Should you require our assistance in making measurements and advising you on your current or future ESD equipment, feel free to drop us an email sales@christensen.co.za. We have done this for many well know South African companies. We have ESD German trained staff that are equiped with the knowledge and skill to give you the correct findings and advice.
Here are some guidelines in conducting an Audit.
Conducting ESD Audits
1. The Importance of Audits
ESD audits are an essential part of a proper ESD control program. Audits check all ESD control
practices and products, identify problem areas and faculty equipment, provide a reminder to
personnel of their responsibilities and indicate are that require correct action.
The compliance of all aspects of the ESD equipment, procedures and training must be checked at
regular intervals, otherwise gradual deterioration can be expected. Equipment will fail over time and
materials and equipment will become non-compliant. Static awareness and correct use of
procedures will tend to gradually fade unless reinforced by refresher training.
An audit is based on an ESD control document that has been defined, approved by management,
and implemented at all operating levels. This document is usually based on a government, military or
industry standard for ESD.
In the audit, all facets of the ESD program must be checked to see that they are in accordance with
the ESD control document. Discrepancies must be recorded and reported to supervisors and to
company management as soon as possible.
Each company’s audit procedures are unique to the local control program or plan, but certain aspects
will be part of every program. The major areas to be examined are work area integrity, operator
conformance to proper procedures, condition of the workbench and floor, and general aspects of the
program.
2. Work Area Compliance
The audit must verify that the boundary that separates an ESD Protection Area (EPA) from non-EPA
areas is clearly defined. Signs, directional arrows, aisle marking tape, and other methods may be
used. This is a reminder to the workers in that area, of course, but also reminds visitors that they are
entering or exiting a sensitive control environment.
When entering an EPA, it should be easily identified by the use of signs, posters or other
designations to enforce the proper use of ESD controls.
Any supply carts in the sensitive area used to store or transport ESD sensitive devices should have
the uprights and shelves electrically connected and grounded to the ESD ground via a drag chain to
minimize tribocharging. A permanently attached ground snap to the cart is highly recommended for
hard grounding the cart when docked in an EPA.
Cleaning crews, contractor personnel, and maintenance workers must come into sensitive areas from
time to time. These visiting personnel should be quizzed or trained for ESD safe practices before
entering EPAs areas and instructed to not touch ESD-sensitive components.
Any visitor who will be in the area for an extended period should be required to wear a smock of a
different color from regular workers, or should be given a different-colored badge for control purposes. This makes it easy to identify and monitor them for ESD practices.
3. Employee Audit
Every operator, supervisor, material handler, or other employee that comes near sensitive equipment
or parts should go through an orientation to be certified or trained in ESD practices. A yearly
refresher ESD control training program is recommended for all personnel. Certification records
should be readily available to the auditor and to area supervisors.
There should be a self-check procedure in the area, and the auditor must verify that each operator is
aware of the procedure and follows it every day. Self-check shall ensure that the employee performs
the following:
Check the work area for charge generators
Wear and test personal grounding devices
Check for ESD insulators and remove them from the work area
Check that ESD sensitive equipment is in proper packaging with labels
Ensure that approved cleaners are on hand
Check that wiring of discharge devices is grounded
Ensure that ionizer is positioned and working properly
Ensure that non-grounded personnel stay a least a foot away from your static-safe area
Some companies require that every person entering the sensitive area pass a grounding test, and
that certification be verified. The audit must verify that such a system, if implemented, is operating
properly.
Each operator must wear the prescribed grounding devices at all times. A continuous monitor tests
the wrist strap and static mat connections continuously and sounds an alarm when there is a
problem. If an operator uses a monitor, the auditor must verify proper operation. If the monitor is not
used, the auditor must determine that wrist straps and heel straps are checked daily.
If smocks or other ESD outer clothing are required, the auditor must verify that that they are worn
properly and checked regularly. Smocks help to minimize problems with street clothing. Proper use
of a smock includes securing the smock at the opening and covering of the sleeves.
As an additional precaution, the smock may be grounded by connecting it to a grounded wrist strap or
ground cord at the hip connection. ESD garments should be bar-coded, laundered and tested
(sleeve-to-sleeve).
4. Work Benches and Floor Covering
The floors in an ESDP area must be checked for surface resistance, especially in the high-traffic
areas. A common high-end limit for this is 1 GW per ANSI/ESD-S7.1.
The auditor can check for high-end limit using a megohmeter that meets both ESD and ANSI/ESDstandards.
ANSI/ESD S20.20 states that footwear and flooring are individual elements. Each
element should be less than 1×10^9 ohms, but the total system resistance should be less than 35
Megohms. The best electrical check for a floor is surface resistance to ground (RTG) as this insures
a connection to ground as well.
Each workbench must be evaluated for ESD prevention, which involves removal of non-essential
insulators (such as coffee cups, radios, food wrappers, etc.) or the control of essential insulators via
ionization (such as some tools and jigs).
The workbench should have a dissipative-grounded work surface, a common point ground or
continuous monitor with banana jacks for grounding wrist straps and a ground cord to power ground
(connected to the common point ground or continuous monitor).
A good practice is to use a conformity sticker (always located in the same spot for each workstation)
indicating that the bench meets all ESD control requirements. If a sticker is missing, it denotes that
an infraction had occurred and not to use the bench. If the bench is ever moved then the sticker
should be removed until re-inspected.
The positioning of equipment that generates static must be monitored carefully in relation to ESDsensitive
equipment. The PC monitor, a well-known static generator, is necessary on many
production benches. The static generation from this device can be made acceptable by use of a wellgrounded
protective screen or a topical antistatic-dissipative treatment.
If ionizers are used on or above workbenches, then the audit must include a verification that each
ionizer is working properly. The checking procedure should be defined in the ESD document and the
audit should verify that each operator can and does follow that procedure.
Documents stored at the bench should be in dissipative holders and or binders. Packaging or
general purpose tapes found at the work bench should be verified that they are ESD safe (antistatic
and or dissipative) with a field meter.
5. Cleaning Materials and Packaging
The auditor must evaluate the types of cleaning materials and the cleaning practices for the work
area. Cleaners should not contain insulators such as silicon, soap, lanolin, free-salts, mineral oil, etc.
All sensitive components must be protected both as they arrive and as they leave the EPA. The
auditor must verify that proper care is taken. Equipment to be shipped is especially vulnerable,
because the manufacturer cannot control the environment in transit. Those goods must be packed
for the worst possible ESD environment.
6. Reporting Discrepancies
If there are any discrepancies, then the archived test records should be consulted to verify that the
control devices in question have been historically tested and comply to specifications. The
discrepancy must be recorded on the audit form as an infraction.
As each audit is completed, the auditor must go over it with the supervisor in charge of the area, and
must present it to plant management. Corrective recommendations will be a part of the report, and
the net result will be an improved or well-run ESD Control program.
7. ESD Test Schedule
An ESD coordinator, supervisor or other person responsible for the static control program should
regularly test all ESD control products to ensure that they are functioning properly.
The table below describes the test intervals recommended by the Electronics Industry Association, in
accordance with Standard ANSI/EIA-625.
ESD Test Schedule
Test Schedule ESD Control Item
Daily
Wrist straps, foot straps, footwear, smocks
Weekly
Workstations, floor mats, ESD ground connections
Monthly
Static surveys of EPA and work stations
Quarterly
RTG of flooring, ESD ground continuity
Semi-annually
Ionizer balance and charge decay
Annually
ESD system compliance to the ESD document
8. ESD Audit Checklists
MIL-HDBK-263 K has a suggested checklist to use in performing an ESD audit which encompasses
over 500 specific questions in several subjects:
Management
Training
Engineering
Procurement and shipping/receiving
Storage
Work areas
Intra- and inter-plant movement
ESDS protected work stations
Quality functions
The checklist should be tailored to reflect the requirements of the ESD control program as well as
complement the program plan.
9. ESD Standards
http://www.christensen.co.za/docs/esd-standards
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