3-dimensional solder paste inspection using Structured Light techniques

Abstract

Re-modelling of three-dimensional solder paste constructed from optical profilometry has gathered ever-increasing attention in different inspection and process control sectors of the electronics Printed Circuit Board manufacturing industry. It has been shown that 50% to 80% of the solder defects encountered are usually a direct consequence of variations in the quality of board printing. Since the amount and shape of solder paste on pad affects primarily the quality of joints, a highly accurate control system is necessary to correct process drift before the value- adding process in the form of integrated circuits and microprocessor chips has been added to the board. The process control systems commercially available today are either low-cost equipment which operate on a statistical basis, and have certain degree of limitations on the inspection of the system, or are based on laser scan technologies which are exceptionally expensive. In the existing market for solder paste inspection equipment, systems must be capable of achieving inspection rates in real-time, delivering area, height, and volume of solder paste deposits. In order to attain zero defects, every paste deposit on the board should be monitored. The aim of this work is to investigate the feasibility of a low cost, non-contact, high-speed, online system for the inspection of low attitude objects such as Surface Mount Technology (SMT) component solder-joints.