A company with an ANSI/ESD S20.20 ESD control program needs to document the program and define ESD protective packaging for ESD sensitive (ESDS) items. Packaging is to be defined for all material movement within the EPA and for outside the EPA. Best practice is to define the required packaging or material handling item on a product’s bill of materials. The ESD packaging is as important as a component part.
Customer contract packaging can take precedence, but otherwise “the organization shall define ESD protective packaging requirements, both inside and outside the EPA per ANSI/ESD S541.” [ANSI/ESD S20.20 section 8.4]
The ESD Association sells most of their documents. However, both ANSI/ESD S20.20 and ANSI/ESD S541 are available as complimentary downloads from www.ESDA.org.
The fundamentals of ESD control include grounding all conductors in the EPA. ESD packaging will have special material composition to lower the resistance so that when grounded, electrostatic charges will be removed to ground.
This is the Summary of ESD Protective Properties ANSI/ESD S541 Table 2:
|Low charging (antistatic)||Materials that have reduced amounts of charge accumulation as compared with standard packaging materials.|
|Dissipative or Conductive Resistance||Provides an electrical path for charge to dissipate from the package.|
|Discharge Shielding||Protects packaged items from the effects of static discharge that are external to the package.|
ANSI/ESD Table 3 lists Test Methods for Electrostatic Protective Packaging:
|Material Property||Test Method||Method Description||Limits|
|Low Charging (Antistatic)||ESD ADV11.2||Tribocharging of tubes, planar materials, bags, unit packs (vibration)||User defined|
|Conductive||ANSI/ESD STM11.11||Surface resistance of planar materials||< 104 ohms|
|ANSI/ESD STM11.12||Volume resistance of planar materials||< 104 ohms|
|Dissipative||ANSI/ESD STM11.11||Surface resistance of planar materials||> 104 to < 1011 ohms|
|ANSI/ESD STM11.12||Volume resistance of planar materials||> 104 to < 1011 ohms|
|ANSI/ESD STM11.13||Surface resistance 2-point electrode||> 104 to < 1011 ohms|
|Shielding||ANSI/ESD STM11.31||ESD Shielding of Bags||< 50 nanojoules|
Note that the unit of measurement for conductive and for dissipative is surface or volume resistance in ohms; not resistivity.
Statshield® bag film construction includes a metalized shielding layer. Shielding bags are designed to dissipate electrostatic charges over their surface, protecting ESDS contents from electrostatic fields and from ElectroStatic Discharge (ESD). Their surface resistance is dissipative, which is recommended when packaging in contact with the ESDS; per ANSI/ESD S541 section A.3 “Dissipative Material for Intimate Contact, to avoid rapid discharge to sensitive items, dissipative materials should be used as the layer of packaging that contacts the item.”
This is also true for enclosed Protektive Pak impregnated dissipative corrugated containers, either closed or with lid in place. The impregnated corrugated has a buried shielding layer that provides the shielding ESD control property so that ESD sensitive items can be stored or transported outside an ESD protected area.
Protektive Pak offers a number of ESD control packaging solutions, including Protektive Pak® Impregnated Dissipative Corrugated Products, Statshield Shielding Bags, Moisture Barrier Bags, Pink Poly Bags, and Labels for use within an ESD protected area (EPA) and for shipping outside an EPA. Protektive Pak products are designed to meet ANSI/ESD S20.20 and the ESD Association Packaging standard ANSI/ESD S541; they provide a great value balancing cost and durability.
ANSI/ESD S541 for the Protection of Electrostatic Discharge Susceptible Items Packaging Materials for ESD Sensitive Items
1. Define what you are trying to protect.
What is the Human-Body Model (HBM) withstand voltage of the most sensitive item? A prerequisite of ESD control is the accurate and consistent identification of ESD susceptible items. Some companies assume that all electronic components are ESD susceptible. However, others write their ESD control plan based on the device and item susceptibility or withstand voltage of the most sensitive components used in the facility. A general rule is treat any device or component that is received in ESD packaging as an ESD susceptible item.
2. Become familiar with the industry standards for ESD control.
A complimentary .pdf of ANSI/ESD S20.20-2014 can be downloaded from the ESD Association web site at www.ESDA.org. Also consider purchasing the ESDA’s ESD Handbook ESD TR20.20-2008.
3. Select a grounding / equipotential bonding system.
The 3rd-wire AC electrical equipment ground is the preferred, recommended ground reference.
4. Determine the method of ground for operators (Personnel Grounding).
The two options for grounding an operator are a wrist strap or foot grounders. Wrist straps must be worn if the operator is seated. If foot grounders are used, an ESD flooring system must be used. In some cases both wrist strap and foot grounders will be used. The 3rd-wire AC electrical equipment ground is the preferred, recommended ground reference.
5. Establish & Identify EPA(s) – ESD Protected Area(s).
ESD Control Plans must evolve to keep pace with costs, device sensitivities, and the way devices are manufactured. Define the departments and areas to be considered part of the ESD Protected Area. Consider if customers and/or subcontractors should be included. Implement access control devices, signs, and aisle marking tape to identify and control access to the ESD Protected Area(s).
6. Select ESD control items to be used in the EPA based on your manufacturing process.
7. Develop Packaging (Materials Handling & Storage) Plan.
When moving ESD susceptible devices outside an ESD protected area, it is necessary for the product to be packaged in an enclosed ESD Shielding Packaging.
8. Use proper markings for ESD susceptible items, system or packaging.
From ANSI/ESD S20.20-2014 section 8.5: “the Organization, in developing the ESD Control Program Plan, shall consider the need for marking.”
9. Implement a Compliance Verification Plan.
From ANSI/ESD S20.20-2014 section 7.4: “A Compliance Verification Plan shall be established to ensure the Organization’s fulfillment of the technical requ.rements of the ESD Control Program Plan”.
10. Develop Training Plan.
From ANSI/ESD S20.20-2014 section 7.2: “Initial and recurrent ESD awareness and prevention training shall be provided to all personnel who handle or otherwise come into contact with any ESDS items.”
11. Make the ESD Control Plan part of your internal quality system requirements.
A written ESD Control Plan provides the “rules and regulations”, the technical requirements for your ESD Control Program. This should be a controlled document, approved by upper management initially and over time when revisions are made. The written plan should include following:
- Qualified Products List (QPL) – A list of EPA ESD control items is used in the ESD control Plan
- Compliance Verification Plan- Includes periodic checking of EPA ESD control items, and calibration of test equipment per manufacturer and industry recommendations.
- Training Plan- An ESD Program is only as good as the use of the products by personnel. When personnel understand the concepts of ESD, the importance to the company of the ESD control program, and the proper use of ESD products, they will implement a better ESD control program improving quality, productivity, and reliability.
Lenovo Service posted a video on their youtube site called “Understanding Electrostatic Discharge (ESD) for Technicians.” We encourage you to take a look.
The video is very informative and does a good job of covering the basics of ESD control when working with ESD susceptible devices or components. The basic practices of controlling ESD when handling ESD susceptible items are pretty straight forward.
- Establish and control access to an ESD Protected Area. It can be one bench or a whole facility (or a field service kit that a Lenovo Service person might use)
- Ground all conductors including operators.
- Use a dissipative grounded surface for ESD susceptible products to be placed on if needed.
- Remove all non-process essential insulators from the ESD Protected Area. Use ionization to control charges on process essential insulators.
- If an ESD susceptible item needs to be removed from the ESD Protected Area, place it in a shielding bag or storage container that forms a faraday cage.
Application Photo of Surface Resistance Test Kit
A significant increase in the discipline of implementing the fundamentals of ESD control noted in ANSI/ESD S20.20 Foreword, calls for:
- Ground all conductors in the EPA including people
- Remove all insulators from the EPA or use ionizers for process necessary insulators
- Package ESD sensitive items going outside the EPA in packaging that provides electrostatic discharge shielding
We encourage developing a hatred for insulators. The alternatives are:
Remove the insulative item from the EPA
- Substitute the item with an ESD protective version (such as tape, document holders, material handling containers, plastic bottles, etc.)
- Periodically treat insulative surface with a topical antistat
- Neutralize electrostatic charges using ionization
Other ESD Control Items
Other EPA ESD control items to add to the ESD control program might include shelving, mobile equipment (carts), gloves, and/or seating.
Improve Compliance Verification Plan
- Consider greater frequency of internal audits per ESD TR53
- Use of computer data collection system for wrist straps and footwear testing, continuous monitors, and ionizers
- Use of ground continuous monitors for worksurfaces and other ESD elements
- Test ionizers more frequently, consider self monitoring ionizers, consider computer based data collection
- Increased testing using static field meter to verify that automated processes (like auto insertion, tape and reel, etc) are not generating charges above acceptable limits.
Application Photo of Volt Meter and Software in Factory STM97.2 Testing Voltage Charge on Person (Photograph courtesy of TREK, INC.)
- ESD awareness training for all in the EPA or who may come into the EPA including suppliers
- Testing to verify comprehension and training adequacy
- Training on the proper use of test equipment
- Training on proper compliance verification test procedures
Application Photo CD-ROM ESD Training
Just to maintain a company’s current level of quality and reliability may require a substantial improvement in a company’s ESD control program. Now is the time for improvement as ESD sensitivity withstand voltages continue to get lower and companies may soon be handling class 0A HBM items. To combat HBM failures improved personnel grounding is required. For example, heel grounders should be replaced with full coverage foot grounders. However, most failures are CDM. To combat CDM failures, ionization should be added or improved, and conductive surfaces should be covered with dissipative material. In general, disciple should be enhanced implementing ESD control fundamentals, compliance verification testing should be increased, and training should be improved.
From published article “Now is the Time for ESD Control Programs to be Improved” by Fred Tenzer and Gene Felder. See full article at InCompliance Magazine- September 2012
- ESD protective product to replace high charging plastic trash cans
- Chemical and moisture resistant
- Superior strength and durability; made from extruded
high impact polypropylene material
- Convenient fold down design for easy storing
- Conductive Rtt 1 x 10E2 < 1 x 10E5 ohms
- ESD protective liners also available
- Made in the United States of America
Economy Pink Liners:
- Ideal for use inside ESD protected areas
- Low cost, economical
- Surface Resistance: < 10E11 ohms
- Durable Thickness: 0.002 in (2.0 mil)
- Packaged 50 bags per pack
- Made in the United States of America
|37816||Trash Receptacle, 12-1/2” x 10” x 14”, 10 Gal.||$35.93||$34.85||$33.81||$32.12|
|37817||Trash Receptacle, 21” x 12-3/4” x 28”, 36 Gal.||$54.29||$52.66||$51.08||$48.53|
|37822||Economy Pink Liner, 26” x 26”, 10 Gal.||$25.90||$24.61||$22.70||$22.01|
|37823||Economy Pink Liner, 36” x 40”, 36 Gal.||$62.10||$60.24||$58.43||$56.68|
“It should be understood that any object, item, material or person could be a source of static electricity in the work environment.
The removal of unnecessary nonconductors, replacing nonconductive materials with dissipative or conductive materials and
grounding all conductors are the principle methods of controlling static electricity in the workplace, regardless of the activity.”
*The prices in the Protektive Pak Online Catalog supersede all pricing on new product announcements and may change without notice.
Do Protektive Pak In-Plant Handlers need to have lids on while ESD sensitive items are in them? How do these Protektive Pak In-Plant Handlers work?
Outside the ESD protected area (EPA), the Protektive Pak lids need to be in place to provide the electrostatic discharge shielding ESD control property which is required by the Packaging standard ANSI/ESD S541. Per section 6.2 Outside an EPA “Transportation of sensitive products outside of an EPA shall require packaging that provides: 1. Low charge generation. 2. Dissipative or conductive materials for intimate contact. 3. A structure that provides electrostatic discharge shielding.”
Inside the EPA, it would still be a good idea to have the lid in place, but it is not a requirement. The Protektive Pak impregnated corrugated has a buried shielding layer. In shielding, we utilize the fact that electrostatic charges and discharges take the path of least resistance. The charge will be either positive or negative; otherwise the charge would balance out and be no charge.
Like charges repel and so the electrostatic charge will reside on the outer conductive surface.
A Faraday Cage effect can protect ESDS contents in a container with a shielding layer (this is what a shielding bag has). This Faraday Cage effect protects people in real life when a lightning bolt strikes an airplane or automobile with the charge residing on the outer metal fuselage or car body.
The Faraday cage effect causes charges to be conducted around the outside the surface of the conductor. Since like charges repel, charges will rest on the exterior.
To complete the enclosure, make sure to place lids on boxes or containers, and close shielding bags. Packaging with holes, tears, or gaps should not be used as the contents may be able to extend outside the enclosure and lose their shielding as well as mechanical protection.
To ask an ESD question Click Here
To view In-Plant Handlers Click Here
Gene Felder of Desco Industries describes the ANSI/ESD Standard S20.20 and how it applies to an ESD control program.
To see Protektive Pak’s video channel Click Here.
|39170||ESD Area Sign||
|39170||ESD Area Sign||
Promo Code: PromoP354
September 29, 2011