In the manufacturing process of PCB assembly, we still have a lot of work to do. From start to finish, there are many processes involving varying degrees of mechanical, automation, and manual intervention. So every step needs to be carefully checked. Finally, the circuit board assembly can be completed.

PCB assembly inspection is mainly to verify the correct placement and soldering of electronic components on the PCB.

Automated Solder Paste Inspection (SPI): Work from the same CAD file used to make the solder paste template. The SPI system uses a laser scanner and high-resolution image processing to check the shape and volume of solder paste and alignment pads on the board. The amount of solder paste on the pad may vary according to the components to be attached, and the shape of the solder paste may be different from the shape of the pad used to reduce solder gaps or bridges.

First piece manual inspection: After the components are installed on the first circuit board, the inspector will check all the components according to the bill of materials before reflow soldering the circuit board. The inspector will confirm that the part matches the bill of materials and that its position and orientation are correct.

If there is no problem, the circuit board will establish a set of images through the automatic optical inspection system, and other manufactured circuit boards will be automatically compared.

Automatic Optical Inspection (AOI): The first circuit board will be used as the standard, and the AOI system will compare the correct placement of the components and all visible solder joints in the subsequent circuit boards. The system uses a combination of illumination wavelengths and high-resolution cameras to check component markings, such as polarity indicators and resistive ribbons. It will detect open solder joints, insufficient solder, solder bridges and misaligned parts.

The system can also be adjusted according to the needs of the processed circuit board. False alarms can be eliminated, and some anomalies can become more sensitive to alert operators in critical areas. The AOI system can also be programmed to accept replacement parts.