Miniature ionization vacuum sensor based on PCB technology and method of manufacturing the same

Abstract

The application discloses a micro ionization vacuum sensor based on a PCB process and a manufacturing method thereof, all of a sensor cathode bearing layer, a grid layer, an ion collection layer and an insulating spacing layer are integrally formed by using a standardized PCB process; the device is prepared in batches through a complete flow of PCB layout design, plate forming, electrode metallization, emitter assembly, multi-layer accurate lamination and baking detection; the micro ionization vacuum sensor comprises a cathode bearing plate, two layers of insulating spacing plates, a grid plate and an ion collection plate, cavity windows of the layers are combined to form an ionization cavity, and electrodes are led out through metallized through holes; the application can be mass-produced by using a common PCB factory, has high batch consistency and low single-piece cost, can be integrated with a peripheral detection circuit board, is suitable for large-batch micro vacuum monitoring scenes of semiconductor, vacuum coating and portable vacuum equipment.

Description

Technical Field

[0001] This invention belongs to the field of vacuum sensor manufacturing technology, specifically relating to a miniature ionization vacuum sensor based on PCB technology and its manufacturing method. Background Technology

[0002] Ionization vacuum sensors rely on the emission of electrons from the cathode. These electrons collide with gas molecules within the vacuum chamber, ionizing to generate positive ions. The ion collecting electrode captures the ion current and converts it into vacuum pressure, making it the mainstream detection device in the high vacuum range. Currently, the mainstream fabrication routes for miniature ionization vacuum sensors are divided into mechanical assembly and MEMS microfabrication routes. Both suffer from core technological drawbacks, namely high processing barriers and high unit manufacturing costs for miniaturized, high-volume vacuum monitoring applications.

[0003] Traditional machined ionization vacuum sensors are assembled from metal cylinders, discrete electrode rods, filament supports, and insulating components. Electrode coaxiality and interlayer spacing have high requirements for machining and manual assembly and debugging. Human error directly leads to batch performance dispersion, and the processing cycle is long, which cannot meet the needs of miniaturization and low-cost mass deployment.

[0004] Existing miniaturized MEMS ionization vacuum sensors use silicon wafers and glass as substrates, relying on specialized micro- and nano-scale equipment such as photolithography, thin film deposition, anodic bonding, laser bonding, and wafer micro-etching to fabricate multi-layer cavity electrode structures. While this approach can achieve device miniaturization, the entire process requires a cleanroom of Class 10,000 or higher, wafer bonding machines, and high-precision laser micromachining equipment, resulting in extremely high equipment investment and outsourcing costs. Furthermore, the silicon / glass micromachining process window is narrow, and the tolerance for errors in electrode spacing and cavity size is low. After device fabrication, additional secondary packaging is required to connect with external detection and driving circuits, further increasing the overall application cost.

[0005] For high-volume, low-cost micro vacuum monitoring scenarios such as vacuum-encapsulated components, portable vacuum systems, and teaching experimental platforms, the MEMS microfabrication route suffers from high equipment dependence, scarce outsourcing resources, high unit cost, and complex circuit integration. Existing technologies lack mature, low-cost, mass-production alternatives, making it difficult to achieve large-scale widespread application of micro ionization vacuum sensors. Summary of the Invention

[0006] To address the technical challenges of existing MEMS silicon / glass-based micro ionization vacuum sensors, which rely on specialized microfabrication equipment such as cleanrooms, wafer bonding, and deep silicon etching, resulting in high processing barriers, high unit costs, and difficulties in board-level circuit integration, this invention provides a micro ionization vacuum sensor and its manufacturing method based on PCB technology. This method uses standardized PCB mass production processes to integrate electrode patterns, interlayer interconnects, ionization cavities, and positioning references, eliminating reliance on specialized MEMS microfabrication equipment, lowering processing barriers, simplifying procedures, reducing unit costs, improving batch consistency, and achieving integrated integration of the sensor with peripheral detection and driving circuit boards.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for manufacturing a miniature ionization vacuum sensor based on PCB technology includes the following steps:

[0009] Step S1: PCB panel layout design. According to the sensor stack-up structure, arrange the cathode power supply pattern, gate pattern, ion collection pattern, interlayer positioning reference pattern, and external connection pads on different PCB functional layers or the same board material.

[0010] Step S2: Functional board cutting and forming. The cathode support plate, the first spacer plate, the gate plate, the second spacer plate, and the ion collection plate are respectively prepared by PCB cutting, mechanical drilling and laser milling processes. The board shape, central cavity window, external communication hole and interlayer positioning hole are respectively prepared.

[0011] Step S3: Electrode metallization forming. Through copper plating, electroplating, pattern transfer, etching, solder mask opening, and vacuum-compatible surface treatment, emitter connection pads, accelerating gate electrodes, ion collecting electrodes, first metallized vias, second metallized vias, external lead-out pads, and ion collecting pads are formed on the cathode carrier plate, gate plate, and ion collecting plate.

[0012] Step S4: Electron emitter assembly, fixing the electron emitter to the emitter connection pad;

[0013] Step S5: Sensor stacking and assembly. The alignment of each plate is completed by relying on positioning holes and optical recognition marks. The cathode support plate, the first spacer plate, the gate plate, the second spacer plate, and the ion collection plate are fixed in sequence by means of bonding, low temperature welding, riveting, screw connection or combination. The windows of each cavity are connected to form a sealed ionization cavity, and the external connecting hole is connected to the ionization cavity.

[0014] Step S6: Post-processing and inspection. The stacked device is baked at high temperature to remove gas, and then the cathode resistance, electrode insulation and ion collection path electrical performance are tested to obtain the finished miniature ionization vacuum sensor. The emitter connection pad, accelerating gate electrode, ion collection electrode, first metallized via, second metallized via, ionization cavity size and interlayer positioning hole are all integrally formed by PCB standard processing.

[0015] In a preferred embodiment of the present invention, the cathode support plate, the first spacer plate, the gate plate, the second spacer plate, and the ion collection plate are made of FR-4, ceramic PCB, polyimide PCB, PTFE high-frequency PCB, Rogers substrate, or composite insulating material.

[0016] In a preferred embodiment of the present invention, in step S3, the vacuum-compatible surface treatment is at least one of immersion nickel-gold, hard gold, electroplated gold, immersion silver, immersion tin, nickel-palladium-gold, and anti-oxidation treatment, which is used to reduce the electrode oxidation rate, reduce contact resistance, and suppress the release of pollutants from the vacuum environment.

[0017] In a preferred embodiment of the present invention, in step S3, the accelerating gate electrode of the gate plate is formed by any one of the following: PCB copper foil etched mesh, electroplated thickened metal mesh, metallized through-hole array, or embedded metal mesh; the through-hole array is prepared by mechanical drilling, laser drilling, controlled depth milling, plasma opening, or punching process.

[0018] In a preferred embodiment of the present invention, in step S5, the first spacer and the second spacer are PCB core boards with a central window, prepregs, ceramic insulating sheets, polyimide insulating sheets, or combinations thereof. The thickness of the first spacer limits the distance between the electron emitter and the accelerating gate electrode, and the thickness of the second spacer limits the distance between the accelerating gate electrode and the ion collector electrode.

[0019] In a preferred embodiment of the present invention, in step S1, several sensor unit arrays are arranged on the same PCB panel. From step S2 to step S6, the entire process involves synchronous batch processing, assembly, baking, and electrical testing on a panel-by-panel basis. After passing the test, independent individual sensors are obtained by V-cutting, stamp hole cutting, milling, and laser cutting.

[0020] In a preferred embodiment of the present invention, in step S6, before baking and degassing or after detection, a magnetic field unit consisting of a permanent magnet, a magnetic ring, and an electromagnetic coil is installed on the outside of the ionization cavity; the magnetic field unit is fixed to the outside of the sensor board through a PCB pre-reserved mounting slot, positioning hole, adhesive, and snap-fit ​​structure.

[0021] A miniature ionization vacuum sensor based on PCB technology, fabricated using the aforementioned method, comprises a cathode support plate, a first spacer plate, a gate plate, a second spacer plate, and an ion collection plate stacked sequentially. The cathode support plate is a PCB-compatible material with emitter connection pads and external lead-out pads on it, and a first metallized via is provided between the emitter connection pads and the external lead-out pads. An electron emitter is fixed on the emitter connection pads. A first cavity window is formed in the first spacer plate. The gate plate is formed with a PCB metallized accelerating gate electrode. A second cavity window is formed in the second spacer plate. The ion collection plate has an ion collecting electrode and an external communication hole. A magnetic field unit is provided on the outside of the ion collection plate. The cavity windows of each layer are interconnected to form an ionization cavity. The accelerating gate electrode and the ion collecting electrode are connected to the external gate pad and the ion collecting pad respectively through inner PCB traces and the second metallized via.

[0022] In a preferred embodiment of the present invention, the accelerating gate electrode is selected from a copper foil etched mesh, an electroplated nickel-gold composite mesh, and a metallized via array structure. The accelerating gate electrode and the external gate pad are interconnected through inner layer traces or vertical metallized vias.

[0023] In a preferred embodiment of the present invention, the first spacer and the second spacer are prepared using at least one of PCB core board, prepreg, and ceramic insulating sheet, and the spacing tolerance of the electrode layers inside the ionization cavity is precisely controlled by relying on the thickness tolerance of the spacer.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. Significantly reduces the barriers to processing equipment and environment, avoiding reliance on MEMS-specific equipment. This invention transforms all electrodes, cavities, positioning, and interconnect structures of ionization sensors into standardized and mature processes in the PCB industry. The entire process eliminates the need for MEMS-specific equipment such as silicon deep etching, glass thin film deposition, anodic bonding, and laser wafer bonding. Ordinary PCB processing plants can complete all processing, with ample outsourcing resources. This fundamentally solves the core problems of high equipment investment and scarce processing channels in existing MEMS solutions, giving it a strong advantage for industrialization.

[0026] 2. Significantly reduces unit manufacturing costs and adapts to mass production. The PCB industry has mature panel production technology, and dozens to hundreds of sensor units can be arranged on a single panel. The entire process of material cutting, drilling, electroplating, etching, surface treatment, lamination, and depaneling is completed simultaneously in batches. By using the standard PCB board thickness and prepreg thickness to control the electrode spacing, the high-precision wafer processing and single-chip packaging processes of MEMS are eliminated, significantly reducing processing and manufacturing costs and meeting the massive low-cost application needs of portable devices and teaching platforms.

[0027] 3. Improve batch consistency of components and eliminate manual assembly errors. The tolerances of PCB process linewidth, hole diameter, board thickness, and positioning hole size are industry-standard control indicators. Multilayer boards rely on unified optical positioning marks and positioning hole reference alignment. The batch dispersion of electrode spacing, cavity window coaxiality, and pad position is much lower than that of manual assembly. Completely avoid the performance fluctuations caused by the manual assembly and debugging of traditional sensors, and significantly improve the product inspection yield.

[0028] 4. Simplified manufacturing process, achieving integrated sensor and drive circuit. The present invention uses metallized vias to directly achieve vertical interconnection of multi-layer electrodes. The external pads are fully compatible with the design specifications of PCB drive, amplification and detection circuits, eliminating the need for additional leads and secondary packaging adapter structures. The spacer layer directly uses PCB core board / prepreg, eliminating the need for separate processing of insulating pads, shortening the process flow and further miniaturizing the overall device size.

[0029] 5. Strong process scalability, adaptable to various vacuum conditions and optimized for upgrades. PCB substrates can be freely replaced to adapt to different vacuum levels: FR-4 is suitable for conventional medium and high vacuum, while ceramic PCBs are suitable for high temperature, ultra-low outgassing, and ultra-high vacuum scenarios; supports single-layer / multi-layer composite accelerating gates, ion collector protection rings, external magnetic field units, and other extended structures; interlayer fixing methods can be flexibly selected, including bonding, screws, and thermoforming lamination, accommodating both mass standardized production and detachable debugging R&D scenarios.

[0030] 6. The measured vacuum detection performance meets the standards, and its functional integrity is on par with MEMS devices. Vacuum calibration tests show that the effective measurement range of the PCB-based miniature ionization vacuum sensor of this invention covers 10... -4 With a range of five orders of magnitude from ~1Pa, the ion current changes linearly with the vacuum level. The ionization and ion collection mechanisms are complete, and the measurement accuracy meets the needs of conventional industrial vacuum monitoring. It achieves equivalent detection performance to MEMS micro ionization sensors at low cost. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the stacked structure of a miniature ionization vacuum sensor based on PCB technology, provided for an embodiment of the present invention.

[0033] Figure 2 This is a flowchart illustrating the complete fabrication and assembly process of the miniature ionization vacuum sensor provided in an embodiment of the present invention; wherein, Figure 2(a) shows the molding steps of each layer of the PCB functional board. Figure 2 (b) describes the assembly steps of the electron emitter. Figure 2 (c) represents the sensor stacking assembly steps.

[0034] Figure 3 The images provided in this embodiment of the invention show the completed physical images of each independent PCB functional layer; wherein, Figure 3 (a) is a physical image of the cathode support plate. Figure 3 (b) is a physical image of the first / second partition plate. Figure 3 (c) is a physical diagram of the gate plate. Figure 3 (d) is a physical image of the ion collecting plate.

[0035] Figure 4 This is a physical image of a sensor assembled from multiple layers of sheet metal, as provided in an embodiment of the present invention.

[0036] Figure 5 This is a physical assembly diagram of the sensor installed on the vacuum test base according to an embodiment of the present invention.

[0037] Figure 6 This is a schematic diagram of a sensor expansion structure with an added magnetic field unit provided in an embodiment of the present invention;

[0038] Figure 7 The diagram shows the vacuum degree-normalized ion current calibration test curve of the PCB-based sensor provided in this embodiment of the invention.

[0039] Explanation of reference numerals in the attached drawings: 1. Cathode support plate; 2. Emitter connection pad; 3. External lead-out pad; 4. First metallized via; 5. Electron emitter; 6. First spacer; 7. Gate plate; 8. Second spacer; 9. Ion collecting plate; 10. Ion collecting electrode; 11. Second metallized via; 12. External connecting hole; 13. Magnetic field unit; 14. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0041] like Figures 1-6 As shown, this embodiment of the invention provides a method for manufacturing a miniature ionization vacuum sensor based on PCB technology, comprising the following steps:

[0042] Step S1: PCB panel layout design. According to the sensor stack-up structure, arrange the cathode power supply pattern, gate pattern, ion collection pattern, interlayer positioning reference pattern, and external connection pads on different PCB functional layers or the same board material.

[0043] Step S2: Functional board cutting and forming. The cathode carrier plate 1, the first spacer plate 6, the gate plate 7, the second spacer plate 8, and the ion collection plate 9 are respectively prepared by PCB cutting, mechanical drilling and laser milling processes. The board shape, central cavity window, external communication hole 13 and interlayer positioning hole are respectively prepared.

[0044] Step S3: Electrode metallization forming, through copper plating, electroplating, pattern transfer, etching, solder mask opening, and vacuum compatible surface treatment, emitter connection pad 2, accelerating gate electrode, ion collecting electrode 10, first metallized via 4, second metallized via 12, external lead-out pad 3, and ion collecting pad 11 are formed on cathode carrier plate 1, gate plate 7, and ion collecting plate 9.

[0045] Step S4: Electron emitter assembly, fix the electron emitter 5 to the emitter connection pad 2;

[0046] Step S5: Sensor stacking assembly. The alignment of each plate is completed by relying on positioning holes and optical recognition marks. The cathode support plate 1, the first spacer plate 6, the gate plate 7, the second spacer plate 8, and the ion collection plate 9 are fixed in sequence by bonding, low temperature welding, riveting, screw connection or combination. The windows of each cavity are connected to form a sealed ionization cavity. The external connection hole 13 is connected to the ionization cavity.

[0047] Step S6: Post-processing and testing. The stacked device is baked at high temperature to remove gas, and then the cathode resistance, electrode insulation, and electrical performance of the ion collection path are tested to obtain the finished miniature ionization vacuum sensor. The emitter connection pad 2, accelerating gate electrode, ion collection electrode 10, first metallized via 4, second metallized via 12, ionization cavity size, and interlayer positioning holes are all integrally formed by standard PCB processing to reduce the dependence of sensor fabrication on silicon-based micromachining, glass micromachining, and wafer-level bonding equipment.

[0048] The cathode support plate 1, the first spacer plate 6, the gate plate 7, the second spacer plate 8, and the ion collection plate 9 are made of FR-4, ceramic PCB, polyimide PCB, PTFE high-frequency PCB, Rogers substrate, or composite insulating material.

[0049] In step S3, the vacuum-compatible surface treatment is at least one of the following: immersion nickel gold, hard gold, electroplated gold, immersion silver, immersion tin, nickel palladium gold, and anti-oxidation treatment, used to reduce the electrode oxidation rate, reduce contact resistance, and suppress the release of pollutants from the vacuum environment.

[0050] In step S3, the accelerating gate electrode of the gate plate 7 is formed by any one of the following: PCB copper foil etched mesh, electroplated thickened metal mesh, metallized through-hole array, or embedded metal mesh; the through-hole array is prepared by mechanical drilling, laser drilling, controlled depth milling, plasma opening, or punching process.

[0051] In step S5, the first spacer 6 and the second spacer 8 are PCB core boards with a center window, prepregs, ceramic insulating sheets, polyimide insulating sheets or assemblies. The thickness of the first spacer 6 limits the distance between the electron emitter 5 and the accelerating gate electrode, and the thickness of the second spacer 8 limits the distance between the accelerating gate electrode and the ion collector electrode 10.

[0052] In step S1, several sensor unit arrays are arranged on the same PCB panel. From step S2 to step S6, the entire process involves synchronous batch processing, assembly, baking, and electrical testing on a panel-by-panel basis. After passing the test, individual individual sensors are obtained by V-cutting, stamp hole cutting, milling, and laser cutting.

[0053] In step S6, before baking and degassing or after testing, a magnetic field unit 14 consisting of a permanent magnet, a magnetic ring, and an electromagnetic coil is installed on the outside of the ionization cavity; the magnetic field unit 14 is fixed to the outside of the sensor board through a PCB pre-reserved mounting slot, positioning hole, adhesive, and snap-fit ​​structure.

[0054] The above describes the process of first designing the multi-layer PCB functional board layout for the sensor, distinguishing the patterns of the cathode carrier layer, gate layer, ion collection layer, and insulating spacer layer; then, fabricating the shape, cavity window, positioning hole, and gas communication hole of each board using standard PCB machining; shaping the emitter pads, accelerating gate, ion collection electrode, and metallized interconnecting vias using copper plating, electroplating, pattern transfer, etching, and vacuum-compatible surface treatment; fixing the electron emitter on the cathode carrier board pads; precisely aligning multiple layers using positioning hole references, and stacking and assembling them using a combination of adhesive / lamination / mechanical fastening to form a sealed ionization cavity; completing device baking and degassing, and electrical performance testing; and finally, separating the boards to obtain the individual sensor.

[0055] Figure 6 Combination Figure 1This invention also provides a miniature ionization vacuum sensor based on PCB technology, manufactured using the above-described method. It comprises a cathode support plate 1, a first spacer plate 6, a gate plate 7, a second spacer plate 8, and an ion collection plate 9 stacked sequentially. The cathode support plate 1 is a PCB-compatible material, on which emitter connection pads 2 and external lead-out pads 3 are provided. A first metallized via 4 is provided between the emitter connection pad 2 and the external lead-out pad 3. An electron emitter 5 is fixed on the emitter connection pad 2. A first cavity window is formed in the first spacer plate 6. The gate plate 7 forms a PCB metallized accelerating gate electrode. A second cavity window is formed in the second spacer plate 8. The ion collection plate 9 is provided with an ion collecting electrode 10 and an external communication hole 13. A magnetic field unit 14 is provided on the outside of the ion collection plate 9. The cavity windows of each layer are interconnected to form an ionization cavity. The accelerating gate electrode and the ion collecting electrode 10 are connected to the external gate pad and the ion collecting pad 11 respectively through the first metallized via 4, the second metallized via 12, and the inner PCB traces.

[0056] The accelerating gate electrode uses a copper foil etched mesh, an electroplated nickel-gold composite mesh, or a metallized via array structure. The accelerating gate electrode is interconnected with the external gate pad through inner layer traces or vertical metallized vias. The first spacer 6 and the second spacer 8 are fabricated using at least one of PCB core board, prepreg, or ceramic insulating sheet. The spacing tolerance of the electrode layers inside the ionization cavity is precisely controlled by relying on the thickness tolerance of the spacer.

[0057] In some embodiments, an electron emitter is mounted on an emitter connection pad for generating electrons. A first spacer 6 is stacked on the cathode carrier plate 1 and has a first cavity window. A gate plate 7 is stacked on the first spacer 6 and has an accelerating gate electrode formed by PCB metallization patterns; a second spacer 8 is stacked on the gate plate 7 and has a second cavity window. An ion collecting plate 9 is stacked on the second spacer 8 and has an external communication hole that communicates with both the first and second cavity windows. The cathode carrier plate 1, the first spacer 6, the gate plate 7, the second spacer 8, and the ion collecting plate 9 are fixed by a PCB-level stacking method. The electron emitter connection pad, the accelerating gate electrode, and the ion collecting electrode are all led out through PCB metallization vias, PCB traces, or external pads.

[0058] In some embodiments, the accelerating gate electrode can be a single-layer grid or a multi-layer gate combination; the multi-layer gate can be formed by connecting the inner and outer copper foils and metallized vias of a multilayer PCB board. The ion collecting electrode can be disposed on the inner surface of the ion collecting plate, or it can be disposed on the outer surface through structural design. Alternatively, it can be disposed on another PCB board adjacent to the ion collecting plate, and the ion collecting area can be defined by inter-board spacers. Interlayer fixing can be achieved by integral lamination, partial bonding, or mechanical pressing; when disassembly or replacement of the structure is required, screw connection, elastic clamping, or detachable metal frame fixing is preferred.

[0059] For applications requiring further reduction in leakage current, protective ring electrodes, solder resist isolation grooves, or highly insulating ceramic isolation components can be installed around the ion collecting electrode.

[0060] The working principle of a miniature ionization vacuum sensor based on PCB technology is as follows: During use, a current or emission driving voltage is applied to the electron emitter to generate electrons. Corresponding biases are applied to the accelerating gate electrode, ion collector, and other structures, causing electrons to move within the ionization cavity and collide with gas molecules to generate positive ions. These positive ions are captured by the ion collector under the influence of an electric field. The weak current output from the ion collector is converted into a voltage signal by a transimpedance amplifier circuit, and the pressure of the gas to be measured is obtained according to the calibration relationship. The measurement mechanism of this invention can utilize existing optimized electrode biasing methods, and the aforementioned electrodes, cavity, interconnections, and assembly can be achieved through PCB-level processes, making this type of sensor easier to fabricate in a low-cost, mass-produced, and integrated manner.

[0061] Example 1: PCB board level sensor structure.

[0062] like Figure 1 As shown, in some embodiments, the PCB-based miniature ionization vacuum sensor includes a cathode carrier plate 1, an emitter connection pad 2, an external lead-out pad 3, a first metallized via 4, an electron emitter 5, a first spacer 6, a gate plate 7, a second spacer 8, an ion collection plate 9, an ion collection electrode 10, an ion collection pad 11, a second metallized via 12, and an external communication hole 13.

[0063] The cathode support plate 1, the gate plate 7, and the ion collection plate 9 can all be made of PCB board or PCB-compatible board; the first spacer plate 6 and the second spacer plate 8 can be made of windowed PCB core board, prepreg, or ceramic insulating sheet.

[0064] The cathode support plate 1 is provided with an emitter connection pad 2 and an external lead-out pad 3, which are connected by PCB traces or a first metallized via 4. The electron emitter 5 can be a thermionic, field-emission, or photoelectric material, such as a tungsten filament, iridium filament, oxide cathode, or carbon nanotube emitter. The electron emitter 5 is mounted on the emitter connection pad 2 by welding, brazing, conductive adhesive, bonding, or clamping.

[0065] An accelerating gate electrode is disposed on the gate plate 7. The accelerating gate electrode can be formed by etching copper foil to form a grid pattern, or an array of vias can be formed on the PCB substrate and the via walls can be plated with copper to obtain a metallized via array gate with high mechanical stability. The accelerating gate electrode is connected to the external gate pad through metallized vias or inner layer traces.

[0066] The first spacer 6 and the second spacer 8 each have a cavity window, and the two cavity windows together with the opening area of ​​the gate plate 7 form an ionization cavity. The thickness of the first spacer 6 and the second spacer 8 can be selected according to the required electrode spacing of the sensor, for example, from 0.1 mm to 5 mm. By selecting a standard plate thickness or stacking multiple layers of prepreg, a stable interlayer spacing can be obtained without complex microfabrication.

[0067] An external communication hole 13 and an ion collecting electrode 10 are provided on the ion collecting plate 9. The ion collecting electrode 10 can be formed from a PCB copper foil pattern and its surface stability can be improved by immersion nickel gold, hard gold or electroplating gold treatment.

[0068] like Figure 2 As shown, the embodiment provides a method for fabricating a miniature ionization vacuum sensor based on PCB technology. Figure 3 These are physical images of the functional layers of a miniature ionization vacuum sensor fabricated using PCB technology. Figure 4 For the actual assembly, Figure 5 The sensor is then fixed to the test base.

[0069] During operation, electron emitter 5 emits electrons, which collide with gas molecules in the target gas within the electric field formed by the accelerating grid, generating positive ions. These positive ions are captured by ion collector 10, forming an ion current that is related to the gas pressure.

[0070] Example 2: Panel-level PCB fabrication process.

[0071] This embodiment provides a manufacturing process suitable for mass production. First, a panel design is performed based on the sensor unit size, pad position, interlayer positioning hole position, and board frame size, and multiple sensor units are arranged on the same PCB panel.

[0072] Next, the cathode support plate, gate plate, and ion collection plate are fabricated separately. The cathode support plate is formed by drilling, copper plating, electroplating, exposure and development, etching, and solder mask opening to form emitter connection pads and external pads; the gate plate is formed by etching copper foil or metallizing via array to form accelerating gate electrodes; the ion collection plate is formed by pattern transfer to form ion collecting electrodes, and each electrode is led out through metallized vias or edge pads.

[0073] Next, the first and second spacers are fabricated. The spacers can be formed into the central cavity window on the PCB core board, prepreg, or insulating sheet by milling, punching, or laser drilling. By selecting the thickness of the spacers and the adhesive layer, the cavity height and critical electrode spacing of the sensor can be directly determined.

[0074] Subsequently, electron emitters are mounted on the cathode carrier plate. For filamentary emitters, their ends can be welded, spot-welded, or brazed to the emitter connection pads; for array-type emitters, they can be fixed by mounting, bonding, or low-temperature sintering.

[0075] Then, the cathode support plate, first spacer plate, grid plate, second spacer plate, and ion collecting plate are stacked sequentially, aligned through the positioning holes, and fixed using vacuum-compatible adhesive, hot-press lamination, riveting, or screw connections. After stacking and fixing, the plates are baked to reduce the influence of residual flux, adhesives, or volatiles on vacuum measurements.

[0076] Finally, the panel is subjected to electrical performance tests, including cathode resistance, gate conductivity, inter-electrode insulation resistance, ion collector leakage current, and external pad connectivity. After passing the tests, the panel is separated using V-cut, stamp hole, milling, or laser cutting methods to obtain individual PCB-processed ionization vacuum sensors.

[0077] Example 3: PCB-compatible mounting of the magnetic field unit.

[0078] like Figure 6 As shown, in this embodiment, the sensor can also be equipped with a magnetic field unit 14. The magnetic field unit 14 can be a permanent magnet, a magnetic ring, a magnetic sheet assembly, or an electromagnetic coil. Unlike traditional individual mechanical fixtures, PCB manufacturing processes allow for pre-drilling of mounting holes, slots, pads, copper foil limiting areas, or non-metallic reinforcing parts on the cathode carrier plate and ion collection plate to fix the magnetic field unit 14.

[0079] The magnetic field unit 14 is not a necessary feature for lowering the process threshold in this invention, but rather a functional extension compatible with the PCB board-level structure. When it is necessary to increase the electron movement path or improve electron confinement, the magnetic field unit 14 can be installed on the outside of the PCB board-level structure; when the application scenario focuses more on low cost or simplified structure, the magnetic field unit 14 can also be omitted.

[0080] Example 4: Low outgassing and vacuum resistance treatment.

[0081] Considering the operating environment of vacuum sensors, the PCB material and surface treatment can be selected according to the target vacuum range. For general vacuum applications, FR-4, polyimide, or Rogers substrates can be used; for environments with lower outgassing or higher temperatures, ceramic PCBs can be used.

[0082] Electrode surfaces are preferably treated with immersion nickel-gold, hard gold, nickel-palladium-gold, or electroplated gold to reduce oxidation, decrease contact resistance, and improve surface stability. Vacuum stability is prioritized for lamination and fixation, such as using vacuum-compatible adhesives and screw connections. Vacuum baking can be performed after device completion to reduce organic residues.

[0083] like Figure 7 As shown, a miniature ionization vacuum sensor fabricated using PCB technology was tested, with the test range covering 10... -4 The five orders of magnitude of -1 Pa, along with the different ion current responses at different pressures, validates the functional feasibility. It also possesses the following characteristics:

[0084] 1. Reduced process requirements: This invention transforms electrode fabrication, via interconnection, cavity windowing, and interlayer positioning into routine steps in PCB manufacturing, avoiding the need for silicon deep etching, glass micromachining, vacuum thin film deposition, anodic bonding, and laser bonding as essential processes, thus reducing reliance on cleanrooms and dedicated MEMS equipment.

[0085] 2. Cost reduction: PCB cutting, drilling, copper plating, electroplating, pattern transfer, etching, solder mask opening, surface treatment and panel division are all mature mass production processes. Multiple sensor units can be fabricated simultaneously through panelization, reducing the cost of single-piece processing and assembly.

[0086] 3. Simplified process: This invention uses PCB board thickness, copper thickness, prepreg thickness and lamination structure to determine key dimensions, uses metallized vias to interconnect the upper and lower surface electrodes, and uses standard pads to directly connect the peripheral circuits, thereby reducing multiple transfer, bonding, wire bonding and packaging steps.

[0087] 4. Improved consistency: The PCB process has stable control over line width / spacing, hole diameter, board thickness and interlayer positioning, which can improve batch consistency of electrode spacing, hole position and pad position.

[0088] 5. High scalability: By changing the PCB substrate, surface treatment, board thickness specifications and board-level fixing method, it can be adapted to different scenarios such as low cost, small batch R&D, and structural optimization.

[0089] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a miniature ionization vacuum sensor based on PCB technology, characterized in that, Includes the following steps: Step S1: PCB panel layout design. According to the sensor stack-up structure, arrange the cathode power supply pattern, gate pattern, ion collection pattern, interlayer positioning reference pattern, and external connection pads on different PCB functional layers or the same board material. Step S2: Functional board cutting and forming. The cathode carrier plate (1), the first spacer plate (6), the gate plate (7), the second spacer plate (8), and the ion collection plate (9) are respectively prepared by PCB cutting, mechanical drilling and laser milling processes. The board shape, central cavity window, external communication hole (13) and interlayer positioning hole are respectively prepared. Step S3: Electrode metallization is performed by copper plating, electroplating, pattern transfer, etching, solder mask opening, and vacuum compatible surface treatment to form emitter connection pads (2), accelerating gate electrode, ion collecting electrode (10), first metallized via (4), second metallized via (12), external lead-out pads (3), and ion collecting pads (11) on the cathode support plate (1), gate plate (7), and ion collecting plate (9). Step S4: Electron emitter assembly, the electron emitter (5) is fixedly installed on the emitter connection pad (2); Step S5: Sensor stacking assembly. The alignment of each plate is completed by relying on the positioning holes and optical recognition marks. The cathode support plate (1), the first spacer plate (6), the gate plate (7), the second spacer plate (8), and the ion collection plate (9) are fixed in sequence by means of bonding, low temperature welding, riveting, screw connection or combination. The windows of each cavity are connected to form a closed ionization cavity. The external connecting hole (13) is connected to the ionization cavity. Step S6: Post-processing and testing. The stacked device is baked at high temperature to remove gas, and then the cathode resistance, electrode insulation and ion collection path electrical performance are tested to obtain the finished miniature ionization vacuum sensor. The emitter connection pad (2), acceleration gate electrode, ion collection electrode (10), first metallized via (4), second metallized via (12), ionization cavity size and interlayer positioning hole are all integrally formed by PCB standard processing.

2. The manufacturing method of the miniature ionization vacuum sensor based on PCB technology according to claim 1, characterized in that, The cathode support plate (1), the first spacer plate (6), the gate plate (7), the second spacer plate (8), and the ion collection plate (9) are made of FR-4, ceramic PCB, polyimide PCB, PTFE high-frequency PCB, Rogers substrate, or composite insulating material.

3. The manufacturing method of the miniature ionization vacuum sensor based on PCB technology according to claim 1, characterized in that, In step S3, the vacuum-compatible surface treatment is at least one of the following: immersion nickel gold, hard gold, electroplated gold, immersion silver, immersion tin, nickel palladium gold, and anti-oxidation treatment, used to reduce the electrode oxidation rate, reduce contact resistance, and suppress the release of pollutants from the vacuum environment.

4. The manufacturing method of the miniature ionization vacuum sensor based on PCB technology according to claim 1, characterized in that, In step S3, the accelerating gate electrode of the gate plate (7) is formed by any one of the following: PCB copper foil etching mesh, electroplated thickened metal mesh, metallized through-hole array, or embedded metal mesh; the through-hole array is prepared by mechanical drilling, laser drilling, controlled depth milling, plasma opening, or punching process.

5. The manufacturing method of the miniature ionization vacuum sensor based on PCB technology according to claim 1, characterized in that, In step S5, the first spacer (6) and the second spacer (8) are PCB core boards with a center window, prepregs, ceramic insulating sheets, polyimide insulating sheets or assemblies. The thickness of the first spacer (6) limits the distance between the electron emitter (5) and the two layers of the accelerating gate electrode. The thickness of the second spacer (8) limits the distance between the accelerating gate electrode and the two layers of the ion collecting electrode (10).

6. The manufacturing method of the miniature ionization vacuum sensor based on PCB technology according to claim 1, characterized in that, In step S1, several sensor unit arrays are arranged on the same PCB panel. From step S2 to step S6, the entire process involves synchronous batch processing, assembly, baking, and electrical testing on a panel-by-panel basis. After passing the test, individual individual sensors are obtained by V-cutting, stamp hole cutting, milling, and laser cutting.

7. The manufacturing method of the miniature ionization vacuum sensor based on PCB technology according to claim 1, characterized in that, In step S6, before baking and degassing or after testing, a magnetic field unit (14) consisting of a permanent magnet, a magnetic ring, and an electromagnetic coil is installed on the outside of the ionization cavity; the magnetic field unit (14) is fixed to the outside of the sensor board through a PCB pre-reserved mounting slot, positioning hole, adhesive, and snap-fit ​​structure.

8. A miniature ionization vacuum sensor based on PCB technology, manufactured using the method described in any one of claims 1 to 7, characterized in that, The assembly includes a cathode support plate (1), a first spacer plate (6), a gate plate (7), a second spacer plate (8), and an ion collection plate (9) stacked in sequence. The cathode support plate (1) is a PCB-compatible material with an emitter connection pad (2) and an external lead-out pad (3) on it. A first metallized via (4) is provided between the emitter connection pad (2) and the external lead-out pad (3). An electron emitter (5) is fixed on the emitter connection pad (2). The first spacer plate (6) has a first cavity window. The gate plate (7) forms a PCB metallized accelerating gate electrode. The second spacer plate (8) has a second cavity window. The ion collection plate (9) has an ion collection electrode (10) and an external connecting hole (13). A magnetic field unit (14) is provided on the outside of the ion collection plate (9). The cavity windows of each layer are interconnected to form an ionization cavity. The accelerating gate electrode and the ion collection electrode (10) are connected to the external gate pad and the ion collection pad (11) through the inner PCB trace and the second metallized via (12), respectively.

9. The miniature ionization vacuum sensor based on PCB technology according to claim 8, characterized in that, The accelerating gate electrode uses a copper foil etched grid, an electroplated nickel-gold composite grid, and a metallized via array structure. The accelerating gate electrode is interconnected with the external gate pad through inner layer traces or vertical metallized vias.

10. The miniature ionization vacuum sensor based on PCB technology according to claim 8, characterized in that, The first spacer (6) and the second spacer (8) are made of at least one of PCB core board, prepreg, and ceramic insulating sheet, and the spacing tolerance of the electrode layer inside the ionization cavity is precisely controlled by the thickness tolerance of the spacer.

Images