High-temperature-resistant pressure sensor and manufacturing method thereof

Abstract

The invention relates to the technical field of pressure sensors, in particular to a high-temperature-resistant pressure sensor and a manufacturing method thereof, and the high-temperature-resistant pressure sensor comprises a shell which is provided with a mounting groove at one end and a channel communicated with the groove bottom of the mounting groove at the other end; the pressure sensing element is arranged in the mounting groove and is bonded and sealed with the groove bottom of the mounting groove through an adhesive; a circuit board; the circuit board is arranged on the connector and is electrically connected with the connector; interfaces at the two ends of the wire harness are electrically connected with the pressure sensing element and the circuit board respectively. According to the high-temperature-resistant pressure sensor and the manufacturing method thereof, the structure of the pressure sensor is changed, and the harsh high-temperature requirement can be met.

Description

Technical Field

[0001] The present invention relates to the field of pressure sensors, and more particularly to a high temperature resistant pressure sensor and a manufacturing method thereof. Background Art

[0002] Sensor technology is one of the important technologies of modern measurement and automation systems. From production process control to modern technological life, almost every technology is inseparable from sensors. Among them, ceramic capacitive pressure sensor is a commonly used type of pressure sensor with a wide pressure range and a wide range of applications. It is widely used in automobiles, home appliances, industry and other fields. The basic structure of products with different pressure ranges is similar. It is mainly composed of pressure-sensitive elements, circuit boards, electrical connectors, metal shells, etc. welded and riveted. The production process is similar, mainly including: welding-preassembly-riveting-stress relief-calibration-glue coating-functional testing-helium inspection. The seal between the pressure-sensitive element and the metal shell is mainly made of sealing rings. Due to the constraints of the materials of seals and electronic components, the operating temperature of ceramic capacitive pressure sensors cannot exceed 150°C. In an environment exceeding 150°C, there is a risk of sealing failure and product performance failure.

[0003] The existing ceramic capacitive pressure sensors mainly solve the problem of using in high temperature environments by improving the materials. For example, a capacitive pressure sensor disclosed in the invention patent with publication number CN 116519174A uses polymer precursor ceramics as the sensor electrode substrate, uses a liquid precursor with low viscosity and good fluidity to cast a template and then photocures to prepare a micrometer-level array column structure, realizes the integrated molding of the micrometer-level array column structure and the substrate, and gives full play to the excellent anti-oxidation, thermal shock resistance and creep resistance of polymer precursor ceramics, so that it can work in high temperature extreme environments. For another example, the invention patent with publication number CN109678519A discloses a high-temperature pressure sensor based on polymer precursor ceramics. The piezoresistive properties of polymer precursor ceramics are used to prepare a piezoresistive pressure sensor, and the sensor has a high operating temperature and a long service life. Although the above-mentioned ceramic capacitive pressure sensor can solve the problem of using in high temperature environments, its structure is complex, the processing difficulty is large, and the material cost will also increase. At the same time, it also needs to go through pre-assembly, riveting and other processes during production, which affects the assembly efficiency. Taking into account the material cost and processing efficiency, the high temperature resistant ceramic capacitive pressure sensor is ultimately expensive. Summary of the invention

[0004] The object of the present invention is to provide a high temperature resistant pressure sensor and a manufacturing method thereof in view of the above problems, and to change the structure of the pressure sensor so as to meet the stringent high temperature requirements.

[0005] In order to achieve these purposes and other advantages according to the present invention, a high temperature resistant pressure sensor is provided, comprising:

[0006] A housing having a mounting groove at one end and a channel communicating with the bottom of the mounting groove at the other end;

[0007] A pressure sensing element is disposed in the installation groove and is bonded and sealed to the bottom of the installation groove by an adhesive;

[0008] Circuit boards;

[0009] A connector, the circuit board being arranged on the connector and electrically connected thereto;

[0010] The wiring harness has interfaces at both ends electrically connected to the pressure sensing element and the circuit board respectively.

[0011] The beneficial effects of the present invention are:

[0012] In the present invention, the pressure sensing element and the shell are connected by a high-temperature resistant adhesive, the shell is made of metal, and the pressure sensing element is made of ceramic material, and both can be used normally under high temperature conditions. A seal is formed between the pressure sensing element and the shell, which can withstand high temperature and high pressure without failure, and can still be used normally in a high temperature environment exceeding 150°C. The channel on the shell is connected to the sensing end of the pressure sensing element, and the external medium enters the shell through the channel and directly acts on the sensing end of the pressure sensing element. The pressure sensing element can use an existing ceramic pressure sensor. The pressure sensing element is connected to the circuit board through a wiring harness, and the circuit board is electrically connected to the external client through a connector, receives the pressure signal sent by the pressure sensing element, and sends it to the external client. By arranging a wiring harness between the pressure sensing element and the circuit board, the distance between the circuit board and the pressure sensing element is increased by the wiring harness, so that electronic components such as the circuit board and the connector can be kept away from the high temperature area, thereby avoiding the influence of the high temperature environment, so that the pressure signal can be transmitted normally. In addition, the length of the wiring harness can be determined according to actual needs, and high temperature resistant pressure sensors with different wiring harness lengths are used according to different usage environments to enhance the applicability of high temperature resistant pressure sensors.

[0013] On the basis of the above technical solution, the present invention can also be improved as follows:

[0014] Furthermore, in the high temperature resistant pressure sensor, a metal coating is printed on the pressure sensing element, and the metal coating is melted after high temperature sintering to form the adhesive;

[0015] The beneficial effect of adopting the above further scheme is: in this further scheme, the metal coating is used as an adhesive. After the metal coating is melted, the pressure sensing element and the bottom of the installation groove are sintered together by the metal coating, the pressure sensing element and the housing are fixed and sealed, and the seal can be maintained at a high temperature of >150°C. Specifically, firstly, a molybdenum-manganese layer is applied to the pressure sensing element for sintering, and the molybdenum-manganese layer is sintered at a high temperature in a reducing atmosphere to form a metal layer on the surface of the ceramic, and then nickel is plated on the formed metal layer, and the metallized ceramic and the Kovar alloy are welded, and the welding material is a silver-copper welding sheet. The pores in the formed aluminum-manganese metallization layer are filled with glass phase and nickel. The infiltration and mutual diffusion of these substances form a firm vacuum sealing layer with excellent sealing effect, so that the pressure sensing element and the housing can be sealed and connected, and the connection structure has excellent temperature resistance and can ensure the sealing effect at a temperature of 600-800°C.

[0016] Furthermore, in the high temperature resistant pressure sensor, the pressure sensing element is composed of a substrate and a sensing sheet connected together, the substrate is electrically connected to one end of the wiring harness, and the sensing sheet is fixedly connected to the bottom of the mounting slot.

[0017] The beneficial effect of adopting the above further solution is: in this further solution, the substrate and the sensor chip are fixed by glass glue, and a layer of metal coating is coated on the sensor chip.

[0018] Furthermore, in the high temperature resistant pressure sensor, one end of the sensing sheet away from the substrate is concave, and the concave portion faces the channel.

[0019] The beneficial effect of adopting the above further scheme is: in this further scheme, the middle part of the end of the sensing sheet away from the substrate is concave, forming a concave surface, and the middle part of the concave surface is thinner, which can sense the change of pressure and produce deformation to transmit the pressure signal. A layer of metal coating is applied to the concave surface, and it contacts the bottom of the positioning groove on the shell. Under high temperature conditions, the metal coating melts, so that the concave surface of the sensing sheet and the bottom of the positioning groove of the shell are sintered together, fixing the pressure sensing element and the shell and forming a seal, and the seal can be kept intact under high temperature conditions of >150°C.

[0020] Furthermore, in the high temperature resistant pressure sensor, an interface at one end of the wiring harness, the housing and the pressure sensing element are sealed by potting glue.

[0021] The beneficial effect of adopting the above further scheme is: in this further scheme, the positioning groove is filled with potting glue, and the potting glue has good fluidity during the filling process, and can fill all the gaps in the positioning groove. After the potting glue fills the shell, it is cured under high temperature conditions. The cured potting glue has sufficient strength and temperature resistance, which can improve the stability of the product and make the product suitable for various harsh environments. The interface at one end of the wire harness, the shell and the pressure sensing element are fixed together by potting glue, and one end of the shell is wrapped to prevent external media from corroding the pressure sensing element in the positioning groove of the shell and the interface of the wire harness, thereby ensuring the stability of the product. At the same time, it can be highly waterproof, and external water and other media will not overflow into the product.

[0022] Furthermore, in the high temperature resistant pressure sensor, the interface at the other end of the wiring harness, the connector and the circuit board are sealed by potting glue.

[0023] The beneficial effect of adopting the above further scheme is: in this further scheme, after the circuit board is welded in the connector, the opening of the connector is filled with potting glue. The potting glue has good fluidity during the filling process and can fill all the gaps in the connector opening. After the potting glue fills the connector opening, it is cured under high temperature conditions. The cured potting glue has sufficient strength and temperature resistance, which can improve the stability of the product and make the product suitable for various harsh environments. The other end interface of the wiring harness, the connector and the circuit board are fixed together by potting glue, and the opening of the connector is wrapped to prevent external media from corroding the circuit board in the connector and the interface of the wiring harness, thereby ensuring the stability of the product. At the same time, it can be highly waterproof, and external media such as water will not seep into the interior of the product.

[0024] Furthermore, in the high temperature resistant pressure sensor, the electronic components on the circuit board are distributed on both sides thereof.

[0025] The beneficial effect of adopting the above further solution is: in this further solution, the electronic components on the circuit board are distributed on both sides thereof, which can reduce the size of the circuit board, thereby reducing the size of the connector and optimizing the structure of the connector.

[0026] The present invention also provides a method for manufacturing the high temperature resistant pressure sensor as described in any one of the above, comprising the following steps:

[0027] S1, printing a metal coating on the sensing end of the pressure sensing element, placing it in a mounting groove on the housing, and then sintering it under high temperature conditions, wherein the metal coating melts and acts as the adhesive to bond the pressure sensing element to the housing;

[0028] S2, welding the circuit board to the connector;

[0029] S3. Electrically connect the interfaces at both ends of the wiring harness to the pressure sensing element and the circuit board respectively, and seal the interface at one end of the wiring harness, the shell and the pressure sensing element with potting glue, and seal the interface at the other end of the wiring harness, the connector and the circuit board with potting glue.

[0030] The beneficial effect of adopting the above further scheme is: in this further scheme, in the manufacturing process of the high temperature resistant pressure sensor, it is only necessary to complete the high temperature sintering between the pressure sensing element and the shell, the welding of the circuit board and the connector, the connection of the wiring harness and the sealing of the potting glue. Compared with the traditional pre-assembly, riveting and other processes, the production process is greatly shortened, thereby reducing the assembly time of the high temperature resistant pressure sensor and improving the manufacturing efficiency of the high temperature resistant pressure sensor.

[0031] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 An exploded diagram of the high temperature resistant pressure sensor of the present invention;

[0033] Figure 2 is a cross-sectional view of the high temperature resistant pressure sensor of the present invention;

[0034] Figure 3 It is a structural schematic diagram of the pressure sensing element of the present invention;

[0035] Figure 4 The figure is a schematic diagram of the structure of the circuit board described in the present invention.

[0036] The reference numerals are as follows: 1-housing; 2-pressure sensing element; 3-wiring harness; 4-circuit board; 5-connector; 6-potting glue; 7-substrate; 8-sensing sheet. DETAILED DESCRIPTION

[0037] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0038] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials are commercially available unless otherwise specified; in the description of the present invention, the terms "lateral", "longitudinal", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0039] like Figure 1-Figure 2 As shown, an embodiment of the present invention provides a high temperature resistant pressure sensor, including a housing 1, a pressure sensing element 2, a circuit board 4, a connector 5 and other components. One end of the housing 1 is an open cavity, which forms a mounting groove matching the pressure sensing element 2, and the pressure sensing element 2 is placed in the mounting groove. The other end of the housing 1 is a tubular structure, which is tightly matched with the external threaded connection to form a fixed, and the inside of the tubular structure forms a channel for the medium to flow. The pressure sensing element is composed of a substrate 7 and a sensing sheet 8. The sensing sheet 8 is a "concave" structure. The middle part of the sensing sheet 8 is thinner, and can sense the change of pressure and produce deformation to transmit the pressure signal. The circuit board 4 is placed in the connector 5. Three small round holes are designed on the circuit board 4, corresponding to the positions of the three PIN pins on the connector 5. The three PIN pins are electrically connected to the circuit on the circuit board 4 by soldering. At the same time, the circuit board 4 is also coupled to one end of the wire 3 by soldering, and the other end of the wire 3 is coupled to the pressure sensing element 2 by soldering. The potting glue 6 fills the opening cavity of the shell 1 and the welding end cavity of the connector 5, and wraps the internal parts of the shell 1 and the connector 5 to prevent the external medium from corroding the parts and ensure the stability of the product. At the same time, it can be highly waterproof, and external water and other media will not overflow into the interior of the product. The potting glue 6 has good fluidity during the filling process and can fill all gaps in the opening cavity of the shell 1 and the connector 5. After the potting glue fills the opening inner cavity of the shell 1 and the connector 5, it is cured under high temperature conditions. The cured potting glue 6 has sufficient strength and temperature resistance, which can improve the stability of the product and make the product suitable for various harsh environments.

[0040] Preferably, as another embodiment of the present invention, Figure 2-3 As shown, in Figure 1-Figure 2 Based on the embodiment shown, it also includes:

[0041] The pressure sensing element 2 is composed of two parts: a substrate 7 and a sensing sheet 8. Three holes are designed on the substrate 7, and three metal PIN needles are installed on the three holes. The PIN needles are fixed to the substrate 7 by conductive epoxy glue. The sensing sheet 8 is a "concave" structure. The large plane is fixed to the substrate 7 by glass glue. A layer of metal is coated on the surface of one end of the concave surface. The concave end of the sensing sheet contacts the inner end surface of the opening cavity of the shell 1. Under high temperature conditions, the metal coating melts, so that the concave end of the sensing sheet 8 is sintered together with the inner end surface of the opening cavity of the shell 1, and the pressure sensing element 2 and the shell 1 are fixed and sealed. The seal can be maintained under high temperature conditions (>150°C) without failure. The thinner position in the middle of the concave end of the sensing sheet 8 will deform under the action of pressure, thereby transmitting the pressure signal.

[0042] Preferably, as another embodiment of the present invention, Figure 4 As shown, in Figure 1-Figure 2 On the basis of the embodiment shown, it also includes: the circuit board 4 is a cylindrical structure, three through holes are designed to cooperate with the PIN pins of the connector 5, the circuit board 4 is designed with a buckle for easy soldering with the wire 3 to prevent the solder joint from being too large and affecting the circuit and other electronic components on the circuit board, the circuit board 4 has a certain structural strength, and there is no risk of deformation and offset after being fixed during the assembly process, thereby improving the assembly stability. The circuit board 4 is designed as a double-layer structure, and electronic components are assembled on both the front and back sides, which greatly reduces the size of the circuit board 4 and can be directly installed inside the opening of the connector 5.

[0043] Preferably, as another embodiment of the present invention, Figure 1-Figure 4 As shown, in Figure 1-Figure 2 On the basis of the illustrated embodiment, the high temperature resistant pressure sensor is divided into two parts, one part is composed of a shell 1, a pressure sensing element 2 and a potting compound 6, this part can be used under high temperature conditions (>150°C), the shell 1 is made of metal, and the pressure sensing element 2 is made of ceramic material, both of which can be used under high temperature conditions without being affected, and the other part is a circuit board 4, a connector 5 and a potting compound 6, this part has electronic components and other parts that are easily affected by temperature, and by changing the length of the wiring harness 3, it can be away from the high temperature area without being affected, and the pressure signal can be transmitted normally.

[0044] An embodiment of the present invention further provides a method for manufacturing the high temperature resistant pressure sensor as described in any one of the above, comprising the following steps:

[0045] S1, printing a metal coating on the sensing end of the pressure sensing element, placing it in a mounting groove on the housing, and then sintering it under high temperature conditions, wherein the metal coating melts and acts as the adhesive to bond the pressure sensing element to the housing;

[0046] The sintering specifically includes the following steps: firstly, a molybdenum-manganese layer is applied to the pressure sensing element for sintering, the molybdenum-manganese layer is sintered at high temperature in a reducing atmosphere to form a metal layer on the surface of the ceramic, and then nickel is plated on the formed metal layer, the metallized ceramic and the Kovar alloy are welded, the welding material is a silver-copper welding sheet, and the pores in the formed aluminum-manganese metallization layer are filled with glass phase and nickel, and the penetration and mutual diffusion of these substances form a firm vacuum sealing layer with excellent sealing effect;

[0047] S2, welding the circuit board to the connector;

[0048] S3. Electrically connect the interfaces at both ends of the wiring harness to the pressure sensing element and the circuit board respectively, and seal the interface at one end of the wiring harness, the shell and the pressure sensing element with potting glue, and seal the interface at the other end of the wiring harness, the connector and the circuit board with potting glue.

[0049] In the above embodiment, during the manufacturing process of the high temperature resistant pressure sensor, high temperature sintering is completed in advance between the pressure sensing element and the shell, which mainly includes welding-glue pouring-calibration-functional testing-helium inspection and other processes. Compared with the production process of traditional products: welding-preassembly-riveting-stress relief-calibration-glue coating-functional testing-helium inspection, the present embodiment reduces the process of "preassembly-riveting-stress relief-glue coating" and only adds the process of "glue pouring", which greatly reduces the production process as a whole, thereby reducing the assembly time of the high temperature resistant pressure sensor and improving the manufacturing efficiency of the high temperature resistant pressure sensor.

[0050] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A high temperature resistant pressure sensor, characterized in that: include: A housing having a mounting groove at one end and a passage communicating with the bottom of the mounting groove at the other end; A pressure sensing element is disposed in the installation groove and is bonded and sealed to the bottom of the installation groove by an adhesive; Circuit boards; A connector, the circuit board is arranged on the connector and is electrically connected thereto; The wiring harness has interfaces at both ends electrically connected to the pressure sensing element and the circuit board respectively.

2. A high temperature resistant pressure sensor as claimed in claim 1, characterized in that: A metal coating is printed on the pressure sensing element, and the metal coating is melted after high-temperature sintering to form the adhesive.

3. A high temperature resistant pressure sensor as claimed in claim 2, characterized in that: The pressure sensing element is composed of a substrate and a sensing sheet connected together, the substrate is electrically connected to one end of the wiring harness, and the sensing sheet is fixedly connected to the bottom of the installation slot.

4. A high temperature resistant pressure sensor as claimed in claim 4, characterized in that: One end of the sensing sheet away from the substrate is concave, and the concave portion faces the channel.

5. A high temperature resistant pressure sensor as claimed in claim 1, characterized in that: An interface at one end of the wiring harness, the housing and the pressure sensing element are sealed by potting glue.

6. A high temperature resistant pressure sensor as claimed in claim 5, characterized in that: The other end interface of the wiring harness, the connector and the circuit board are sealed by potting glue.

7. A high temperature resistant pressure sensor as claimed in claim 1, characterized in that: The electronic components on the circuit board are distributed on both sides thereof.

8. A method for manufacturing a high temperature resistant pressure sensor according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, printing a metal coating on the sensing end of the pressure sensing element, placing it in a mounting groove on the housing, and then sintering it under high temperature conditions, wherein the metal coating melts and acts as the adhesive to bond the pressure sensing element to the housing; S2, welding the circuit board to the connector; S3. Electrically connect the interfaces at both ends of the wiring harness to the pressure sensing element and the circuit board respectively, and seal the interface at one end of the wiring harness, the shell and the pressure sensing element with potting glue, and seal the interface at the other end of the wiring harness, the connector and the circuit board with potting glue.

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