Meaning
Resonant frequency sensitivity to external force is a mechanical property of piezoelectric materials. The stress frequency effect describes how force applied to the resonator plate alters the internal elastic properties and shifts the output frequency.
Mechanical Sensitivity
Mounting design and adhesive selection are critical to isolating the crystal from external forces. If the package is subjected to temperature changes, the different expansion rates of the materials can apply stress to the crystal through its supports. This stress frequency effect causes a predictable shift in frequency that must be compensated for in the design.
Engineers use flexible mounting structures to minimize this mechanical coupling.
Oscillator Performance
Timing precision is compromised when mechanical vibrations or shock affect the oscillator. In high-vibration environments, the stress frequency effect leads to phase noise and short-term frequency instability. This instability degrades the signal quality in communication links and can cause synchronization errors.
High-performance systems use stress-compensated crystal cuts to mitigate this degradation.
Quality Assurance
Distribution contracts for high-reliability components specify the allowable frequency deviation under mechanical stress. Manufacturers must perform stress testing to ensure that the delivered devices do not exceed the specified drift limits. If a batch fails this testing, the distributor can reject the shipment under the terms of the quality agreement.
This contract clause protects the distributor and their customers from receiving unstable components.
