Boeing utilizes many different sensor types and their associated electronic systems for aircraft testing. An array of Micro-Electro-Mechanical System (MEMS) sensors are being used to determine the load on aircraft wings. This paper reports the development of a 'pressure belt' containing MEMS pressure sensors and multi-chip modules (MCMs) on a flexible printed circuit card. A thickness of less than 0.070 inch was required for aerodynamic reasons. The MCM substrate was fabricated on oxidized silicon using copper as the conductor and photo-sensitive polyimide as the dielectric material. A direct-chip-attachment process was used to bond the MEMS device to the module and the bus connection was conducted through the flexible circuit card to the host computer. An encapsulation material for the protection of the bare electronic components was selected for improving the reliability of the module. The signal conditioning unit includes analog to digital conversion. It also contains a digital filter and logic to perform temperature compensation and conversion of the output into engineering units. Laboratory experiments using these designs were found to be within 0.1% full scale accuracy. Design details of these improvements will be presented along with a discussion on the physical configuration of the pressure belt.
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