There are a few different approaches to the PCBA process, which vary mostly based on the tools and technologies used to complete the assembly. Although there is a lot of room for variation in this process, it is still possible to outline some steps that typically occur throughout.
The following are some of the most important steps that generally get included in the PCBA process:
1. Solder paste
In a traditional PCBA process, the application of solder paste to the PCB is usually the first step. It is very important to accurately place the correct amount of paste onto each of the pads that require soldering. Although solder paste does not typically need to be applied with THT, it is required for SMT.
2. Component placement
The second step in the traditional PCBA process involves placing the components on the board, which can be done either manually or with the assistance of machinery. If a THT approach is taken, incredibly precise hand placements are required. For SMT, though, robotic systems are utilized for component placement, which is just as precise but faster.
3. Reflow
Traditionally, reflow is the next step, which involves the solder being melted and resolidified. As the board and its components all move through an oven, the solder is heated and liquefied.
Then, connections are formed before it is moved into a cooler, where the solder cools and hardens again. In THT, reflow is not required, although the board must undergo a thorough inspection to ensure component placement accuracy.
4. Through-hole part insertion
Traditionally, through-hole insertion is done manually at the next stage once the board has undergone a visual inspection. Soldering may also be done manually at this stage, although a wave-soldering method may be used for certain processes as well, such as the THT approach. This involves the entire board moving through liquid solder and then through coolers to solidify the solder.
5. Final inspection and cleaning
In the traditional PCBA process, the last step involves a final inspection of the board, the solder points, and the components to ensure that no issues are present. Following this inspection, the board, solder points, and components should also be cleaned to remove any debris or excess solder. After this, the assembled PCBs may be packaged for distribution or further manufacturing.
