Dating back to the early days of electronics, to the times when it was vacuum tubes that ruled out in the industry, all components making up electronic devices were connected through soldering them together or to tube sockets and terminal strips. These days, however, PCBs manufactured by a printed circuit board manufacturer are now being used to connect components much cheaper and simpler.
PCBs are very thin boards that have been made from insulating materials. These insulating materials are known to have metal coated surfaces, either at the top or the bottom. Metals will be etched with the use of acid so there will be pathways for electric current to travel through the components which will be surface mounted on boards by the process of soldering.
The invention as well as the development of the PCB has come so benefit to the world of electronics. It is one of those that have prompted circuits used in electronics to come in smaller sizes and more compact. It also enabled containment using convenient or rugged boards. A circuit board comes with holes. These are what allow the soldering or insertion of components such as capacitors and resistors through automation.
PCBs are becoming more and more common these days. Almost all electronic appliances operating in homes have these very distinct boards. They often come in many different types. Among the most common appliances that contain these are answering machines, digital clocks, stereos, printers, cellphones, microwave ovens...