Type	Features
Electro-deposited(ED) Copper foil	General application, suitable for static or low flexing requirements
Roll-annealed(RA) Copper foil	High flexing ability, suitable for dynamic application

Copper is sandwiched between dielectric base material and coverlay, the identical circuits protection materials position the circuits pattern in a mechanically neutral zone.

Rolled annealed (RA) copper is recommended for high dynamic application such as optical pick-up head, printer head and disk drive because of its superb flexural endurance characteristic.

It should be borne in mind that most flexible circuits are customised three dimensional interconnection systems with one-time fixing and do not require high flexural endurance. Therefore Electro-deposited Copper (E.D. copper) is adequate for most applications. Another alternative copper type which is gaining popularity is the use of Dyncamically Flexing ED Foils, or DF ED. It offers typically more controllable etch rates and straighter trace walls which is sometimes compatible to RA foils with lower cost.

The selection of copper type will depend on the current carrying and other electrical requirements of the circuit. Conductor materials other than copper are also available. Other conductor materials are available such as aluminium, nickel, nichrome and beryllium copper.

While these other materials are available, their use is very rarely called for.

Customer reference/客户