The main difference between SPI and AOI buffer in the SMT process is: SMT buffer is the quality inspection of solder printing, through the inspection data to debug, verify and control the solder paste printing process; while AOI buffer is divided into two types: before and after the furnace. The former inspects the device placement and the stability of the placement before the furnace, while the latter inspects the solder joints and inspects the welding quality after the furnace.

SPI is for the quality inspection of solder printing and the debugging, verification and control of the printing process. Its basic functions:

1. Discover the shortcomings of printing quality in time. SMT buffer can intuitively tell users which solder pastes are printed well and which ones are bad, and provide prompts on the types of defects.

2. Through a series of solder joint inspection, find the trend of quality change. SMT buffer detects the quality trend through a series of solder paste inspections, and finds out the potential factors causing this trend before the quality does not exceed the range, such as the control parameters of the printing machine, human factors, and solder paste change factors. Then make timely adjustments to control the continued spread of the trend.

AOI buffers have various mounting and soldering defects in the SMT production process, such as missing parts, tombstones, offset, extreme inversion, empty soldering, short circuits, wrong parts and other defects. Nowadays, electronic components are becoming more and more. Small, relying on manual visual inspection, slow speed and low efficiency. AOI checks for poor placement and soldering. It uses image contrast. Under different lights, the bad will show different pictures, passing good pictures and bad pictures By comparison, defective points can be found and repairs can be carried out with fast speed and high efficiency.