Master of Science in Mechanical Engineering (MSME)
One of the major difficulties faced by MEMS researchers today is the lack of data regarding properties of electroplated metals or alloys at micro-levels as those produced by the LIGA and LIGA related process. These mechanical properties are not well known and they cannot be extrapolated from macro-scale data without experimental verification. This lack of technical information about microscale physical properties has affected the consistency and reliability of batch-fabricated components and leads to very low rates of successful fabrication. Therefore, this material issue is of vital importance to the development of LIGA technology and to its industrial applications. This thesis focuses on the development of a new capability based on design, fabrication, and testing of groups of UV-LIGA fabricated nickel microspecimens for the evaluation of fracture strength. The design of the test specimens involved determining the appropriate dimensions and configuration based on a set of criteria dictated by the objectives of the project. Likewise, the development of the specimens required some experimentation with different microfabrication techniques, and combinations thereof, to generate a final fabrication sequence that would produce suitable freestanding, wafer-bound specimens. The devised testing mechanism demonstrated compatibility with the fabricated samples and capability of performing the desired experimentation by generating resistance-to-fracture values of the nickel specimens. The average fracture strength value obtained, expressed with a 95% confidence interval, was 315 ± 54 MPa. Preliminary testing results proved that further data acquisition, especially involving tensile specimen testing, and material analysis is needed to fully understand the implications of the information obtained. The products of this new microspecimen testing approach can be extended for use with other microfabricated metals and metal alloys, particularly on a more qualitative, comparative basis.
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Oropeza, Catherine, "A new approach to evaluate fracture strength of UV-LIGA fabricated nickel specimens" (2002). LSU Master's Theses. 2669.