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Flexible low-cost, low-loss analog and digital multilayer circuits can be fabricated well into the millimeter-wave region thanks to a line of LCP laminates and bonding films.
flexible circuits have long been associated with polyimide films, although such materials have been limited in high-frequency performance. The R/flex® 3000 line of liquid-crystal-polymer (LCP) circuit materials from Rogers Corp. (Chandler, AZ), on the other hand, brings all the benefits of flexible substrates to microwave design, and without the high dielectric constant and poor moisture absorption that have restricted polyimide-based substrates to lower-frequency circuits.
The Rogers LCP solution is actually a multiproduct family of materials that can be used separately or together to form single-layer or multilayer high-frequency circuits. The R/flex 3000 line includes the R/flex 3600 material with LCP dielectric and single-clad copper laminate, the R/flex 3850 material with LCP dielectric and double-clad copper laminate, and the R/flex 3908 bonding film which can be used as an adhesive layer between copper and the LCP dielectric material to form high-speed, high-frequency multilayer circuits. The single-clad and double-clad laminate materials have melting temperatures of +290 and +315°C, respectively, while the bonding film has a melting temperature of +280°C.
An LCP film is essentially a thermally stable thermoplastic material. Since the R/flex 3000 materials share a low...