Method of making an acceleration sensor

• US 5,310,450 A
• Filed: 06/17/1992
• Issued: 05/10/1994
• Est. Priority Date: 07/06/1991
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Offenberg, Michael, Willmann, Martin
• Primary Examiner(s): Powell, William A.
• Application Number:
  US07/900,187
• Time in Patent Office: 692 Days
• Field of Search: 156/629, 156/630, 156/633, 156/647, 156/651, 156/657, 156/659.1, 156/662, 73/517 R, 437/901, 437/921, 148/DIG. 159
• US Class Current: 216/2
• CPC Class Codes: G01P 15/0802 Details
• CPC Class Codes: G01P 2015/0828 the mass being of the paddle type being suspended at one of its longitudinal ends
• CPC Class Codes: Y10S 148/159 Strain gauges

Abstract

A method of making acceleration sensors with integrated measurement of internal pressure includes connecting multiple plates to each other, thereby defining internal cavities. The tightness of these connections or bonds is checked and controlled during the manufacturing process. The plates define membrane portions adjacent each cavity, the membranes deforming in accordance with the internal pressure in the adjacent cavity. Preferably, the internal pressure of the sensor is measurable by detecting deformation of a sensor wall which defines a membrane.

Claims

1. Method of making an acceleration sensor, comprising

connecting together at least an upper plate (3) and a lower plate (2), and

forming a cavity (4) between said plates,

in such a way that

at least one of said plates (2, 3) defines a membrane (5) which deforms in response to an internal pressure in said cavity, thereby facilitating immediate detection of any faulty connection between said plates.

3. Method according to claim 1, further comprising

forming said cavity (4) adjacent multiple plates.

4. Method according to claim 1, further comprising

providing a sensor element (1) inside said cavity (4).

5. Method according to claim 1, comprising

forming at least two of said cavities (4), of which merely a portion have a membrane, and providing sensor elements (1) in a portion without any membrane.

6. Method according to claim 1, wherein

said plates are processed by masking and etching steps.

7. Method according to claim 1, comprising

providing an intermediate plate (8) between said lower plate (2) and said upper plate (3), and

forming said sensor element (1) from said intermediate plate.

8. Method according to claim 7, comprising

forming at least one further cavity (9), and

forming a membrane (5) in said intermediate plate (8) adjacent said at least one further cavity (9).

2. Method of making an acceleration sensor, comprising

connecting together at least an upper plate (24), a lower plate (21), and at least one intermediate plate (22, 23), and

forming a cavity (26, 27) between said plates,

in such a way that

at least one of said plates (22,23) defines a membrane (5) which deforms in response to an internal pressure in said cavity, and

forming respective openings (7) adjacent each membrane (5), so that all of said membranes (5) are accessible from outside.