ESD Packaging and Transport

ElectroStatic Discharge (ESD) can pose danger to a Printed Circuit Board (PCB). A standard bare PCB (meaning that it has no semiconductor components installed) should not be susceptible to ESD damage, however as soon as you add electronic (semiconductor) devices, it becomes susceptible according to each of the individual’s susceptibility.

While ESD damage can post a danger, there is another risk factor many operators forget: moisture.

Today’s blog post is going to address both risks and will explain how you can protect your PCBs from both when storing them.

The problem with moisture

If you have been following along with our blogs, you will be well aware of the problems ESD damage can cause.

Moisture, on the other hand, may be a new issue to you. Surface Mounted Devices (SMDs), for example, absorb moisture and then during solder re-flow operations, the rapid rise in temperature causes the moisture to expand and the delaminating of internal package interfaces, also known as “pop corning.” The result is either a circuit board assembly that will fail testing or can prematurely fail in the field.

Moisture.png
Moisture from air diffuses inside the plastic body & collects in spaces between body & circuit, lead frame and wires. Expanding vapor can crack (popcorn) the plastic body or cause delamination.

Storing PCBs

All PCBs should be stored in a moisture barrier bag (MBB) that is vacuum sealed. In addition to the bags, Desiccant Packs and Humidity Indicator Cards must be used for proper moisture protection. This ‘package’ is also known as a dry package.

Most manufacturers of the Moisture Sensitive Devices (MSD) will dictate how their product should be stored, shipped, etc. However, the IPC/JEDEC J-STD-033B standard describes the standardized levels of floor life exposure for moisture/reflow-sensitive SMD packages along with the handling, packing and shipping requirements necessary to avoid moisture/reflow-related failures.

The ESD Handbook ESD TR20.20 mentions the importance of moisture barrier bags in section 5.4.3.2.2 Temperature: “While only specialized materials and structures can control the interior temperature of a package, it is important to take possible temperature exposure into account when shipping electronic parts. It is particularly important to consider what happens to the interior of a package if the environment has high humidity. If the temperature varies across the dew point of the established interior environment of the package, condensation may occur. The interior of a package should either contain desiccant or the air should be evacuated from the package during the sealing process. The package itself should have a low WVTR.

Components of a dry package

A dry package has four parts:

  1. Moisture Barrier Bag (MBB)
  2. Desiccant
  3. Humidity Indicator Card (HIC)
  4. Moisture Sensitive Label (MSL)

 

 3371014.jpg Moisture Barrier Bags (MBB) work by enclosing a device with a metal or plastic shield that keep moisture vapor from getting inside the bag. They have specialized layers of film that control the Moisture Vapor Transfer Rate (MVTR). The bag also provides static shielding protection.
Desiccant is a drying agent which is packaged inside a porous pouch so that the moisture can get through the pouch and be absorb by the desiccant. Desiccant absorbs moisture vapor (humidity) from the air left inside the barrier bag after it has been sealed. Moisture that penetrates the bag will also be absorbed. Desiccant remains dry to the touch even when it is fully saturated with moisture vapor.

The recommended amount of desiccant  depends on the interior surface area of the bag to be used. Use this desiccant calculator to determine the minimum amounts of desiccant to be used with Moisture Barrier Bags.

1-6PLDES1200.jpg
3HIC125.jpg Humidity Indicator Cards (HICs) are printed with moisture sensitive spots which respond to various levels of humidity with a visible color change from blue to pink. The humidity inside barrier bags can be monitored by the HIC inside. Examining the card when you open the bag will indicate the humidity level the components are experiencing so the user can determine if baking the devices is required.
The Moisture Sensitive Level (MSL) label tells you how long the devices can stay outside the bag before they should be soldered onto the board. This label is applied to the outside of the bag. If the “level” box is blank, look on the barcode label nearby. 113LABEL.jpg

5 Steps to Create a Dry Package

Now that we know the risks moisture poses to ESD components, follow these 5 steps to create a secure, dry package which will protect your PCBs against ElectroStatic Discharge and moisture:

  1. Place the desiccant and HIC onto the tray stack. Trays carry the devices. Remember to store desiccant in an air tight container until it used.
    Dry-Packaging-Step1.png
  1. Place the MSL label on the bag and note the proper level on the label.
    Dry-Packaging-Step2.png
  2. Place the tray stack (with desiccant and HIC) into the moisture barrier bag.
    Dry-Packaging-Step3.png
  3. Using a vacuum sealer, remove some of the air from the bag, and heat seal the bag closed. It is not good to take all the air out of the bag. Only slight evaluation is needed to allow the bag to fit inside a box.
    Dry-Packaging-Step4.png
  4. Now your devices are safe from moisture and static.
    Dry-Packaging-Step5.png

With the steps taken above, your package should now be properly sealed from moisture and protected from ElectroStatic discharge.

Looking for a moisture barrier bag for your application? See the SCS Moisture Barrier Bag Selection Guide to find the packaging that fits your specifications!

Are your static and moisture sensitive components protected by your packaging? Learn how to minimize potential product failures by protecting your products from Electrostatic Discharge (ESD) and moisture during the manufacture, transportation, and storage process.

Why are Moisture Barrier Bags important?

Moisture Barrier Bags (MBB) shield ESD sensitive devices from 2 potential risks:

  1. The Faraday Cage created when using these bags protects contents from ESD Damage.
  2. Specialized layers of film controlling the Moisture Vapor Transfer Rate (MVTR) also protect contents from moisture.
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Moisture Barrier Bags – more information

“Desiccant” and “humidity indicator cards” must be used for proper moisture protection.

But what exactly are “desiccant” and “humidity indicator cards” and how are they used? These are the questions we will clarify in today’s blog post.

What is desiccant?

Desiccant is a drying agent that absorbs moisture from its surrounding area. Desiccant will stay dry to the touch even when it is fully saturated with moisture.

In a Moisture Barrier Bag it is used to ‘soak up’ moisture from the air inside the bag AFTER it has been sealed. Any moisture that gets through the bag from the outside will also be absorbed.

How is desiccant purchased?

Desiccant is available as a “unit” or fractional “unit”. A unit of desiccant absorbs a specific amount of moisture. One unit of desiccant weighs about 28g.

How is desiccant packaged?

Desiccant is packed in small sealed pouches made from a white plastic called “Tyvek” or brown “Kraft” paper. Tyvek pouches are very clean and Sulphur free. Kraft pouches are economical.

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A desiccant pouch – more information

Pouches of desiccant are placed into metal pails – this ensures the desiccant is kept dry during transport and storage.

How much desiccant do you need?

There are 2 different methods you can use:

  1. Method 1 per MIL-P-116
    Formula: Unit = 0.011 x bag area in square inches
    What you need: Bag area (2 times the surface area of your bag as there are 2 sides to a bag)
    Example: 10” x 20” MBB bag
    Apply formula: 0.011 x (10” x 20” x 2) = 4.4 rounded up to 4.5 units of desiccant
  2. Method 2 per EIA 583 (allows you to tailor desiccant to your specific needs)
    Formula: Unit = 0.231 x Bag Area x Bag MVTR x Months divided by Moisture Capacity
    What you need: Bag area, Bag MVTR, Months of Storage, Maximum Interior Humidity (MIH), Moisture capacity table below:
10% MIH 3.0 g/unit
20% MIH 4.8 g/unit
30% MIH 5.8 g/unit
40% MIH 6.2 g/unit

Example: 10” x 20” bag with a 0.02 MVTR, a 12 month storage time and a MIH of 20%
Apply formula: 0.231 x (10″ x 20″ x 2) x (0.02) x (12/4.8) = 4.62 rounded down to 4.5 units of desiccant

What is a humidity indicator card?

A humidity indicator card allows for quick visual inspection of the relative humidity levels within its surrounding area. They are printed with moisture sensitive spots which respond to various levels of humidity with a visible color change from blue to pink.

In a Moisture Barrier Bag they provide a low-cost method of verifying the effectiveness of the moisture barrier packaging. If you are using Moisture Barrier Bags, moisture will be an issue in your application so you’re obviously aiming for as little moisture as possible. However, if you happen to open your MBB and the humidity indicator card shows a relative humidity of 60%, you’ll know that the contents of your bag have been exposed to moisture and may not be safe for use anymore.

How are humidity indicator cards purchased?

Humidity indicator cards come in many shapes and forms. Some will show relative humidity from 10% – 60%; others from 5% to 15%. Depending on the sensitivity of your application to moisture, the correct type of card should be chosen.

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A humidity indicator card – more information

Bear in mind that not all humidity indicator cards are reversible. Some cards will measure the relative humidity only once and then halt at that reading. These types of humidity indicator cards are NOT re-usable. This is important to know so make sure you check before purchasing!

How are humidity indicator cards packaged?

Humidity indicator cards are sold in containers. It is recommended that cards are stored in their original un-opened canister in a dry, well ventilated room with a reasonably consistent temperature of 20°C. Humidity indicator cards should not be stored in ultraviolet sunlight, moisture or heat.

How many humidity indicator cards do you need?

One humidity indicator card per MBB is needed for proper verification of relative humidity.

Conclusion

Moisture Barrier Bags, desiccant and humidity indicator cards all play a very unique and important role when protecting ESD sensitive devices from moisture.

Moisture-Barrier-bag-w-HIC.jpg
Protect your static and moisture sensitive components with proper packaging

They should always be used together to ensure maximum protection. However, remember that all three tools need to be used correctly as otherwise all your efforts have been in vain. And don’t forget: your Moisture Barrier Bag must be heat sealed with a vacuum sealer to eliminate the amount of “moisture laden air” within the package.

Find the right protective packaging for your sensitive components! Check out the SCS Moisture Barrier Bag Selection Guide and Humidity Indicator Card and Desiccant Chart to find the right packaging products for your application.

In a previous post we learnt how to select the correct ESD bag for your application, we want to focus on the next step: how to correctly use your ESD bag. We’ll use shielding bags as an example as they are the most commonly used ESD bags. However, the below can be applied to all types of ESD bags.

There are a few “dos and do-nots” you should keep in mind to ensure you get the most from your ESD bags. Nothing is worse than investing in all the right equipment and then using it incorrectly rendering all your efforts void. So, on that note, we have comprised a list of 5 tips for you on how to most efficiently use your shielding bags.

5 Tips On Efficient Use of Shielding Bags With ESD Sensitive Items:

1. Enclose Your ESD Sensitive Item with a Shielding Bag

Shielding bags should be large enough to enclose the entire product within. The shielding bag should be closed with a label or tape. Alternatively, you can use a zipper-style shielding bag. Following this advice ensures a continuous Faraday Cage is created which provides electrostatic shielding. This is the only way to ensure ESD sensitive devices placed inside the shielding bag are protected. If you are unfamiliar with the term “Faraday Cage”, scroll to the bottom of this page – we’ve included a more detailed explanation at the end of the post.

 

Enclose_Shielding_Bags
Enclose your ESD sensitive item

 

Please do not staple your shielding bag. The staple punctures the shielding layers and will provide a conductive path from the outside of the shielding bag to the inside. Charges outside the shielding bag could potentially charge or discharge to ESD sensitive components inside the shielding bag.

If you’re unsure as to what the correct size is for your application, catch-up on this post which will provide all the required information.

2. Remove Charges from Shielding Bags

When receiving an ESD sensitive device enclosed in a shielding bag, make sure you place the closed shielding bag on an ESD worksurface before removing the product. This will eliminate any charge that might have accumulated on the surface of the shielding bag.

 

Remove_Static_Charges.jpg
Remove charges

 

 3. Do Not Overuse Shielding Bags

Re-using shielding bags is acceptable as long as there is no damage to the shielding layer. Shielding bags with holes, tears or excessive wrinkles should be discarded.

 

Dont_overuse_shielding_bags
Don’t overuse shielding bags


 4. Shielding Bags Are Not A Working Surface

Do not use a shielding bag as an ESD worksurface. Although a shielding bag is safe to use around ESD susceptible products, it is not intended to be a worksurface for product. When working on ESD sensitive devices, do so using ESD worksurfaces that are grounded correctly.

Shielding_Bags_are_no_ESD-Worksurface.jpg
Don’t use shielding bags as your ESD worksurface

 5. A Shielding Bag Is Not A “Potholder” Or “Glove”

Do not use a shielding bag as an “ESD potholder” or “ESD glove”. This type of use offers no ESD protection to the product.

If you need to handle ESD sensitive devices, make sure you are properly grounded using wrist straps or heel grounders.

Shielding_Bags_are_no-Gloves
Shielding bags are no “ESD glove” or “ESD potholder”

Some of you may have read through this post and have stumbled across the term “Faraday Cage” as you have not come across it before. We’ve also mentioned it before when talking about storing and transporting ESD sensitive items. However, we’ve never actually explained what a Faraday Cage is – so let’s rectify that!

What Is A “Faraday Cage” Or “Faraday Shield”?

A Faraday Cage or Faraday shield is an enclosure formed by conducting material or by a mesh of conductive material. Such an enclosure blocks external static and non-static electric fields. Faraday Cages are named after the English scientist Michael Faraday, who invented them in 1836.

What Is An Example of Faraday Cage Effect?

An impressive demonstration of the Faraday Cage effect is that of an aircraft being struck by lightning. This happens frequently but does not harm the plane or passengers. The metal body of the aircraft protects the interior. For the same reason, a car may be a safe place during a thunderstorm.

 

Lightning.jpg
Lightning striking an airplane

 

How Is A Faraday Cage Effect Used In ESD Protection?

In ESD Protection, the Faraday Cage effect causes charges to be conducted around the outside surface of the conductor. Since similar charges repel, charges will rest on the exterior and ESD sensitive items on the inside will be ‘safe’.

Examples of ESD control products that provide a Faraday Cage or shielding include Metal-In and Metal-Out Shielding bags.

When Is ESD Shielding Packaging Used?

ESD shielding packaging is to be used particularly when transporting or storing ESD sensitive items outside an ESD Protected Area.

ESD Packaging Standards For Outside An EPA

Per Packaging Standard ANSI/ESD S541 clause 6.2 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.

Additional ESD Definitions

Other helpful ESD related definitions from the ESD Association Glossary ESD ADV1.0 include:

Faraday Cage“A conductive enclosure that attenuates a stationary electrostatic field.
Electrostatic discharge (ESD) shield: “A barrier or enclosure that limits the passage of current and attenuates an electromagnetic field resulting from an electrostatic discharge.
Electrostatic shield: “A barrier or enclosure that limits the penetration of an electrostatic field.

So, hopefully we’ve clarified a few things today when it comes to the “shielding” property by explaining the phenomenon of the “Faraday Cage”. Don’t forget to implement our tips when it comes to using your ESD bags!

 

Last time, we discussed the storage requirements of ESD sensitive items. Today we want to focus on the overall selection process for ESD bags: from choosing the correct type of material all the way through to determining the right size for your application. Sounds complicated? Honestly – it’s not and once you have the right tools (you’re welcome!), you’ll be an expert in no time. So, let’s go!

Choose the correct material for your ESD bag
Before you get started, you need to be clear about the purpose of your ESD bag and the environment it’s being used in. Make sure you have the answers to the following questions:

  1. What do you intend to put inside the ESD bag? ESD sensitive items? Non-ESD sensitive items?
  2. Is moisture an issue you need to consider?
  3. Do you need your ESD bags to be self-sealable? Or will you be using ESD tape/labels to close your bags?
  4. Are the items inside your ESD bag sensitive to physical damage?
  5. Are the items you’re storing in your ESD bag particularly sharp which could potentially damage the material?
  6. Will the ESD bags (and obviously the items inside) be stored on a grounded shelf inside an EPA or are they being transported outside of an EPA, as well?

Once you have answers to ALL of the above questions, you can move on to the below selection chart and choose the right material for your application.

ESD sensitive items Moisture protection Self-sealable Physical protection Inside/
Outside EPA
Metal-In x x Both
Metal-Out x x Both
MBB – High Barrier x x x Both
MBB – Low Barrier x x x Both
Bubble Shielding x x Both
Conductive Black Only if used on a grounded surface Inside only if used with ESD sensitive items

A few more details on the different types of materials listed in the above chart:

  1. Metal-In Shielding Bags
    ESD bags which protect ESD sensitive items. The ESD shielding limits energy penetration from electrostatic charges and discharge. The dissipative outer layer dampens any discharge and therefore reduces damaging electrostatic events. They offer good see-through clarity. Available with and without dissipative zipper.

    Metal-In Shielding Bag – more information
  2. Metal-Out Shielding Bags
    Integral antistatic and low tribocharging bags which will not electrostatically charge contents during movement. Bags have a protective coated aluminum metal outer layer of laminated film; this promotes a more rapid discharge of static fields creating the event which the metal layer then attenuates. If RF field sensitivity is an issue, metal-out bags may be unsuitable. The rapid discharge to the highly conductive outer layer can create a higher radiated field which in return can cause issues for objects inside or near the bag. Available with and without dissipative zipper.

    Metal-Out Shielding Bag – more information
  3. Moisture Barrier Bags (MBB) – Low Barrier
    Offers ESD and moisture protection and can be used to pack SMD reels or trays. Available with and without dissipative zipper (except Dri-Shield® 2700).

    Low Barrier Moisture Barrier (MBB) Bag – more information
  4. Moisture Barrier Bags (MBB) – High Barrier
    Offer ESD and moisture protection and are ideal for applications where high moisture protection or conformance to IPC/JEDEC J-STD-033 is required. Available with and without dissipative zipper (except Dri-Shield® 3000).

    High Barrier Moisture Barrier (MBB) Bag – more information
  5. Cushioned Bags
    These bags combine the “Faraday Cage” and mechanical protection. They shield about twice as well as normal shielding bags of equivalent size. Bubble cushion layer provides heavy-duty protection that absorbs impact and prevents product damage.

    Cushioned Bag – more information
  6. Conductive Black Bags
    Black conductive film is made of virgin low density materials with black conductive compound to achieve high toughness and strength. This is commonly used for material handling, shipping and storage.

    Conductive Black Bag – more information

Calculating the correct size for your ESD bag
Once you have selected the correct type of material, it’s time to choose the right size for your ESD bag. There are different ways to determine this based on the type of material you use:

Shielding and Black Conductive Bags:
A. Bag Width = Item’s Thickness + Item’s Width + 25mm
B. Bag Length = Item’s Thickness + Item’s Length + 50mm

Moisture Barrier Bags (MBB):
A. Bag Width = Item’s Thickness + Item’s Width + 25mm
B. Bag Length = Item’s Thickness + Item’s Length + 76mm

Cushioned Bags:
A. Bag Width = Item’s Thickness + Item’s Width + 76mm
B. Bag Length = Item’s Thickness + Item’s Length + 76mm

Bonus Tip: Measuring a bag
It might seem obvious to some of you but given that we do get these types of queries on a regular basis, we thought this would be a good opportunity to include. Imagine you already have ESD bags that you use in your company. Someone has just taken the last one off the shelf and you need to order some more. How do you know what size ESD bag you have in front of you so you can place a new purchase order? No worries – we have the answer:

A. The width is measured from inside seam to inside seam. This is also your opening.
B. The length is measured from the top of the opening to the bottom of the bag.

Bonus Tip 2: Remember your ESDS items
Outside an ESD protected area, the objective of ESD protective packaging is to prevent a direct electrostatic discharge to the ESD sensitive item contained within and allow for dissipation of charge from the exterior surface. In addition, the packaging should minimize charging of the ESD sensitive item in response to an external electrostatic field and triboelectrification. If the user does not know the sensitivity of the items being used, we would always recommend static shielding packaging to be on the safe side.

In our last post, we talked about the ESD protective packaging requirements for ESD sensitive items and provided you with 6 steps to choose the correct type of packaging. We thought today we could go in a little bit more detail and introduce you to some types of packaging and how to use them. If you read our recent post on Tips to Fight ESD, you will remember how important it is to protect your ESD sensitive items when leaving an EPA. Yet, too often we see customers who have the perfect EPA, but when it comes to transporting and storing their precious components, it’s all falling apart.

Packaging required for transporting and storing ESD sensitive items
During storage and transportation outside of an EPA, it is recommended that ESD sensitive components and assemblies are enclosed in packaging that possesses the ESD control property of shielding. See our last post for more details.

Remember:

  • 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 will balance out and there will be no charge.
  • Charges repel so electrostatic charges will reside on the outer surface.

The Faraday Cage effect
A Faraday Cage effect can protect ESD sensitive items in a shielding bag or other container with a shielding layer. To complete the enclosure, make sure to place lids on boxes or containers and close shielding bags.

Cover must be in place to create Faraday Cage and shield contents.

Types of shielding packaging
The below list gives a few examples of what types of shielding packaging is available on the market. This list is by no means complete; there are many different options out there – just make sure the specifications state “shielding” properties.

  • Metal-In Shielding Bags
    ESD bags which protect ESD sensitive items. The ESD shielding limits energy penetration from electrostatic charges and discharge. They offer good see-through clarity. Available with and without zipper.

    Example of a Metal-In Shielding Bag – Click here for more information
  • Metal-Out Shielding Bags
    Integral antistatic and low tribocharging bags which will not electrostatically charge contents during movement. Bags have an aluminium metal outer layer of laminated film. Available with and without zipper.

    Example of a Metal-Out Shielding Bag – Click here for more information
  • Moisture Barrier Bags
    Offer ESD and moisture protection and can be used to pack SMD reels or trays.

    Example of a Moisture Barrier Bag – Click here for more information
  • Cushioned Shielding Bags
    These bags combine the “Faraday Cage” and mechanical protection. They shield about twice as well as normal shielding bags of equivalent size.

    Example of a Cushioned Shielding Bag – Click here for more information

Additional options for storing ESD sensitive items
Do you have the following in place?

  • ESD flooring
  • Grounded personnel (using foot grounders)
  • Grounded racking

IF (and this is a BIG IF) the above requirements are fulfilled, you can use conductive bags or containers to store your ESD sensitive items. Conductive materials have a low electrical resistance so electrons flow easily across the surface. Charges will go to ground if bags or containers are handled by a grounded operator or are stored on a grounded surface.

Conductive materials come in many different shapes and forms:

Conductive Black Bags
Tough and puncture resistant bags which are made of linear polyethylene with carbon added. The bags are heat sealable.

Example of a Conductive Black Film – Click here for more information
  • Rigid Conductive Boxes
    Provide good ESD and mechanical protection. Boxes are supplied with or without high density foam for insertion of component leads or low density foam which acts as a cushioning material.
  • PCB Containers
    Are flat based and can be stacked. They are made of injection moulded conductive polypropylene.

Again, there are many more options available on the market so make sure you do your research.

Note: we do not recommend using conductive packaging to transport ESD sensitive devices. Also, pink antistatic and pink antistatic bubble bags are not suited for storing or transporting ESD sensitive components.

Final thoughts
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.

Also, do not staple ESD bags shut. The metal staple provides a conductive path from the outside of the ESD bag to the inside. The use of a metal staple would undermine the effectiveness of the ESD bag making a conductive path for charges outside the bag to charge or discharge to ESD sensitive components inside the bag. To close an ESD bag, it is recommended to heat seal or use ESD tape or labels after the opening of the bag has been folded over. Alternatively, you can use ESD bags with a zipper.

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:
– Training
– 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:

    1. 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.
    2. 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

  1. 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?
  2. Select and test packaging materials
    Test methods are explained in ANSI/ESD S541 and will classify packaging materials as conductive, static dissipative or insulative.
  3. 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.
  4. 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.