PCB Assembly (PCB Assembly) is the process of installing electronic components onto a printed circuit board (PCB) as designed to form a complete circuit. The process usually includes the following key steps:

1. SMT (Surface Mount Technology) Assembly:

   - Stencil Printing: uses a stencil to accurately print solder paste onto pads on the PCB.

   - Component Placement: Automated SMT Placement Machine (SMT Placement Machine) places Surface Mounted Components (SMDs) to the specified locations on the PCB according to the BOM and PCB design.

   - Reflow Soldering: The PCB board passes through the reflow oven and the solder paste melts, fixing the SMD components on the PCB board.

2. THT (Through-Hole Technology) Assembly:

   - Drilling: Holes are drilled in the PCB for inserting pins.

   - Plug-in: Manual or automatic plug-in machine inserts components with pins into the holes on the PCB.

   - Wave Soldering: The PCB board passes through the wave soldering machine and the solder covers the pins and pads to form a solder joint.

3. Post-processing:

   - Cleaning: Remove flux residue from the PCB board.

   - Inspection: Perform visual inspection and automatic optical inspection (AOI) on the assembled PCB.

   - Testing: Perform functional, electrical and performance tests to ensure that the PCBA meets the design requirements.

4. Final inspection and packaging:

   - Quality Control: Conduct final inspection to ensure that all components are installed correctly without short-circuit, misalignment, etc.

   - Packaging: Properly package qualified PCBAs for shipment.

The quality and efficiency of PCB assembly directly affects the performance and reliability of the final product. Therefore, quality control during the assembly process is very important. Modern PCB assembly factories usually use automated equipment and advanced testing technology to improve production efficiency and product quality.