A sub-millimeter packaged microsystem includes a microsystem located in a sealed cavity defined between first and second portions of a micropackage. One or both micropackage portions can be fabricated from a metal suitable for use in a harsh environment, such as an oil well environment. The microsystem includes electronic components and can be configured to communicate with external components through a wall of the micropackage by wireless communication or by conductive feedthroughs. Pluralities of microsystems, first micropackage portions, and/or second micropackage portions are simultaneously placed during a batch assembly process. The assembly process may include micro-crimping the first and second micropackaging portions together without the need for bonding materials and related process steps.