Miniaturized chip inductor structure electronic component with electromagnetic interference resistance

Abstract

This invention provides a miniaturized chip inductor structure electronic component with electromagnetic interference suppression, comprising: a multilayer composite magnetic core, coaxially stacked from soft magnetic materials of different permeabilities, with a through-hole at the center for a coil to pass through; a helical coil, made of conductive metal wire with low parasitic parameters, tightly wound within the through-hole of the multilayer composite magnetic core, with both ends extending axially to the outside of the multilayer composite magnetic core; a fully enclosed shielding layer, made of a high-permeability metal material, tightly covering the multilayer composite magnetic core and the helical coil; end electrodes, symmetrically disposed at both ends of the shielding layer; and an insulating protective layer, completely coated on the outer surface of the shielding layer. This invention optimizes magnetic circuit closure, reduces high-frequency losses, and suppresses electromagnetic interference, while effectively suppressing electromagnetic interference, ensuring high-frequency operating performance, and improving component reliability and stability within a sub-millimeter miniaturized size.

Description

Technical Field

[0001] This invention relates to the field of electronic components technology, and in particular to a miniaturized chip inductor structure electronic component that is resistant to electromagnetic interference. Background Technology

[0002] As a fundamental passive component in surface mount technology (SMT), chip inductors are widely used in power filtering, radio frequency matching, and electromagnetic compatibility (EMC) circuits of communication terminals, IoT nodes, wearable devices, and high-density integrated circuits. With the rapid development of 5G / 6G communication, high-speed digital circuits, and miniaturized electronic devices, system operating frequencies are continuously increasing (generally entering the range of hundreds of MHz to several GHz), placing higher demands on component dimensions (such as 01005 packages, 0.4 mm × 0.2 mm), electromagnetic interference (EMI) immunity, and high-frequency electrical performance. Against this backdrop, chip inductors need to achieve low electromagnetic leakage, high self-resonant frequency (SRF), high Q value, and stable inductance within an extremely small volume to ensure system signal integrity and reliability. Currently, the mainstream chip inductor structures in the industry mainly include wire-wound, multilayer laminated, and thin-film types. Wire-wound inductors, formed by winding a magnetic core with wires and then encapsulating it, offer high inductance and Q-value. However, their three-dimensional open magnetic circuit structure causes the alternating magnetic field to easily radiate outwards during operation, potentially leading to crosstalk between adjacent circuits in high-density PCB layouts. Furthermore, the physical winding process is insufficient for sub-millimeter miniaturization requirements. Multilayer laminated inductors, employing an alternating layering and sintering process of magnetic ceramic paste and internal electrodes, offer a compact structure suitable for automated production. However, the planar helical coils inherently possess large parasitic parameters, exhibiting significant skin and proximity effects at high frequencies, resulting in rapid Q-value decay. Insufficient magnetic circuit closure also limits shielding effectiveness; further reductions in the number of coil turns during miniaturization lead to decreased inductance and saturation current. Thin-film inductors, fabricated using photolithography and sputtering processes, offer high coil precision and excellent high-frequency characteristics. However, they suffer from low inductance, high DC resistance, high cost, and difficulty handling large operating currents, limiting their application range. To improve EMI immunity, existing technologies attempt to introduce external metal shielding (such as conductive resin coatings or permalloy shells) or embed magnetic shielding layers within the laminated structure. However, while external shielding can partially suppress electromagnetic radiation, it significantly increases the overall height and volume of the component, contradicting the trend towards miniaturization. Simultaneously, the parasitic capacitance formed between the shielding layer and the coil reduces the self-resonant frequency (SRF), deteriorating high-frequency performance. Internal shielding solutions face reliability issues such as high process complexity, mismatched thermal expansion coefficients at multiple material interfaces, and susceptibility to microcracks during sintering. Furthermore, the shielding layer occupies limited internal space, compressing the effective magnetic circuit volume and leading to deterioration of inductance parameters. Moreover, under sub-millimeter size constraints, process tolerances are extremely small; even minute structural deviations can cause magnetic circuit asymmetry, making the shielding effect unstable and even exacerbating local eddy current losses and temperature rise, further affecting long-term operational reliability. In summary, existing chip inductor technology presents an irreconcilable contradiction between miniaturization and electromagnetic interference suppression: size reduction exacerbates the risk of electromagnetic leakage, while traditional shielding methods introduce new problems such as increased volume, deteriorated high-frequency characteristics, increased process complexity, and decreased reliability.This technological bottleneck has severely restricted the stable operation of high-density, high-frequency electronic systems in complex electromagnetic environments, and has become a key technical problem that urgently needs to be solved in this field. Summary of the Invention

[0003] The purpose of this application is to provide a miniaturized chip inductor structure electronic component that resists electromagnetic interference, which has the advantages of effectively suppressing electromagnetic interference, ensuring high-frequency operating performance, and improving component reliability and stability at a sub-millimeter miniaturized size.

[0004] A miniaturized chip inductor structure electronic component with electromagnetic interference suppression, comprising: The multilayer composite magnetic core is composed of at least two layers of soft magnetic materials with different permeabilities stacked coaxially. A through hole is opened in the center for the coil to pass through, which is used to optimize the magnetic circuit closure and reduce high-frequency eddy current loss, and to meet the sub-millimeter miniaturization requirements. The spiral coil is made of conductive metal wire with low parasitic parameters tightly wound in the through hole of the multilayer composite magnetic core. Its two ends extend along the magnetic core axis to the outside of the multilayer composite magnetic core to reduce the influence of high frequency skin effect and proximity effect, and ensure high Q value and stable inductance. The fully enclosed shielding layer, made of high-permeability metal material, is tightly wrapped around the multilayer composite magnetic core and the spiral coil to form a closed magnetic circuit to suppress alternating magnetic field leakage, resist external electromagnetic interference, and avoid significantly increasing the component size. The end electrodes are symmetrically located at both ends of the shielding layer and are electrically connected to the two ends of the spiral coil extending to the outside of the magnetic core. They are compatible with surface mount technology (SMT) to ensure soldering reliability and current conduction stability. An insulating protective layer is completely coated on the outer surface of the shielding layer to achieve external insulation, moisture and corrosion protection, while avoiding parasitic interference between the shielding layer and surrounding circuits, thus improving the long-term reliability of the components.

[0005] Furthermore, this application proposes that a multilayer composite magnetic core is composed of an inner layer of high-permeability soft magnetic material and an outer layer of low-permeability soft magnetic material, which are coaxially stacked. The inner layer of high-permeability soft magnetic material is a nanocrystalline alloy, and the outer layer of low-permeability soft magnetic material is ferrite. An insulating isolation layer is provided between the two to solve the problems of high high-frequency loss and insufficient magnetic circuit closure of a single magnetic core material.

[0006] Furthermore, this application proposes that the insulating layer is made of polyimide material with a thickness between 0.01 and 0.03 mm, and is tightly bonded to both the inner high-permeability soft magnetic material and the outer low-permeability soft magnetic material, in order to avoid the risk of mismatch in the thermal expansion coefficients of the multi-material interface and prevent the generation of microcracks.

[0007] Furthermore, this application also proposes that the spiral coil is made of flat copper wire with a diameter between 0.05-0.2mm, the number of coil turns is 5-20, the spacing between adjacent coils is between 0.02-0.1mm, and it is wound in the through hole of a multi-layer composite magnetic core to ensure stable inductance in a very small volume, while reducing high-frequency skin effect loss.

[0008] Furthermore, this application proposes that the shielding layer material is permalloy or iron-nickel alloy, with a thickness between 0.03-0.1 mm, and is uniformly coated on the outside of the multilayer composite magnetic core and the spiral coil by vacuum sputtering process. An air gap is reserved between its inner wall and the outer wall of the multilayer composite magnetic core to reduce the negative impact of parasitic capacitance on the self-resonant frequency (SRF) while ensuring shielding effectiveness.

[0009] Furthermore, this application also proposes that the air gap width be between 0.01 and 0.05 mm, which is used to precisely adjust the inductance value and quality factor Q value of the components, and ensure performance stability in high-frequency operating scenarios.

[0010] Furthermore, this application also proposes that the terminal electrodes are made of silver-palladium alloy material and formed on both ends of the shielding layer by electroplating process, with a thickness between 0.02-0.05mm. An anti-oxidation coating is provided on the outer surface, which is a titanium nitride or tungsten carbide coating, to adapt to high-density PCB layout and improve soldering reliability and long-term working stability.

[0011] Furthermore, this application also proposes that the overall package size of the component is 01005 package (0.4mm×0.2mm) or less, and the overall height does not exceed 0.2mm, which meets the sub-millimeter miniaturization requirements and is compatible with micro electronic devices such as wearable devices and IoT nodes.

[0012] Furthermore, this application also proposes that the inner wall of the through hole of the multilayer composite magnetic core is provided with a polyimide insulating coating with a thickness between 0.01-0.03mm, which is used to achieve reliable insulation isolation between the helical coil and the multilayer composite magnetic core, and avoid leakage risk and local eddy current loss at high frequency.

[0013] Furthermore, this application also proposes that the insulating protective layer is made of epoxy resin material, formed on the outer surface of the shielding layer by dip coating process, with a thickness between 0.01-0.03mm, and has flame retardant and anti-aging properties, with a flame retardant rating of UL94V-0, to improve the long-term working reliability of the component in complex electromagnetic environment. The total thickness of the multilayer composite magnetic core is between 0.1 and 0.3 mm, of which the inner layer of high permeability soft magnetic material accounts for 60-80% of the total thickness. This is used to ensure sufficient magnetic flux under miniaturization constraints, while balancing high-frequency loss and inductance stability. The length of the end of the spiral coil extending to the outside of the multilayer composite magnetic core is between 0.1 and 0.3 mm. This end is electrically connected to the end electrode by brazing with a tin-silver-copper alloy to ensure conduction stability and welding reliability in high-frequency and high-current scenarios.

[0014] As can be seen from the above, the miniaturized chip inductor structure electronic component with electromagnetic interference suppression provided in this application optimizes the magnetic circuit closure, reduces high-frequency loss, and suppresses electromagnetic interference through structures including multi-layer composite magnetic cores, spiral coils, and fully enclosed shielding layers. At the same time, it is adapted to the sub-millimeter miniaturization requirements and has the advantages of effectively suppressing electromagnetic interference, ensuring high-frequency operating performance, and improving component reliability and stability at a sub-millimeter miniaturized size.

[0015] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram showing the structure of the present invention.

[0018] Figure label: 1. Multilayer composite magnetic core; 101. Through hole; 2. Spiral coil; 3. Fully enclosed shielding layer; 4. End electrode. Detailed Implementation

[0019] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0020] It is important to note that terms such as "first," "second," "symmetric," and "array" are used only to distinguish between descriptive and positional descriptions and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, features specified with terms such as "first" or "symmetric" may explicitly or implicitly include one or more of that feature; similarly, when the quantity of certain features is not limited by words such as "two" or "three," it should be noted that such features also explicitly or implicitly include one or more features. The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] like Figure 1-2 As shown in the figure, this invention provides a miniaturized chip inductor structure electronic component with electromagnetic interference resistance, as proposed in this application. The component includes a multilayer composite magnetic core, a helical coil, a fully enclosed shielding layer, terminal electrodes, and an insulating protective layer. The multilayer composite magnetic core is composed of at least two layers of soft magnetic materials with different permeabilities coaxially stacked, with a through-hole at the center for the coil to pass through, optimizing magnetic circuit closure, reducing high-frequency eddy current losses, and adapting to sub-millimeter miniaturization requirements. The helical coil is made of low parasitic parameter conductive metal wire tightly wound within the through-hole of the multilayer composite magnetic core, with both ends extending axially along the core to the outside of the multilayer composite magnetic core, reducing the effects of high-frequency skin effect and proximity effect, ensuring high Q value and stable inductance. The fully enclosed shielding layer is made of a high-permeability metal material and tightly covers the multilayer composite magnetic core and the helical coil, forming a closed magnetic circuit to suppress alternating magnetic field leakage, resist external electromagnetic interference, and avoid significantly increasing the component size. The end electrodes are symmetrically located at both ends of the shielding layer, corresponding one-to-one with the two ends of the spiral coil extending to the outside of the magnetic core, adapting to surface mount technology (SMT) to ensure soldering reliability and current conduction stability. An insulating protective layer is completely coated on the outer surface of the shielding layer to achieve external insulation, moisture and corrosion protection, while avoiding parasitic interference between the shielding layer and surrounding circuits, improving the long-term operational reliability of the component.

[0022] The miniaturized chip inductor structure electronic component for electromagnetic interference suppression proposed in this application optimizes the magnetic circuit and reduces high-frequency eddy current losses through a multi-layer composite magnetic core, reduces high-frequency skin and proximity effects through a spiral coil, suppresses electromagnetic leakage and resists external interference through a fully enclosed shielding layer, and ensures connection reliability and environmental adaptability through terminal electrodes and insulating protective layers. Thus, this component, with a sub-millimeter miniaturization size, effectively solves the problems of electromagnetic leakage, high-frequency characteristic degradation, increased size, and decreased reliability in existing technologies, ensuring the stable operation of high-density, high-frequency electronic systems in complex electromagnetic environments.

[0023] The inner high-permeability soft magnetic material is preferably a nanocrystalline alloy, the outer low-permeability soft magnetic material is preferably a ferrite, and an insulating layer is provided between the two.

[0024] Specifically, the multilayer composite magnetic core employs a coaxial stacked structure of an inner layer of high-permeability soft magnetic material and an outer layer of low-permeability soft magnetic material. This design aims to fully utilize the advantages of different magnetic materials to optimize overall magnetic performance. The inner layer of high-permeability soft magnetic material is primarily responsible for providing high permeability within a miniaturized size, ensuring sufficient inductance for the inductor. This inner layer of high-permeability soft magnetic material can be a nanocrystalline alloy. Due to its unique microstructure, nanocrystalline alloys possess extremely high initial permeability and saturation magnetic induction, while effectively reducing eddy current losses at high frequencies, making them ideal as the core magnetic material for inductors. Besides nanocrystalline alloys, high-permeability soft magnetic materials can also be permalloy, amorphous alloys, etc. The outer layer of low-permeability soft magnetic material is mainly used to improve high-frequency characteristics and suppress high-frequency eddy current losses. This outer layer of low-permeability soft magnetic material can be ferrite. Ferrite materials exhibit relatively low losses and high resistivity at high frequencies, which helps to further suppress high-frequency eddy currents. As the outer layer, ferrite works synergistically with the inner layer of high-permeability soft magnetic material to balance the overall high-frequency loss characteristics and provide some mechanical support. Besides ferrite, the low-permeability soft magnetic material can also be certain types of amorphous alloys or composite magnetic materials. An insulating layer is placed between the inner high-permeability soft magnetic material and the outer low-permeability soft magnetic material. The main function of this insulating layer is to provide reliable electrical insulation, preventing additional eddy current paths from being generated between different magnetic materials due to direct contact, thereby reducing high-frequency loss. Simultaneously, this insulating layer can effectively alleviate interfacial stress that may be caused by differences in the thermal expansion coefficients of different materials, enhance the mechanical stability of the structure, and prevent microcracks or delamination under temperature changes or long-term operation. In addition to polyimide materials, the insulating layer can also be made of inorganic insulating films such as alumina, silicon nitride, and silicon dioxide, or organic polymer films such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), and can be achieved through various processes such as physical vapor deposition (PVD), chemical vapor deposition (CVD), spin coating, or lamination.

[0025] Through the above technical solution, the multilayer composite magnetic core is designed as an inner layer of high-permeability nanocrystalline alloy and an outer layer of low-permeability ferrite, coaxially stacked and supplemented with an insulating layer. This application can effectively solve the problems of high eddy current loss and insufficient magnetic circuit closure of single magnetic core materials at high frequencies. The nanocrystalline alloy, as the inner layer, provides high permeability, ensuring sufficient inductance even at miniaturized sizes; while the outer ferrite layer effectively suppresses high-frequency eddy current loss, improving the quality factor Q of the component at high frequencies. The insulating layer further optimizes the electrical isolation and mechanical stability of the interfaces between different magnetic materials, avoiding parasitic losses and structural failures. This composite structure enables the inductor to maintain sub-millimeter-level miniaturization while significantly improving its performance stability, efficiency, and reliability in high-frequency applications, making it particularly suitable for microelectronic devices with stringent high-frequency performance requirements.

[0026] In this regard, this application further proposes that the above-mentioned insulating isolation layer is made of polyimide material with a thickness between 0.01-0.03 mm, and is closely bonded to both the inner high permeability soft magnetic material and the outer low permeability soft magnetic material, in order to avoid the risk of mismatch of thermal expansion coefficients at the multi-material interface and prevent the generation of microcracks.

[0027] The thickness of the insulating layer is precisely controlled within the range of 0.01 mm to 0.03 mm. This thickness range is chosen to ensure that the insulating layer provides sufficient electrical insulation and thermal stress buffering capabilities while minimizing its impact on the overall size of miniaturized components and optimizing the thermal stress distribution at the interface, avoiding the negative effects of being too thick or too thin. This thickness can be achieved by precisely controlling process parameters such as coating amount, lamination pressure, or film thickness.

[0028] By employing polyimide as the insulating layer and precisely controlling its thickness and adhesion, the excellent heat resistance and low coefficient of thermal expansion of polyimide can be effectively utilized to form a flexible and stable buffer layer between the inner high-permeability soft magnetic material and the outer low-permeability soft magnetic material. This buffer layer can effectively absorb and disperse the thermal stress caused by the mismatch of the thermal expansion coefficients of different materials, thereby significantly avoiding the risk of microcracks at the multi-material interface. This not only ensures the structural integrity and long-term reliability of the multilayer composite magnetic core, but also ensures the stable output of the magnetic and electrical properties of the inductor under wide temperature ranges and high-frequency operating conditions, avoiding performance drift or failure caused by structural damage, and thus improving the service life and reliability of miniaturized chip inductor electronic components in complex environments.

[0029] In some of the above embodiments, a spiral coil with low parasitic parameters is proposed, which is tightly wound within a through-hole of a multilayer composite magnetic core to ensure a high Q value and stable inductance. However, in extremely miniaturized chip inductor structures, how to further optimize the coil structure within a limited space to ensure that losses caused by high-frequency skin effect and proximity effect are effectively suppressed while maintaining a stable inductance is a key challenge in achieving high-performance miniaturized inductors.

[0030] In response, this application further proposes that the spiral coil is made of flat copper wire with a diameter between 0.05-0.2mm, the number of coil turns is 5-20 turns, the spacing between adjacent coils is between 0.02-0.1mm, and it is wound in the through hole of a multi-layer composite magnetic core to ensure stable inductance in a very small volume, while reducing high-frequency skin effect loss.

[0031] The diameter of the flat copper wire is between 0.05 and 0.2 mm. Here, "diameter" typically refers to the smaller cross-sectional dimension of the flat copper wire, i.e., its thickness. This thickness range is chosen to balance the mechanical strength, winding feasibility, and current carrying capacity of the wire within a miniaturized footprint. Wires that are too thin may result in insufficient mechanical strength and excessive resistance, while wires that are too thick will increase the coil volume, hindering miniaturization. This size range ensures that the coil provides sufficient conductive cross-section within a very small space to reduce DC resistance and high-frequency losses.

[0032] The coil has 5-20 turns. The number of turns is a key parameter determining the inductance. With a given core and coil size, increasing the number of turns increases the inductance, but also increases the coil's DC resistance and parasitic capacitance, thus affecting the quality factor (Q) and self-resonant frequency (SRF). The 5-20 turn range is optimized to balance inductance requirements with high-frequency performance in miniaturized inductors, ensuring the desired inductance value is achieved within a limited volume.

[0033] The spacing between adjacent coils is between 0.02 and 0.1 mm. The spacing between adjacent coils has a significant impact on the parasitic capacitance, proximity effect, and heat dissipation performance of the coils. A smaller spacing helps increase inductance density but may increase inter-turn capacitance and proximity effect losses; a larger spacing may reduce inductance density but is beneficial for reducing parasitic effects and improving heat dissipation. The 0.02-0.1 mm spacing range aims to optimize these factors, effectively controlling parasitic capacitance and proximity effect while ensuring inductance and Q value, to adapt to high-frequency operating environments.

[0034] The helical coil is wound within a through-hole of a multilayer composite magnetic core. This feature emphasizes the tight bonding between the coil and the core. Winding within the through-hole of the multilayer composite magnetic core allows magnetic flux to be efficiently concentrated inside the core, forming a closed magnetic circuit, thereby improving inductance efficiency. Combined with flat copper wire, a specific number of turns, and spacing, this winding method ensures high inductance density and excellent magnetic coupling within a very small through-hole space, while further optimizing magnetic performance by utilizing the properties of the core material.

[0035] In this regard, this application further proposes that the shielding layer material is permalloy or iron-nickel alloy, with a thickness between 0.03-0.1 mm, and is uniformly coated on the outside of the multilayer composite magnetic core and the spiral coil by vacuum sputtering process. An air gap is reserved between its inner wall and the outer wall of the multilayer composite magnetic core to reduce the negative impact of parasitic capacitance on the self-resonant frequency (SRF) while ensuring shielding effectiveness.

[0036] This application further proposes that the air gap width be between 0.01 and 0.05 mm to precisely adjust the inductance and Q-factor of the component, ensuring performance stability in high-frequency operating scenarios. The width of this air gap is a key parameter for achieving high-performance inductors. When the air gap width is too small (e.g., less than 0.01 mm), the distance between the shielding layer and the multilayer composite core is too short, resulting in insignificant reduction in parasitic capacitance. Furthermore, during manufacturing, extremely small gaps are difficult to control precisely, easily leading to short circuits or decreased manufacturing yield. Conversely, if the air gap width is too large (e.g., greater than 0.05 mm), although parasitic capacitance can be further reduced, it significantly increases the overall size of the component, contradicting the miniaturization design goal, and may weaken magnetic coupling efficiency, affecting the stability of the inductance value. Therefore, precisely controlling the air gap width between 0.01 mm and 0.05 mm can effectively balance the suppression of parasitic capacitance, magnetic coupling efficiency, component size, and manufacturing feasibility. This precise gap width can be achieved in several ways. For example, before vacuum sputtering the shielding layer, a sacrificial layer or insulating dielectric layer of controllable thickness can be pre-coated on the outer wall of the multilayer composite magnetic core, and the sacrificial layer can be removed after the shielding layer is formed. Alternatively, the precise distance between the shielding layer and the magnetic core can be ensured through precision molds and assembly processes.

[0037] By precisely limiting the air gap width between the shielding layer and the multilayer composite magnetic core to between 0.01mm and 0.05mm using the above technical solution, accurate adjustment of the inductance and quality factor (Q) of the component can be achieved. Specifically, this precise air gap, acting as a low-dielectric-constant medium, effectively reduces the parasitic capacitance formed between the shielding layer and the internal spiral coil and multilayer composite magnetic core. The reduction in parasitic capacitance significantly increases the inductor's self-resonant frequency (SRF), thereby maintaining a higher Q value and reducing energy loss under high-frequency operating conditions. Simultaneously, the precisely controlled air gap width also optimizes the magnetic circuit structure, ensuring stable and predictable inductance within the design range. This precise parameter control ensures stable and reliable inductance performance in high-frequency applications, such as wearable devices and IoT nodes, preventing system failures caused by parameter drift or excessive high-frequency losses, and greatly improving the long-term reliability and overall performance stability of the component.

[0038] In some embodiments described above in this application, terminal electrodes are proposed for adapting to surface mount technology (SMT) to ensure soldering reliability and current conduction stability. However, with the increasing prevalence of miniaturized electronic components and the increasingly complex working environment, traditional terminal electrodes may face problems such as oxidation and corrosion during long-term use, thereby affecting their compatibility with high-density PCBs and the long-term operational reliability of the overall components.

[0039] This application further proposes a specific implementation method for the end electrodes. The end electrodes are made of a silver-palladium alloy material, chosen for its excellent conductivity, oxidation resistance, and corrosion resistance, which effectively reduces contact resistance and enhances the chemical stability of the electrode. Specifically, the ratio of the silver-palladium alloy can be optimized according to actual needs; for example, the silver content can be set between 70% and 90%, and the palladium content between 10% and 30%, to achieve a balance between conductivity, mechanical strength, and cost. The end electrodes are formed at both ends of the fully enclosed shielding layer through an electroplating process. The electroplating process ensures a strong and highly conductive metallurgical bond between the end electrodes and the shielding layer, while achieving precise control over electrode size and surface quality. During the electroplating process, the surface of the shielding layer needs to be pretreated, such as cleaned and activated, and the composition, temperature, current density, and electroplating time of the electroplating solution must be strictly controlled to obtain a uniform and dense silver-palladium alloy layer. The thickness of the terminal electrode is between 0.02-0.05 mm. This thickness range is carefully designed to ensure sufficient mechanical strength and excellent conductivity while meeting the stringent dimensional requirements of miniaturized components. It avoids insufficient strength or excessive resistance due to excessive thinness, or increased component size due to excessive thickness. To further enhance the protective capability of the terminal electrode, an anti-oxidation coating is applied to its outer surface. This coating effectively isolates the terminal electrode from contact with the external environment, especially under harsh working conditions such as high temperature, high humidity, or corrosive gases, thereby significantly extending the service life of the terminal electrode. The anti-oxidation coating is either titanium nitride or tungsten carbide. Both titanium nitride and tungsten carbide are hard ceramic materials with high hardness, excellent wear resistance, corrosion resistance, and good conductivity. Titanium nitride coatings can be prepared using physical vapor deposition (PVD) techniques such as reactive magnetron sputtering or ion plating, while tungsten carbide coatings can be prepared using methods such as chemical vapor deposition (CVD) or plasma spraying. These coatings can form a dense protective layer, effectively preventing oxidation and corrosion of the end electrode surface. At the same time, their high hardness also improves the wear resistance of the end electrode, which is beneficial to the reliability of the surface mount process.

[0040] In some embodiments described above in this application, a miniaturized chip inductor structure electronic component comprising a multilayer composite magnetic core and a helical coil is proposed. However, when the helical coil is tightly wound within the through-hole of the multilayer composite magnetic core, if there is insufficient insulation between the coil and the magnetic core, leakage current may occur under high-frequency operating conditions, and local eddy current losses may be induced, thereby affecting the performance stability and long-term reliability of the component.

[0041] In response, this application further proposes the aforementioned miniaturized chip inductor structure electronic component for electromagnetic interference resistance, wherein the inner wall of the through hole of the multilayer composite magnetic core is provided with a polyimide insulating coating, the thickness of which is between 0.01-0.03mm, to achieve reliable insulation isolation between the helical coil and the multilayer composite magnetic core, thereby avoiding leakage risk and local eddy current loss at high frequencies.

[0042] The above technical solution involves applying a polyimide insulating coating to the inner wall of the through-hole in the multilayer composite magnetic core. This coating, with its excellent dielectric properties and precise thickness, creates a reliable electrical insulation barrier between the spiral coil and the multilayer composite magnetic core. This effectively blocks potential current leakage paths during high-frequency operation, significantly reducing the risk of leakage. Simultaneously, this insulating layer suppresses localized eddy currents generated within the magnetic core due to coil induction, reducing unnecessary energy loss and heat accumulation. This meticulous insulation treatment not only ensures the electrical performance stability and high Q value of the miniaturized chip inductor in high-frequency environments but also improves the long-term operational reliability of the component, preventing performance degradation or damage due to insulation failure. This is particularly crucial for sub-millimeter-level miniaturized inductors, where the balance between space utilization and performance stability is paramount.

[0043] To address this, this application further proposes a miniaturized chip inductor structure electronic component with electromagnetic interference resistance. The structure and connection method of its insulating protective layer, multilayer composite magnetic core, and helical coil are optimized to solve the challenges still faced in practical applications, such as long-term operational reliability, conduction stability under high-frequency, high-current scenarios, and balancing high-frequency losses and inductance stability under miniaturization constraints. For example, a typical insulating protective layer may not effectively cope with flame retardancy and aging issues in complex electromagnetic environments; if the size and material ratio of the magnetic core are not precisely controlled, it is difficult to simultaneously meet the requirements of miniaturization, high magnetic flux, and low loss; and the connection method between the coil and the terminal electrodes may also affect the stable transmission of high-frequency signals and the durability of soldering.

[0044] The insulating protective layer of this application is made of epoxy resin material, formed on the outer surface of the shielding layer through a dip-coating process, with a thickness between 0.01-0.03 mm. It possesses flame-retardant and anti-aging properties, achieving a UL94V-0 flame-retardant rating, and is used to improve the long-term operational reliability of the component in complex electromagnetic environments. Specifically, the insulating protective layer uses epoxy resin material, which has excellent electrical insulation properties, good mechanical strength, and chemical stability, effectively protecting the internal structure from external environmental corrosion. The dip-coating process ensures that the epoxy resin material uniformly and completely covers the outer surface of the shielding layer, forming a dense protective layer. Its thickness is controlled between 0.01-0.03 mm, providing sufficient insulation and protection while minimizing the increase in the overall size of the component. Furthermore, this epoxy resin material also possesses flame-retardant and anti-aging properties, achieving a UL94V-0 flame-retardant rating. This means that under extreme conditions, the component can effectively suppress flame spread and resist material performance degradation during long-term use, thereby significantly improving the long-term operational reliability of the component in complex electromagnetic environments.

[0045] The following example will provide a more detailed explanation of the above technical solution: In the design of miniaturized electronic devices (e.g., for wearable devices or IoT nodes), a tiny chip inductor (e.g., a 01005 package, i.e., 0.4mm × 0.2mm, with an overall height not exceeding 0.2mm) is required to perform power filtering and RF matching functions. This inductor needs to maintain stable inductance, high quality factor (Q value), and effectively suppress electromagnetic interference (EMI) at operating frequencies ranging from hundreds of MHz to several GHz, while avoiding significant electromagnetic leakage to ensure signal integrity in high-density circuit board (PCB) layouts. Traditional wire-wound inductors are prone to electromagnetic radiation due to their open magnetic circuit structure and are difficult to meet sub-millimeter miniaturization requirements; multilayer chip inductors have large parasitic parameters and rapid Q value decay at high frequencies, and limited shielding effectiveness; while external shielding increases component size and introduces parasitic capacitance, reducing the self-resonant frequency (SRF).

[0046] To address the aforementioned challenges, this technical solution provides a miniaturized chip inductor structure electronic component with electromagnetic interference resistance. The core of this component is a **multilayer composite magnetic core**. This core is coaxially stacked from an inner layer of high-permeability soft magnetic material and an outer layer of low-permeability soft magnetic material; for example, the inner layer may be a nanocrystalline alloy, and the outer layer may be ferrite. An insulating layer of polyimide with a thickness between 0.01-0.03 mm is placed between the two layers. This insulating layer is tightly bonded, effectively avoiding the risk of thermal expansion coefficient mismatch between different materials and preventing microcrack formation. This composite structure solves the problems of high loss and insufficient magnetic circuit closure at high frequencies associated with single-core materials. Simultaneously, within the constraints of miniaturization (e.g., a total thickness between 0.1-0.3 mm, with the inner high-permeability soft magnetic material accounting for 60-80% of the total thickness), it ensures sufficient magnetic flux and balances high-frequency loss with inductance stability. The magnetic core has a through hole at its center, and its inner wall has a polyimide **insulating coating** with a thickness of 0.01-0.03mm, which is used to achieve reliable insulation between the subsequently wound helical coil and the magnetic core, avoiding leakage risks and local eddy current losses at high frequencies.

[0047] A **helical coil** is densely wound within the through-hole of the multilayer composite magnetic core. This coil is wound with flat copper wire, for example, with a diameter between 0.05-0.2 mm, 5-20 turns, and a spacing between adjacent coils between 0.02-0.1 mm. This flat copper wire design effectively reduces the effects of high-frequency skin and proximity effects, ensuring a high Q value and stable inductance, while achieving stable inductance within a very small volume. The two ends of the helical coil extend axially along the core to the outside of the multilayer composite magnetic core, with an end length between 0.1-0.3 mm.

[0048] To further enhance electromagnetic interference resistance and suppress electromagnetic leakage, a **fully enclosed shielding layer** is tightly wrapped around the multilayer composite magnetic core and helical coil. This shielding layer is made of a high-permeability metallic material, such as permalloy or iron-nickel alloy, with a thickness between 0.03-0.1 mm, and is uniformly formed using a vacuum sputtering process. Unlike traditional external shielding covers, this shielding layer has a **0.01-0.05 mm wide air gap** between it and the outer wall of the multilayer composite magnetic core. This air gap, while ensuring shielding effectiveness, effectively reduces the negative impact of parasitic capacitance formed between the shielding layer and the coil on the self-resonant frequency (SRF), and can be used to precisely adjust the inductance and quality factor (Q) of the components, ensuring performance stability in high-frequency operating scenarios. This fully enclosed structure forms a closed magnetic circuit, effectively suppressing alternating magnetic field leakage, resisting external electromagnetic interference, and avoiding a significant increase in component size.

[0049] **End electrodes** are symmetrically positioned at both ends of the shielding layer. These end electrodes are made of a silver-palladium alloy, formed by electroplating, with a thickness between 0.02-0.05 mm. An anti-oxidation coating, such as titanium nitride or tungsten carbide, is applied to the outer surface of the end electrodes to adapt to high-density PCB layouts and improve soldering reliability and long-term operational stability. The two ends of the helical coil extending outside the magnetic core are electrically connected to these end electrodes via tin-silver-copper alloy brazing, ensuring conduction stability and soldering reliability under high-frequency, high-current conditions, and adapting to surface mount technology (SMT).

[0050] Finally, an **insulating protective layer** is completely coated on the outer surface of the shielding layer. This protective layer is made of epoxy resin and formed by a dip-coating process, with a thickness between 0.01 and 0.03 mm. This insulating protective layer has flame-retardant and anti-aging properties; for example, its flame-retardant rating reaches UL94V-0. It is used to achieve external insulation, moisture protection, and corrosion resistance, while avoiding parasitic interference between the shielding layer and surrounding circuits, and improving the long-term operational reliability of components in complex electromagnetic environments.

[0051] Through the synergistic effect of the aforementioned technical features, this miniaturized chip inductor structure electronic component achieves excellent electromagnetic interference (EMI) immunity, high Q value, stable inductance, and high self-resonant frequency within the constraints of a 01005 package and smaller. For example, in a miniature wireless communication module, this inductor is used as an RF matching element. Its fully enclosed shielding layer effectively suppresses the inductor's own magnetic field leakage, avoiding crosstalk to nearby high-sensitivity RF circuits. Meanwhile, its internal air gap design ensures high SRF, avoiding performance degradation caused by parasitic capacitance in traditional shielding schemes. Simultaneously, the design of the multilayer composite magnetic core and flat copper wire spiral coil maintains low loss and stable inductance at high frequencies, meeting the stringent requirements of high-frequency performance and miniaturization. This overall solution overcomes the inherent contradiction between miniaturization and EMI immunity in existing technologies, providing a solution for the stable operation of high-density, high-frequency electronic systems in complex electromagnetic environments.

[0052] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A miniaturized chip inductor structure electronic component against electromagnetic interference, characterized in that, include: The multilayer composite magnetic core is composed of at least two layers of soft magnetic materials with different permeabilities stacked coaxially. A through hole is opened in the center for the coil to pass through, which is used to optimize the magnetic circuit closure and reduce high-frequency eddy current loss, and to meet the sub-millimeter miniaturization requirements. The spiral coil is made of conductive metal wire with low parasitic parameters tightly wound in the through hole of the multilayer composite magnetic core. Its two ends extend along the magnetic core axis to the outside of the multilayer composite magnetic core to reduce the influence of high frequency skin effect and proximity effect, and ensure high Q value and stable inductance. The fully enclosed shielding layer, made of a high-permeability metal material, tightly wraps around the multilayer composite magnetic core and the spiral coil to form a closed magnetic circuit to suppress alternating magnetic field leakage, resist external electromagnetic interference, and avoid significantly increasing the component size. The end electrodes are symmetrically arranged at both ends of the shielding layer and are electrically connected to the two ends of the spiral coil extending to the outside of the magnetic core, which are compatible with surface mount technology (SMT) to ensure soldering reliability and current conduction stability. An insulating protective layer is completely coated on the outer surface of the shielding layer to achieve external insulation, moisture and corrosion protection, while avoiding parasitic interference between the shielding layer and surrounding circuits, and improving the long-term reliability of the components.

2. The miniaturized chip inductor structure electronic component with electromagnetic interference suppression as described in claim 1, characterized in that, The multilayer composite magnetic core is composed of an inner layer of high-permeability soft magnetic material and an outer layer of low-permeability soft magnetic material, which are coaxially stacked. The inner layer of high-permeability soft magnetic material is a nanocrystalline alloy, and the outer layer of low-permeability soft magnetic material is ferrite. An insulating isolation layer is provided between the two to solve the problems of high high-frequency loss and insufficient magnetic circuit closure of a single magnetic core material.

3. The miniaturized chip inductor structure electronic component with electromagnetic interference suppression as described in claim 1, characterized in that, The insulating layer is made of polyimide material with a thickness between 0.01 and 0.03 mm. It is tightly bonded to both the inner high-permeability soft magnetic material and the outer low-permeability soft magnetic material to avoid the risk of mismatch in the thermal expansion coefficients of the multi-material interface and prevent the generation of microcracks.

4. The miniaturized chip inductor structure electronic component with electromagnetic interference suppression as described in claim 1, characterized in that, The spiral coil is made of flat copper wire with a diameter between 0.05-0.2mm. The number of coil turns is 5-20, and the spacing between adjacent coils is between 0.02-0.1mm. It is wound in the through hole of a multi-layer composite magnetic core to ensure stable inductance in a very small volume, while reducing high-frequency skin effect loss.

5. The miniaturized chip inductor structure electronic component with electromagnetic interference suppression as described in claim 1, characterized in that, The shielding layer material is permalloy or iron-nickel alloy, with a thickness between 0.03-0.1 mm. It is uniformly coated on the outside of the multilayer composite magnetic core and the spiral coil by vacuum sputtering. An air gap is reserved between its inner wall and the outer wall of the multilayer composite magnetic core to reduce the negative impact of parasitic capacitance on the self-resonant frequency (SRF) while ensuring shielding effectiveness.

6. The miniaturized chip inductor structure electronic component with electromagnetic interference suppression as described in claim 1, characterized in that, The air gap width is between 0.01 and 0.05 mm, which is used to precisely adjust the inductance value and quality factor Q value of the components to ensure performance stability in high-frequency operating scenarios.

7. The miniaturized chip inductor structure electronic component with electromagnetic interference suppression as described in claim 1, characterized in that, The terminal electrodes are made of silver-palladium alloy and are formed on both ends of the shielding layer by electroplating. The thickness is between 0.02-0.05mm. An anti-oxidation coating is provided on the outer surface. The anti-oxidation coating is titanium nitride or tungsten carbide coating, which is used to adapt to high-density PCB layout and improve soldering reliability and long-term working stability.

8. The miniaturized chip inductor structure electronic component with electromagnetic interference suppression as described in claim 1, characterized in that, The overall package size of the component is 01005 (0.4mm×0.2mm) or smaller, and the overall height does not exceed 0.2mm, meeting the sub-millimeter miniaturization requirements and adapting to micro electronic devices such as wearable devices and IoT nodes.

9. The miniaturized chip inductor structure electronic component with electromagnetic interference suppression as described in claim 1, characterized in that, The inner wall of the through hole of the multilayer composite magnetic core is provided with a polyimide insulating coating with a thickness between 0.01-0.03mm, which is used to achieve reliable insulation isolation between the spiral coil and the multilayer composite magnetic core, and avoid leakage risk and local eddy current loss at high frequency.

10. The miniaturized chip inductor structure electronic component with electromagnetic interference suppression as described in claim 1, characterized in that, The insulating protective layer is made of epoxy resin material and is formed on the outer surface of the shielding layer by dip coating process. The thickness is between 0.01-0.03mm. It has flame retardant and anti-aging properties, and the flame retardant rating reaches UL94V-0 level, which is used to improve the long-term working reliability of the component in complex electromagnetic environment. The total thickness of the multilayer composite magnetic core is between 0.1 and 0.3 mm, of which the thickness of the inner layer of high permeability soft magnetic material accounts for 60-80% of the total thickness. This is used to ensure sufficient magnetic flux under miniaturization constraints, while balancing high-frequency loss and inductance stability. The length of the end of the spiral coil extending to the outside of the multilayer composite magnetic core is between 0.1 and 0.3 mm. This end is electrically connected to the end electrode by brazing with a tin-silver-copper alloy to ensure conduction stability and welding reliability in high-frequency and high-current scenarios.

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