3M has introduced flexible circuits based on liquid crystal polymer (LCP) dielectric film.
3M claims that the new LCP Flex Circuits offer dimensional stability, chemical resistance and high-frequency dielectric properties that are superior to those of polyimide, which is the most commonly used flex circuit substrate.
The LCP flex circuits have a low water absorption rate of 0.1 percent versus polyimide’s 1-3 percent rate. LCP film, a thermoplastic polyester, also has a high temperature tolerance, making it compatible with soldering and wire bonding operations.
3M’s process overcomes difficulties that have limited acceptance of LCP flex circuits until now. The process creates fine-line features in a roll-to-roll format without adhesives or physical punching. It includes 3M-developed techniques for vacuum metallisation, which produces fine lines without delamination due to undercut, and chemical etching, which allows the use of cantilevered leads and other exposed metal features.
3M is providing customised prototypes of LCP flex circuits to selected electronics customers. The company will present technical data on the reliability of its LCP flex circuits at the International Conference on Advanced Packaging and Systems, March 10-13, 2002 in Reno, Nevada.