A low-loss integrally molded inductor and its fabrication method

Abstract

This invention relates to the field of soft magnetic composite materials and electronic component fabrication technology, and particularly to a low-loss integrally molded inductor and its fabrication method, comprising a magnet and a winding; the winding is a straight structure parallel to the width direction of the magnet, at least a portion of the winding is embedded inside the magnet, and both ends of the winding extend from the opposite surface of the magnet to form protruding structures, the protrusion height of which is 0.1–0.5 mm, and the protruding portion of the protruding structure is trapezoidal, with the hypotenuse angle of the trapezoid being 45°–85°; the magnet is formed by pressing and curing a soft magnetic composite material, which includes Fe-based nanocrystalline powder, alloy powder, and composite resin. Compared with the prior art, the low-loss integrally molded inductor and its fabrication method of this invention can solve the problems of low Q value, high loss, high DC resistance, and high end-welding interface loss of existing integrally molded inductors under high-frequency operating conditions.

Description

[Technical Field] This invention relates to the field of soft magnetic composite materials and electronic component manufacturing technology, and particularly to a low-loss integrally molded inductor and its manufacturing method. [Background Technology] As high-performance servers, power modules, and wide-bandgap semiconductor power systems develop towards higher power density and higher frequency, inductor devices need to balance higher energy storage capacity, higher Q value, lower DC resistance, and lower high-frequency loss within a limited package size.

[0001] One main technical approach for existing molded inductors focuses on optimizing winding lead paths, electrode lead positions, and end metallization structures to reduce lead resistance and improve mounting reliability. Another main approach focuses on soft magnetic composite material formulations, powder particle size distribution, insulation coating, and resin systems to improve permeability, insulation, and high-frequency low-loss performance. The development direction of the core soft magnetic composite material for molded inductors has focused on balancing high saturation magnetic induction, high-frequency low loss, low eddy current loss, and low dielectric loss.

[0002] However, existing technologies still have at least the following shortcomings. First, conventional lateral leads or long lead paths result in high DC resistance and increase additional losses at high frequencies. Second, conventional surface-mount multilayer electrode structures introduce contact resistance and high-frequency losses at multiple interfaces between the conductor, plating, and solder. Third, traditional amorphous and alloy powder composite systems may still experience a decrease in Q-value at high frequencies due to insufficient resistivity, high dielectric constant, and large eddy current paths. Fourth, if the dielectric constant of the resin phase is too high, or if the insulation and pore structure design of the powder coating layer are insufficient, high-frequency losses are still difficult to effectively suppress. [Summary of the Invention] To overcome the above problems, this invention proposes a low-loss integrally molded inductor and its preparation method that can effectively solve the above problems.

[0003] The present invention provides a technical solution to solve the above-mentioned technical problems by providing a low-loss integrally molded inductor, comprising a magnet and a winding; the winding is a straight structure parallel to the width direction of the magnet, at least a portion of the winding is embedded inside the magnet, and both ends of the winding are led out from the opposite surface of the magnet to form protruding structures, the protrusion height of the protruding structures is 0.1-0.5 mm, the protruding portion of the protruding structures is trapezoidal, and the angle of the hypotenuse of the trapezoidal structure is 45°-85°; the magnet is formed by pressing and curing a soft magnetic composite material, the soft magnetic composite material comprising Fe-based nanocrystalline powder, alloy powder and composite resin, wherein the Fe-based nanocrystalline alloy in the Fe-based nanocrystalline powder comprises, by mass percentage: Fe 72.0%-81.5%, Co 12.3%-18.0%, Si 2.5%-4.0%, B 3.0%-4.5%, P 0.5%-1.5%, C 0.2%-0.5%, and the total of all components is 100%. Preferably, the Fe-based nanocrystalline powder has a particle size of 10–25 μm, and the surface of the Fe-based nanocrystalline powder is coated with a mesoporous oxide with a particle size of 10–50 nm.

[0004] Preferably, the mesoporous oxide is one or both of mesoporous silicon dioxide and mesoporous manganese dioxide.

[0005] Preferably, the alloy powder is one or two of carbonyl iron, FeSi, FeSiCr, and FeNi, the particle size of the alloy powder is 0.6 to 5 μm, and the surface of the alloy powder is coated with mesoporous oxide.

[0006] Preferably, in the metallic magnetic powder phase of the soft magnetic composite material, the Fe-based nanocrystalline powder accounts for 47.5% to 79.5%, and the alloy powder accounts for 19.5% to 47.5%.

[0007] Preferably, the composite resin comprises polyphenylene ether, polytetrafluoroethylene and epoxy resin, wherein the total weight of polyphenylene ether and polytetrafluoroethylene accounts for 60% to 80% of the composite resin, the epoxy resin accounts for 20% to 40% of the composite resin, and the composite resin accounts for 1% to 5% of the total weight of the mixed powder of metal magnetic powder and resin.

[0008] Preferably, the winding is a copper conductor winding, and the protruding structure forms a welding electrode through surface solder to reduce the interface of multiple metal electrodes.

[0009] Preferably, the low-loss integrally molded inductor has dimensions of 5 mm × 2 mm × 1.5 mm, a winding thickness of 0.5 mm, a coil width of 1.0 mm, and 0.5 turns.

[0010] This invention also provides a method for fabricating a low-loss integrally molded inductor, comprising the following steps: The metal bulk is melted and then atomized and cooled to form Fe-based nanocrystalline powder and / or alloy powder. The Fe-based nanocrystalline powder and the alloy powder are respectively mixed with mesoporous oxide, composite resin and solvent, and then ball-milled or kneaded to form a coating layer, and dried to form a mixed powder; The mixed powder and pre-made winding are placed into a mold and pressed to form a semi-finished product; The semi-finished product was baked at 200°C for 4 hours in a nitrogen atmosphere to complete the curing process; The winding leads are surface soldered to form welding electrodes.

[0011] Preferably, the Fe-based nanocrystalline powder and the alloy powder are coated separately and then mixed; the mold is reserved with molding space for the lead-out ends of the winding to form a protruding structure, so that the lead-out end height after curing is 0.1 to 0.5 mm and the bevel angle is 45° to 85°.

[0012] Compared with existing technologies, the low-loss integrally molded inductor and its preparation method of the present invention can shorten the conductor path, reduce DCR, and reduce the eddy current sensitive area between the conductor and the magnet by straightening the winding, leading out at the top and bottom, and designing a prominent trapezoidal welding end; by compounding Fe, Co, Si, B, P, and C nanocrystalline powders with alloy powders, it can achieve a balance between high saturation magnetic induction intensity, low high-frequency loss, and better piezoelectric behavior; by using mesoporous oxide coating and a low-dielectric composite resin system, it can reduce dielectric loss and improve high-frequency insulation effect. [Attached Image Description] Figure 1 This is a first cross-sectional view of the low-loss integrally molded inductor of the present invention; Figure 2 This is a second cross-sectional view of the low-loss integrally molded inductor of the present invention; Figure 3 This is a flowchart of the low-loss integral molding inductor fabrication method of the present invention.

Detailed Implementation Methods

[0013] It should be noted that in the embodiments of the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are limited to relative positions on the specified view, rather than absolute positions.

[0014] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0015] Please see Figures 1 to 3 The low-loss integrally molded inductor of the present invention includes a magnet 1 and a winding 2. The winding 2 has a straight structure, parallel to the width direction of the magnet 1, and extends beyond the magnet 1 as a protruding structure with a protrusion height of 0.1~0.5mm. The protruding portion has a trapezoidal structure, with the hypotenuse angle of the trapezoid being 45°~85°, which facilitates soldering of the circuit, increases the contact area, and improves soldering strength. The magnet 1 is composed of Fe-based nanocrystals, and its composition is a composite material of powder and alloy powder containing 72.0wt%~81.5wt% Fe, 12.3wt%~18.0wt% Co, 2.5wt%~4.0wt% Si, 3.0wt%~4.5wt% B, 0.5wt%~1.5wt% P, and 0.2wt%~0.5wt% C. The nanocrystals are coated with mesoporous oxides such as mesoporous silica and mesoporous manganese dioxide. The nanocrystal powder particles have a particle size of 10-25 μm, and the mesoporous oxide particles have a particle size of 10-50 nm. The nanocrystals account for 47.5%-79.5% of the weight of the composite material. The alloy powder is one or two of carbonyl iron, FeSi, FeSiCr, and FeNi. The alloy powder is coated with mesoporous oxides such as mesoporous silica and mesoporous manganese dioxide. The alloy powder particles have a particle size of 0.6-5 μm, and the mesoporous oxide particles have a particle size of 10-50 nm. The alloy powder accounts for 19.5%-47.5% of the weight of the composite material. The composite material contains a composite resin of polyphenylene ether, polytetrafluoroethylene, and epoxy resin. Polyphenylene ether and polytetrafluoroethylene account for 60%-80% of the weight of the mixed resin, epoxy resin accounts for 20%-40% of the weight of the mixed resin, and the resin accounts for 1%-5% of the weight of the mixed powder. The sample dimensions were 5mm*2mm*1.5mm, winding thickness 0.5mm, coil width 1.0mm, and 0.5 turns. The L and Q values ​​of the inductance were tested using a WK6500B at 20MHz and 1V. The inductance loss was tested using a SY8218 at a test frequency of 10MHz and a applied current of 0.5A.

[0016] The present invention will be further described below with reference to specific embodiments and comparative examples.

[0017] Example 1: A low-loss integrally molded inductor comprises a magnet 1 and a winding 2. The winding 2 has a straight structure and is parallel to the width direction of the magnet 1. The winding 2 extends out of the magnet 1 as a protruding structure with a protrusion height of 0.1 mm. The protruding part has a trapezoidal structure with a 45° hypotenuse angle, which facilitates soldering of circuits, increases the contact area, and improves soldering strength.

[0018] Magnet 1 is composed of Fe-based nanocrystals, and its composition is a composite material of powder and alloy powder of 81.5wt%Fe, 12.3wt%Co, 2.5wt%Si, 3.0wt%B, 0.5wt%P, and 0.2wt%C.

[0019] The composite material comprises nanocrystalline powder coated with mesoporous silica with a dielectric constant of 1.9, nanocrystalline powder particles with a particle size of 10 μm, and mesoporous oxide particles with a particle size of 10 nm. Nanocrystalline powder accounts for 79.5% of the composite material by weight. The alloy powder is a mixture of carbonyl iron and FeNi, also coated with mesoporous silica with a dielectric constant of 1.9. The carbonyl iron alloy powder particles have a particle size of 5 μm, the FeNi powder particles have a particle size of 1 μm, and the mesoporous oxide particles have a particle size of 10 nm. Carbonyl iron accounts for 11.5% of the composite material by weight, and FeNi accounts for 8% of the mixed powder by weight. The composite material also includes a composite resin of polyphenylene ether, polytetrafluoroethylene, and epoxy resin. Polyphenylene ether accounts for 30% of the mixed resin by weight, polytetrafluoroethylene accounts for 30% of the mixed resin by weight, and epoxy resin accounts for 40% of the mixed resin by weight. The mixed resin has a dielectric constant of 2.9 and accounts for 5% of the mixed powder by weight.

[0020] The sample dimensions were 5mm*2mm*1.5mm, winding thickness 0.5mm, coil width 1.0mm, and 0.5 turns. The L and Q values ​​of the inductance were tested using a WK6500B at 20MHz and 1V. The inductance loss was tested using a SY8218 at a test frequency of 10MHz and a applied current of 0.5A.

[0021] Example 2: A low-loss integrally molded inductor comprises a magnet 1 and a winding 2. The winding 2 has a straight structure and is parallel to the width direction of the magnet 1. The winding 2 extends out of the magnet 1 as a protruding structure with a protrusion height of 0.5mm. The protruding part has a trapezoidal structure with a hypotenuse angle of 85°, which facilitates soldering of circuits, increases the contact area, and improves soldering strength.

[0022] Magnet 1 is composed of Fe-based nanocrystals, and its composition is a composite material of powder and alloy powder of 72.0 wt% Fe, 18.0 wt% Co, 4.0 wt% Si, 4.5 wt% B, 1.5 wt% P, and 0.5 wt% C.

[0023] The composite material comprises nanocrystalline powder coated with mesoporous manganese dioxide with a dielectric constant of 2.7, nanocrystalline powder particles with a particle size of 25 μm, and mesoporous oxide particles with a particle size of 50 nm. The nanocrystalline powder accounts for 47.5% of the weight of the composite material. The alloy powder is FeSiCr, coated with mesoporous manganese dioxide with a dielectric constant of 2.7, alloy powder particles with a particle size of 3 μm, and mesoporous oxide particles with a particle size of 50 nm. The alloy powder accounts for 47.5% of the weight of the composite material. The composite material contains a composite resin of polyphenylene ether, polytetrafluoroethylene, and epoxy resin. Polyphenylene ether accounts for 35% of the weight of the mixed resin, polytetrafluoroethylene accounts for 45% of the weight of the mixed resin, and epoxy resin accounts for 20% of the weight of the mixed resin. The dielectric constant of the mixed resin is 2.5, and the resin accounts for 1% of the weight of the mixed powder.

[0024] The sample dimensions were 5mm*2mm*1.5mm, winding thickness 0.5mm, coil width 1.0mm, and 0.5 turns. The L and Q values ​​of the inductance were tested using a WK6500B at 20MHz and 1V. The inductance loss was tested using a SY8218 at a test frequency of 10MHz and a applied current of 0.5A.

[0025] Example 3: A low-loss integrally molded inductor comprises a magnet 1 and a winding 2. The winding 2 has a straight structure and is parallel to the width direction of the magnet 1. The winding 2 extends out of the magnet 1 as a protruding structure with a protrusion height of 0.3mm. The protruding part has a trapezoidal structure with a hypotenuse angle of 65°, which facilitates soldering of circuits, increases the contact area, and improves soldering strength.

[0026] Magnet 1 is composed of Fe-based nanocrystals, and its composition is a composite material of powder and alloy powder containing 75.9wt%Fe, 15.6wt%Co, 2.9wt%Si, 4.0wt%B, 1.2wt%P, and 0.4wt%C.

[0027] The composite material comprises nanocrystalline powder coated with mesoporous silica with a dielectric constant of 1.5, nanocrystalline powder particles with a particle size of 15 μm, mesoporous oxide particles with a particle size of 18 nm, and nanocrystalline powder accounting for 65% of the composite material by weight. The alloy powder is FeSi, coated with mesoporous manganese dioxide with a dielectric constant of 2.7, alloy powder particles with a particle size of 1.5 μm, mesoporous oxide particles with a particle size of 15 nm, and alloy powder accounting for 35% of the composite material by weight. The composite material also includes a composite resin of polyphenylene ether, polytetrafluoroethylene (PTFE), and epoxy resin, with polyphenylene ether accounting for 32% of the mixed resin by weight, PTFE accounting for 38% of the mixed resin by weight, and epoxy resin accounting for 30% of the mixed resin by weight. The mixed resin has a dielectric constant of 2.6 and the resin accounts for 2.0% of the mixed powder by weight.

[0028] The sample dimensions were 5mm*2mm*1.5mm, winding thickness 0.5mm, coil width 1.0mm, and 0.5 turns. The L and Q values ​​of the inductance were tested using a WK6500B at 20MHz and 1V. The inductance loss was tested using a SY8218 at a test frequency of 10MHz and a applied current of 0.5A.

[0029] Comparative Example 1: A low-loss integrally molded inductor comprises a magnet 1 and a winding 2. The winding 2 has a straight structure, parallel to the width direction of the magnet 1, and is parallel to the magnet 1. Electrode layers of Cu, Ni, and Sn are formed on the surface of the winding 2. The magnet 1 is composed of Fe-based nanocrystals, specifically a composite material of powder and alloy powder containing 81.5 wt% Fe, 12.3 wt% Co, 2.5 wt% Si, 3.0 wt% B, 0.5 wt% P, and 0.2 wt% C.

[0030] The composite material comprises nanocrystalline powder coated with mesoporous silica with a dielectric constant of 1.9, nanocrystalline powder particles with a particle size of 10 μm, and mesoporous oxide particles with a particle size of 10 nm. Nanocrystalline powder accounts for 79.5% of the composite material by weight. The alloy powder is a mixture of carbonyl iron and FeNi, also coated with mesoporous silica with a dielectric constant of 1.9. The carbonyl iron alloy powder particles have a particle size of 5 μm, the FeNi powder particles have a particle size of 1 μm, and the mesoporous oxide particles have a particle size of 10 nm. Carbonyl iron accounts for 11.5% of the composite material by weight, and FeNi accounts for 8% of the mixed powder by weight. The composite material also includes a composite resin of polyphenylene ether, polytetrafluoroethylene, and epoxy resin. Polyphenylene ether accounts for 30% of the mixed resin by weight, polytetrafluoroethylene accounts for 30% of the mixed resin by weight, and epoxy resin accounts for 40% of the mixed resin by weight. The mixed resin has a dielectric constant of 2.9 and accounts for 5% of the mixed powder by weight.

[0031] The sample dimensions were 5mm*2mm*1.5mm, winding thickness 0.5mm, coil width 1.0mm, and 0.5 turns. The L and Q values ​​of the inductance were tested using a WK6500B at 20MHz and 1V. The inductance loss was tested using a SY8218 at a test frequency of 10MHz and a applied current of 0.5A.

[0032] Comparative Example 2: A low-loss integrally molded inductor comprises a magnet 1 and a winding 2. The winding 2 has a straight structure and is parallel to the width direction of the magnet 1. The winding 2 extends out of the magnet as a protruding structure with a protrusion height of 0.1 mm. The protruding part has a trapezoidal structure with a hypotenuse angle of 45°, which facilitates soldering of circuits, increases the contact area, and improves soldering strength.

[0033] Magnet 1 is composed of Fe-based nanocrystals, and its composition is a composite material of powder and alloy powder of 81.5wt%Fe, 12.3wt%Co, 2.5wt%Si, 3.0wt%B, 0.5wt%P, and 0.2wt%C. The composite material comprises nanocrystalline powder coated with silicon dioxide, with a dielectric constant of 3.9. The nanocrystalline powder particles are 10 μm in size, and the oxide particles are 10 nm in diameter. The nanocrystalline powder accounts for 79.5% of the weight of the composite material. The alloy powder is a mixture of carbonyl iron and FeNi, with the same surface coated with silicon dioxide and a dielectric constant of 3.9. The carbonyl iron alloy powder particles are 5 μm in size, and the FeNi powder particles are 1 μm in size. The oxide particles are 10 nm in diameter. The carbonyl iron accounts for 11.5% of the weight of the composite material, and the FeNi accounts for 8% of the weight of the mixed powder. The composite material also includes a composite resin of polyphenylene ether, polytetrafluoroethylene, and epoxy resin. Polyphenylene ether accounts for 30% of the weight of the mixed resin, polytetrafluoroethylene accounts for 30% of the weight of the mixed resin, and epoxy resin accounts for 40% of the weight of the mixed resin. The mixed resin has a dielectric constant of 2.9 and accounts for 5% of the weight of the mixed powder.

[0034] The sample dimensions were 5mm*2mm*1.5mm, winding thickness 0.5mm, coil width 1.0mm, and 0.5 turns. The L and Q values ​​of the inductance were tested using a WK6500B at 20MHz and 1V. The inductance loss was tested using a SY8218 at a test frequency of 10MHz and a applied current of 0.5A.

[0035] Comparative Example 3: A low-loss integrally molded inductor comprises a magnet 1 and a winding 2. The winding 2 has a straight structure and is parallel to the width direction of the magnet 1. The winding 2 extends out of the magnet 1 as a protruding structure with a protrusion height of 0.1 mm. The protruding part has a trapezoidal structure with a 45° hypotenuse angle, which facilitates soldering of circuits, increases the contact area, and improves soldering strength.

[0036] Magnet 1 is composed of Fe-based nanocrystals, and its composition is a composite material of powder and alloy powder of 81.5wt%Fe, 12.3wt%Co, 2.5wt%Si, 3.0wt%B, 0.5wt%P, and 0.2wt%C. The composite material contains nanocrystalline powder coated with mesoporous silica with a dielectric constant of 1.9. The nanocrystalline powder particles are 10 μm in size, and the mesoporous oxide particles are 10 nm in diameter. The nanocrystalline powder accounts for 79.5% of the weight of the composite material. The alloy powder is a mixture of carbonyl iron and FeNi. The alloy powder is coated with mesoporous silica with a dielectric constant of 1.9. The carbonyl iron alloy powder particles are 5 μm in size, and the FeNi powder particles are 1 μm in size. The mesoporous oxide particles are 10 nm in diameter. The carbonyl iron accounts for 11.5% of the weight of the composite material, and the FeNi accounts for 8% of the weight of the mixed powder. The composite material contains epoxy resin with a dielectric constant of 4.1, and the resin accounts for 5% of the weight of the mixed powder.

[0037] The sample dimensions were 5mm*2mm*1.5mm, winding thickness 0.5mm, coil width 1.0mm, and 0.5 turns. The L and Q values ​​of the inductance were tested using a WK6500B at 20MHz and 1V. The inductance loss was tested using a SY8218 at a test frequency of 10MHz and a applied current of 0.5A.

[0038] Comparative Example 4: A low-loss integrally molded inductor includes a magnet 1 and a winding 2. The winding 2 has a straight structure and is perpendicular to the width direction of the magnet 1. The magnet 1 is composed of Fe-based nanocrystals, and its composition is a composite material of powder and alloy powder containing 81.5wt%Fe, 12.3wt%Co, 2.5wt%Si, 3.0wt%B, 0.5wt%P, and 0.2wt%C.

[0039] The composite material comprises nanocrystalline powder coated with mesoporous silica with a dielectric constant of 1.9, nanocrystalline powder particles with a particle size of 10 μm, and mesoporous oxide particles with a particle size of 10 nm. Nanocrystalline powder accounts for 79.5% of the composite material by weight. The alloy powder is a mixture of carbonyl iron and FeNi, also coated with mesoporous silica with a dielectric constant of 1.9. The carbonyl iron alloy powder particles have a particle size of 5 μm, the FeNi powder particles have a particle size of 1 μm, and the mesoporous oxide particles have a particle size of 10 nm. Carbonyl iron accounts for 11.5% of the composite material by weight, and FeNi accounts for 8% of the mixed powder by weight. The composite material also includes a composite resin of polyphenylene ether, polytetrafluoroethylene, and epoxy resin. Polyphenylene ether accounts for 30% of the mixed resin by weight, polytetrafluoroethylene accounts for 30% of the mixed resin by weight, and epoxy resin accounts for 40% of the mixed resin by weight. The mixed resin has a dielectric constant of 2.9 and accounts for 5% of the mixed powder by weight.

[0040] The sample dimensions were 5mm*2mm*1.5mm, winding thickness 0.5mm, coil width 1.0mm, and 0.5 turns. The L and Q values ​​of the inductance were tested using a WK6500B at 20MHz and 1V. The inductance loss was tested using a SY8218 at a test frequency of 10MHz and a applied current of 0.5A. Comparative Example 5: A low-loss integrally molded inductor comprises a magnet 1 and a winding 2. The winding 2 has a straight structure and is parallel to the width direction of the magnet 1. The winding 2 extends out of the magnet as a protruding structure with a protrusion height of 0.1 mm. The protruding part has a trapezoidal structure with a hypotenuse angle of 45°, which facilitates soldering of circuits, increases the contact area, and improves soldering strength.

[0041] Magnet 1 is composed of Fe-based nanocrystals, with a composition of 81.5 wt% Fe, 12.3 wt% Co, 2.5 wt% Si, 3.0 wt% B, 0.5 wt% P, and 0.2 wt% C powder. The nanocrystals are coated with mesoporous silica with a dielectric constant of 1.9. The nanocrystal powder particles have a size of 10 μm, and the mesoporous oxide particles have a size of 10 nm. The composite material consists of a composite resin of polyphenylene ether, polytetrafluoroethylene, and epoxy resin. Polyphenylene ether accounts for 30% of the weight of the mixed resin, polytetrafluoroethylene accounts for 30% of the weight of the mixed resin, and epoxy resin accounts for 40% of the weight of the mixed resin. The dielectric constant of the mixed resin is 2.9, and the resin accounts for 5% of the weight of the mixed powder.

[0042] The sample dimensions were 5mm*2mm*1.5mm, winding thickness 0.5mm, coil width 1.0mm, and 0.5 turns. The L and Q values ​​of the inductance were tested using a WK6500B at 20MHz and 1V. The inductance loss was tested using a SY8218 at a test frequency of 10MHz and a applied current of 0.5A.

[0043] Comparative Example 6: A low-loss integrally molded inductor comprises a magnet 1 and a winding 2. The winding 2 has a straight structure and is parallel to the width direction of the magnet 1. The winding 2 extends out of the magnet 1 as a protruding structure with a protrusion height of 0.1 mm. The protruding part has a trapezoidal structure with a 45° hypotenuse angle, which facilitates soldering of circuits, increases the contact area, and improves soldering strength.

[0044] Magnet 1 is composed of Fe-based nanocrystals, specifically a composite material of powders and alloy powders comprising 81.5 wt% Fe, 12.3 wt% Co, 2.5 wt% Si, 3.0 wt% B, 0.5 wt% P, and 0.2 wt% C. The nanocrystal powder has a particle size of 10 μm, accounting for 79.5% of the composite material by weight. The alloy powder is a mixture of carbonyl iron and FeNi, with the carbonyl alloy powder having a particle size of 5 μm and the FeNi powder having a particle size of 1 μm. The mesoporous oxide has a particle size of 10 nm. Carbonyl iron accounts for 11.5% of the composite material by weight, and FeNi accounts for 8% of the mixed powder by weight. The composite material contains a composite resin of polyphenylene ether, polytetrafluoroethylene, and epoxy resin, with polyphenylene ether, polytetrafluoroethylene, and epoxy resin each accounting for 30% and 40% of the mixed resin by weight. The dielectric constant of the mixed resin is 2.9, and the resin itself accounts for 5% of the mixed powder by weight.

[0045] The sample dimensions were 5mm*2mm*1.5mm, winding thickness 0.5mm, coil width 1.0mm, and 0.5 turns. The L and Q values ​​of the inductance were tested using a WK6500B at 20MHz and 1V. The inductance loss was tested using a SY8218 at a test frequency of 10MHz and a applied current of 0.5A.

[0046] Table 1. Performance Comparison of Examples and Comparative Examples

[0047] Compared with the embodiment and the comparative example, it can be seen that when the inductance values ​​are similar, the Q of the embodiment is higher than that of the comparative example. This shows that the control of the component and the design of the assembly structure are very important for achieving low Q value and high loss at high frequency while meeting the inductance requirements.

[0048] First, the embodiments significantly improve the high-frequency Q value and reduce losses while maintaining the target inductance value essentially unchanged. The inductance values ​​of embodiments 1 to 3 are all 50–51 nH, and the Q values ​​reach 65–69 at 20 MHz, while the comparative examples are only 26–55. Simultaneously, the inductance losses of the embodiments are only 1.23–1.33 mW, significantly lower than the 1.76–2.67 mW of the comparative examples. This indicates that the present invention does not sacrifice inductance value for local performance improvement, but rather achieves both high Q value and low loss under similar inductance value conditions.

[0049] Secondly, the structural design of this embodiment effectively reduces DC resistance and improves high-frequency characteristics. Compared with Comparative Example 4, this embodiment adopts a straight structure with winding 2 parallel to the width direction of magnet 1, and shortens the conductor path and reduces the eddy current area between the copper wire and the magnet through the design of upper and lower leads and protruding ends. Therefore, the DCR is reduced from 0.38 mΩ to 0.15-0.16 mΩ, the Q value at 20 MHz is increased from 26 to 65-69, and the loss at 10 MHz and 0.5 A is reduced from 2.67 mW to 1.23-1.33 mW, showing significant advantages. Compared with Comparative Example 1, this embodiment eliminates the surface Cu / Ni / Sn multilayer electrode interface and replaces it with direct soldering of protruding leads to form welding electrodes, which further reduces high-frequency contact loss, increasing the Q value at 20 MHz from 46 to 65-69 and reducing the loss from 1.87 mW to 1.23-1.33 mW.

[0050] Third, the mesoporous oxide coating design in the embodiments is beneficial for reducing high-frequency dielectric losses. Compared with Comparative Example 2, the embodiments use mesoporous silica or mesoporous manganese dioxide as the coating layer, instead of ordinary silica. At 20 MHz, the Q value increased from 41 to 65-69, and the loss decreased from 2.03 mW to 1.23-1.33 mW. Compared with Comparative Example 6, under similar conditions, the embodiments, after adding a mesoporous oxide coating layer, saw the Q value increase from 55 to 65-69 at 20 MHz, and the loss decrease from 1.76 mW to 1.23-1.33 mW. This demonstrates that the mesoporous coating layer plays an important role in improving insulation performance and suppressing high-frequency losses.

[0051] Fourth, the low-dielectric composite resin system of the embodiments can further improve high-frequency performance. Compared with Comparative Example 3, the embodiments use a composite resin composed of polyphenylene ether, polytetrafluoroethylene, and epoxy resin, instead of a single epoxy resin. At 20MHz, the Q value increased from 41 to 65-69, and the loss decreased from 2.01 mW to 1.23-1.33 mW. This shows that the low-dielectric-constant resin system helps to reduce the dielectric loss of the material system under high-frequency conditions, thereby improving the quality factor.

[0052] Fifth, the embodiments employ a magnetic system combining Fe-based nanocrystalline powder and alloy powder, which can balance inductance, high-frequency Q value, and low loss. Compared with Comparative Example 5, which uses only Fe-based nanocrystalline powder, the embodiments show an increase in Q value from 34 to 65-69 at 20 MHz, a decrease in inductance loss from 2.34 mW to 1.23-1.33 mW, and a decrease in DCR from 0.17 mΩ to 0.15-0.16 mΩ. This demonstrates that the composite magnetic powder system is significantly superior to the single powder system in terms of high-frequency magnetic performance and loss control.

[0053] Sixth, although there are variations in the height, trapezoidal angle, nanocrystal ratio, coating type and resin ratio in Examples 1 to 3, they all consistently achieve high Q values, low DCR and low losses, indicating that the present invention has good applicability and repeatability. It does not rely on a single demanding parameter point to achieve performance improvement, but rather achieves a stable high-frequency low-loss effect through the synergistic effect of structural design and material design.

[0054] This invention significantly improves the Q value of the inductor under high-frequency conditions and reduces losses by synergistically optimizing the device structure and material system of the integrally molded inductor while maintaining the target inductance value essentially unchanged. Compared with the comparative example, this invention adopts a straight structure with the winding 2 parallel to the width direction of the magnet 1 and a structure with top and bottom leads and protruding ends, which can shorten the copper wire conduction path, reduce DC resistance, and reduce the eddy current interaction area between the copper wire and the magnet, while reducing the high-frequency contact loss caused by the traditional multilayer electrode interface; the use of mesoporous oxide to coat the surface of the magnetic powder, combined with a low-dielectric composite resin system composed of polyphenylene ether, polytetrafluoroethylene and epoxy resin, can effectively reduce the high-frequency dielectric loss of the material system; the use of a composite magnetic powder system of Fe-based nanocrystalline powder and alloy powder can balance inductance value, Q value and loss control. Experimental results show that the Q value of the embodiments of the present invention reaches 65-69 at 20 MHz, which is significantly better than the 26-55 of the comparative example. Moreover, the inductance loss under the conditions of 10 MHz and 0.5 A is only 1.23-1.33 mW, which is significantly lower than the 1.76-2.67 mW of the comparative example. This indicates that the present invention can effectively meet the application requirements of low loss, high Q value and miniaturization of high frequency power devices.

[0055] The present invention discloses a method for fabricating a low-loss integrally molded inductor. The fabrication process involves melting a metal block and then cooling it through atomization to form powder. The atomized nanocrystals and alloy powder are then mixed with mesoporous oxide, resin, and solvent, respectively, and mixed using a ball mill or kneader to form a coating layer. This mixture is then dried to form a mixed powder. The mixed powder and electrodes are implanted into a mold of a fixed shape and pressed to form a semi-finished product. This semi-finished product is then baked in a nitrogen oven at 200°C for 4 hours to form a cured inductor. Finally, surface soldering is used to form welding electrodes. The final inductor sample has dimensions of 5mm*2mm*1.5mm, a winding thickness of 0.5mm, a coil width of 1.0mm, and 0.5 turns. The L and Q values ​​of the inductor are tested using a WK6500B at 20MHz and 1V. The inductor loss is tested using a SY8218 at a test frequency of 10MHz and a loaded current of 0.5A.

[0056] Compared with existing technologies, the low-loss integrally molded inductor and its fabrication method of the present invention, through the design of material composition and device structure, reduces the length of copper wires by using a structure with leads on the top and bottom of the chip, thereby reducing the DC resistance of the copper wires. At the same time, the straight structure reduces the eddy current area between the copper wires and the material, improving the high-frequency inductance value. In addition, the protruding structure of the lead surface reduces the multi-layer interface of the electrodes, which is only achieved by the copper wire solder structure, reducing the high-frequency loss caused by the high contact resistance of the multi-section interface. Furthermore, the high-frequency low-loss is achieved by adjusting the saturation magnetization of Fe-based nanocrystals with Co and controlling the grain size with P and C. The high-frequency loss of the material is further reduced by lowering the dielectric constant of the coating material, thereby meeting the application requirements for high-frequency low-loss power devices.

[0057] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any modifications, equivalent substitutions and improvements made within the concept of the present invention should be included within the patent protection scope of the present invention.

Claims

1. A low-loss integrally molded inductor, characterized in that, It includes a magnet and a winding; the winding is a straight structure parallel to the width direction of the magnet, at least a portion of the winding is embedded inside the magnet, and both ends of the winding are led out from the opposite surface of the magnet to form a protruding structure. The protruding height of the protruding structure is 0.1 to 0.5 mm, and the protruding part of the protruding structure is trapezoidal with a hypotenuse angle of 45° to 85°. The magnet is formed by pressing and curing a soft magnetic composite material, which includes Fe-based nanocrystalline powder, alloy powder, and composite resin. The Fe-based nanocrystalline alloy in the Fe-based nanocrystalline powder comprises, by mass percentage: Fe 72.0%–81.5%, Co 12.3%–18.0%, Si 2.5%–4.0%, B 3.0%–4.5%, P 0.5%–1.5%, and C 0.2%–0.5%, and the total of all components is 100%.

2. The low-loss integrally molded inductor as described in claim 1, characterized in that, The Fe-based nanocrystalline powder has a particle size of 10–25 μm, and the surface of the Fe-based nanocrystalline powder is coated with mesoporous oxide, the particle size of which is 10–50 nm.

3. The low-loss integrally molded inductor as described in claim 2, characterized in that, The mesoporous oxide is one or both of mesoporous silicon dioxide and mesoporous manganese dioxide.

4. The low-loss integrally molded inductor as described in claim 1, characterized in that, The alloy powder is one or two of carbonyl iron, FeSi, FeSiCr, and FeNi. The particle size of the alloy powder is 0.6 to 5 μm, and the surface of the alloy powder is coated with mesoporous oxide.

5. The low-loss integrally molded inductor as described in claim 1 or 4, characterized in that, In the metallic magnetic powder phase of the soft magnetic composite material, the Fe-based nanocrystalline powder accounts for 47.5% to 79.5%, and the alloy powder accounts for 19.5% to 47.5%.

6. The low-loss integrally molded inductor as described in claim 1, characterized in that, The composite resin includes polyphenylene ether, polytetrafluoroethylene and epoxy resin, wherein polyphenylene ether and polytetrafluoroethylene together account for 60% to 80% of the weight of the composite resin, epoxy resin accounts for 20% to 40% of the weight of the composite resin, and the composite resin accounts for 1% to 5% of the total weight of the mixed powder of metal magnetic powder and resin.

7. The low-loss integrally molded inductor as described in claim 1, characterized in that, The winding is a copper conductor winding, and the protruding structure forms welding electrodes through surface solder to reduce the interface of multi-layer metal electrodes.

8. The low-loss integrally molded inductor as described in claim 1, characterized in that, The low-loss integral molded inductor has dimensions of 5 mm × 2 mm × 1.5 mm, a winding thickness of 0.5 mm, a coil width of 1.0 mm, and 0.5 turns.

9. A method for fabricating a low-loss integrally molded inductor as described in any one of claims 1-8, characterized in that, Includes the following steps: The metal bulk is melted and then atomized and cooled to form Fe-based nanocrystalline powder and / or alloy powder. The Fe-based nanocrystalline powder and the alloy powder are respectively mixed with mesoporous oxide, composite resin and solvent, and then ball-milled or kneaded to form a coating layer, and dried to form a mixed powder; The mixed powder and pre-made winding are placed into a mold and pressed to form a semi-finished product; The semi-finished product was baked at 200°C for 4 hours in a nitrogen atmosphere to complete the curing process; The winding leads are surface soldered to form welding electrodes.

10. The low-loss integrally molded inductor and its preparation method as described in claim 9, characterized in that, The Fe-based nanocrystalline powder and the alloy powder are coated and then mixed. A molding space is reserved in the mold for the lead-out ends of the winding to form a protruding structure, so that the lead-out end height is 0.1 to 0.5 mm and the bevel angle is 45° to 85° after curing.

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