Electronics PCBs
A printed circuit board (PCB) is a sandwich-like structure that consists of an insulator, such as fiberglass or polymer, and conductive layers, most commonly copper. The conductive layers are etched in a specific pattern to create the circuit. This is what gives the PCB its functionality, as it allows electronic components to be attached to different spots on the board.
The process of making a electronics pcb requires specialized equipment and a high degree of skill and knowledge. The board must be made in an extremely clean environment to ensure that there are no contaminants that could interfere with the electrical connections. It must also be carefully inspected for flaws to ensure that the circuitry is correct. Printed circuit boards can be used for a wide variety of purposes, including in consumer electronics like phones and tablets, industrial control systems, and medical devices.
Before the manufacturing process can begin, a designer must prepare the layout of the circuit pattern on a computer-aided design system. This is done using a special software program, such as KiCad, and is saved in a file format called Gerber. The files contain a 3D model of the circuit layout, and also include the specifications for the copper foil, solder mask, and silkscreen layer.
How Are Electronics PCBs Made?
Once the design is complete, it must be sent to a manufacturer to be turned into a physical product. The manufacturer begins by making the substrate, which is typically woven glass fiber impregnated with epoxy resin. This is then rolled into the desired thickness and semi-cured in an oven before being cut into panels. The panels are then layered with adhesive copper foil in an alternating pattern. The copper foil is then pressed at high temperatures to bond it to the substrate. The next step is to add the solder mask, which is an insulating layer that covers the conductive copper. The silkscreen layer is added last, which provides a label for each component on the circuit board, as well as any additional information needed for assembly and maintenance.
After the insulating layer is applied, the copper traces are cleaned with a solvent that removes any residue. This is followed by a chemical treatment that exposes the copper to be electroplated with gold, which provides an electrically conducting surface for connections. After the copper is plated, another solvent is used to wash away the hardened resist that was protecting the desired copper areas of the circuit board. The remaining copper is then etched with acid, which dissolves the unwanted copper. This process is repeated for any other etching steps that may be necessary.
The next step is to apply the solder, which is a thin paste composed of metal and flux. The solder is then placed onto the circuit board and melted to make an electrical connection. The circuit is tested for continuity and isolation before being sent to a final inspection area where any visual or electrical flaws can be detected. The boards are then packaged for shipping and distribution.