PCBA PRACTICE OVERVIEW
The various stages in the PCB assembly process including adding solder paste to the board, pick and place of the components, soldering, inspection and test. All these processes are required, and need to be monitored to ensure that product of the highest quality is produced. The PCB assembly process described below assumes that surface mount components are being used as virtually all PCB assembly these days uses surface mount technology.
Solder paste: The solder paste is a paste of small grains of solder mixed with flux. This can be deposited into place in a process that is very similar to some printing processes. Using the solder screen, placed directly onto the board and registered in the correct position , a runner is moved across the screen squeezing a small mount of solder paste through the holes in the screen and onto the board. As the solder screen has been generated from the printed circuit board files, it has holes on the positions of the solder pads, and in this way solder is deposited only on the solder pads.
Pick and place: During this part of the assembly process, the board with the added solder paste is then passed into the pick and place process. Here a machine loaded with reels of components picks the components from the reels or other dispensers and places them onto the correct position on the board.
In some assembly processes, the pick and place machines add small dots of glue to secure the components to the board. However this is normally done only if the board is to be wave soldered. The disadvantage of the process is that any repair is made far more difficult by the presence of the glue, although some glues are designed to degrade during the soldering process.
Soldering: Once the components have been added to the board, the next stage of the assembly, production process is to pass it through the soldering machine. Although some boards may be passed through a wave soldering machine, this process is not widely used for surface mount components these days.
Inspection: When the boards have been passed through the soldering process they are often inspected. Manual inspection is not an option for surface mount boards employing a hundred or more components.
Test: It is necessary to test electronic products before they leave the factory. There are several ways in which they may be tested. To know others methods , consult to our Engineering department.
The PCB assembly process for the manufacture of loaded printed circuit boards has been considerably simplified in this overview. In view of the number of components and solder joints in today’s products, and the very high demands placed on quality, the operation of this process is critical to the success of the products that are manufactured.
