A platinum composite wire and its plating method

Abstract

This invention relates to the field of metal processing technology, and discloses a platinum composite wire and its plating method, aiming to solve the problems of insufficient bonding strength, coating defects, and poor stability caused by material lattice mismatch and stress concentration in existing plating technologies. The composite wire comprises, from the inside out, a conductor substrate, a first transition layer, a nickel-platinum alloy second transition layer, and a platinum functional layer. The plating method employs multi-stage pulsed magnetron sputtering technology to prepare dense, fine-grained layers, combined with online monitoring and feedback control. The gradient stress buffer design significantly reduces stress concentration at each interface, making the coating less prone to peeling and detachment under thermal cycling and external mechanical stress, increasing the bonding strength from less than 100 MPa in traditional methods to over 300 MPa. Through the above solution, this invention significantly improves the bonding strength, density, microstructure uniformity, and long-term operational reliability of the platinum coating under high-frequency and high-power environments.

Description

Technical Field

[0001] This invention belongs to the field of metal material processing technology, and specifically relates to a platinum composite wire and its plating method. Background Technology

[0002] To form a dense platinum coating on the surface of conductive substrates, those skilled in the art primarily employ electrochemical plating and physical vapor deposition, particularly magnetron sputtering. Electroplating, as a long-established and cost-effective method, can relatively easily produce thick platinum layers. However, inherent limitations of electroplating, such as the generation of significant internal stress within the coating, the potential for hydrogen co-deposition during deposition leading to decreased purity and structural defects, and the challenge of controlling coating uniformity on substrates with complex geometries, limit its application in high-precision, high-performance electronic devices. This is especially true in scenarios demanding extreme reliability and long-term stability, where the bonding strength and microstructure between the coating and the substrate often fail to meet increasing requirements. In contrast, physical vapor deposition, represented by magnetron sputtering, is gradually becoming the mainstream choice for preparing high-quality platinum coatings due to its ability to achieve high-purity, dense, and uniform thin film deposition and its superior control over the coating's microstructure. By precisely controlling the sputtering parameters, physical vapor deposition technology can theoretically improve the adhesion between the coating and the substrate, reduce the incorporation of impurities, and thus enhance the overall performance of the coating.

[0003] However, as modern electronic systems continue to evolve towards higher operating frequencies, higher integration levels, and more demanding operating environments, especially in microwave / millimeter-wave devices at 10 GHz and above, and in applications such as satellite communication antennas with extremely high long-term reliability requirements, even platinum coatings prepared using traditional magnetron sputtering techniques are increasingly exhibiting inherent technical bottlenecks, becoming a deep-seated contradiction restricting device performance and reliability. The reasons for this are mainly reflected in the following aspects: First, regardless of the plating technology used, there are significant differences in lattice constants and coefficients of thermal expansion between platinum and common conductive substrates (such as copper and nickel alloys).

[0004] When a platinum layer is deposited directly on a substrate or through a single transition layer, this material mismatch generates significant interfacial stress during coating formation. During device operation, especially under the thermal cycling effects of high-frequency, high-power transmission, repeated thermal expansion and contraction between the substrate and coating further accumulate and intensify stress concentration. This makes the bonding interface highly susceptible to fatigue failure, resulting in insufficient adhesion between the coating and the substrate, ultimately leading to easy peeling and detachment. Secondly, traditional DC or RF magnetron sputtering, without advanced control mechanisms, typically struggles to effectively suppress the columnar crystal structure formed during coating growth. This columnar crystal morphology results in numerous vertical grain boundaries and pores within the coating, reducing its density and mechanical strength. This provides a preferential path for stress crack initiation and propagation, further increasing the risk of coating detachment under stress.

[0005] These microstructural defects not only weaken the physical bonding strength of the coating but also indirectly affect its electrical performance in high-frequency signal transmission. For example, when facing high-frequency signals such as 10GHz, discontinuities or microstructural defects in the coating introduce additional signal scattering and loss, manifesting as increased insertion loss, thus affecting communication quality. Even worse, in some high-power applications, microstructural defects or weak bonding in the coating severely weaken its resistance to arc erosion. Once local breakdown or micro-discharge occurs, the coating is easily and rapidly destroyed, leading to device failure. Therefore, while traditional platinum coating technology solves the basic coverage problem, it has already revealed its inherent limitations at the principle level when facing deeper needs such as multi-stress coupling, microstructure optimization, and adaptability to extreme working environments.

[0006] In summary, how to address the aforementioned profound contradictions and develop a platinum composite wire and its plating method that can significantly improve the bonding strength between the platinum coating and the substrate, effectively suppress internal stress concentration, optimize the microstructure of the coating, and ensure excellent performance and long-term reliability in high-frequency and high-power applications has become a key challenge and an urgent technical problem for those skilled in the art. Summary of the Invention

[0007] This invention aims to overcome the problems of insufficient bonding strength and long-term performance stability caused by material lattice mismatch, differences in thermal expansion coefficients, microstructural defects in the coating (such as columnar crystals), and internal stress concentration in existing platinum plating technologies for high-speed, high-frequency communication and high-reliability electronic device applications. To achieve the above-mentioned objectives, this invention provides a platinum composite wire and its plating method. By constructing a multi-layered, gradient functional plating structure and employing advanced pulsed magnetron sputtering technology and precise online process control, the bonding strength between the platinum coating and the conductor substrate, the coating density, the uniformity of the microstructure, and the long-term operational reliability under high-frequency, high-power environments are significantly improved.

[0008] The platinum composite wire provided by this invention comprises, from the inside out, the following components:

[0009] Conductor substrate;

[0010] A first transition layer is densely deposited on the outer surface of the conductor substrate, the first transition layer being composed of any one of the metal materials selected from chromium, titanium, tantalum or nickel, and having a thickness of 20 nanometers to 200 nanometers.

[0011] A second transition layer is densely deposited on the outer surface of the first transition layer. The second transition layer is composed of a platinum-nickel alloy, wherein the percentage content of nickel atoms ranges from 30 atomic percent to 70 atomic percent, the percentage content of platinum atoms ranges from 30 atomic percent to 70 atomic percent, and its thickness ranges from 0.5 micrometers to 3 micrometers.

[0012] And a platinum functional layer densely deposited on the outer surface of the second transition layer, the platinum functional layer being composed of platinum with a purity of not less than 99.999% and having a thickness of 0.5 micrometers to 5 micrometers.

[0013] Preferably, the conductor substrate is selected from oxygen-free copper, beryllium copper alloy or nickel-chromium alloy, the cross-sectional shape of the conductor substrate is circular, square or rectangular, the diameter or equivalent size ranges from 0.1 mm to 5.0 mm, and the surface roughness before plating is controlled between 0.1 μm and 0.5 μm.

[0014] Preferably, the first transition layer is chromium metal with a purity of not less than 99.995%, and the first transition layer has a dense non-columnar crystal structure or a fine crystal structure.

[0015] Preferably, the second transition layer has a nickel atom percentage of 50% and a platinum atom percentage of 50%, and the second transition layer has a fine-grained structure with uniform grain boundary distribution.

[0016] Preferably, the platinum functional layer has a highly dense non-columnar crystal structure or an ultrafine crystal structure with extremely low internal defect density and a surface roughness of less than 0.1 micrometers.

[0017] The present invention provides a platinum composite wire plating method, comprising the following steps:

[0018] Step a, Preparation and pretreatment of the conductor substrate, including continuously introducing the conductor substrate into the online processing system for multi-stage ultrasonic cleaning, followed by argon ion bombardment plasma pre-cleaning in a vacuum chamber;

[0019] Step b, deposition of the first transition layer: After the pretreatment of the conductor substrate is completed, the conductor substrate is introduced into the first sputtering region in a continuous transport state, and the first transition layer is deposited by DC magnetron sputtering technology.

[0020] Step c, deposition of the second transition layer: After the first transition layer is deposited, without breaking the vacuum, the wire substrate is directly transferred to the second sputtering area, and the second transition layer is deposited by high-power pulsed magnetron sputtering or pulsed DC magnetron sputtering technology.

[0021] Step d: Deposition of the platinum functional layer. After the second transition layer is deposited, the conductive substrate is directly transferred to the third sputtering region without breaking the vacuum, and the platinum functional layer is deposited by high-power pulsed magnetron sputtering or pulsed DC magnetron sputtering technology.

[0022] Preferably, in step a, the argon ion bombardment plasma pre-cleaning is performed at a vacuum level better than 5 × 10⁻⁶. -5 The process is carried out in an environment of Pa, by introducing argon gas with a purity of not less than 99.999% and forming argon plasma under the drive of radio frequency or DC power supply, and bombarding the surface of the conductor substrate with ions for 100 to 300 seconds, wherein the energy density of the ion bombardment is controlled at 0.5 W / cm² to 2 W / cm².

[0023] During this process, the conductor substrate is transmitted at a constant speed of 0.1 m / min to 10 m / min, its tension is adjusted in real time by a precision tension controller, and its surface temperature is maintained between room temperature and 100 degrees Celsius by a built-in heating or cooling unit.

[0024] Preferably, in step b, the first sputtering region is equipped with a DC magnetron sputtering target, and the deposition of the first transition layer uses a chromium target with a purity of not less than 99.995%; the deposition process is carried out in an environment with an argon flow rate of 50 standard cubic centimeters / minute to 200 standard cubic centimeters / minute and a total chamber pressure of 0.2 Pa to 0.8 Pa.

[0025] The DC sputtering power density is controlled between 5 W / cm² and 15 W / cm²; the surface temperature of the conductor substrate is precisely controlled between 150°C and 350°C by external heating or internal radiation heating; the deposition rate of the first transition layer is controlled between 0.1 nm / s and 0.5 nm / s.

[0026] Preferably, in step c, the second sputtering region is equipped with a nickel target and a platinum target, or a pre-alloyed nickel-platinum alloy target;

[0027] When using independent nickel and platinum targets for co-sputtering, the composition of the nickel-platinum alloy is precisely controlled by real-time monitoring and adjustment of the sputtering power ratio between the nickel and platinum targets. When using high-power pulsed magnetron sputtering technology, the peak power density of the sputtering power supply is 50 W / cm² to 500 W / cm², the pulse width is 5 μs to 100 μs, the pulse frequency is 50 Hz to 1000 Hz, and the pulse duty cycle is 0.5% to 5%. When using pulsed DC magnetron sputtering technology, the peak power density of the pulse power supply is 15 W / cm² to 50 W / cm², the pulse frequency is 50 kHz to 350 kHz, and the pulse duty cycle is 5% to 30%.

[0028] During the deposition process, the total pressure of the chamber is maintained at 0.1 Pa to 0.6 Pa, the argon flow rate is controlled at 50 standard cubic centimeters per minute to 200 standard cubic centimeters per minute, the DC negative bias or radio frequency bias applied to the surface of the conductor substrate has a voltage value between -50 volts and -200 volts, the surface temperature of the conductor substrate is controlled between 100 degrees Celsius and 400 degrees Celsius, and the deposition rate of the second transition layer is controlled at 0.5 nanometers per second to 2 nanometers per second.

[0029] Preferably, in step d, the third sputtering region is equipped with a platinum target with a purity of not less than 99.999%;

[0030] When using high-power pulsed magnetron sputtering technology, the peak power density of the platinum target is 100 W / cm² to 600 W / cm², the pulse width is 5 μs to 80 μs, the pulse frequency is 100 Hz to 800 Hz, and the duty cycle is 0.2% to 4%.

[0031] When using pulsed DC magnetron sputtering technology, the peak power density of the platinum target is 20 W / cm² to 70 W / cm², the pulse frequency is 80 kHz to 400 kHz, and the duty cycle is 3% to 25%.

[0032] During the deposition process, the total pressure in the chamber is maintained at 0.1 Pa to 0.5 Pa, the argon flow rate is controlled at 50 standard cubic centimeters per minute to 150 standard cubic centimeters per minute, the bias voltage applied to the surface of the conductor substrate is in the range of -30 volts to -150 volts, the surface temperature of the conductor substrate is controlled between 100 degrees Celsius and 350 degrees Celsius, and the deposition rate of the platinum functional layer is controlled between 0.2 nanometers per second and 1.5 nanometers per second.

[0033] Through the above-described technical solution, this invention has achieved significant technical effects and positive progress:

[0034] 1. The multi-layered composite structure significantly improves the bonding strength between the plating layer and the substrate. Traditional platinum plating layers and the conductor substrate exhibit significant differences in lattice constant and coefficient of thermal expansion, leading to high interfacial stress. The first transition layer (such as chromium) introduced in this invention acts as a buffer, exhibiting excellent adhesion to the conductor substrate. More importantly, the nickel-platinum alloy second transition layer serves as a gradient functional layer, with its lattice constant, coefficient of thermal expansion, and mechanical properties forming a smooth transition between the first transition layer and the pure platinum layer. For example, in the Ni50Pt50 alloy, its lattice constant is approximately 0.36 nm, falling between 0.288 nm for pure chromium and 0.392 nm for pure Pt, effectively compensating for the lattice mismatch. Simultaneously, the coefficient of thermal expansion of the Ni-Pt alloy is also between that of the substrate and pure platinum. This gradient stress buffer design greatly reduces stress concentration at each interface, making the plating layer less prone to peeling and detachment under thermal cycling and external mechanical stress, increasing the bonding strength from less than 100 MPa in traditional methods to over 300 MPa.

[0035] 2. The method of depositing the second and third layers using high-power pulsed magnetron sputtering or pulsed DC magnetron sputtering fundamentally improves the microstructure of the coating. Traditional magnetron sputtering tends to form columnar crystal structures, resulting in poor coating density, high porosity, and low mechanical strength. High-power pulsed magnetron sputtering / pulsed DC magnetron sputtering technology uses a high-density, high-energy ion current generated by high-power pulses to continuously bombard the film surface during deposition. This promotes high migration of deposited atoms on the substrate surface, inhibits grain growth along specific directions, breaks the traditional columnar crystal growth pattern, and forms a dense, fine-grained, or ultrafine-grained structure. For example, the platinum functional layer prepared by this invention has an average grain size that can be controlled within the range of 10 nanometers to 50 nanometers, far smaller than the hundreds of nanometers of traditional sputtering. The coating density can reach more than 98% of the theoretical density, and the porosity is reduced to below 0.1%. This dense microstructure effectively reduces the number of internal defects and grain boundaries, thereby improving the coating's cohesion, hardness, and crack propagation resistance, ensuring its ability to resist arc erosion and breakdown in high-frequency, high-power applications.

[0036] 3. The application of the online process monitoring and feedback control system ensures the precision of the composite line coating process and the consistency of product quality. By real-time monitoring of key parameters such as cavity environment, deposition rate, film thickness, plasma state, and substrate temperature, and by implementing closed-loop feedback adjustment, this invention can control the thickness, composition, and microstructure of each layer within an extremely narrow tolerance range. This highly automated and precise control not only significantly improves production efficiency and yield, and reduces manufacturing costs, but more importantly, it ensures that every batch and every meter of the composite line possesses highly uniform electrical and mechanical properties, meeting the stringent repeatability requirements of high-precision electronic devices for material properties.

[0037] 4. The platinum composite wire prepared by this invention exhibits excellent electrical performance in high-frequency signal transmission. The dense, uniform platinum functional layer with a good surface morphology effectively reduces skin effect loss and surface scattering loss in high-frequency signals. In applications at frequencies of 10 GHz and above, compared with traditional plating techniques, the composite wire prepared by this invention has lower insertion loss and higher signal transmission efficiency. For example, under the same geometric dimensions and operating frequency, the insertion loss of the composite wire prepared by this invention can be reduced by 15% to 30%. At the same time, the excellent bonding strength and microstructure stability also ensure that the performance degradation of the composite wire is minimal under long-term operation and thermal cycling conditions, exhibiting excellent long-term reliability. Detailed Implementation

[0038] This invention aims to elaborate on a specific engineering implementation scheme of a platinum composite wire and its plating method, in order to solve the problems of insufficient bonding strength and long-term performance stability caused by material lattice mismatch, differences in thermal expansion coefficients, and microstructural defects in the plating layer in the prior art. This specific embodiment will comprehensively and thoroughly describe the structural composition of the platinum composite wire, the material selection and performance requirements of each functional layer, and its advanced plating method, including the refined pretreatment of the conductor substrate, multi-stage pulsed magnetron sputtering deposition technology, a precise online process monitoring and feedback control system, and optional post-processing techniques, ensuring that those skilled in the art can understand and implement this invention without obstacles based on the content of this disclosure.

[0039] In one specific embodiment, the platinum composite wire provided by the present invention has a core structure that is precisely constructed from the inside out as follows: a conductor substrate, a first transition layer, a second transition layer, and an outermost platinum functional layer. This multi-layered gradient composite structure is the basis for the superior performance of the present invention. It aims to alleviate the differences in physical properties between different material layers step by step, especially the internal stress caused by the mismatch between lattice constants and coefficients of thermal expansion, thereby greatly improving the stability of the overall structure and the bonding strength between the layers.

[0040] As the core carrier of the composite line, the selection of the conductor substrate is crucial to the overall performance. In a preferred embodiment of the present invention, the conductor substrate is made of oxygen-free copper with a purity of 99.99% or higher, to ensure extremely low resistivity and excellent conductivity, thereby minimizing signal attenuation during high-frequency signal transmission.

[0041] In addition, beryllium copper alloys or nickel-chromium alloys can also be selected as conductor substrates depending on specific application requirements. Beryllium copper alloys have excellent elasticity, strength, and conductivity, making them suitable for applications requiring high fatigue resistance and good contact performance; while nickel-chromium alloys, with their excellent high-temperature resistance and corrosion resistance, are particularly suitable for extreme working environments.

[0042] The cross-sectional shape of the conductor substrate is typically circular, but it can also be designed as square or rectangular depending on the specific application to optimize its filling efficiency or heat dissipation performance within a specific space. The diameter or equivalent size of the conductor substrate is precisely controlled between 0.1 mm and 5.0 mm, a range sufficient to cover a wide range of applications from micro-sensor connections to high-power transmission cables, while balancing mechanical strength and electrical transmission performance. Rigorous pretreatment of the conductor substrate surface is crucial before proceeding to the plating process.

[0043] The surface roughness of the conductor substrate must be strictly controlled between 0.1 micrometers and 0.5 micrometers before plating. This refined surface roughness provides sufficient mechanical anchoring points and activated surfaces for the subsequent deposition of the first transition layer, thereby ensuring a strong initial adhesion between each plating layer and effectively avoiding peeling due to poor interfacial bonding during subsequent deposition or long-term service.

[0044] The first transition layer is densely deposited on the outer surface of the conductor substrate. Its core function is to provide an interface with high bonding strength with the conductor substrate, while also serving as a highly efficient diffusion barrier layer between subsequent layers and the substrate. Furthermore, it effectively alleviates the initial interfacial stress caused by direct contact between the substrate and the outermost platinum layer. The first transition layer is composed of a metallic material with excellent adhesion and superior chemical stability, such as any one of chromium, titanium, tantalum, or nickel.

[0045] Chromium, as a preferred material in this invention, has a purity of not less than 99.995%. The chromium layer exhibits excellent wettability and metallurgical bonding with common conductive substrates, such as copper or nickel alloy substrates. This means that, at the atomic scale, chromium atoms can form stable and strong chemical bonds with the substrate atoms. More importantly, the lattice structure of chromium matches the lattice structure of copper or nickel better than that of platinum with these substrates.

[0046] For example, chromium has a lattice constant of about 0.288 nanometers. Although this is different from that of copper or nickel, the introduction of a chromium layer can provide a more gradual lattice transition compared to the direct contact between platinum and copper or nickel, thereby significantly reducing the interfacial stress caused by lattice mismatch during the initial deposition process.

[0047] The thickness of the first transition layer is precisely controlled between 20 nanometers and 200 nanometers. When the thickness of this layer is less than 20 nanometers, its function as a diffusion barrier layer will be greatly reduced, and it will be unable to effectively prevent substrate atoms from diffusing to the outer layer under high temperature or long-term working conditions, which may lead to a decrease in the purity of the outer platinum and affect its performance; at the same time, its effect as a stress buffer layer is also not significant, and it is difficult to effectively relieve the stress between the substrate and the subsequent layers.

[0048] On the other hand, when the thickness of the first transition layer exceeds 200 nanometers, although its blocking effect and stress buffering effect may be slightly enhanced, its own resistivity is relatively high, which may introduce non-negligible additional resistance loss, negatively affecting the overall electrical performance of the composite line, and significantly increasing the plating time and production cost, thereby reducing the economy and practicality of the present invention.

[0049] To minimize the impact of its own defects on the quality of subsequent coatings, the first transition layer should have a dense non-columnar or fine-grained structure. This means that its internal grain orientation is randomly distributed or the size is extremely small, avoiding the columnar crystal structure that is easily formed along the deposition direction by traditional sputtering, thereby reducing the diffusion path and porosity along the grain boundaries.

[0050] The second transition layer is densely deposited on the outer surface of the first transition layer and is the key innovative layer of this invention for solving stress concentration and achieving gradient stress buffering. The second transition layer is composed of a platinum-nickel alloy (Ni-Pt alloy), with its nickel atomic percentage content strictly controlled between 30 and 70 atomic percentages, and the platinum atomic percentage content also correspondingly between 30 and 70 atomic percentages.

[0051] In a highly preferred embodiment of the present invention, the nickel atomic percentage content of the nickel-platinum alloy is precisely set to 50 atomic percentages, and the platinum atomic percentage content is also 50 atomic percentages (i.e., Ni50Pt50).

[0052] This Ni-Pt alloy layer not only inherits the excellent electrical conductivity and chemical stability of both nickel and platinum, but its unique feature lies in the fact that its lattice constant and coefficient of thermal expansion can be precisely positioned between the first transition layer and the outermost pure platinum layer, thus forming a delicate gradient transition in material properties. For example, the lattice constant of pure chromium is approximately 0.288 nm, while that of pure platinum is approximately 0.392 nm; for the Ni50Pt50 alloy, its lattice constant can be controlled to around 0.36 nm through precise alloying. This perfectly constructs a lattice constant gradient system from chromium to nickel-platinum alloy and then to pure platinum, effectively compensating for the stress caused by lattice mismatch between layers.

[0053] Similarly, the coefficient of thermal expansion of Ni-Pt alloys can be designed to be between that of the conductor substrate and pure platinum, thereby effectively mitigating the interfacial stress caused by the difference in thermal expansion between different materials when the composite wire is subjected to temperature changes, and significantly reducing the risk of coating peeling and cracking.

[0054] Furthermore, the Ni-Pt alloy layer also serves as a highly efficient diffusion barrier layer, effectively preventing atoms (especially copper atoms with high mobility) in the conductor substrate from diffusing to the outer pure platinum layer under high temperature or long-term operating conditions.

[0055] This barrier effect is crucial for maintaining the purity and long-term performance stability of the platinum layer, because even trace amounts of copper atoms diffused onto the platinum surface could introduce additional losses in high-frequency signal transmission or accelerate the deterioration of the platinum layer in corrosive environments.

[0056] The thickness of the second transition layer is strictly controlled between 0.5 micrometers and 3 micrometers. When the thickness of the second transition layer is less than 0.5 micrometers, its designed stress buffering and diffusion blocking effects will be insufficient, making it difficult to fully realize the core function of its gradient functional layer.

[0057] When the thickness exceeds 3 micrometers, although the functionality may be enhanced, it may lead to a significant decrease in the overall flexibility of the composite line, especially in applications that require frequent bending or winding, and will significantly increase plating time and production costs, reducing production efficiency.

[0058] To further enhance its resistance to stress cracking and external mechanical damage, the second transition layer is designed and fabricated to have a fine-grained structure and highly uniform grain boundary distribution, thereby effectively dispersing and absorbing stress and reducing the formation of stress concentration points.

[0059] The platinum functional layer is densely deposited on the outer surface of the second transition layer and is the final functional surface of the composite line of the present invention, designed to provide superior electrical, chemical and physical properties to meet the stringent requirements of high-performance electronic devices.

[0060] The platinum functional layer is composed of ultra-high purity platinum with a purity of not less than 99.999%. Platinum is renowned for its excellent electrical conductivity, excellent chemical inertness, superior corrosion resistance, and oxidation resistance, making it an indispensable material in fields such as high-frequency communication, precision sensors, medical devices, and aerospace.

[0061] The thickness of the platinum functional layer is precisely controlled between 0.5 micrometers and 5 micrometers. When the thickness of the platinum functional layer is less than 0.5 micrometers, its function as the final protective layer may be insufficient. Its corrosion resistance, oxidation resistance, and coverage of the skin depth of high-frequency signals will be limited, which may lead to excessive skin effect loss in high-frequency signal transmission and affect its long-term reliability in complex environments.

[0062] On the other hand, when the thickness of the platinum functional layer exceeds 5 micrometers, although its protective performance may be improved, this will lead to significant material waste, greatly increase production costs, and may negatively affect the overall flexibility of the composite line, making it difficult to bend or manipulate. To ensure the superior performance of the final product, the platinum functional layer must have a highly dense non-columnar crystalline structure or an ultrafine crystalline structure, and its internal defect density must be extremely low.

[0063] This highly dense microstructure minimizes losses in high-frequency signal transmission because electromagnetic waves primarily propagate along the material surface at high frequencies, and any surface or near-surface defects can lead to signal scattering and energy loss. Simultaneously, the extremely low defect density significantly improves the long-term reliability of the coating in complex environments, effectively preventing the penetration of corrosive media and crack propagation.

[0064] In addition, its surface roughness should be strictly controlled to less than 0.1 micrometers. Such a smooth surface is crucial for reducing skin effect loss and surface scattering effect in high-frequency signal transmission, thereby ensuring the excellent signal transmission efficiency of the composite line at 10 GHz or even higher frequencies.

[0065] This invention also provides a platinum composite wire deposition method, the core innovation of which lies in the use of highly optimized multi-stage pulsed magnetron sputtering technology, combined with a real-time process monitoring and feedback control system, to achieve precise and dynamic control over the deposition process, microstructure, and interface quality of each layer. The method includes the following series of closely linked and synergistic steps:

[0066] Step 1: Preparation and pretreatment of conductor substrate:

[0067] The conductor substrate is continuously introduced into an integrated online processing system. This system first performs multi-stage ultrasonic cleaning on the conductor substrate. This cleaning process typically uses deionized water preheated to 50 to 70 degrees Celsius, combined with a specialized cleaning agent containing surfactants and weakly alkaline components.

[0068] The cleaning agent effectively emulsifies and dissolves organic matter, grease, and cutting fluid residue on the surface of the conductors, while the cavitation effect of the ultrasound efficiently peels off and removes tiny particulate contaminants adhering to the surface. After cleaning, the conductor substrate is thoroughly rinsed with pure deionized water through multiple rinsing tanks to remove all cleaning agent residue, ensuring a clean and spotless surface.

[0069] Subsequently, the wire substrate, without exposure to the atmospheric environment, is smoothly transported into a high-vacuum chamber via a vacuum transfer system. Inside the vacuum chamber, the wire substrate undergoes a crucial argon-ion bombardment plasma pre-cleaning step before entering the actual sputtering area. This pre-cleaning process is performed at a vacuum level better than 5 × 10⁻⁶. -5 The cleaning is carried out in an ultra-high vacuum environment to minimize the impact of residual gas on the cleaning effect.

[0070] By introducing high-purity argon gas (99.999%) and exciting it into a stable argon plasma under the drive of an RF or DC power supply, the surface of the conductor substrate is bombarded with low-energy ions for 100 to 300 seconds. The energy density of the ion bombardment is precisely controlled between 0.5 W / cm² and 2 W / cm².

[0071] Within this energy range, argon ions can effectively physically bombard and remove the native oxide layer, adsorbed gas molecules, and residual trace contaminants from the surface of the conductor substrate, while avoiding excessive surface damage, etching, or roughening. This provides an atomically clean surface for the deposition of subsequent layers, significantly improving the initial adhesion and bonding strength of the subsequent films.

[0072] Throughout the pretreatment process, the conductor substrate is precisely wound onto multiple precision guide rollers and transmitted at a constant speed of 0.1 m / min to 10 m / min. Its tension is dynamically adjusted in real time by a high-precision tension controller to ensure that the conductor maintains a stable position and shape throughout the treatment process, avoiding vibration, deviation, or uneven coating caused by tension fluctuations.

[0073] Furthermore, during the pretreatment stage, the surface temperature of the conductor substrate is pre-regulated by a built-in heating or cooling unit to maintain it between room temperature and 100 degrees Celsius. This temperature range is designed to avoid substrate oxidation due to excessively high temperatures, or to prevent the migration rate of subsequently deposited atoms on the substrate surface and the initial nucleation quality from being too low.

[0074] Step 2: Deposition of the first transition layer:

[0075] After the fine pretreatment of the conductor substrate is completed, the conductor substrate directly enters the first sputtering region of the integrated system in a continuous transport state to begin depositing the first transition layer. The first sputtering region is equipped with a DC magnetron sputtering target.

[0076] Preferably, when the first transition layer is chromium, an ultra-high purity chromium target with a purity of not less than 99.995% is used to avoid the introduction of impurities. The deposition process is carried out in a pure argon atmosphere, and the argon flow rate is precisely controlled between 50 standard cubic centimeters / minute and 200 standard cubic centimeters / minute to ensure a stable plasma environment.

[0077] The total chamber pressure is maintained between 0.2 Pa and 0.8 Pa during this stage. This pressure range is conducive to the formation of a stable glow discharge and ensures a moderate mean free path of the sputtered particles, thereby obtaining a uniform coating. The DC sputtering power density is precisely controlled between 5 W / cm² and 15 W / cm². Too low a power may result in a slow deposition rate or an incomplete film density, while too high a power may cause target overheating or excessively high particle energy, leading to a decrease in film quality.

[0078] During this stage, the surface temperature of the conductor substrate is precisely controlled by an external induction heating or internal radiant heating system, maintaining it between 150 and 350 degrees Celsius. Appropriate substrate temperature significantly promotes the migration and diffusion of chromium atoms on the substrate surface, enhancing the interatomic bonding strength between chromium and the substrate, thereby forming a dense and well-crystallized film and maximizing adhesion to the substrate.

[0079] The deposition rate of the first transition layer is precisely controlled by adjusting the sputtering power and wire transfer speed in real time, so that its final thickness can accurately reach the design requirement of 20 nanometers to 200 nanometers. Typically, the deposition rate is controlled between 0.1 nanometers / second and 0.5 nanometers / second to ensure coating uniformity and density.

[0080] Step 3: Deposition of the second transition layer:

[0081] After the first transition layer is deposited, the conductor substrate enters the second sputtering region directly in continuous transport mode without vacuum breaking to begin depositing the second transition layer. The second sputtering region is one of the key innovations of this method, and it is equipped with a nickel target and a platinum target, or a pre-alloyed nickel-platinum alloy target.

[0082] In a preferred embodiment of the present invention, co-sputtering is performed using independent nickel and platinum targets. By controlling the sputtering power of the two targets separately, precise and dynamic control of the nickel-platinum alloy composition can be achieved, thereby accurately adjusting its lattice constant and thermal expansion coefficient to achieve the best gradient buffering effect.

[0083] The deposition of the second transition layer employs advanced high-power pulsed magnetron sputtering or pulsed DC magnetron sputtering technology. Compared with traditional DC magnetron sputtering, these technologies can significantly improve plasma ionization rate and sputtered particle energy, thereby fundamentally improving the microstructure and mechanical properties of the coating.

[0084] In high-power pulsed magnetron sputtering mode, the sputtering power supply bombards the target with short pulses at extremely high instantaneous power. The peak power density can reach 50 W / cm² to 500 W / cm², while the width of a single pulse is precisely controlled between 5 microseconds and 100 microseconds.

[0085] The pulse frequency range is set from 50 Hz to 1000 Hz, and the pulse duty cycle is controlled between 0.5% and 5%. This high instantaneous power can generate extremely high-density plasma, with an ion density reaching 10-1. 13 Units per cubic centimeter to 10 14 The plasma density is several orders of magnitude higher than that of traditional DC sputtering, resulting in a higher proportion of charged ions in the particles deposited on the substrate surface.

[0086] These high-energy ions, with average energies ranging from tens to hundreds of electron volts, can effectively suppress columnar crystal growth in thin films and promote lateral migration and recrystallization of deposited atoms when they reach the substrate surface through inelastic collisions and momentum transfer, thereby forming dense thin films with ultrafine grains or even amorphous structures.

[0087] In addition, high-energy ion bombardment can effectively clean the film surface, reduce defects, significantly improve the film's hardness and cohesion, and reduce internal stress.

[0088] In pulsed DC magnetron sputtering mode, the peak power density of the pulsed power supply is typically lower than that of high-power pulsed magnetron sputtering, but still much higher than that of conventional DC sputtering, with peak power densities ranging from 15 W / cm² to 50 W / cm². The pulse frequency range is even higher, typically from 50 kHz to 350 kHz, while the pulse duty cycle is controlled between 5% and 30%.

[0089] Pulsed DC magnetron sputtering technology can also improve plasma density and sputtered particle ionization rate. Although the average ion energy may be slightly lower than that of high-power pulsed magnetron sputtering, it can still effectively suppress columnar crystal growth and significantly improve the compactness, hardness and adhesion of the film through its high-frequency ion bombardment and optimization of sputtered particle energy distribution.

[0090] During the deposition of the second transition layer, the total chamber pressure is typically maintained between 0.1 Pa and 0.6 Pa to ensure stable plasma and optimized deposition conditions. The argon flow rate is controlled between 50 standard cubic centimeters per minute and 200 standard cubic centimeters per minute. A precise DC negative bias or radio frequency bias is applied to the surface of the conductor substrate, with voltage values ​​between -50 volts and -200 volts.

[0091] The bias voltage attracts high-energy ions from the plasma to bombard the surface of the deposited film. This ion bombardment further increases the density of the film, promotes grain refinement, and effectively alleviates and adjusts residual stress within the film, thereby preventing film cracking or peeling caused by stress concentration.

[0092] The surface temperature of the conductor substrate is precisely controlled between 100 and 400 degrees Celsius by an internal temperature control system to optimize atomic mobility and crystal growth kinetics, ensuring that the Ni-Pt alloy layer forms an ideal fine-grained structure.

[0093] For compositional control of the nickel-platinum alloy layer, when using co-sputtering, this is achieved by real-time monitoring and precise adjustment of the sputtering power ratio of the nickel and platinum targets. For example, if the sputtering power of the nickel target is set to P_Ni and the sputtering power of the platinum target is set to P_Pt, then by adjusting the P_Ni / P_Pt ratio, the atomic percentage content of nickel and platinum in the deposited film can be precisely controlled, thereby achieving fine-tuning of the physical properties of the alloy layer.

[0094] The deposition rate of the second transition layer is precisely controlled between 0.5 nm / s and 2 nm / s to ensure that its final thickness can accurately meet the design requirements of 0.5 μm to 3 μm.

[0095] Step 4: Deposition of the platinum functional layer:

[0096] After the second transition layer is deposited, the conductor substrate, without breaking the vacuum, directly enters the third sputtering region in continuous transport mode to begin depositing the outermost platinum functional layer.

[0097] The third sputtering region is equipped with a high-purity platinum target to ensure that the deposited platinum layer has extremely high purity.

[0098] The deposition of the platinum functional layer also employs high-power pulsed magnetron sputtering or pulsed DC magnetron sputtering technology. The sputtering parameters are optimized and adjusted according to the material properties of pure platinum and the required coating performance to obtain the best density, surface morphology and electrical properties.

[0099] In high-power pulsed magnetron sputtering mode, the peak power density of the platinum target can reach 100 W / cm² to 600 W / cm², the single pulse width is 5 μs to 80 μs, the pulse frequency ranges from 100 Hz to 800 Hz, and the duty cycle is controlled between 0.2% and 4%. These parameters are adjusted to maximize the energy and ionization rate of platinum ions, thereby forming an ultrafine-grained, highly dense platinum layer on the substrate surface.

[0100] In pulsed DC magnetron sputtering mode, the peak power density of the platinum target can reach 20 W / cm² to 70 W / cm², with a pulse frequency range of 80 kHz to 400 kHz and a duty cycle controlled between 3% and 25%. Although the ion energy may be slightly lower than that of high-power pulsed magnetron sputtering, its high frequency and optimized energy distribution can still effectively suppress columnar crystal growth, ensuring a high-quality platinum layer.

[0101] During the platinum functional layer deposition process, the total chamber pressure was maintained between 0.1 Pa and 0.5 Pa, and the argon flow rate was controlled between 50 standard cubic centimeters per minute and 150 standard cubic centimeters per minute. The lower total chamber pressure helps reduce the scattering of sputtered particles, allowing more high-energy particles to reach the substrate surface. The bias voltage applied to the wire substrate surface ranged from -30 volts to -150 volts, designed to further attract ion bombardment, improving film density and surface smoothness.

[0102] The surface temperature of the conductor substrate is precisely controlled between 100°C and 350°C during this stage to ensure that the platinum layer has high density, extremely low internal defect density, and excellent surface morphology, thereby guaranteeing low-loss characteristics for high-frequency signal transmission. The deposition rate of the platinum functional layer is precisely controlled between 0.2 nm / s and 1.5 nm / s, so that its final thickness can accurately meet the design requirements of 0.5 μm to 5 μm.

[0103] Step 5: Online process monitoring and feedback control:

[0104] Throughout the coating process, this invention employs a highly integrated online process monitoring and feedback control system to ensure that the quality and repeatability of each coating layer meet the highest standards. This system is a closed-loop system composed of multiple precision sensors and intelligent control units, capable of acquiring key process parameters in real time and dynamically adjusting them according to a preset algorithm. Specifically, the system includes, but is not limited to, the following components:

[0105] a. Residual Gas Analyzer: This device is deployed in a key location within the sputtering chamber and can monitor the vacuum level, background gas composition, and the content of potential contaminants within the chamber in real time. Using mass spectrometry, the residual gas analyzer accurately identifies residual gases such as hydrogen, water vapor, nitrogen, and oxygen, as well as any organic contaminants that may affect the coating quality.

[0106] If any parameter deviates from the preset threshold, the system will immediately activate an audible and visual alarm and automatically adjust the relevant process parameters according to the preset control strategy, such as extending the pre-vacuum time, increasing the baking temperature, or adjusting the gas flow rate, so as to ensure that the deposition process is always carried out in a clean and stable vacuum environment.

[0107] b. Quartz crystal microbalances or optical interferometers for film thickness monitoring: These devices are deployed at key locations in each sputtering area to monitor the deposition rate and instantaneous thickness of each thin film layer in real time. Quartz crystal microbalances estimate film thickness by measuring changes in the vibration frequency of a quartz crystal, while optical interferometers accurately calculate film thickness by detecting periodic changes in the intensity or wavelength of reflected light during film growth.

[0108] The system compares the real-time monitored film thickness data with the preset target value within milliseconds, and automatically adjusts the corresponding sputtering power or wire transfer speed through a PID (proportional-integral-derivative) controller. For example, if the deposition rate is detected to be too fast, the target power will be slightly reduced or the wire transfer speed will be increased; if the rate is too slow, the opposite will be done. This closed-loop control ensures that the thickness accuracy of each film layer is within ±5%, thereby guaranteeing the consistency of product performance.

[0109] c. Optical Emission Spectrometer: An optical emission spectrometer is used to analyze the atomic, ionic, and molecular emission lines emitted by the plasma glow discharge in the sputtering chamber in real time. By accurately identifying these characteristic spectral lines, such as the specific emission intensity of argon atoms and the characteristic peaks of sputtered metal atoms, the optical emission spectrometer can non-invasively monitor the sputtering state of the target material, the ionization rate of the working gas, and the stability of the plasma environment.

[0110] For example, monitoring the emission intensity of argon atoms at a specific wavelength can indirectly assess plasma density, while monitoring the intensity of characteristic spectral lines of sputtered metal atoms can reflect the sputtering rate in real time, providing a basis for feedback adjustment of sputtering power. Real-time monitoring by optical emission spectrometers helps to promptly detect anomalies such as target poisoning and plasma instability, thereby enabling immediate adjustments to process parameters.

[0111] d. Infrared thermometers or thermocouple arrays: These temperature sensors are integrated near the wire path in each sputtering region for real-time, non-contact or contact monitoring of the wire substrate surface temperature in each sputtering region. The acquired temperature data is transmitted in real time to a PID controller, which, in conjunction with the heating or cooling unit, strictly controls the wire surface temperature deviation within ±10 degrees Celsius. Precise temperature control is crucial for promoting atomic migration, optimizing thin film crystal structure, releasing stress, and ensuring good bonding between layers.

[0112] e. Precision Tension Control System: This system ensures that the tension of the wire remains constant throughout the entire coating path by using multiple tension sensors along the wire transmission path and a servo motor-driven winding / unwinding device. Constant tension prevents wire vibration and deviation caused by tension fluctuations, thereby preventing uneven coating thickness or substrate deformation. Its stability is especially crucial for coating quality under high-speed transmission conditions.

[0113] f. Image Recognition and Defect Detection System: After the conductor has completed the deposition of all coating layers and left the main sputtering chamber, the surface of the composite line is 100% inspected online using a high-speed linear array camera and advanced image processing algorithms. This system can quickly identify and locate macroscopic defects such as microcracks, voids, peeling, and scratches. Once a defect is detected, the system immediately marks it and generates a detailed quality assessment report, indicating the defect type, location, and severity, providing a basis for subsequent quality analysis and process improvement.

[0114] The feedback control system transmits massive amounts of data collected in real time from all the aforementioned sensors to a central processing unit. Through pre-programmed complex control algorithms, including but not limited to PID control, fuzzy control, or neural network control algorithms, the data is analyzed in real time, and corresponding control signals are generated based on the analysis results.

[0115] These control signals are then sent to actuators such as the sputtering power supply, bias power supply, gas flow controller, wire transmission speed controller, and temperature control unit for millisecond-level real-time adjustments. This highly automated closed-loop precision control not only significantly improves production efficiency and yield, and reduces manufacturing costs, but more importantly, it ensures that every batch, and even every meter, of the composite line produced has highly consistent electrical, mechanical, and surface properties, thereby meeting the stringent repeatability requirements of high-precision electronic devices for material properties.

[0116] Step 6: Optional post-processing:

[0117] After all the coating layers have been deposited, the platinum composite wire can undergo a selective post-treatment to further optimize its overall performance. This post-treatment typically includes vacuum annealing or plasma annealing. The annealing process is performed at a vacuum level better than 1×10⁻⁶. -5 The annealing process is carried out under ultra-high vacuum to avoid oxidation or the introduction of other contaminants at high temperatures. The annealing temperature ranges from 300°C to 600°C, and the duration ranges from 10 minutes to 60 minutes.

[0118] This post-processing step effectively promotes the release of residual stress within the coating, especially the compressive or tensile stress caused by atomic bombardment and growth mode during sputtering deposition. Through thermal input, atoms gain sufficient energy to migrate, further optimizing the grain structure within the film, such as homogenizing or slightly increasing grain size and reducing grain boundary density. This improves the metallurgical bonding strength between layers and the overall density of the coating.

[0119] Furthermore, annealing can eliminate some microscopic defects, thereby maximizing the long-term reliability and electrical performance of the composite wire, ensuring its stability even under extreme operating environments. During annealing, the rate of temperature rise and fall should be precisely controlled to avoid excessively rapid temperature changes introducing new thermal stresses, which could adversely affect the coating structure.

[0120] In summary, this invention, through a unique composite layer design combined with advanced pulsed magnetron sputtering technology and a precise online control system, comprehensively solves the deep-seated contradictions in existing platinum plating technologies regarding interface stress, microstructure, bonding strength, and high-frequency performance. It provides a high-performance, high-reliability platinum composite line solution for fields such as high-speed, high-frequency communication, precision sensors, and aerospace.

[0121] The specific implementation principle of the present invention will be further explained below with reference to the embodiments and comparative examples.

[0122] Example 1: Implementation of the Platinum Composite Wire and its Plating Method of the Present Invention

[0123] This embodiment aims to illustrate in detail a platinum composite wire prepared according to the technical solution of the present invention, its specific plating process parameters, and its final performance.

[0124] First, oxygen-free copper (OFC, 99.998% purity) wires with a diameter of 0.5 mm were selected as the substrate. Before plating, the wire substrate was subjected to three-stage ultrasonic cleaning (using pure water and alkaline cleaning agent, temperature 60℃, 5 minutes per stage), followed by ion bombardment cleaning in a vacuum pretreatment chamber.

[0125] The vacuum level of the cleaning chamber is stabilized at 3×10 -5The ion bombardment was performed using high-purity argon gas (99.999%), driven by radio frequency power, with an energy density set at 1.0 W / cm² and a bombardment time of 180 seconds. The wire transmission speed was set at 0.5 m / min, and the tension was maintained at 5 N. The substrate surface temperature was preset to 50 degrees Celsius. After pretreatment, the wire surface roughness Ra reached 0.15 μm.

[0126] Next, the first transition layer (chromium layer) was deposited. The wire substrate entered the first sputtering region, which was equipped with a high-purity (99.998%) chromium target. Deposition was carried out in an argon atmosphere with an argon flow rate of 100 standard cubic centimeters per minute and a total chamber pressure of 0.5 Pa. The DC sputtering power density was set to 10 W / cm². The surface temperature of the wire substrate was controlled at 250°C. The deposition rate was controlled at 0.2 nm / s, and the final chromium layer thickness reached 100 nm. X-ray diffraction analysis showed that the chromium layer exhibited a dense, fine-grained structure with a grain size of approximately 20 nm.

[0127] Subsequently, without breaking the vacuum, the wire substrate enters the second sputtering region to deposit the second transition layer. This region is equipped with separate nickel (99.995%) and platinum (99.995%) targets, using high-power pulsed magnetron sputtering co-sputtering technology.

[0128] The peak power density of the nickel target was set to 200 W / cm², and the peak power density of the platinum target was set to 200 W / cm² to ensure the atomic percentage composition of Ni50Pt50.

[0129] The pulse width is 50 microseconds, the pulse frequency is 200 Hz, and the duty cycle is 2%. The total chamber pressure is 0.3 Pa, and the argon flow rate is 120 standard cubic centimeters per minute. A DC bias of -100 volts is applied to the surface of the conductor substrate. The surface temperature is controlled at 300 degrees Celsius.

[0130] The deposition rate was controlled at 1.0 nm / s, resulting in a final nickel-platinum alloy layer thickness of 1.5 μm. Transmission electron microscopy revealed that the Ni-Pt alloy layer exhibited a uniform ultrafine-grained structure with an average grain size of approximately 15 nm and a density reaching 98.5% of the theoretical density.

[0131] Next, without breaking the vacuum, the process proceeds to the third sputtering region to deposit the outermost platinum functional layer. This region is equipped with a high-purity (99.999%) platinum target and also employs high-power pulsed magnetron sputtering technology.

[0132] The platinum target peak power density was set to 400 W / cm², pulse width to 40 μs, pulse frequency to 300 Hz, and duty cycle to 1.2%. The total chamber pressure was 0.25 Pa, and the argon flow rate was 80 standard cubic centimeters per minute. A DC bias of -80 volts was applied to the surface of the conductor substrate. The surface temperature was controlled at 280 degrees Celsius.

[0133] The deposition rate was controlled at 0.8 nm / s, resulting in a final platinum functional layer thickness of 2.0 μm. Scanning electron microscopy and atomic force microscopy results showed that the surface roughness Ra of the platinum functional layer was less than 0.08 μm, the structure was highly dense, with no visible micropores or cracks, and the average grain size was approximately 25 nm.

[0134] Throughout the plating process, the online monitoring system operates continuously. A residual gas analyzer monitors residual gas in real time and automatically adjusts vacuum pump parameters when slightly elevated water vapor content is detected.

[0135] A quartz crystal microbalance precisely monitors the deposition rate of each layer and automatically fine-tunes the sputtering power; an optical emission spectrometer analyzes the plasma glow in real time to ensure the normal operation of the target material.

[0136] The infrared thermometer precisely controls the temperature of the conductor, with a deviation of less than ±5 degrees Celsius; the precision tension system maintains a constant tension of 5 Newtons ±0.1 Newtons.

[0137] The prepared platinum composite wire was subjected to vacuum annealing. Annealing was carried out under a vacuum of 1×10^-6 Pa at a temperature of 450 degrees Celsius for 30 minutes. The temperature rise and fall rate was controlled at 5 degrees Celsius / minute.

[0138] The performance test results of the platinum composite thread prepared by the above process are as follows:

[0139] Bond strength: The bond strength between the platinum plating and the substrate was measured to be as high as 350 MPa through scratch and pull tests.

[0140] Microstructure: The average grain size of the platinum functional layer is 25 nanometers, the density reaches 99.2% of the theoretical density, and the porosity is less than 0.05%.

[0141] Hardness: The Vickers hardness of the platinum functional layer reaches 200 HV.

[0142] Electrical performance: Insertion loss is 0.05 dB / m at 10 GHz.

[0143] Surface roughness: Ra value 0.07 micrometers.

[0144] Comparative Example 1: Conventional DC magnetron sputtering platinum wire. To compare the advantages of the present invention, this comparative example prepared a wire in which platinum was directly plated onto a copper substrate using conventional DC magnetron sputtering technology.

[0145] The same oxygen-free copper conductor substrate of the same specification was selected and pretreated in the same way, such as ultrasonic cleaning and argon ion bombardment, but the bombardment energy density was 0.5 W / cm² and the time was 120 seconds.

[0146] In the same sputtering chamber, a 2.0-micrometer-thick pure platinum layer was deposited directly on a copper substrate using DC magnetron sputtering. The sputtering parameters were set as follows: total chamber pressure 0.8 Pa, argon flow rate 150 standard cubic centimeters / minute, and DC sputtering power density 8 watts / square centimeter.

[0147] No bias voltage was applied to the substrate surface, and the temperature was controlled at room temperature (approximately 25 degrees Celsius). The deposition rate was approximately 0.5 nanometers per second. No transition layer deposition or post-treatment was performed.

[0148] The performance test results of the platinum wire prepared by this process are as follows:

[0149] Bond strength: The measured bond strength between the platinum plating and the substrate was approximately 80 MPa. Significant cracking and peeling occurred in the plating during bending and thermal cycling tests.

[0150] Microstructure: The average grain size of the platinum functional layer is about 200 nanometers, exhibiting a typical columnar crystal structure with a density of about 90% of the theoretical density and a porosity of about 2%.

[0151] Hardness: The Vickers hardness of the platinum functional layer is approximately 150 HV (with a load of 0.05 Newtons).

[0152] Electrical performance: Insertion loss is 0.08 dB / m at 10 GHz.

[0153] Surface roughness: Ra value 0.25 micrometers.

[0154] Data Comparison: The following table clearly compares the differences between this embodiment and the comparative example in key performance indicators:

[0155] Performance indicators Example 1 (Invention) Comparative Example 1 (Traditional Method) Increase in magnitude (compared to the comparative example) Bond strength (MPa) 350 80 Approximately 337.5% Average grain size of platinum layer (nm) 25 200 Reduced by approximately 87.5% Platinum layer density (% of theoretical density) 99.2 90 An increase of approximately 10.2%. Porosity of platinum layer (%) <0.05 2 Reduced by approximately 97.5% Vickers hardness (HV) of platinum layer 200 150 An increase of approximately 33.3%. Insertion loss at 10 GHz (dB / m) 0.05 0.08 A decrease of approximately 37.5% Surface roughness Ra (µm) of the platinum layer 0.07 0.25 Reduced by approximately 72%

[0156] As can be seen from the data comparison above, this invention successfully overcomes the inherent defects of traditional platinum plating technology in terms of interface stress, microstructure and bonding strength by introducing a multi-level gradient composite structure, adopting advanced pulsed magnetron sputtering technology and implementing precise online process monitoring and feedback control.

[0157] The platinum composite wire prepared by this invention achieves significant improvements in bonding strength, coating density, microstructure uniformity, hardness, and high-frequency electrical performance. Its superior performance makes it an ideal wire solution for high-speed, high-frequency communication and high-reliability electronic devices, demonstrating tremendous technological advancement and application prospects.

Claims

1. A platinum-gold composite wire, characterized by, The structure comprises from inside to outside: a wire substrate; a first transition layer closely deposited on the outer surface of the wire substrate, the first transition layer is composed of any one metal material selected from chromium, titanium, tantalum or nickel, and the thickness is 20 nanometers to 200 nanometers; a second transition layer closely deposited on the outer surface of the first transition layer, the second transition layer is composed of platinum-nickel alloy, wherein the atomic percentage content of nickel ranges from 30 atomic percent to 70 atomic percent, the atomic percentage content of platinum ranges from 30 atomic percent to 70 atomic percent, and the thickness is 0.5 micrometers to 3 micrometers; and a platinum-gold functional layer closely deposited on the outer surface of the second transition layer, the platinum-gold functional layer is composed of platinum-gold with a purity of not less than 99.999%, and the thickness is 0.5 micrometers to 5 micrometers.

2. The platinum alloy wire of claim 1, wherein The wire substrate is selected from any one of oxygen-free copper, beryllium copper alloy or nickel-chromium alloy, the cross-sectional shape of the wire substrate is circular, square or rectangular, the diameter or equivalent size ranges from 0.1 millimeter to 5.0 millimeters, and the surface roughness before plating is controlled between 0.1 micrometers to 0.5 micrometers.

3. The platinum alloy wire of claim 1, wherein The first transition layer is chromium metal with a purity of not less than 99.995%, and the first transition layer has a dense non-columnar crystal structure or fine crystal structure.

4. The platinum alloy wire according to claim 1 or 3, characterized by The second transition layer has an atomic percentage content of nickel of 50 atomic percent and an atomic percentage content of platinum of 50 atomic percent, and the second transition layer adopts a fine crystal structure with uniform grain boundary distribution.

5. The platinum alloy wire of claim 1, wherein The platinum-gold functional layer has a highly dense non-columnar crystal structure or ultra-fine crystal structure, with extremely low internal defect density, and a surface roughness of less than 0.1 micrometers.

6. A plating method for a platinum-gold composite wire, characterized by, The method comprises the following steps: Step a, preparation and pretreatment of the wire substrate, including continuously introducing the wire substrate into an online processing system, performing multi-stage ultrasonic cleaning, and then performing argon ion bombardment plasma pre-cleaning in a vacuum chamber; Step b, deposition of the first transition layer, after the pretreatment of the wire substrate is completed, the wire substrate is introduced into a first sputtering area in a continuous transmission state, and the first transition layer is deposited by direct current magnetron sputtering technology; Step c, deposition of the second transition layer, after the deposition of the first transition layer is completed, the wire substrate is directly transmitted to a second sputtering area without breaking the vacuum, and the second transition layer is deposited by high-power pulsed magnetron sputtering or pulsed direct current magnetron sputtering technology; Step d, deposition of the platinum-gold functional layer, after the deposition of the second transition layer is completed, the wire substrate is directly transmitted to a third sputtering area without breaking the vacuum, and the platinum-gold functional layer is deposited by high-power pulsed magnetron sputtering or pulsed direct current magnetron sputtering technology.

7. The plating method according to claim 6, wherein The argon ion bombardment plasma pre-cleaning in step a is performed at a vacuum degree of better than 5 x 10 -5 The surface of the wire substrate is subjected to ion bombardment for 100 to 300 seconds by introducing argon gas with a purity of not less than 99.999% and forming argon plasma under the driving of a radio frequency or direct current power source, and the energy density of the ion bombardment is controlled at 0.5 to 2 W / cm2. And in this process, the wire substrate is constantly transmitted at a speed of 0.1 meters / minute to 10 meters / minute, the tension is adjusted in real time by a precision tension controller, and the surface temperature is maintained between room temperature and 100 degrees Celsius by an embedded heating or cooling unit.

8. The plating method according to claim 6, wherein In the step b, the first sputtering area is equipped with a direct current magnetron sputtering target, and the deposition of the first transition layer uses a chromium target material with a purity of not less than 99.995%. The deposition process is carried out in an environment with argon flow rate of 50 standard cubic centimeters per minute to 200 standard cubic centimeters per minute and chamber total pressure of 0.2 Pa to 0.8 Pa; The direct current sputtering power density is controlled at 5 W / cm2 to 15 W / cm2; the surface temperature of the wire substrate is precisely controlled at 150℃ to 350℃ through external heating or internal radiation heating; The deposition rate of the first transition layer is controlled at 0.1 nm / s to 0.5 nm / s.

9. The plating method according to claim 6, wherein In step c, the second sputtering area is equipped with a nickel target and a platinum target, or a pre-alloyed nickel-platinum alloy target; When independent nickel target and platinum target are used for co-sputtering, the composition of the nickel-platinum alloy is precisely controlled by real-time monitoring and adjusting the sputtering power ratio of the nickel target and the platinum target; When high-power pulsed magnetron sputtering technology is used, the peak power density of the sputtering power source is 50 W / cm2 to 500 W / cm2, the pulse width is 5 μs to 100 μs, the pulse frequency is 50 Hz to 1000 Hz, and the pulse duty cycle is 0.5% to 5%; When pulse direct current magnetron sputtering technology is used, the peak power density of the pulse power source is 15 W / cm2 to 50 W / cm2, the pulse frequency is 50 kHz to 350 kHz, and the pulse duty cycle is 5% to 30%; In the deposition process, the chamber total pressure is maintained at 0.1 Pa to 0.6 Pa, the argon flow rate is controlled at 50 standard cubic centimeters per minute to 200 standard cubic centimeters per minute, a direct current negative bias or radio frequency bias is applied to the surface of the wire substrate, the voltage value is between -50 V and -200 V, the surface temperature of the wire substrate is controlled at 100℃ to 400℃, and the deposition rate of the second transition layer is controlled at 0.5 nm / s to 2 nm / s.

10. The plating method according to claim 6, wherein In step d, the third sputtering area is equipped with a platinum target with a purity of not less than 99.999%; When high-power pulsed magnetron sputtering technology is used, the peak power density of the platinum target is 100 W / cm2 to 600 W / cm2, the pulse width is 5 μs to 80 μs, the pulse frequency is 100 Hz to 800 Hz, and the duty cycle is 0.2% to 4%; When pulse direct current magnetron sputtering technology is used, the peak power density of the platinum target is 20 W / cm2 to 70 W / cm2, the pulse frequency is 80 kHz to 400 kHz, and the duty cycle is 3% to 25%; In the deposition process, the chamber total pressure is maintained at 0.1 Pa to 0.5 Pa, the argon flow rate is controlled at 50 standard cubic centimeters per minute to 150 standard cubic centimeters per minute, a bias voltage is applied to the surface of the wire substrate, the voltage range is -30 V to -150 V, the surface temperature of the wire substrate is controlled at 100℃ to 350℃, and the deposition rate of the platinum functional layer is controlled at 0.2 nm / s to 1.5 nm / s.