Yield loss improvement based real time automated machine vision inspection system (MVIS) application for thin film solar cell laser micromachining

Laser scribing plays an important role in defining the solar cell area of thin film photovoltaic (PV) solar modules. The scribing lines produced by high-repetition-rate laser tools or laser micromachining, define the dimensions of the active area that separate the modules into smaller individual power cells. Both resolution and precision are important in laser micromachining applications during mass production of PV solar modules. It is critical to maintain high quality scribes and minimize scribing defects. However, like many others laser machines, there is an issue in determining scribing failure or defects in solar modules. A conventional inspection system using area-array cameras to snapshot small sections of the solar module is the only available method that can accurately detect any cut-quality defects. Nonetheless, this system is unable to tolerate a fast throughput environment that requires real time monitoring which is crucial to avoid high fall out and prevent yield loss for finished products. Hence, this research was written to investigate yield loss improvement through the implementation of imaging technique of machine vision. Machine vision inspection system are builds and design in a fully integrated and automated manner with the continuous flow of the PV cell manufacturing process. It covers all laser cuts on the surface of the solar modules compared with small section samplings from manual inspection and time consuming area-array camera analysis. This automated inspection system is expected to reduce manufacturing cost more than $17,000 per month and improve existing quality control over defect product. It is also estimated to reduce 70% of production yield loss from the existing laser micromachining process.