WO2020058512A1

WO2020058512A1 - Sensor apparatus

Info

Publication number: WO2020058512A1
Application number: PCT/EP2019/075414
Authority: WO
Inventors: Randy Hsu
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-09-21
Filing date: 2019-09-20
Publication date: 2020-03-26
Anticipated expiration: 2021-03-21
Also published as: CN208721114U

Abstract

The present utility model discloses a sensor apparatus, comprising: a substrate, comprising a first face and a second face opposite each other, and being provided with a through-hole in communication with the first face and the second face; an insert, inserted in the through-hole and comprising a first gas-penetrable opening; and a sensing element, mounted in a sealed manner on the first face of the substrate, with a first space and a second space being formed at two sides of the sensing element, the first space and the second space being isolated from one another in a gas-impermeable fashion, and the first gas-penetrable opening being in communication with the first space and the second face. The sensor apparatus according to the present utility model has a simple and reliable structure, and can prevent chemical reactions from occurring between the substrate and media in harsh operating environments, thereby increasing the measurement precision and service life of the sensor apparatus.

Description

D e s c r i p t i o n

Sensor apparatus

Technical field

The present utility model relates to a sensor apparatus, in particular to a structure of a MEMS-based sensor apparatus.

Background art

Sensors in Micro Electro-Mechanical System (MEMS) technology, after being packaged, are capable of protecting chips. Sensors need to sense changes in the external environment and realize the function of leading out electrical signals, and it is therefore necessary for a pathway in direct connection with the outside to be retained on a sensor casing or support plate, for the purpose of sensing physical information such as light, heat, gas pressure and force. For example, the casing of a MEMS differential pressure sensor (DFS) used in exhaust treatment of a vehicle driven by an internal combustion engine must have an opening capable of sensing external gas pressure; at the same time, an opening is provided on a substrate, facing a MEMS chip, the opening running through the substrate, for sensing external gas pressure.

The opening in the substrate is generally made by laser cutting or machining. However, the process of forming the opening readily causes the formation of micro-cracks, and/or a phase causing organic material to be damaged more easily, on a surface of the substrate formed of organic material. Laser cutting or machining in particular will damage the intrinsic robustness of the organic material towards acids; when the sensor is used in an acid medium environment, e. g. in the environment of exhaust gas of a vehicle driven by an internal combustion engine, a cut surface that has not undergone treatment such as metal electroplating is easily chemically corroded and eroded. This chemical corrosion and erosion will change the characteristics of the substrate, e. g. cause expansion of the substrate in a region close to the opening running through the substrate; this might lead to a fault in the MEMS differential pressure sensor, and shortens the service life of the MEMS differential pressure sensor.

Content of the utility model

An object of the present utility model is to provide a sensor apparatus having good robustness towards harsh environments.

A sensor apparatus according to an embodiment of the present utility model comprises: a substrate, comprising a first face and a second face opposite each other, and being provided with a through-hole in communication with the first face and the second face; an insert, inserted in the through-hole and comprising a first gas-penetrable opening; and a sensing element, mounted in a sealed manner on the first face of the substrate, with a first space and a second space being formed at two sides of the sensing element, the first space and the second space being isolated from one another in a gas- impermeable fashion, and the first gas-penetrable opening being in communication with the first space and the second face.

Furthermore, the sensor apparatus further comprises a cover mounted on the first face of the substrate, with an accommodating space being formed between the cover and the substrate, and the sensing element being located in the accommodating space.

Furthermore, the second space is located between the cover and the sensing element, and the cover is provided with a second gas- penetrable opening in communication with the second space.

Furthermore, the sensor apparatus further comprises a gel filler, which at least partially fills the second space; the gel filler covers the sensing element.

Furthermore, the gel filler is a liquid fluoroelastomer.

Furthermore, the insert is formed of epoxy resin.

Furthermore, the width of the insert in a direction

perpendicular to the through-hole is 2 - 4 times the diameter of the first gas-penetrable opening.

Furthermore, the substrate is a ceramic circuit board, having an electrically conductive element which is disposed on the first face and electrically connected to the sensing element.

Furthermore, the sensing element is a MEMS differential pressure sensing element. Furthermore, the sensing element is a MEMS liquid level sensing element.

It can be seen from the above that the sensor apparatus according to the present utility model has a simple and reliable structure, and can prevent chemical reactions from occurring between the substrate and media in harsh operating environments, thereby increasing the measurement precision and service life of the sensor apparatus.

Description of the accompanying drawings

Features, characteristics, advantages and benefits of the present utility model will become obvious through the following detailed description, which makes reference to the accompanying drawings.

Fig. 1 shows a sectional view of a sensor apparatus according to an embodiment of the present utility model.

Fig. 2 shows a bottom view of the sensor apparatus according to an embodiment of the present utility model in fig. 1.

Fig. 3 shows a sectional view of a differential pressure sensor apparatus according to an embodiment of the present utility model.

Particular embodiments Embodiments of the present utility model are described in detail below with reference to the accompanying drawings.

Referring to figs. 1 and 2, a sensor apparatus according to an embodiment of the present utility model is shown. As shown in the figures, the sensor apparatus 10 comprises a substrate 11, a sensing element 12 and an insert 13. The substrate 11 is a ceramic circuit board, comprising a first face 111 and a second face 112 arranged opposite each other, and a through-hole 14 in

communication with the first face 111 and the second face 112. The sensing element 12 is mounted in a sealed manner on the first face 111 of the substrate 11; the sensor apparatus 10 forms a first space 15 and a second space 16, which are isolated from one another in a gas-impermeable fashion, at two sides of the sensing element 12. The substrate 11 also has an electrically conductive element 17, which is disposed on the first face 111 and

electrically connected to the sensing element. The insert 13 is formed of epoxy resin, and inserted in the through-hole 14 of the substrate 11. The insert 13 comprises a first gas-penetrable opening 18, which is in communication with the first space 15 and the second face 112. The first gas-penetrable opening 18 is arranged to face the sensing element 12. The width of the insert 13 in a direction perpendicular to the through-hole 14 is 2 - 4 times the diameter of the first gas-penetrable opening 18.

Those skilled in the art should understand that in order to safeguard normal operation of the sensing element 12 in a harsh operating environment, a protective member such as a gel filler could also be used to protect the sensing element 12. The gel filler at least partially fills the second space 16, covering the sensing element 12 and/or the electrically conductive element 17 which is disposed on the first face. The gel filler has an electrically insulating characteristic, and is used to protect the sensing element 12 from the effects of medium contaminants that are introduced. The gel filler is a colloidal suspension of a liquid in a solid, in order to form a colloidal material that is closer than a solution to a solid form; the gel filler can isolate a fluid pressure sensing element from a harsh surrounding

environment, and at the same time can precisely transmit to the sensing element 12 pressure applied by an external medium.

In the sensor apparatus 10 of this embodiment, the sensing element 12 is a MEMS fluid pressure sensing element, used for measuring the pressure of an external medium such as air or a liquid. Specifically, an external medium located in the first space 15 is in contact with the sensing element 12 via the first gas-penetrable opening 18 in communication with the first space 15 and the second face 112; the sensing element 12 senses the pressure of the external medium via the first gas-penetrable opening 18. The electrically conductive element 17, which is disposed on the first face 111 and electrically connected to the sensing element 12, converts the pressure of the external medium sensed by the sensing element 12 to an electrical signal for output. By providing the insert 13 on the substrate 11, the conditions of the substrate 11 at an edge of the through-hole 14 are changed, achieving a firmer surface texture and/or ceramic phase of the substrate 11, and thereby improving the robustness of the substrate 11 when operating in a harsh operating environment; for example, it may be used to measure the pressure of an acid medium in an acid environment.

In addition, those skilled in the art should understand that the sensor apparatus 10 of this embodiment may also be used to measure the pressure of a medium located in the second space 16.

At the same time, through cooperation with the electrically conductive element 17 disposed on the first face 111, the sensor apparatus 10 of this embodiment is also used to compare medium pressures located in the first space 15 and the second space 16. For example, a pressure difference of media located in the first space 15 and the second space 16 is compared.

Fig. 3 is a MEMS differential pressure sensor apparatus 20 according to an embodiment of the present utility model, which may for example be used as a differential pressure sensor in an exhaust system of a vehicle driven by an internal combustion engine, to measure a pressure drop over a fuel particulate filter. The differential pressure sensor apparatus comprises a substrate 21, a pressure sensing element 22 and a cover 23. The substrate 21 is a ceramic circuit board, comprising a first face 211 and a second face 212 arranged opposite each other, and a through-hole 24 in communication with the first face 211 and the second face 212. The pressure sensing element 22 is mounted on the first face 211 of the substrate 21, by means of a sealant or any other suitable bonding material, and the MEMS differential pressure sensor apparatus 20 forms a first space 25 and a second space 26, which are isolated from one another in a gas-impermeable fashion, at two sides of the pressure sensing element 22.

The substrate 21 also has an electrically conductive element 27 disposed on the first face 211; the electrically conductive element 27 is electrically connected to the pressure sensing element 22 via a conductive wire 28.

The cover 23 is disposed on the first face 211 of the

substrate 21; the cover 23 is arranged around the pressure sensing element 22, and forms an accommodating space, i. e. the second space 26, between itself and the substrate 21. The pressure sensing element 22 is located in the accommodating space. A gel filler 29 is packed in the accommodating space. The gel filler 29 has an electrically insulating characteristic, and covers the pressure sensing element 22, the electrically conductive element 27 and at least a part of the first face 211 of the substrate 21. In this embodiment, the gel filler 29 is used to protect the pressure sensing element 22 from the effects of medium

contaminants that are introduced. The cover 23 keeps the gel filler 29 at a suitable position. The gel filler 29 is a colloidal suspension of a liquid in a solid, in order to form a colloidal material that is closer than a solution to a solid form; the gel filler 29 can isolate the pressure sensing element 22 from a harsh surrounding environment, and at the same time can precisely transmit pressure applied by an external medium. The gel filler may for example be a liquid fluoroelastomer, which remains soft within a temperature range of -40° C to +135° C, and does not apply additional pressure to the pressure sensing element 22. Furthermore, the gel filler 29 is also used to isolate fuel particulates and other particulates, to prevent the fuel

particulates and other particulates from damaging the pressure sensing element 22 and/or causing the pressure sensing element 22 to operate abnormally.

The cover 23 is provided with a second gas-penetrable opening 30, which is in communication with the accommodating space and the external medium. In this embodiment, connected to the second gas- penetrable opening 30, gas at a front side of the fuel particulate filter in the exhaust system of the vehicle driven by the internal combustion engine.

An insert 31 is inserted in the through-hole 24 of the substrate 21; the insert 31 is formed of epoxy resin. The insert 31 comprises a first gas-penetrable opening 32, which is in communication with the first space 25 and the second face 212 of the substrate 21. The first gas-penetrable opening 32 is arranged to face the pressure sensing element 22. The width of the insert 31 in a direction perpendicular to the through-hole 24 is 2 - 4 times the diameter of the first gas-penetrable opening 32. In this embodiment, an external medium located in the first space 25 and connected to the first gas-penetrable opening 32 is a gas at a rear side of the fuel particulate filter in the exhaust system of the vehicle driven by the internal combustion engine.

The insert 31 is disposed on the substrate 21, such that the conditions of the substrate 21 at an edge of the through-hole 24 are changed, achieving a firmer surface texture and/or ceramic phase of the substrate 21, enhancing the robustness of acidic operation of the substrate 21 in the exhaust system of the vehicle driven by the internal combustion engine, lowering the fault rate of the MEMS differential pressure sensor 20, and extending the service life of the MEMS differential pressure sensor 20.

Other variants

Those skilled in the art should understand that although the cover 23 is disposed on the first face 211 of the substrate 21 in the embodiment above. The cover 23 is arranged around the pressure sensing element 22, and forms an accommodating space, i. e. the second space 26, between itself and the substrate 21. The pressure sensing element 22 is located in the accommodating space. The gel filler 29 is packed in the accommodating space. However, the present utility model is not limited to this; in other embodiments of the present utility model, the cover 23 is arranged around the pressure sensing element 22 and forms the second space 26 between itself and the substrate 21, and it is also possible to arrange a sidewall around the pressure sensing element 22, with an

accommodating space being formed between the sidewall and the substrate 21. The gel filler 29 is packed in the accommodating space, covering the pressure sensing element 22.

Those skilled in the art should understand that although, in the embodiment above, the substrate 21 also has the electrically conductive element 27 disposed on the first face, the electrically conductive element 27 is electrically connected to the pressure sensing element 22 via the conductive wire 28. The gel filler 29 is packed in the accommodating space, and covers the electrically conductive element 27. However, the present utility model is not limited to this; in other embodiments of the present utility model, the cover 23 further comprises a separate cavity for accommodating the electrically conductive element. The cavity is separate from the accommodating space, so as to isolate the electrically conductive element 27 from the acid environment of exhaust gas. In this case, there is no need for the gel filler 29 to cover the electrically conductive element 27.

Compared with the prior art, the sensor apparatus of the present utility model has the insert comprising the gas-penetrable opening on the substrate, with the insert being inserted in the through-hole of the substrate; this can increase the robustness, in terms of resisting the harsh operating environment of the sensor apparatus, of the substrate in the vicinity of the through- hole. This lowers the probability of a fault occurring in the sensor apparatus comprising the substrate having the through-hole, such as a MEMS differential pressure sensor or a MEMS liquid level sensor, and extends the service life of the sensor apparatus.

The above description of the content disclosed herein is provided to enable any person of ordinary skill in the art to realize or use the content disclosed herein. To a person of ordinary skill in the art, various amendments made to the content disclosed herein are obvious, and general principles defined herein could be applied to other variants without departing from the scope of protection of the content disclosed herein. Thus, the content disclosed herein is not restricted to the examples and designs described herein, but is consistent with the broadest scope conforming to the principles and novel features disclosed herein.

Claims

C l a i m s

1. A sensor apparatus, characterized in that the sensor

apparatus comprises: a substrate, comprising a first face and a second face opposite each other, and being provided with a through-hole in communication with the first face and the second face; an insert, inserted in the through-hole and comprising a first gas-penetrable opening; and a sensing element, mounted in a sealed manner on the first face of the substrate, with a first space and a second space being formed at two sides of the sensing element, the first space and the second space being isolated from one another in a gas-impermeable fashion, and the first gas- penetrable opening being in communication with the first space and the second face.

2. The sensor apparatus as claimed in claim 1, characterized in that the sensor apparatus further comprises a cover mounted on the first face of the substrate, with an accommodating space being formed between the cover and the substrate, and the sensing element being located in the accommodating space.

3. The sensor apparatus as claimed in claim 2, characterized in that the second space is located between the cover and the sensing element, and the cover is provided with a second gas- penetrable opening in communication with the second space.

4. The sensor apparatus as claimed in claim 1, characterized in that the sensor apparatus further comprises a gel filler, which at least partially fills the second space; the gel filler covers the sensing element.

5. The sensor apparatus as claimed in claim 4, characterized in that the gel filler is a liquid fluoroelastomer.

6. The sensor apparatus as claimed in claim 1, characterized in that the insert is formed of epoxy resin.

7. The sensor apparatus as claimed in claim 1, characterized in that the width of the insert in a direction perpendicular to the through-hole is 2 - 4 times the diameter of the first gas-penetrable opening.

8. The sensor apparatus as claimed in claim 1, characterized in that the substrate is a ceramic circuit board, having an electrically conductive element which is disposed on the first face and electrically connected to the sensing element.

9. The sensor apparatus as claimed in any one of claims 1 - 8, characterized in that the sensing element is a MEMS

differential pressure sensing element.

10. The sensor apparatus as claimed in any one of claims 1 - 8, characterized in that the sensing element is a MEMS liquid level sensing element.