ABSTRACT
The use of copper foils as a conductive material for either rigid or flexible printed wiring boards is well-known. Two types of foils in use today are either electrodeposited (ED) or wrought (sometimes called rolled annealed [RA]) copper foils. Specific foil properties and end user applications have led to a further categorization of these two types into grade classification (IPC-4562). Over the years, particular types and grades have been specific for consumer, commercial, or military markets. As a general rule, electrodeposited foils, identified as grades 1 to 4, are utilized on rigid boards (single, double, composite, and multilayer boards). Flexible circuitry, on the other hand, utilizes both electrodeposited and wrought copper foils (grades 2, 5–8) for their applications. Although the IPC lists grades 4, 6, 10, and 11, these foils are not readily available for commercial use.
