Protection Barrier
Environmental encapsulation systems for micro scale sensing elements provide mechanical protection and electrical connectivity while maintaining the sensitivity of the device to the target measurand. Deployment of thin film sensor packaging must shield the delicate layers from moisture and chemicals without introducing excessive stress or thermal lag. The design of this package necessitates a compromise between isolation from the environment and access to the signal of the measurement.
Signal Path
Electrical connections are made through thin film traces that lead to bond pads at the edge of the device. These paths must have low resistance and be strong enough to withstand the subsequent wire bonding or flip chip assembly. Reliable contact is necessary to ensure that the sensor output is not distorted by parasitic resistance.
Assembly Tolerance
Alignment of the sensor within the final housing requires precision to avoid shading or uneven loading. Small variations in the position of the chip can lead to errors in the measured value or premature failure of the interconnects. Testing protocols verify the integrity of the seal and the accuracy of the calibration after the packaging process is complete.
Thermal Management
Heat dissipation is managed through the choice of substrate and the thickness of the encapsulation layers. High thermal conductivity is required to prevent local overheating of the sensor.
