Printed Circuit Board assembly (PCB assembly) is a crucial process in the electronics manufacturing industry, involving the integration of electronic components onto a PCB to create a functional electronic device. The process begins with the design and fabrication of the PCB itself, typically made from a non-conductive substrate such as fiberglass, with conductive pathways etched from copper sheets. The assembly process includes several key steps. Firstly, solder paste is applied to the PCB's surface at the locations where components will be placed, usually using a stencil and a squeegee for precise application. Following this, the electronic components, including resistors, capacitors, diodes, and integrated circuits, are placed onto the PCB. This placement can be done manually or, more commonly, using automated pick-and-place machines that ensure high accuracy and efficiency. Once all components are placed, the board undergoes soldering to secure the components. There are two primary methods: reflow soldering, used for surface mount technology (SMT) components, and wave soldering for through-hole components. Reflow soldering involves heating the board to melt the solder paste and create a solid bond, while wave soldering involves passing the board over a wave of molten solder. After soldering, the assembly is inspected for defects, which can include manual inspection, automated optical inspection (AOI), and X-ray inspection, depending on the complexity and requirements of the assembly. Any defects identified are typically corrected through rework. Finally, the assembled PCB may undergo functional testing to ensure it operates as intended.