Preparation Method of HDMI Common-Mode Rejector Made of Nanocrystalline Material

Abstract

The present invention provides a preparation method of an HDMI common-mode suppressor made of nanocrystalline materials, which relates to the technical field of electronic component preparation. To meet the stringent requirements of HDMI high-frequency and high-speed signals for common-mode noise suppression, in this method, on a microstructured substrate, a multilayer heterogeneous magnetic film with a gradient interface is constructed by multi-target magnetron sputtering; a selective energy field-assisted annealing technique is adopted to achieve precise nanocrystallization of the magnetic film and magnetic anisotropy regulation; and a high-precision three-dimensional coil structure is integrated by combining microfabrication processes. The common-mode suppressor prepared thereby is small in volume and high in integration, exhibits excellent common-mode suppression performance, a wide working bandwidth, and excellent signal integrity in the high-frequency band, and at the same time has high reliability and is suitable for the new-generation HDMI interface.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic component preparation, and specifically to a preparation method of an HDMI common-mode suppressor made of nanocrystalline materials. Background Art

[0002] Some existing thin-film common-mode suppressors have improved their high-frequency performance to a certain extent and achieved device miniaturization through material and process improvements. However, to achieve a sufficiently high common-mode impedance, an extremely low differential-mode insertion loss, excellent signal integrity within the entire HDMI operating bandwidth, while also taking into account device miniaturization, low cost, and production consistency, the existing processes still have deficiencies. Especially in aspects such as optimizing the high-frequency magnetic properties of the magnetic core material, precisely integrating the magnetic core and the coil, and accurately controlling the multi-physical field coupling effect, the existing processes are difficult to fully meet the extreme performance requirements of the next-generation HDMI interface for common-mode suppressors. Therefore, developing a process preparation method to obtain an HDMI common-mode suppressor with higher performance, smaller size, and wider bandwidth has important practical significance and application value. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the present invention provides a preparation method of an HDMI common-mode suppressor made of nanocrystalline materials, which solves the problems of the existing technology.

[0004] Technical Solution

[0005] To achieve the above objectives, the present invention is used through the following technical solutions: A preparation method of an HDMI common-mode suppressor made of nanocrystalline materials, the preparation method includes the following steps:

[0006] Sp1. Microstructured pre-preparation of the substrate material:

[0007] Select or prepare a non-magnetic or weakly magnetic substrate material with a predetermined three-dimensional microstructure, and form a microgroove network for subsequent magnetic material filling and / or a microgroove network for guiding coil winding on the surface of the substrate material through laser direct writing, photolithography, or micro-nano imprinting technology; the substrate material can be selected from high-temperature ceramics, silicon-based materials, or high-temperature resistant polymers;

[0008] Sp2. Gradient sputtering and filling of multi-layer heterogeneous magnetic films:

[0009] Using a multi-target magnetron sputtering system, alternately or co-sputter an iron-based amorphous alloy layer (by default, the FeSiBNbCu system) and at least one functional regulation material layer in and on the groove network of the microstructured substrate; the functional regulation material layer is selected from:

[0010] Hexagonal ferrite nanoparticle layer or high-resistivity intermetallic compound layer (default Fe-Al-Si) for enhancing the magnetic permeability or reducing the loss in specific frequency bands (including >3 GHz);

[0011] Ultra-thin insulating dielectric layer (default AlN, SiO2 or Si3N4, thickness 5 - 50 nm) for enhancing interlayer insulation and stress isolation;

[0012] By precisely controlling the sputtering power, time and atmosphere of each target, a heterogeneous magnetic thin film structure with a composition gradient or multi-layer alternation is formed in the direction perpendicular to the substrate surface, and the total thickness matches the depth of the substrate trench;

[0013] Sp3, selective energy field-assisted nanocrystallization annealing:

[0014] Place the substrate assembly filled and covered with the heterogeneous magnetic thin film in a high vacuum or ultra-high purity inert atmosphere, and while applying an external static or dynamic magnetic field (0.1 - 2 T), use at least one of the following selective energy fields for assisted annealing to induce in-situ nanocrystallization of the magnetic thin film and optimize the magnetic anisotropy:

[0015] Femtosecond laser pulse irradiation annealing: Use a femtosecond laser with a specific wavelength and repetition frequency to perform a scanning rapid annealing on the magnetic thin film area to achieve precise control of the grain size and orientation in the local area;

[0016] Microwave plasma-assisted annealing: Use the microwave plasma energy field for uniform heating, and at the same time, the active particles in the plasma act on the film surface to regulate the grain boundary characteristics;

[0017] The peak annealing temperature is controlled between 450°C and 650°C, and the total annealing time is optimized according to the selected energy field type and film thickness to form a gradient or multiphase nanocrystalline / amorphous composite structure with a grain size in the range of 2 nm to 30 nm;

[0018] Sp4, micro-filling or self-assembly winding of integrated coils:

[0019] Using the micro-groove network prefabricated on the substrate or the micro-channels formed after filling with magnetic materials, form a common-mode choke coil by using at least one of the following methods:

[0020] Micro-filling and curing of metal paste: Fill a high-conductivity nano-metal paste (such as Ag, Cu nanoparticle paste) into the predetermined coil path by micro-injection or screen printing, and then form a wire by low-temperature sintering or photo-curing;

[0021] LIGA or electroforming process: Use photoresist to form a coil mold, and grow a high-precision copper coil in the mold by electrochemical deposition;

[0022] Two sets of coils with the same number of turns and symmetric distribution are formed to achieve low impedance passing of differential-mode signals and high impedance suppression of common-mode signals;

[0023] Sp5, Surface Passivation, Encapsulation and Characterization of Characteristics:

[0024] For the formed device, atomic layer deposition or plasma-enhanced chemical vapor deposition is carried out to form an ultra-thin and dense passivation protection layer (including Al2O3 or SiNx, with a thickness of 10 - 100 nm); subsequently, necessary pin leads and overall encapsulation are carried out;

[0025] Test its common-mode rejection ratio, differential-mode insertion loss, and group delay characteristics within the frequency range required by HDMI 2.1 and above standards (DC to 12 GHz or higher).

[0026] Preferably, in Sp1, for the design of the micro-groove network of the substrate material, the ratio of the depth to the width of the grooves (aspect ratio) is controlled between 3:1 and 15:1, and the groove walls have a surface roughness of less than 5 nm and are passivated to reduce interface defects during the deposition of the magnetic thin film; meanwhile, the micro-groove network is a three-dimensional topologically optimized columnar array or spiral guide rail, and its geometric parameters are optimized through finite element simulation, aiming to guide the coil to form a specific spatial configuration that minimizes high-frequency proximity effect and skin effect.

[0027] Preferably, in Sp2, through the programmed dynamic regulation of the sputtering rate of different target materials and the gas-phase reaction flow rate (oxygen or nitrogen partial pressure), a gradient interface layer with continuously changing composition and structure at the nanoscale is formed between the iron-based amorphous formed alloy layer and the functional regulation material layer, with a thickness of 5 nm to 20 nm. This gradient interface layer aims to eliminate the lattice mismatch stress between heterogeneous materials and achieve a smooth transition of physical parameters such as magnetic permeability, resistivity, or dielectric constant, so as to suppress the reflection and scattering of high-frequency signals at the interface.

[0028] Preferably, when using femtosecond laser pulse irradiation annealing in Sp3, combined with a spatial light modulator or digital micromirror device for pixel-level shaping and dynamic addressing of the laser beam, a mixed-phase structure of nanocrystalline regions with a preset pattern and amorphous retained regions, or nanocrystalline domains with different grain sizes / orientations is selectively induced to form within the magnetic thin film; the mixed-phase structure of the nanocrystalline regions with the preset pattern and amorphous retained regions, or nanocrystalline domains with different grain sizes / orientations is used to optimize the magnetic flux path in a specific HDMI frequency band or to construct an artificial electromagnetic bandgap structure in the magnetic core for notch absorption of common-mode noise at specific frequencies.

[0029] Preferably, the external magnetic field applied in Sp3 is a pulse composite magnetic field encoded by a time series, including a strong pulsed magnetic field (1T, pulse width <1 ms) in the same direction as a specific axial direction (including parallel to the expected current direction) in the plane of the thin film and a weak bias static magnetic field (<0.1T) orthogonal thereto. This specific sequence is designed to effectively break the isotropic growth of grains during the nanocrystallization process, induce the formation of uniaxial magnetic anisotropy with an extremely high squareness ratio and low coercivity, and the easy magnetization axis is parallel to the HDMI signal current path.

[0030] Preferably, when metal paste micro-filling and curing are used in Sp4, the metal paste is an anisotropic conductive adhesive containing core-shell structured nanosilver wires (the core is silver, the shell is ultra-thin graphene or conductive polymer, diameter <100 nm, length >10 µm), and the orientation arrangement of the nanosilver wires is realized by applying a weak electric field or magnetic field assistance during the filling process. After curing, a highly ordered conductive network arranged along the current path is formed, thereby significantly improving the current-carrying capacity and electromigration resistance of the wire at high frequencies while ensuring low resistivity.

[0031] Preferably, the integrated coil in Sp4 adopts a three-dimensional multi-layer staggered parallel winding structure, and the interlayer connection is realized through multi-layer vertical interconnection vias (VIA) prefabricated in the base material; the wire width and spacing of each layer of the coil are optimized according to the position of the layer in the overall structure and the current spectrum it undertakes. Specifically, the inner layer coil adopts a finer winding to capture higher-frequency common-mode components, and the outer layer adapts to lower frequencies, realizing distributed and multi-stage attenuation of HDMI broadband common-mode noise as a whole.

[0032] Preferably, the passivation protection layer formed in Sp5 is a composite film, and its main material is deposited by ALD or , and nanocapsules encapsulating low-melting-point alloys or repair agents are dispersed therein with a volume fraction of less than 1%; when microcracks occur in the device due to overheating or mechanical stress, the nanocapsules rupture and release the repair agent to achieve in-situ repair of the cracks, thereby improving the long-term reliability and environmental tolerance of the device, especially in the HDMI application scenarios of multiple pluggings and temperature cycles.

[0033] Preferably, before encapsulation in Sp5, a micro-magnetic field sensor array based on magnetic tunnel junctions or giant magnetoresistance effects is integrated at specific positions of the magnetic core (including the expected magnetic flux concentration area or high-stress area) through micro-nano processing technology. The sensor array is strongly magnetically coupled to the nanocrystalline magnetic material through an ultra-thin (<20 nm) medium layer with specific phonon transparency, used to monitor the dynamic changes in the internal magnetic flux density distribution of the common-mode suppressor in real time, and feedback this information for intelligent diagnosis or adaptive adjustment of HDMI system-level EMI.

[0034] The present invention provides a preparation method of an HDMI common-mode suppressor made of nanocrystalline materials. It has the following beneficial effects:

[0035] 1. Through the precise three-dimensional groove network design of the microstructured substrate and the optimization by finite element simulation, the present invention realizes the precise guidance of the magnetic flux path. The multi-target magnetron sputtering technology is used to prepare a multi-layer heterogeneous magnetic film, especially the combination of an iron-based amorphous alloy and a hexagonal ferrite or a high-resistivity intermetallic compound, and the nano-scale gradient interface layer ensures the smooth transition of physical parameters such as magnetic permeability and resistivity in the direction perpendicular to the substrate surface, effectively suppressing the reflection and scattering of high-frequency signals at the interface. Therefore, high magnetic permeability and low loss characteristics can be provided within a wide frequency band covering HDMI 2.1 standard and above, especially in the frequency band above 3 GHz.

[0036] 2. By selecting performance energy field-assisted nanocrystallization annealing, especially femtosecond laser combined with patterned annealing of a spatial light modulator or a digital micromirror device, and the application of a time-series encoded pulse composite magnetic field, the present invention can accurately control the size, orientation and magnetic anisotropy of nanocrystalline grains, realize the notch absorption of common-mode noise at specific frequencies, and further improve the high-frequency suppression depth and selectivity. The three-dimensional multi-layer interleaved parallel integrated coil, whose wire parameters are optimized according to the current spectrum borne by each layer, realizes the distributed and multi-stage attenuation of broadband common-mode noise and minimizes the high-frequency parasitic effect. Description of the Drawings

[0037] Figure 1 It is a process flow chart of the present invention. Detailed Embodiments

[0038] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention. Specific Embodiment 1:

[0040] As Figure 1 shown, a preparation method of an HDMI common-mode suppressor made of nanocrystalline materials includes the following steps:

[0041] Sp1. Microstructured preliminary preparation of the substrate material:

[0042] This step selects or prepares a non-magnetic or weakly magnetic substrate material with a predetermined three-dimensional microstructure. On the surface of this substrate material, a microgroove network for precise filling of subsequent magnetic materials and / or a microgroove network for guiding coil winding is formed through laser direct writing technology, photolithography technology, or micro-nano imprinting technology. Laser direct writing technology has high flexibility and is suitable for prototyping and small batch production; photolithography technology, as a mature microelectronic processing technology, has high precision and is suitable for large batch production; micro-nano imprinting technology, with its high cost-effectiveness, is suitable for large-area and high-throughput replication of microstructures, especially on polymer substrates. The substrate material is selected from alumina or aluminum nitride of high-temperature ceramics, high-resistance silicon of silicon-based materials, or polyimide of high-temperature-resistant polymers. These materials are all non-magnetic or weakly magnetic to avoid interfering with the performance of the magnetic core, and at the same time have good high-frequency dielectric properties, namely low loss tangent, excellent mechanical strength and thermal stability to withstand subsequent high-temperature processes, and are compatible with the selected micro-nano processing technology. The design of the grooves, including depth, width, shape, and spacing, is optimized through electromagnetic simulation software to achieve the best magnetic flux closure path, minimum leakage inductance, and parasitic capacitance. For silicon-based materials, a mature MEMS deep etching technology, namely deep reactive ion etching, is used to obtain grooves with a high aspect ratio; for ceramic materials, a laser ablation process is used, or a molding and punching process is combined with a green ceramic body; for high-temperature-resistant polymer substrates, a micro-nano imprinting or precision injection molding process is used.

[0043] In Sp1, the design of the microgroove network of the substrate material controls the ratio of the depth to the width of the grooves, that is, the aspect ratio, between 3:1 and 15:1. This high aspect ratio design allows more magnetic materials to be filled within a limited planar size, thereby effectively increasing the inductance and magnetic flux carrying capacity without significantly increasing the device volume, which is crucial for miniaturized high-performance chokes. And the groove walls have a surface roughness less than 5 nanometers and are passivated. The passivation treatment can be the formation of a thin SiO2 layer by thermal oxidation or the deposition of an insulating layer by ALD. This low roughness and smooth interface are beneficial for the uniform and dense filling of subsequent magnetic films and the formation of a high-quality interface, reducing the pinning centers of magnetic domain walls, reducing hysteresis loss, and the passivation treatment eliminates surface dangling bonds, improves interface stability, and reduces chemical reactions or diffusion between the magnetic material and the substrate. At the same time, the microgroove network presents the form of a three-dimensional topologically optimized columnar array or spiral guide rail, and its geometric parameters are optimized through finite element simulation, aiming to guide the coil to form a specific spatial configuration that minimizes the high-frequency proximity effect and skin effect; among them, the columnar array can be used to form a segmented magnetic core or precisely control the magnetic flux distribution, and the spiral guide rail provides physical guidance for the precise winding of the coil, ensuring a high degree of consistency in turn spacing and arrangement, which is decisive for achieving symmetric winding, reducing parasitic capacitance, and optimizing high-frequency current distribution.

[0044] Sp2, gradient sputtering and filling of multi-layer heterogeneous magnetic films:

[0045] A multi-target magnetron sputtering system is used to alternately or co-sputter an iron-based amorphous forming alloy layer, by default an FeSiBNbCu-based alloy, and at least one functional regulation material layer inside and on the surface of the trench network of the microstructured substrate. The FeSiBNbCu-based alloy forms nanocrystals after annealing, having a high saturation magnetic induction intensity and a high magnetic permeability in the medium and low frequency bands. The functional regulation material layer is selected from the following two categories: The first category is a hexagonal ferrite nanoparticle layer or a high-resistivity intermetallic compound layer, by default an Fe-Al-Si alloy, for enhancing the magnetic permeability or reducing the loss in a specific frequency band covering frequencies above 3 GHz; the hexagonal ferrite, including BaFe12O19 or Co2Z-type ferrite, has a very high cut-off frequency and anisotropy field, and can maintain good magnetic permeability and low loss in the frequency band above GHz, while the Fe-Al-Si alloy, i.e., Sendust alloy, has a high resistivity and can effectively suppress high-frequency eddy current loss. The second category is an ultra-thin insulating dielectric layer, by default AlN, SiO2 or Si3N4, for enhancing interlayer insulation and stress isolation, with its thickness precisely controlled between 5 nm and 50 nm. This layer provides electrical insulation between the magnetic layers, reduces interlayer eddy currents, and at the same time, the differences in its thermal expansion coefficient and mechanical properties are used to regulate the interlayer stress. This thickness ensures insulation without significantly diluting the overall magnetic properties. By precisely controlling the sputtering power, sputtering time and sputtering atmosphere of each target, including the argon pressure and the flow rate of reactive gases such as nitrogen or oxygen, a compositional gradient structure or a multi-layer alternating heterogeneous magnetic thin film structure is formed in the direction perpendicular to the substrate surface, and its total thickness precisely matches the trench depth of the substrate to ensure that the trenches are effectively filled and the expected magnetic core structure is formed. During the sputtering process, the substrate rotates and revolves to ensure the uniformity of the thin film, and the precise control of the substrate temperature also has a significant impact on the microstructure and stress of the thin film.

[0046] In Sp2, through the programmed dynamic regulation of the sputtering rates of different targets and the gas-phase reaction flow rates, i.e., the partial pressures of oxygen or nitrogen, a gradient interface layer with continuously changing composition and structure at the nanoscale is formed between the iron-based amorphous forming alloy layer and the functional regulation material layer, with a thickness of 5 nm to 20 nm. This gradient interface layer is formed by smoothly changing the sputtering rate of one material while smoothly increasing the sputtering rate of another material. Its core function is to eliminate the lattice mismatch stress between heterogeneous materials. Since different materials have different lattice parameters, direct contact will generate huge interface stress, affecting the thin film quality and even causing cracking. The gradient layer can buffer this mismatch; at the same time, it realizes the smooth transition of physical parameters such as magnetic permeability, resistivity or dielectric constant, avoiding the impedance mismatch of high-frequency signals at the interface caused by the sudden change of physical parameters, and thus the reflection and scattering losses, thereby improving the transmission characteristics of high-frequency signals and broadening the working bandwidth.

[0047] Sp3. Selective energy field-assisted nanocrystallization annealing:

[0048] Place the substrate assembly filled and covered with a heterogeneous magnetic film in a high vacuum or ultra-high purity inert atmosphere, which prevents the magnetic material from oxidizing at high temperatures. Apply an external static or dynamic magnetic field with an intensity range of 0.1 Tesla to 2 Tesla. At the same time, use at least one of the following selectable energy fields for assisted annealing to induce in-situ nanocrystallization of the magnetic film and optimize the magnetic anisotropy. The application of the external magnetic field, i.e., magnetic field annealing, induces magnetic anisotropy in the magnetic material, aligns the easy magnetization axis along a specific direction, and thus optimizes the shape of the hysteresis loop. The technical solutions of the selectable energy fields include:

[0049] Femtosecond laser pulse irradiation annealing: Use a femtosecond laser with a specific wavelength and repetition frequency to perform a scanning rapid annealing on the magnetic film area. The extremely short pulse width and extremely high peak power of the femtosecond laser enable ultrafast and non-equilibrium heating and cooling of the material, achieving precise control of the grain size and orientation in the local area, and even forming metastable phases or special microstructures that are difficult to obtain by conventional heat treatment.

[0050] Microwave plasma-assisted annealing: Use the microwave plasma energy field for uniform heating. At the same time, the high-energy active particles in the plasma, including ions and free radicals, act on the film surface to regulate the grain boundary characteristics. In addition, it can clean the surface, promote atomic diffusion, and reduce the crystallization temperature.

[0051] Precisely control the peak annealing temperature between 450°C and 650°C, and optimize the total annealing time according to the selected energy field type and film thickness. This process forms a gradient or multiphase nanocrystalline / amorphous composite structure with a grain size in the range of 2 nanometers to 30 nanometers. This gradient or multiphase structure, through precise control of the annealing conditions, especially the use of selectable energy fields, can form a composite structure with a gradient change in grain size from the surface to the inside or the coexistence of nanocrystalline phases and residual amorphous phases in the magnetic core, which is beneficial to meeting the magnetic property requirements at different frequencies.

[0052] When annealing is carried out by irradiating with femtosecond laser pulses in Sp3, the laser beam is pixel-level shaped and dynamically addressed by combining a spatial light modulator or a digital micromirror device. This technology enables the laser energy to be precisely projected onto specific tiny areas of the magnetic thin film according to a preset pattern, selectively inducing the formation of a nanocrystalline region with a preset pattern and an amorphous retention region, or a mixed-phase structure of nanocrystalline domains with different grain sizes / orientations within the magnetic thin film; among them, the amorphous region usually has a relatively high resistivity and is used to control the eddy current path, while nanocrystals with different sizes or orientations have different responses at different frequencies. The nanocrystalline region with a preset pattern and the amorphous retention region, or the mixed-phase structure of nanocrystalline domains with different grain sizes / orientations is used to optimize the magnetic flux path in a specific HDMI frequency band, or to construct an artificial electromagnetic bandgap structure in the magnetic core. This artificial electromagnetic bandgap structure, referring to the concept of photonic crystals or metamaterials, through periodic or quasi-periodic microstructural patterns, enables the material to exhibit a forbidden characteristic for the propagation of common-mode noise within a specific frequency range, for notch absorption or reflection of common-mode noise at a specific frequency, greatly enhancing the suppression performance of the target frequency band.

[0053] The external magnetic field applied in Sp3 is a pulse composite magnetic field encoded by a time series. This composite magnetic field includes a strong pulsed magnetic field in the same direction as a specific axial direction within the plane of the thin film, this axial direction being parallel to the expected current direction, with an intensity greater than 1 tesla and a pulse width less than 1 millisecond, and a weak bias static magnetic field orthogonal to it, with an intensity less than 0.1 tesla. The waveform, repetition frequency, duty cycle of this specific sequence of pulsed magnetic fields, and the application timing with respect to the static field are all carefully designed and programmed controlled, aiming to effectively break the isotropic growth of grains during the nanocrystallization process, overcome the limitation of traditional annealing that easily forms randomly oriented grains, induce the formation of uniaxial magnetic anisotropy with a very high squareness ratio and low coercivity, and the easy magnetization axis is precisely parallel to the HDMI signal current path. A high squareness ratio means rapid magnetization reversal, a low coercivity means small energy and low loss required for reversal, and the specific orientation of the easy magnetization axis is conducive to low-loss transmission of differential-mode signals, while presenting high impedance to common-mode currents perpendicular to this direction.

[0054] Sp4, microfilling or self-assembly winding of integrated coils:

[0055] Using the prefabricated microgroove network on the substrate or the microchannel formed after filling with magnetic materials as the precise forming path of the coil, a common-mode choke coil is formed by adopting at least one of the following methods. This integrated manufacturing method, that is, the coil is directly fabricated on or within the magnetic core structure, significantly improves the integration, precision, and consistency.

[0056] Specific forming methods include:

[0057] Metal paste micro-filling and curing: A highly conductive nano-metal paste, which is a mixture of silver or copper nano-particles, an organic carrier, and a binder, is precisely filled into a predetermined coil path through micro-injection techniques, such as precise control by an inkjet print head, or screen printing techniques, or doctor blade techniques. Then, through a low-temperature sintering process, such as thermal sintering, photon sintering, plasma sintering, or ultraviolet or thermal curing for specific conductive adhesives, a solid wire is formed. The low-temperature sintering technique is crucial for avoiding affecting the performance of the underlying nanocrystalline magnetic material.

[0058] LIGA or electroforming process: LIGA is a high aspect ratio micro-structure manufacturing technology. Here, the steps of lithography to form a mold and electroforming to fill the metal are mainly utilized. The electroforming process is to precisely grow a high-purity and high-density metal copper coil through an electrochemical deposition method in a coil-shaped mold formed by materials such as photoresist. This method can obtain very smooth sidewalls and precise geometries.

[0059] Finally, two sets of coils with the same number of turns and symmetric distribution are formed, achieving low impedance for differential mode signals due to magnetic flux cancellation, and high impedance suppression for common mode signals due to magnetic flux superposition. The lead-out and connection of the coil ends are key links that require precise processing, involving local insulation layer removal, micro-welding, or conductive adhesive connection.

[0060] When metal paste micro-filling and curing is adopted in Sp4.1a, the metal paste is an anisotropic conductive adhesive containing core-shell structured nano-silver wires. The core of the nano-silver wire is silver, providing high electrical conductivity. The shell is ultra-thin graphene or a conductive polymer. The graphene shell layer prevents the silver wires from oxidation and agglomeration, enhances the mechanical strength, and improves the interfacial contact with the matrix material. The conductive polymer shell layer also plays a similar role and endows the conductive adhesive with specific rheological properties. Its diameter is less than 100 nanometers and its length is greater than 10 micrometers, that is, a high aspect ratio, which is beneficial to forming an effective conductive network. And the orientation arrangement of the nano-silver wires is realized by applying a weak electric field or magnetic field assistance during the filling process. The electrical or magnetic properties of the nano-silver wires are utilized to induce their preferential arrangement along the field strength direction, that is, the desired current path. After curing, a highly ordered conductive network is formed along the current path. Compared with randomly distributed nano-particles, this ordered structure can provide a more direct and lower resistance conductive path, thus while ensuring a low resistivity, due to a better current distribution and reduced necking effect, significantly improving the current-carrying capacity and electromigration resistance of the wire at high frequencies.

[0061] The integrated coil in Sp4 adopts a three-dimensional multi-layer interleaved parallel winding structure. The coils are stacked in multiple layers vertically, and electrical connections between different layers are achieved through multiple prefabricated vertical vias (VIA) in the substrate material. The fabrication of VIA itself is part of microfabrication. Interleaving means that there is a certain offset in the spatial position of the coil windings between adjacent layers, which is used to optimize magnetic field coupling or reduce inter-layer parasitic capacitance. The wire width and spacing of each layer of the coil are optimized according to the position of this layer in the overall structure and the current spectrum it undertakes: the inner-layer coils adopt a denser winding, which can be understood as thinner wires or more turns, aiming to capture and suppress higher-frequency common-mode components; the outer layer adapts to lower frequencies and can use wider wires or different numbers of turns to optimize the suppression of lower-frequency common-mode noise. Overall, it realizes the distributed and multi-stage attenuation of HDMI broadband common-mode noise, that is, common-mode noise of different frequencies is attenuated specifically by specific optimized structures in different layers or regions of the device.

[0062] Sp5, Surface Passivation, Packaging and Characterization:

[0063] Atomic layer deposition (ALD) or plasma-enhanced chemical vapor deposition (PECVD) is carried out on the formed device to form an ultra-thin and dense passivation protection layer. The material of this protection layer is alumina (Al2O3) or silicon nitride (SiNx), and the thickness is controlled within 10 nanometers to 100 nanometers. The ALD technology can control the film thickness and composition with atomic layer precision and has excellent conformality; the PECVD technology has a relatively fast deposition rate and can be carried out at a lower temperature. The passivation layer protects the internal sensitive magnetic materials and coil structures from environmental factors such as moisture, oxygen, and chemical corrosion, improves the long-term stability and reliability of the device, and provides necessary electrical insulation at the same time. Subsequently, necessary lead-out of pins and overall packaging are carried out. The packaging materials adopt epoxy molding, ceramic packaging or metal shielding enclosures, providing mechanical protection, electromagnetic shielding (if the packaging material is conductive) and standardized external dimensions. The selection of the packaging method needs to comprehensively consider factors such as cost, heat dissipation requirements, electromagnetic shielding requirements, and the integration method with the PCB board. The parasitic parameters introduced by packaging in high-frequency applications also need to be strictly controlled.

[0064] Finally, its common-mode rejection ratio, differential-mode insertion loss, and group delay characteristics are tested within the frequency range required by HDMI 2.1 and above standards, which covers DC to 12 GHz or higher. The characterization is carried out using a vector network analyzer in cooperation with a special test fixture for S-parameter measurement, and then the above key parameters are extracted from it.

[0065] The passivation protection layer formed in Sp5 is a composite film. Its main material is Al2O3 or HfO2 deposited by ALD. Both alumina and hafnium oxide are dielectric materials and barrier layer materials with excellent performance, having high density, good chemical stability and electrical insulation. And a low melting point alloy, such as Sn-Bi alloy system, or a repair agent, such as nano-capsules of polymerizable monomers, is dispersed and encapsulated in it with a volume fraction less than 1%. When micro-cracks are generated in the device due to overheating or mechanical stress, the micro-cracks expand and cause the nearby nano-capsules to rupture. If the temperature of the device rises above the melting point of the low melting point alloy encapsulated in the capsule, it will melt and flow into the cracks, and solidify after cooling to repair the cracks; or the liquid repair agent flows into the cracks and fills them by capillary action, and then reacts with the moisture in the air or polymerizes and cures under specific conditions, thus filling the cracks, achieving in-situ repair of the cracks, preventing the further expansion of the cracks, and restoring the protection function of the passivation layer. This design significantly improves the long-term reliability of the device and its tolerance in harsh environments.

[0066] Before encapsulation in Sp5, at specific positions of the magnetic core, namely the expected magnetic flux concentration area or high stress area, a micro magnetic field sensor array based on the magneto tunneling junction (MTJ) or giant magnetoresistance (GMR) effect is integrated through micro-nano processing technology. Both MTJ and GMR sensors are very sensitive to magnetic field changes and are easy to be miniaturized and integrated. The sensor array and the nanocrystalline magnetic material are strongly magnetically coupled through an ultra-thin dielectric layer with a thickness less than 20 nanometers and specific phonon transparency, such as high-quality Si3N4 or AlN, to form a dense passivation protection layer. This coupling design ensures that the sensor can accurately sense the magnetic field state inside the magnetic core while maintaining electrical insulation, and the phonon transparency means that heat can be effectively conducted. This integration is used to monitor the dynamic changes of the magnetic flux density distribution inside the common mode suppressor in real time, and feedback this information for intelligent diagnosis or adaptive adjustment of HDMI system-level EMI, providing a basis for building an intelligent or adaptive EMI protection system.

[0067] The multi-scale heterostructure design breaks through the limitations of single nanocrystalline materials. Through gradient or multi-layer composites, it aims to achieve a wider frequency band and more excellent frequency response characteristics. Introducing the idea of semiconductor micro-nano processing into the preparation of magnetic cores provides new possibilities for subsequent coil integration and magnetic flux path control. Unconventional annealing means such as femtosecond laser or microwave plasma aim to achieve more precise regulation of the nanocrystalline structure (grain size, orientation, grain boundary), obtaining properties that cannot be achieved by traditional heat treatment. Abandoning traditional manual or machine winding and adopting high-precision processes such as micro-filling and LIGA can greatly reduce parasitic parameters, improve integration and consistency. The functionalized passivation layer endows the passivation layer with additional functions, and the integrated sensor provides data for future intelligent HDMI systems.

[0068] It should be noted that in this text, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising a reference structure" does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0069] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method of an HDMI common-mode suppressor made of nanocrystalline materials, characterized in that: The preparation method includes the following: Sp1. Micro-structured pre-preparation of the substrate material: Select or prepare a non-magnetic or weakly magnetic substrate material with a predetermined three-dimensional microstructure, and form a micro-groove network for subsequent filling of magnetic materials on the surface of the substrate material; Sp2. Gradient sputtering and filling of multi-layer heterogeneous magnetic films: Alternately or co-sputter an iron-based amorphous alloy layer and a functional regulation material layer in the groove network and on the surface of the substrate material. The functional regulation material layer is selected from one or a combination of more of Fe-Al-Si, AlN, SiO2 or Si3N4; By controlling the sputtering power, time and atmosphere of each target, a heterogeneous magnetic film with a composition gradient or multi-layer alternating structure is formed in the direction perpendicular to the substrate surface, and the total thickness matches the depth of the substrate groove; Sp3. Selective performance energy field-assisted nanocrystallization annealing: Place the substrate assembly filled and covered with the heterogeneous magnetic film in a high vacuum or ultra-high purity inert atmosphere, and while applying an external static or dynamic magnetic field, use an energy field to assist annealing to induce in-situ nanocrystallization of the magnetic film and optimize the magnetic anisotropy; Anneal to form a gradient or multi-phase nanocrystalline / amorphous composite structure with a grain size in the range of 2 nm to 30 nm; Sp4. Micro-filling or self-assembly winding of integrated coils: Utilize the micro-groove network prefabricated on the substrate or the micro-channels formed after filling with magnetic materials, and form a common-mode choke coil by using at least one of the following methods: Sp4.1a. Fill a highly conductive nano-metal paste into a predetermined coil path by micro-injection or screen printing, and then form a wire by low-temperature sintering or photocuring; Sp4.1b. Use a photoresist to form a coil mold, and grow a copper coil in the mold by electrochemcial deposition method; Sp5. Surface passivation, encapsulation and property characterization: Perform atomic layer deposition or plasma enhanced chemical vapor deposition on the formed device to form an ultra-thin and dense passivation protection layer; Subsequently, lead out pins and perform overall encapsulation.

2. The preparation method of an HDMI common-mode suppressor made of a nanocrystalline material according to claim 1, characterized in that, In the design of the micro-groove network of the substrate material in Sp1, the ratio of the depth to the width of the groove is controlled between 3:1 and 15:1, and the groove wall has a surface roughness of less than 5 nm and is passivated; The micro-groove network is a three-dimensional topologically optimized columnar array or spiral guide rail.

3. The preparation method of an HDMI common-mode suppressor made of a nanocrystalline material according to claim 1, characterized in that, In Sp2, by programmatically dynamically regulating the sputtering rates of different targets and the gas-phase reaction flow rates, a gradient interface layer with continuous gradual changes in composition and structure at the nanoscale is formed between the iron-based amorphous alloy layer and the functional regulation material layer, with a thickness of 5 nm to 20 nm.

4. The preparation method of an HDMI common-mode suppressor made of nanocrystalline materials according to claim 1, characterized in that, The method of using an energy field for assisted annealing in Sp3 is to use femtosecond laser pulses for irradiation annealing, and at the same time, combine a spatial light modulator or a digital micromirror device to shape and dynamically address the laser beam, selectively inducing the formation of nanocrystalline regions with a preset pattern and amorphous retention regions, or a mixed-phase structure of nanocrystalline domains with different grain sizes / orientations within the magnetic thin film; the nanocrystalline regions with the preset pattern and the amorphous retention regions, or the mixed-phase structure of nanocrystalline domains with different grain sizes / orientations are used to optimize the magnetic flux path in a specific HDMI frequency band or construct an artificial electromagnetic bandgap structure in the magnetic core to notch and absorb specific frequency common-mode noise.

5. The preparation method of an HDMI common mode suppressor made of nanocrystalline material according to claim 1, characterized in that, The external magnetic field applied in Sp3 is a pulse composite magnetic field encoded by a time series, including a strong pulsed magnetic field in the same direction as a specific axial direction in the plane of the thin film and a weak bias static magnetic field orthogonal to it.

6. The preparation method of an HDMI common mode suppressor made of a nanocrystalline material according to claim 1, characterized in that, When using metal paste micro-filling and curing in Sp4.1a, the metal paste is an anisotropic conductive adhesive containing core-shell structured nanosilver wires, and the orientation arrangement of the nanosilver wires is realized by applying a weak electric field or magnetic field assistance during the filling process, and an ordered conductive network is formed along the current path after curing.

7. The preparation method of an HDMI common mode suppressor made of nanocrystalline materials according to claim 1, characterized in that, The integrated coil in Sp4 adopts a three-dimensional multi-layer interleaved parallel winding structure, and the interlayer connection is realized through multi-layer vertical through vias prefabricated in the substrate material.

8. The preparation method of an HDMI common-mode suppressor made of a nanocrystalline material according to claim 1, characterized in that, The passivation protection layer formed in the Sp5 is a composite film, and its main material is deposited by ALD or , and nanocapsules encapsulating a low melting point alloy or a repair agent are dispersed therein with a volume fraction of less than 1%; when microcracks are generated in the device due to overheating or mechanical stress, the nanocapsules rupture to release the repair agent, realizing in-situ repair of the cracks.

9. The preparation method of an HDMI common-mode suppressor made of nanocrystalline materials according to claim 1, characterized in that, Before encapsulation in Sp5, a micro magnetic field sensor array is integrated based on the expected magnetic flux concentration area or high stress area of the magnetic core. The micro magnetic field sensor array and the nanocrystalline magnetic material are strongly magnetically coupled through an ultra-thin dielectric layer, and are used to monitor the dynamic changes in the internal magnetic flux density distribution of the common mode suppressor in real time.

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