Patent ID: 7140085

Claim:
A process for manufacturing a capacitive vacuum measuring cell, comprising the following steps: a. manufacturing a first Al 2 O 3 housing plate ( 1 ) with outer and inner opposing surfaces and an outer periphery; b. forming an electrically conductive surface ( 7 ) on the inner surface of the first Al 2 O 3 housing plate to provide a first electrode of the capacitive vacuum measuring cell; c. manufacturing a second Al 2 O 3 housing plate ( 4 ) with an outer periphery; d. forming an opening in the second Al 2 O 3 housing plate ( 4 ) extending therethrough; e. providing a connecting port ( 5 ) about the opening formed in the second Al 2 O 3 housing plate ( 4 ); f. manufacturing of an Al 2 O 3 membrane ( 2 ) having first and second opposing surfaces and an outer periphery, the membrane having a thickness within the range of 10 μm to 250 μm, the manufacture of the Al 2 O 3 membrane ( 2 ) including the steps of: i. forming the Al 2 O 3 membrane ( 2 ) from an Al 2 O 3 slurry; ii. heating the membrane in a furnace a first time to sinter the membrane, with subsequent cool-down; and iii. heating the membrane a second time for smoothing the membrane, with subsequent cool down; g. forming an electrically conductive film ( 7 ) on the first surface of the Al 2 O 3 membrane ( 2 ) to provide a second electrode of the capacitive vacuum measuring cell; h. disposing the Al 2 O 3 membrane ( 2 ) between the inner surface of the first Al 2 O 3 housing plate ( 1 ) and the second Al 2 O 3 housing plate ( 4 ), with the first surface of the Al 2 O 3 membrane ( 2 ) facing the inner surface of the first Al 2 O 3 housing plate ( 1 ), and spacing the first surface of the Al 2 O 3 membrane ( 2 ) at a predetermined distance from the inner surface of the first Al 2 O 3 housing plate ( 1 ) to define a reference vacuum chamber ( 25 ) therebetween, and spacing the second Al 2 O 3 housing plate ( 4 ) at a predetermined distance from the second surface of the Al 2 O 3 membrane ( 2 ) to define a measurement vacuum chamber ( 26 ) therebetween; and i. sealing the outer periphery of the Al 2 O 3 membrane ( 2 ) to the outer peripheries of the first Al 2 O 3 housing plate ( 1 ) and the second Al 2 O 3 housing plate ( 4 ) to form a vacuum tight seal therebetween.