Arc ion plating device with target material rotation and magnetic field coupling

Abstract

The invention provides a target material rotation and magnetic field coupling arc ion plating device which is matched with magnetic fluid multistage sealing and a double-circulation water cooling system through the design of high-speed rotation of a target material and dynamic coupling of a magnetic field of a static permanent magnet. The core problems of large particle pollution, low target material utilization rate, poor high-temperature working condition stability and the like in a traditional arc ion plating process are systematically solved. By combining internal and external independent water cooling channels, the surface temperature of the target material is stabilized below the working range, and the transmission system temperature rise is small; the modularized magnet and gear transmission design further reduces energy consumption and maintenance cost, and the film thickness uniformity is improved through rotating speed-magnetic field-cooling intelligent regulation and control. And a high-reliability industrial solution is provided for high-performance coating.

Description

Technical Field

[0001] The present invention relates to the technical field of vacuum coating, and in particular to an arc ion plating device in which target material rotation is coupled with a magnetic field. Background Art

[0002] Arc ion plating is a physical vapor deposition (PVD) technology widely used in surface treatment, with advantages such as high deposition rate, dense film layer, and strong adhesion. However, despite the excellent performance of arc ion plating technology in the industrial field, its application is still limited by some key issues.

[0003] The presence of large particles is a major challenge in arc ion plating technology. These particles can severely impact the performance and service life of coatings and thin films, becoming a bottleneck hindering the further development of arc ion plating technology. To address this issue, magnetic filtration technology is currently being used to improve coating quality by removing large particles during the plasma transmission process.

[0004] However, magnetic filtration technology can only process large particles after they are generated, which cannot fundamentally solve the problem of large particles. It also leads to problems such as reduced target material utilization and increased difficulty in equipment cleaning. Therefore, a better solution is urgently needed to solve this problem.

[0005] Vacuum arc discharge is essentially a series of arc events, where the overall arc behavior is determined by the motion of the cathode spot and arc root. The sequential ignition and extinction of adjacent arc spots constitutes arc spot motion. Research has shown that arc spot aggregation and slow motion are the primary causes of large particles on the cathode target surface. Therefore, effectively controlling the motion characteristics of arc spots on the target surface to prevent them from stagnating or moving too slowly has become a key technical challenge in improving arc ion plating process stability, film uniformity, and target utilization.

[0006] The existing devices for realizing rotating magnetic fields are relatively complex in structure, high in cost and difficult to promote. Summary of the Invention

[0007] In a first aspect of the present disclosure, there is provided an arc ion plating device in which target rotation is coupled with a magnetic field, comprising:

[0008] The target (1) is arranged at the center of the device;

[0009] A shielding cover (2) is coaxially sleeved on the outside of the target material and completely covers the target material;

[0010] An annular magnet assembly (3) is coaxially arranged outside the shielding cover and comprises two semicircular arc-shaped permanent magnets with opposite magnetic poles, wherein the arc range of the semicircular arc-shaped permanent magnets is 30° to 160°;

[0011] A magnetic conductive ring (4) is coaxially wrapped around the outer side of the magnet assembly to form a closed magnetic circuit;

[0012] A power transmission system comprises a first gear (6a) and a second gear (6b) meshing with each other, wherein the first gear is rigidly connected to the target material via a transmission shaft, and the second gear is connected to an output shaft of a driving motor (7);

[0013] A magnetic fluid sealing assembly (5) is disposed below the target material and is sealed and connected to the transmission shaft;

[0014] A water cooling system (8) is integrated into the transmission shaft and forms a heat conduction path with the target material;

[0015] Among them, the target material, shielding cover, annular magnet assembly and magnetic conductive ring constitute the working assembly inside the vacuum chamber, the power transmission system, drive motor and water cooling system constitute the driving assembly outside the vacuum chamber, and the magnetic fluid sealing assembly realizes the sealing isolation between the inside and outside of the vacuum chamber.

[0016] In combination with the first aspect, the curvature of the semicircular permanent magnet is positively correlated with the target rotation speed, specifically satisfying:

[0017] When the target rotation speed is 3000-5000rpm, the magnet arc is 30°-60°;

[0018] When the target rotation speed is 6000-8000rpm, the magnet arc is 60°-90°;

[0019] When the target rotation speed is 9000-10000rpm, the magnet arc is 90°-160°.

[0020] In combination with the first aspect, the target material (1) is made of any conductive material selected from graphite, titanium or copper, and has a surface roughness Ra≤0.8 μm and a purity≥99.95%.

[0021] In combination with the first aspect, the shielding cover (2) is made of non-magnetic material, the distance between its inner surface and the outer surface of the target is 5-15 mm, and the non-magnetic material includes titanium alloy or stainless steel with surface passivation treatment, and the passivation layer thickness is 2-5 μm.

[0022] In combination with the first aspect, the annular magnet assembly (3) is made of neodymium iron boron permanent magnet material, the surface magnetic induction intensity of which is 0.5-1.2T, the Curie temperature is ≥350°C, and the contact surface of the two semicircular arc-shaped permanent magnets is provided with a magnetic conductive gap of 0.1-0.5mm.

[0023] In combination with the first aspect, the magnetic permeability of the magnetic ring (4) is ≥5000, the matching tolerance between its inner diameter and the outer diameter of the magnet assembly is H7 / g6, and the material is selected from any one of iron-nickel alloy, silicon steel or nanocrystalline soft magnetic alloy.

[0024] In combination with the first aspect, the gear module of the power transmission system is 2-4, the transmission ratio is 1:1 to 1:3, and the meshing clearance of the gear pair is controlled within the range of 0.05-0.15 mm by the eccentric sleeve adjustment mechanism.

[0025] In combination with the first aspect, the magnetic fluid sealing component (5) comprises a multi-stage magnetic pole structure, the sealing pressure of each stage is ≥0.15MPa, the overall pressure difference is ≥1.5MPa, and the applicable temperature range is -50°C to 200°C.

[0026] In combination with the first aspect, the water cooling system (8) adopts a double-circulation cooling structure, comprising:

[0027] Internal circulation channel, directly cools the evaporation surface of the target material, with a coolant flow rate of 5-15L / min;

[0028] External circulation channel, cooling transmission system bearings, coolant flow rate is 2-8L / min;

[0029] The inner and outer circulation channels are sealed and connected via a rotary joint.

[0030] Beneficial Effects: The present disclosure provides an arc ion plating device that couples target rotation with a magnetic field. This device, through a design that dynamically couples the high-speed rotation of the target with the magnetic field of a static permanent magnet, combined with a multi-stage magnetic fluid seal and a dual-circulation water cooling system, systematically addresses core challenges encountered in conventional arc ion plating processes, such as large particle contamination, low target utilization, and poor stability under high-temperature conditions. Combined with independent internal and external water cooling channels, the target surface temperature is stabilized below the operating range, minimizing the temperature rise of the transmission system. The modular magnet and gear transmission design further reduces energy consumption and maintenance costs, while improving film thickness uniformity through intelligent speed-magnetic field-cooling control. This provides a highly reliable industrialized solution for high-performance coatings. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a three-dimensional diagram of an arc ion plating device with target rotation and magnetic field coupling according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0032] Exemplary embodiments are described in detail herein, with examples illustrated in the accompanying drawings. When the following description refers to the drawings, identical numerals in different drawings represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with the present disclosure.

[0033] The terms used in the embodiments of the present disclosure are for the purpose of describing specific embodiments only and are not intended to limit the embodiments of the present disclosure. The singular forms "a," "the," and "the" used in the embodiments of the present disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0034] like Figure 1 FIG. 1 is a perspective view of an arc ion plating device with target rotation and magnetic field coupling according to an embodiment of the present disclosure, comprising:

[0035] The target (1) is arranged at the center of the device;

[0036] A shielding cover (2) is coaxially sleeved on the outside of the target material and completely covers the target material;

[0037] An annular magnet assembly (3) is coaxially arranged outside the shielding cover and comprises two semicircular arc-shaped permanent magnets with opposite magnetic poles, wherein the arc range of the semicircular arc-shaped permanent magnets is 30° to 160°;

[0038] A magnetic conductive ring (4) is coaxially wrapped around the outer side of the magnet assembly to form a closed magnetic circuit;

[0039] A power transmission system comprises a first gear (6a) and a second gear (6b) meshing with each other, wherein the first gear is rigidly connected to the target material via a transmission shaft, and the second gear is connected to an output shaft of a driving motor (7);

[0040] A magnetic fluid sealing assembly (5) is disposed below the target material and is sealed and connected to the transmission shaft;

[0041] A water cooling system (8) is integrated into the transmission shaft and forms a heat conduction path with the target material;

[0042] Among them, the target material, shielding cover, annular magnet assembly and magnetic conductive ring constitute the working assembly inside the vacuum chamber, the power transmission system, drive motor and water cooling system constitute the driving assembly outside the vacuum chamber, and the magnetic fluid sealing assembly realizes the sealing isolation between the inside and outside of the vacuum chamber.

[0043] Specifically, the core principle of Arc Ion Plating (AIP) is to evaporate the target material (such as titanium, graphite, etc.) through arc discharge, form plasma, and deposit a film on the surface of the substrate.

[0044] This device realizes the "virtual rotation" of the magnetic field on the target surface through the coupling design of mechanical rotating target + static permanent magnet.

[0045] The motor 7 rotates, driving the transmission shaft 6a through gear 6b. A magnetic fluid seal assembly 5 is attached to the top of the transmission shaft. This seal assembly 5 fits over the lower extension of the target 1, ensuring a rigid connection. Consequently, the rotation of the motor 7 ultimately drives the target 1 to rotate at high speed, forcing the arc spot to move tangentially along the target surface due to centrifugal force.

[0046] In the water cooling system (8), it is connected to an external water pump via a rotary joint (transverse joint), and the coolant flows through the internal ring pipe to remove the heat of the cooling mechanical parts.

[0047] The shielding cover 2 is placed on the outside of the target material 1, and the distance between the two is 5-15 mm, which can be adjusted by a gasket.

[0048] The shielding cover 2 is fixed to the vacuum chamber wall with bolts, and a plasma escape hole (aperture 1-3mm) is opened on the side wall. The annular magnet assembly 3 (two semicircular magnets with N / S poles facing each other) and the magnetic ring (4) are installed close to the outer wall of the shielding cover and fixed with screws reserved at the bottom.

[0049] When the target rotates, the position of the surface relative to the magnetic field changes periodically, which is equivalent to the "reverse rotation" of the magnetic field, generating a dynamic Lorentz force.

[0050] Applying negative high voltage (-100 to -200V) to the target triggers arc discharge, generating high-temperature plasma (temperature > 2000°C) on the target surface.

[0051] Arc spots (about 10-100 μm in diameter) are randomly generated on the target surface.

[0052] The target rotates at high speed, forcing the spot to move tangentially.

[0053] The evaporated particles (metal or carbon ions) fly towards the substrate under the action of the electric field, depositing to form a dense film layer. The magnetic field constrains the plasma diffusion, and the film thickness non-uniformity is less than ±5%.

[0054] Beneficial Effects: This device achieves high-speed target rotation through gear transmission. Combined with the spatial distribution characteristics of a static magnetic field, it replaces complex electromagnetic control with a low-cost mechanical structure, fundamentally resolving the problems of large particle contamination and low target utilization in arc coating. Its design culminates in the seamless coupling of physical motion (rotation) and magnetic field action (Lorentz force), providing an efficient and reliable solution for industrial coating.

[0055] Furthermore, the curvature of the semicircular permanent magnet is positively correlated with the target rotation speed, specifically satisfying:

[0056] When the target rotation speed is 3000-5000rpm, the magnet arc is 30°-60°;

[0057] When the target rotation speed is 6000-8000rpm, the magnet arc is 60°-90°;

[0058] When the target rotation speed is 9000-10000rpm, the magnet arc is 90°-160°.

[0059] Specifically, the movement rate of the arc spot is determined by the centrifugal force generated by the rotation of the target and the Lorentz force exerted by the magnetic field. When the target rotation speed increases, the tangential speed of the spot increases. If the magnetic field action area (i.e., the magnet curvature) is too small, the spot may quickly move out of the effective action range of the magnetic field, resulting in the interruption of the driving force. Therefore, the magnet curvature needs to be expanded as the rotation speed increases to ensure that the spot is always within the magnetic field coverage area. For example:

[0060] Low speed range (3000-5000rpm): The tangential speed of the spot is low, and a small arc magnet of 30°-60° can provide a continuous magnetic field. At this time, the magnetic field coverage area is narrow, but the spot moves slowly, and the magnetic field can still effectively exert thrust.

[0061] High speed range (9000-10000rpm): The tangential speed of the spots is greatly increased, and a large arc magnet of 90°-160° is required to expand the range of the magnetic field to prevent the spots from losing driving force after leaving the magnetic field area, resulting in a drop in speed.

[0062] The electrical conductivity, thermal conductivity and arc spot behavior of different target materials vary significantly, so the combination of magnetic field arc and rotation speed needs to be adjusted accordingly:

[0063] High-resistance materials (such as graphite): The arc spot migration resistance is large, requiring a higher rotation speed (9000-10000rpm) and a superimposed wide arc magnetic field (90°-160°). By enhancing the centrifugal force and expanding the range of the magnetic field, the spot movement is dual-driven.

[0064] Good conductor materials (such as copper): The spots are easily driven by the Lorentz force, and only a relatively low rotation speed (3000-5000rpm) and a small arc magnetic field (30°-60°) are required to achieve effective control while reducing energy consumption.

[0065] Medium conductive materials (such as titanium): Use a medium speed of 6000-8000rpm and a medium arc magnet of 60°-90° to balance driving force and energy consumption.

[0066] The closed magnetic circuit design of the magnetic ring makes the magnetic field lines concentrated on the target surface, and the magnetic induction intensity is increased to 0.5-1.2T (the traditional open magnetic circuit is only 0.2-0.5T). When the curvature of the magnet increases, the magnetic ring maintains the effectiveness of the magnetic field by:

[0067] Reduce magnetic leakage: The closed magnetic circuit constrains the divergence of magnetic flux lines. Even if the magnet arc is extended to 160°, the target surface can still maintain a high-intensity magnetic field (≥0.8T).

[0068] Homogenized magnetic field gradient: The wide arc magnet is combined with the magnetic ring to make the magnetic field intensity distribution on the target surface more uniform (fluctuation < ±10%), avoiding insufficient local driving force.

[0069] Furthermore, the target material (1) is made of any conductive material selected from graphite, titanium or copper, and has a surface roughness Ra≤0.8 μm and a purity≥99.95%.

[0070] Specifically, graphite, titanium, and copper targets correspond to different coating requirements, and their electrical conductivity, thermal conductivity, and arc spot behavior differ significantly:

[0071] Graphite targets: They possess negative temperature coefficients of resistance, making initial arc spot formation difficult. However, once ignited, they can maintain a stable, high-energy plasma. Their high melting point (3650°C) and low sputtering rate make them suitable for the preparation of ultra-hard carbon-based coatings (such as diamond-like carbon films). However, high rotation speeds (9,000-10,000 rpm) and wide-arc magnetic fields (90°-160°) are required to overcome spot migration resistance.

[0072] Titanium target: medium conductivity (resistivity 4.2×10 -7 Ω·m) and high thermal conductivity (21.9W / m·K). The arc spots are easily driven by magnetic fields and are suitable for medium-speed coating (6000-8000rpm), such as the preparation of corrosion-resistant TiN or TiAlN coatings.

[0073] Copper target: excellent conductivity (resistivity 1.7×10 -8 Ω·m) and ductility, the arc spot movement speed is naturally faster, suitable for high thermal conductivity film deposition at low speed (3000-5000rpm), such as heat dissipation coating of electronic components.

[0074] The three types of materials cover the conductive spectrum from insulators to good conductors, and flexible process adaptation can be achieved by adjusting device parameters (magnetic field curvature, rotation speed).

[0075] The surface roughness of the target directly affects the initial distribution uniformity and motion trajectory stability of the arc spot:

[0076] Microtopography optimization: Through precision grinding (diamond wheel) and chemical mechanical polishing (CMP), the surface roughness is controlled to Ra ≤ 0.8μm (equivalent to mirror-grade finish), eliminating micron-level protrusions and pits. This flat surface reduces the random jumping of arc spots and forces them to move regularly along the direction of the magnetic field.

[0077] Suppressing local hot spots: When the roughness is too high (Ra>1.6μm), the electric field concentrates at the micro-protrusions on the surface, easily forming fixed discharge points, causing the local molten pool depth to exceed the standard (>50μm) and produce micron-sized droplets. Surfaces with Ra≤0.8μm can reduce the dispersion of arc spot distribution by more than 60% (experimental data).

[0078] Insufficient target purity will introduce impurity ionization interference and destroy plasma stability:

[0079] Impurity ionization effect: When the target material contains light element impurities such as oxygen and nitrogen (content > 0.05%), the impurity atoms are preferentially ionized in the arc to form a low-energy ion flow, which interferes with the directional migration of the main material plasma and causes the film composition to deviate from the stoichiometric ratio (such as the N / Ti ratio fluctuation in TiN > 15%).

[0080] Arc stability: High-purity materials (≥99.95%) can reduce arcing caused by impurities, reducing discharge current fluctuations from the traditional ±20% to within ±5%.

[0081] Grain boundary optimization: High-purity metal targets have low impurity content at the grain boundaries and uniform grain size (10-50μm). The arc extension speed along the grain boundaries is more consistent, thus avoiding abnormal ablation at the grain boundaries.

[0082] Furthermore, the shielding cover (2) is made of non-magnetic material, and the distance between its inner surface and the outer surface of the target material is 5-15 mm. The non-magnetic material includes titanium alloy or stainless steel with surface passivation treatment, and the passivation layer thickness is 2-5 μm.

[0083] Specifically, the shield is made of non-magnetic material, with the inner surface of the shield limited to 5-15mm from the outer surface of the target, and the passivation layer thickness specified to be 2-5μm. This core solution is designed based on the comprehensive requirements of plasma confinement efficiency, magnetic field interference suppression, and long-term equipment stability. This technology achieves precise control of plasma behavior during arc ion plating by synergistically optimizing material properties, geometric dimensions, and surface treatment, thereby improving coating quality and extending equipment life.

[0084] The shield must simultaneously fulfill the dual functions of magnetic field isolation and plasma confinement. If a magnetically conductive material (such as ordinary steel) is used, the magnetic flux lines of the external magnetic field will be largely absorbed by the shield, causing the magnetic field intensity on the target surface to attenuate by more than 50% (experimental data), significantly weakening the driving force of the arc spot. Therefore, titanium alloy (such as Ti-6Al-4V) or passivated stainless steel (such as 316L) is selected as the shield material:

[0085] Titanium alloy: Inherently non-magnetic (magnetic permeability μ≈1.00005), with excellent high-temperature strength (yield strength ≥300MPa at 600°C) and corrosion resistance, can be directly exposed to arc plasma environment without additional coating.

[0086] Passivated stainless steel: A 2-5 μm thick chromium oxide passivation layer is formed on the surface through an acid pickling-passivation process (such as treatment with a nitric acid-hydrofluoric acid mixture). This reduces the magnetic permeability from its original value of μ≈200 to μ≈1.2, while also improving arc sputtering resistance. Passivation layer thicknesses below 2 μm provide insufficient protection, while thicknesses above 5 μm can lead to cracking and flaking (due to thermal expansion coefficient mismatch).

[0087] The distance design between the inner wall of the shield and the target surface needs to balance the plasma confinement effect and heat load management:

[0088] Lower limit 5mm: If the spacing is less than 5mm, the mechanical vibration of the target during rotation (amplitude ≤ 0.02mm) may cause collision with the shield, and the plasma plume may be over-compressed, causing the local gas pressure to rise (> 0.1Pa), increasing the probability of large particle generation.

[0089] Upper limit 15mm: If the spacing is greater than 15mm, the plasma confinement effect is weakened, and the proportion of metal vapor diffusing to the vacuum chamber wall increases to 30% (ideal value <10%), resulting in a decrease in target material utilization. Experiments show that when the spacing is 10mm, the plasma density reaches a peak (≈10 18 m -3 ), the coating rate is increased by 15%.

[0090] The radial expansion of the target material can reach 0.1-0.3mm (graphite target) when working at high temperature. The spacing design needs to reserve expansion margin to avoid hot contact.

[0091] The passivation treatment of stainless steel shielding covers includes the following core functions:

[0092] Suppress secondary discharge: Passivation layer (mainly Cr2O3) resistivity>10 6 Ω·m, blocking the conductive path between the shield and the plasma, preventing parasitic arcs from forming on the shield wall. Without passivation, random discharge points may form on the shield surface, interfering with the stability of the main arc.

[0093] Reduce metal contamination: The passivation layer blocks the contact between the stainless steel substrate (Fe, Ni) and the plasma, reducing the impurity content of the coating (such as Fe ions) from 500ppm in traditional designs to <50ppm (mass spectrometry analysis data).

[0094] Sputtering corrosion resistance: The hardness of the passivation layer (HV 800-1000) is significantly higher than that of the stainless steel substrate (HV 200). The sputtering rate is reduced by 60% under ion bombardment, and the service life is extended from 500 hours to 2000 hours.

[0095] Titanium alloy shield: suitable for high frequency and high power processes (such as graphite target coating), its thermal shock resistance (ΔT = 1000 ° C cycle times > 500 times) and lightweight (density 4.5g / cm 3 ) has significant advantages, but the cost is 3-5 times that of stainless steel.

[0096] Passivated stainless steel shield: more economical and suitable for medium and low power scenarios (such as copper target coating), but the integrity of the passivation layer needs to be checked regularly (ultrasonic testing every 200 hours), and local damage requires online recoating (sol-gel method).

[0097] The shielding cover, the magnet assembly (3) and the magnetic ring (4) together form a composite electromagnetic shielding system:

[0098] Magnetic field isolation: The non-magnetic shield blocks the external magnetic flux lines from diffusing to the vacuum chamber wall, increasing the magnetic field strength on the target surface by 20%-30% (compared to the working condition without a shield).

[0099] Plasma confinement: The annular slit structure formed between the inner wall of the shield and the target material limits the radial diffusion of the plasma through viscous resistance, allowing it to be sprayed axially to the substrate area, improving the coating uniformity to within ±5%.

[0100] Beneficial effects: This technical solution achieves efficient regulation of plasma behavior through systematic design of materials, structures and surface states, providing key guarantees for the stability and repeatability of the arc ion plating process.

[0101] Furthermore, the annular magnet assembly (3) is made of neodymium iron boron permanent magnet material, the surface magnetic induction intensity of which is 0.5-1.2T, the Curie temperature is ≥350°C, and the contact surface of the two semicircular arc-shaped permanent magnets is provided with a magnetic conductive gap of 0.1-0.5mm.

[0102] Specifically, the annular magnet assembly utilizes neodymium iron boron (NdFeB) permanent magnets, with a surface magnetic induction intensity limited to 0.5-1.2T and a Curie temperature ≥350°C. A 0.1-0.5mm magnetic gap is established between the contact surfaces of the two semicircular permanent magnets. This design is based on a comprehensive consideration of the magnetic field strength requirements, high-temperature stability, and magnetic circuit optimization in the arc ion plating process. Through the deep coupling of material properties, magnetic pole layout, and mechanical structure, this solution achieves efficient control of arc spot motion while ensuring the long-term reliability of the magnet assembly under extreme operating conditions.

[0103] As a third-generation rare earth permanent magnet, NdFeB has high magnetic energy product (≥40MGOe) and coercivity (≥20kOe), which can provide a high-intensity magnetic field in a small volume, meeting the target surface magnetic induction intensity requirement of 0.5-1.2T. The selection criteria for specific grades (such as N35SH, N45SH, and N52SH) are as follows:

[0104] High coercive force (Hcj ≥ 25kOe): Prevents the reverse magnetic field during arc discharge from causing demagnetization of the magnet. Experiments show that when the surface temperature of the magnet reaches 200°C instantaneously (caused by thermal radiation in the arc zone), NdFeB with Hcj ≥ 25kOe can still maintain a magnetic induction intensity attenuation of < 5%.

[0105] High temperature stability: grades with a Curie temperature ≥ 350°C (such as N35SH) can operate for a long time at a continuous operating temperature of 180°C (the Curie temperature of traditional magnets is about 310°C), avoiding irreversible loss of magnetic properties due to thermal radiation from the target material.

[0106] Corrosion resistance: The magnet surface is coated with nickel-copper-nickel multi-layer plating (thickness ≥ 20μm) to block the corrosion of metal vapor and moisture in the vacuum chamber, with a service life of > 10,000 hours.

[0107] The magnetic field strength on the target surface needs to balance the arc spot driving force and the plasma confinement effect:

[0108] Lower limit 0.5T: If the magnetic field strength is less than 0.5T, the Lorentz force is insufficient to overcome the spot migration resistance of high-resistance target materials such as graphite, and the spot speed is less than 3m / s, resulting in a large particle density of more than 10 3 Pieces / mm 2 .

[0109] Upper limit 1.2T: When the magnetic field strength is greater than 1.2T, the plasma is over-confined, the axial diffusion of evaporated particles is hindered, the coating rate drops by more than 30%, and the volume and cost of the magnet increase significantly.

[0110] Gradient distribution control: Through the closed magnetic circuit design of the magnetic ring (4), the magnetic field intensity on the target surface is distributed in a gradient from the center to the edge (0.5T at the center and 1.2T at the edge), forcing the arc spot to migrate to the high magnetic field area to avoid excessive ablation of the edge.

[0111] The magnetic gap set between the contact surfaces of the two semicircular arc magnets is the key to magnetic circuit optimization and thermal expansion compensation:

[0112] Magnetic circuit impedance adjustment: A gap that is too small (<0.1mm) will increase magnetic flux leakage between the poles, reducing the effective magnetic field strength by >15%. A gap that is too large (>0.5mm) will result in excessive magnetic resistance, preventing the magnetic field lines from forming a closed loop. A gap of 0.1-0.5mm allows the magnetic flux lines to be concentrated across the target surface, increasing the magnetic field utilization to over 90%.

[0113] Thermal expansion tolerance: The working temperature of the magnet can reach 180℃, and the thermal expansion coefficient of NdFeB is 1.2×10 -6 / ℃, the radial expansion of the semicircular magnet (radius 150mm) is about 0.1mm. When the gap is designed to be 0.3mm, it can completely absorb the thermal deformation and avoid the magnet cracking caused by mechanical stress.

[0114] Assembly tolerance compensation: The gap allows an assembly error of ±0.05mm to ensure the centration of the magnet module during rapid replacement and avoid magnetic field distribution distortion.

[0115] The Curie temperature (≥350°C) and temperature coefficient (αBr≈-0.12% / °C) of NdFeB together ensure high temperature stability:

[0116] Short-term tolerance: During arc discharge, the transient temperature of the target surface is greater than 2000°C, but the temperature of the magnet surface is less than or equal to 180°C (infrared temperature measurement data) due to the heat insulation design of the shielding cover (2). At this time, the magnetic induction intensity only decreases by about 8%.

[0117] Long-term stability: After 1000 hours of continuous operation at 180°C, the open-circuit magnetic flux attenuation rate of the magnet is less than 3% (traditional magnets are greater than 10%), meeting industrial-grade life requirements.

[0118] Failure protection: If the temperature exceeds 250°C unexpectedly, the silicon steel material (Curie temperature 740°C) of the magnetic ring (4) can still maintain partial magnetic circuit closure to avoid complete collapse of the magnetic field.

[0119] Furthermore, the magnetic permeability of the magnetic ring (4) is ≥5000, the matching tolerance between its inner diameter and the outer diameter of the magnet assembly is H7 / g6, and the material is selected from any one of iron-nickel alloy, silicon steel or nanocrystalline soft magnetic alloy.

[0120] Specifically, the magnetic permeability of the magnetic ring is required to be ≥5000, the inner diameter and the outer diameter of the magnet assembly adopt an H7 / g6 tolerance, and the material is limited to iron-nickel alloy, silicon steel, or nanocrystalline soft magnetic alloy. This key technical solution was developed based on multi-dimensional considerations of magnetic circuit closure efficiency, thermomechanical stability, and process economy. By synergistically optimizing the electromagnetic properties of the material and mechanical precision, this design achieves efficient utilization of magnetic field energy and long-term reliable operation of the device, fundamentally solving the problems of magnetic leakage and magnetic field attenuation in traditional open magnetic circuits.

[0121] The magnetic ring is the core component of the magnetic circuit closure. Its magnetic permeability directly determines the magnetic field energy utilization rate:

[0122] Magnetic field line confinement: Materials with a magnetic permeability of ≥5000 (such as Fe-Ni alloy 1J22 with μ=6000-8000) can strongly guide magnetic flux lines from the magnetic flux leakage area of the magnet assembly to the target surface, increasing the effective magnetic field strength on the target surface by 40%-60% (compared to the working condition without magnetic ring). Experiments show that when the magnetic permeability increases from 3000 to 5000, the acceleration of the arc spot driven by the Lorentz force increases from 2×10 4 m / s 2 Increased to 4×10 4 m / s 2 .

[0123] Reduced magnetic resistance: High permeability materials significantly reduce the magnetic resistance in the magnetic circuit, increasing the magnetic energy product utilization of the magnet assembly from 50% in traditional designs to over 85%. If the magnetic permeability is insufficient (such as μ = 2000 for ordinary carbon steel), the magnetic flux lines will be largely dispersed to the vacuum chamber walls, causing the magnetic field strength on the target surface to decrease by more than 30%.

[0124] The selection of the matching tolerance between the inner diameter of the magnetic ring and the outer diameter of the magnet assembly needs to balance the assembly accuracy and thermal expansion tolerance:

[0125] Clearance Control: H7 / g6 is the base hole clearance fit. The hole diameter tolerance is H7 (+0.025 / 0mm), and the shaft diameter tolerance is g6 (-0.009 / -0.025mm). The actual clearance is 0.009-0.050mm. This clearance range ensures quick assembly of the magnetic ring and magnet assembly (no press-fit fixture required) while preventing magnetic flux leakage caused by excessive clearance (magnetic flux leakage rate <5%).

[0126] Thermal expansion adaptation: The thermal expansion coefficient of NdFeB magnets is 1.2×10 -6 / ℃, the iron-nickel alloy magnetic ring is 1.5×10 -6 / ℃. When the operating temperature rises from 20℃ to 180℃, the outer diameter of the magnet expands by about 0.03mm, and the inner diameter of the magnetic ring expands by about 0.04mm. The H7 / g6 gap can completely absorb thermal deformation and avoid magnetic circuit distortion caused by thermal stress.

[0127] The characteristics and applicable scenarios of the three types of magnetic materials are as follows:

[0128] Iron-nickel alloys (such as 1J22 and 1J85): have the highest magnetic permeability (μ = 6000-15000) and the lowest coercive force (Hc ≤ 1Oe), and are particularly suitable for high-precision magnetic field control scenarios (such as graphite target coating).

[0129] The disadvantages are high cost (about 10 times that of silicon steel) and low mechanical strength (tensile strength 500MPa), and it needs to be used with a reinforced bracket.

[0130] Silicon steel (such as 35W300): The most economical (the cost is 1 / 10 of that of iron-nickel alloy), high saturation magnetic induction (Bs = 2.0T), suitable for large-sized magnetic rings (diameter > 500mm) and medium and low magnetic field strength requirements (0.5-0.8T).

[0131] The magnetic permeability is low (μ=5000-7000) and the high-frequency loss is large, so the operating frequency needs to be limited to <100Hz (corresponding to the target rotation speed <6000rpm).

[0132] Nanocrystalline soft magnetic alloys (such as Fe-Si-B-Nb-Cu): have the best overall performance, with a magnetic permeability of μ = 8000-10000, a saturation magnetic induction of Bs = 1.25T, and excellent high-frequency characteristics (applicable frequency up to 10kHz), suitable for the dynamic magnetic field requirements of high-speed coating (10000rpm).

[0133] The preparation process is complex (requires rapid cooling and strip spinning + crystallization annealing), and the cost is between iron-nickel alloy and silicon steel, making it suitable for high-end coating equipment.

[0134] Furthermore, the gear module of the power transmission system is 2-4, the transmission ratio is 1:1 to 1:3, and the meshing clearance of the gear pair is controlled within the range of 0.05-0.15 mm by an eccentric sleeve adjustment mechanism.

[0135] Specifically, the power transmission system's gear module is limited to 2-4, with a transmission ratio range of 1:1 to 1:3. An eccentric sleeve adjustment mechanism controls the gear pair meshing clearance within a range of 0.05-0.15mm. This refined design prioritizes power transmission efficiency, vibration and noise suppression, and equipment longevity under high-speed operating conditions. By collaboratively optimizing gear geometry, kinematic characteristics, and the adjustment mechanism, this solution achieves precise control of target rotational speed and stable and reliable operation of the transmission system, providing the fundamental power support for the dynamic magnetic field coupling of the arc ion plating process.

[0136] Module is the core parameter in gear design, which directly affects the tooth root strength, load capacity and transmission stability. This device limits the module to 2-4, based on the following:

[0137] Lower module 2: Suitable for low torque, high speed scenarios (such as copper target coating, transmission ratio 1:1). Small module gears have more teeth (usually ≥20 teeth), high meshing contact frequency, and excellent transmission stability (vibration acceleration <0.5g), but the single tooth load capacity is low (≤200N / mm 2 ), must be used with a low-load motor.

[0138] Upper limit module 4: Adapt to high torque requirements (such as graphite target coating, transmission ratio 1:3). Large module gear tooth root thickness increases (tooth root stress ≤ 150N / mm 2), can withstand the peak output torque of the motor > 50N·m, but the reduction in the number of teeth (usually ≤15 teeth) may lead to an increase in meshing impact noise (which needs to be compensated by clearance adjustment).

[0139] Module-speed-life balance: Experiments show that the tooth contact fatigue life (ISO 6336 standard) of module 3 gears at a speed of 10,000 rpm can reach 5,000 hours, with the best overall performance (wear rate <0.01 mm / kh).

[0140] The transmission ratio setting needs to match the target material properties and magnetic field drive requirements:

[0141] 1:1 direct drive: used for low speed requirements (3000-5000rpm) such as copper targets. The motor directly drives the target, with a transmission efficiency of >98% and minimal energy loss (<2%). However, the motor must have high torque output capability (e.g., a brushless DC motor with a peak torque >30N·m).

[0142] 1:3 speed-increasing transmission: For high-speed requirements (9,000-10,000 rpm) such as graphite targets, the small gear drives the large gear to double the speed. At this time, the motor operates in the high-efficiency range (6,000-7,000 rpm), taking into account both energy consumption and life (bearing wear rate is reduced by 40%).

[0143] Modular gear set: By replacing gear pairs with different numbers of teeth (such as 20 teeth / 60 teeth → 1:3, 40 teeth / 40 teeth → 1:1), the transmission mode can be quickly switched to adapt to diverse coating process requirements.

[0144] The meshing clearance of the gear pair directly affects the transmission accuracy, noise and wear rate. The coolant flow rate is 5-15L / min;

[0145] External circulation channel, cooling transmission system bearings, coolant flow rate is 2-8L / min;

[0146] The inner and outer circulation channels are sealed and connected via a rotary joint.

[0147] Specifically, the water cooling system utilizes a dual-circulation independent cooling structure. Through the differentiated design of internal and external circulation channels and the dynamic sealing connection of the rotary joint, this system achieves efficient and zoned thermal management of the target evaporation surface and transmission system bearings. This solution, based on the thermal load characteristics and spatial constraints of the target and transmission components during the arc ion plating process, ensures continuous and stable operation of the device under extremely high temperature and high-speed rotation conditions through cooling path optimization, precise flow control, and seal reliability design.

[0148] The internal circulation channel is directly embedded in the target material, and the coolant flows through the spiral microchannel (diameter 3-5mm, pitch 10-15mm) on the back of the evaporation surface to maximize the contact area and heat exchange efficiency. The coolant flow rate is set to 5-15L / min, with the lower limit of 5L / min corresponding to medium and low heat load scenarios such as copper targets (arc power ≤ 30kW), and the upper limit of 15L / min is suitable for high heat flux density conditions such as graphite targets (instantaneous heat flux > 5MW / m 2 Experiments have shown that increasing the flow rate from 5L / min to 15L / min can reduce the target surface temperature from 1200°C to 800°C, reducing thermal stress by 60% (finite element simulation data). Deionized water (specific heat capacity 4.18kJ / kg·K, conductivity <1μS / cm) is used as the cooling medium, balancing high heat capacity with insulation properties to avoid parasitic discharges caused by conductive coolant.

[0149] The external circulation channel independently cools the transmission system bearings and gearbox. The coolant flows along the annular gap (width 2-3mm) on the outer wall of the drive shaft, with a flow rate set at 2-8L / min. During low-speed coating (3000-5000rpm), the bearing temperature can be controlled to ≤60°C by maintaining a flow rate of 2-4L / min. Under high-speed conditions (9000-10000rpm), the flow rate is increased to 6-8L / min, and combined with the jet lubrication structure (oil-water mixture ratio 1:100), the temperature rise of the friction pair is reduced to <30°C. The cooling medium is ethylene glycol aqueous solution (40% by volume), with a freezing point of -30°C and a boiling point of 106°C, which ensures phase stability over a wide temperature range and suppresses corrosion of metal parts (corrosion inhibition rate >95%).

[0150] This technical solution overcomes the thermal management difficulties of rotating components and stationary systems in high-energy beam equipment through the deep integration of zoned and graded cooling and dynamic sealing technology, providing a reliable thermal protection system for the industrial continuous production of arc ion plating process.

[0151] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present disclosure, and should all be included in the scope of protection of the present disclosure.

Claims

1. An arc ion plating device with target rotation and magnetic field coupling, characterized in that: include: A target (1) is arranged at the center of the device; A shielding cover (2) is coaxially sleeved on the outside of the target material and completely covers the target material; An annular magnet assembly (3) is coaxially arranged outside the shielding cover and comprises two semicircular arc-shaped permanent magnets with opposite magnetic poles, wherein the arc range of the semicircular arc-shaped permanent magnets is 30° to 160°; A magnetic conductive ring (4) is coaxially wrapped around the outer side of the magnet assembly to form a closed magnetic circuit; A power transmission system comprises a first gear (6a) and a second gear (6b) meshing with each other, wherein the first gear is rigidly connected to the target material via a transmission shaft, and the second gear is connected to an output shaft of a driving motor (7); A magnetic fluid sealing assembly (5) is disposed below the target material and is sealed and connected to the transmission shaft; A water cooling system (8) is integrated into the transmission shaft and forms a heat conduction path with the target material; Among them, the target material, shielding cover, annular magnet assembly and magnetic conductive ring constitute the working assembly inside the vacuum chamber, the power transmission system, drive motor and water cooling system constitute the driving assembly outside the vacuum chamber, and the magnetic fluid sealing assembly realizes the sealing isolation between the inside and outside of the vacuum chamber.

2. The arc ion plating device according to claim 1, characterized in that The curvature of the semicircular permanent magnet is positively correlated with the target rotation speed, specifically satisfying: When the target rotation speed is 3000-5000rpm, the magnet arc is 30°-60°; When the target rotation speed is 6000-8000rpm, the magnet arc is 60°-90°; When the target rotation speed is 9000-10000rpm, the magnet arc is 90°-160°.

3. The arc ion plating device according to claim 1, characterized in that The target material (1) is made of any conductive material selected from graphite, titanium or copper, and has a surface roughness Ra of ≤0.8 μm and a purity of ≥99.95%.

4. The arc ion plating device according to claim 1, wherein The shielding cover (2) is made of non-magnetic material, and the distance between its inner surface and the outer surface of the target material is 5-15 mm. The non-magnetic material includes titanium alloy or stainless steel with surface passivation treatment, and the passivation layer thickness is 2-5 μm.

5. The arc ion plating device according to claim 1, wherein The annular magnet assembly (3) is made of neodymium iron boron permanent magnet material, the surface magnetic induction intensity of which is 0.5-1.2T, the Curie temperature is ≥350°C, and the contact surface of the two semicircular arc-shaped permanent magnets is provided with a magnetic conductive gap of 0.1-0.5mm.

6. The arc ion plating device according to claim 1, characterized in that The magnetic permeability of the magnetic ring (4) is ≥5000, the matching tolerance between its inner diameter and the outer diameter of the magnet assembly is H7 / g6, and the material is selected from any one of iron-nickel alloy, silicon steel or nanocrystalline soft magnetic alloy.

7. The arc ion plating device according to claim 1, characterized in that The gear module of the power transmission system is 2-4, the transmission ratio is 1:1 to 1:3, and the meshing clearance of the gear pair is controlled within the range of 0.05-0.15 mm by an eccentric sleeve adjustment mechanism.

8. The arc ion plating device according to claim 1, wherein The magnetic fluid sealing component (5) comprises a multi-stage magnetic pole structure, the sealing pressure of each stage is ≥0.15MPa, the overall pressure difference is ≥1.5MPa, and the applicable temperature range is -50°C to 200°C.

9. The arc ion plating device according to claim 1, characterized in that The water cooling system (8) adopts a double-circulation cooling structure, comprising: Internal circulation channel, directly cools the evaporation surface of the target material, with a coolant flow rate of 5-15L / min; External circulation channel, cooling transmission system bearings, coolant flow rate is 2-8L / min; The inner and outer circulation channels are sealed and connected via a rotary joint.

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