ANSI/ESD S20.20 standard v. EAI-625

Area

EIA-625

S20.20

Notes

Static Generating Sources (Insulators)

£ ± 200 volts to be within 12"

³ 2K volts keep at a min. 12"

ESDA performed updated field studies

Auditing frequency

Tables 2 and 3 list item check frequency

6.1.3.1 Compliance Verification Plan Requirement recommends that the frequency of verification checks should be based on the control item usage, its durability and associated risk of failure

 

Humidity

RH at 40%

30% < RH < 70%

 

Auditing Body

Requires ESD Coordinator/team for compliance verification

Recommends use of external audits for verification compliance

 

Work Surface (General)

Recommends dissipative, not conductive

No statement (see notes)

20.20’s Forward, part C, recommends dissipative

Work Surface (specific)

³ 1.0x105 to < 1.0x109 ohms

< 1.0x109 ohms

(no lower limit)

No lower limit was set to allow stainless steel (cleanroom) worksurfaces to comply even though the worksuface’s committee disagrees

Floor (General)

Table 1 states - needed only when workers are mobile or workstations utilize floor grounding methods.

Section 6.2.2.2 states ESD protective flooring, used with approved footwear, may be used as an alternative to the wrist strap system for standing operations.

625 is a requirement, 20.20 is a recommendation

Floor (specific)

1.0x105 £ to < 1.0x109

< 1.0x109

Suggested lower limit in 625 is for safety

Footwear (General)

Wear two

No statement

 

Footwear (specific)

2.5x105 £ to £ 1.0x109 ohms for 120 volts

< 1.0x109 ohms

UL approves footwear with a minimum resistance of 1x106 ohms

Floor / Footwear System

Not covered

< 3.5x107 ohms or < 100 volts charge generation

First time a standard ties the floor and footwear together

Wrist Strap System

> 2.5x105 to < 1.0x107 ohms for 120 volts

< 3.5x107 ohms

UL approves wrist strap systems with a minimum resistance of 1x106 ohms

Smocks

£ ± 200 volts

105 £ to £ 1011 ohms

 

Ionizers

< ± 35 volts balance

< ± 50 volts offset voltage

Both reference ANSI EOS/ESD S3.1