A PRESSURE SENSOR AND A METHOD OF MANUFACTURING A PRESSURE SENSOR

Title:

A PRESSURE SENSOR AND A METHOD OF MANUFACTURING A PRESSURE SENSOR

Document Type and Number:

WIPO Patent Application WO1999032866

Kind Code:

A3

Abstract:

A capacitive pressure sensor of substantially ceramic material comprises a thick base plate (100), a front plate (140) having the same thickness as the base plate and a movable diaphragm (120) located between the front plate and the base plate. Capacitor electrodes (121b, 121a) are provided at the surface of the diaphragm facing the base plate and form a measurement capacitor. The diaphragm (120) is extremely thin and is produced by sintering a ceramic material such aluminium oxide. Owing to a pressing process used during the sintering a strong, very thin diaphragm is obtained having no mechanical stresses and fracture indications. It can be produced to have a very small thickness in order to provide pressure sensors having a high sensitivity, which can also for high-vacuum applications tolerate to be subjected to the atmospheric pressure. A shielding plate (110) can be inserted between the base plate (100) and the diaphragm (120) in order to provide both electrical shielding and to form a reference capacitor having a reference pressure for compensating the measurement capacitor. The shielding plate (110) can also be extremely thin, having a thickness down to a thickness corresponding to the thickness of the diaphragm (120).

Inventors:

JONSSON STAFFAN (SE)

Application Number:

PCT/SE1998/002441

Publication Date:

August 26, 1999

Filing Date:

December 22, 1998

Export Citation:

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Assignee:

CECAP AB (SE)
JONSSON STAFFAN (SE)

International Classes:

G01L9/00; G01L13/02; (IPC1-7): G01L9/12

Foreign References:

US4425799A	1984-01-17
EP0490807A2	1992-06-17
US5499158A	1996-03-12
US4769738A	1988-09-06
US5485345A	1996-01-16
US4587851A	1986-05-13

Other References: