PCB assembly, a.k.a PCB fabrication, is a very complicated and intricate set of procedures that must be followed intently to manufacture a PCB that sticks to the functional specs set by the designer. This is a simple guide to the multilayer PCB assembly procedures, considering most PCBs created today have more than one layer. A bunch of PCB companies will ship designs overseas to be fabricated, while companies like Advanced Circuits have their manufacturing facilities in the great State of Colorado. For more printed circuit board information, click here.
Before the components are placed onto the printed circuit board, solder paste needs to be added to the areas of the board on which these components will be attached. These areas are marked with what are called component pads, and the paste, a combination of solder and flux, is applied to these pads, lightly coating them. This is accomplished through the use of a solder screen, which is generated from the PCB files sent to the manufacturer. In this step, solder screens are set on the board and the solder paste is pushed through the holes in the screen which will leave paste only where components will reside.
After that, the necessary components are pulled from a dispenser by a Pick and Place device and placed in the correct spots. The solder paste will hold the components to the board for now. Click here to learn more about printed circuit boards.
Once all components and the traces connecting them are in place, the PCB is "cooked" to make the connections permanent. It is common for manufacturers to use a reflow oven for this step. This machine heats the board to a temperature at which the soldered connections will melt into place, but the electrical components on the board will not be damaged. Multilayer and single layer circuit boards both follow this process. After the board cools for the necessary amount of time, it can then be inspected for quality control.
The complexity of a board or design determines what inspection is done. Larger, multilayer boards that have many components are usually subjected to an automatic inspection process that will check the board and its components against the original design. Solidity of the joints is another thing that these machines will check. Click here for more printed circuit board information.
Though the PCB assembly process is complete, the board must then be tested for functionality before it is sent to the consumer. The final inspection is dependent on the size of the design and the PCB layout.