Effect of Laser Fluctuations in Automated Solder Joint Inspection

摘要

A study was performed to assess the significance of potential fluctuations inpower output of the heating laser in automated laser inspection systems. So that the effect of variations in power output could be determined, heat-transfer analysis was conducted on a simplified model of a solder connection using finite-element methods. The study indicates that 10-percent modulation about some mean power input produces the same frequency of modulation as the input, but slightly damped amplitude, in the infrared emissions measured during the heat-up phase; the error is negligible after the laser is terminated. The study also indicates that a 10-percent increase or decrease in average power input produces an error in measured infrared emissions of approximately 11 percent throughout the process. The latter results were corroborated by a mathematical model. Keywords: Thermal signature, Solder joint inspection, Lasers. (js)