ANSI ESD-S20.20-2021-EN.pdf - 第26页

ANSI/ESD S20.20- 2021 18 (This annex is no t part of ESD Association Standard ANSI/ESD S20.20- 2021 ) ANNEX E (INFORMATI VE) – STAT EMENT OF DI RECTION These sections may be included in future r evisions of ANSI/ESD S20.…

ANSI/ESD S20.20-2021

ANSI/ESD SP17.1, ESD Standard Practice for the Protection of Electrostatic Discharge

Susceptible Items – Process Assessment Techniques

ESD TR20.20, ESD Association Technical Report – Handbook for the Development of an

Electrostatic Discharge Control Program for the Protection of Electronic Parts, Assemblies, and

Equipment

JESD625, Requirements for Handling Electrostatic-Discharge-Sensitive (ESDS) Devices

IPC/JEDEC J-STD-033, Handling, Packing, Shipping and Use of Moisture Reflow, and Process

Sensitive Devices

TR3.0-02-05, Selection and Acceptance of Air Ionizers

ESDSIL, Reliability Analysis Center (RAC) ESD Sensitive Items List

JESD471, Symbol and Label for Electrostatic Sensitive Devices

IEC 61340-5-1, Protection of Electronic Devices from Electrostatic Phenomena – General

Requirements

VZAP, Electrostatic Discharge Susceptibility Data

ISO 9001, Quality Management Systems – Requirements

ANSI/ESD S20.20-2021

(This annex is not part of ESD Association Standard ANSI/ESD S20.20-2021)

ANNEX E (INFORMATIVE) – STATEMENT OF DIRECTION

These sections may be included in future revisions of ANSI/ESD S20.20. The sections are placed

here for information only and do not have to be implemented.

E.1 Component Threshold Plan

It is important to know what the human body model and charged device model classifications are

for any ESDS item that will come into the process. A plan should be established to determine,

before initial use, that ESDS item thresholds are within the scope of this standard.

The recommended test methods for establishing the HBM and CDM levels are ANSI/ESDA/JEDEC

JS-001 and ANSI/ESDA/JEDEC JS-002, respectively. Ideally, HBM and CDM thresholds would be

available and reported in component datasheets. For example, ANSI/ESD SP5.0 contains a

template for reporting ESD data.

NOTE: The following would be acceptable objective evidence by including the following question in

contractual agreements: "Are any components in this contract outside the scope of ANSI/ESD S20.20

(< 100 volts HBM; < 200 volts CDM)?". Alternatively, a similar question could be included in manufacturing

readiness reviews, design reviews, component datasheet reviews, or any other documented process for

obtaining component information

E.2 Process Assessments

The current version of the standard does not require any data to support claims of handling devices

with 100 volts HBM and 200 volts CDM sensitivities. In a future release of this standard, it is the

goal to require data to support the HBM and CDM claims. There currently are no standards or

standard test methods that can provide data to support the claims. A working group within the ESD

Association is working to provide test methods to "measure" the process. When these test methods

become available, there may be a requirement added to future revisions of this standard to provide

data related to the process capability of the installed ESD process.

Measurements may include, but are not limited to:

• The voltage on devices in the process

• The voltage on printed circuit boards while moving through the process

• Discharge current measurements

For more information, please see ANSI/ESD SP17.1, ESD Standard Practice for the Protection of

Electrostatic Discharge Susceptible Items - Process Assessment Techniques.

ANSI/ESD S20.20-2021

(This annex is not part of ESD Association Standard ANSI/ESD S20.20-2021)

ANNEX F (INFORMATIVE) – REVISION HISTORY FOR ANSI/ESD S20.20

F.1 2014 Version

Foreword: Added CDM and MM sensitivities to the foreword and a section on Facility Certification.

2.0 Scope: Added 200 volts CDM and 35 volts on isolated charged conductors that this standard

applies.

6.1 ESD Control Program Requirements: Second sentence was revised to "The Program shall

document the lowest level(s) of device ESD sensitivity that can be handled" from "The most

sensitive level of the items to be handled, per the Program, shall be documented."

7.1 ESD Control Program Plan: Product Qualification was added as a required element.

7.3 Product Qualification: Section was added.

7.4 Compliance Verification Plan: Renumbered from 7.3, the content remained the same.

8.2 Personnel Grounding: Note was removed, and the text was made a requirement for garments.

Standing requirements were changed; Method 1 and Method 2 have been changed to one method

of qualification for standing.

8.3 ESD Protected Areas (EPAs): Additional requirement for process essential insulators was

added. Within 1 inch of the ESDS items, the limit for fields was reduced to 125 volts/inch.

Table 3: Wrist Strap Cord Bending Life was removed. Ionization offset voltages were updated for

room systems. Soldering iron requirements were added.

8.4 Packaging: The section was reworded, but the requirements remained the same.

Annex A: Soldering Irons were moved into Table 3. Conveyor systems were added to this section.

Annex B: Updated HBM standard to ANSI/ESDA/JEDEC JS-001 in Table 4.

F.2 Revisions to 2014 Version

F.2.1 December 15, 2021 Version

General changes to improve clarity.

3.0 References: Added reference to MIL-STD-2073-1

4.0 Definitions: Definitions for ESD control items, insulator, conductor, isolated conductor, and

unprotected ESDS item were added and only apply to this document.

6.3 Tailoring: Updated wording for tailoring for clarity. A reference to a new annex with examples

was added.

7.3 Product Qualification: Several changes were made to the requirements. Qualification for ESD

control items that stay on-site can be done at the lowest RH on the site. This does not apply across

multiple sites or materials that leave the site. Qualification records are now required to include

supporting technical reports. Added explanation that the flooring/footwear system cannot use

compliance verification data for qualification. Body voltage measurements must also be made.

7.4 Compliance Verification Plan: Note added that calibration does not imply the equipment can

make measurements.

8.1 Grounding/Equipotential Bonding Systems: A statement that compliance verification of the

grounding system is not required was added. No change in the requirements.

8.3.1 Insulators: The section was updated with a field measurement of where the ESDS item is

handled. The original measurement was retained, and either could be used.

8.3.2 Isolated Conductors: The inclusion of non-contact electrostatic voltmeters and electrostatic

field meters were included with a note on measurement issues.

Table 3: Deleted ANSI/ESD STM4.2 as a qualification for worksurfaces. Added point-to-point

requirements to groundable static control garments and groundable static control garment systems.