Micromachined Vibration Isolation Filters to Enhance Packaging for Mechanically Harsh Environments

Some harsh environments, such as those encountered by missiles, rockets and various types of industrial machinery, contain high frequency mechanical vibrations. Unfortunately, some very useful components are sensitive to these high frequency vibrations. Examples include MEMS gyroscopes, oscillators and some micro-optics. Exposure to high frequency mechanical vibrations present in the operating environment can result in problems ranging from an increased noise floor to component failure. Passive micromachined silicon lowpass filter structures (spring-mass-damper) have been demonstrated in recent years. Since they usually possess a low vertical profile, they can be utilized as the packaging substrate for the sensitive component requiring vibration isolation. The performance of these filter structures is typically limited by low damping and a lack of tunability after fabrication. However, filter performance can be enhanced by integrating fluidic damping techniques with the passive filter or by integrating a micromachined actuator with state feedback to realize an active filter. The active filter has the additional advantage of post fabrication tunability.