What Is The Difference Between AOI And SPI In SMT Process

AOI (Automatic Optical Inspection) and SPI (Solder Paste Inspection) are two crucial inspection technologies in SMT processing, and they both play an irreplaceable role in ensuring product quality, but their respective responsibilities and inspection stages are different.

• AOI Technology

AOI, i.e. Automatic Optical Inspection, is a technology based on optical principles for automatic inspection of components and solder joints in SMT processing. It captures images of circuit boards with the help of high-resolution cameras and analyzes these images in depth using image processing algorithms.

In this way, AOI is able to accurately detect the presence of defects in solder joints and components such as missing parts, wrong parts, offsets, standing monuments, bridging, and false soldering. These defects, if not detected and handled in time, will pose a serious threat to the performance and stability of the board.

Therefore, the AOI technology in the SMT processing process acts as a quality guardian, providing a strong guarantee for the quality control of products before they leave the factory.

• SPI Technology

In the SMT placement process, solder paste serves as the connecting adhesive between the electronic components and the PCB substrate, and its quality and coating accuracy are critical.SPI, or solder paste inspection, is an automated optical inspection technology used to assess the quality and positional accuracy of solder paste.

Equipped with a high-resolution camera, light source and image processing software, it is capable of accurately detecting solder paste thickness, shape, positional offsets and possible defects by capturing and analyzing images of solder paste spots.

The introduction of SPI technology enables manufacturers to identify solder paste-related problems early and take corrective action accordingly, thus ensuring solder quality and product reliability.

• What is the difference between AOI and SPI?

SPI focuses on solder print quality inspection and aims to debug, validate and control the solder paste printing process through inspection data. It focuses on the printing quality of solder paste in order to detect and correct any problems that may occur during the printing process.

AOI, on the other hand, focuses more on device placement and solder quality inspection. Divided into two kinds of pre-furnace and post-furnace inspection: pre-furnace AOI mainly detects the stability and accuracy of device placement; post-furnace AOI is responsible for checking the quality of soldering to ensure the quality and reliability of the solder joints.

AOI and SPI in the SMT process each plays an indispensable role, they are through the automatic optical inspection technology for SMT processing provides an efficient and accurate means of quality control, thus ensuring the performance and reliability of the final product. For the pursuit of high quality and efficiency of the modern electronics manufacturing industry, these two technologies is undoubtedly an indispensable assistant.