Capacitance vacuum gauge with ceramic-metal low-stress weld

Abstract

The application discloses a ceramic-metal low-stress welded capacitive vacuum gauge, which comprises a metal shell and a ceramic base connected to the metal shell, and a metal transition layer is arranged at the connecting interface of the ceramic base and the metal shell; the metal transition layer is a copper-nickel composite structure with a copper layer and a nickel layer, the nickel layer is connected with the ceramic base, and the copper layer is connected with the metal shell. A gradient layer with a gradually changing thermal expansion coefficient from the ceramic side to the metal shell side is constructed. The thermal performance of the nickel layer is relatively close to that of the ceramic base, which is beneficial to the interface combination; the copper layer is more matched with the metal shell, and the good plasticity of the copper layer can be used as stress buffering. In the welding heat cycle process, the metal transition layer can effectively absorb and disperse the thermal stress generated due to the uneven shrinkage of the base metals on both sides, so that the risk of ceramic cracking is reduced, and the low-leakage-rate weld is ensured.

Description

Technical Field

[0001] This invention relates to the field of capacitive vacuum gauge technology, and more particularly to a capacitive vacuum gauge with low-stress ceramic-metal welding. Background Technology

[0002] A capacitive vacuum gauge is a precision instrument that measures vacuum levels based on the principle of capacitance change, and it relates to the fields of pressure and vacuum measurement. In existing technologies (such as Chinese patent publication number CN101776502A), its core component typically includes a reference cavity that maintains an ultra-high vacuum, formed by welding a ceramic substrate to a metal shell. The ceramic substrate, due to its excellent insulation properties, low outgassing rate, and good dimensional stability, is widely used to support the internal electrodes; the metal shell provides mechanical support, electromagnetic shielding, and forms the external gas path interface. Therefore, achieving a high-strength, highly airtight, and long-term stable connection between the ceramic substrate and the metal shell is one of the keys to ensuring the measurement accuracy and reliability of the vacuum gauge.

[0003] The ceramic substrate and the metal shell are typically joined by high-temperature brazing or fusion welding. However, there is a significant difference in the coefficients of thermal expansion between the ceramic substrate and the metal shell. During welding, the huge heat input and the residual thermal stress caused by shrinkage mismatch during cooling can easily lead to microcracks or even direct cracking of the brittle ceramic near the weld. This structural damage not only directly weakens the connection strength but also becomes a channel for vacuum leakage, causing the vacuum level of the reference cavity to be unmaintained, thus making the vacuum gauge inaccurate or even completely malfunction. Summary of the Invention

[0004] In view of this, the present invention proposes a capacitive vacuum gauge with low-stress ceramic-metal welding, which aims to suppress welding stress caused by the mismatch of thermal expansion coefficients between ceramic and metal, avoid ceramic cracking, and achieve long service life and high reliability of the connection structure.

[0005] The technical solution of this invention is implemented as follows: A ceramic-metal low-stress welded capacitive vacuum gauge includes a metal shell and a ceramic substrate connected to the metal shell. A metal transition layer is provided at the interface between the ceramic substrate and the metal shell. The metal transition layer is a double-layer copper-nickel composite structure with a copper layer and a nickel layer. The nickel layer is in contact with the ceramic substrate, and the copper layer is in contact with the metal shell.

[0006] As a further optional solution, the surface of the ceramic substrate in contact with the metal transition layer is provided with a metallization layer.

[0007] As a further alternative, the metallization layer is directly bonded to the surface of the nickel layer of the metal transition layer.

[0008] As a further alternative, the metallization layer is made of nickel.

[0009] As a further alternative, the metal transition layer is an integral copper-nickel rolled composite strip.

[0010] As a further alternative, the metal transition layer consists only of a copper layer and a nickel layer, wherein the copper layer is a pure copper layer and the nickel layer is a pure nickel layer.

[0011] As a further optional solution, the ceramic substrate, the metal transition layer and the metal shell are brazed at low temperature with tin-silver-copper solder, without the use of titanium-based solder components during the brazing process.

[0012] As a further alternative, the metal casing may be made of Kovar alloy or austenitic stainless steel.

[0013] As a further optional solution, a fixed electrode is provided on the ceramic substrate, and the fixed electrode is electrically connected to an external circuit through an internal wire.

[0014] As a further optional solution, the internal wires are electrically connected to the fixed electrode by resistance spot welding.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: 1. Achieving a gradient match in the coefficient of thermal expansion, significantly reducing welding stress at its source: The copper-nickel composite structure of the metal transition layer constructs a physical buffer zone with a gradual change in performance between the ceramic substrate and the metal shell. The nickel layer, due to its relatively low coefficient of thermal expansion, is more compatible with the ceramic substrate side; the copper layer, due to its relatively high coefficient of thermal expansion, is closer to the metal shell side. This design creates a continuous gradient in the coefficient of thermal expansion, effectively absorbing and dispersing the interfacial shear stress and tensile stress caused by the inconsistent shrinkage of the materials on both sides during the welding thermal cycle. This fundamentally avoids stress concentration at the brittle ceramic substrate interface, significantly reducing the risk of cracking of the ceramic substrate.

[0016] 2. Utilizing the excellent plastic deformation capability of the copper layer to actively absorb and release residual stress: The copper layer possesses good ductility and plasticity. Under the action of residual thermal stress generated during the welding cooling stage, the copper layer can actively accommodate and dissipate this energy through its own microscopic plastic deformation, rather than rigidly transferring it to the ceramic substrate. This provides a built-in stress relaxation path for the entire connection system, further ensuring the structural integrity of the ceramic substrate and enhancing the thermal fatigue resistance of the connection parts.

[0017] 3. Ensuring ultra-high airtightness at the weld interface to guarantee the long-term stability of the vacuum gauge's core cavity: The above mechanism effectively prevents the initiation and propagation of microcracks in the ceramic substrate caused by stress, thereby eliminating the main hidden danger of vacuum seal failure. This allows the weld formed between the ceramic substrate, the metal transition layer, and the metal shell to maintain high density and continuity, meeting the extreme airtightness requirements of ultra-high vacuum applications (e.g., leakage rate ≤ 100%). (Pa·m³ / s), thus providing a durable and stable ultra-high vacuum environment for the reference vacuum chamber of the capacitive vacuum gauge, which is the fundamental guarantee for achieving high-precision and high-reliability pressure measurement.

[0018] 4. This provides a structural foundation for low-temperature, low-stress welding processes, enhancing process safety and product consistency: The introduction of this metal transition layer reduces dependence on peak welding temperatures, making the use of low-temperature brazing filler metals such as tin-silver-copper a better choice for connection. Low-temperature brazing significantly reduces overall heat input and the resulting thermal stress, while avoiding potential thermal damage to the ceramic substrate and its surface precision functional components (such as fixed electrodes and their plating) caused by high temperatures. This improves the product's process window, production yield, and performance consistency. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the connection structure between the metal shell and the ceramic substrate in a capacitive vacuum gauge with low-stress ceramic-metal welding, provided by an embodiment of the present invention.

[0020] In the figure: 1. Ceramic substrate; 2. Metal shell; 3. Metal transition layer; 31. Nickel layer; 32. Copper layer; 4. Metallization layer. Detailed Implementation

[0021] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0022] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "vertical", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0025] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0026] refer to Figure 1 An embodiment of the present invention discloses a ceramic-metal low-stress welded capacitive vacuum gauge, comprising a metal shell 2 and a ceramic substrate 1 connected to the metal shell 2, wherein a metal transition layer 3 is provided at the interface between the ceramic substrate 1 and the metal shell 2; the metal transition layer 3 is a double-layer copper-nickel composite structure having a copper layer 32 and a nickel layer 31, wherein the nickel layer 31 is in contact with the ceramic substrate 1 and the copper layer 32 is in contact with the metal shell 2; the metal transition layer 3 is an integral copper-nickel rolled composite strip, consisting only of a pure copper layer 32 and a pure nickel layer 31.

[0027] Specifically, this embodiment utilizes the copper-nickel composite structure of the metal transition layer 3 to address the stress concentration problem caused by the mismatch in thermal expansion coefficients during direct welding of the ceramic substrate 1 and the metal shell 2. The basic principle is to construct a gradient layer with a smoothly transitioning thermal expansion coefficient from the ceramic side to the metal shell 2 side. The nickel layer 31 has relatively similar thermal properties to the ceramic substrate 1, which is beneficial for interfacial bonding; the copper layer 32 is more compatible with the metal shell 2, and its good plasticity can act as a stress buffer. During the welding thermal cycle, the metal transition layer 3 can effectively absorb and disperse the thermal stress generated by the uneven shrinkage of the base materials on both sides, thereby reducing the risk of ceramic cracking. This structural design provides a guarantee for obtaining a low-leakage weld, enabling the weld to meet the low-leakage requirement (e.g., ≤). (Pa·m³ / s). Simultaneously, this structure reduces the requirement for peak welding temperatures, making it possible to employ gentler, lower-temperature joining processes, which helps protect sensitive internal components.

[0028] It should be noted that this embodiment only focuses on the connection structure between the ceramic substrate 1 and the metal shell 2. Other structures and components of the capacitive vacuum gauge can be referred to in the prior art, such as the capacitive diaphragm vacuum gauge shown in publication number CN101776502A.

[0029] In some embodiments, such as Figure 1 As shown, a metallization layer 4 is provided on the surface of the ceramic substrate 1 that is in contact with the nickel layer 31 of the metal transition layer 3. The metallization layer 4 is a single metal layer structure and is directly attached to the surface of the nickel layer 31 of the metal transition layer 3.

[0030] Specifically, ceramic materials are difficult to wet well with conventional brazing filler metals, limiting the reliability of direct welding. By forming a metallization layer 4 tightly bonded to the surface of the ceramic substrate 1, its surface solderability can be effectively improved. This metallization layer 4 becomes the key bonding interface between the ceramic substrate 1 and the upper metal transition layer 3. It can form a strong adhesion with the ceramic substrate 1, while its metallic properties ensure a reliable metallurgical bond with the metal transition layer 3 (especially its nickel layer 31) through brazing, thereby establishing a continuous and strongly bonded transition region between the ceramic and the metal.

[0031] The realization of this structure typically involves the following steps: First, the surface of the ceramic substrate 1 to be joined is pretreated by cleaning and roughening to improve surface activity and adhesion. Then, a uniform and dense metal film is deposited on this surface using processes such as magnetron sputtering, electron beam evaporation, or chemical plating to form the metallization layer 4. The metallization layer 4 is made of nickel and is directly bonded to the surface of the nickel layer 31 of the metal transition layer 3, forming a reliable metallurgical bond. After the metallization process is completed, the ceramic substrate 1 possesses an interface suitable for high-quality welding with the metal transition layer 3.

[0032] Thus, by adding a metallization layer 4 to the surface of the ceramic substrate 1, this embodiment optimizes the bonding conditions between the metallization layer 4 and the metal transition layer 3, which helps to achieve a connection with lower stress and higher reliability.

[0033] In a further embodiment, the metallization layer 4 is made of nickel and has a thickness of 5-8 μm.

[0034] Specifically, nickel was chosen as the material for the metallization layer 4 in this embodiment because nickel has good adhesion to commonly used ceramic substrates 1 (such as alumina), and nickel itself is easy to form a uniform and dense layer through processes such as electroplating or deposition. In addition, nickel has excellent compatibility and solderability with the tin-silver-copper solder used subsequently and the nickel layer 31 of the metal transition layer 3, which can ensure the formation of a strong metallurgical bond.

[0035] Specifically, the thickness of the metallization layer 4 is limited to 5 to 8 micrometers. If the metallization layer 4 is too thin (e.g., less than 5 micrometers), its function as a barrier and bonding layer may be incomplete due to uneven thickness or the presence of minor defects, making it prone to localized failure under thermal stress. If the metallization layer 4 is too thick (e.g., more than 8 micrometers), it will not only unnecessarily increase process costs and time but also introduce additional interfacial stress during subsequent welding. Controlling the thickness within this range ensures that the metallization layer 4 is continuous, dense, and has reliable adhesion, while also achieving the goals of process efficiency and low stress in the overall connection structure.

[0036] In some embodiments, the total thickness of the metal transition layer 3 is 20-30 μm.

[0037] The metal transition layer 3 consists only of a copper layer 32 and a nickel layer 31. The copper layer 32 is a pure copper layer and the nickel layer 31 is a pure nickel layer, with no other metal layer intervening between them. The primary function of the metal transition layer 3 is to provide effective thermal stress buffering between the ceramic substrate 1 and the metal shell 2. If its total thickness is too thin (e.g., less than 20 micrometers), the material's own plastic deformation capacity is limited, making it difficult to fully absorb and release the stress generated during welding and thermal cycling, potentially leading to insufficient buffering and failure to fully protect the ceramic substrate 1. Conversely, if its total thickness is too thick (e.g., more than 30 micrometers), although the stress buffering capacity may be enhanced, it will excessively increase the size of the connection joint, potentially posing challenges to the compact spatial layout inside the vacuum gauge. Furthermore, an excessively thick metal layer may also have new impacts on structural stability due to the internal stress generated during processing and welding. Controlling the total thickness within the range of 20 to 30 micrometers ensures sufficient stress buffering while maintaining the compactness and stability of the connection structure.

[0038] In some embodiments, the thickness ratio of the copper layer 32 to the nickel layer 31 in the metal transition layer 3 is 1.5:1 to 4:1.

[0039] In this structure, the nickel layer 31 primarily provides good interfacial compatibility and bonding with the ceramic substrate 1, while the copper layer 32, with its higher plasticity and coefficient of thermal expansion, mainly undertakes the key buffering function of absorbing and dissipating heat stress. If the copper layer 32 is relatively too thin (i.e., the ratio is close to 1:1 or lower), the overall plastic deformation capacity of the transition layer is insufficient, and the stress buffering effect may be limited. If the copper layer 32 is relatively too thick (i.e., the ratio exceeds 4:1), although the stress buffering capacity is enhanced, it may weaken the overall structural strength of the transition layer and the bonding stability with the ceramic side. Limiting the thickness ratio of the copper layer 32 to the nickel layer 31 to between 1.5:1 and 4:1 aims to maximize the effectiveness of the copper layer 32 in mitigating stress by utilizing its plasticity, while ensuring a reliable bond between the transition layer and the ceramic substrate 1, thereby optimizing the overall performance of the composite structure.

[0040] In some embodiments, the metal transition layer 3 is an integral copper-nickel rolled composite strip.

[0041] Specifically, the copper layer 32, made of pure copper, and the nickel layer 31, made of pure nickel, are integrated through a solid-state metal processing technology called rolling composite, without any other metal layer intervening between the copper layer 32 and the nickel layer 31. In this process, the copper strip and the nickel strip are rolled together under high pressure. The enormous pressure causes the two metals to undergo plastic deformation and atomic diffusion at the interface, ultimately forming a strong metallurgical bond, thereby obtaining an integrated composite strip.

[0042] The use of rolled composite strip as the metal transition layer 3 is primarily based on the following considerations: First, compared to electroplating, deposition, or simple physical stacking, rolling composite can form a high-strength interfacial bond between copper and nickel, ensuring that the transition layer will not delaminate during use or subsequent welding. Second, the rolling process is mature and stable, enabling precise control of strip thickness, width, and copper-nickel ratio, which helps ensure product consistency and performance reliability. Finally, the pre-formed material provided in strip form facilitates subsequent punching or cutting into the required connector shapes, simplifying assembly and making it suitable for mass production.

[0043] In some embodiments, the ceramic substrate 1, the metal transition layer 3, and the metal shell 2 are brazed at low temperature with tin-silver-copper brazing filler metal. No titanium-based brazing filler metal is used during the brazing process. The molten tin-silver-copper brazing filler metal flows, fills, and solidifies in each mating gap to form a strong brazed seam.

[0044] Specifically, the connection relies on molten tin-silver-copper solder flowing and filling the gaps between the ceramic substrate 1, the metal transition layer 3, and the metal shell 2, followed by solidification to form a strong brazed joint. The lead-free tin-silver-copper (Sn-Ag-Cu) solder system was chosen primarily because of its relatively low melting point (e.g., approximately 217°C), which allows welding to be completed at temperatures significantly lower than conventional high-temperature brazing (e.g., in the 230-250°C range).

[0045] The direct benefit of using this low-temperature brazing process is a significant reduction in heat input during the welding process. Lower thermal cycling temperatures mean less thermal stress between the ceramic substrate 1 and the metal casing 2 due to instantaneous temperature differences. Reducing the source of stress from the heat source further avoids the risk of damage to the ceramic due to thermal stress. Simultaneously, the lower temperature also helps protect delicate electrodes or other temperature-sensitive functional components that may have been fabricated on the ceramic substrate 1, preventing performance degradation due to high temperatures.

[0046] In some embodiments, the metal casing 2 is made of Kovar alloy or austenitic stainless steel.

[0047] Specifically, both Kovar alloy (an iron-nickel-cobalt alloy) and austenitic stainless steel (such as 304 or 316L) exhibit good metallurgical compatibility and weldability with copper, enabling reliable connections to be formed through the aforementioned low-temperature brazing process. Furthermore, both materials possess good vacuum performance, sufficient mechanical strength, and a certain degree of corrosion resistance.

[0048] In some embodiments, a fixed electrode (not shown) is provided on the ceramic substrate 1, and the fixed electrode is electrically connected to an external circuit via an internal wire. Specifically, the internal wire and the fixed electrode are electrically connected by resistance spot welding.

[0049] The fixed electrode is typically fabricated directly on the surface of the ceramic substrate 1 using microfabrication processes such as thin-film deposition and photolithography, serving as one plate of the sensing capacitor. To transmit the capacitance change signal to external measurement and processing circuitry, a highly conductive internal wire (e.g., gold, aluminum, or nickel-plated alloy wire) is used to connect the electrical contact on the fixed electrode to the inner end of an insulated, sealed terminal (e.g., a glass-to-metal or ceramic-to-metal sealed terminal) that penetrates the metal casing 2. This terminal ensures that the electrical signal is extracted from the vacuum-sealed cavity without compromising its overall airtightness.

[0050] This embodiment achieves the electrical connection between the internal wires and the fixed electrode through resistance spot welding. The heat input of resistance spot welding is highly localized and the action time is extremely short (typically on the order of milliseconds), resulting in a very small heat-affected zone. This minimizes the adverse thermal effects on adjacent, temperature-sensitive ceramic substrates, existing low-stress welds, or other functional areas.

[0051] In summary, this invention provides a capacitive vacuum gauge with low-stress ceramic-metal welding, which has the following advantages: 1. Achieving a gradient match in the coefficient of thermal expansion, significantly reducing welding stress at its source: The copper-nickel composite structure of the metal transition layer 3 constructs a physical buffer zone with a gradual change in performance between the ceramic substrate 1 and the metal shell 2. The nickel layer 31, due to its relatively low coefficient of thermal expansion, is more compatible with the ceramic substrate 1 side; the copper layer 32, due to its relatively high coefficient of thermal expansion, is closer to the metal shell 2 side. This design creates a continuous gradient in the coefficient of thermal expansion, effectively absorbing and dispersing the interfacial shear stress and tensile stress caused by the inconsistent shrinkage of the materials on both sides during the welding thermal cycle. This fundamentally avoids stress concentration at the brittle interface of the ceramic substrate 1, significantly reducing the risk of cracking of the ceramic substrate 1.

[0052] 2. Utilizing the excellent plastic deformation capability of the copper layer 32 to actively absorb and release residual stress: The copper layer 32 possesses good ductility and plasticity. Under the action of residual thermal stress generated during the welding cooling stage, the copper layer 32 can actively accommodate and dissipate this energy through its own microscopic plastic deformation, rather than rigidly transferring it to the ceramic substrate 1. This provides a built-in stress relaxation path for the entire connection system, further ensuring the structural integrity of the ceramic substrate 1 and enhancing the thermal fatigue resistance of the connection parts.

[0053] 3. Ensuring ultra-high airtightness at the weld interface to guarantee the long-term stability of the vacuum gauge's core cavity: The above mechanism effectively prevents the initiation and propagation of microcracks in the ceramic substrate 1 caused by stress, thereby eliminating the main hidden danger of vacuum seal failure. This allows the weld formed between the ceramic substrate 1, the metal transition layer 3, and the metal shell 2 to maintain high density and continuity, meeting the extreme airtightness requirements of ultra-high vacuum applications (e.g., leakage rate ≤ 100%). (Pa·m³ / s), thus providing a durable and stable ultra-high vacuum environment for the reference vacuum chamber of the capacitive vacuum gauge, which is the fundamental guarantee for achieving high-precision and high-reliability pressure measurement.

[0054] 4. The introduction of the metal transition layer 3 provides a structural foundation for low-temperature, low-stress welding processes, enhancing process safety and product consistency. This reduces dependence on peak welding temperatures, making the use of low-temperature brazing filler metals such as tin-silver-copper a more preferable option. The low-temperature brazing process significantly reduces overall heat input and the resulting thermal stress, while avoiding potential thermal damage to the ceramic substrate 1 and its surface precision functional components (such as fixed electrodes and their plating) caused by high temperatures. This improves the product's process window, production yield, and performance consistency.

[0055] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A ceramic-metal low-stress welded capacitive vacuum gauge, comprising a metal housing and a ceramic substrate connected to the metal housing, characterized in that, A metal transition layer is provided at the interface between the ceramic substrate and the metal shell; the metal transition layer is a double-layer copper-nickel composite structure with a copper layer and a nickel layer, the nickel layer is in contact with the ceramic substrate, and the copper layer is in contact with the metal shell.

2. The capacitive vacuum gauge with low-stress ceramic-metal welding according to claim 1, characterized in that: The surface of the ceramic substrate in contact with the metal transition layer is provided with a metallization layer.

3. The capacitive vacuum gauge with low-stress ceramic-metal welding according to claim 2, characterized in that: The metallization layer is directly bonded to the nickel layer surface of the metal transition layer.

4. The capacitive vacuum gauge with low-stress ceramic-metal welding according to claim 3, characterized in that: The metallization layer is made of nickel.

5. The capacitive vacuum gauge with low-stress ceramic-metal welding according to claim 1, characterized in that: The metal transition layer is an integral copper-nickel rolled composite strip.

6. The capacitive vacuum gauge with low-stress ceramic-metal welding according to claim 5, characterized in that: The metal transition layer consists only of a copper layer and a nickel layer, wherein the copper layer is a pure copper layer and the nickel layer is a pure nickel layer.

7. The capacitive vacuum gauge with low-stress ceramic-metal welding according to claim 1, characterized in that: The ceramic substrate, the metal transition layer, and the metal shell are brazed at low temperature using tin-silver-copper brazing filler metal, without the use of titanium-based brazing filler metal components during the brazing process.

8. The capacitive vacuum gauge with low-stress ceramic-metal welding according to claim 1, characterized in that: The metal casing is made of Kovar alloy or austenitic stainless steel.

9. The capacitive vacuum gauge with low-stress ceramic-metal welding according to claim 1, characterized in that: A fixed electrode is provided on the ceramic substrate, and the fixed electrode is electrically connected to an external circuit through an internal wire.

10. The ceramic-metal low-stress welded capacitive vacuum gauge according to claim 9, characterized in that: The internal wires are electrically connected to the fixed electrode by resistance spot welding.

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