The Research for Quickly Measuring the Diameter and Roundness of Solder Balls Based on Machine Vision Technology

Abstract

Solder balls used in electronic packaging should have high dimensional and shape accuracy requirements to ensure the connection quality of solder balls during soldering. However, the existing solder ball detection methods were hard to measure the diameter and roundness in an integrated and fast manner. Therefore, a new method and device for measuring the diameter and roundness of solder balls was proposed based on machine vision technology, including detection device and software design. The experimental device could detect the parameters of at least 40 solder balls at a time. The solder ball image was preprocessed in the software system to improve the quality of the solder ball image, and then the Harris operator successfully detected the concave point on the bonded solder ball image and realized the solder ball separation based on the shortest path matching criterion. Compared with the scanning electron microscope (SEM) measurement value, the diameter and roundness of solder balls measured by the detection system were smaller than 3%.