Five Steps to Static Electricity Elimination
1. Incorporate ESD Protection into Components and Products: Design your components, products, and assemblies to more effectively prevent the effects of electrostatic discharge (ESD). If possible, use components that are insensitive to ESD, or provide appropriate input protection for those components that are sensitive to ESD. Paradoxically, advanced manufacturing technologies mean smaller and more complex geometries, which are often more sensitive to ESD. However, the more ESD controls you incorporate into your product design, the fewer problems you will encounter later.
2. Eliminate ESD-Generating Materials and Processes: Obviously, product design is not the complete answer. You cannot escape ESD-generating components and products, but you can reduce or eliminate the generation and accumulation of ESD. Start by minimizing or eliminating many ESD-generating processes or materials in the work environment, such as common plastics. Because static electricity does not occur between materials that maintain the same potential or zero potential, processes or materials in the work environment should maintain the same ESD potential. Typically, these conductive or dissipative materials should be electrically connected to the same common ground, such as an electrical ground wire. Additionally, provide grounding to ESD wrist straps, floors, or workbench surfaces to safely reduce the generation and accumulation of discharge.
3. Dispersing or Neutralizing Static Discharge: Since it is impossible to completely eliminate all static electricity, our third principle is to safely disperse or neutralize any potential electrostatic discharges. Appropriate grounding and conductive or dispersive materials play a key role. For example, a worker entering the work environment with static electricity can discharge it by wearing an anti-static wrist strap or anti-static controlled work shoes and stepping over an anti-static floor mat, transferring the static electricity to the ground instead of discharging it onto sensitive components. For some objects, such as ordinary plastics and other insulators, grounding cannot eliminate electrostatic discharge. Typically, ionization is used to neutralize discharges on these insulating materials. The ionization process generates positive and negative ions, which are attracted to the surface of the discharging object, thus effectively neutralizing the electrostatic discharge.
4. Providing Physical Protection Against Electrostatic Discharge: Our fourth principle is to prevent potential electrostatic discharges from contacting sensitive components and assemblies. One method is to provide appropriate grounding or shunting for components and assemblies, diverting any discharge away from the product. A second method is to package and transport sensitive components in appropriate packaging materials. These materials effectively shield the product from static electricity, reducing static electricity generated by any movement of the product within the packaging. 5. Inspect your process and environment. For example, use a field meter to detect the presence of electrostatic fields that could potentially cause electrostatic hazards. Measurement is the safest method. Identifying and quantifying the areas that truly require ESD protection allows you to focus on the areas of greatest concern. Additionally, you can identify areas that will not cause ESD hazards, saving you the expense of unnecessary protection.
These five principles form the basis of an effective ESD control procedure. They help in selecting appropriate materials and procedures to effectively control ESD. In most cases, an effective procedure will involve all these concepts. In developing a control procedure, identify the sensitive components, the sensitivity levels, and the operations that pose an ESD hazard to them. Then consider which concepts will protect these components. Finally, select and implement a combination of procedures and materials that accomplish this task.