What is a PCB (Printed Circuit Board)? - Another Teaching Moment | DigiKey

At their core, PCBs are multi-layer platforms that secure and interconnect electronic components to form functional circuits. The foundation of a PCB is typically made from FR-4 (flame-resistant, grade 4 fiberglass-reinforced epoxy), a non-conductive substrate chosen for its durability and fire-resistant properties. This core is then clad with a thin layer of copper using heat and adhesive in a pressing process. The copper layer's thickness is measured in ounces, with common variants being 1/2 ounce, 1 ounce, and 2 ounces. This copper layer is crucial as it can be etched to create a multitude of intricate conductive paths and connection points for electronic components. Beyond the core and copper layers, PCBs benefit from additional finish layers that enhance their functionality and durability. The bottom finish layer, known as solder mask or solder resist, is a thin coating of epoxy liquid that serves multiple purposes. Like masking tape, it 'masks off' areas where solder is not desired, protecting copper traces from oxidation and preventing accidental short circuits. This layer also plays a crucial role in the soldering process by preventing solder bridges between exposed pads. The topmost layer of a single-sided PCB is dedicated to providing essential information. This layer typically includes details about the board itself, its components and their values, and any other key information the designer wishes to convey. This informational layer aids in assembly, troubleshooting, and future modifications of the PCB. The complexity and versatility of PCBs have made them indispensable in the rapid evolution of electronic devices across various industries. From simple calculators to advanced smartphones and spacecraft, PCBs enable the compact, efficient, and reliable electronic circuits that power our modern world. As technology continues to advance, the role of PCBs in electronics is likely to grow, with ongoing innovations in materials, design techniques, and manufacturing processes further expanding their capabilities and applications.