The Research And Development Of Laser-Soldering System Based On BGA Chips

With the increasing demands on high pin densities, growing functions, and decreasing size in electronic products, the traditional packaging techniques could not meet such requirements well. Meanwhile, the introduction and wide application of SMT technology accelerates the developments of flip-chip packaging techniques. With the characters of more I/Os and smaller dimension, therefore, Ball Grid Array (BGA) chips gradually becomes the leading method for IC packaging. This paper describes the design and construction of an experimental prototype laser-soldering system workstation based on BGA chips. The key modules of this workstation are machine vision alignment system, motion positioning control system, and laser control system.Machine vision is used to align the target part to be soldered on chip. Since a prototype machine vision alignment system was accomplished before, this paper is focusing on how to extract its functions and re-package them from a text-based programming platform for the graphic platform-LabVIEW. Further more, according to the requirements of whole equipment, some improvements are implemented.The motion positioning control system is responsible for locating the target part onto the work position precisely. Based on the analysis of location error, relying on the machine vision, this paper proposes a calibration and compensation approach to rectify the positioning errors. Subsequent experiments verified the validity of the calibration and the system finally satisfied the manufacturer's specification on solder bumps with diameter of 0.3 mm.The laser control system is in the charge of controlling reflow power, current, and duration time. This paper introduced a graphic programming platform to integrate whole modules motioned above into complete...