| 摘要 |
In this method for producing capacitive alumina-ceramic absolute pressure sensors sorted in high-precision zero-point long-term stability defect classes referred to a measured-value span csp, the sensors are firstly produced conventionally: a substrate is provided with an annular first electrode and, at the center, a circular second electrode insulated from the first; a diaphragm is provided with a third electrode, and the substrate and diaphragm are joined tightly together in a vacuum by the mutually facing electrodes, at an outer edge through the interposition of an active brazing ring with the formation of a chamber, with the result that a pressure-dependent capacitance Cp and a pressure-independent capacitance Cr are produced. Then, using the equation c=(Cp-Cr)/Cp=k1(p-p0)+k0, at room temperature and under a vacuum (=p->0) a first zero value cn1=-k1p0+k0 is determined by means of a capacitance zero-point measuring device having the zero-point measuring error Fn. A second zero value cn2=-k1p0'+k0 is determined for each sensor by means of the same measuring device after the sensors have been stored in a gas during a period t in such a way that the pressure and/or temperature of the gas was raised, or its molecular weight was lowered, with respect to normal atmospheric conditions. Then the difference delta cn between the first and second zero values delta cn=cn1-cn2=-k1 delta p0 is formed, and the value delta cn/csp is compared with the value Fn/csp. It is also possible to make use analogously of the zero-point temperature coefficient.
|
