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
Protektive Pak’s Dissipative Impregnated Corrugated material features a unique characteristic, a buried shielding layer. This provides a better value because unlike dissipative or conductive painted material, the buried shielding layer will not rub/scratch off or lose its ESD properties. This translates into a superior, longer lasting ESD safe package.
Third party testing has been performed on Protektive Pak’s Impregnated Corrugated material demonstrating that the buried shielding layer in our corrugated material provides a better value than dissipative or conductive coated (or painted) material.
- Protektive Pak impregnated corrugated material has a buried shielding layer
- Protektive Pak impregnated corrugated material equals or exceeds the discharge shielding capabilities of a coated box
- Protektive Pak impregnated corrugated material has discharge shielding capabilities equal to a metal-out shielding bag
- Protektive Pak Dissipative Corrugated Material meets the ANSI/ESD S541 recommendation, avoiding rapid discharge when contacting ESD sensitive items –
conductive coated boxes DO NOT!
Protektive Pak Dissipative Impregnated Corrugated Material meets ANSI/ESD S20.20 and Packaging standard ANSI/ESD S541 tested per ANSI/ESD STM11.11 and modified ANSI/ESD STM11.31
For complete third party test results, click HERE.
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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.
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“Returnable Packaging,” as defined by Returnable Packaging Association (RPA), is packaging which includes “…reusable pallets, racks, bulk containers, hand-held containers and dunnage that move product efficiently and safely throughout the supply chain. Reusable packaging is typically used by manufacturers/processors and their suppliers/customers in a well-organized supply chain, with very tightly managed shipping loops.”
So what does this mean? Returnable packaging is manufactured of durable materials and is specifically designed for multiple trips and extended life.
When a vehicle leaves a facility to drop off product and then returns to pick up more product, you have what is called a “milk run”. Milk runs are perfect for returnable packaging.
Utilizing returnable packaging cuts down on material costs as well as total cost. There is much less need for repeated purchasing of disposable containers. The money saved will now go towards your profit line! In addition, returnable packaging cuts down on waste by re-using packaging rather than just using it once and throwing it away. No more dumpsters full of unneeded waste!
Protektive Pak In-Plant Handlers are a great choice for reusable packaging. Made to protect ESD sensitive components, the boxes are constructed with double thick sides and double or triple thick ends and are extremely durable. They withstand the abuse of transporting. After transporting product to another facility, the boxes can be reused to ship more product or collapsed and stored for future use.
ElectroStatic Discharge (ESD) is silent, quick and potentially lethal to electronic parts. When electronic parts are not properly handled during manufacturing, assembly, storage, or shipping, damage from ESD can reach into the millions of dollars each year.
For an ESD control container to be effective against ElectroStatic Discharge, it must possess certain electrical characteristics:
- Surface resistance <1 x 1011 ohms per ANSI/ESD STM11.11
- Energy penetration <50 nanoJoules per ANSI/ESD STM11.31
Non-shielding containers might be cheaper, but they are not less costly when it comes to handling ESD sensitive items. Anytime ESD sensitive parts and assemblies are handled, regular containers are not a sound option, even part of the time, as the risk of ESD damage is always lingering. As a result, costs will be incurred, either via ESD damage or as an additional investment in discharge shielding packaging and material handling containers.
The disadvantages of cross-using shielding and non-shielding containers include:
- Increased cost
- Risk from ESD damage
- Handling inconvenience
The cost of a discharge shielding container is far less than the cost associated with damaged parts or extra handling that result with a “less expensive” non-shielding container.
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
Gene Felder of Desco Industries describes the ANSI/ESD Standard S20.20 and how it applies to an ESD control program.
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Rely on Protektive Pak® for ESD Packaging Solutions
Protektive Pak is a leading manufacturer of ESD Material Handling and Packaging solutions. We offer a complete line of ESD Packaging products for transporting, storing and shipping of static sensitive assemblies. Our products include Storage Containers, Circuit Board Shippers, Open Bin boxes, Reel Storage Containers, Trays, Foam, Tape, Shielding Bags and much more! We also have custom manufacturing capabilities to your meet your special needs, including Thermoforming requirements.
Protektive Pak offers a unique “Impregnated” corrugated material that provides greater durability than “painted” corrugated material. The buried shielding layer protects ESD sensitive items (ESDS) and minimizes sloughing and rub-off contamination. We also offer Plastek Industrial Fluted Plastic, an economical alternative to injection molded products and ideal for use where corrugated and /or paper products cannot be used.
For further information, please visit our website at www.ProtektivePak.com