ABSTRACT
This chapter describes Printed Wiring Boards that are commonly used packaging medium for electronic circuits and systems and the design of Printed Wiring Boards. In addition to providing a framework for interconnecting components and packages, such as IC packages, Printed wiring board (PWB) can also provide a medium for component design and placement such as inductors and capacitors. The properties that must be considered when choosing PWB substrate materials are their mechanical, electrical, chemical, and thermal properties. Early PWBs consisted of copper-clad phenolic and paper laminate materials. Glass reinforced polyimide is the next most used multilayer substrate material due to its excellent handling strength and its higher temperature cycling capability. Clock traces should be considered critical and routed manually with characteristic terminations. Signal-integrity and electromagnetic compatibility considerations should be an integral part of printed circuit board (PCB) design. Signal integrity, electromagnetic interference problems, and thermal performance should be addressed early in the development cycle using proper Computer-aided design tools before physical prototypes are produced.
