Flush-Mount Sensor Packaging for Superior Aeroacoustics Instrumentation

Batch Fabrication Decreases Cost Per Sensor, Lowering Aircraft Fuselage Array Expenses

This improved packaging design protects and optimizes microphone sensors that are used in and around airplanes to help locate and reduce excessive aviation noise, an environmental and human health hazard. Passenger travel in airplanes is expected to increase from 732 million to 1.2 billion by 2032, and the comfort and safety of these passengers and their pilots, as well as the communities surrounding commercial airports, are vital to the continued progress of commercial flight. Widely-used noise detection technologies sacrifice durability and sensitivity for low production costs. Unfortunately, no available cost-effective aeroacoustics instrumentation solutions simultaneously protect microphone sensors and maintain superior sensitivity. Researchers at the University of Florida have developed a superior instrumentation packaging design that decreases production costs without sacrificing instrument sensitivity. This allows for more accurate capture of noise information by the sensor by avoiding the need for a protective encapsulant that dampens differential airflow measurement by the instrument’s sensing processes and makes the diaphragm a direct part of the sensing side of the device, closer to the surface on which the measurement is desired. Additionally, the developed packaging design creates an overall flush front surface of the microphone package, minimizing the impact of the sensor on the measurement. This transformative change is part of a microfabrication system that allows for mass production of these superior sensors at a lower cost than available instrumentation with protective encapsulants.

Application

Sensor packaging for highly accurate aeroacoustics measurement

Advantages

• Lowers cost of sensor production, eliminating prohibitive replacement costs and need for challenging repair of existing sensor installations
• Uses ultra-thin sensors, reducing surface airflow interference between neighboring sensors and increasing array measurement sensitivity
• Avoids requirement to house diaphragm in a protective cavity, decreasing risk for freezing and sensor failure
• Creates an overall flush front surface of entire microphone package, minimizing protrusions into the measurement environment and subsequent effects on the desired measurement

Technology

This packaging design achieves high aeroacoustics instrumentation sensitivity through a microfabrication method that uses backside wire bonds. The sensor is microfabricated on a silicon-on-insulator wafer using through-silicon-vias, then enclosed in a shim cap and attached to a mounting substrate. This design allows the sensor surface to be a direct part of the exposed side of the sensor package – a “flush mount.” The resulting elimination of raised edges on the device eliminates their impact on airflow measurement by a particular sensor and surrounding sensors in an aircraft fuselage array installation. Additionally, microfabrication of the sensor minimalizes cost, allowing greater sensory density in array installations and increasing resolution capabilities for aircraft pressure maps.