Examples
Inside EPA only — handling	Low-charging and conductive or dissipative	Pink poly bags, dissipative trays, conductive totes, bubble-in-bag
Outside EPA — storage and transport	Low-charging, conductive/dissipative PLUS electrostatic discharge shielding	Metal-in shielding bags, Faraday cage bags, shielded trays
Moisture-sensitive devices (additional)	Moisture barrier bag (MBB) + desiccant + humidity indicator card (HIC)	Per IPC/JEDEC J-STD-033

Discharge shielding specification: < 20 nanojoules (nJ) per ANSI/ESD S541-2018/2019 (reduced from 50 nJ in earlier editions). The shielded bag construction typically uses a metal vapour deposition layer between polyester outer film and polyethylene inner film.

Packaging Material Type	Surface Resistance	Volume Resistance	Property
Conductive	< 1.0 × 10⁴ Ω/sq	< 1.0 × 10⁴ Ω-cm	Fastest charge dissipation; used for Faraday cage bags
Dissipative	1.0 × 10⁴ to 1.0 × 10¹¹ Ω/sq	1.0 × 10⁴ to 1.0 × 10¹² Ω-cm	Controlled dissipation; trays, pink poly, foam
Low-charging / antistatic	≤ 2.0 × 10¹¹ Ω/sq (triboelectric limit)	—	Reduces charge generation on contact
Shielding (metal-in bag)	Outer: dissipative; Inner: conductive or dissipative	—	Provides Faraday effect — blocks external fields

Test method for surface resistance: ANSI/ESD STM11.11. Volume resistance: ANSI/ESD STM11.12. Low-charging property measured by triboelectric charge generation test.

ESD Packaging Markings ANSI/ESD S20.20 §8.5 IEC 61340-5-1

Symbol	Name	Meaning
ESD Susceptibility Symbol (hand with lightning bolt in triangle)	ESDS symbol	Item is ESD sensitive — handle with ESD precautions
ESD Protective Symbol (hand with lightning bolt in circle)	ESD protective material	Packaging or surface provides ESD protection
ANSI/ESD S8.1	Label standard	Defines size, colour and artwork for ESD labels on bags and boxes

The ESD susceptibility symbol (IEC 60417-5134) must appear on packaging for ESDS items. The ESD protective symbol (IEC 60417-5335) indicates the packaging provides ESD protection. Both symbols are defined in ANSI/ESD S8.1 and IEC 61340-5-1 Annex A.

References

Standards Cited

ANSI/ESD S20.20-2007 — ESD Control Programme IEC 61340-5-1:2024 — ESD Protection, General Requirements (Edition 3) IEC TR 61340-5-2 — ESD Protection, User Guide ANSI/ESDA/JEDEC JS-001-2023 — HBM ESD Sensitivity Testing ANSI/ESD STM5.1 — HBM Sensitivity Test Method ANSI/ESD STM5.3.1 — CDM Sensitivity Test Method ANSI/ESD S1.1 — Wrist Straps ANSI/ESD S4.1 — Worksurfaces ANSI/ESD S6.1 — Grounding ANSI/ESD S7.1 — Floor Materials ANSI/ESD STM2.1 — Garments ANSI/ESD STM3.1 — Ionisation ANSI/ESD SP3.3 — Periodic Verification of Air Ionisers ANSI/ESD STM9.1 — Footwear ANSI/ESD STM12.1 — Seating ANSI/ESD STM97.1 — Floor and Footwear Resistance ANSI/ESD S541-2019 — ESD Protective Packaging ANSI/ESD STM11.11 — Surface Resistance ANSI/ESD STM11.12 — Volume Resistance ANSI/ESD S8.1 — ESD Labels and Symbols ESD TR53 — Compliance Verification of ESD Protective Equipment IPC/JEDEC J-STD-033 — Moisture Sensitive Devices MIL-STD-1686 — ESD Control (US Military)