How a Printed Circuit Board Is Made
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Almost every modern electronic device uses a printed circuit board, or a PCB, to mount the electronic components it needs in order to operate. The position of these components relative to one another determines how well the device will operate, so PCB design is critical. A good PCB manufacturer tailors PCB layout to fit a particular industry’s needs. The mother board that a personal computer relies upon for optimal performance is configured differently from the audio amplifier board used in sound production.
PCBs are typically made from thin layers of copper foil fixed into place with epoxy resin. The copper layers are then etched with the circuit design. The three most popular methods of etching a printed circuit board are silk-screen printing, photoengraving and a process called milling that involves the use of specialized, computer-driven mechanical equipment. The topmost layer of the PCB is often coated with a fusible metal alloy that is green in color.
Once the board is constructed, the PCB manufacturer attaches the necessary electronic components to create a printed circuit assembly. Electronic components can be mounted in small depressions or holes in the printed circuit board, or on upraised pads on the PCB surface. Metal solder is used to fix the electronic components into place.
Quality assurance is an important part of the PCB manufacturing process. A PCB manufacturer determines that a board will work by visually inspecting the board while the power is off, or by using an automated device to inspect it. Power-off testing continues by using a technique called analog signature analysis, which applies a low AC current across combinations of PCB points. With the power on, an in-circuit test is performed, checking for shorts and also measuring such properties as resistance and capacitance. Finally, a functionality test will be performed to make sure the printed circuit board does what it was designed to do.