Chapter 4 – Process Challenges and System Applications in Flex
By William E. Burdick and Kevin M. Durocher

            Thin, fine-pitch flexible interconnection structures require unique considerations that, in turn, create a variety of challenges. Chapter 4 describes many of the challenges associated with flexible circuit technology and potential ways to deal with them, discussing the necessity of clean process facilities and tooling, handling of thin dielectrical materials, in-process monitoring, post-fabrication testing and electrical function testing. Images of potential defects are provided to enhance the understanding of what it takes to make quality flexible circuits.
Since their inception as a simple interconnection alternative to discrete wires, flexible printed circuits have evolved into a cornerstone technology of high-density interconnect, used within subsystems, as well as for system interconnect. Chapter 4 educates and informs as to how flexible circuit technology must continue to develop and expand its capabilities to optimize flex integration and meet market demands.