What Is PCB Assembly?

PCB assembly is the process of assembling printed circuit boards. It consists of many steps that must be performed correctly. Among them is checking the design file, which must be detailed enough for a PCB assembly company to perform a thorough check for errors. A manufacturability check looks for features that may be redundant or missing, which will negatively impact the final project. Also, it is important to check for component spacing, which is critical as too little space can cause shorts or malfunctions.

During the PCB assembly process, solder paste is applied to the PCB, similar to how a screen printer applies ink to a shirt. The assemblers will then apply solder paste to a thin stainless steel stencil that will only cover certain parts of the board. After the paste is applied to the board, components will be placed on the board at specific locations. This allows for a more accurate and precise PCB assembly.

After the design process is complete, the board is assembled. PCB assembly involves placing the required electronic components on the board. Traces, which are copper lines on a bare board, run signals between the various features. Ultimately, the board will function in the way it was designed to. PCB assembly involves several manual and automated steps. The manufacturer can choose between mechanical and manual assembly for each step. The latter is more accurate and requires minimal skill.

Another important step during PCB assembly is the placement of surface-mount components. The proper placement of these components is essential to ensure the final result of the project. For this purpose, the assembler should select the right size of the package. Smaller packages require the assembler to pay attention to component placement. A mistake on this step can lead to uneven heat generation during the soldering process, and it can even lead to the component sticking to one side of the PCB. Moreover, improperly aligned components may also affect passive SMD components. The width and magnitude of the tracks connected to the pads can cause the components to stick to only one side of the board.

Another PCB assembly method is box-build assembly. Usually, the PCB is a box-like enclosure, complete with wires and other components. Box-build assembly, on the other hand, refers to the complete assembly of a customer's finished product. The term "box" is also used for PCB assembly in a cabinet with many wires. In a box-built PCB assembly, the finished product is fully integrated with an electromechanical system.

The alternating sandwich of materials on a multilayer PCB is the most common type. The inner copper layer is etched and plated through before the adjacent layers are laminated. The insulating substrate for multilayer PCBs is typically FR-4 glass epoxy. In addition, cotton paper is impregnated with phenolic resin and is usually tan in color. This process requires careful inspection of the resulting board.