ANSI ESD-S20.20-2021-EN.pdf - 第16页

ANSI/ESD S20.20- 2021 8 Table 3. EPA ESD Control Items Technical Requirement ESD Control Item Product Qualification Compliance Verificatio n Test Method Required Limit(s) (8) Test Method Required Limit(s) EPA Worksurface…

ANSI/ESD S20.20-2021

the reading shall be less than 125 volts when measured at the meter's stipulated measuring

distance.

• For any process essential insulators located more than 25 mm, but less than 300 mm from an

unprotected ESDS item, the voltage on the surface of the insulator shall be less than 2000 volts

when measured with a non-contact electrostatic voltmeter. When using an electrostatic field

meter, the reading shall be less than 2000 volts when measured at the meter's stipulated

measuring distance.

NOTE: Insulators should be measured after normal handling that could occur during the processing of ESDS

items with materials in use in the EPA. The insulators should not be artificially charged. See ESD TR20.20 for

more information.

NOTE: See ESD TR20.20 for more information on insulators and charge mitigation techniques.

NOTE: The accurate measurement of electrostatic fields requires that the person making the measurement

is familiar with the operation of the measuring equipment. An electrostatic field meter responds to the

electrostatic field emanating from a charged surface and converts the field into a voltage when the meter is

positioned at the meter's stipulated distance. When measuring relatively large conductors, the electrostatic

field meter reading is the actual voltage on the conductor when measured at the meter's stipulated measuring

distance. However, for non-uniformly charged insulators, the voltage indicated by the field meter (when

measured at the meter's stipulated measuring distance) is an average of the electrostatic field strengths of the

charged insulator.

NOTE: If a non-contact electrostatic voltmeter is used, care must be taken to ensure the non-contact

electrostatic voltmeter's spot resolution (the smallest measurement area that the meter can resolve) is smaller

than the insulator being measured. For a non-contact electrostatic voltmeter, this is a combination of aperture

size and distance to the object. It is recommended to measure the item at the smallest distance stated by the

manufacturer.

8.3.2 Isolated Conductors

If a conductor that cannot be grounded or equipotentially bonded comes into contact with an ESDS

item, the process shall ensure that the potential between the isolated conductor and ground is

between -35 volts and +35 volts.

For an isolated conductor that does not come into contact with an ESDS item, the requirements for

insulators in Section 8.3.1 shall be met.

NOTE: For accurate measurements, it is recommended to use a high impedance contact voltmeter. If a non-

contact electrostatic voltmeter or electrostatic field meter is used, care must be taken to ensure the spot

resolution (the smallest measurement area that the meter can resolve) is smaller than the isolated conductor

being measured. For a non-contact electrostatic voltmeter, this is a combination of aperture size and distance

to the object. It is recommended to measure the item at the smallest distance stated by the manufacturer.

ANSI/ESD S20.20-2021

Table 3. EPA ESD Control Items

Technical

Requirement

ESD Control

Item

Product Qualification

Compliance Verification

Test Method

Required

Limit(s)

(8)

Test Method

Required

Limit(s)

EPA

Worksurface

(9)

ANSI/ESD

STM4.1

Point to Point

< 1.0 x 10

ohms

ESD TR53

Worksurface

Section

Point to Ground

< 1.0 x 10

ohms

Point to

Groundable Point

< 1.0 x 10

ohms

Wrist Strap

ANSI/ESD S1.1

0.8 x 10

1.2 x 10

ohms

For compliance verification of a

Wrist Strap System, see Table 2.

Wristband

ANSI/ESD S1.1

Interior

< 1.0 x 10

ohms

Exterior

> 1.0 x 10

ohms

Personnel

Ground Wrist

Strap

Connection

(non-

monitored)

ANSI/ESD S6.1

Point to

Ground

(10)

< 2 ohms

ESD TR53

Grounding/

Equipotential

Bonding

Systems

Section

Point to

Ground

(10)

< 2 ohms

Continuous

Monitors

User-defined

ESD TR53

Continuous

Monitors

Section

Manufacturer

defined

Footwear

ANSI/ESD

STM9.1

Point to

Groundable Point

< 1.0 x 10

ohms

For compliance verification of the

Footwear/Flooring System, see

Table 2.

Foot

Grounders

ANSI/ESD

SP9.2

Point to

Groundable Point

< 1.0 x 10

ohms

Flooring

ANSI/ESD

STM7.1

Point to Point

< 1.0 x 10

ohms

Point to

Groundable Point

< 1.0 x 10

ohms

Seating

ANSI/ESD

STM12.1

Point to

Groundable Point

< 1.0 x 10

ohms

ESD TR53

Seating

Section

Point to Ground

< 1.0 x 10

ohms

Table 3 continued next page.

For standards that have multiple resistance test methods, these limits apply to all methods.

Due to a wide variety of applications for worksurfaces, specific requirements that could be broadly applied

are difficult to determine. If there is a concern for CDM failures, then a lower limit of 1.0 x 10

ohms for point

to point and point to groundable point should be considered.

If there is a resistor in line, then the limit must be adjusted to less than 5.0 x 10

ohms.

ANSI/ESD S20.20-2021

Technical

Requirement

ESD Control

Item

Product Qualification

Compliance Verification

Test Method

Required

Limit(s)

(8)

Test Method

Required

Limit(s)

EPA

Ionization

ANSI/ESD

STM3.1

Discharge Time

User-defined

ESD TR53

(11)

Ionization

Section

Discharge Time

User-defined

Offset Voltage

(Peak)

-35 volts <

Voffset

< 35 volts

Offset Voltage

(Peak)

-35 volts< Voffset

< 35 volts

Shelving

(9)

(When used

to store

unprotected

ESDS items)

ANSI/ESD

STM4.1

Point to Point

< 1.0 x 10

ohms

ESD TR53

Worksurface

Section

Point to Ground

< 1.0 x 10

ohms

Point to

Groundable Point

< 1.0 x 10

ohms

Mobile

Equipment

(9)

(Working

Surfaces)

ANSI/ESD

STM4.1

Point to Point

< 1.0 x 10

ohms

ESD TR53

Worksurface

Section

Point to Ground

< 1.0 x 10

ohms

Point to

Groundable Point

< 1.0 x 10

ohms

Electrical

Soldering/

Desoldering

Hand Tools

ANSI/ESD

S13.1

Tip to Ground or

Groundable Point

< 2.0 ohms

ESD TR53

Electrical

Soldering/

Desoldering

Hand Tools

Section

Tip to Ground or

Groundable Point

< 10 ohms

Tip Voltage

< 20 millivolts

Tip Leakage

< 10 milliamps

Static Control

Garment

ANSI/ESD

STM2.1

Point to Point

< 1.0 x 10

ohms

ESD TR53

Static Control

Garment

Section

Point to Point

< 1.0 x 10

ohms

Groundable

Static Control

Garment

ANSI/ESD

STM2.1

Point to Point and

Point to

Groundable Point

< 1.0 x 10

ohms

ESD TR53

Groundable

Static Control

Garment

Section

Point

to Groundable

Point

< 1.0 x 10

ohms

For additional information on periodic testing of Ionizers, see ANSI/ESD SP3.3.