Printed circuit boards provide mechanical support for electronic and electromechanical components. PCB fabrication involves a variety of steps. The first step is to prepare the computer-aided design of the desired circuit. This CAD includes information about details as well as their routine and interconnection. A variety of computer software is available in the market for this purpose. The CAD is converted to Gerber file format for distribution to the manufacturer. It is optimized in terms of time and cost by collecting smaller PCBs to a single printed board, as shown in the figure below.
The designed pattern of CAD in PCB fabrication is transferred to the copper sheet with the help of any of the following methods, such as photo engraving, silk screen printing, milling, or laser etching. The choice of method depends on the quantity of the order. Several layers are also decided when CAD is prepared in the PCB fabrication process. Apart from transferring the sketch to the copper layer, if the multi-layer board is used, then it is formed with the help of pressing and pressurizing of layers together.
After removing extra copper above the layers, drilling is done on the board to provide space for the insertion of components of the circuit. PCB fabrication involves different types of holes, such as blind vias, see-through holes, multi-layer holes, etc.
The different areas which don’t need soldering are masked with the solder mask generally available in green color. Other acts are also used in PCB fabrication. Identifications and legend are applied on the top of the solder mask, and it is called silk screen printing, as shown in the figure below.
PCB fabrication without components is sometimes called bare PCB and is usually tested for short and open connections and traces. After testing of fractions, electronic components are assembled on the board and soldered. A quality inspection is carried out as a final step of PCB fabrication before delivery to the customer.