Mechanical Shield
Micromachined mechanical suspension structures embedded within sensor packages isolate active sensing elements from external mechanical strain and thermal board warping. Precision inertial measurement packages incorporate a stress isolation frame to decouple fragile silicon proof masses from exterior package deformation. The structural frame governs stress attenuation factors, resonance frequency modes and mechanical shock survivability.
Boundary limits end at structural deflection limits where the frame contacts surrounding package walls during severe mechanical shock events.
Structural Compliance
Flexible silicon beam flexures absorb package strain while maintaining high structural stiffness along intended sensing axes. Design geometry of the stress isolation frame attenuates mechanical strain transmitted from circuit board flexing or mounting bolt torque. Structural damping prevents external acoustic vibration from exciting frame mechanical resonance modes.
Offset Drift
Board bending forces transferred directly to sensor dies induce piezoresistive zero-offset drift in strain measurement circuits. Implementation of a stress isolation frame prevents substrate deformation from shifting baseline sensor output values. Reduced mechanical stress preserves factory calibration accuracy across varying board installation configurations.
Mechanical Qualification
Finite element analysis models strain transmission through the isolation structure under simulated mounting torques. Physical testing subjects the stress isolation frame to mechanical bending loads while monitoring sensor offset output stability. Laser Doppler vibrometry verifies that frame resonant frequencies remain well outside operational vibration spectra.
