ESD Static Shielding Bags are commonly used for the packaging of electronic components to prevent damage caused by electrostatic discharge events that electronic devices can be prone to. In this article, we will discuss a few of the finer points that will hopefully point you in the right direction when selecting an ESD static shielding bag.
Remember, at any time you can visit our ESD Shielding products using the links down below
Desco Static Shielding Bubble Bags
Desco Static Shielding Moisture Barrier Bags
Desco Metal-In Static Shielding Bags
Desco Fold Top Static Shielding Bags
Desco Metal-In Zip Top Static Shielding Bags
Protektive Pak Pink Poly Bags
The terms “static shielding” and “anti-static” seem to be used as one in the same in many instances. However this is not the case, there are actually major differences between static shielding and and anti-static materials. Ordering the incorrect one for your application could mean product damage.
If the bag you're considering is a Static Shielding Bag, that means it prevents the build up of static electricity (meaning they have anti-static properties), it also means that the bag will protect from electrostatic discharge or ESD for short. These bags are made of multi-layer materials which create what is called a Faraday Cage that protects components from ESD.
Unlike anti-static bags, static shielding bags protect components from static charges both inside and outside of the bag. In order to provide ESD protection, material is fashioned into a bag or enclosure of some sort and products are sealed inside the bag. No seal, no guarantee of protection. And be sure to pad sharp components and don’t use staples. They can compromise the static shielding properties of the bags.
Another class of static shielding bags are moisture barrier shielding bags (MBB). These materials shield from electromagnetic interference (EMI) as well as radio frequency interference (RFI) and static. This is mainly accomplished by using a much thicker metal layer, inhibiting the moisture vapor transmission rate (MVTR) by a factor of over 20 times more compared to ordinary shielding bags.
Anti-static bags ONLY prevent the build up of static electricity. The material itself will not generate or hold a charge, so cannot be a carrier that introduces static into a static controlled environment. These materials do not protect from electrostatic discharge (ESD). Anti-static bags and materials are ideal for packaging non-static sensitive parts used in electronics manufacturing, like nuts and bolts or manuals. Many people think of pink polyethylene bags when they think of anti-static bags. Pink poly anti-static bags should never be used as the only packaging to protect electronic components from electrostatic discharge.
Is There a Difference Between an Anti-Static Bag and a Static Shielding Bag?
No. Static dissipative ESD bags provide static dissipative materials that slowly drain charge. In ESD areas, these bags simply hold documents or other non-sensitive items without transferring any charges from a non-ESD safe area.
Clear static dissipative bags are not safe for components, as a component may absorb an ESD shock without the protection of a shielding bag. This is why, only non-ESD sensitive products are used with plain static dissipative bags.
As your figuring out which ESD Static Shielding product to go with for your application, you need to be clear about the use of your ESD bag as well as the environment it’s being used in. Ask yourself the following questions:
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 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: 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.
ANSI/ESD STM11.31 provides a method of evaluation for the energy transferred from the package to the interior.
The ability of some packages to provide discharge shielding may be evaluated using ANSI/ESD STM11.31 which measures the energy transferred to the package interior. A material’s low charging properties are not necessarily predicted by its resistance or resistivity.
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