Category Archives: Bags and Labels

Best Storage Conditions for PCBs

Most people are aware of the dangers ElectroStatic Discharge (ESD) can pose on 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 stuff it with electronic (semiconductor) devices, it becomes susceptible according to each of the individual’s susceptibility.
However, there is another risk factor many operators forget: moisture.
So, today’s blog post is going to address both issues and will explain how you can protect your PCBs from both when storing them.

The problem with moisture
By now 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.

The problems moisture causes in SMDsMoisture from air diffuses inside the plastic body & collects in spaces between body & circuit, lead frame and wires. Expanding vapour can crack (popcorn) the plastic body or cause delamination.

Storing PCBs
All PCBs should be stored in a moisture barrier bag (MBB) that’s 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 standardised 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)

Moisture Barrier Bag (MBB)

Moisture Barrier Bags (MBB) work by enclosing a device with a metal or plastic shield that keep moisture vapour from getting inside the bag. They have specialised layers of film that control the Moisture Vapour Transfer Rate (MVTR). The bag also provides static shielding protection.

204519
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 vapour (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 vapour. The recommended amount of desiccant is dependent 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.

Humidity Indicator Cards (HICs)


Humidity Indicator Cards (HICs) are printed with moisture sensitive spots which respond to various levels of humidity with a visible colour 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


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.

 

Creating a dry package
Now that you know the components of a dry package, you’re probably wondering: but how do I put it all together? Not to worry – we’ve got you covered! If you follow these steps, you will create a secure dry package and your PCBs will be protected – against ElectroStatic Discharge and moisture.

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 - Step 1

Place the MSL label on the bag and note the proper level on the label.
Dry Packaging - Step 2

Place the tray stack (with desiccant and HIC) into the moisture barrier bag.
Dry Packaging - Step 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 - Step 4

Now your devices are safe from moisture and ESD.
Dry Packaging - Step 5

Do you use moisture barrier bags in your facility? What are your experiences? We’d love to hear from you in the comments!

And that’s a wrap! Just to let everyone know that we will be taking a little summer break over the next few weeks so there won’t be any new posts going up until the end of September. Don’t miss us too much…

 

 

6 Steps to defining ESD Protective Packaging Requirements for ESD Sensitive Items


If your company has an ESD Control Programme per EN 61340-5-1 in place, you need to define ESD protective packaging for ESD sensitive items (ESDs). But where do you start? Don’t panic – we’re here to help!

What is ESD Protective Packaging?

ESD Protective Packaging comprises all “items and materials that provide intimate protection for ESDS parts during all phases of handling, shipping and storage”. [EN 61340-5-2 User Guide clause 4.8.1 Introduction and purpose]
You don’t need to worry about secondary or exterior packaging unless it’s used for ESD protection purposes.

37150Example of ESD Protective Packaging – Protektive Pak Inplant Handlers

Why do you need ESD Protective Packaging?

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.
An ESD protective packing system’s basic function is to make up the difference between the ESD sensitivity of the product and the level of threat that exists in the distribution environment. For example, if the product has a human body model sensitivity of 100 V and the people that will be handling the package are known to have a maximum of 1 000 V on their bodies, then a package shall be selected that will make up the difference between the product’s ESD sensitivity and the distribution environment.” [EN 61340-5-2 User Guide clause 4.8.3 Selecting/designing the right package]
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 for ESDS within the plan based on IEC 61340-5-3. Packaging, when required, shall be defined for all material movement within EPAs, between EPAs, between job sites, field service operations and to the customer.” [EN 61340-5-1 clause 5.3.5 Packaging]

Choosing your ESD Protective Packaging

A number of factors need to be taken into consideration when choosing your ESD protective packaging including “the ESD sensitivity of the product as well as the expected distribution environment hazards.” [EN 61340-5-2 User Guide clause 4.8.3 Selecting/designing the right package]

Protektive Pak Circuit Board Shippers with Pink or Black FoamExample of ESD Protective Packaging – Protektive Pak Circuit Board Shippers

The User Guide EN 61340-5-2 recommends the following steps to implement your ESD Protective Packaging:

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 analysing 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, 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 evacuated from the package before shipment.

3. 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?

4. Select and test packaging materials
Test methods are explained in EN 61340-5-1 and will classify packaging materials as conductive, static dissipative or insulative.

5. Design a packaging system
Once 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 User Guide, the following general rules apply:

  • If the package is primarily used to transport product in an ESD protected environment then a low charging, static dissipative package may suffice.
  • If the product is moving between ESD protected areas (uncontrolled environment) a low charging, discharge shielding package may be required.
  • When the package is shipped into a totally uncontrolled environment a low charging discharge shielding package is recommended.

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.

6. 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. If you want to learn more about the different types of options, we recommend reading this post.
Also, remember that ESD packaging should be marked. This post will help you finding the correct symbol for your application.

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Example of ESD Protective Packaging – ESD Bags

Do you currently use ESD Protective Packaging? Do you use bags or boxes or something else? How did you choose your ESD Protective Packaging?

What is a Faraday Cage?

We have mentioned the term “Faraday Cage” many times on this blog before – for example when talking about the transport and storage of ESD sensitive items or the role of ESD lab coats in ESD Protected Areas. When discussing ESD protection, the concept of the “Faraday Cage” will always come into play. But what exactly is it? Read on to find out…

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.
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 Striking an AiroplaneLightning striking an airplane

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’.
ESD control products that provide a Faraday Cage or shielding include Statshield® Metal-In and Metal-Out Shielding Bags or Protektive Pak™ impregnated corrugated boxes with shielding layer when using a lid.

ESD shielding packaging is to be used particularly when transporting or storing ESD sensitive items outside an ESD Protected Area. Per Packaging Standard EN 61340-5-3 clause 5.3 Outside an EPA “Transportation of sensitive products outside of an EPA shall require packaging that provides both:
dissipative or conductive materials for intimate contact;
– a structure that provides electrostatic discharge shielding.

37150.jpgProtektive Pak® In-Plant Handler

ESD Smocks create a Faraday Cage effect around the torso and arms of the operator and shields charges from the operator’s clothing from damaging ESD sensitive devices. (Technically, suppressing the electrical field from clothing worn underneath).

 

Examples of ESD Smocks

There are standard tests measuring the energy penetration of electrostatic discharges to the interior. The Shielding test method per Packaging standard EN 61340-5-3 is ANSI/ESD STM11.31 and the required limit is less than 50 nanoJoules of energy.

Definitions from the ESD Association Glossary ESD ADV1.0 include: Faraday Cage “A conductive enclosure that attenuates a stationary electrostatic field.
Electrostatic discharge (ESD) shieldA barrier or enclosure that limits the passage of current and attenuates an electromagnetic field resulting from an electrostatic discharge.
Electrostatic shieldA barrier or enclosure that limits the penetration of an electrostatic field.

Are you handling ESD sensitive devices? 3 symbols you need to know!

If you’ve been handling ESD sensitive devices for a while, you’ve probably come across the different ESD symbols already. But do you know the difference(s) and when to use them? No? Read on!
Are you new to ESD protection or have just taken over responsibility for an existing ESD programme? Congratulations – you’ve come to the right place! Keep on reading!

1. ESD Susceptibility Symbol

The ESD Susceptibility Symbol is the most commonly known symbol which consists of a yellow hand in the act of reaching, deleted by a bar; all within a black triangle. It is intended to identify devices and assemblies that are susceptible to ESD.

ESD Suceptibility SymbolThe ESD Susceptibility Symbol

When to use the ESD Susceptibility Symbol

The ESD Susceptibility Symbol is correctly used as follows:

  • on individual components and related documents to state: ‘this device is static sensitive; do not touch without appropriate precautions’
  • on assemblies and related documents to state: ‘includes static sensitive components; take appropriate precautions’
  • as part of a sign identifying an area where sensitive devices are handled; to warn all who approach it that precautions are required

Colour of the ESD Susceptibility Symbol

The colour is optional except “the color red shall not be used because it suggests a hazard to personnel.” The preferred colour is a yellow hand and slash on a black triangle.

2. ESD Protective Symbol

Just like the ESD Susceptibility Symbol, the ESD Protective Symbol has a reaching hand in a triangle. However, note the arc and missing slash through the triangle! Because of these differences it has a very different meaning.
This symbol should be on ESD protective products identifying a specialty product that has at least one ESD control property.
The ESD Protective Symbol is also called the ESD Packaging Symbol.

ESD Protection SymbolThe ESD Protective Symbol

If a letter is under the triangle, it should identify the most important ESD control property:

  • L = Low Charging
  • D = Static Dissipative
  • C = Conductive EPA (for use in the ESD Protected Area)

When to use the ESD Protective Symbol

The ESD Protective Symbol may be used to identify items that possess at least one ESD control property:

  • Low Charging (formerly referred to as astatic or antistatic)
  • Resistance (Conductive or Static Dissipative) able to remove electrostatic charges when grounded
  • Discharge Shielding

Colour of the ESD Protective Symbol
The colour is optional except “the color red shall not be used because it suggests a hazard to personnel.” The preferred colour is a yellow hand and slash on a black triangle; the arc should be black.

3. ESD Common Ground Point and Earth Bonding Point Symbol
These two symbols identify where all ESD elements at an ESD workstation should be connected. There is a newer and older symbol; they are very different but basically have the same meaning:

  • The Earth Bonding Point Symbol has the earth ground symbol and concentric circles around the ground snap, plug or jack.
  • The ESD Common Ground Point Symbol has concentric circles with thick circle around the ground snap, plug or jack.

Both symbols should include text identification.

ESD Common Ground Point and Earth Bonding Point Symbol

 

Symbol artwork for all of the above symbols can be downloaded at no charge from the ESD Association.

Use the comments section below for any questions you may have.

Reference: EN 61340-5-1, CLC/TR 61340-5-2 ESD User guide, and Symbol standard ANSI/ESD S8.1.

Why you should worry about desiccant and humidity indicator cards!

Let’s talk “desiccant” and “humidity indicator cards” this week! “Desi-what” I hear you say???
Seems like we chose the right subject…!

But let’s rewind a little at this point: A few months ago we published a post on Moisture Barrier Bags (MBB) and ESD Control. The article described that Moisture Barrier Bags shield (no pun intended here!) ESD sensitive devices from 2 potential risks:

  1. The faraday cage created when using these bags correctly protects contents from ESD Damage.
  2. Specialised layers of film controlling the Moisture Vapour Transfer Rate (MVTR) also protect contents from moisture.

13950Moisture Barrier Bags

The blog post went on to explain that “desiccant” and “humidity indicator cards” must be used for proper moisture protection.
So what are “desiccant” and “humidity indicator cards” and how are they used? These are the questions we’d like to clarify with 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.

204519A desiccant pouch

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?

A word of warning before we move forward – the following calculations may look a bit daunting at first sight. But honestly, once you’ve read through it all and calculated a couple of examples, you’ll be fine! Promise!!!
There are 2 different methods you can use – so let’s dive right in:

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

Phew – told ya’ it wasn’t that bad! Now that we’ve covered the desiccant, we’ll take a quick look at humidity indicator cards. And I really mean “quick” because they’re much easier to explain/use….

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 colour 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.

204502Example of a humidity indicator card

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. 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.

 

Well, that’s it – that’s all we have for today! Did we answer all your questions? If not, let us know your questions in the comments below!

5 Tips for using shielding bags

Today we have a short and sweet but nonetheless important post for you guys. Following our last post on choosing the right ESD bag, we’ll be focusing on shielding bags below as they are the most commonly used ESD bags.
There are a few “dos and don’ts” you should keep in mind to ensure you get the most from your shielding 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 using your shielding bags:

Enclose your ESD sensitive item with the 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 advise ensures a continuous Faraday Cage is created which provides electrostatic shielding. This is the only way to ensure ESD sensitive devises placed inside the shielding bag are protected.

Enclose Shielding BagsEnclose your ESD sensitive item

Please do not staple your shielding bag. Metal staples 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.

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 working surface before removing the product. This will remove any charge that might have accumulated on the surface of the shielding bag.

Remove Static ChargesRemove charges

Don’t 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.

Don't Overuse Shielding BagsDon’t overuse shielding bags

Shielding bags are no working surface

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

Shielding Bags are no ESD Worksurface
Don’t use shielding bags as your ESD working surface

A shielding bag is No “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”

Enjoy your shielding bags!

2 steps to choosing the right ESD bag

In the past we spoke about some types of ESD bags (antistatic bags vs. dissipative bags, moisture barrier bags). Today we want to focus on the whole 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 you say? 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 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. 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 x x Both
Bubble Shielding x x Both
Pink Antistatic x Inside only
Pink Antistatic Bubble x x Inside only
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. They offer good see-through clarity. Available with and without dissipative zipper.
    metalinzipper

    Metal-In Shielding Bags
  2. Metal-Out Shielding Bags
    Integral antistatic and low tribocharging bags which will not electrostatically charge contents during movement. Bags have an aluminum metal outer layer of laminated film. Available with and without dissipative zipper.
    202100

    Metal-Out Shielding Bags
  3. Moisture Barrier Bags (MBB)
    Offer ESD and moisture protection and can be used to pack SMD reels or trays.
    90700

    Moisture Barrier Bags (MBB)
  4. Bubble Shielding Bags
    These bags combine the “Faraday Cage” and mechanical protection. They shield about twice as well as normal shielding bags of equivalent size.
    12800

    Bubble Shielding Bags
  5. Pink Antistatic Bags
    Economical bags which are made of polyethylene. They are for use with non-ESD sensitive items destined for use in an EPA. Available with and without zipper.
    203065

    Pink Antistatic Bags
  6. Pink Antistatic Bubble Bags
    ESD bags which are made of pink-tinted, amine-free, antistatic polyethylene. They provide good mechanical protection and are for use with non-ESD sensitive items. The 25mm flap has a self-adhesive strip to close the bags.
    202530

    Pink Antistatic Bubble Bags
  7. Conductive Black Bags
    Black conductive film is made of virgin low density materials with black conductive compound to achieve high toughness and strength.
    203600

    Conductive Black Bag

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:

  1. Shielding, Black Conductive and Pink Antistatic Bags
    A. Bag Width = Item’s Thickness + Item’s Width + 25mm
    B. Bag Length = Item’s Thickness + Item’s Length + 50mm
  2. Moisture Barrier Bags (MBB)
    A. Bag Width = Item’s Thickness + Item’s Width + 25mm
    B. Bag Length = Item’s Thickness + Item’s Length + 76mm
  3. Pink Bubble and Bubble Shielding 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 quite 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 of 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 seem to inside seem. 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, static shielding packaging should be used.

 

Do you have any more questions or require a quote for ESD bags? Vermason can help so make sure you get in touch!

Storage and Transport of ESD Sensitive Items

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We thought today we could focus on ESD during storage and transport. If you have 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.

1. Packaging required for transporting and storing ESD sensitive items

During storage and transportation outside of an EPA, we recommend that ESD sensitive components and assemblies are enclosed in packaging that possesses the ESD control property of shielding.

Remember:

  • In ‘shielding’ we utilise 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.


2. 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.

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

3. 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 dissipative zipper.
  • 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 dissipative zipper.
  • Moisture Barrier Bags
    Offer ESD and moisture protection and can be used to pack SMD reels or trays. Check out this post for more information on MBB and ESD Control.
  • Bubble Shielding Bags
    These bags combine the “Faraday Cage” and mechanical protection. They shield about twice as well as normal shielding bags of equivalent size.
  • Component/Circuit Boards Shippers
    These boxes offer an efficient way of shipping or storing ESD sensitive circuit boards and other items. They provide ESD shielding with the lid closed. The foam cushioning reduces stress from physical shock.
  • In-Plant Handlers/Storage Containers
    Shield ESD sensitive items from charge and electrostatic discharges (with lid in place). They provide ESD and physical protection for ESD sensitive circuit boards.


4. Additional options for storing ESD sensitive items

Do you have the following in place?

  • ESD flooring
  • Grounded personnel (using foot grounders). Read this post for more information on how to ground moving personnel.
  • Grounded racking

TEAMOperator wearing foot grounders

IF (and this is a BIIIG 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.
  • 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.

5. 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.

Picture5Sealing ESD Bags the correct way

One final word of warning:
When ESD sensitive items are unpackaged from shielding bags or other containers, they should be handled by a grounded operator at an ESD workstation

 

 

Are antistatic and dissipative bags the same?

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Antistatic is an ESD control property properly referred to as “low charging”. This is an important property for all bags used inside or outside of an ESD protected area (EPA). Specifically, it is important that the inside of the bag is low charging. This ensures that when the ESD Sensitive Device is inserted into the bag or otherwise moves, there is minimum electrostatic charge generation.

Dissipative is the electrical property of resistance so when grounded electrostatic charges will be removed to ground. This is an important ESD control property as the bag can be grounded; being dissipative provides an electrical path for an electrostatic charge to dissipate from the bag.

Picture5Shielding Bag used in an ESD Protected Area (EPA)

All bags inside the ESD Protected Area [EPA] should be both low charging and dissipative whether packaging ESD sensitive item or non-ESD sensitive items.

Packaging Standard EN 61340-5-3 clause 5.3 Outside an EPA:
“Transportation of sensitive products outside of an EPA shall require packaging that provides both:
a) dissipative or conductive materials for intimate contact;
b) a structure that provides electrostatic discharge shielding.

NOTE 1: If electrostatic field shielding materials are used to provide discharge shielding, a material that provides a barrier to current flow should be used in combination with the electrostatic field shielding material.
NOTE 2 Dissipative materials are preferred for intimate packaging in situations where charged device model (CDM) damage is a concern.”

View our offering of ESD Bags HERE.

What happens if you staple ESD Bags shut?

Question:

What happens if you staple ESD Bags shut? Does that damage the ESD Bag’s effectiveness? What if the ESD Bag is heat sealed shut & a staple on the seam is used to attach paperwork?

Answer:

Vermason ESD Shielding Bags have a layer of metalized film which creates continuous conductive enclosure or Faraday Cage to provide electrostatic shielding protecting the ESD sensitive devices placed inside the Bag. The use of stapling to close ESD Bags is counter productive and not recommended. 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 outside the Bag to charge or discharge to ESD sensitive components inside the Bag.

To close the ESD Bag, it is recommended to heat seal, or use Vermason ESD Labels after the opening of the bag has been folded over.

To view Vermason ESD Labels Click Here

Or to view Vermason Antistatic Tape Click Here

Carefully locating the staple to only the seam of the Vermason Statshield® Bag would theoretically make it part of the “continuous conductive enclosure” and be acceptable. However, we are not aware of any end user using this method and cannot recommend it. The staple would be an exposed conductor that could charge or discharge to ESD sensitive devices.

To ask an ESD Question Click Here.

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