TABLE OF CONTENTS Modern electronic packaging has become very complex. Interconnections are pushed more into lower levels of packaging. The choice of which packaging technology to use is governed by many factors: cost, electrical requirements, thermal requirements, density requirements, and so on. Material also plays a very important role. All things considered, PCBs play very important roles in electronic packaging.1
Since the invention of printed circuit technology by Dr. Paul Eisner in 1936, several methods and processes have been developed for manufacturing PCBs of various types. Most of these have not changed significantly over the years. However, some specific trends continue to exert major influences on the types of PCBs required and the processes that create them:
Computers and portable telecommunications equipment require higher-frequency circuits, boards, and materials, and also use more functional components that generate considerable amounts of heat that need to be extracted.
Consumer products have incorporated digital products into their design, requiring more functionality at ever lower total cost.
Products for all uses continue to get smaller and more functional, driving the total circuit package itself to become more dense, causing the PCBs to evolve to meet these needs.
These will be discussed in this chapter, along with the traditional board structures and processes. The terms printed circuit board, PCB, and board will be used synonymously. Also, the words laminate, substrate, and panel will be used interchangeably.
