Primary Applications of Printed Circuit Board Assembly
PCBs are used in a wide variety of electronic and electromechanical devices to perform various functions. The assembly of a printed circuit board is an integral part of its overall function. The bare PCB is populated or “stuffed” with component parts, which transforms it into a functioning printed circuit board assembly (PCA). The components are either inserted using through-hole technology or surface-mount technology (SMT). Both types of assemblies serve different purposes and have unique advantages.
The first step of a printed circuit board assembly is applying solder paste to the surfaces where components will be placed. This is done through a stencil. The PCB then undergoes a heating process to melt the paste, which forms a rigid bond when it cools. Next, the board is sent on a conveyor belt to robotic pick and place equipment that adds surface mount components. The machines are programmed with files that contain the relevant coordinates for each component. The placement is fast and accurate. In some cases, a small amount of adhesive is applied to certain areas of the PCB in order to hold the parts in place.
After all of the components have been positioned, the PCB is placed in a heating chamber to liquefy the solder, which will then fasten all of the pieces into place. Once this is complete, the boards are cleaned using an automated washing tool that uses deionized water and a cleaning chemistry to remove any residual flux residues, stains, oil, and fingerprints.
What Are the Primary Applications of Printed Circuit Board Assembly?
In addition to the above steps, there are some additional considerations when handling a PCB during assembly. Because the traces are very fine, a static charge on the surface of the PCB can affect its functionality. To prevent this, the board is often wrapped in an antistatic bag. Additionally, it is important for the operators to be grounded while working with the PCB, as static charges can be transmitted through the board and damage or destroy components.
The primary applications of a printed circuit board assembly include consumer electronics, industrial equipment, and automotive electrical systems. Printed circuit board assembly is also used in aerospace devices, communications equipment, and other high-technology applications.
Printed circuit boards are made of dielectric composite materials, typically epoxy resin with a reinforcement material such as woven or non-woven glass fibers, cotton paper impregnated with phenolic resin, or a fiberglass-based laminate. The most common insulating substrate material is called FR-4 and contains copper on both sides of the board stock.
Depending on the complexity of the board, it may be necessary to design a schematic for the circuit. This design stage includes front-end engineering, where ECAD software translates simple circuit diagrams into electronic drawings and identifies the functional connections between components. It also includes laminate materials selection and a PCB stack-up design, which determines the locations of plane layers, signal layers, and routing channels. It also specifies the thickness of the various layers of the board.