Tolerance analysis of placement distributions in tethered micro-electro-mechanical systems components

This work presents a framework of tolerance analysis of microparts in microassembly. Tolerance analysis at the micro scale has not been investigated so far even though tolerance analysis at the macro scale has extensively been investigated to improve an assembly yield. It is important to know the positional uncertainties and statistical distribution of parts before and after untethering to improve assembly yield. Positional misalignments of microparts are extracted from raw CCD images and the statistical distribution of parts variances are computed using clustering and transformation of Gaussian distribution. The distributions are not pure Gaussian in nature as might be expected. There are several location peaks found, usually centered at the fabrication location, and at the hard-stop locators.