New Materials for Rigid-Flex Printed Wiring Boards

The rigid-flex printed wiring board (PWB) is the state-of-the-art in electronics circuitry development. It offers the most in board configuration flexibility for making optimal use of space in electronic packaging, improving performance of electronics packages, and reducing maintenance. However, adhesive failure of the rigid-flex materials during use has degraded the performance of military avionics systems. Adhesive failure is often caused by differences in the coefficient of thermal expansion and moisture absorption. The objective of this research topic is to investigate alternatives to the epoxies, polyimides, and adhesives currently used in rigid-flex PWBs. The focus will be on high-temperature thermoplastics. High-performance engineering thermoplastics such as polyetheretherketone (PEEK), polyetherimide (PEI) and liquid crystal polymers (LCPs) are less hygroscopic and tend to be more dimensionally stable than materials that are currently used. Because thermoplastic materials are remeltable, QUEST proposes to eliminate the use of adhesives by using simple fusion bonding techniques to join rigid-flex PWBs. This would improve adhesion by eliminating problems with material compatibility and differences in coefficient of thermal expansion. Additional benefits of using thermoplastics and fusion bonding techniques are decreased moisture absorption, increased dimension stability, improved mechanical properties, simplified manufacturing, and the infinitie storage life of raw materials. OPTION TASK: None submitted.