Printed Circuit Boards

Written by Adam Blau
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For many, the inner workings of electronic devices are something of a mystery. You flip a power switch, a light appears, and the machine does exactly what you expect, whether it's a transistor radio, a microwave oven, or a high-powered computer. It may seem like some sort of modern-day magic is behind the operation of most household appliances.

A quick peek into virtually any of these units will reveal that the "magic" is, in fact, the result of extensive processing of an electric current across a circuit board. As current passes through the various components attached to the board, each unit performs its task in the overall scheme of the whole device. Current passes through a light-emitting diode when an internal switch is activated, and it appears to an outside viewer that it comes on by flipping the power switch.

Circuit boards range in complexity from the very simple (in the case of a no-frills radio receiver) to the extremely intricate (in the case of a computer). The simplest boards are called "breadboards." These are surfaces on which components such as resistors and capacitors are attached and interconnected with wires. While such surfaces are satisfactory for simple circuits, a more efficient and compact solution is necessary for more complex circuits.

Introducing the Printed Circuit Board

Breadboards, alas, can get to be somewhat unwieldy and bulky. These characteristics are usually the result of wire connections to the board. In order to reduce the overall size and increase the efficiency of a circuit board, it can be helpful to make the method of component connectivity more compact. It is possible to effectively imprint the wires themselves into the surface of the circuit board.

On a printed circuit board (PCB), there is a web of conductive material (usually copper) etched onto the surface. External components such as transistors and integrated circuits are soldered directly onto the board's surface, where they interact with each other through the connective, conductive tissue on the board itself. There is no need for external wires, since those connections are made through the copper pathways on the board.

Such a process clearly eliminates the need for unwieldy wires, thereby reducing the need for a larger, more spacious box. Circuits can be made to be more compact, fitting in a fraction of the space they would take up on a breadboard. With the elimination of internal wires, connections can be made more secure, as well; since the boards themselves contain the conductive elements, there is no need to worry about frayed wires. A strong solder connection is all that is necessary to attach a component.

Printed Circuit Designs and the Need for Forethought

As you might imagine, the process of imprinting a full circuit design onto a PCB requires a great deal of planning and forethought. With wires and a breadboard, it is easy enough to reconfigure an entire circuit with relative ease. Achieving the same results on a board that is imprinted with conductive pathways is significantly more complicated, if not impossible.

Many designers will plan their circuits, then, with the invaluable assistance of a computer-aided design (CAD) program. CAD applications will allow a person to configure inordinately complex circuits and test them, all within the computer's virtual environment. This way, an engineer can know precisely how a given circuit will operate before spending time, money and effort on the creation of the actual PCB.

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