Analytical Shear Lag Modeling for Strain Transmission into Bottom Terminated Packages
Analytical shear lag models quantify strain transfer from boards to bottom-terminated packages, showing compliant die attach drops offset drift by 98 percent.
MEMS Sensor Drift
Performance Degradation
Gradual deviation in the output of a micro-electromechanical transducer under constant input conditions arises from material aging and environmental exposure. Engineers characterize MEMS sensor drift to maintain long-term accuracy in inertial measurement units and pressure sensing arrays.
Physical Mechanism
Stress relaxation in the silicon substrate and the gradual degradation of packaging materials alter the mechanical properties of the sensing microstructure. These microscopic changes affect the spring constant and the capacitance of the sensing elements. Additionally, thermal cycling accelerates the redistribution of internal stresses, causing further variation in the baseline signal.
Metrological Compensation
Calibration laboratories implement mathematical compensation algorithms to counteract this slow variation. These algorithms use temperature data from integrated sensors to adjust the baseline output dynamically.
Testing Constraint
Sufficiently long testing periods are required to separate the slow long-term drift from high-frequency noise and short-term thermal fluctuations. The measurement must be conducted in an environment with high temperature stability to ensure that thermal effects do not mask the drift. If the ambient temperature is not controlled to within a fraction of a degree, the resulting dataset will yield inaccurate drift coefficients.
Therefore, specialized climate chambers are essential for the qualification of high-precision inertial sensors.