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For side airbag systems it is necessary to measure the acceleration within a time of less than 3 ms in order to inflate the side airbag in time. A new generation of side airbag sensors that uses a linear accelerometer is presented. The evaluation circuit includes amplification, temperature coefficient compensation, two wire unidirectional current interface, and a zero-offset compensation. The sensing element for the measurement of acceleration is a surface micromachined accelerometer. In order to minimise the production costs the surface micromachined sensor element and the corresponding evaluation ASIC are packaged into a standard PLCC28 housing. For the entire function only few external components are necessary. During the power-on cycle an internal selftest is carried out and the result is transmitted to the airbag control unit. Most important results of the characterisation are presented.

This paper reports on a new generation of silicon gyroscopes, which can be used as angular rate sensors for roll-over sensing or navigation control. The sensor is fabricated in standard Si-surface micromachining technology and encapsulated under vacuum conditions using an Si-micromachined cap wafer. The sensor consists of an electrostatically driven oscillating disk, which reacts with a tilt movement when an angular rate is applied due to the conservation law for angular momentums. The tilt movement is then detected capacitively by electrodes on the substrate underneath the oscillating disk. The sensor is packaged in a standard SMD housing (PLCC44).

A new generation of production-ready dual function sensor which combines a yaw rate sensor with a linear accelerometer, based on silicon micromachining, is presented. The sensor is designed for mass production and high performance applications such as vehicle control systems. A combination of surface and bulk micromachining leads to an advantage in design, signal evaluation and packaging. This paper discusses the design of the sensing elements: the yaw rate sensor consists of two bulk micromachined oscillating masses each of which supports a surface micromachined accelerometer for detection of the coriolis force. The sensing element for the linear acceleration is a separate surface micromachined accelerometer. The electrodynamic actuation and high Q-value of the oscillator allow packaging at atmospheric pressure. Characterization results of the device are presented.

A single-chip integrated barometric pressure sensor using bulk silicon micromachining will be presented in this paper. The sensor chip incorporates the complete signal evaluation and trimming of the temperature coefficients and manufacturing tolerances. Sensor chips are mounted onto 6″ × 4″ thick film substrates for batch processing during assembly and trimming. The separated, individual devices can be used for surface mounting (SMD) on a printed circuit board (PCB). Specifications for the sensor functions, as well as the assembly and packaging concept, will be discussed. Assembly, trimming and packaging are the most expensive production steps in the manufacture of sensors. In order to reduce the costs for sensors, we are introducing a standardization of sensor assembly and trimming with batch processing capability: after dicing, the integrated sensor chip is attached to a 6″ × 4″ thick film ceramic substrate with standard die-attaching glue.

Employing novel surface micromachining techniques, a highly miniaturized, robust device has been fabricated. The accelerometer fulfills all requirements of state-of-the-art airbag systems. The present paper reports on the manufacturing and assembly process as well as the performance of the sensor. The capacitive sensing element consists of a moveable proof mass of polysilicon on a single crystalline silicon substrate. A lateral acceleration displaces the proof mass and a capacitive signal is generated at a comb electrode configuration. An external IC circuit provides the signal evaluation and conditioning in a closed loop mode, resulting in low temperature dependency of sensor characteristics and a wide frequency response. The sensor is fabricated by standard IC processing steps combined with additional surface micromachining techniques. A special deposition process in an epitaxial reactor allows the fabrication of moveable masses of more than 10 µm thickness.

An integrated manifold pressure sensor using bulk silicon micromachining techniques is presented. The sensor incorporates the entire signal amplification, temperature compensation, and circuitry for electronic trimming of the sensor chip. The chip circuitry and the manufacturing and assembly process will be discussed. Trimming of the sensitivity and offset production tolerances as well as the temperature coefficients of sensitivity and offset is performed using an electrical trim method. A binary coded digital compensation information is serially fed into an on-chip control unit. The individual bits are decoded and sent to the gates of a bank of trimming thyristors. Once the correct binary code has been selected so that the sensor characteristic is centered in the specified range, the programming voltage is increased and the data is irreversibely stored similarly to the zener zapping method.