The broader impact of this Small Business Innovation Research (SBIR) Phase I project is to enable manufacturers of solar cell assemblies to conduct quality control in real time. potentially reducing the cost of the solar cell modules and increasing production by an estimated 26%. Prospective customers of the envisioned technology are firms that make the assemblies (known as "strings"), and specifically producers of cell stringer tools. The system will have other renewable market applications, such as testing cracks on incoming silicon wafers prior to vacuum deposition of thin layers for back-side solar cells. The production-grade systems at the initial commercialization step will be made domestically, creating new jobs. In Phase I, Ultrasonic Technologies will team with a US-based module producer to integrate and validate the prototype in a commercial stringer and production environment. The project will be supported by two university research teams which provide education and training of graduate students in a high-tech production facility. The proposed project will demonstrate a multi-head Activation Station (AS) system, using controllable mechanical stress applied to the cell string through a specially designed multi-head vacuum chuck. The string stressing is followed by fast measurements of the responding deflection of the cell caused by vacuum loading. This deflection provides a sensitive means to assess the cell's mechanical integrity and to exhibit any hidden invisible cracks. The cell deflection also provides real-time control for how tight the technological parameters are of the stringing processes, e.g., annealing temperature, soldering thickness and soldering quality. A new AS method for rapid in-line crack detection in strings will adhere to a throughput rate of 4,200 cells per hour or a cycle time of 0.85 seconds per cell in modern production stringers. In parallel, the vacuum chuck design will be optimized to assure a high level of crack coverage which will be quantified through experimentation. Finite Element Analyses model will support the experimental data of crack inspection accuracy and sensitivity of the AS technology. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
