Pedestal Mounting Configuration
Pedestal mounting for a micro-electromechanical resonator utilizes a single, localized point of attachment to the substrate. The implementation of a single center anchor allows the surrounding structure to expand and contract symmetrically without inducing bending moments. This configuration is particularly effective for disk resonators and other radial vibrating structures that require high isolation from external stresses.
Symmetry Advantage
Expansion of the wafer often causes large packaging stress that can shift the frequency of a sensor. A single center anchor ensures that these forces act equally in all directions from the center of the proof mass. Such symmetry minimizes the bias drift caused by temperature fluctuations in the environment.
High-precision gyroscopes rely on this mounting technique to maintain a stable null point during operational temperature cycles.
Energy Retention
Retention of energy is measured by the quality factor, which indicates how much energy is lost to the surroundings. Using a single center anchor reduces the path for acoustic energy to leak into the substrate. Minimal contact area between the vibrating mass and the stationary chip results in higher Q-factors and lower phase noise.
Engineers verify the anchor’s effectiveness by measuring the damping ratio of the device in a vacuum.
Integrity Limit
Structural integrity may be lower in devices that rely on only one point of support. A single center anchor must be sized to withstand mechanical shocks without fracturing.
