Sensitive Component Protection
To protect sensitive components from accidental damage caused by ESD, two key measures must be implemented and applied at all times:
1. Sensitive components must be handled in an ESD-protected area (EAP).
2. Sensitive components must be placed in ESD-protected packaging when transferred from one EPA to another.
Essentially, an ESD-protected area (EPA) is a designated area where all surfaces, objects, people, and ESD sources are held at the same electrical potential. Achieving an EPA is simple: ensure that all materials within the area are "groundable." For example, surfaces, production containers, and tools can be covered with materials with a resistance less than 10^9 ohms. All surfaces, products, and people must then be connected to "ground." This connection is typically made through objects with a resistance between 1 and 10 megohms. Movable objects, such as containers and tools, should be placed on a grounded surface or handled by a grounded person. Any objects that cannot quickly dissipate static electricity should be kept out of the EPA.
When sensitive components are not in the equipment they belong to, they must be packaged in protective packaging during transportation or storage. In this case, the packaging must be able to perform three functions, which can be achieved by each part of the packaging separately or by the entire packaging. First, there is the innermost layer, which is in direct contact with the sensitive components, so it is also called the "intimate layer". Its ability to generate charge must be kept extremely small, and its conductivity cannot be too strong, so as not to discharge any batteries that may be contained in the components. Secondly, there must be a layer to protect the sensitive components and the innermost "intimate layer" packaging. This layer must have sufficient conductivity to shield the sensitive components from external electrostatic fields. This layer is called the "isolation layer". This layer is generally made of metal foil, so there must also be an outermost layer to protect the metal foil, so this outermost layer is called the "protective layer".