Defect Classification using Pressure Change of Sleeve Soldering Machine

Abstract: The solder joint significantly affects the quality of the electronic equipment. Recent researches focus on the automatic inspection of solder joints to detect the fault with high accuracy. The sleeve soldering system is one of the soldering equipment. The system puts a heated ceramic sleeve over the through-hole of the print circuit board and melts the solder piece dropped into the sleeve. The system also feeds a certain amount of nitrogen gas into the sleeve continuously, and the gas goes out through the lower end of the sleeve. Pressure in the sleeve is changed by narrowing down or blocking the exit hole in each soldering process, such as the sleeve approaches to the print circuit board, drop off the solder piece, and solder melting. Here, the pressure at each process may differ between correct and incorrect soldering. In this paper, the authors classify the correct and incorrect soldering from the pressure change's features. The results of the experiment show that both correct and incorrect are classified with 98.3% accuracy.