A thermosetting packaged integrated inductor and a manufacturing method thereof

Abstract

The present invention discloses a thermosetting packaged integrated inductor and a manufacturing method thereof, which belongs to the technical field of inductors. The inductor comprises a low-impedance eddy current core, an inductor coil and a thermally conductive thermosetting polymer packaging material. The thermally conductive thermosetting polymer packaging material integrates the low-impedance eddy current core and the inductor coil. The thermally conductive thermosetting polymer packaging material has electrical insulation and thermal conductivity. The low-impedance eddy current core is pressed from a high-permeability mixed crystal phase alloy powder wrapped with a silicon dioxide film; the thickness of the silicon dioxide film is controlled to be below 50 μm and above 20 μm. The present application effectively improves the thermal conductivity of the inductor by adopting a thermally conductive thermosetting polymer packaging material. Compared with traditional inductors, the thermal conductivity coefficient is increased by more than 40%, the core loss is reduced by more than 30%, the thermal impact of the inductor on surrounding components during operation is reduced, and the thermal stability of the entire circuit is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of inductors, and in particular to a thermosetting packaged integrated inductor and a manufacturing method thereof. Background Art

[0002] An inductor is an electronic component that operates on the principle of electromagnetic induction, converting electrical energy into magnetic energy and storing it. When alternating current passes through an inductor, the magnetic field generated by the current changes. According to Faraday's law of electromagnetic induction, this magnetic field change generates an electromotive force in the coil in the opposite direction, thereby hindering the change in current. Conversely, when the current decreases, the inductor generates an electromotive force in the direction of increasing the current, hindering the decrease in current. This characteristic of the inductor makes the current flow in the circuit smoother, can reduce the sharp changes in current during switching, and can play a role in filtering signals, filtering noise, stabilizing current, and suppressing electromagnetic interference.

[0003] The integrated inductor in the existing technology has the following defects: first, the traditional alloy magnetic powder core material has low resistivity, large eddy current at high frequency, and severe heat generation; second, the packaging material of the integrated inductor is usually modified epoxy resin, which has low thermal conductivity and poor thermal conductivity. Summary of the Invention

[0004] The present invention aims to provide a thermoset-encapsulated integrated inductor and its manufacturing method. This inductor, shielded by a silicon dioxide film, prevents the generated induced current from forming eddy currents in the magnetic core, significantly reducing heat generated by the core and eddy current losses at high frequencies.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A thermoset-packaged integrated inductor comprises a low-impedance eddy-current magnetic core, an inductor coil, and a thermally conductive thermosetting polymer packaging material. The thermally conductive thermosetting polymer packaging material integrally packages the low-impedance eddy-current magnetic core and the inductor coil. The thermally conductive thermosetting polymer packaging material has both electrical insulation and thermal conductivity. The low-impedance eddy-current magnetic core is formed by pressing high-permeability mixed crystal phase alloy powder coated with a silicon dioxide film, and has low thermal conductivity and high insulation resistance characteristics. The thickness of the silicon dioxide film is controlled to be below 50 μm and above 20 μm.

[0007] Furthermore, the high permeability mixed crystal phase alloy powder is represented by a composition formula of FeaNibCocPdCue, wherein 70≤a≤80at%, 10≤b≤20at%, 1≤c≤3at%, 6≤d≤8at%, 0.4≤e≤0.6at% and a+b+c+d+e=100at%, and the high permeability mixed crystal phase alloy powder is composed of an amorphous phase with a volume ratio of 82-88% and a crystalline phase of 12-18%.

[0008] Furthermore, the thermally conductive thermosetting polymer packaging material is a mixture of polyimide resin, aluminum oxide powder and boron nitride powder, wherein the mass percentage of polyimide resin is 80-90%, the mass percentage of aluminum oxide powder is 6-12%, and the mass percentage of boron nitride powder is 4-8%.

[0009] Furthermore, the preparation method of the low-impedance eddy-current magnetic core is as follows:

[0010] Step 1. Weigh and uniformly mix the components of the composition formula FeaNibCocPdCue in a ratio of 70≤a≤80at%, 10≤b≤20at%, 1≤c≤3at%, 6≤d≤8at%, 0.4≤e≤0.6at%, and a+b+c+d+e=100at%. Press the mixture into a block without adding a binder, perform a first heat treatment, and then grind the block to obtain a high permeability crystalline alloy powder.

[0011] Step 2. Coating a silicon dioxide film on the surface of the high permeability crystalline alloy powder: The specific steps of the silicon dioxide film coating are as follows: dispersing the high permeability crystalline alloy powder in an ethanol aqueous solution, adding a catalyst and continuously stirring, and dispersing by ultrasonication for 10 to 20 minutes, then adding tetraethyl orthosilicate dropwise using a peristaltic pump at a speed of 20 to 30 rpm, continuously stirring and ultrasonicating until the addition is complete, then maintaining ultrasonication for 6 to 8 minutes and then turning off the ultrasonication, continuously stirring to react for 7 to 9 hours, and drying to obtain a high permeability crystalline alloy powder coated with a silicon dioxide film;

[0012] Step 3. Place the high permeability crystalline alloy powder into a low-impedance eddy current magnetic core forming mold and press it into a magnetic core blank without adding a binder;

[0013] Step 4. Perform a second heat treatment and annealing treatment: Perform a second heat treatment on the core blank in an inert gas environment, and then perform an annealing treatment to obtain a low-impedance eddy current core.

[0014] Furthermore, in step 1, the temperature of the first heat treatment is 420-440°C.

[0015] Furthermore, in step 2, the catalyst is aqueous ammonia or tetramethylammonium hydroxide.

[0016] Furthermore, in step 3, the pressure used for pressing is 2.1-2.3 GPa.

[0017] Furthermore, in step 4, the temperature of the second heat treatment is 580-600° C., the temperature of the annealing treatment is 280-300° C., and the annealing time is 1.5-2 hours.

[0018] A method for manufacturing a thermosetting packaged integrated inductor comprises the following steps:

[0019] S1. According to the mass percentage content of 80-90%, 6-12%, 4-8%, polyimide resin particles, alumina powder and boron nitride powder were weighed, and thoroughly mixed to obtain a thermally conductive thermosetting polymer encapsulation material;

[0020] S2. heating and melting the thermally conductive thermosetting polymer encapsulation material;

[0021] S3. The prepared low-impedance eddy-current magnetic core has a cylindrical structure with slots provided at both ends of the cylindrical low-impedance eddy-current magnetic core. The ends of the two copper electrode sheets are coated with a layer of thermally conductive thermosetting polymer encapsulation material and then inserted into the slots at both ends of the low-impedance eddy-current magnetic core. The wound inductor coil is placed and inserted on the low-impedance eddy-current magnetic core and adjusted to a predetermined position. The two leads of the inductor coil are respectively welded to the two copper electrode sheets. The low-impedance eddy-current magnetic core and the inductor coil are placed together in the lower mold of the plastic molding mold, with the copper electrode sheets extending from both ends of the plastic molding mold. The two ends of the low-impedance eddy-current magnetic core are supported by the copper electrode sheets. A predetermined gap is maintained between the low-impedance eddy-current magnetic core and the inner wall of the plastic molding mold. The upper mold and the lower mold in the plastic molding mold are tightly fastened together.

[0022] S4. The plastic mold is vacuumed and the melted heat-conductive thermosetting polymer encapsulation material is filled into the mold cavity of the plastic mold. The filling pressure is 8-10MPa and the temperature is 260 - 400 ℃.

[0023] S5. After the filling and packaging is completed, a curing treatment is performed at a curing temperature of 130-180°C and a curing time of 1.5-2 hours, so that the thermally conductive thermosetting polymer packaging material is completely cured and tightly combined with the low-impedance eddy current core and the inductor coil to form an integrally molded packaged inductor.

[0024] Furthermore, the vacuum degree of the plastic packaging mold is maintained in the range of 0.9-1 MPa.

[0025] The beneficial effects of the present invention are:

[0026] The thermoset-encapsulated integrated inductor of the present application greatly reduces eddy current losses at high frequencies: the inductor core adopts a low-impedance eddy current core with low thermal conductivity and high insulation impedance characteristics. Under the barrier of the silicon dioxide film, the generated induced current is prevented from forming eddy currents in the core, which greatly reduces the heat energy generated by the core and greatly reduces the eddy current losses at high frequencies.

[0027] The thermoset encapsulated integrated inductor of the present application has excellent electrical insulation and thermal conductivity: by adopting a thermally conductive thermosetting polymer encapsulation material, the thermal conductivity of the inductor is effectively improved. Compared with traditional inductors, the thermal conductivity coefficient is increased by more than 40%, and the core loss is reduced by more than 30%. The thermal impact of the inductor on surrounding components during operation is reduced, and the thermal stability of the entire circuit is improved.

[0028] The manufacturing process of the thermoset encapsulated integrated inductor of this application is simplified and the cost is reduced: the casting encapsulation greatly reduces the number of production processes and parts, improves production efficiency, and reduces production costs. Compared with the traditional inductor manufacturing process, the production efficiency is increased by more than 30% and the cost is reduced by more than 10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not limit the present invention in any way. A person skilled in the art can derive other drawings based on the following drawings without inventive effort.

[0030] Figure 1 It is a schematic structural diagram of the thermosetting packaged integrated inductor of the present invention.

[0031] In the figure: 1. Low-impedance eddy-current core; 2. Inductor coil; 3. Thermally conductive thermosetting polymer packaging material; 4. Copper electrode sheet; 5. Slot; 6. Lead wire. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features therein can be combined with each other unless there is a conflict.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper surface", "lower surface", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "forward", "reverse", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0034] like Figure 1As shown, a thermoset encapsulated integrated inductor includes a low-impedance eddy current magnetic core 1, an inductor coil 2 and a thermally conductive thermosetting polymer encapsulation material 3. The ends of two copper electrode sheets 4 are coated with a layer of thermally conductive thermosetting polymer encapsulation material and then inserted into slots 5 at both ends of the low-impedance eddy current magnetic core 1. The two leads 6 of the inductor coil 2 are respectively welded to the two copper electrode sheets 4. The thermally conductive thermosetting polymer encapsulation material 3 integrates the low-impedance eddy current magnetic core 1 and the inductor coil 2.

[0035] The low-impedance eddy-current core 1 is compacted from high-permeability mixed-phase alloy powder coated with a silicon dioxide film, exhibiting low thermal conductivity and high insulation resistance. The high-permeability mixed-phase alloy powder is represented by the composition formula FeaNibCocPdCue, where 70 ≤ a ≤ 80 at%, 10 ≤ b ≤ 20 at%, 1 ≤ c ≤ 3 at%, 6 ≤ d ≤ 8 at%, 0.4 ≤ e ≤ 0.6 at%, and a + b + c + d + e = 100 at%. The high-permeability mixed-phase alloy powder is composed of an amorphous phase with a volume ratio of 82-88% and a crystalline phase of 12-18%. The silicon dioxide film thickness is controlled to be below 50 μm and above 20 μm. The thickness of the silicon dioxide film will have a certain impact on the magnetic permeability. Therefore, the thickness of the silicon dioxide film should be controlled below 50μm. In order to ensure high insulation resistance characteristics and reduce eddy current loss of the magnetic core, the thickness of the silicon dioxide film should be controlled to be above 20μm.

[0036] The surface of the high permeability mixed crystal phase alloy powder is coated with a silicon dioxide film. The silicon dioxide film has excellent electrical insulation properties and can prevent the induced current from forming eddy currents in the magnetic core, greatly reducing the heat energy generated by the magnetic core and greatly reducing the eddy current loss at high frequencies. However, due to the low magnetic permeability of the silicon dioxide film, it is necessary to improve the material of the magnetic core 1 to maximize the magnetic permeability and increase the magnetic flux. In the Fe base, increasing the Ni content can increase the magnetic permeability, but increasing the Ni content will increase the manufacturing cost. Therefore, the high permeability mixed crystal phase alloy powder in the low-conductivity eddy current magnetic core 1 of the present application adopts the above-mentioned composition formula FeaNibCocPdCue, wherein, in order to maximize the magnetic permeability of the magnetic core, the Ni content is adjusted to above 10at%, and in order to reduce costs, the Ni content is adjusted to below 20at%, and at the same time, an appropriate amount of Co element is added.

[0037] The element P is essential for the formation of the amorphous phase. High-permeability mixed-crystal alloy powders with 82-88% amorphous phase have very high magnetic permeability. In this embodiment, P is added to the magnetic core material, and the P ratio is adjusted within the range of 6 ≤ d ≤ 8 at%. Specifically, when the P ratio is greater than 6 at%, the viscosity of the alloy melt during magnetic powder production can be significantly reduced, thereby improving the magnetic properties of the pressed powder core and facilitating the production of spherical magnetic powders. In particular, the melting point of P is 44.1°C. The low melting point of P improves the ability to generate amorphous phases, making it easier to produce Fe-based crystalline alloy powders. To achieve the desired saturation magnetic flux density Bs in the Fe-based nanocrystalline alloy powder, the P ratio is adjusted to below 8 at%. When the ratios of other elements in the low-impedance eddy current magnetic core 1 remain unchanged, a P ratio of 7 at% achieves excellent saturation magnetic flux density Bs and excellent magnetic properties.

[0038] In the present embodiment, the Cu element is added to the magnetic core material, and preferably the proportion of the Cu element is adjusted to be above 0.4at% and below 0.6at%. Within this proportion range, the effect of refining the crystals in the Fe-based crystal alloy powder can be obtained, and the amorphous forming ability can be improved. As a result, the deterioration of the magnetic properties of the Fe-based crystal alloy powder caused by the early precipitates can be suppressed. Specifically, in order to prevent the coarsening of nanocrystals in the Fe-based crystal alloy powder, thereby causing core loss, the proportion of Cu should be set to be above 0.4at%. In order to improve the ability to generate amorphous forms, the crystalline phase in the high permeability mixed crystal phase alloy powder is controlled to be below 18%, and the proportion of Cu is adjusted to be below 0.6at%. In addition, in order to increase the amount of crystal precipitation and increase the saturation magnetic flux density Bs of the Fe-based crystal alloy powder, the proportion of Cu is preferably 0.5at%.

[0039] After adopting the above-mentioned high permeability mixed crystal phase alloy powder, this application maximizes the magnetic permeability while controlling the manufacturing cost to compensate for the influence of the silicon dioxide film on the magnetic flux of the magnetic core, thereby ensuring the required magnetic permeability of the magnetic core while suppressing the eddy current loss and heat generation of the magnetic core.

[0040] The packaging of this application utilizes a thermally conductive thermosetting polymer packaging material that exhibits both electrical insulation and thermal conductivity. The material is composed of a mixture of polyimide resin, aluminum oxide powder, and boron nitride powder. The polyimide resin comprises 80-90% by weight, the aluminum oxide powder 6-12% by weight, and the boron nitride powder 4-8% by weight. The aluminum oxide and boron nitride powders not only enhance the packaging material's insulation properties but also significantly improve its thermal conductivity, enabling the inductor to operate normally and stably under high-frequency conditions.

[0041] Example 1

[0042] A method for manufacturing a thermosetting packaged integrated inductor comprises the following steps:

[0043] S1. Weigh polyimide resin particles, aluminum oxide powder, and boron nitride powder in respective mass percentages of 80%, 12%, and 8%, respectively, and thoroughly mix them to obtain a thermally conductive thermosetting polymer encapsulation material.

[0044] S2. heating and melting the heat-conductive thermosetting polymer packaging material.

[0045] S3. The prepared low-impedance eddy current core has a columnar structure, and slots are provided at both ends of the columnar low-impedance eddy current core. The ends of the two copper electrode sheets are coated with a layer of heat-conductive thermosetting polymer packaging material and then inserted into the slots at both ends of the low-impedance eddy current core. The wound inductor coil is placed and inserted on the low-impedance eddy current core and adjusted to a predetermined position. The two leads of the inductor coil are respectively welded to the two copper electrode sheets. The low-impedance eddy current core and the inductor coil are placed together in the lower mold of the plastic molding mold. The copper electrode sheets extend from both ends of the plastic molding mold. The two ends of the low-impedance eddy current core are supported by the copper electrode sheets. A predetermined gap is retained between the low-impedance eddy current core and the inner wall of the plastic molding mold. The upper mold and the lower mold in the plastic molding mold are tightly buckled together.

[0046] The preparation method of the low-impedance eddy-current magnetic core is as follows:

[0047] Step 1. Weigh and uniformly mix the components of the composition formula (FeaNibCocPdCue) in proportions of 70 at%, 20 at%, 1.6 at%, 8 at%, and 0.4 at%. Press the mixture into blocks without adding a binder, perform a first heat treatment, and then grind the blocks to obtain a high-permeability crystalline alloy powder. The temperature of the first heat treatment is 420°C.

[0048] Step 2. Coating the high-permeability crystalline alloy powder with a silica film: The silica film coating process includes dispersing the high-permeability crystalline alloy powder in an aqueous ethanol solution, adding a catalyst, stirring continuously, and dispersing by ultrasonication for 10 minutes. Tetraethyl orthosilicate is then added dropwise using a peristaltic pump at a rate of 20 rpm. Stirring and ultrasonication are continued until the addition is complete. Ultrasonication is maintained for 6 minutes, then turned off. Stirring is continued for 7 hours, and drying is performed to obtain the high-permeability crystalline alloy powder coated with a silica film. The catalyst is aqueous ammonia or tetramethylammonium hydroxide. The silica film has a thickness of 50 μm.

[0049] Step 3. Place the high permeability crystalline alloy powder into a low-impedance eddy current magnetic core forming mold and press it into a magnetic core blank without adding a binder; the pressing pressure is 2.1 GPa.

[0050] Step 4. Perform a second heat treatment and annealing treatment: Perform a second heat treatment on the core blank in an inert gas environment, and then perform an annealing treatment to obtain a low-impedance eddy current core; the temperature of the second heat treatment is 580°C, the temperature of the annealing treatment is 280°C, and the annealing time is 1.5 hours.

[0051] S4. The plastic mold is evacuated, the vacuum degree of the plastic mold is maintained within the range of 0.9MPa, and the thermally conductive thermosetting polymer encapsulation material after heating and melting is filled into the mold cavity of the plastic mold, the filling packaging pressure is 8MPa, and the temperature is 260 ℃;

[0052] S5. After the filling and packaging are completed, a curing process is performed at a curing temperature of 130°C and a curing time of 1.5 hours, so that the thermally conductive thermosetting polymer packaging material is completely cured and tightly combined with the low-impedance eddy current core and the inductor coil to form an integrally molded packaged inductor.

[0053] Example 2

[0054] A method for manufacturing a thermosetting packaged integrated inductor comprises the following steps:

[0055] S1. Weigh polyimide resin particles, aluminum oxide powder, and boron nitride powder in respective mass percentages of 85%, 9%, and 6%, respectively, and thoroughly mix them to obtain a thermally conductive thermosetting polymer encapsulation material.

[0056] S2. heating and melting the heat-conductive thermosetting polymer packaging material.

[0057] S3. The prepared low-impedance eddy current core has a columnar structure, and slots are provided at both ends of the columnar low-impedance eddy current core. The ends of the two copper electrode sheets are coated with a layer of heat-conductive thermosetting polymer packaging material and then inserted into the slots at both ends of the low-impedance eddy current core. The wound inductor coil is placed and inserted on the low-impedance eddy current core and adjusted to a predetermined position. The two leads of the inductor coil are respectively welded to the two copper electrode sheets. The low-impedance eddy current core and the inductor coil are placed together in the lower mold of the plastic molding mold. The copper electrode sheets extend from both ends of the plastic molding mold. The two ends of the low-impedance eddy current core are supported by the copper electrode sheets. A predetermined gap is retained between the low-impedance eddy current core and the inner wall of the plastic molding mold. The upper mold and the lower mold in the plastic molding mold are tightly buckled together.

[0058] The preparation method of the low-impedance eddy-current magnetic core is as follows:

[0059] Step 1. Weigh and uniformly mix the components of the composition formula (FeaNibCocPdCue) in proportions of 80 at%, 10 at%, 3 at%, 6.4 at%, and 0.6 at%. Press the mixture into blocks without adding a binder, perform a first heat treatment, and then grind the blocks to obtain a high-permeability crystalline alloy powder. The temperature of the first heat treatment is 440°C.

[0060] Step 2. Coating the high-permeability crystalline alloy powder with a silica film: The silica film coating process includes dispersing the high-permeability crystalline alloy powder in an aqueous ethanol solution, adding a catalyst, stirring continuously, and dispersing under ultrasonication for 20 minutes. Tetraethyl orthosilicate is then added dropwise using a peristaltic pump at a rate of 30 rpm. Stirring and ultrasonication are continued until the addition is complete. Ultrasonication is maintained for an additional 8 minutes, then turned off. Stirring is continued for 9 hours, and drying is performed to obtain the high-permeability crystalline alloy powder coated with a silica film. The catalyst is aqueous ammonia or tetramethylammonium hydroxide. The silica film has a thickness of 20 μm.

[0061] Step 3. Place the high permeability crystalline alloy powder into a low-impedance eddy current magnetic core forming mold and press it into a magnetic core blank without adding an adhesive; the pressing pressure is 2.3 GPa.

[0062] Step 4. Perform a second heat treatment and annealing treatment: Perform a second heat treatment on the core blank in an inert gas environment, and then perform an annealing treatment to obtain a low-impedance eddy current core; the temperature of the second heat treatment is 600°C, the temperature of the annealing treatment is 300°C, and the annealing time is 2 hours.

[0063] S4. The plastic mold is evacuated, the vacuum degree of the plastic mold is maintained within the range of 1MPa, and the heat-conductive thermosetting polymer encapsulation material after heating and melting is filled into the mold cavity of the plastic mold, the filling packaging pressure is 10MPa, and the temperature is 400 ℃;

[0064] S5. After the filling and packaging is completed, a curing process is performed at a curing temperature of 180°C and a curing time of 2 hours, so that the thermally conductive thermosetting polymer packaging material is completely cured and tightly combined with the low-impedance eddy current core and the inductor coil to form an integrally molded packaged inductor.

[0065] Example 3

[0066] A method for manufacturing a thermosetting packaged integrated inductor comprises the following steps:

[0067] S1. Weigh polyimide resin particles, aluminum oxide powder, and boron nitride powder in respective mass percentages of 90%, 6%, and 4%, respectively, and thoroughly mix them to obtain a thermally conductive thermosetting polymer encapsulation material.

[0068] S2. heating and melting the heat-conductive thermosetting polymer packaging material.

[0069] S3. The prepared low-impedance eddy current core has a columnar structure, and slots are provided at both ends of the columnar low-impedance eddy current core. The ends of the two copper electrode sheets are coated with a layer of heat-conductive thermosetting polymer packaging material and then inserted into the slots at both ends of the low-impedance eddy current core. The wound inductor coil is placed and inserted on the low-impedance eddy current core and adjusted to a predetermined position. The two leads of the inductor coil are respectively welded to the two copper electrode sheets. The low-impedance eddy current core and the inductor coil are placed together in the lower mold of the plastic molding mold. The copper electrode sheets extend from both ends of the plastic molding mold. The two ends of the low-impedance eddy current core are supported by the copper electrode sheets. A predetermined gap is retained between the low-impedance eddy current core and the inner wall of the plastic molding mold. The upper mold and the lower mold in the plastic molding mold are tightly buckled together.

[0070] The preparation method of the low-impedance eddy-current magnetic core is as follows:

[0071] Step 1. Weigh and uniformly mix the components of the composition formula FeaNibCocPdCue in proportions of 75 at%, 15 at%, 2.5 at%, 7 at%, and 0.5 at%. Press the mixture into blocks without adding a binder, perform a first heat treatment, and then grind the blocks to obtain a high-permeability crystalline alloy powder; the temperature of the first heat treatment is 430°C.

[0072] Step 2. Coating the high-permeability crystalline alloy powder with a silica film: The silica film coating process is as follows: the high-permeability crystalline alloy powder is dispersed in an ethanol-water solution, a catalyst is added, and continuous stirring is performed. Ultrasonic dispersion is then applied for 15 minutes. Tetraethyl orthosilicate is then added dropwise using a peristaltic pump at a rate of 25 rpm. Stirring and ultrasonication are continued until the addition is complete. Ultrasonication is then maintained for 7 minutes, then turned off. Stirring is continued for 8 hours, and drying is performed to obtain the high-permeability crystalline alloy powder coated with a silica film. The catalyst is aqueous ammonia or tetramethylammonium hydroxide. The silica film has a thickness of 35 μm.

[0073] Step 3. Place the high permeability crystalline alloy powder into a low-impedance eddy current magnetic core forming mold and press it into a magnetic core blank without adding an adhesive; the pressing pressure is 2.2 GPa.

[0074] Step 4. Perform a second heat treatment and annealing treatment: Perform a second heat treatment on the core blank in an inert gas environment, and then perform an annealing treatment to obtain a low-impedance eddy current core; the temperature of the second heat treatment is 590° C., the temperature of the annealing treatment is 290° C., and the annealing time is 1.75 hours.

[0075] S4. The plastic mold is evacuated, the vacuum degree of the plastic mold is maintained within the range of 0.95MPa, and the heat-conductive thermosetting polymer encapsulation material after heating and melting is filled into the mold cavity of the plastic mold, the filling package pressure is 9MPa, and the temperature is 330 ℃;

[0076] S5. After the filling and packaging is completed, a curing process is performed at a curing temperature of 155°C and a curing time of 1.75 hours, so that the thermally conductive thermosetting polymer packaging material is completely cured and tightly combined with the low-impedance eddy current core and the inductor coil to form an integrally molded packaged inductor.

[0077] Experimental testing

[0078] The following experiments were performed on the above three embodiments:

[0079] 1. Core loss P of low-impedance eddy-current core X Test: IWATSU-SY-8218 hysteresis loop instrument is used to test the core loss P X (f=1MHz, B=10mT).

[0080] 2. Magnetic permeability μ test of low-impedance eddy-current core: Use an inductance precision analyzer to test the initial magnetic permeability μ (1 MHz) of the low-impedance eddy-current core.

[0081] The core loss P of the low-impedance eddy current core made in Examples 1-3 is X The test results are shown in Table 1:

[0082] Table 1 Core loss PX measurement results of low-impedance eddy-current cores of three embodiments

[0083] Low-impedance eddy current core Example 1 Example 2 Example 3 average <![CDATA[Core loss P X (mW / cm 3 )]]> 8 7 9 8

[0084] As shown in Table 1, the low-impedance eddy-current cores are made by improving the high-permeability crystalline alloy powder material and coating the surface with a silicon dioxide film. Under the action of the silicon dioxide film, the average value of the low-impedance eddy-current cores made in the three embodiments reaches 8mW / cm 3 Compared with the commonly used inductor cores on the market, the core loss P is greatly reduced. X , core loss is reduced by more than 30%.

[0085] The magnetic permeability μ of the low-impedance eddy-current magnetic cores prepared in Examples 1-3 was tested, and the measurement results are shown in Table 2:

[0086] Table 2 Magnetic permeability μ measurement results of low-impedance eddy-current cores of three embodiments

[0087] Low-impedance eddy current core Example 1 Example 2 Example 3 average Magnetic permeability μ 56 67 63 62

[0088] As can be seen from Table 2, the low-impedance eddy-current core is coated with a silicon dioxide film on the surface of the high-permeability crystalline alloy powder material. By controlling the thickness of the silicon dioxide film, the effect of the silicon dioxide film on the magnetic permeability is greatly reduced. By improving the high-permeability crystalline alloy powder material to maximize the magnetic permeability, under the influence of the silicon dioxide film, the average magnetic permeability μ of the core can reach 62, which is basically the same as the magnetic permeability of 60 of the magnetic cores commonly used in inductors on the market.

[0089] In addition, the thermal conductivity of the thermally conductive thermosetting polymer packaging material of the thermosetting encapsulated integrated inductor was also tested: When testing the thermal conductivity of the thermally conductive thermosetting polymer packaging material, this application uses the Guarded Heat Flow Meter Method (GHFM). Principle: Based on the heat flow meter method, a thermal protection furnace is provided on all sides to ensure that the heat flow in the test area is as uniform as possible and to prevent heat from escaping along the edges. Advantages: Suitable for samples with high thermal conductivity, reducing the impact of lateral heat loss. Scope of application: Samples with thermal conductivity between 0.1W / (m·K) and 40W / (m·K). The existing technology uses modified epoxy resin to seal the inductor. Compared with the modified epoxy resin, the thermally conductive thermosetting polymer packaging material of this application has a thermal conductivity increased by more than 40%.

[0090] In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are mutually inconsistent. Although the embodiments of the present invention have been shown and described above, it should be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A thermosetting packaged integrated inductor, characterized by: The invention comprises a low-impedance eddy current magnetic core, an inductor coil and a thermally conductive thermosetting polymer packaging material. The thermally conductive thermosetting polymer packaging material integrally packages the low-impedance eddy current magnetic core and the inductor coil. The thermally conductive thermosetting polymer packaging material has electrical insulation and thermal conductivity. The low-impedance eddy current magnetic core is pressed from a high-permeability mixed crystal phase alloy powder wrapped with a silicon dioxide film, and has low thermal conductivity and high insulation resistance. The thickness of the silicon dioxide film is controlled to be below 50 μm and above 20 μm. The high-permeability mixed crystal phase alloy powder is represented by the composition formula FeaNibCocPdCue, wherein 70≤a≤80at%, 10≤b≤20at%, 1≤c≤3at%, 6≤d≤8at%, 0.4≤e≤0. .6at% and a+b+c+d+e=100at%, the high permeability mixed crystal phase alloy powder is composed of an amorphous phase with a volume ratio of 82-88% and a crystalline phase of 12-18%.

2. The thermoset packaged integrated inductor according to claim 1, characterized in that: The thermal conductive thermosetting polymer packaging material is a mixture of polyimide resin, aluminum oxide micropowder and boron nitride micropowder, wherein the mass percentage of the polyimide resin is 80-90%, the mass percentage of the aluminum oxide micropowder is 6-12%, and the mass percentage of the boron nitride micropowder is 4-8%.

3. The thermoset packaged integrated inductor according to claim 2, wherein: The preparation method of the low-impedance eddy-current magnetic core is as follows: Step 1. Weigh and uniformly mix the components of the composition formula FeaNibCocPdCue in a ratio of 70≤a≤80at%, 10≤b≤20at%, 1≤c≤3at%, 6≤d≤8at%, 0.4≤e≤0.6at%, and a+b+c+d+e=100at%. Press the mixture into a block without adding a binder, perform a first heat treatment, and then grind the block to obtain a high permeability crystalline alloy powder. Step 2. Coating a silicon dioxide film on the surface of the high permeability crystalline alloy powder: The specific steps of the silicon dioxide film coating are as follows: dispersing the high permeability crystalline alloy powder in an ethanol aqueous solution, adding a catalyst and continuously stirring, and dispersing by ultrasonication for 10 to 20 minutes, then adding tetraethyl orthosilicate dropwise using a peristaltic pump at a speed of 20 to 30 rpm, continuously stirring and ultrasonicating until the addition is complete, then maintaining ultrasonication for 6 to 8 minutes and then turning off the ultrasonication, continuously stirring to react for 7 to 9 hours, and drying to obtain a high permeability crystalline alloy powder coated with a silicon dioxide film; Step 3. Place the high permeability crystalline alloy powder into a low-impedance eddy current magnetic core forming mold and press it into a magnetic core blank without adding a binder; Step 4. Perform a second heat treatment and annealing treatment: Perform a second heat treatment on the core blank in an inert gas environment, and then perform an annealing treatment to obtain a low-impedance eddy current core.

4. The thermoset packaged integrated inductor according to claim 3, characterized in that: In the step 1, the temperature of the first heat treatment is 420-440°C.

5. The thermoset packaged integrated inductor according to claim 4, characterized in that: In step 2, the catalyst is aqueous ammonia or tetramethylammonium hydroxide.

6. The thermosetting packaged integrated inductor according to claim 5, characterized in that: In step 3, the pressing pressure is 2.1-2.3 GPa.

7. The thermosetting packaged integrated inductor according to claim 6, characterized in that: In step 4, the temperature of the second heat treatment is 580-600° C., the temperature of the annealing treatment is 280-300° C., and the annealing time is 1.5-2 hours.

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