Vacuum sealed pressure sensor and welding process thereof

Abstract

The invention relates to a vacuum sealed pressure sensor and a welding process thereof, and relates to the technical field of pressure sensors, the pressure sensor comprises a sensor body, the sensor body is sleeved with a supporting ring, a substrate is fixed on the end face of the supporting ring, a plurality of conducting rods are fixed and electrically connected to a PCB, and the substrate is provided with welding holes for the conducting rods to penetrate through. The conducting rod and the substrate are fixed through welding, the supporting ring and the sensor body are fixed through welding, and the interior of the supporting ring is a vacuum environment. The sensor body is clamped on an electric turntable in a vacuum box, and the interior of the vacuum box is vacuumized; and welding the contact position of the conducting rod and the substrate. The conducting rod serves as the final signal leading-out end of the pressure sensor, other welding modes except tin soldering can be adopted, and the conducting rod is not prone to fusing in the welding process; and the same metal is adopted for welding, so that the welding stability between the conducting rod and the substrate can be ensured to the greatest extent, and the advantages of strong sealing and long service life are achieved.

Description

Technical Field

[0001] The present application relates to the technical field of pressure sensors, and in particular to a vacuum-sealed pressure sensor and its welding process. Background Art

[0002] MSG pressure sensors using micro-melted silicon strain gauge (MSG) technology have been widely used in various fields such as vehicle braking systems, vehicle stability control systems, fuel pressure monitoring systems, and transmission systems. MSG pressure sensors generally include a silicon strain gauge element, which is glass-bonded to a metal diaphragm of a pressure port body to form a sensitive element. The silicon strain gauges form a Wheatstone bridge. According to the characteristics that the resistance value of the silicon strain gauge decreases under pressure and increases under tension, after power is applied to the Wheatstone bridge, the node voltage signal changes with the deformation of the metal diaphragm, and this signal is then calibrated to a linear output proportional to the pressure applied on the metal diaphragm.

[0003] Sensors made using the MSG technology solution belong to gauge pressure sensors. In the initial stage of the development of MSG pressure sensors, they were mainly used in the field of high-pressure sensors. The influence of the external environmental pressure on the output accuracy of high-pressure products is minimal, and generally, there is no distinction between gauge pressure and absolute pressure. Considering the obvious advantages of MSG technology in terms of reliability and accuracy, MSG technology has gradually developed towards the medium-pressure field. To adapt to the application requirements, in addition to the existing gauge pressure output of MSG, a corresponding MSG absolute pressure output method needs to be developed to better achieve full-field coverage.

[0004] Regarding the above related technologies, if a pressure sensor is to output a signal in the form of absolute pressure, a vacuum environment needs to be maintained inside the pressure sensor, and the vacuum degree needs to reach medium vacuum. However, forming a vacuum environment inside the pressure sensor causes difficulties in sealing and welding. If an elastic seal is used, with the increase in the use time, the seal is prone to aging and falling off, resulting in air leakage; if welding is used, the thinner lead wires can only be fixed to the housing by soldering. However, as tin is a different metal material, its firmness cannot be guaranteed, and there is room for improvement. Summary of the Invention

[0005] The present application provides a vacuum-sealed pressure sensor and its welding process, which can form a highly sealed vacuum chamber inside the pressure sensor, and the welding is firm and reliable.

[0006] A vacuum-sealed pressure sensor provided by the present application adopts the following technical solution:

[0007] A vacuum-sealed pressure sensor includes a sensor body. A support base is fixed on the sensor body, and a PCB board is mounted on the support base. A plurality of wires are electrically connected between the sensor body and the PCB board. A support ring is sleeved outside the sensor body, and a substrate is fixed on the end face of the support ring. A plurality of conductive rods are fixed and electrically connected on the PCB board. The substrate is provided with welding holes for the conductive rods to pass through, and the conductive rods are fixed to the substrate by welding. The support ring is fixed to the sensor body by welding, and the inside of the support ring is a vacuum environment.

[0008] By adopting the above technical solution, using the conductive rod as the final signal lead-out end of the pressure sensor, compared with traditional leads and pins, the diameter of the conductive rod is significantly increased, and it is not easily bent and deformed, and the surface shape is regular. Therefore, other welding methods except soldering can be used, and the conductive rod is not easily melted during the welding process.

[0009] Optionally, the support ring and the substrate are connected and fixed by SMT process and sealed, and the support ring and the substrate form a support assembly.

[0010] By adopting the above technical solution, through the SMT process, a reliable seal is formed between the support ring and the substrate.

[0011] Optionally, the substrate includes a plate body made of insulating material and a conductor made of metal material. The welding holes are located in the conductor, and the conductor is connected and fixed to the plate body by SMT process.

[0012] By adopting the above technical solution, through the SMT process, a reliable seal is formed between the conductor and the plate body. The plate body prevents short circuits caused by the electrical connection of each conductive rod, and the conductor is used to complete the welding with the conductive rod.

[0013] Optionally, the conductive rod and the conductor are made of the same metal, and the conductive rod is fixed to the conductor by welding.

[0014] By adopting the above technical solution, the conductive rod and the conductor are combined by welding.

[0015] Optionally, the conductive rod includes an outer rod connected to the substrate and an inner rod connected to the PCB board. The outer rod and the inner rod are connected by end insertion, and the outer rod is in interference fit with the welding hole.

[0016] By adopting the above technical solution, the detachable outer rod and inner rod structure is used to adapt to resistance welding. When performing resistance welding, since the outer rod and the inner rod are separated, the current will not pass through the PCB board and the sensor body, avoiding damage to the sensor. Through the interference fit between the outer rod and the welding hole, when the support ring and the sensor body are separated, the substrate will drive the outer rod to move, making the outer rod and the inner rod reliably separated.

[0017] In a second aspect, the present application provides a welding process for a vacuum-sealed pressure sensor, adopting the following technical solutions:

[0018] A welding process for a vacuum-sealed pressure sensor, used for manufacturing the above-mentioned vacuum-sealed pressure sensor, includes the following steps:

[0019] Step S1: The support ring and the substrate are connected and fixed by SMT process and sealed to form a component, and the sensor body, the support base, the PCB board and the conductive rod are assembled into a component;

[0020] Step S2: The support ring is sleeved and installed outside the sensor body, and is installed in place through the step, and at the same time, the conductive rod passes through the welding hole to form positioning;

[0021] Step S3: The sensor body is clamped on the electric turntable in the vacuum chamber, and the inside of the vacuum chamber is evacuated;

[0022] Step S4: Weld the contact position between the conductive rod and the substrate;

[0023] Step S5: Laser-weld the contact position between the support ring and the sensor body, and the electric turntable drives the product to rotate during welding;

[0024] Step S6: Remove the welded product from the vacuum chamber.

[0025] By adopting the above technical solutions, a vacuum environment is formed inside the product after welding. Welding in a vacuum environment can improve the quality of welding and laser welding; the electric turntable drives the product to rotate, which is convenient for the welding manipulator to perform welding operations.

[0026] Optionally, laser welding is used in step S4, and the welding is performed by a welding manipulator.

[0027] By adopting the above technical solutions, using a welding manipulator can achieve automatic laser welding.

[0028] Optionally, resistance welding is used in step S4, and the welding is performed by a resistance welding manipulator.

[0029] By adopting the above technical solutions, resistance welding has the advantages of short heating time, concentrated heat, fast welding speed, and does not require welding wire, and there is no noise and harmful gas generation during the welding process. By resistance welding, the metal material filled at the weld is generated by melting, so the conductive rod, the conductor and their welding positions are also of the same metal.

[0030] Optionally, an auxiliary manipulator is provided inside the vacuum chamber. In step S4, the auxiliary manipulator pulls up the support ring to separate the outer rod from the inner rod. Then, the resistance welding manipulator welds the contact position between the outer rod and the substrate. After welding is completed, the auxiliary manipulator moves down the support ring to reset it, so that the outer rod and the inner rod are inserted into each other through the ends.

[0031] By adopting the above technical solution, during resistance welding, the auxiliary manipulator pulls up the support ring to separate the outer rod from the inner rod. Therefore, the welding current will not pass through the PCB board and the sensor body, and the welding voltage will not be applied to the PCB board and the sensor body, avoiding damage to the sensor.

[0032] In summary, the present application includes at least one of the following beneficial technical effects:

[0033] 1. By using the conductive rod as the final signal lead-out end of the pressure sensor, welding methods other than soldering can be used, and the conductive rod is not easily melted during the welding process;

[0034] 2. Other types of metals are avoided from being introduced during the welding process, which can ensure the welding stability between the conductive rod and the substrate to the greatest extent. Under the condition of a large pressure difference between the inside and outside of the support ring, it also has the advantages of strong sealing and long life. Description of the Drawings

[0035] Figure 1 is a sectional view of a vacuum-sealed pressure sensor in Embodiment 1;

[0036] Figure 2 is a schematic diagram of the welding process of a vacuum-sealed pressure sensor in Embodiment 2;

[0037] Figure 3 is a sectional view of Embodiment 3;

[0038] Figure 4 is a schematic diagram of Embodiment 4.

[0039] Description of the reference numerals: 1. Sensor body; 11. Support seat; 12. PCB board; 13. Lead wire; 2. Support ring; 3. Substrate; 4. Conductive rod; 30. Welding hole; 31. Plate body; 32. Conductor; 5. Vacuum chamber; 51. Electric turntable; 52. Welding manipulator; 41. Outer rod; 42. Inner rod; 53. Resistance welding manipulator; 54. Auxiliary manipulator. Detailed Description of the Embodiments

[0040] The following further describes the present application in detail with reference to the drawings.

[0041] Embodiment 1:

[0042] Refer to Figure 1, this embodiment discloses a vacuum-sealed pressure sensor, which includes a sensor body 1. A support base 11 is fixed on the sensor body 1, and a PCB board 12 is installed on the support base 11. A plurality of wires 13 are electrically connected between the sensor body 1 and the PCB board 12. The power supply of the sensor body 1 comes from the PCB board 12, and the signals of the sensor body 1 are preprocessed by the PCB board 12.

[0043] A support ring 2 is sleeved outside the sensor body 1. A substrate 3 is fixed on the end face of the support ring 2. A plurality of conductive rods 4 are fixed and electrically connected to the PCB board 12, and the diameter of the conductive rods 4 is 1.5 - 2 mm. The substrate 3 is provided with welding holes 30 for the conductive rods 4 to pass through. The conductive rods 4 are fixed to the substrate 3 by welding. The support ring 2 is fixed to the sensor body 1 by welding. The inside of the support ring 2 is a vacuum environment, which is obtained by welding and sealing in a vacuum container.

[0044] The substrate 3 includes a plate body 31 made of an insulating material and a conductor 32 made of a metal material. The plate body 31 is made of a hard material for PCB, ensuring airtightness on both sides. The conductive rods 4 and the conductor 32 are made of the same metal, and the conductive rods 4 are fixed to the conductor 32 by welding. The welding holes 30 are located inside the conductor 32, that is, the positions where the conductive rods 4 pass through the substrate 3 are inside the conductor 32. The conductor 32 is connected and fixed to the plate body 31 by SMT process and forms a reliable seal. The support ring 2 and the substrate 3 are connected and fixed and sealed by SMT process. The support ring 2 and the substrate 3 form a support assembly. SMT is the surface mount technology of electronic circuits, also known as surface mounting or surface installation technology. It is a circuit assembly technology that mounts surface mount components without pins or short leads on the surface of a printed circuit board and is welded and assembled by methods such as reflow soldering or dip soldering.

[0045] The implementation principle of a vacuum-sealed pressure sensor in this application embodiment is: using the conductive rods 4 as the final signal lead-out ends of the pressure sensor. Compared with traditional leads and pins, the conductive rods 4 have a significantly increased diameter, are not easily bent and deformed, and have a regular surface shape. Therefore, other welding methods besides soldering can be used, and the conductive rods 4 are not easily melted during the welding process. Other types of metals are avoided during the welding process, which can ensure the stability between the conductive rods 4 and the substrate 3 to the greatest extent. Under the condition of a large pressure difference between the inside and outside of the support ring 2, it also has the advantages of strong sealing and long life.

[0046] Embodiment Two:

[0047] A welding process for a vacuum-sealed pressure sensor, which is used to produce a vacuum-sealed pressure sensor in Embodiment One, includes the following steps:

[0048] Step S1: Pre-assembly. The support ring 2 and the substrate 3 are fixedly connected and sealed through the SMT process to form a component, which is a support assembly. The support assembly is a cylindrical structure with a sealed top and an open bottom; the sensor body 1, the support base 11, the PCB board 12, and the conductive rod 4 are assembled into a component.

[0049] Step S2: The support ring 2 is sleeved and installed outside the sensor body 1 and installed in place through the step, and at the same time, the conductive rod 4 passes through the welding hole 30 to form a positioning.

[0050] Step S3: Refer to Figure 2 , the sensor body 1 is clamped to the electric turntable 51 inside the vacuum chamber 5, and the inside of the vacuum chamber 5 is evacuated.

[0051] Step S4: Weld the contact position between the conductive rod 4 and the substrate 3.

[0052] In this embodiment, laser welding is used for welding, and a welding manipulator 52 is used for the operation. After welding one conductive rod 4, the electric turntable 51 is controlled to drive the product to rotate, and then another conductive rod 4 is welded to facilitate the operation of the welding manipulator 52.

[0053] Step S5: Laser weld the contact position between the support ring 2 and the sensor body 1. During welding, the electric turntable 51 drives the product to rotate, and the laser welding is completed by a laser welding manipulator.

[0054] Step S6: Remove the welded product from the vacuum chamber 5.

[0055] The process of this embodiment is used to adapt to the laser welding scenario. Welding in a vacuum environment can improve the quality of laser welding. After the product is welded, a vacuum environment can be maintained inside, other types of metals are avoided from being introduced during the welding process, and the welded and sealed positions are firm and highly reliable.

[0056] Embodiment Three:

[0057] Refer to Figure 3 , a vacuum-sealed pressure sensor. The difference between Embodiment Three and Embodiment One is that: the conductive rod 4 includes an outer rod 41 connected to the substrate 3 and an inner rod 42 connected to the PCB board 12. The outer rod 41 and the inner rod 42 are connected by end insertion, and the outer rod 41 has an interference fit with the welding hole 30.

[0058] The detachable outer rod 41 and inner rod 42 structure is used to adapt to resistance welding.

[0059] Embodiment Four:

[0060] A welding process for a vacuum-sealed pressure sensor, which is used to produce a vacuum-sealed pressure sensor in Embodiment Three. The difference between Embodiment Four and Embodiment Two is that: Refer toFigure 4 In step S4, resistance welding is used for welding, and a resistance welding manipulator 53 is used for the operation.

[0061] An auxiliary manipulator 54 is provided in the vacuum chamber 5. In step S4, the auxiliary manipulator 54 pulls up the support ring 2. Since the outer rod 41 is in interference fit with the welding hole 30, the outer rod 41 moves up together with the substrate 3, so that the outer rod 41 is separated from the inner rod 42. Then, the resistance welding manipulator 53 welds the contact position between the outer rod 41 and the substrate 3. Specifically, the two electrodes of the resistance welding manipulator 53 are respectively in contact with the outer rod 41 and the conductor 32. After welding is completed, the auxiliary manipulator 54 moves down the support ring 2 to reset it, so that the outer rod 41 and the inner rod 42 are inserted into each other through the ends.

[0062] When performing resistance welding, since the outer rod 41 is separated from the inner rod 42, the current will not pass through the PCB board 12 and the sensor body 1, avoiding damage to the sensor.

[0063] The process of this embodiment is used to implement resistance welding. Resistance welding has the advantages of short heating time, concentrated heat, fast welding speed, and does not require welding wire. There is no noise and harmful gas generation during the welding process. Through resistance welding, the metal material filled at the weld is generated by melting. Therefore, the conductive rod 4, the conductor 32 and their welding positions are also of the same metal, improving the welding stability compared with soldering.

[0064] The above are all the preferred embodiments of this application. The protection scope of this application is not limited by this. Therefore, all equivalent changes made according to the structure, shape, and principle of this application should be covered within the protection scope of this application.

Claims

1. A vacuum-sealed pressure sensor, comprising a sensor body (1), characterized in that: A support base (11) is fixed on the sensor body (1). A PCB board (12) is mounted on the support base (11). A plurality of wires (13) are electrically connected between the sensor body (1) and the PCB board (12). A support ring (2) is sleeved outside the sensor body (1). A substrate (3) is fixed on the end face of the support ring (2). A plurality of conductive rods (4) are fixed and electrically connected on the PCB board (12). The substrate (3) is provided with welding holes (30) for the conductive rods (4) to pass through. The conductive rods (4) and the substrate (3) are fixed by welding. The support ring (2) and the sensor body (1) are fixed by welding. The inside of the support ring (2) is a vacuum environment.

2. The vacuum-sealed pressure sensor according to claim 1, characterized in that: The support ring (2) and the substrate (3) are fixedly connected and sealed by SMT process, and the support ring (2) and the substrate (3) form a support assembly.

3. A vacuum-sealed pressure sensor according to claim 1, characterized in that: The substrate (3) includes a plate body (31) made of insulating material and a conductor (32) made of metal material. The welding holes (30) are located in the conductor (32). The conductor (32) and the plate body (31) are fixedly connected by SMT process.

4. A vacuum-sealed pressure sensor according to claim 3, characterized in that: The conductive rods (4) and the conductor (32) are made of the same metal, and the conductive rods (4) and the conductor (32) are fixed by welding.

5. A vacuum-sealed pressure sensor according to claim 1, wherein: The conductive rod (4) includes an outer rod (41) connected to the substrate (3) and an inner rod (42) connected to the PCB board (12). The outer rod (41) and the inner rod (42) are connected by end insertion, and the outer rod (41) is in interference fit with the welding hole (30).

6. A welding process for a vacuum-sealed pressure sensor, characterized in that: For manufacturing a vacuum-sealed pressure sensor according to any one of claims 1-5, the following steps are included: Step S1: The support ring (2) and the substrate (3) are fixedly connected and sealed by SMT process to form a component, and the sensor body (1), the support base (11), the PCB board (12) and the conductive rods (4) are assembled into a component; Step S2: The support ring (2) is sleeved and installed outside the sensor body (1) and installed in place by steps. At the same time, the conductive rods (4) pass through the welding holes (30) to form positioning; Step S3: The sensor body (1) is clamped on the electric turntable (51) inside the vacuum chamber (5), and the inside of the vacuum chamber (5) is evacuated; Step S4: Weld the contact position between the conductive rod (4) and the substrate (3); Step S5: Laser weld the contact position between the support ring (2) and the sensor body (1). When welding, the electric turntable (51) drives the product to rotate; Step S6: Remove the welded product from the vacuum chamber (5).

7. The soldering process of a vacuum-sealed pressure sensor according to claim 6, characterized in that: When performing step S4, laser welding is used for welding, and a welding manipulator (52) is used for the operation.

8. The welding process of a vacuum-sealed pressure sensor according to claim 6, characterized in that: When performing step S4, resistance welding is used for welding, and a resistance welding manipulator (53) is used for the operation.

9. The welding process of a vacuum-sealed pressure sensor according to claim 8, characterized in that: An auxiliary manipulator (54) is provided inside the vacuum chamber (5). At step S4, the auxiliary manipulator (54) pulls up the support ring (2) to separate the outer rod (41) from the inner rod (42). Then, the resistance welding manipulator (53) welds the contact position between the outer rod (41) and the substrate (3). After the welding is completed, the auxiliary manipulator (54) moves the support ring (2) downward to reset it, so that the outer rod (41) and the inner rod (42) are inserted into each other at the ends.

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