If your company has an ESD Control Program per ANSI/ESD S20.20 in place, you need to define ESD protective packaging for ESD sensitive items (ESDs).
“The Organization shall prepare an ESD Control Program Plan that addresses each of the requirements of the Program. Those requirements include:
– Product Qualification
– Compliance Verification
– Grounding / Equipotential Bonding Systems
– Personnel Grounding
– ESD Protected Area (EPA) Requirements
– Packaging Systems
– Marking” [ANSI/ESD S20.20 clause 7.1 ESD Control Program Plan]
But where do you start? Don’t panic – we’re here to help and we’ll be following the guidelines set-out in the ESD Standard.
Definition and Purpose of ESD Protective Packaging
ESD Protective Packaging covers any materials coming into direct contact with ESD sensitive devices during handling, shipping and storage. You don’t need to worry about secondary or exterior packaging unless it’s used for ESD protection purposes.
“Packaging for ESD sensitive items is commonly derived by modifying existing packaging to prevent the packaging itself from causing static damage. The packaging generally retains physical and environmental protective qualities. ESD protective packaging has been modified further to prevent other sources of static electricity from damaging a packaged item.“ [ANSI/ESD S541 Foreword]
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 thus protecting your ESD sensitive devices inside.
“Transportation of electrostatic sensitive devices requires packaging that provides protection from electrostatic hazards in the transportation or storage system. In the case of an EPA designed with continuous grounding of all conductors and dissipative items (including personnel), packaging may not be necessary.” [ANSI/ESD S541 clause 6. Packaging Application Requirements]
Example of ESD Packaging
Packaging is to be determined for all material movements inside and outside of the ESD Protected Area (EPA). Best practice is to define the required packaging or material handling item on the product’s bill of materials. Remember: the ESD packaging is just 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 or in accordance with the contract, purchase order, drawing or other documentation necessary to meet customer requirements.” [ANSI/ESD S20.20 clause 8.4 Packaging]
Choosing your ESD Protective Packaging
Numerous factors need to be taken into consideration when choosing your ESD protective packaging including the “environment and device sensitivity.” [ANSI/ESD S541 Annex A.1 Environment and Device Sensitivity]
It is best recommended to follow these 6 steps:
- Understand the product sensitivity
You can gather information about the ESD sensitivity of an item by either measuring it in-house, contacting the manufacturer of the product or by analyzing published ESD sensitivity data.
- Determine the distribution environment for the packaged product
Knowing the environment in which the product is shipped and how it will be handled is extremely important. Humidity and temperature are the main factors to consider when it comes to choosing the right type of packaging for your ESD sensitive items. If items are susceptible to moisture, a barrier material should be chosen to prevent excessive humidity exposure. On the other hand, condensation may occur inside the packaging if temperatures vary around the dew point of the established interior conditions. In those instances, desiccant should be put inside of the package or the air should be removed from the package before shipment.
A Moisture Barrier Bag – click here for more information
- Determine the type of packaging system that is best suited for the intended application
The first step is to choose low charging or static dissipative materials when in contact with ESD sensitive devices. Many companies also require the packaging to protect the contents from a direct discharge or exposure to electric fields. In addition to these requirements, there are further questions that need to be asked:
- Returnable or reusable packaging?
- Disposable or one-time only packaging?
- Aesthetic requirements for packaging?
- Select and test packaging materials
Test methods are explained in ANSI/ESD S541 and will classify packaging materials as conductive, static dissipative or insulative.
- Design a packaging systemOnce the ESD sensitivity and distribution environment have been evaluated and available materials have been selected, the design of the packaging system can begin. Per the ANSI/ESD S541, the following general rules apply:
- Inside an EPA:
“Packaging used within an EPA (that satisfies the minimum requirements of ANSI/ESD S20.20) shall be:
- Low charge generation.
- Dissipative or conductive materials for intimate contact.Items sensitive to < 100 volts human body model may need additional protection depending on application and program plan requirements.”
[ANSI/ESD S541 clause 6.1 Inside an EPA]
- Outside an EPA:
“Transportation of sensitive products outside of an EPA shall require packaging that provides:
- Low charge generation.
- Dissipative or conductive materials for intimate contact.
- A structure that provides electrostatic discharge shielding.”
[ANSI/ESD S541 clause 6.2 Outside an EPA]
Example of ESD Packaging
In addition to these guidelines, there may be additional factors that should be considered, e.g.:
- Cost/value relationship: The cost of the packaging compared to the total value of the contents is important. Some companies choose less expensive packaging for less valuable parts.
- Handling: If rigorous handling is expected, cushioned packaging may need to be considered.
- Test the final packaging design for effectiveness
It is highly recommended to subject packages to the type of hazards that can be expected during shipments. These tests can, for example, involve the following:
- High voltage discharges to the exterior of the packaging
- Simulated over the road vibration
- Drop tests
- Environmental exposure
Final thoughts on ESD Protective Packaging
Now that you have an understanding of the factors to consider when choosing your ESD Protective Packaging, you’re ready to implement the above guidelines. ESD packaging comes in all sorts of shapes and forms so bear in mind to not just look at bags when deciding what type of packaging to choose.
Also, remember that ESD packaging should be marked. We’ll cover the specifics in a later post.