Piezoresistive Response
Doped semiconductor resistors alter electrical resistivity in response to applied mechanical strain. Packaging forces and thermal expansion differentials induce piezoresistive stress coupling that generates spurious resistance changes unrelated to measured physical quantities. Differential pressure sensors and strain gauges experience zero-offset drift when package stress alters Wheatstone bridge balance.
Metrology qualification protocols measure sensor output shifts under varying packaging torque and thermal bias to isolate parasitic stress sensitivity.
Stress Transmission
External mounting torque deforms sensor housings and transmits shear stress through die attach layers to embedded silicon resistors. Temperature variations exacerbate these stress fields due to thermal expansion coefficient mismatches between silicon die and metal housing components. Tensor equations describe the relationship between multi-axial stress components and local resistivity changes across crystallographic planes.
Crystal orientation choices like selecting one-zero-zero or one-one-one wafer planes help minimize parasitic stress coefficients along non-sensing axes.
Sensor Drift
Unintended packaging stress alters zero-pressure output voltages, degrading measurement accuracy. Mechanical relaxation of package seals over operational life causes long-term offset drift in field installations.
Isolation Control
Compliant isolation diaphragms and stress-relieving gel fills decouple sensing die from rigid external housings. Quality assurance procedures verify zero-offset stability after applying maximum mounting torque during instrument installation.
