Nanocrystalline magnetic core, preparation method thereof and electronic device

Abstract

The invention relates to the technical field of magnetic element packaging, in particular to a nanocrystalline magnetic core, a preparation method thereof and an electronic device. According to the nanocrystalline magnetic core, the protective shell wraps the outer surface of the nanocrystalline bare magnetic core to form a protective structure. The interface gap between the nanocrystalline bare magnetic core and the protective shell is smaller than or equal to 0.1 mm, so that the protective shell and the nanocrystalline bare magnetic core are tightly attached, relative displacement caused by vibration or impact is eliminated, uniformity of interface contact is improved, stress concentration is reduced, and mechanical stability is improved. Moreover, a small interface gap is formed between the nanocrystalline bare magnetic core and the protective shell, so that the risk of partial discharge caused by an air gap is eliminated, the electrical reliability under the high-frequency and high-voltage working condition is guaranteed, and the electrical safety is improved. The nanocrystalline bare magnetic core is tightly attached to the protective shell, so that permeation paths of pollutants such as moisture and dust are blocked, the long-term stability of the nanocrystalline magnetic core in a humid and hot environment is improved, and the environmental adaptability is optimized.

Description

Technical Field

[0001] This application relates to the field of magnetic component packaging technology, and in particular to the design of a nanocrystalline magnetic core and its preparation method, as well as electronic devices. Background Technology

[0002] Nanocrystalline magnetic cores are widely used in electronic components such as high-frequency transformers and inductors due to their excellent magnetic properties. A protective shell is installed on the outside of the nanocrystalline magnetic core to protect it from mechanical damage and environmental influences.

[0003] In related technologies, a single-sided gap of 0.3mm to 1.5mm is generally reserved between the protective shell and the magnetic core to ensure the convenience of assembly between the magnetic core and the protective shell.

[0004] However, the gap between the casing and the magnetic core not only affects the overall compactness of the structure, but also the relative movement between the magnetic core and the casing may lead to problems such as vibration noise, partial discharge, and moisture intrusion during long-term use, thereby reducing the reliability of the device. Summary of the Invention

[0005] This application provides a nanocrystalline magnetic core and its preparation method, as well as an electronic device, to reduce the gap between the casing and the magnetic core.

[0006] To achieve the above objectives, this application adopts the following technical solution:

[0007] The first aspect of this application provides a nanocrystalline magnetic core, comprising: a bare nanocrystalline magnetic core and a protective shell, wherein the protective shell covers the outside of the bare nanocrystalline magnetic core, and the interface gap between the bare nanocrystalline magnetic core and the protective shell is less than or equal to 0.1 mm.

[0008] Compared with the prior art, the nanocrystalline magnetic core provided in this application has the following advantages:

[0009] In this embodiment of the application, the nanocrystalline magnetic core has a protective shell covering the outer surface of the bare nanocrystalline magnetic core, forming a protective structure to prevent the bare nanocrystalline magnetic core from being subjected to mechanical damage and environmental influences.

[0010] The interfacial gap between the nanocrystalline bare magnetic core and the sheath is less than or equal to 0.1 mm, which ensures a tight fit between the sheath and the nanocrystalline bare magnetic core, eliminating relative displacement caused by vibration or impact, improving the uniformity of interfacial contact, reducing stress concentration, and enhancing mechanical stability.

[0011] Moreover, the smaller interface gap between the nanocrystalline bare magnetic core and the casing eliminates the risk of partial discharge caused by air gaps, ensuring electrical reliability under high-frequency and high-voltage conditions and improving electrical safety.

[0012] The tight fit between the nanocrystalline bare magnetic core and the protective shell blocks the penetration path of pollutants such as moisture and dust, improves the long-term stability of the nanocrystalline magnetic core in humid and hot environments, and optimizes environmental adaptability.

[0013] As an improvement to the nanocrystalline magnetic core described in this application, the protective shell is applied to the outside of the bare nanocrystalline magnetic core by thermoplastic molding, injection molding, heat shrink molding, or potting molding.

[0014] As an improvement to the nanocrystalline magnetic core described in this application, the protective shell is made of a thermoplastic material, and the coefficient of thermal expansion of the protective shell is 1×10⁻⁶. -5 / ℃~1×10 -4 / ℃.

[0015] As an improvement to the nanocrystalline magnetic core described in this application, the protective shell is made of a thermo-shrinkable material.

[0016] As an improvement to the nanocrystalline magnetic core described in this application, the thermal shrinkage rate of the protective shell is 20% to 50%.

[0017] As an improvement to the nanocrystalline magnetic core described in this application, the temperature resistance of the protective shell is greater than or equal to 120°C.

[0018] A second aspect of this application provides a method for preparing a nanocrystalline magnetic core, comprising:

[0019] Provide an initial protective shell and fit the initial protective shell over the outside of the nanocrystalline bare magnetic core;

[0020] The initial protective shell is heated to shrink and cover the outside of the nanocrystalline bare magnetic core, forming the nanocrystalline magnetic core; wherein the interface gap between the nanocrystalline bare magnetic core and the protective shell is less than or equal to 0.1 mm.

[0021] Compared with existing technologies, the method for preparing nanocrystalline magnetic cores provided in this application has the following advantages:

[0022] In this embodiment, after the initial protective shell is fitted onto the outside of the nanocrystalline bare magnetic core, it is heated, causing the initial protective shell to shrink and cover the outside of the nanocrystalline bare magnetic core, forming the nanocrystalline magnetic core. The heating method allows the initial protective shell to thermally shrink and adhere to the outside of the nanocrystalline bare magnetic core, which is not only simple to operate and low in cost, facilitating mass production, but also helps ensure a close fit between the protective shell and the nanocrystalline bare magnetic core, contributing to achieving zero gap.

[0023] The protective shell serves to protect the bare nanocrystalline magnetic core, preventing it from mechanical damage and environmental impact. Furthermore, the interface gap between the bare nanocrystalline magnetic core and the protective shell is less than or equal to 0.1 mm, ensuring a tight fit between them and structurally eliminating the mechanical displacement problems caused by pre-existing gaps in the protective shell in existing technologies.

[0024] Moreover, under vibration or shock conditions, the tight fit between the casing and the nanocrystalline bare magnetic core effectively suppresses relative displacement caused by gaps, thereby reducing resonance noise and the risk of structural loosening, ensuring the long-term stability of the nanocrystalline bare magnetic core in complex environments. Furthermore, the tight fit blocks the intrusion paths of moisture and impurities, reducing the possibility of partial discharge and improving electrical safety.

[0025] As an improvement to the preparation method described above in this application, the thickness of the initial protective shell is greater than or equal to 0.5 mm and less than or equal to 2 mm.

[0026] As an improvement to the preparation method described above in this application, the single-sided gap between the initial protective shell and the nanocrystalline bare magnetic core is 0.3 mm to 1.5 mm.

[0027] As an improvement to the preparation method described above in this application, the heating of the initial protective shell includes:

[0028] The protective shell is heated using a segmented heating method.

[0029] As an improvement to the preparation method described above in this application, the preparation method further includes:

[0030] After the initial protective shell is fitted over the outside of the nanocrystalline bare magnetic core, it is placed in the mold cavity;

[0031] After heating the initial protective shell, the initial protective shell and the nanocrystalline bare magnetic core are extruded using a mold cavity to form the nanocrystalline magnetic core.

[0032] As an improvement to the preparation method described above in this application, the material of the protective shell is a heat-shrinkable material, and the heat shrinkage rate of the protective shell is 20% to 50%.

[0033] As an improvement to the preparation method described above in this application, the temperature resistance of the protective shell is greater than or equal to 120°C.

[0034] A third aspect of this application also provides an electronic device comprising the nanocrystalline magnetic core described in the first aspect, or a nanocrystalline magnetic core prepared by the method described in the second aspect.

[0035] The electronic device provided in the third aspect of this application, since it includes the nanocrystalline magnetic core of the first aspect or the nanocrystalline magnetic core prepared by the preparation method of the second aspect, also has the same advantages as the first or second aspect. Attached Figure Description

[0036] 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 of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are only a part of the embodiments of this application. These drawings and text descriptions are not intended to limit the scope of the concept of this application in any way, but to illustrate the concept of this application to those skilled in the art by referring to specific embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 A cross-sectional schematic diagram of the nanocrystalline magnetic core provided in the embodiments of this application;

[0038] Figure 2 A physical diagram of the nanocrystalline magnetic core provided in the embodiments of this application;

[0039] Figure 3 for Figure 2 Flaw morphology image of medium-nanocrystalline magnetic core. Detailed Implementation

[0040] Nanocrystalline magnetic cores are widely used in high-frequency electronic devices such as communication base stations, new energy inverters, industrial motor drives, and smart meters due to their excellent high-frequency magnetic properties and low-loss characteristics.

[0041] Magnetic components such as high-frequency transformers and inductors need to withstand the effects of high-frequency alternating magnetic fields, mechanical vibrations, and complex environments (such as temperature fluctuations and moisture corrosion) for extended periods. To protect the magnetic core from mechanical damage and environmental interference, a protective casing is usually designed on its exterior.

[0042] In existing technologies, a 0.3mm to 1.5mm single-sided gap is reserved between the casing and the magnetic core to ensure ease of assembly. However, this gap not only increases the device size but may also cause relative displacement between the magnetic core and the casing, leading to problems such as vibration noise, partial discharge, and moisture penetration, ultimately reducing the reliability of the device.

[0043] For example, in the high-frequency power module of a communication base station, the presence of a gap between the magnetic core and the casing may generate noise due to high-frequency vibration, interfering with signal transmission; as another example, in a new energy inverter, moisture in the gap may cause insulation degradation, leading to short-circuit faults.

[0044] In addition, the complexity of the casing process in existing technologies (such as filling material coating and multi-step assembly) increases production costs and makes it difficult to meet the requirements of large-scale production with high reliability and high consistency.

[0045] Therefore, there is an urgent need for a packaging structure and process that can achieve zero-gap bonding between the protective shell and the nanocrystalline magnetic core to solve core problems such as poor mechanical stability, low electrical safety, and insufficient structural compactness, thereby improving the overall performance and lifespan of magnetic components.

[0046] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0047] This application provides a nanocrystalline magnetic core to solve the problem of a large gap between the casing and the core in related technologies, thereby improving product reliability and structural stability.

[0048] Reference Figure 1 The nanocrystalline magnetic core provided in this application embodiment includes a nanocrystalline bare magnetic core 10 and a protective shell 20. The protective shell 20 covers the outside of the nanocrystalline bare magnetic core 10, and the interface gap between the nanocrystalline bare magnetic core 10 and the protective shell 20 is less than or equal to 0.1 mm.

[0049] Among them, the nanocrystalline bare magnetic core 10 is a magnetic element made of nanocrystalline material, which has high-frequency magnetic properties and low loss characteristics, and is used in electronic devices such as high-frequency transformers and inductors.

[0050] The nanocrystalline bare magnetic core 10 can be ring-shaped, square, etc., and the shape of the nanocrystalline bare magnetic core 10 is not limited in the embodiments of this application.

[0051] The protective shell 20 covers the outside of the nanocrystalline bare magnetic core 10, serving to protect the nanocrystalline bare magnetic core 10. The protective shell 20 can be made of polymer materials, such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), polyolefin, etc.

[0052] In this embodiment of the application, the interface gap refers to the gap between the nanocrystalline bare magnetic core 10 and the protective shell 20.

[0053] It is understood that in the embodiments of this application, the interface gap between the nanocrystalline bare magnetic core 10 and the sheath 20 is less than or equal to 0.1 mm, which means that the maximum gap between the nanocrystalline bare magnetic core 10 and the sheath 20 is less than or equal to 0.1 mm.

[0054] In actual processing, the gaps between the outer surface of the nanocrystalline bare magnetic core 10 and the sheath 20 are not uniform. For example, some surfaces of the nanocrystalline bare magnetic core 10 are in close contact with the sheath 20, which can be understood as having no gap between the nanocrystalline bare magnetic core 10 and the sheath 20; while some protrusions of the sheath 20 result in gaps between the nanocrystalline bare magnetic core 10 and the sheath 20.

[0055] In this embodiment, the shape of the protective shell 20 matches the outer contour shape of the nanocrystalline bare magnetic core 10. After the protective shell 20 is wrapped around the outside of the nanocrystalline bare magnetic core 10 through the process, zero-gap bonding is achieved.

[0056] Zero gap can be understood as the interface gap between the nanocrystalline bare magnetic core 10 and the protective shell 20 being less than or equal to 0.1 mm.

[0057] With the above-mentioned device, the nanocrystalline bare magnetic core 10 of this application embodiment is provided with a protective shell 20, which serves to protect the nanocrystalline bare magnetic core 10 and prevent the nanocrystalline bare magnetic core 10 from being subjected to mechanical damage and environmental influence.

[0058] Furthermore, the interface gap between the nanocrystalline bare magnetic core 10 and the protective shell 20 is less than or equal to 0.1 mm, which makes the protective shell 20 fit tightly with the nanocrystalline bare magnetic core 10, thus eliminating the mechanical displacement problem caused by the reserved gap in the protective shell 20 in the prior art.

[0059] Moreover, under vibration or shock conditions, the tight fit between the protective shell 20 and the nanocrystalline bare magnetic core 10 effectively suppresses relative displacement caused by gaps, thereby reducing resonance noise and the risk of structural loosening, and ensuring the long-term stability of the nanocrystalline bare magnetic core 10 in complex environments. In addition, the tight fit blocks the intrusion path of moisture and impurities, reduces the possibility of partial discharge, and improves electrical safety.

[0060] In some embodiments of this application, the protective shell is wrapped around the outside of the nanocrystalline bare magnetic core by thermoplastic molding, injection molding, heat shrink molding or potting molding.

[0061] In some examples, the protective shell is placed over the bare nanocrystalline magnetic core and then heated to cause thermoplastic deformation, tightly adhering to the surface of the bare nanocrystalline magnetic core, forming a nanocrystalline magnetic core with no visible gaps, thus creating a mechanically self-locking structure. This method requires minimal modification to processing equipment and facilitates rapid, small-batch production.

[0062] In other examples, a bare nanocrystalline magnetic core is placed and fixed in a mold cavity; then, molten injection molding material is injected into the cavity, covering the outside of the bare nanocrystalline magnetic core; after cooling and demolding, a protective shell is formed that adheres to the outside of the bare nanocrystalline magnetic core, achieving zero-gap encapsulation. This method is suitable for mass automated production and allows for the integration of other functional structures onto the nanocrystalline magnetic core.

[0063] Among them, the injection molding material can be a low viscosity, high flowability and excellent insulation performance engineering plastic, such as PBT or PPS (Polyphenylene Sulfide).

[0064] The injection molding material needs to have good electrical insulation, temperature resistance and mechanical strength, and glass fiber, flame retardant, UV protection components, etc. can be added as needed.

[0065] In other examples, the outer casing of the bare nanocrystalline magnetic core is heated, causing it to shrink and fit tightly against the surface of the core. This method achieves a zero-gap fit between the casing and the core, improving the compactness and vibration resistance of the nanocrystalline core. It also reduces the risk of partial discharge from air gaps, enhancing electrical safety. Furthermore, this method offers strong process adaptability, allowing for the selection of appropriate implementation schemes based on production scale.

[0066] In some examples, after placing the bare nanocrystalline core within a housing, a potting material is then applied to the housing to fill the gap between the bare nanocrystalline core and the housing. After the potting material cures, not only is zero gap achieved between the bare nanocrystalline core and the housing, but it also helps improve heat dissipation and vibration resistance. Using a potting material with a low coefficient of thermal expansion can further reduce stress caused by temperature changes.

[0067] In this embodiment, the protective shell is wrapped around the outside of the nanocrystalline bare magnetic core by thermoplastic molding, injection molding, heat shrink molding or potting molding, so that the protective shell and the nanocrystalline bare magnetic core are tightly fitted together, realizing a mechanical self-locking structure, which helps to improve the structural strength of both, and helps to improve the mechanical stability, electrical performance and environmental adaptability of the nanocrystalline bare magnetic core, especially suitable for application scenarios with high frequency, high voltage and high reliability requirements.

[0068] In some embodiments, the protective shell may be made of a thermoplastic material with a coefficient of thermal expansion of 1 × 10⁻⁶. -5 / ℃~1×10 -4 / ℃. For example, the material of the protective shell can expand when heated. By setting a mold on the outside of the protective shell, the protective shell expands towards the nanocrystalline bare magnetic core inside, which facilitates the zero-gap fit between the nanocrystalline bare magnetic core and the protective shell.

[0069] For example, the material of the protective shell can shrink when heated. In some embodiments of this application, the material of the protective shell is a heat-shrinkable material.

[0070] Thermo-shrinkable materials refer to special polymeric materials that shrink significantly in size when heated. Examples include heat shrink tubing made of polyolefins (polyethylene), polyvinyl chloride, and fluoropolymers.

[0071] The protective shell of this embodiment is made of a thermo-shrinkable material, so that after the protective shell is heated, it can cover the outside of the nanocrystalline bare magnetic core, which is conducive to achieving zero-gap bonding.

[0072] In some embodiments, the heat shrinkage rate of the protective shell is 20% to 50%.

[0073] By limiting the thermal shrinkage rate of the casing, sufficient shrinkage allowance is ensured to achieve a tight interference fit between the nanocrystalline bare magnetic core and the casing.

[0074] In some embodiments, the temperature resistance of the protective shell is greater than or equal to 120°C.

[0075] By limiting the temperature resistance of the casing, the reliability of the casing is ensured in high-temperature working environments or during processing.

[0076] In some possible implementations of this application, an elastic buffer layer is provided on the inner surface of the protective shell facing the nanocrystalline bare magnetic core.

[0077] The elastic buffer layer can be a silicone layer, a rubber layer, etc.

[0078] This application embodiment provides an elastic buffer layer on the side of the casing facing the nanocrystalline bare magnetic core to absorb the stress caused by the difference in thermal expansion coefficients between the nanocrystalline bare magnetic core and the casing, preventing cracks or gaps from forming under long-term temperature cycling, and thus improving the stability of long-term use.

[0079] This application also provides a method for preparing a nanocrystalline magnetic core, which can prepare the nanocrystalline magnetic core described in the above embodiments.

[0080] The method for preparing the nanocrystalline magnetic core according to the embodiments of this application includes:

[0081] Step S1: Provide an initial protective shell and place it over the outside of the nanocrystalline bare magnetic core.

[0082] The initial protective shell refers to the protective shell that is fitted over the outside of the bare nanocrystalline magnetic core and has a large gap with the bare nanocrystalline magnetic core.

[0083] The initial protective shell has a thickness greater than or equal to 0.5 mm and less than or equal to 2 mm.

[0084] By limiting the thickness of the initial sheath, sufficient structural strength is ensured, and the sheath can tightly enclose the bare nanocrystalline magnetic core after shrinkage.

[0085] The initial sheath and the nanocrystalline bare magnetic core have a single-sided gap of 0.3mm to 1.5mm.

[0086] By limiting the single-sided gap between the initial protective shell and the nanocrystalline bare magnetic core, it is ensured that the nanocrystalline bare magnetic core can be smoothly assembled into the initial protective shell; this avoids the gap between the initial protective shell and the nanocrystalline bare magnetic core being too large, which would result in an excessively large gap between the heat-shrinkable protective shell and the nanocrystalline bare magnetic core; and it also avoids the gap between the initial protective shell and the nanocrystalline bare magnetic core being too small, which would affect the smooth assembly of the nanocrystalline bare magnetic core.

[0087] Step S2: Heat the initial protective shell to thermoplastically deform it and wrap it around the outside of the nanocrystalline bare magnetic core to form a nanocrystalline magnetic core; wherein the interface gap between the nanocrystalline bare magnetic core and the protective shell is less than or equal to 0.1 mm.

[0088] In this embodiment, after the initial protective shell is fitted onto the outside of the nanocrystalline bare magnetic core, it is heated, causing the initial protective shell to shrink and cover the outside of the nanocrystalline bare magnetic core, forming the nanocrystalline magnetic core. The heating method allows the initial protective shell to thermally shrink and adhere to the outside of the nanocrystalline bare magnetic core, which is not only simple to operate and low in cost, facilitating mass production, but also helps ensure a close fit between the protective shell and the nanocrystalline bare magnetic core, contributing to achieving zero gap.

[0089] The protective shell serves to protect the bare nanocrystalline magnetic core, preventing it from mechanical damage and environmental impact. Furthermore, the interface gap between the bare nanocrystalline magnetic core and the protective shell is less than or equal to 0.1 mm, ensuring a tight fit between them and structurally eliminating the mechanical displacement problems caused by pre-existing gaps in the protective shell in existing technologies.

[0090] Moreover, under vibration or shock conditions, the tight fit between the casing and the nanocrystalline bare magnetic core effectively suppresses relative displacement caused by gaps, thereby reducing resonance noise and the risk of structural loosening, ensuring the long-term stability of the nanocrystalline bare magnetic core in complex environments. Furthermore, the tight fit blocks the intrusion paths of moisture and impurities, reducing the possibility of partial discharge and improving electrical safety.

[0091] In some embodiments of this application, heating the initial protective shell includes heating the protective shell in a segmented manner.

[0092] For example, the segmented heating shell can be divided into three stages: preheating, uniform shrinkage, and cooling and curing, with the temperature adjusted by an independent temperature control module.

[0093] For example, the heating temperature in the preheating stage is 80℃, the heating temperature in the uniform shrinkage stage is 120℃, and the temperature is gradually reduced to room temperature in the cooling and curing stage.

[0094] This design allows the initial sheath to shrink uniformly, preventing deformation or stress concentration due to localized overheating. After the initial sheath has shrunk, it achieves surface contact with the nanocrystalline bare magnetic core surface without visible gaps, forming a mechanically self-locking structure that improves structural compactness and vibration resistance.

[0095] In some of these implementations, heating is used to shrink the initial sheath, allowing it to cover the outer surface of the nanocrystalline bare magnetic core and achieve a zero-gap fit.

[0096] In other implementations, a thermoforming process is used to shrink the initial sheath before applying pressure with a mold, causing the sheath to cover the outer surface of the nanocrystalline bare magnetic core, achieving a zero-gap fit. Pressure-assisted shrinkage creates surface contact between the sheath and the nanocrystalline bare magnetic core, optimizing interface adhesion.

[0097] In some specific implementations of this application, the method for preparing the nanocrystalline magnetic core also includes:

[0098] After the initial protective shell is placed over the outside of the nanocrystalline bare magnetic core, it is placed in the mold cavity;

[0099] After heating the initial protective shell, the initial protective shell and the nanocrystalline bare magnetic core are extruded using a mold cavity to form the nanocrystalline magnetic core.

[0100] In this embodiment of the application, after heating the initial protective shell, the initial protective shell and the bare nanocrystalline magnetic core are extruded using a mold cavity to ensure the external dimensions of the nanocrystalline magnetic core and to make the fit between the nanocrystalline magnetic core and the protective shell more uniform and tight.

[0101] In some embodiments, the protective shell may be made of a thermoplastic material with a coefficient of thermal expansion of 1 × 10⁻⁶. -5 / ℃~1×10 -4 / ℃. For example, the material of the protective shell can expand when heated. By setting a mold on the outside of the protective shell, the protective shell expands towards the nanocrystalline bare magnetic core inside, which facilitates the zero-gap fit between the nanocrystalline bare magnetic core and the protective shell.

[0102] For example, the material of the protective shell can shrink when heated. In some embodiments of this application, the material of the protective shell is a heat-shrinkable material.

[0103] Thermo-shrinkable materials refer to special polymeric materials that shrink significantly in size when heated. Examples include heat-shrink tubing, polyolefins (polyethylene), polyvinyl chloride, and fluoropolymers.

[0104] The protective shell of this embodiment is made of a thermo-shrinkable material, so that after the protective shell is heated, it can cover the outside of the nanocrystalline bare magnetic core, which is conducive to achieving zero-gap bonding.

[0105] In some embodiments, the heat shrinkage rate of the protective shell is 20% to 50%.

[0106] By limiting the thermal shrinkage rate of the casing, sufficient shrinkage allowance is ensured to achieve a tight interference fit between the nanocrystalline bare magnetic core and the casing.

[0107] In some embodiments, the temperature resistance of the protective shell is greater than or equal to 120°C.

[0108] By limiting the temperature resistance of the casing, the reliability of the casing is ensured in high-temperature working environments or during processing.

[0109] Example 1

[0110] A toroidal nanocrystalline bare magnetic core with an outer diameter of 30 mm, an inner diameter of 20 mm, and a height of 10 mm was selected, and an initial protective shell of PET (Polyethylene Terephthalate) + 30% glass fiber with an outer diameter of 33 mm, an inner diameter of 17.8 mm, a height of 12.85 mm, and a wall thickness of 1.0 mm was used. After the protective shell and the nanocrystalline bare magnetic core were assembled, they were hot-pressed in a mold until the nanocrystalline bare magnetic core and the protective shell formed an interference fit.

[0111] Specific product images are shown below. Figure 2 As shown, Figure 3 This is a flaw detection morphology image. Combined with... Figure 2 and Figure 3 This indicates that the gap between the protective shell and the bare nanocrystalline magnetic core is not uniform.

[0112] Testing revealed that the interface gap between the nanocrystalline bare magnetic core and the protective shell was 0.05 mm, which is less than 0.1 mm, meeting the definition of "zero gap". Furthermore, the attenuation of the nanocrystalline magnetic core after hot pressing was less than 5%.

[0113] The table below shows the inductance and impedance at different frequencies when a magnetic field of 100mT is applied to a bare nanocrystalline magnetic core and the induced voltage across the test coil is 30mV. The table shows that the attenuation rate of both inductance and impedance is less than 5% before and after hot pressing.

[0114]

[0115] Example 2

[0116] A toroidal nanocrystalline bare magnetic core with an outer diameter of 25.0 mm was selected, and a polyolefin heat shrink tubing with an inner diameter of 28.0 mm and a wall thickness of 1.0 mm was used. After heating in a 120℃ constant temperature oven for 60 seconds, the inner diameter of the heat shrink tubing decreased to 25.1 mm, forming an interference fit with the outer surface of the nanocrystalline bare magnetic core. Testing showed that the gap between the nanocrystalline bare magnetic core and the protective shell was less than 0.05 mm, meeting the definition of "zero gap".

[0117] This application also provides an electronic device comprising the nanocrystalline magnetic core described in the above embodiments.

[0118] Since the electronic device includes the nanocrystalline magnetic core of the above embodiments, the electronic device of the present application embodiments also has the same advantages as the above nanocrystalline magnetic core, which will not be repeated here.

[0119] This application also provides an electronic device comprising a nanocrystalline magnetic core prepared by the preparation method described above.

[0120] Since the electronic device includes the nanocrystalline magnetic core prepared by the preparation method of the above embodiments, the electronic device of this application embodiment also has the same advantages as the nanocrystalline magnetic core prepared by the above preparation method, and will not be repeated here.

[0121] The electronic devices in the embodiments of this application may be high-frequency transformers, inductors, etc., and the embodiments of this application do not limit them.

[0122] In the above description, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A nanocrystalline magnetic core, characterized in that, include: The nanocrystalline bare magnetic core and the sheath, wherein the sheath covers the outside of the nanocrystalline bare magnetic core and the interface gap between the nanocrystalline bare magnetic core and the sheath is less than or equal to 0.1 mm.

2. The nanocrystalline magnetic core according to claim 1, characterized in that, The protective shell is applied to the outside of the bare nanocrystalline magnetic core by thermoplastic molding, injection molding, heat shrink molding, or potting.

3. The nanocrystalline magnetic core according to claim 1, characterized in that, The protective shell is made of a heat-shrinkable material.

4. The nanocrystalline magnetic core according to claim 1, characterized in that, The protective shell is made of thermoplastic material, and its coefficient of thermal expansion is 1×10⁻⁶. -5 / ℃~1×10 -4 / ℃.

5. The nanocrystalline magnetic core according to claim 1, characterized in that, The temperature resistance of the protective shell is greater than or equal to 120°C.

6. A method for preparing a nanocrystalline magnetic core, characterized in that, include: Provide an initial protective shell and fit the initial protective shell over the outside of the nanocrystalline bare magnetic core; The initial protective shell is heated to thermoplastically deform it and wrap it around the outside of the nanocrystalline bare magnetic core to form the nanocrystalline magnetic core; wherein the interface gap between the nanocrystalline bare magnetic core and the protective shell is less than or equal to 0.1 mm.

7. The method for preparing a nanocrystalline magnetic core according to claim 6, characterized in that, The initial protective shell has a thickness greater than or equal to 0.5 mm and less than or equal to 2 mm; and / or, the single-sided gap between the initial protective shell and the nanocrystalline bare magnetic core is 0.3 mm to 1.5 mm.

8. The method for preparing a nanocrystalline magnetic core according to claim 6, characterized in that, Heating the initial protective shell includes: The protective shell is heated using a segmented heating method.

9. The method for preparing a nanocrystalline magnetic core according to claim 6, characterized in that, The preparation method further includes: After the initial protective shell is fitted over the outside of the nanocrystalline bare magnetic core, it is placed in the mold cavity; After heating the initial protective shell, the initial protective shell and the nanocrystalline bare magnetic core are extruded using a mold cavity to form the nanocrystalline magnetic core.

10. An electronic device, characterized in that, Includes the nanocrystalline magnetic core according to any one of claims 1-5; or includes the nanocrystalline magnetic core prepared by the method for preparing the nanocrystalline magnetic core according to any one of claims 6-9.

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