Subpixel precision BGA chip localization method based on Lagrange interpolation

The vision-based industrial chip positioning method is very important for the application of surface mount technology. Because of the particularity of BGA package, its localization algorithm is suitable for image processing. In this paper, a complete set of subpixel positioning algorithm flow of BGA chip is proposed and a new smoothing method is introduced. When obtaining the subpixel coordinates, we use 8 directional templates to find the interpolation direction and derive the Lagrange interpolation formula to calculate the subpixel position, and then use the least square method to calculate the solder pad position and the chip rotation angle. Through experiments, the accuracy of our algorithm is better than that of traditional pixel-level detection methods.