The printed circuit board (PCB) is the core of every electronic device we connect today. These PCBs basically interconnect electronic components by establishing conductive paths through copper pads and connecting wires. Therefore, the mixed technology PCB assembly process has become one of the most interesting concepts in electronics.
Most PCBs use through-hole technology assembly (THT), surface mount technology assembly (SMT) and mixed technology PCBA assembly processes.
Traditional PCB assembly process
1. Application of solder paste
2. Component placement
5. Insert through-hole parts
5. Final inspection and cleaning
Through-Hole Technology Conference (THT):
1. Component placement
During this process, the components are installed manually by experienced engineers. The installation process of manually picking and placing components requires maximum precision and speed to ensure component placement. Engineers should follow THT standards and regulations to achieve the best functionality.
2. Inspection and component calibration
The PCB board matches the design transportation frame to ensure the precise placement of the components. If any misallocation of components is found, it will only be corrected at that time. Correction is easier before welding, so the position of the component is corrected at this stage.
3. Wave soldering
In THT, wave soldering is performed to cure the solder paste and keep the component intact at its specific location. In wave soldering, the component-mounted PCB board moves over the slowly moving liquid solder, and the liquid solder is heated at temperatures above 500°F. It is then exposed to a cooler to solidify the connection.
Surface Mount Technology Assembly (SMT):
The PCBA steps followed in SMT assembly are as follows:
1. Application/printing of solder paste
Refer to the design template and apply the solder paste to the board through a solder paste printer. This ensures that the solder paste is printed in a satisfactory quantity at a specific location.
2. Component placement
The placement of components in SMT components is automatic. The circuit board is sent from the printer to the component mounting rack, where the components are picked up and placed by an automatic mechanical pick-and-place mechanism. Compared with manual processes, this technology saves time and also ensures the accuracy of specific component positions.
3. Reflow soldering
After the components are installed, the PCB is placed in a furnace, and the solder paste is melted and deposited around the components. The PCB passes through the cooler to fix the component in this position.
Surface mount technology (SMT) is more efficient in the complex PCB assembly process.
Due to the increasing complexity of electronic equipment and PCB design, mixed assembly types are also used in the industry. That is, the mixed technology PCB assembly process is a combination of THT and SMT.