Low-impedance black PVD film layer and preparation method thereof

Abstract

The present application relates to a kind of low impedance black PVD film layer and its preparation method, belong to physical vapor deposition technical field;Using magnetron sputtering coating machine, process gas pipe is arranged in the central vacuum chamber;Preparation steps include: two pairs of chromium target, a pair of tungsten carbide target and a pair of graphite target are installed in vacuum chamber;After substrate pretreatment, argon ion bombardment cleaning, deposition pure chromium adhesion layer is sequentially carried out, gradient adjusting target current and bias mode is used to co-deposit the transition layer of chromium, tungsten carbide and graphite;Finally, under low bias, low duty ratio, acetylene gas is reacted and deposited color layer, obtain black PVD film layer, the present application is realized by central gas inlet gas uniform distribution, and combined with component gradient transition layer and low bias reaction deposition process, effectively inhibit the generation of high resistance amorphous carbon, make film layer impedance stable below 2Ω, simultaneously have the advantages such as strong bonding force, color even, corrosion resistance is good.

Description

Technical Field

[0001] This invention relates to the field of physical vapor deposition technology, and in particular to a low-impedance black PVD film and its preparation method. Background Technology

[0002] In recent years, smart wearables have been increasingly widely used in social life. The health monitoring and interaction functions of smart wearable devices that utilize bioelectric currents, such as ECG (electrocardiogram monitoring), EMG (electromyography monitoring), and EEG (electroencephalogram monitoring), are based on capturing the weak electrical signals generated during human life activities. These signals are then converted into interpretable health data or interactive commands through signal processing and algorithm analysis. Some components of smart wearable devices need to have a black appearance, so a low-impedance black PVD film layer is required to transmit these weak electrical signals.

[0003] In existing technologies, the preparation of black PVD films often involves using metal targets (such as chromium and titanium) doped with a large amount of carbon, or directly using ceramic targets. However, this approach has the following drawbacks: First, films prepared by doping metal targets with a large amount of carbon have a low proportion of metal components and a high proportion of non-conductive carbides or elemental carbon. The film impedance is usually greater than 10Ω, which is difficult to meet the requirements of low-impedance applications. Second, the preparation of some low-impedance films requires complex multi-element target combinations or subsequent modification processes, resulting in high preparation costs and poor process stability.

[0004] The black films prepared using graphite targets in existing technologies often suffer from problems such as large impedance fluctuations (>5Ω), easy film detachment, and obvious color differences, which cannot meet the needs of industrial mass production.

[0005] Therefore, there is a need for a simple and stable process that can achieve an impedance of <2Ω for the preparation of black PVD films. Summary of the Invention

[0006] The purpose of this invention is to provide a low-impedance black PVD film and its preparation method, achieving a low impedance characteristic of <2Ω while ensuring uniformity of film appearance and stability of performance.

[0007] The technical solution for achieving the objective of this invention is as follows: the preparation apparatus of this invention employs a coating machine; the preparation apparatus employs a coating machine, wherein the coating machine is an arc ion coating machine, and the coating machine has a vacuum chamber, multiple arc target power supplies, a bias power supply, a heater, a vacuum system, and an air intake system; characterized in that: the vacuum chamber of the coating machine is provided with a process gas pipe, which is located in the center of the vacuum chamber, including the following steps: S1. Prepare a pair of graphite targets, a pair of tungsten carbide targets, and two pairs of chromium targets. Place the pair of graphite targets, the pair of tungsten carbide targets, and the two pairs of chromium targets inside the vacuum chamber of the coating machine. S2. Next, prepare the untreated substrate required for coating and pretreat the untreated substrate. S3. Multiple arc target power supplies correspond to a pair of graphite targets, a pair of tungsten carbide targets, and two pairs of chromium targets, which are divided into graphite target power supplies, tungsten carbide target power supplies, first chromium target power supplies, and second chromium target power supplies. The pretreated substrate is placed inside the vacuum chamber of the coating machine, the heater of the coating machine is turned on to heat the vacuum chamber, and the vacuum system of the coating machine is used to perform vacuuming. S4. The air intake system introduces argon gas into the vacuum chamber through the process gas pipe, turns on the bias power supply, adjusts the power supply current, bias voltage and bias duty cycle, and adjusts the flow rate of the argon gas. The bias power supply bombards and cleans the substrate surface. S5. Turn off the bias power supply, adjust the argon flow rate and the vacuum pressure inside the vacuum chamber, turn on the first chromium target power supply, adjust the power current and bias voltage of the first chromium target power supply, and bombard the chromium target to obtain chromium particles. The chromium particles are deposited on the surface of the substrate to obtain an adhesion layer. S6. Turn on the second chromium target power supply, turn on the tungsten carbide target power supply, turn on the graphite target power supply, and then gradually adjust the power current, bias voltage, and deposition time of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply. The first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply bombard the chromium target, the tungsten carbide target, and the graphite target respectively to obtain chromium particles, tungsten carbide particles, and graphite particles. The chromium particles, tungsten carbide particles, and graphite particles are deposited in the adhesion layer to obtain the transition layer. S7. Adjust the power supply current, bias voltage, and bias voltage duty cycle of the first chromium target power supply, tungsten carbide target power supply, and graphite target power supply again. Then adjust the argon gas flow rate introduced into the vacuum chamber through the process gas pipe and adjust the vacuum pressure inside the vacuum chamber. After that, the gas inlet system introduces acetylene gas into the vacuum chamber through the process gas pipe and adjusts the flow rate of the introduced acetylene gas. The acetylene gas reacts with chromium particles, tungsten carbide particles, and graphite particles to deposit a color layer. S8. After the coating is completed, the vacuum chamber is kept in a vacuum state and allowed to cool naturally to obtain a black PVD film.

[0008] As a preferred embodiment of the present invention, the purity of the graphite target, tungsten carbide target and chromium target is ≥99.99%, and the graphite target, tungsten carbide target and chromium target are all circular tube rotating targets.

[0009] As a preferred embodiment of the present invention, in S3, the vacuum level inside the vacuum chamber reaches... The furnace temperature inside the vacuum chamber reaches 180℃.

[0010] As a preferred embodiment of the present invention, in S4, the power supply current of all arc target power supplies is 75A, the bias voltage is -300V, the bias duty cycle is 50%, the argon flow rate is 60sccm, and the bombardment time is 240s.

[0011] In a preferred embodiment of the present invention, in S5, the vacuum pressure inside the vacuum chamber is 1.0 to 1.2 Pa, the power supply current of the first chromium target power supply is 20 A, the bias voltage of the first chromium target power supply is set to -140 V, and the deposition time is 1500 s.

[0012] As a preferred embodiment of the present invention, S6 includes the following sub-steps: S6.1 The power supply current of the second chromium target power supply is 20A, the power supply current of the tungsten carbide target power supply is 20A, the power supply current of the graphite target power supply is 6A, and the bias voltage of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply is set to -130V, and the deposition time is 1800s. S6.2 Set the power supply current of the first chromium target power supply, the second chromium target power supply and the tungsten carbide target power supply to 18A, set the power supply current of the graphite target power supply to 10A, set the bias voltage of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply and the graphite target power supply to -125V, and set the deposition time to 3000s. S6.3 Set the power supply current of the first chromium target power supply, the second chromium target power supply and the tungsten carbide target power supply to 17A, set the power supply current of the graphite target power supply to 15A, set the bias voltage of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply and the graphite target power supply to -120V, and set the deposition time to 2400s. S6.4 Turn off the second chromium target power supply, set the power supply current of the first chromium target power supply and the tungsten carbide target power supply to 16A, set the power supply current of the graphite target power supply to 20A, set the bias voltage of the first chromium target power supply, the tungsten carbide target power supply and the graphite target power supply to -110V, and set the deposition time to 2400s.

[0013] In a preferred embodiment of the present invention, in S7, the power supply current of the first chromium target power supply is set to 5-9A, the power supply current of the tungsten carbide target power supply is set to 5-9A, the power supply current of the graphite target power supply is set to 20-25A, the bias voltage of the first chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply is set to -20 to -40V, the bias voltage duty cycle is set to 20% to 40%, the argon flow rate is changed to 250 sccm, the vacuum pressure inside the vacuum chamber is 0.8 to 1.0 Pa, the flow rate of acetylene gas introduced into the vacuum chamber through the process gas pipe is increased from 5 sccm to 55-65 sccm and maintained at 55-65 sccm, and the deposition time is 2400 s.

[0014] As a preferred embodiment of the present invention, in S8, the vacuum chamber is kept in a vacuum state and naturally cooled to 80°C.

[0015] In a preferred embodiment of the present invention, in S2, the substrate is a metal substrate or a ceramic substrate, wherein the metal substrate includes stainless steel or titanium alloy, and the ceramic substrate includes alumina; the pretreatment includes ultrasonic dewaxing, pure water rinsing, degreasing, pure water rinsing and vacuum drying performed sequentially.

[0016] A low-impedance black PVD film is prepared by the above-mentioned preparation method. The prepared black PVD film has a stable impedance of <2Ω and a thickness of 1.5~2.5μm.

[0017] The present invention has positive effects: (1) By setting the process gas pipe in the center of the vacuum chamber, the reaction gas (argon, acetylene) diffuses evenly from the center to the surrounding area, which solves the problem of uneven gas distribution caused by traditional side wall gas inlet, and significantly improves the uniformity of film thickness, color and resistivity. The present invention adopts a multi-layer gradient structure of "adhesion layer-transition layer-color layer", first depositing a pure chromium adhesion layer to improve the bonding force, then gradually introducing tungsten carbide and graphite to form a compositional gradient transition layer, which relieves the internal stress of the film layer. Finally, under low bias voltage and low bias voltage duty cycle, acetylene is introduced to react and deposit the color layer, which effectively controls the form and content of carbon in the film layer, avoids the excessive generation of high-resistivity amorphous carbon, and thus achieves a low-resistivity black film layer with stable impedance <2Ω.

[0018] (2) The present invention uses high-purity target material with a purity of ≥99.99%, which reduces the interference of impurity elements on the conductivity and color of the film; the circular tube rotating target has a high utilization rate in arc ion plating, and the target surface is uniformly ablated, which ensures the stability of plasma emission during long-term deposition and is conducive to the consistency of film composition and impedance.

[0019] (3) The present invention evacuates the vacuum chamber to The high vacuum and heating to 180°C effectively eliminated residual atmospheres such as water vapor and oxygen, reduced the risk of membrane contamination and oxidation, and improved membrane density and purity, laying the foundation for subsequent low impedance performance.

[0020] (4) In the bombardment cleaning step, the present invention uses argon ion bombardment with high current, high bias voltage and medium duty cycle, which can effectively remove the oxide layer and adsorbed impurities on the substrate surface, while activating the substrate surface, forming micro-roughness, and significantly enhancing the mechanical locking and chemical bonding force between the subsequent film layer and the substrate.

[0021] (5) In the deposition of the adhesion layer, the vacuum pressure is controlled at a relatively high pressure of 1.0 to 1.2 Pa, and a relatively low target current of 20 A and a moderate bias voltage of -140 V are used to make the deposited pure chromium layer dense and with low internal stress, and with good matching with the substrate, providing an excellent conductive substrate and bonding transition layer for the entire film structure.

[0022] (6) The present invention gradually reduces the target current of chromium and tungsten carbide through four sub-steps S6.1 to S6.4, while gradually increasing the target current of graphite and correspondingly reducing the bias voltage, thereby realizing the gradual change of composition gradient from chromium-rich layer to carbon-rich layer; effectively eliminating the interface stress concentration caused by the difference in thermal expansion coefficient and hardness of chromium, tungsten carbide and graphite, preventing the film layer from cracking or peeling off, while ensuring that the entire transition layer still has a low resistivity.

[0023] (7) In the color layer deposition stage, the present invention significantly reduces the target current of chromium and tungsten carbide and increases the target current of graphite. At the same time, acetylene gas is introduced under extremely low bias voltage and low duty cycle. This promotes the reaction of acetylene with metal particles to generate a metal carbide with good conductivity (such as CrC, WC) rather than an insulating diamond-like film. Meanwhile, the excess graphite particles exist in the form of microcrystalline or amorphous carbon but do not form a continuous high-resistivity layer. Finally, the film layer is pure black and has extremely low resistance (<2Ω). The acetylene flow rate is slowly increased from 5 sccm to 55-65 sccm to avoid abrupt carbon deposition and ensure uniform transition of film layer composition.

[0024] (8) After the coating is completed, the film is naturally cooled to below 80°C in a vacuum before being taken out, which avoids the deterioration of the film surface properties caused by high temperature oxidation, and also prevents thermal stress cracks caused by rapid cooling, thus ensuring the integrity and low impedance stability of the film.

[0025] (9) This invention is applicable to metal substrates such as stainless steel and titanium alloys as well as ceramic substrates such as alumina. Through standard pretreatment processes such as ultrasonic dewaxing, degreasing, pure water rinsing and vacuum drying, the surface cleanliness of the substrate is ensured, which provides the necessary conditions for subsequent high-quality deposition and broadens the application range of this low-impedance black PVD film.

[0026] (10) The PVD film prepared by the above-mentioned optimized process has an impedance stability of less than 2Ω. It has been verified by salt spray test, tape peel test and other tests that it has excellent adhesion and good corrosion resistance. It can meet the requirements of low resistance black coating for grounding, antistatic, electromagnetic shielding and high-end decoration of electronic equipment. Attached Figure Description

[0027] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1This is a flowchart of the preparation method of the present invention; Figure 2 This is a schematic diagram of the structure of the black PVD film prepared according to the present invention; Figure 3 This is a schematic diagram showing the distribution of the target material and process gas pipes of the present invention; Figure 4 A schematic diagram of impedance testing of the black PVD film prepared for the invention.

[0028] In the figure, graphite target: 1, tungsten carbide target: 2, chromium target: 3, process gas pipe: 4, substrate: a, adhesion layer: a1, transition layer: a2, color layer: a3, film contact point: P, substrate contact point: Q. Detailed Implementation

[0029] See Figures 1 to 4 The preparation apparatus of the present invention employs a coating machine; the coating machine is an arc ion coating machine, which has a vacuum chamber, multiple arc target power supplies, a bias power supply, a heater, a vacuum system, and an air intake system; the vacuum chamber of the coating machine is equipped with a process gas pipe 4, which is located in the center of the vacuum chamber, and the pipe wall of the process gas pipe 4 has multiple air outlets to ensure uniform distribution of the reaction gas; the coating machine also includes a programmable logic controller (PLC) for controlling the output parameters of each power supply and the gas flow rate.

[0030] Preferably, the coating machine in this invention is a TC-1850 coating machine from Shenzhen Tiancheng Vacuum Technology Co., Ltd. The inner wall of the TC-1850 coating machine is equipped with a revolving mechanism for loading the substrate a; the preparation method includes the following steps: S1. Prepare a pair of graphite targets, a pair of tungsten carbide targets 22, and two pairs of chromium targets 3. Place the pair of graphite targets (C), the pair of tungsten carbide targets 22 (WC), and the two pairs of chromium targets 3 (Cr) on the orbital mechanism inside the vacuum chamber of the coating machine. The two pairs of chromium targets 3 are located on one side of the process gas pipe 4, and the pair of graphite targets and the pair of tungsten carbide targets 22 are located on the other side of the process gas pipe 4. The pair of tungsten carbide targets 22 are set close to the process gas pipe 4, and the pair of graphite targets are set away from the process gas pipe 4. The term "pair" refers to two targets. Each pair of targets is installed opposite or adjacent to each other in the vacuum chamber to ensure coating uniformity. S2. Next, prepare the untreated substrate a required for coating and perform pretreatment on the untreated substrate a; the substrate a is a metal substrate a or a ceramic substrate a, the metal substrate a includes stainless steel or titanium alloy, and the ceramic substrate a includes alumina; the pretreatment includes ultrasonic dewaxing, pure water rinsing, degreasing, pure water rinsing and vacuum drying in sequence. Preferably, the substrate a is made of stainless steel, and SUS316 stainless steel sample is specially selected as substrate a; S3. Multiple arc target power supplies correspond to a pair of graphite targets, a pair of tungsten carbide targets 22, and two pairs of chromium targets 3. The areas are divided into graphite target power supplies, tungsten carbide target power supplies, first chromium target power supplies, and second chromium target power supplies. The pretreated substrate a is placed inside the vacuum chamber of the coating machine. The heater of the coating machine is turned on to heat the vacuum chamber, and the vacuum pumping system of the coating machine is used to pump the vacuum. The "multiple arc target power supplies" in this step are not a separate type of power supply from the arc target power supply, but refer to the bias power supply. The substrate a is connected to the bias power supply, and each target is connected to its own arc target power supply. Specifically, the internal vacuum level of the vacuum chamber reaches The internal furnace temperature is then maintained at 180°C. S4. Argon gas is introduced into the vacuum chamber through the process gas pipe 4. The bias power supply connected to the substrate a is turned on, and the parameters of the bias power supply are adjusted as follows: bias voltage is -300V, bias duty cycle is 50%, power supply current is set to 75A, and the argon gas flow rate is adjusted to 60sccm. Under the action of bias voltage, argon ions generated by argon gas ionization bombard the surface of substrate a for physical sputtering cleaning. The bombardment time is 240s. This step uses high-energy ion bombardment to remove residual microscopic impurities on the surface of substrate a and activate the surface, providing a high-adhesion interface for subsequent coatings. S5. Turn off the bias power supply, adjust the argon flow rate to 200 sccm, and stabilize the vacuum pressure inside the vacuum chamber at 1.0~1.2 Pa; turn on the first chromium target power supply, adjust the power supply current of the first chromium target power supply to 20A, and the bias voltage to -140V. The first chromium target power supply bombards the chromium target 3 to obtain chromium particles. The chromium particles are deposited on the surface of the substrate a for 1500s to obtain the adhesion layer a1. S6. Turn on the second chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply. Then, gradually adjust the power current, bias voltage, and deposition time of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply. The first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply bombard the chromium target 3, the tungsten carbide target 22, and the graphite target, respectively, to obtain chromium particles, tungsten carbide particles, and graphite particles. The chromium particles, tungsten carbide particles, and graphite particles are deposited in the adhesion layer a1 to obtain the transition layer a2. In this step, all targets work simultaneously, and the proportions of chromium, tungsten carbide, and graphite in the deposited transition layer a2 change in a gradient. Specifically, this includes the following sub-steps, which are performed continuously without interruption of the vacuum: S6.1 The power supply current of the second chromium target power supply is 20A, the power supply current of the tungsten carbide target power supply is 20A, the power supply current of the graphite target power supply is 6A, and the bias voltage of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply is set to -130V, and the deposition time is 1800s. S6.2 Set the power supply current of the first chromium target power supply, the second chromium target power supply and the tungsten carbide target power supply to 18A, set the power supply current of the graphite target power supply to 10A, set the bias voltage of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply and the graphite target power supply to -125V, and set the deposition time to 3000s. S6.3 Set the power supply current of the first chromium target power supply, the second chromium target power supply and the tungsten carbide target power supply to 17A, set the power supply current of the graphite target power supply to 15A, set the bias voltage of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply and the graphite target power supply to -120V, and set the deposition time to 2400s. S6.4 Turn off the second chromium target power supply, set the power supply current of the first chromium target power supply and the tungsten carbide target power supply to 16A, set the power supply current of the graphite target power supply to 20A, set the bias voltage of the first chromium target power supply, the tungsten carbide target power supply and the graphite target power supply to -110V, and set the deposition time to 2400s.

[0031] Through the gradient deposition from S6.1 to S6.4, the chromium content in the transition layer a2 gradually decreases, while the tungsten carbide and graphite content gradually increases, forming a gradual transition from metallic to non-metallic properties. This effectively reduces internal stress, prevents film peeling, and initially establishes a conductive network.

[0032] S7. Adjust the power supply current, bias voltage, and bias voltage duty cycle of the first chromium target power supply, tungsten carbide target power supply, and graphite target power supply again. Then adjust the flow rate of argon gas introduced into the vacuum chamber through process gas pipe 4 and adjust the vacuum pressure inside the vacuum chamber. After that, the gas inlet system introduces acetylene gas into the vacuum chamber through process gas pipe 4 and adjusts the flow rate of the introduced acetylene gas. The acetylene gas reacts with chromium particles, tungsten carbide particles, and graphite particles to deposit the color layer a3. The specific parameters are as follows: the power supply current of the first chromium target is set to 5-9A, the power supply current of the tungsten carbide target is set to 5-9A, the power supply current of the graphite target is set to 20-25A, the bias voltage of the first chromium target, the tungsten carbide target, and the graphite target is set to -20 to -40V, the bias voltage duty cycle is set to 20% to 40%, the argon flow rate is changed to 250 sccm, the vacuum pressure inside the vacuum chamber is 0.8 to 1.0 Pa, the flow rate of acetylene gas introduced into the vacuum chamber through process gas pipe 4 is linearly increased from 5 sccm to 55-65 sccm and maintained at 55-65 sccm, and the deposition time is 2400s.

[0033] The aforementioned "bias duty cycle" refers to the proportion of time the bias voltage is applied; it does not refer to the magnitude of the voltage, but rather to how long the voltage "works" and "rests".

[0034] It is worth noting that the gradual introduction of acetylene is used to avoid target poisoning or film powdering caused by a sudden increase in reactive gases. The final color layer a3 is black (L value ≤ 30), with a thickness of 1.5~2.5μm, and contains chromium carbides. Tungsten carbides (WC) and a small amount of sp² / sp³ hybrid carbon together constitute a low-resistance channel.

[0035] S8. After the coating is completed, maintain the vacuum state of the vacuum chamber and allow it to cool naturally to 80°C to obtain a black PVD film.

[0036] As a preferred embodiment of the present invention, the purity of the graphite target, the tungsten carbide target 22 and the chromium target 3 are all ≥99.99%, and the graphite target, the tungsten carbide target 22 and the chromium target 3 are all circular tube rotating targets.

[0037] The distributions of the aforementioned chromium target 3, tungsten carbide target 22, and graphite target are as follows: Figure 3 As shown.

[0038] The black PVD film prepared by the above method has a stable impedance of <2Ω, and the thickness of the prepared black PVD film is controlled to be 1.5~2.5μm.

[0039] The correspondence between the above terms is as follows: First chromium target power supply: connects to a pair of chromium targets 3 and bombards the pair of chromium targets 3.

[0040] Second chromium target power supply: Connects to another pair of chromium targets 3 and bombards the other pair of chromium targets 3.

[0041] Tungsten carbide target power supply: connects to a pair of tungsten carbide targets 22 and bombards the pair of tungsten carbide targets 22.

[0042] Graphite target power supply: connects to a pair of graphite targets and bombards the pair of graphite targets.

[0043] The following are the performance testing methods for the obtained black PVD film: Impedance testing: The impedance between the film surface and point a on the substrate was measured using an impedance meter. See [reference needed]. Figure 4 P is the film contact point, and Q is the substrate a contact point. The measurement is performed at points p and q using the 4-line method. Point P is on the surface of the film, and point Q is on the electroplated gold surface.

[0044] The following is a table of impedance test data for the prepared PVD films:

[0045] As shown in the table above, the resistance of all samples was much lower than 2Ω under the three test conditions, and the average resistance was less than 0.5Ω, which proves that the black PVD film has excellent low impedance characteristics and is suitable for occasions with strict requirements for conductivity.

[0046] Appearance test: The film surface is uniform and matte black when observed with the naked eye, with no obvious color difference, pinholes or film peeling.

[0047] Adhesion test: According to the GB / T 9286-1998 test standard, the tape was tested after being cut with a cross-cut tester. The film layer did not peel off, and the adhesion reached level 5B.

[0048] Neutral salt spray test: 48 hours test according to GB / T 10125-2021 standard, no rust, no discoloration, and no film peeling.

[0049] It should be noted that the above-mentioned technical features do not necessarily have to exist simultaneously; those skilled in the art can combine any of the above-mentioned technical features in any way according to actual needs, and as long as such combination is logically feasible, it falls within the scope of this application.

[0050] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a low-impedance black PVD film, wherein the preparation apparatus employs a coating machine, specifically an arc ion plating machine, which includes a vacuum chamber, multiple arc target power supplies, a bias power supply, a heater, a vacuum system, and an air intake system; characterized in that: The coating machine has a process gas pipe inside its vacuum chamber, which is located in the center of the vacuum chamber. The process gas pipe includes the following steps: S1. Prepare a pair of graphite targets, a pair of tungsten carbide targets, and two pairs of chromium targets. Place the pair of graphite targets, the pair of tungsten carbide targets, and the two pairs of chromium targets inside the vacuum chamber of the coating machine. S2. Next, prepare the untreated substrate required for coating and pretreat the untreated substrate. S3. Multiple arc target power supplies correspond to a pair of graphite targets, a pair of tungsten carbide targets, and two pairs of chromium targets, which are divided into graphite target power supplies, tungsten carbide target power supplies, first chromium target power supplies, and second chromium target power supplies. The pretreated substrate is placed inside the vacuum chamber of the coating machine, the heater of the coating machine is turned on to heat the vacuum chamber, and the vacuum pumping system of the coating machine is used to pump the vacuum. S4. The air intake system introduces argon gas into the vacuum chamber through the process gas pipe, turns on the bias power supply, adjusts the power supply current, bias voltage and bias duty cycle, and adjusts the flow rate of the argon gas. The bias power supply bombards and cleans the substrate surface. S5. Turn off the bias power supply, adjust the argon flow rate and the vacuum pressure inside the vacuum chamber, turn on the first chromium target power supply, adjust the power current and bias voltage of the first chromium target power supply, and bombard the chromium target to obtain chromium particles. The chromium particles are deposited on the surface of the substrate to obtain an adhesion layer. S6. Turn on the second chromium target power supply, turn on the tungsten carbide target power supply, turn on the graphite target power supply, and then gradually adjust the power current, bias voltage, and deposition time of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply. The first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply bombard the chromium target, the tungsten carbide target, and the graphite target respectively to obtain chromium particles, tungsten carbide particles, and graphite particles. The chromium particles, tungsten carbide particles, and graphite particles are deposited in the adhesion layer to obtain the transition layer. S7. Adjust the power supply current, bias voltage, and bias duty cycle of the first chromium target power supply, tungsten carbide target power supply, and graphite target power supply again. Then adjust the argon gas flow rate introduced into the vacuum chamber through the process gas pipe and adjust the vacuum pressure inside the vacuum chamber. After that, the gas inlet system introduces acetylene gas into the vacuum chamber through the process gas pipe and adjusts the flow rate of the introduced acetylene gas. The acetylene gas reacts with chromium particles, tungsten carbide particles, and graphite particles to deposit a color layer. S8. After the coating is completed, the vacuum chamber is kept in a vacuum state and allowed to cool naturally to obtain a black PVD film.

2. The method for preparing a low-resistivity black PVD film according to claim 1, characterized in that: The purity of the graphite target, tungsten carbide target, and chromium target is ≥99.99%, and all three targets are circular tube rotating targets.

3. The method for preparing a low-impedance black PVD film according to claim 1, characterized in that: In S3, the vacuum level inside the vacuum chamber reaches... The furnace temperature inside the vacuum chamber reaches 180℃.

4. The method for preparing a low-resistivity black PVD film according to claim 1, characterized in that: In S4, all arc target power supplies have a power supply current of 75A, a bias voltage of -300V, a bias duty cycle of 50%, an argon flow rate of 60sccm, and a bombardment time of 240s.

5. The method for preparing a low-impedance black PVD film according to claim 1, characterized in that: In S5, the vacuum pressure inside the vacuum chamber is 1.0 to 1.2 Pa, the power supply current of the first chromium target is 20 A, the bias voltage of the first chromium target is set to -140 V, and the deposition time is 1500 s.

6. The method for preparing a low-impedance black PVD film according to claim 1, characterized in that: S6 includes the following sub-steps: S6.1 The power supply current of the second chromium target power supply is 20A, the power supply current of the tungsten carbide target power supply is 20A, the power supply current of the graphite target power supply is 6A, and the bias voltage of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply is set to -130V, and the deposition time is 1800s. S6.2 Set the power supply current of the first chromium target power supply, the second chromium target power supply and the tungsten carbide target power supply to 18A, set the power supply current of the graphite target power supply to 10A, set the bias voltage of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply and the graphite target power supply to -125V, and set the deposition time to 3000s. S6.3 Set the power supply current of the first chromium target power supply, the second chromium target power supply and the tungsten carbide target power supply to 17A, set the power supply current of the graphite target power supply to 15A, set the bias voltage of the first chromium target power supply, the second chromium target power supply, the tungsten carbide target power supply and the graphite target power supply to -120V, and set the deposition time to 2400s. S6.4 Turn off the second chromium target power supply, set the power supply current of the first chromium target power supply and the tungsten carbide target power supply to 16A, set the power supply current of the graphite target power supply to 20A, set the bias voltage of the first chromium target power supply, the tungsten carbide target power supply and the graphite target power supply to -110V, and set the deposition time to 2400s.

7. The method for preparing a low-resistivity black PVD film according to claim 1, characterized in that: In S7, the power supply current of the first chromium target power supply is set to 5-9A, the power supply current of the tungsten carbide target power supply is set to 5-9A, and the power supply current of the graphite target power supply is set to 20-25A. The bias voltage of the first chromium target power supply, the tungsten carbide target power supply, and the graphite target power supply is set to -20 to -40V, and the bias duty cycle is set to 20% to 40%. The argon flow rate is changed to 250 sccm, the vacuum pressure inside the vacuum chamber is 0.8 to 1.0 Pa, the flow rate of acetylene gas introduced into the vacuum chamber through the process gas pipe is increased from 5 sccm to 55-65 sccm and maintained at 55-65 sccm, and the deposition time is 2400 s.

8. The method for preparing a low-impedance black PVD film according to claim 1, characterized in that: In S8, the vacuum chamber is kept in a vacuum state and allowed to cool naturally to 80°C.

9. The method for preparing a low-resistivity black PVD film according to claim 1, characterized in that: In S2, the substrate is a metal substrate or a ceramic substrate. The metal substrate includes stainless steel or titanium alloy, and the ceramic substrate includes alumina. The pretreatment includes ultrasonic dewaxing, pure water rinsing, degreasing, pure water rinsing and vacuum drying performed sequentially.

10. A low-resistivity black PVD film, characterized in that, The black PVD film prepared by any one of claims 1 to 9 has a stable impedance of <2Ω and a thickness of 1.5~2.5μm.

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