What's the difference among these static protection bags?

\$\begingroup\$

If you are looking for more details, kindly visit esd aluminum foil zip-lock bag.

There are two types of anti-static bag: static-dissipative (pink, red, or occasionally black) and static-discharge (silver or grey).

Static-dissipative bags are designed to remove any static build-up that gradually builds up during shipping by transferring the charge to ground (i.e. what-ever the bag is touching). However, they are not designed to handle electrostatic discharge (e.g. sparks) since they are not good conductors of electricity. Measured with a multimeter one should be able to measure a resistance through this material; I measured about 10M Ω across 1 mm. I don't have one at hand to examine but I suspect that the cross-hatched bags1 fall into this category. The red/pink bags use tallow amine as the dissipative additive while the black ones use carbon.

Conductive static-discharge bags, on the other hand, are designed to deal with sudden static discharges. They work by having a conductive metal layer (typically aluminum) usually beneath a thin, protective, often static-dissipative plastic layer. They protect the parts inside from sudden sparks by passing the current to ground (whatever the bag is touching) through the bag (and thus not the components within) with very little resistance; I measured <0.1 Ω/mm.

A third anti-static device that you may encounter is anti-static foam. This is a black, spongy, rough, and fairly firm material. This material contains a large amount of carbon and has a moderately high resistance; I measured ~100k Ω/mm. It prevents static build-up during shipment/storage at the component level. Static-sensitive devices are placed with their metal pins touching or piercing the foam (they are typically overwrapped with a bag as well). The foam ensures that all pins on a component are at the same electrical potential 2.

Dave Jones at EEVblog did a nice series of tests (YouTube) on various types of bags; well worth a watch. For preservation purposes the silver conductive bags would be the best choice. Since we're on the topic, static-sensitive devices should not be stored loose in polyethylene containers since they are very prone to building up a static charge.

1 Conjecture: I suspect that the carbon material can be printed on the bags while tallow amine needs to be mixed in to the plastic. Using a cross-hatch pattern would be a cost-saving measure.

2 One manufacturer I know ships their boards in bubble wrap envelopes that are silver on the outside and pink on the inside. In this case the outer layer protects against sudden discharges (i.e. sparks) while the mildly-conductive inner layer keeps all pins/traces on the enclosed board at the same electrical potential.

Posted: January 23rd, 2020 Author: Jim Higgs

TABLE OF CONTENTS

Static Shielding Bags
How Do Static Shielding Bags Work?
What Are Static Shielding Bags Used For?
Pros
Cons
Types of Static Shield Packaging
Anti-Static Bags
How Do Anti-Static Bags Work?
What Are Anti-Static Bags Used For?
Pros
Cons
Types of Anti-Static Packaging
Static Shielding Bags Vs. Anti-Static Bags

The company is the world’s best shrink film rolls wholesale supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

Anti-static bags are only static dissipative, whereas static shielding bags are both static dissipative and static shielding by means of a Faraday cage. When a static charges come in contact with anti-static bags, the charge is quickly shed with no build-up of static — however, the charge could penetrate the wall of the bags and contact the packaged devices. Static shielding bags for electronics and similar devices provides a shield for the packaged devices from penetrating static.

Anti-static bags and static shielding bags will protect electronics from electrostatic discharge (ESD). ESD and moisture could impact the functionality of  electronic devices and can shorten their life. Proper packaging will keep your contents dry and will protect electronics from static discharge.

We will help you discover which type of static resistant bag is right for the transportation, shipping and handling of your electronics item. Below are the unique features, materials and use of both anti-static and static shielding bags.

WHAT ARE STATIC SHIELDING BAGS

Static shielding bags can be used for shipping, transportation or storage of static sensitive electronics. Some devices are so sensitive to electricity that even the static shock from human touch could limit functionality. Sealed static shielding bags will guard your electronic devices against ESD related damage by eliminating static build-up created by the rubbing of surfaces, also called tribocharging. Additionally, by the Faraday cage effect, charges are prevented from penetrating the wall of the bags.

HOW DO STATIC SHIELDING BAGS WORK?

An ESD can occur when there is an excess buildup of static electricity. The material within static shielding bags contain multiple layers, including a metalized protective layer. The metalized layer creates a Faraday cage effect around the packaged electronic devices.

The Faraday cage effect acts as a shield against external static electric fields, in addition, the static dissipative coating on both the inside and outside layer of the bag continually remove and prevent the build-up of static electricity.

WHAT ARE STATIC SHIELDING BAGS USED FOR?

Static shielding bags prevent the buildup of static electricity and are ideal for transporting and packing static sensitive items such as:

• Printed circuit boards (PCBs)
• Disk drivers
• Resistors
• Memory cards
• Populated circuit boards
• Processors
• Semiconductors
• Other sensitive integrative circuits (ICs)

PROS

Static shielding bags provide an extra measure of protection when compared to anti-static bags. Static shielding bags protect electronics from exposure to static electricity and also protect electronics against an ESD from penetrating the wall of the bag. The multi-layer construction provides a good moisture barrier when the bag is heat sealed closed. Static shielding bags can also be a part of a fire prevention program where strong static charges are in proximity to flammable items.

CONS

Static shielding bags must be completely sealed or closed in order to be fully effective. It’s important to exercise an extra measure of caution when shipping sharp objects that could compromise the integrity of the bag.

TYPES OF STATIC SHIELD PACKAGING

Static shielding bags are both static dissipative and static shielding, but there is another level of protection to be had in a Moisture Barrier Bag (MBB). An MBB provides all the benefits static shielding bags do, plus protection against moisture or water vapor. The bags must be heat sealed and sometimes vacuum sealed. Also MBB are typically much thicker and have greater puncture resistance than static shielding bags.

Want more information on electro static discharge film? Feel free to contact us.