Isolating Micro-Machined Accelerometer Zero-G Bias Shifts under Static Thermal Cycles
Static thermal zero-g bias shifts in MEMS accelerometers are isolated by enforcing prolonged thermal dwell periods to decouple stress creep from thermal gradients.
Hermetic Ceramic Package
Protective Enclosure
Protective enclosure designed to maintain a vacuum or controlled atmosphere around sensitive electronic components. A hermetic ceramic package prevents the ingress of moisture and corrosive gases that degrade semiconductor junctions. The structure utilizes alumina or aluminum nitride to provide high thermal conductivity and electrical isolation.
Seal Integrity
Strength of the barrier depends on the glass-to-metal or gold-tin solder seals at the lid interface. Testing the hermetic ceramic package involves helium leak detection and gross leak bubbling to verify the internal cavity remains isolated from the external environment. These seals must withstand high pressure and thermal shock without cracking.
Material Properties
Inorganic construction offers superior stability compared to organic plastic alternatives. The hermetic ceramic package does not outgas or absorb moisture, which makes it suitable for high-reliability aerospace and medical applications. Because the coefficients of thermal expansion are matched to the silicon die, the package reduces mechanical stress during power cycling.
Environmental Boundary
Performance limits are defined by the maximum operating temperature and the pressure differential the walls can support. While the hermetic ceramic package is impervious to gas diffusion, it is susceptible to brittle fracture under extreme mechanical impact. Designers must account for the added mass and volume of the ceramic compared to thinner plastic surface-mount technologies when calculating the final board density.