A printed circuit board, or PCB, is a self-sufficient unit of interlink electronic components like capacitors, resistors or ICs. It is also available in devices ranging from common house hold electronic devices, or pagers. also Radios, radar and computer systems also contain PCB.
Vacuum tubes were king in older times of electronics; electronic devices contain components that were interlink by soldering them either to each other to terminal strips and tube sockets. Now day’s printed circuit boards have replaced all of them because of their reduced size and cheaper prices. Today, just about each and every electronic appliance in your home contains a printed circuit board of some type. Major types are computers, laptops, printers, mobile phones, TV, washing machines, refrigerators, musical instrument or coffee makers. Some other types are digital clocks, microwave ovens, telephone answering machines.
Printed circuit boards (PCBs) are thin boards made from an insulating material, with a metal coated surface, sometimes on both the top and bottom. Metal with acid is use for making etches to create pathways for electricity to travel among various components. Such components are mount on surface on the board with solder.
Printed circuit board assembly consists of multiple step process. After the completion of printed circuit board (PCB) , electronic components must attach to form a functional printed circuit assembly. These components are can attach either by surface mount technology (SMT) or through hole technology. In surface-mount (SMT – surface mount technology) construction, the components gets place on pads or lands. On the outer surfaces of the PCB and in through-hole construction, component leads are insert in holes. Component leads are attach electrically and mechanically to the board with a molten metal solder in both types of construction.
How to Attach Components to PCB
Different soldering techniques are preferable to attach components to PCB. SMT placement machines or reflow ovens are use for high volume productions . Skilled technicians complete the small prototype by hands under a microscope ,using tweezers and a fine tip soldering iron.
In test procedure, the assembled printed circuit boards are placed into a fixture that brings electrical power to the boards to make them live functioning boards.
Environmental stress system (ESS) chamber is use to place active boards that will cycle between high and low temperature. It regimes for a number of cycles to determine if these stresses will initiate failures in the assembled boards. So, Rework is important if board fails the test and technicians may be solder and replace failed components.