Practical Electronics: Components and Techniques

Chapter 15. Printed Circuit Boards

This chapter presents an overview of printed circuit board (PCB) design and layout, with a focus on technique rather than specific tools. Special attention is given to topics such as PCB material, multilayer techniques, and surface-mounted components.

PCB History

Prior to the invention of printed circuit boards, assembling an electrical or electronic device was an arduous process. Insulated posts or metal tabs riveted to insulating strips provided the connection points for the various components, and insulated wires (most of the time) routed signals and voltages from one part of the circuit to another. All of it was assembled by hand. Figure 15-1 shows an example of the level of effort involved, with an image of the Atwater-Kent radio assembly line from some time in the early 20th century.

Figure 15-1. A vacuum tube radio assembly line at the Atwater-Kent factory circa 1925 (photograph from Library of Congress)

Starting in the late 1950s, the point-to-point wiring of electronic devices was gradually replaced by simple single- or double-sided printed circuit boards, as shown in Figure 15-2. The vacuum tubes are still there, but instead of wires running all over and resistors and capacitors suspended between terminal strips and solder posts, they are now mounted on a PCB. A circuit like this (which happens to be a plug-in module from a Hewlett-Packard ...