A waterproof inductive proximity sensor based on pecvd

Abstract

The application discloses a waterproof inductive proximity sensor based on PECVD, which comprises a shell, a detection coil, a magnetic tank and a signal processing circuit board packaged in the shell, and the surfaces of the detection coil, the magnetic tank and the signal processing circuit board are covered with a multilayer composite protective layer prepared by using a plasma enhanced chemical vapor deposition process. The three-level composite protective structure of insulation of a bottom layer (a dielectric layer), barrier of a middle layer (a barrier layer) and hydrophobicity of a surface layer forms a comprehensive and three-dimensional protection system for the internal elements of the waterproof inductive proximity sensor, and solves the technical problem that a single material is difficult to simultaneously consider electrical insulation, dense barrier and hydrophobic protection.

Description

Technical Field

[0001] This invention relates to the field of inductive proximity sensor technology, and specifically to a waterproof inductive proximity sensor based on PECVD. Background Technology

[0002] An inductive proximity sensor is a non-contact position detection device based on the principle of electromagnetic induction. Its core consists of a high-frequency oscillating coil, a signal processing circuit, and an output drive unit. This sensor triggers a switch signal output by detecting changes in the equivalent inductance of the coil when a metal object approaches. Due to its advantages such as non-contact operation, no wear, fast response speed, and strong anti-interference capability, it is widely used in various fields including industrial automation and manufacturing, transportation and automotive, CNC machine tools, and machining.

[0003] In practical applications, inductive proximity sensors often need to operate for extended periods in high-temperature and high-humidity environments. Moisture can easily penetrate the sensor through gaps in the front cover, lamp holder, and housing, not only altering the magnetic field distribution at the sensor's front end and directly causing functional failure, but also inducing electrochemical corrosion on the surfaces of metal components such as coils, pads, and pins, leading to problems such as component resistance drift and electrical connection wire corrosion and breakage. Coupled with factors such as decreased magnetic permeability of magnetic materials and deterioration of the electrical environment under high-temperature conditions, the sensor is highly susceptible to malfunctions such as detection failure, abnormally increased detection distance, and disordered output signals, severely affecting its reliability and service life.

[0004] To address the waterproofing issue of inductive proximity sensors, several solutions have been disclosed in existing technologies. The mainstream solutions include potting compound encapsulation, mechanical seal structure design, and hydrophobic coating spraying. However, all of these solutions have significant technical drawbacks: First, potting compound encapsulation is limited by the physicochemical properties of the adhesive itself. Parameters such as the dielectric constant of the adhesive can alter the internal electromagnetic environment of the sensor, interfering with the normal operation of the high-frequency oscillation coil and affecting the sensor's detection accuracy and sensitivity. Second, mechanical seal structures require additional components such as sealing rings and gaskets, which not only increases the overall package size of the sensor and reduces installation compatibility but also raises production and maintenance costs. Furthermore, the sealing components are prone to aging and failure under high temperatures, making long-term sealing difficult. Third, the hydrophobic coating spraying process suffers from poor film thickness uniformity, easily forming microscopic gaps on complex curved surfaces of the sensor and between coil turns. Moisture can penetrate through these gaps, and a single-layer hydrophobic coating cannot simultaneously meet the multiple requirements of electrical insulation and moisture barrier.

[0005] Therefore, there is an urgent need to develop a waterproof inductive proximity sensor to achieve comprehensive waterproof protection for the core components inside the sensor, ensuring its long-term stable operation in high temperature and high humidity environments. Summary of the Invention

[0006] The purpose of this invention is to solve the technical problems of poor protection and low reliability of existing inductive proximity sensors in high temperature and high humidity environments, and to provide a waterproof inductive proximity sensor based on plasma enhanced chemical vapor deposition (PECVD). The PECVD process enables the waterproof function of the inductive proximity sensor, allowing it to work stably for a long time in high temperature and high humidity environments (85 ℃ / 85% RH).

[0007] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0008] A waterproof inductive proximity sensor based on plasma-enhanced chemical vapor deposition includes a front cap, a housing, a rear cap, a connecting cable, and a detection coil, a magnetic can, and a signal processing circuit board encapsulated inside the housing. The surfaces of the detection coil, the magnetic can, and the signal processing circuit board are all covered with a multi-layer composite protective layer prepared by plasma-enhanced chemical vapor deposition.

[0009] The multilayer composite protective layer consists of a dielectric layer, a barrier layer, and a hydrophobic modification layer from the inside out; wherein the dielectric layer is a silicon nitride layer or a silicon oxide layer, the barrier layer is a silicon carbonitride layer or a silicon oxynitride layer, and the hydrophobic modification layer is a fluorinated polymer layer or a fluorinated modification layer.

[0010] This invention uses PECVD process to coat the detection coil, magnetic canister and signal processing circuit board inside the sensor with a film, which can effectively prevent moisture from entering the product and significantly improve the reliability of the sensor in high temperature and high humidity environments.

[0011] Furthermore, the thickness of the dielectric layer is 50-200 nm. The dielectric layer is used to achieve electrical insulation between the coil and the magnetic can, and inside the coil, while also serving as a transitional adhesive layer for the intermediate barrier layer, enhancing the adhesion between the film layer and the substrate.

[0012] Furthermore, the thickness of the barrier layer is 100-500 nm. The barrier layer is the main barrier structure of the multilayer composite protective layer, used to block the penetration of water vapor, oxygen and corrosive media, and its density is higher than that of the dielectric layer and the hydrophobic modified layer.

[0013] Furthermore, the carbon content of the silicon carbonitride layer is 10-20%.

[0014] Furthermore, the thickness of the hydrophobic modified layer is 10-50 nm. The hydrophobic modified layer has hydrophobic and oleophobic properties, which can reduce the adhesion of water droplets on the sensor surface and reduce the deposition of contaminants on the sensing surface.

[0015] Furthermore, the fluorinated polymer layer is formed by plasma-enhanced chemical vapor deposition of a perfluoropolyether derivative.

[0016] Furthermore, the perfluoropolyether derivative is a perfluoropolyether siloxane.

[0017] Furthermore, the fluorinated modified layer is formed from fluorocarbon polymers (CFx, x=1-4) by plasma-enhanced chemical vapor deposition.

[0018] In a specific embodiment, the process parameters for plasma-enhanced chemical vapor deposition (CFx) are as follows: the reaction chamber temperature of the plasma-enhanced chemical vapor deposition equipment is set at 15-100 °C, the flow rate of the main monomer precursor gas is 50-200 sccm, hydrogen or argon can be introduced simultaneously as carrier gas and dilution gas, with a flow rate of 20-100 sccm, the stable reaction chamber pressure is 20-100 mTorr (approximately 2.7-13.3 Pa), and the applied radio frequency power is 10-200 W.

[0019] The reaction chamber temperature of the PECVD equipment is 15-300 ℃, the pressure is 20-800 mTorr, and the applied radio frequency power is 10-600 W.

[0020] Furthermore, the thickness ratio of the dielectric layer, the barrier layer, and the hydrophobic modified layer is 1:(2-5):(0.1-0.5).

[0021] Furthermore, the parameters of the plasma-enhanced chemical vapor deposition are as follows: the reaction chamber temperature of the plasma-enhanced chemical vapor deposition equipment is 15-300 ℃, the pressure is 20-800 mTorr, and the applied radio frequency power is 10-600 W.

[0022] The above-described technical solution of the present invention has the following beneficial effects:

[0023] 1. This invention uses a three-level composite protection structure consisting of an insulating bottom layer (dielectric layer), a barrier layer (interceptor layer), and a hydrophobic surface layer to form a comprehensive and three-dimensional protection system for the internal components of a waterproof inductive proximity sensor, thus solving the technical problem that a single material cannot simultaneously provide electrical insulation, dense barrier, and hydrophobic protection.

[0024] 2. The waterproof inductive proximity sensor based on PECVD provided by this invention exhibits excellent operational reliability in harsh high-temperature and high-humidity environments of 85 ℃ / 85% RH, with an insulation resistance attenuation rate of less than 10% and a detection distance drift of less than 5%. Its protective performance is significantly superior to existing single-layer or double-layer protective structures of inductive proximity sensors. Furthermore, this invention uses PECVD technology to prepare a multi-layer composite protective layer, achieving uniform conformal coverage of complex curved surfaces, inter-turn gaps, and lead bonding points of the detection coil, eliminating blind spots and ensuring precise control over the film thickness without affecting the sensor's detection sensitivity. In addition, the deposition temperature of the protective layer is below 300 ℃, preventing thermal damage to various precision components inside the sensor. It is highly compatible with existing sensor packaging processes, requiring no significant adjustments to the original production process, and possesses a solid foundation for industrial application. Attached Figure Description

[0025] Figure 1 This is a physical image of the waterproof inductive proximity sensor based on PECVD in Example 1.

[0026] Figure 2 This is a schematic diagram of the structure of the waterproof inductive proximity sensor based on PECVD in Example 1.

[0027] Figure 3 This is a schematic diagram of the internal structure of the housing of the waterproof inductive proximity sensor based on PECVD in Example 1.

[0028] Figure 4 This is a physical image of a detection coil, magnetic container, and signal processing circuit board covered with a multi-layer composite protective layer prepared by PECVD process. Detailed Implementation

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] This invention provides a waterproof inductive proximity sensor based on plasma-enhanced chemical vapor deposition, comprising a housing and a detection coil, a magnetic can, and a signal processing circuit board encapsulated inside the housing. The surfaces of the detection coil, the magnetic can, and the signal processing circuit board are all covered with a multilayer composite protective layer prepared by plasma-enhanced chemical vapor deposition.

[0031] The multilayer composite protective layer consists of a dielectric layer, a barrier layer, and a hydrophobic modification layer from the inside out; wherein the dielectric layer is a silicon nitride layer or a silicon oxide layer, the barrier layer is a silicon carbonitride layer or a silicon oxynitride layer, and the hydrophobic modification layer is a fluorinated polymer layer or a fluorinated modification layer.

[0032] PECVD is a core process in thin film preparation. This process allows for the ionization of reactive gases into plasma using radio frequency or microwave methods in a low-temperature vacuum environment, thereby depositing functional thin films on the target substrate surface. It is currently widely used in the preparation of various functional films, including hydrophilic / hydrophobic films, electrically insulating films, and waterproof films. PECVD offers significant advantages such as low deposition temperature, strong adhesion between the film and substrate, and the ability to achieve conformal coverage of complex curved surfaces without dead angles. This invention combines PECVD with a multilayer composite thin film structure and applies it to the surface of the core components inside an inductive proximity sensor. This creates an integrated protective structure that simultaneously provides electrical insulation, dense moisture barrier, and surface hydrophobicity, solving the technical problems of poor protection and low reliability of existing inductive proximity sensors in high-temperature and high-humidity environments.

[0033] In one specific embodiment of the present invention, the fabrication process of a waterproof inductive proximity sensor based on PECVD is as follows: First, pre-processing of the core components is performed, including the prefabrication of the metal detection coil, and simultaneous substrate cleaning and oxygen plasma surface activation treatment of the signal processing circuit board. Then, the prefabricated detection coil, magnetic container, and signal processing circuit board are placed as a whole (hereinafter referred to as the "to-be-deposited whole") in a PECVD apparatus for the deposition of a multilayer composite protective layer; the deposition process consists of vacuuming, introducing reactive gas, plasma excitation, and thin film deposition. After deposition, the to-be-deposited whole undergoes post-processing, consisting of low-temperature annealing and photolithography etching. Finally, the post-processed to-be-deposited whole is assembled with a metal shell, front cap, rear cap, and connecting cables to obtain the waterproof inductive proximity sensor based on PECVD.

[0034] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0035] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0036] Example 1

[0037] A waterproof inductive proximity sensor based on PECVD, as shown in the image below. Figure 1As shown, it includes a front cap, a cylindrical metal shell, a rear cap, and connecting cables. A structural diagram is shown below. Figure 2 As shown, the front end of the housing has a sensing surface, and the housing contains a detection coil, a magnetic container, and a signal processing circuit board. A schematic diagram of the structure is shown below. Figure 3 As shown;

[0038] The surfaces of the detection coil, magnetic jar, and signal processing circuit board are all covered with a multi-layer composite protective layer prepared by PECVD process, as shown in the physical image. Figure 4 As shown, from the inside out are:

[0039] Silicon nitride layer (Si3N4 thin film) with a silicon-to-nitrogen atomic ratio of 3:4 and a thickness of 100 nm;

[0040] Silicon carbonitride layer, with a carbon content of 10%-20% and a thickness of 300 nm;

[0041] Fluorinated modified layer (CFx film) with a thickness of 15 nm.

[0042] Example 2

[0043] A waterproof inductive proximity sensor based on PECVD includes a front cap, a cylindrical metal housing, a rear cap, and a connecting cable. The front end of the housing has a sensing surface, and the housing encapsulates a detection coil, a magnetic can, and a signal processing circuit board.

[0044] The surfaces of the detection coil, magnetic jar, and signal processing circuit board are all covered with a multi-layer composite protective layer prepared by PECVD process, which consists of the following layers from the inside out:

[0045] The silicon oxide layer (SiO2 thin film) has a thickness of 100 nm.

[0046] A silicon oxynitride layer, 250 nm thick;

[0047] The perfluoropolyether siloxane layer has a thickness of 20 nm.

[0048] Comparative Example 1

[0049] A waterproof inductive proximity sensor based on PECVD includes a front cap, a cylindrical metal housing, a rear cap, and a connecting cable. The front end of the housing has a sensing surface, and the housing encapsulates a detection coil, a magnetic can, and a signal processing circuit board.

[0050] The surfaces of the detection coil, magnetic jar, and signal processing circuit board are all covered with a 300nm thick silicon nitride layer prepared by PECVD process.

[0051] Comparative Example 2

[0052] A waterproof inductive proximity sensor based on PECVD includes a front cap, a cylindrical metal housing, a rear cap, and a connecting cable. The front end of the housing has a sensing surface, and the housing encapsulates a detection coil, a magnetic can, and a signal processing circuit board.

[0053] The surfaces of the detection coil, magnetic jar, and signal processing circuit board are all covered with a multi-layer composite protective layer prepared by PECVD process, which consists of the following layers from the inside out:

[0054] The silicon oxide layer (SiO2 thin film) has a thickness of 100 nm.

[0055] Fluorinated modified layer (CFx film) with a thickness of 15 nm.

[0056] Comparative Example 3

[0057] An inductive proximity sensor includes a front cap, a cylindrical metal housing, a rear cap, and a connecting cable. The front end of the housing has a sensing surface, and the housing encapsulates a detection coil, a magnetic can, and a signal processing circuit board.

[0058] The surfaces of the detection coil, magnetic can, and signal processing circuit board were not protected by PECVD process, but by traditional process: first, an acrylic conformal coating with a thickness of about 30 μm was sprayed onto the entire component, and then epoxy resin was used for overall potting.

[0059] In the above embodiments, the method for depositing Si3N4 thin films using PECVD includes the following steps:

[0060] (1) The substrate to be deposited is placed in the reaction chamber of the PECVD equipment, and the surface of the substrate is cleaned with argon plasma. The cleaning conditions are: argon flow rate 500 sccm, radio frequency power 300 W, chamber pressure 0.5 Torr, and processing time 60s. This pretreatment step is used to remove surface contaminants and activate the surface to enhance film adhesion.

[0061] (2) After cleaning, the temperature of the reaction chamber was set and stabilized at 300 °C, and the flow rates of the reaction gases were adjusted as follows: silane (SiH4) flow rate was 150 sccm, ammonia (NH3) flow rate was 750 sccm, and the gas flow rate ratio was 1:5; the pressure of the reaction chamber was stabilized at 800 mTorr (approximately 106.7 Pa), and a radio frequency power of 600 W was applied to deposit a Si3N4 thin film with a thickness of approximately 100 nm. This thin film has better protection against environments that are extremely sensitive to humidity.

[0062] In the above embodiments and comparative examples, the method for depositing SiO2 thin films by PECVD process includes the following steps:

[0063] (1) The substrate to be deposited is placed in the reaction chamber of the PECVD equipment, and the surface of the substrate is cleaned with argon plasma. The cleaning conditions are: argon flow rate 500 sccm, radio frequency power 300 W, chamber pressure 0.5 Torr, and processing time 60s. This pretreatment step is used to remove surface contaminants and activate the surface to enhance film adhesion.

[0064] (2) After cleaning, the temperature of the reaction chamber is set and stabilized at 250 °C. The flow rates of the reaction gases are adjusted as follows: the flow rate of silane (SiH4) is 200 sccm, the flow rate of nitrous oxide (N2O) is 1000 sccm, and the gas flow rate ratio is 1:5. The pressure of the reaction chamber is stabilized at 350 mTorr (about 46.7 Pa). Radio frequency power at a frequency of 13.56 MHz is applied with a power value of 400 W to deposit a uniform and dense SiO2 film with a thickness of about 100 nm.

[0065] Testing revealed that the SiO2 film provides good step coverage for the sensor coil, exhibits low compressive stress (approximately -150 MPa), and has a water contact angle greater than 80°. After 96 hours of accelerated aging testing at 85 °C and 85% relative humidity, the sensor with the deposited film showed a change in inductance of less than 1%, demonstrating excellent waterproof and moisture-proof performance.

[0066] In the above embodiments and comparative examples, the method for depositing CFx thin films by PECVD process includes the following steps:

[0067] (1) The substrate to be deposited is placed in the reaction chamber of the PECVD equipment, and the surface of the substrate is cleaned with argon plasma. The cleaning conditions are: argon flow rate 500 sccm, radio frequency power 300 W, chamber pressure 0.5 Torr, and processing time 60s. This pretreatment step is used to remove surface contaminants and activate the surface to enhance film adhesion.

[0068] (2) After cleaning, the temperature of the reaction chamber was set and stabilized at 80 °C (low-temperature deposition helps retain fluorocarbon groups and obtain lower surface energy). Octafluorocyclobutane (C4F8) was used as the main monomer precursor gas with a flow rate of 100 sccm. Hydrogen was introduced as a carrier gas and dilution gas with a flow rate of 50 sccm to adjust the plasma chemical environment and the degree of crosslinking of the film. The pressure of the reaction chamber was stabilized at 50 mTorr. Lower pressure helps to form a smoother and more uniform polymer film. The radio frequency power was 50 W. Since fluorocarbon monomers are easily dissociated under high-energy plasma, a lower power was used to maintain the polymerization reaction as the main reaction rather than the etching reaction, and a CFx film with a thickness of about 15 nm was deposited. The CFx film deposited by PECVD process has a chemical structure similar to polytetrafluoroethylene (PTFE). Its surface water contact angle can be as high as 110° or even 120°, exhibiting excellent hydrophobicity and anti-adhesion properties.

[0069] Test Example 1

[0070] Initial performance benchmark tests, high-temperature and high-humidity accelerated aging tests at 85℃ / 85% RH, and post-aging performance retests were conducted on the PECVD-based waterproof inductive proximity sensors of Examples 1-2 and Comparative Examples 1-2, as well as the inductive proximity sensor of Comparative Example 3. The test methods are as follows:

[0071] 1. Initial performance benchmark test

[0072] (1) Visual inspection: Use a microscope to inspect the sensor surface to confirm that it is clean, free of scratches and obvious visual defects.

[0073] (2) Insulation resistance measurement: Connect the electrodes of the insulation resistance tester to the power / signal terminals of the sensor and the metal casing (grounding terminal) respectively, apply a DC 24V test voltage, and record the initial insulation resistance value R_initial after the value stabilizes.

[0074] (3) Water contact angle measurement: Fix the sensor so that the sensing surface is horizontal and facing upward. Use a micro-syringe to drop 2-4 μL of ultrapure water into the center of the sensing surface. Collect the water droplet shape image through the contact angle measuring instrument and calculate the initial water contact angle θ_initial using the matching software.

[0075] (4) Detection distance measurement: Install the sensor on the test bench and connect it to the rated working voltage. Slowly bring the standard metal target object close to the sensing surface along the sensor axis. When the sensor output signal switches, record the distance between the target object and the sensing surface. Repeat the measurement multiple times and take the average value to obtain the initial detection distance S_initial.

[0076] 2. High temperature and high humidity accelerated aging test

[0077] The sensor that has completed the initial performance test was placed in a constant temperature and humidity test chamber. The test conditions were set to a temperature of 85℃ and a relative humidity of 85% RH, and it was run continuously for 1000 hours. During the test, the sensor was not powered on, but was powered on once every 24 hours and its basic functional status was monitored.

[0078] 3. Performance retesting after aging

[0079] (1) Sensor recovery: After the aging test, the sensor is removed from the test chamber and placed in a standard laboratory environment of 25 ℃ and 50% RH for at least 1 hour. Subsequent tests are carried out after the sensor recovers to room temperature.

[0080] (2) Visual inspection: Use a microscope to inspect the sensor sensing surface again to observe whether there are any abnormal phenomena such as bubbling, cracking, or coating peeling.

[0081] (3) Performance parameter retest: Strictly follow the same method, equipment and operation procedure as the initial performance test above, measure and record the final value of insulation resistance R_final, final value of water contact angle θ_final and final value of detection distance S_final for each sample.

[0082] 4. Data Analysis and Acceptance Criteria

[0083] Calculate the retention rate or decay rate of each performance indicator, and determine whether the sample is qualified according to the following standards:

[0084] Insulation resistance retention rate: The calculation formula is (R_final / R_initial)×100%, and the pass criterion is a retention rate >90%;

[0085] Water contact angle: Directly read the final test value θ_final, the pass criterion is contact angle >110°;

[0086] Detection distance attenuation rate: The calculation formula is [(S_initial-S_final) / S_initial]×100%, and the pass criterion is attenuation rate <5%.

[0087] The test results are as follows:

[0088] After 1000 hours of continuous operation in a high temperature and high humidity environment of 85 ℃ / 85% RH, the PECVD-based waterproof inductive proximity sensor in Examples 1-2 still maintains an insulation resistance rate of more than 90%, a water contact angle of more than 110°, and a detection distance attenuation of less than 5%. All performance indicators meet the IPX8 waterproof rating requirements.

[0089] The waterproof inductive proximity sensor based on PECVD in Comparative Example 1 showed a decrease in insulation resistance of >50% and the appearance of localized corrosion spots after 500 hours in an environment of 85℃ / 85%RH. The waterproof inductive proximity sensor based on PECVD in Comparative Example 2 showed a decrease in insulation resistance of >30% after 500 hours of continuous operation in a high temperature and high humidity environment of 85℃ / 85%RH. This indicates that without a barrier layer, moisture can still penetrate through the micropores of the silicon nitride layer, making long-term reliable protection impossible.

[0090] The waterproof inductive proximity sensor in Comparative Example 3 showed an insulation resistance decrease of >30% after 500 hours in an environment of 85℃ / 85%RH, a significant increase in sensor response time, and an attenuation of detection distance of about 8%, failing to meet the IPX8 waterproof rating requirements.

[0091] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art should understand that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A waterproof inductive proximity sensor based on plasma-enhanced chemical vapor deposition, comprising a front cap, a housing, a rear cap, a connecting cable, and a detection coil, a magnetic container, and a signal processing circuit board encapsulated within the housing, characterized in that, The surfaces of the detection coil, magnetic can, and signal processing circuit board are all covered with a multi-layer composite protective layer prepared using plasma-enhanced chemical vapor deposition. The multilayer composite protective layer consists of a dielectric layer, a barrier layer, and a hydrophobic modification layer from the inside out; wherein the dielectric layer is a silicon nitride layer or a silicon oxide layer, the barrier layer is a silicon carbonitride layer or a silicon oxynitride layer, and the hydrophobic modification layer is a fluorinated polymer layer or a fluorinated modification layer.

2. The waterproof inductive proximity sensor according to claim 1, characterized in that, The thickness of the dielectric layer is 50-200 nm.

3. The waterproof inductive proximity sensor according to claim 1, characterized in that, The thickness of the barrier layer is 100-500 nm.

4. The waterproof inductive proximity sensor according to claim 1, characterized in that, The carbon content of the silicon carbonitride layer is 10-20%.

5. The waterproof inductive proximity sensor according to claim 1, characterized in that, The thickness of the hydrophobic modified layer is 10-50 nm.

6. The waterproof inductive proximity sensor according to claim 1, characterized in that, The fluorinated polymer layer is formed by plasma-enhanced chemical vapor deposition of a perfluoropolyether derivative.

7. The waterproof inductive proximity sensor according to claim 6, characterized in that, The perfluoropolyether derivative is a perfluoropolyether siloxane.

8. The waterproof inductive proximity sensor according to claim 1, characterized in that, The fluorinated modified layer is formed by plasma-enhanced chemical vapor deposition of fluorocarbon polymers.

9. The waterproof inductive proximity sensor according to claim 1, characterized in that, The thickness ratio of the dielectric layer, the barrier layer, and the hydrophobic modified layer is 1:(2-5):(0.1-0.5).

10. The waterproof inductive proximity sensor according to claim 1, characterized in that, The process parameters for plasma-enhanced chemical vapor deposition are as follows: the reaction chamber temperature of the plasma-enhanced chemical vapor deposition equipment is 15-300℃, the pressure is 20-800 mTorr, and the applied radio frequency power is 10-600 W.

Images