SENSOR FOR DETECTING A PRESSURE OF A FLUID MEDIUM

Abstract

A sensor for detecting a pressure of a fluid medium is provided. The sensor includes a sensor element for detecting the pressure of the fluid medium, a supply duct for supplying the fluid medium to the sensor element and a control and/or evaluation circuit for processing signals of the sensor element. The control and/or evaluation circuit is situated on the sensor element.

Claims

1. A sensor for detecting a pressure of a fluid medium, comprising: a sensor element to detect the pressure of the fluid medium; a supply duct to supply the fluid medium to the sensor element; and at least one of a control and evaluation circuit, the at least one of the control and evaluation circuit to process signals of the sensor element, wherein the at least one of the control and evaluation circuit is situated on the sensor element.

2. The sensor as recited in claim 1, wherein the at least one of the control and evaluation circuit is situated directly on the sensor element.

3. The sensor as recited in claim 1, wherein the at least one of the control and evaluation circuit is situated on the sensor element in such a way that the at least one of the control and evaluation circuit together with the sensor element encloses a cavity.

4. The sensor as recited in claim 1, wherein the at least one of the control and evaluation circuit has a recess on a front side facing the sensor element, the recess being closed by the sensor element to form the cavity.

5. The sensor as recited in claim 1, wherein the at least one of the control and evaluation circuit is situated on a back side of the sensor element facing away from the supply duct.

6. The sensor as recited claim 1, wherein the sensor element and the at least one of the control and evaluation circuit are arranged in a longitudinal extension direction, a cross-sectional area of the at least one of the control and evaluation circuit perpendicular to longitudinal extension direction being smaller than a cross-sectional area of the sensor element perpendicular to the longitudinal extension direction.

7. The sensor as recited in claim 6, wherein the at least one of the control and evaluation circuit is electrically connected to the sensor element.

8. The sensor as recited in claim 7, wherein at least one connection contact is situated on the back side of the sensor element, the at least one of the control and evaluation circuit being electrically connected to the connection contact by way of at least one bonding wire.

9. The sensor as recited in claim 8, wherein the connection contact with respect to the longitudinal extension direction is located next to the at least one of the control and evaluation circuit.

10. The sensor as recited in claim 1, wherein the sensor element is a silicon chip.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0016] Additional optional details and features of the present invention result from the following description of preferred exemplary embodiments, which are shown schematically in the figure.

[0017] FIG. 1 shows a longitudinal cross section of a sensor according to the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0018] FIG. 1 shows a longitudinal cross section of a sensor 10, according to the present invention, for detecting a pressure of a fluid medium. Sensor 10 may be designed for example for detecting a pressure of fuel in a fuel line of an internal combustion engine or of exhaust gases in the exhaust gas flow of an internal combustion engine. In this instance, only a portion of the components of sensor 10 is depicted. Additional components such as housing, threaded component, housing base, plug connector, for example, are not shown.

[0019] Sensor 10 includes a sensor element 12. Sensor element 12 is a silicon chip. Sensor element 12 has a front side 14 and a back side 16. A recess 18 is developed in front side 14. A section of sensor element 12 having a reduced material thickness above recess 18 forms a deformable diaphragm 20. On diaphragm 20 or back side 16, multiple piezoresistive elements (not shown) are situated in the form of a measuring bridge, for example in the form of a Wheatstone bridge.

[0020] Sensor element 12 is situated with front side 14 on a base 22, for example a glass base or a plastic base. Sensor element 12 is firmly connected to base 22, for example bonded. A supply duct 24 for supplying the fluid medium to sensor element 12 is developed in base 22. Supply duct 24 is connected to recess 18.

[0021] Sensor 10 furthermore includes a control and/or evaluation circuit 26. Control and/or evaluation circuit 26 is an ASIC. Control and/or evaluation circuit 26 is situated on sensor element 12. More precisely, control and/or evaluation circuit 26 is situated on the back side 16 of sensor element 12 facing away from supply duct 24. Control and/or evaluation circuit 26 is in particular situated directly on sensor element 12 and is fastened on the latter, for example by adhesive.

[0022] Control and/or evaluation circuit 26 is situated on sensor element 12 in such a way that control and/or evaluation circuit 26 together with sensor element 12 encloses a cavity 28. Cavity 28 is used for example as a reference volume for an absolute pressure measurement. This may be achieved for example in that control and/or evaluation circuit 26 has a recess 32 on a front side 30 facing sensor element 12. Recess 32 is closed by sensor element 12 to form cavity 28.

[0023] Accordingly, sensor element 12 and control and/or evaluation circuit 26 are arranged in a longitudinal extension direction 34.

[0024] A cross-sectional area 36 of control and/or evaluation circuit 26 perpendicular to longitudinal extension direction 34 is smaller than a cross-sectional area 38 of sensor element 12 perpendicular to longitudinal extension direction 34. In other words, control and/or evaluation circuit 26 is smaller than sensor element 12. This creates room for an electrical connection of control and/or evaluation circuit 26 to sensor element 12. For example, at least one connection contact 40 is situated on the back side 16 of sensor element 12. Control and/or evaluation circuit 26 is in turn electrically connected by way of a bonding wire 42 to connection contact 36 and thus to sensor element 12.

[0025] With respect to longitudinal extension direction 34, connection contact 40 is situated next to control and/or evaluation circuit 26 and thus outside of cavity 28.

[0026] Control and/or evaluation circuit 26 is furthermore electrically connected to a circuit substrate (not shown), such as a circuit board for example, for example by way of bonding wires. The circuit substrate is situated for example laterally next to control and/or evaluation circuit 26 or sensor element 12. In other words, the circuit substrate maybe situated at a position that is at a distance from control and/or evaluation circuit 26 or sensor element 12 in a direction perpendicular to longitudinal extension direction 34. In this instance, the circuit substrate itself may be oriented perpendicularly to longitudinal extension direction 34 or extend perpendicularly to longitudinal extension direction 34. Alternatively, the circuit substrate may be situated above control and/or evaluation circuit 26. In other words, the circuit substrate maybe situated at a position that is at a distance from control and/or evaluation circuit 26 in a direction parallel to longitudinal extension direction 34. In this instance, the circuit substrate itself may be oriented in parallel to longitudinal extension direction 34 or extend perpendicularly to longitudinal extension direction 34. Alternatively, the circuit substrate may also be situated partially on control and/or evaluation circuit 26. In other words, the circuit substrate may have a section that is situated directly on control and/or evaluation circuit 26 and may be connected to the latter. In this instance, the circuit substrate may be oriented perpendicularly to longitudinal extension direction 34 or extend perpendicularly to longitudinal extension direction 34.

[0027] Furthermore, control and/or evaluation circuit 26 and connection contact 40 are protected against corrosion, for example by a gel. The above-described construction, according to the present invention, of sensor 10 is demonstrable particularly after removal of the gel.