High Reliability Absolute Semiconductor Pressure Sensor

This paper describes an absolute semiconductor pressure sensor suitable for the engine control systems in automobiles. Using the passive (electrically nonconnected) side of a sensor chip as the pressure interface, it has good pressure media compatibility. But it requires a pedestal with a pressure inlet hole and a larger contact area for good sealed, vacuum reference, since the larger contact area causes a larger temperature shift of the offset voltage due to thermal stress. We have analyzed the thermal stress by the finite element method and have designed a lower, tubular pedestal with a groove which has isolated the sensor chip from the thermal stress more effectively.

As a result, the sensor chip has been assembled in a standard TO-5 package and a temperature shift of the offset voltage within ±1% error of FS (Full Scale) without temperature compensation in the temperature range of -30°C to 100°C has been realized.