ESD protection hardware is selected against four surface-resistance bands defined across the industry: conductive below 10⁵ Ω, static dissipative 10⁶ to 10⁹ Ω, antistatic 10⁹ to 10¹² Ω, and insulative above 10¹² Ω [S3][S2]. Each band governs a different discharge behavior, and choosing the wrong one either wastes a charge to ground too fast or traps it on the surface long enough to damage components.
The context is the human body model (HBM) device class, which can be destroyed by a discharge as low as 20 V, while walking across a normal floor can lift a person's body voltage above 30,000 V [S3]. Every mat, wrist strap, shoe, garment, and tool that touches an ESDS item has to be specified against a resistance target that fits the EPA's defined control level.
The Four Resistance Bands and What Each One Does
The dissipative band, 10⁶ to 10⁹ Ω, is the engineering center of gravity for ESD work: charges flow to ground slowly enough to avoid a spark, fast enough to clear the surface in well under a second [S3][S7]. The conductive band, anything below 10⁵ Ω, is reserved for grounding hardware and immediate charge removal, since a sub-10⁵ Ω path acts like a direct short and can fault a powered board [S3].
Above 10⁹ Ω the material is no longer dissipative; it is antistatic, slowing tribocharging to roughly 10⁹ to 10¹¹ Ω in typical formulations and 10⁹ to 10¹² Ω at the wider published upper limit [S2]. Above 10¹² Ω the material is an insulator and traps charge, which is the failure mode EPA programs are built to eliminate [S3]. For static-smart floor coverings, ESD S7.1/NFPA 99 Resistance Characterization of Materials locks the working range to 2.5×10⁴ Ω up to 1.0×10⁹ Ω, which is why kV rating alone is not enough to qualify a floor [S5].
Person, Garment, and Tool Targets
ESDA Part 3 sets a single hard limit for the human-plus-garment-plus-cord loop: the total system resistance from operator to ground shall be below 35 megohms (3.5×10⁷ Ω) [S4]. That 35 MΩ ceiling is the upper bound of the dissipative band and is what wrist-strap cords and work-surface mats are measured against during EPA audit, with the typical pass window landing between roughly 10⁶ and 10⁷ Ω for the strap path itself.
For tools, NASA JSC-66552 is more aggressive and caps the resistance from a hand tool's tip to ground at 1.0×10¹ Ω (10 Ω), a level that is essentially a direct ground bond rather than a dissipative path [S1]. Antistatic footwear sits in a different band again, generally 1.0×10⁵ Ω to 1.0×10⁸ Ω, wide enough to bleed body charge but high enough to keep the wearer safe from mains-line faults [S6]. A practical selection rule: choose the band that matches the assembly's HBM/CDM class and the EPA's audit test points, then verify with a surface resistance meter on every shift, not just at install.
Comparing the Main ESD Equipment Types Against Decision Criteria
Wrist straps, work-surface mats, flooring, antistatic footwear, and garments all sit in different sub-bands of the dissipative range, and the choice is driven by four criteria: target resistance, charge-decay time, mechanical wear, and safety. A wrist strap targets roughly 1 MΩ in the cord plus 10⁶ to 10⁸ Ω in the cuff, which gives a sub-100 ms decay to ground and survives daily flexing; a work-surface mat targets 10⁶ to 10⁹ Ω across the surface and is bonded to ground through a 1 MΩ resistor at the mat's snap. ESD flooring (vinyl or carpet tile) is specified per ESD S7.1/NFPA 99 at 2.5×10⁴ to 1.0×10⁹ Ω and trades higher mat cost for whole-room protection [S5]. Antistatic shoes or heel straps target 1.0×10⁵ to 1.0×10⁸ Ω so the operator can walk in and out of an EPA without recalibrating a wrist strap [S6]. Cleanroom garments and smocks target roughly 10¹⁰ to 10¹¹ Ω, accepting a slower decay in exchange for low particle shed, and they are paired with a motor protection relay on any ionizer blower to cut blower power if the ionizer's high-voltage stage faults.
The decision grid is: use a 1 MΩ wrist strap at every static-s bench, a 10⁶–10⁹ Ω mat under each bench, ESD-S7.1 flooring across the EPA, dissipative shoes on every operator, and antistatic (not dissipative) garments in cleanroom and medical packaging areas where the looser 10⁹–10¹¹ Ω band is acceptable [S3][S2][S5][S6].
Standards, Test Methods, and Acceptance Windows
ESD S7.1 / NFPA 99 Resistance Characterization of Materials is the workhorse test method for floors, mats, and work surfaces, with the published acceptable window 2.5×10⁴ Ω to 1.0×10⁹ Ω [S5]. ANSI/ESDA/JEDEC JS-001 and JS-002 govern HBM and CDM device qualification, which is what tells you how sensitive the parts on your bench actually are [S4]. The 35 MΩ operator-to-ground ceiling in ESDA Part 3 is the audit-time pass/fail line, and it is the single number most often missed on a first EPA certification [S4].
For hand tools, NASA-STD-8739 series and JSC-66552 keep the 10 Ω tip-to-ground number in the program, and that limit is checked with a decade resistance box substituted in for the tool to confirm the test set itself reads correctly before each tool audit [S1]. The 10⁹ to 10¹¹ Ω antistatic band is a treated-surface phenomenon, so its resistance drifts with humidity, contamination, and cleaning chemistry, which is why monthly verification, not annual, is the rule on a real production line [S2].
Who This Band Map Is For, and Where It Breaks
This is for electronics assembly, semiconductor back-end, PCB rework, and any EPA that handles HBM-class-1 or class-1A parts (withstand below 250 V), where the dissipative 10⁶ to 10⁹ Ω window is mandatory [S3][S4]. It is also the right map for ATEX zone-classified sites that have to manage ignition risk from static on non-conductive surfaces, and a properly bonded microcomputer protection controller on the ionizer blower is what enforces the upper resistance limit automatically in those zones.
It is not the right map for high-voltage substation work, where the 35 MΩ operator limit is dangerously close to a live-line path, and is not the right map for explosive-munitions lines, where the band tightens to 10⁶ to 10⁸ Ω and any antistatic (10⁹+) garment is non-compliant. The map also breaks at the packaging boundary: shielded bags, pink-poly, and conductive foams live below 10⁵ Ω on purpose to shunt a discharge around the device rather than dissipate it, which is the opposite of what a work-surface mat does [S3][S4].
Selection Checklist and Common Failure Modes
Specify the band, not the brand: 10⁶ to 10⁹ Ω for work surfaces, 1.0×10⁵ to 1.0×10⁸ Ω for operator paths via wrist strap or shoe, 2.5×10⁴ to 1.0×10⁹ Ω for floor, 10⁹ to 10¹¹ Ω only for antistatic (not ESDS-handling) garments, and below 10 Ω tip-to-ground for any powered hand tool [S1][S3][S4][S5][S6]. Verify each path with a protection relay or handheld ohmmeter on install, then re-verify on the EPA's audit cadence, and log the reading against the band window so a drift up into the antistatic range is caught before it becomes a field return. Two trackable signals for the next quarter: the percent of operators whose wrist-strap-plus-cord loop still reads below 35 MΩ at the 30-day audit, and the percent of work surfaces that hold inside 10⁶ to 10⁹ Ω after the third cleaning cycle of the month.
This topic is covered further in AAC vs Fired Clay Brick: Thermal Conductivity Decision Map.