Meaning
Time-dependent reduction in internal mechanical stress under constant strain alters the structural stability of materials over their operational life. In piezoelectric devices, stress relaxation in the mounting structures of the crystal can cause minor frequency shifts as the component ages. This phenomenon is a primary driver of long-term frequency drift in oscillators.
Packaging Strain
Mounting materials must be selected to resist mechanical deformation over time. Solder alloys and conductive adhesives that exhibit minimal stress relaxation are used to secure the crystal. This selection ensures that the mechanical load on the quartz remains stable.
Yield Analysis
Long-term reliability testing under thermal stress allows manufacturers to predict frequency drift. Monitoring how stress relaxation affects the mounting structure helps in refining the assembly process. This refinement reduces the rate of warranty claims.
Warranty Protection
Commercial contracts protect the purchaser by defining maximum limits for frequency drift over a multi-year period. When stress relaxation causes the device to drift beyond the specified frequency tolerance, the manufacturer is obligated to replace the failed units. These agreements often detail the accelerated aging tests used to simulate long-term performance before shipment.
This ensures that the components will perform reliably throughout the product’s lifespan.
