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METHOD FOR PRODUCING CAPACITIVE CERAMIC ABSOLUTE PRESSURE SENSORS SORTED IN ZERO-POINT LONG-TERM STABILITY DEFECT CLASSES
METHOD FOR PRODUCING CAPACITIVE CERAMIC ABSOLUTE PRESSURE SENSORS SORTED IN ZERO-POINT LONG-TERM STABILITY DEFECT CLASSES
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机译：零点长期稳定性缺陷类别中产生的电容式陶瓷绝对压力传感器的制造方法
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摘要
In this method for producing capacitive alumina-ceramicabsolute pressure sensors sorted in high-precisionzero-point long-term stability defect classes referred to ameasured-value span csp, the sensors are firstly producedconventionally: a substrate is provided with an annularfirst electrode and, at the center, a circular secondelectrode insulated from the first; a diaphragm is providedwith a third electrode, and the substrate and diaphragm arejoined tightly together in a vacuum by the mutually facingelectrodes, at an outer edge through the interposition ofan active brazing ring with the formation of a chamber,with the result that a pressure-dependent capacitance Cpand a pressure-independent capacitance Cr are produced.Then, using the equation c = (Cp-Cr)/Cp = k1(p-p0)+k0, atroom temperature and under a vacuum (= p -- 0 ) a firstzero value cn2 = -k1p0+k0 is determined by means of acapacitance zero-point measuring device having thezero-point measuring error Fn. A second zero valuecn2 = -k1p0 ' +k0 is determined f or each sensor by means ofthe same measuring device after the sensors have beenstored in a gas during a period t in such a way that thepressure and/or temperature of the gas was raised, or itsmolecular weight was lowered, with respect to normalatmospheric conditions. Then the difference .delta.cn between thefirst and second zero values .delta.cn = cn1 - cn2 k1.delta.p0 isformed, and the value .delta.cn/csp is compared with the valueFn/csp. It is also possible to make use analogously of thezero-point temperature coefficient.
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