Ordinary bags can be just fine for items like shirts, books, or sets of paper. However, the same bag can become a bad decision when considering a circuit board or computer part. Static electricity can destroy highly sensitive electronics in a way that leaves no visible mark or sparks.
Static electricity is also known as electrostatic discharge (ESD). ESD occurs when there is movement of electrical charges from one object to another. Many people generate static simply by walking across a floor or by rubbing against certain types of packing materials. Once you have created static and reach out and touch a small sensitive area, the component may immediately fail or fail sometime later.
You should check if the product you are about to place into a poly bag is listed as being sensitive to Electrostatic Discharge (ESD) prior to selecting your bag. This information should come directly from the manufacturer, engineer, or parts listing. One should never make assumptions based on size, as many small components will be much more sensitive to static electricity than larger devices which appear to be fragile.
Anti-static and “static shielding” are often confused. Anti-static refers to a material that will produce less electrical charge when rubbed against other materials. While these bags will reduce the generation of static electricity, they typically don’t provide complete protection against external sources of static electricity. Static shielding bags include a layer that routes the electric current away from the part rather than allowing it to pass through.
When storing loose circuit boards and sensitive parts together, placing each part within a sealed static-shielding bag provides maximum protection during shipping and storage. Each part must be completely contained within the bag and the seal must be completed as recommended. If a circuit board is placed through an open end of a bag, it will not receive the full benefit of the protective layer provided by the shielded bag.
As with all electronic components, a secondary concern related to moisture can occur. A static control bag does not serve as a moisture barrier. Therefore, when a component requires both protection from static electricity and protection from moisture, you must select a bag that meets both requirements and store according to the manufacturer’s instructions. Dry packets are best used only as per the product design specifications.
While the use of an anti-static or static shielding bag represents an important aspect of an ESD program, it represents only one step toward achieving effective control over static electricity. Employees working with sensitive parts must also utilize grounding wrist straps, static-free work mats and follow specific handling procedures prior to inserting their parts into their bags. Static can be generated while handling circuitry (i.e., by touching pins or sliding circuit boards across tables), causing harm even before the parts are enclosed in their bags.
Do not overlook static-shielded bags that have been previously used. These bags may be damaged in ways that are imperceptible. NASA warns against the reuse of anti-static bags containing sensitive space-related parts due to potentially damaging wear. Your company must develop policies regarding the reuse of its own bags and adhere to those policies; discard any reused bags whose histories are not well-documented.
Display a label indicating ESD compliance in an area easily viewed by employees who may encounter such bags. Train your employees on what these labels represent and maintain separate areas for your approved bags to avoid mixing them with ordinary plastic film bags during peak periods of activity. Although purchasing an ESD-compliant bag will add expense relative to purchasing plain film bags, it could ultimately save your company money compared to repairing defective products, losing valuable data, performing costly repairs and receiving returned goods that are very expensive.
