PCB Board Fabrication Is Used in Industry
PCBs are critical in a number of industries. The automotive industry depends on them for components like engine control units (ECUs), which manage complex engine functions such as ignition timing and fuel injection. They also help provide the foundation for advanced driver-assistance systems and infotainment systems in automobiles. The renewable energy boom has created an increased demand for high-quality PCBs that can be used in devices such as solar power inverters and wind turbines, which manage current changes from the sun and blade pitch respectively. Consumer electronics, too, rely on quality PCBs for features such as cellular radios, Wi-Fi and GPS that are crucial to our daily lives.
The pcb board fabrication process begins with a base material, which is usually a dielectric composite material, such as epoxy resin and glass fibers. A layer of copper foil or a coating is then added over this, and a film with a printed image of the circuit’s conductive traces and component mounting locations is placed on top. The photo-reactive chemicals in the film harden with exposure to light and cover the board, creating a photo-resist. The circuit images on the photo-resist are matched up with a preloaded CAD/CAM design file to create the desired PCB layout.
A machine then drills holes for the traces and leaded components by using an X-ray system to locate the targets, which are called registration holes. The drilled holes, which can be as small as one micron, are then filled with solder, either through-hole or surface mount technology, by a wave-soldering machine. The resulting raised ends of the copper, known as burrs, are then removed with a deburring tool.
How PCB Board Fabrication Is Used in Industry
After the traces are completed, they are etched. Several chemicals may be used for this, but the most common is ferric chloride, which removes areas of the copper that are not needed, leaving bare circuitry. In order to avoid damage, the solution must be diluted correctly and not left in for too long, so proper mixing and timing are essential.
The remaining copper is then plated with tin, which provides a barrier against corrosion and serves as an electrical conductor for the traces. The board is then inspected and repaired where necessary. The finished product is then packaged and delivered to the customer.
The simplest PCBs feature a single layer of substrate and a thin copper coating, which are then etched to create the circuit patterns. These are cost-effective and find utility in straightforward electronic devices like calculators and radios. More complicated boards elevate complexity by adding conductive metal layers on both sides of the substrate, which are etched to create a more intricate circuitry pattern.
These double-sided boards, which can include multiple layers of copper and a variety of connections between them, find use in more advanced devices such as amplifiers and computer motherboards. In order to be functional, both sides of the board must be finished properly. A legend, or silk screen, is added, containing information such as component designators and switch settings. This information is useful in assembling, testing and servicing the device once it has been assembled.