Inductor based on low-voltage plastic package molding and preparation method thereof

Abstract

The invention discloses an inductor based on low-voltage plastic package forming and a preparation method thereof, and relates to the technical field of metal soft magnetic composite material preparation. The method comprises the following steps: preparing iron-based alloy magnetic powder by adopting a gas atomization method; the prepared iron-based alloy magnetic powder is subjected to double-layer coating, and iron-based alloy coated powder particles are obtained; sintering to prepare a magnetic core, and winding the magnetic core; and putting the iron-based alloy coated powder particles into the wound magnetic core, and carrying out low-pressure plastic package molding to obtain the prepared inductor. According to the manufacturing method, the integrally-formed inductor is obtained through the low-voltage plastic packaging forming technology, the manufactured inductor has good comprehensive electromagnetic performance and high reliability, and the requirement for the miniaturization and modularization development direction of inductance devices can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of metal soft magnetic composite materials, and in particular to an inductor based on low-voltage plastic packaging and a preparation method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Inductors are one of the three essential basic components in electronic circuits. They mainly play the role of filtering, oscillation, delay, and trapping. They also have the functions of screening signals, filtering noise, stabilizing current, and suppressing electromagnetic interference. In recent years, with the widespread application of technologies such as AI (artificial intelligence), IoT (Internet of Things), 5G / 6G communications, and ADAS (advanced driver assistance systems), all electromagnetic devices require more complex and higher-precision control, which has prompted inductors to continue to develop in the direction of miniaturization, high frequency, high power, and modularization.

[0004] According to different preparation processes, the commonly used inductor categories currently include: winding type, laminated type, integrated molded and thin film inductors. However, the above inductors all have different degrees of preparation or performance defects. Among them, for winding inductors, their molding internal stress is large, the comprehensive soft magnetic properties are relatively poor, and they have the disadvantage of poor shielding effect; for laminated inductors and thin film inductors, they are formed by slurry casting and lamination, and the magnetic phase solid content is 40%-60%, which is difficult to maximize the electromagnetic properties of magnetic powder materials; for conventional one-piece molded inductors, they are generally prepared by high-voltage (about 650MPa) molding, which can easily cause the coil to deform and cause fatal short-circuit problems. Special copper wires with thickened paint films are required, and there is a great risk of product reliability. In addition, the internal stress is difficult to eliminate, resulting in excessive inductance loss and low temperature rise current.

[0005] Therefore, how to achieve low-loss and high-performance preparation of miniaturized inductors has become a technical problem that needs to be urgently solved in existing technologies. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide an inductor based on low-voltage plastic packaging molding and a preparation method thereof. Compared with the high-voltage (about 650MPa) molding process of conventional integrated inductors, the present invention adopts a low-voltage plastic packaging molding process to obtain an integrated molded inductor, and the prepared inductor has good comprehensive electromagnetic properties and very high reliability, which can meet the development requirements of miniaturization and modularization of inductor devices.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] A first aspect of the present invention provides a method for preparing an inductor based on low-voltage plastic packaging, comprising the following steps:

[0009] The iron-based alloy magnetic powder is prepared by gas atomization method;

[0010] Double-coating the prepared iron-based alloy magnetic powder to obtain iron-based alloy coated powder particles;

[0011] Sintering to prepare a magnetic core, and winding the magnetic core;

[0012] The iron-based alloy coated powder particles are placed in the wound magnetic core for low-voltage plastic sealing to obtain the prepared inductor.

[0013] Furthermore, the specific steps of preparing iron-based alloy magnetic powder by gas atomization are:

[0014] The master alloy raw materials are first melted under high temperature conditions to form molten steel, and then the molten steel is sprayed out through the leakage holes of the spray plate under the action of gravity and pressure, and is dispersed by high-pressure nitrogen to form iron-based alloy magnetic powder in the cooling tower.

[0015] Furthermore, the particle size range of the iron-based alloy magnetic powder is 6 μm to 110 μm.

[0016] Furthermore, the composition of the iron-based alloy magnetic powder is: Fe: 79.6wt%, Nb: 4.0wt%, Si: 5.9wt%, B: 1wt%, P: 2wt%, Co: 1wt%, C: 2wt%, Cr: 3.5wt%, Mn: 1wt%.

[0017] Furthermore, the specific steps of double-layer coating the prepared iron-based alloy magnetic powder are as follows:

[0018] The iron-based alloy magnetic powder is subjected to phosphoric acid passivation insulation coating treatment to obtain a first coated powder;

[0019] Pressing the first coated powder into a ring-shaped sample and performing a pressure resistance test;

[0020] performing a second coating process on the first coated powder to obtain a second coated powder;

[0021] The second coated powder is extruded and granulated using a mesh screen to obtain iron-based alloy coated powder particles.

[0022] Furthermore, the specific steps of the phosphoric acid passivation insulation coating treatment are: using phosphoric acid, a coupling agent and nano-scale fumed silica to form a layer of inorganic insulation coating film on the surface of the alloy magnetic powder.

[0023] Furthermore, the second coated powder is composed of iron-based alloy magnetic powder and thermosetting coating liquid; the thermosetting coating liquid includes phenolic resin, amine hardener, K540 coupling agent, and natural wax in a mass percentage range of 1wt%, 0.5wt%, 0.3wt%, and 0.5wt%, respectively.

[0024] Furthermore, the magnetic core is an I-shaped magnetic core, and a flat copper wire is used to wind the center column of the I-shaped magnetic core, and the flat copper wire is bent and extended from the bottom to serve as a bottom electrode.

[0025] Furthermore, the specific steps of placing the iron-based alloy coated powder into the wound magnetic core for low-pressure plastic sealing are as follows:

[0026] A high-frequency preheater is used to preheat the iron-based alloy coated powder particles to obtain plastic-sealed composite magnetic powder materials;

[0027] Adding the obtained plastic-sealed composite magnetic powder material into a mold;

[0028] The die ejector rod is pushed downward to cause the heat-softened plastic-encapsulated composite magnetic powder material to flow forward into the core mold cavity where the winding is placed;

[0029] When the plastic-encapsulated composite magnetic powder material fills the entire mold cavity, the curing process begins to complete the low-pressure plastic-encapsulation molding of the one-piece molded inductor.

[0030] A second aspect of the present invention provides an inductor manufactured by the method for manufacturing an inductor based on low-voltage plastic packaging molding according to the first aspect.

[0031] One or more of the above technical solutions have the following beneficial effects:

[0032] The present invention discloses an inductor based on low-voltage plastic sealing and a preparation method thereof. Compared with a conventional high-voltage (about 650MPa) integrally formed inductor, the present invention prepares the integrally formed inductor by adopting a low-voltage (20-80MPa) plastic sealing process on the basis of preparing a plastic-sealed composite magnetic powder material. The corresponding inductor product has the characteristics of high density and low internal stress, thereby enabling it to have the advantages of relatively high effective magnetic permeability, high strength and low high-frequency loss.

[0033] Compared with the conventional high-voltage preparation process of the integrally molded inductor, the low-voltage plastic packaging molding process adopted by the present invention can effectively reduce the deformation of the coil during the magnetic powder molding process, thereby facilitating the improvement of the reliability of the corresponding inductor product;

[0034] Compared with other existing process technologies, the method for preparing a high-density one-piece molded inductor based on a plastic packaging molding process provided by the present invention has the advantages of fewer production processes, simple manufacturing, and easy automation.

[0035] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0037] Figure 1 It is a flow chart of an inductor based on low-voltage plastic packaging molding and a preparation method thereof in the present invention;

[0038] Figure 2 It is a schematic diagram of the inductor structure based on low-voltage plastic packaging molding in the present invention;

[0039] Figure 3 This is a comparison diagram of the metallographic cross-section of the integrally formed inductor of Comparative Example 1 and Example 3 of the present invention. DETAILED DESCRIPTION

[0040] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0041] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "include" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or their combinations;

[0042] The present invention provides a method for preparing an inductor based on low-voltage plastic packaging molding, such as Figure 1 As shown, the following steps are included:

[0043] Step 1: The iron-based alloy magnetic powder is prepared by gas atomization. The powder prepared by the gas atomization method has higher sphericity and lower oxygen content.

[0044] The specific steps of preparing iron-based alloy magnetic powder by gas atomization are as follows:

[0045] Step 1.1: First, the master alloy raw materials are melted under high temperature conditions to form molten steel.

[0046] In a specific embodiment, the high temperature condition has a temperature of 1400°C to 1700°C.

[0047] Step 1.2: The molten steel is then sprayed out through the spray plate holes under the action of gravity and pressure, and is dispersed by high-pressure nitrogen to form iron-based alloy magnetic powder in the cooling tower.

[0048] In a specific embodiment, the particle size of the iron-based alloy magnetic powder ranges from 6 μm to 110 μm.

[0049] The composition of the iron-based alloy magnetic powder is: Fe: 79.6wt%, Nb: 4.0wt%, Si: 5.9wt%, B: 1wt%, P: 2wt%, Co: 1wt%, C: 2wt%, Cr: 3.5wt%, Mn: 1wt%.

[0050] Step 2: Double-coating the prepared iron-based alloy magnetic powder to obtain iron-based alloy coated powder particles.

[0051] The specific steps of double-layer coating the prepared iron-based alloy magnetic powder are as follows:

[0052] Step 2.1: The iron-based alloy magnetic powder is subjected to phosphoric acid passivation insulation coating treatment to obtain a first coated powder.

[0053] In a specific embodiment, the specific steps of the phosphoric acid passivation insulation coating treatment are: using phosphoric acid, a coupling agent and nano-scale fumed silica to form a layer of inorganic insulation coating film on the surface of the alloy magnetic powder.

[0054] Step 2.2: Press the first coated powder into a ring-shaped sample and perform a pressure test.

[0055] In a specific implementation, the pressure in the withstand voltage test is above 400V.

[0056] Step 2.3: Perform a second coating treatment on the first coated powder to obtain a second coated powder.

[0057] Step 2.4: The second coated powder is extruded and granulated using a mesh screen to obtain iron-based alloy coated powder particles.

[0058] In a specific embodiment, the second coated powder is composed of iron-based alloy magnetic powder and thermosetting coating liquid; the thermosetting coating liquid includes phenolic resin, amine hardener, K540 coupling agent, and natural wax in a mass percentage range of 1wt%, 0.5wt%, 0.3wt%, and 0.5wt%, respectively.

[0059] In a specific embodiment, the phenolic resin is at least one of phenol formaldehyde type phenolic resin, polymer of bisphenol F epichlorohydrin, 2,2'-[1,6-phenylene (1-oxymethylene)] dioxirane, and biphenyl phenol type phenolic resin.

[0060] In a specific embodiment, the second coating powder is composed of 95 wt % of iron-based alloy magnetic powder and 5 wt % of thermosetting coating liquid.

[0061] In a specific embodiment, the second coated powder is extruded and granulated using a stainless steel mesh screen, and the fluidity of the obtained iron-based alloy coated powder particles is 35s±5s; the mesh number of the granulation screen is 40 meshes.

[0062] Step 3: Sintering to prepare the magnetic core and winding the magnetic core.

[0063] In a specific embodiment, the magnetic core is an I-shaped magnetic core, which is sintered under nitrogen or argon atmosphere protection. Flat copper wire is used to wind the middle column of the I-shaped magnetic core, and the flat copper wire is bent and extended from the bottom as the bottom electrode. Compared with the welding strip, the design space of the wire package is larger.

[0064] In a specific embodiment, the sintering temperature ranges from 650° C. to 740° C., and the sintering time is 3 hours.

[0065] In a specific embodiment, the soft magnetic alloy material for the I-shaped magnetic core is one or more of iron-silicon-chromium, iron-silicon, iron-silicon-aluminum, and iron-nickel alloy powder.

[0066] Step 4: Place the iron-based alloy coated powder particles into the wound magnetic core for low-voltage plastic sealing to obtain the prepared inductor.

[0067] The specific steps of placing the iron-based alloy coated powder into the wound magnetic core for low-pressure plastic sealing are as follows:

[0068] Step 4.1: Use a high-frequency preheater to preheat the iron-based alloy coated powder particles to obtain plastic-encapsulated composite magnetic powder materials.

[0069] In a specific embodiment, the second layer of coated powder is thermosetting and can increase the bonding strength between the powders, and the first layer of coated powder is an insulating layer and can increase the resistance. In view of the fact that the coating layer formed by the second coated powder on the surface of the obtained iron-based alloy coated powder particles has thermosetting properties, the obtained iron-based alloy coated powder particles need to be preheated with a high-frequency preheating machine to obtain a plastic-sealed composite magnetic powder material, wherein the preheating time is 20s to 60s and the preheating temperature is 75°C to 90°C.

[0070] Step 4.2: Add the obtained plastic-encapsulated composite magnetic powder material into the mold.

[0071] Step 4.3: Push the die ejector downward to force the heat-softened plastic-encapsulated composite magnetic powder material to flow forward into the core mold cavity where the winding is placed.

[0072] Step 4.4: When the plastic-encapsulated composite magnetic powder fills the entire mold cavity, the curing process begins to complete the low-pressure plastic encapsulation molding of the one-piece molded inductor.

[0073] In a specific implementation, negative pressure mold flow technology is used to eliminate internal voids and delamination defects and other appearance defects of the one-piece molded inductor product, which can make the filling effect more excellent and help achieve better density. In addition, low-pressure heating and curing work at the same time, which is conducive to further increasing the density of the magnet.

[0074] Specifically, the compression molding pressure ranges from 20MPa to 70MPa, the entire ejector pushing time ranges from 5s to 30s, the curing temperature ranges from 170°C to 180°C during the curing process, and the curing time ranges from 30s to 180s.

[0075] Step 5: Strip the paint and electroplate the two ends of the flat copper wire to complete the preparation of the one-piece inductor device. The prepared inductor is as follows: Figure 2 shown.

[0076] With the continuous innovation of the process technology of one-piece molded inductors, automotive-grade inductors have increasingly higher requirements for their reliability and aging resistance. Traditional molded inductors are obtained by high-pressure molding of embedded coils. The coils are easily deformed, resulting in increased DCR. In addition, the irregular metal alloy powder is hard in texture, which easily leads to poor turn-to-turn withstand voltage after being embedded in the coil. The present invention is based on the transfer plastic packaging technology and provides a method for preparing a high-performance, low-loss one-piece molded inductor based on low-voltage plastic packaging molding. The inductor structure is as follows: Figure 2 As shown, it includes a sintered I-shaped sintered magnetic core, a flat coil, a composite plastic sealing layer, a positioning hole and a bottom electroplated terminal. It is characterized in that the soft magnetic powder used in the composite layer is coated with a double layer of inorganic and organic layers, which on the one hand increases the surface resistance of the powder and reduces the eddy current loss, and on the other hand, the low-pressure molding will not cause damage to the harder inorganic insulation layer. The sintered magnetic core can make the inductor have a higher effective magnetic permeability. The production process has the advantages of fewer production processes, simple manufacturing, and easy automation, which is conducive to industrial promotion.

[0077] In order to better illustrate the inductor preparation method of the present invention, the following comparative examples and embodiment experiments are used for comparison and explanation:

[0078] Comparative Example 1

[0079] This example is for the composition of Fe 73.72 Si 11 B 11 C2Cr 2.28 The water-gas combined atomization of Fe-based amorphous alloy powder (FeSiBCCr) is used to prepare an integrated inductor product by high pressure molding. The specific implementation method is as follows:

[0080] Step 1: Passivation insulation coating treatment is performed on the iron-based amorphous alloy magnetic powder using phosphoric acid (0.5wt.%), a coupling agent (0.5wt.%) and nano-grade fumed silica (1.0wt.%) to obtain a first coated powder; the first coated powder (96wt%) is fully mixed with a thermosetting coating liquid (4.0wt%) to obtain a second coated powder, wherein the thermosetting coating liquid (4.0wt%) is composed of bisphenol F epichlorohydrin The invention relates to a method for preparing the invention which comprises the following steps: the first step of preparing the second coated powder and the second step of preparing the second coated powder. The first step of preparing the second coated powder comprises: a polymer (2.6wt%), 2,2'-[1,6-phenylene(1-oxymethylene)]dioxirane (0.4wt%), an amine hardener (0.5wt%), a K540 coupling agent (0.25wt%), and a natural wax (0.25wt%); finally, the second coated powder is extruded and granulated using a stainless steel mesh screen, and the fluidity of the obtained iron-based alloy coated powder particles is 32s; the mesh number of the granulation mesh screen is 40 meshes.

[0081] Step 2: First, the I-shaped magnetic core made of the alloy material of Sendust is sintered under nitrogen atmosphere protection conditions, wherein the sintering temperature range is 720°C and the sintering time is 3 hours; secondly, the flat copper wire is wound around the center column of the obtained I-shaped magnetic core, and the flat copper wire is bent and extended from the bottom as the bottom electrode.

[0082] Step 3: First, add the iron-based amorphous alloy coated powder obtained in step 1 into the mold cavity containing the wound I-shaped magnetic core obtained in step 2, and press at a pressure of 650 MPa to obtain an one-piece molded inductor. Then, strip the paint and electroplate the two ends of the flat copper wire in step 2 to complete the preparation of the one-piece molded inductor device.

[0083] Example 1

[0084] This example is for the composition of Fe bal. Si 4.0 Cr 4.5 The atomized FeSiCr magnetic powder is used to prepare an integrated inductor product using a low-pressure plastic sealing process. The specific implementation method is as follows:

[0085] Step 1: Passivation insulation coating treatment is performed on the iron-based amorphous alloy magnetic powder using phosphoric acid (0.5wt.%), a coupling agent (0.5wt.%) and nano-grade fumed silica (1.0wt.%) to obtain a first coated powder; the first coated powder (96wt%) is fully mixed with a thermosetting coating liquid (4.0wt%) to obtain a second coated powder, wherein the thermosetting coating liquid (4.0wt%) is composed of bisphenol F epichlorohydrin The invention relates to a method for preparing the invention which comprises the following steps: the first step of preparing the second coated powder and the second step of preparing the second coated powder. The first step of preparing the second coated powder comprises: a polymer (2.6wt%), 2,2'-[1,6-phenylene(1-oxymethylene)]dioxirane (0.4wt%), an amine hardener (0.5wt%), a K540 coupling agent (0.25wt%), and a natural wax (0.25wt%); finally, the second coated powder is extruded and granulated using a stainless steel mesh screen, and the fluidity of the obtained iron-based alloy coated powder particles is 30s; the mesh number of the granulation mesh screen is 40 meshes.

[0086] Step 2: First, the I-shaped magnetic core made of the alloy material of Sendust is sintered under nitrogen atmosphere protection conditions, wherein the sintering temperature range is 720°C and the sintering time is 3 hours; secondly, the flat copper wire is wound around the center column of the obtained I-shaped magnetic core, and the flat copper wire is bent and extended from the bottom as the bottom electrode.

[0087] Step 3: First, a high-frequency preheating machine is used to preheat the iron-based amorphous alloy coated powder particles obtained in step 1 to obtain a plastic-encapsulated composite magnetic powder material, wherein the preheating time is 40 seconds and the preheating temperature is 85°C; secondly, the obtained plastic-encapsulated composite magnetic powder material is added to the mold; then, a die ejector is used to push downward to promote the heat-softened plastic-encapsulated composite magnetic powder material to flow forward and enter the mold cavity containing the wound I-shaped magnetic core obtained in step 2; finally, when the plastic-encapsulated composite magnetic powder material fills the entire mold cavity, the curing process is started to complete the low-pressure plastic-encapsulation molding of the one-piece molded inductor; wherein in order to eliminate the internal voids and delamination defects and other appearance defects of the one-piece molded inductor product, the die pressure range is 40MPa, the entire ejector pushing time range is 15s, the mold temperature range in the curing process is 175°C, and the curing time range is 140s.

[0088] Step 4: After stripping and electroplating the two ends of the flat copper wire reserved in step 2, the preparation of the one-piece molded inductor device is completed.

[0089] Example 2

[0090] This example is for the composition of Fe 85wt％ Si 9wt％ Al 6wt％ The atomized FeSiAl magnetic powder is used to prepare an integrated inductor product using a low-pressure plastic sealing process. The specific implementation method is as follows:

[0091] Step 1: Passivation insulation coating treatment is performed on the iron-based amorphous alloy magnetic powder using phosphoric acid (0.5wt.%), a coupling agent (0.5wt.%) and nano-grade fumed silica (1.0wt.%) to obtain a first coated powder; the first coated powder (96wt%) is fully mixed with a thermosetting coating liquid (4.0wt%) to obtain a second coated powder, wherein the thermosetting coating liquid (4.0wt%) is composed of bisphenol F epichlorohydrin The invention relates to a method for preparing the invention which comprises the following steps: the first step of preparing the second coated powder and the second step of preparing the second coated powder. The first step of preparing the second coated powder comprises: a polymer (2.6wt%), 2,2'-[1,6-phenylene(1-oxymethylene)]dioxirane (0.4wt%), an amine hardener (0.5wt%), a K540 coupling agent (0.25wt%), and a natural wax (0.25wt%); finally, the second coated powder is extruded and granulated using a stainless steel mesh screen, and the fluidity of the obtained iron-based alloy coated powder particles is 30s; the mesh number of the granulation mesh screen is 40 meshes.

[0092] Step 2: First, the I-shaped magnetic core made of the alloy of sendust is sintered under nitrogen atmosphere protection, wherein the sintering temperature range is 720°C and the sintering time is 3h; secondly, Figure 1 As shown, a flat copper wire is used to wind the obtained I-shaped magnetic core center column, and the flat copper wire is bent and extended from the bottom to serve as a bottom electrode.

[0093] Step 3: First, a high-frequency preheating machine is used to preheat the iron-based amorphous alloy coated powder particles obtained in step 1 to obtain a plastic-encapsulated composite magnetic powder material, wherein the preheating time is 40 seconds and the preheating temperature is 85°C; secondly, the obtained plastic-encapsulated composite magnetic powder material is added to the mold; then, a die ejector is used to push downward to promote the heat-softened plastic-encapsulated composite magnetic powder material to flow forward and enter the mold cavity containing the wound I-shaped magnetic core obtained in step 2; finally, when the plastic-encapsulated composite magnetic powder material fills the entire mold cavity, the curing process is started to complete the low-pressure plastic-encapsulation molding of the one-piece molded inductor; wherein in order to eliminate the internal voids and delamination defects and other appearance defects of the one-piece molded inductor product, the die pressure range is 40MPa, the entire ejector pushing time range is 18s, the mold temperature range in the curing process is 173°C, and the curing time range is 140s.

[0094] Step 4: After stripping and electroplating the two ends of the flat copper wire in step 2, the preparation of the one-piece molded inductor device is completed.

[0095] Example 3

[0096] This embodiment uses a low-pressure plastic sealing process to prepare an integrated inductor product using atomized FeBPNbCr amorphous magnetic powder. The specific implementation method is as follows:

[0097] Step 1: Passivation insulation coating treatment is performed on the iron-based amorphous alloy magnetic powder using phosphoric acid (0.5wt.%), a coupling agent (0.5wt.%) and nano-grade fumed silica (1.0wt.%) to obtain a first coated powder; the first coated powder (96wt%) is fully mixed with a thermosetting coating liquid (4.0wt%) to obtain a second coated powder, wherein the thermosetting coating liquid (4.0wt%) is composed of bisphenol F epichlorohydrin The invention relates to a method for preparing the invention which comprises the following steps: the first step of preparing the second coated powder and the second step of preparing the second coated powder. The first step of preparing the second coated powder comprises: a polymer (2.6wt%), 2,2'-[1,6-phenylene(1-oxymethylene)]dioxirane (0.4wt%), an amine hardener (0.5wt%), a K540 coupling agent (0.25wt%), and a natural wax (0.25wt%); finally, the second coated powder is extruded and granulated using a stainless steel mesh screen, and the fluidity of the obtained iron-based alloy coated powder particles is 30s; the mesh number of the granulation mesh screen is 40 meshes.

[0098] Step 2: First, the I-shaped magnetic core made of the alloy of sendust is sintered under nitrogen atmosphere protection, wherein the sintering temperature range is 720°C and the sintering time is 3h; secondly, Figure 1 As shown, a flat copper wire is used to wind the obtained I-shaped magnetic core center column, and the flat copper wire is bent and extended from the bottom to serve as a bottom electrode.

[0099] Step 3: First, a high-frequency preheating machine is used to preheat the iron-based amorphous alloy coated powder particles obtained in step 1 to obtain a plastic-encapsulated composite magnetic powder material, wherein the preheating time is 40 seconds and the preheating temperature is 85°C; secondly, the obtained plastic-encapsulated composite magnetic powder material is added to the mold; then, a die ejector is used to push downward to promote the heat-softened plastic-encapsulated composite magnetic powder material to flow forward and enter the mold cavity containing the wound I-shaped magnetic core obtained in step 2; finally, when the plastic-encapsulated composite magnetic powder material fills the entire mold cavity, the curing process is started to complete the low-pressure plastic-encapsulation molding of the one-piece molded inductor; wherein in order to eliminate the internal voids and delamination defects and other appearance defects of the one-piece molded inductor product, the die pressure range is 40MPa, the entire ejector pushing time range is 18s, the mold temperature range in the curing process is 173°C, and the curing time range is 140s.

[0100] Step 4: After stripping and electroplating the two ends of the flat copper wire in step 2, the preparation of the one-piece molded inductor device is completed.

[0101] Example 4

[0102] This embodiment uses a low-pressure plastic sealing process to prepare an integrated inductor product using atomized FeSiCr magnetic powder. The specific implementation method is as follows:

[0103] Step 1: Passivation insulation coating treatment is performed on the iron-based amorphous alloy magnetic powder by using phosphoric acid (0.5wt.%), a coupling agent (0.5wt.%) and nano-grade fumed silica (1.0wt.%) to obtain a first coated powder; the first coated powder (96.0wt%) is fully mixed with a thermosetting coating liquid (5.0wt%) to obtain a second coated powder, wherein the thermosetting coating liquid (5.0wt%) is composed of bisphenol F epoxy chloride. The invention relates to a method for preparing a second coated powder, comprising: preparing the first coating powder and the second coated powder; the first coating powder is prepared by extruding and granulating the second coated powder using a stainless steel mesh screen, and the fluidity of the obtained iron-based alloy coated powder particles is 30s; and the mesh number of the granulation mesh screen is 40 meshes.

[0104] Step 2: First, the I-shaped magnetic core made of the alloy of sendust is sintered under nitrogen atmosphere protection, wherein the sintering temperature range is 720°C and the sintering time is 3h; secondly, Figure 1 As shown, a flat copper wire is used to wind the obtained I-shaped magnetic core center column, and the flat copper wire is bent and extended from the bottom to serve as a bottom electrode.

[0105] Step 3: First, a high-frequency preheating machine is used to preheat the iron-based amorphous alloy coated powder particles obtained in step 1 to obtain a plastic-encapsulated composite magnetic powder material, wherein the preheating time is 40 seconds and the preheating temperature is 85°C; secondly, the obtained plastic-encapsulated composite magnetic powder material is added to the mold; then, a die ejector is used to push downward to promote the heat-softened plastic-encapsulated composite magnetic powder material to flow forward and enter the mold cavity containing the wound I-shaped magnetic core obtained in step 2; finally, when the plastic-encapsulated composite magnetic powder material fills the entire mold cavity, the curing process is started to complete the low-pressure plastic-encapsulation molding of the one-piece molded inductor; wherein in order to eliminate the internal voids and delamination defects and other appearance defects of the one-piece molded inductor product, the die pressure range is 40MPa, the entire ejector pushing time range is 20 seconds, the mold temperature range in the curing process is 176°C, and the curing time range is 140 seconds.

[0106] Step 4: After stripping and electroplating the two ends of the flat copper wire in step 2, the preparation of the one-piece molded inductor device is completed.

[0107] Example 5

[0108] This embodiment uses a low-pressure plastic sealing process to prepare an integrated inductor product using atomized FeSiCr magnetic powder. The specific implementation method is as follows:

[0109] Step 1: Passivation insulation coating treatment is performed on the iron-based amorphous alloy magnetic powder using phosphoric acid (0.5wt.%), a coupling agent (0.5wt.%) and nano-grade fumed silica (1.0wt.%) to obtain a first coated powder; the first coated powder (96wt%) is fully mixed with a thermosetting coating liquid (4.0wt%) to obtain a second coated powder, wherein the thermosetting coating liquid (4.0wt%) is composed of bisphenol F epichlorohydrin The invention relates to a method for preparing the invention which comprises the following steps: the first step of preparing the second coated powder and the second step of preparing the second coated powder. The first step of preparing the second coated powder comprises: a polymer (2.6wt%), 2,2'-[1,6-phenylene(1-oxymethylene)]dioxirane (0.4wt%), an amine hardener (0.5wt%), a K540 coupling agent (0.25wt%), and a natural wax (0.25wt%); finally, the second coated powder is extruded and granulated using a stainless steel mesh screen, and the fluidity of the obtained iron-based alloy coated powder particles is 30s; the mesh number of the granulation mesh screen is 40 meshes.

[0110] Step 2: First, the I-shaped magnetic core made of the alloy of sendust is sintered under nitrogen atmosphere protection, wherein the sintering temperature range is 720°C and the sintering time is 3h; secondly, Figure 1 As shown, a flat copper wire is used to wind the obtained I-shaped magnetic core center column, and the flat copper wire is bent and extended from the bottom to serve as a bottom electrode.

[0111] Step 3: First, a high-frequency preheating machine is used to preheat the iron-based amorphous alloy coated powder particles obtained in step 1 to obtain a plastic-encapsulated composite magnetic powder material, wherein the preheating time is 40 seconds and the preheating temperature is 85°C; secondly, the obtained plastic-encapsulated composite magnetic powder material is added to the mold; then, a die ejector is used to push downward to promote the heat-softened plastic-encapsulated composite magnetic powder material to flow forward and enter the mold cavity containing the wound I-shaped magnetic core obtained in step 2; finally, when the plastic-encapsulated composite magnetic powder material fills the entire mold cavity, the curing process is started to complete the low-pressure plastic-encapsulation molding of the one-piece molded inductor; wherein in order to eliminate the internal voids and delamination defects and other appearance defects of the one-piece molded inductor product, the die pressure range is 35MPa, the entire ejector pushing time range is 20s, the mold temperature range in the curing process is 175°C, and the curing time range is 140s.

[0112] Step 4: After stripping and electroplating the two ends of the flat copper wire in step 2, the preparation of the one-piece molded inductor device is completed.

[0113] The experimental results of the above comparative example 1 and examples 1 to 5 are compared as shown in Table 1 and Table 2:

[0114] Table 1. Comparison of preparation steps between Comparative Example 1 and Examples 1 to 5

[0115] Project Team Magnetic powder material Thermosetting coating liquid content, wt% Molding pressure, MPa Comparative Example 1 FeSiBCCr amorphous powder 4.0 650 Example 1 FeSiCr alloy powder 4.0 40 Example 2 FeSiAl alloy powder 4.0 40 Example 3 FeBPNbCr amorphous powder 4.0 40 Example 4 FeSiCr alloy powder 5.0 40 Example 5 FeSiCr alloy powder 4.0 35

[0116] Table 2. Comparison of inductance performances of Comparative Example 1 and Examples 1 to 5

[0117]

[0118] Table 1 shows the content of thermosetting coating liquid in the one-piece molded inductor in Comparative Example 1 and Examples 1 to 5 and its molding pressure. Table 2 shows the electromagnetic properties and mechanical properties of the corresponding inductor products. Comparing Comparative Example 1 and Examples 1 to 3, it can be seen that compared with the conventional high-pressure (about 650MPa) one-piece molded inductor, since the present scheme adopts a low-pressure (20-80MPa) plastic sealing molding process to prepare the one-piece molded inductor on the basis of preparing plastic-sealed composite magnetic powder materials, the corresponding inductor product has the characteristics of high density and low internal stress, which in turn enables it to have relatively high effective magnetic permeability, high strength and low high-frequency loss. The advantages include, among which the inductor molding density can be increased from 5.67g / cm3 to 6.25g / cm3 at a maximum, and the effective magnetic permeability It can be increased from 18.5 to a maximum of 44.7, and the bending strength can be increased from 78MPa to a maximum of 97MPa, while the corresponding loss value 90@1MHz, 10mT can be reduced from 266kW / m3 to 90kW / m3, which is beneficial to the improvement of the comprehensive electromagnetic properties of the one-piece molded inductor product; at the same time, by comparing Examples 1, 4 and 5, it can be seen that increasing the content of the thermosetting coating liquid will lead to an increase in the magnetic permeability of the inductor product, but will increase its bending strength; reducing the molding pressure will lead to a decrease in the magnetic permeability and bending strength of the inductor product, but will be beneficial to reducing the loss.

[0119] In addition, since the one-piece molded inductor of the present invention is prepared by a low-pressure (20-80 MPa) plastic packaging molding process, Figure 3 As shown, compared with the conventional high-voltage (about 650MPa) one-piece molded inductor, the one-piece molded inductor prepared by the present invention has no internal flat copper wire deformation extrusion, which is beneficial to increase the reliability of the one-piece molded inductor product.

[0120] Embodiment 2:

[0121] Embodiment 2 of the present invention provides an inductor manufactured by the method for manufacturing an inductor based on low-voltage plastic packaging molding described in Embodiment 1.

[0122] The steps involved in the above embodiment 2 correspond to those in the method embodiment 1. For the specific implementation method, please refer to the relevant description part of the embodiment 1.

[0123] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A method for preparing an inductor based on low-voltage plastic packaging, characterized in that: The following steps are involved: The iron-based alloy magnetic powder is prepared by gas atomization method; Double-coating the prepared iron-based alloy magnetic powder to obtain iron-based alloy coated powder particles; Sintering to prepare a magnetic core, and winding the magnetic core; The iron-based alloy coated powder particles are placed in the wound magnetic core for low-voltage plastic sealing to obtain the prepared inductor.

2. The method for preparing an inductor based on low-voltage plastic packaging molding according to claim 1, characterized in that: The specific steps of preparing iron-based alloy magnetic powder by gas atomization are: The master alloy raw materials are first melted under high temperature conditions to form molten steel, and then the molten steel is sprayed out through the leakage holes of the spray plate under the action of gravity and pressure, and is dispersed by high-pressure nitrogen to form iron-based alloy magnetic powder in the cooling tower.

3. The method for preparing an inductor based on low-voltage plastic packaging molding according to claim 2, characterized in that: The particle size range of the iron-based alloy magnetic powder is 6 μm to 110 μm.

4. The method for preparing an inductor based on low-voltage plastic packaging molding according to claim 3, characterized in that: The composition of the iron-based alloy magnetic powder is: Fe: 75% to 92%, Nb: 3.0% to 6.0%, Si: 3.0% to 6.0%, B: 0.5% to 2%, P: 1% to 4%, Co: 0.1% to 0.5%, C: 0.5% to 1%, Cr: 0.5% to 3%, and Mn: 0.1% to 1%.

5. The method for preparing an inductor based on low-voltage plastic packaging molding according to claim 1, characterized in that: The specific steps of double-layer coating the prepared iron-based alloy magnetic powder are as follows: The iron-based alloy magnetic powder is subjected to phosphoric acid passivation insulation coating treatment to obtain a first coated powder; Pressing the first coated powder into a ring-shaped sample and performing a pressure resistance test; performing a second coating process on the first coated powder to obtain a second coated powder; The second coated powder is extruded and granulated using a mesh screen to obtain iron-based alloy coated powder particles.

6. The method for preparing an inductor based on low-voltage plastic packaging molding according to claim 5, characterized in that: The specific steps of the phosphoric acid passivation insulation coating treatment are: using phosphoric acid, a coupling agent and nano-scale gas-phase silicon dioxide to form a layer of inorganic insulation coating film on the surface of the alloy magnetic powder.

7. The method for preparing an inductor based on low-voltage plastic packaging molding according to claim 6, characterized in that: The second coated powder is composed of iron-based alloy magnetic powder and thermosetting coating liquid; the thermosetting coating liquid includes phenolic resin, amine hardener, K540 coupling agent, and natural wax, and the mass percentage content ranges are 1% to 2%, 0.1% to 1%, 0.1% to 1%, and 0.1% to 1%, respectively.

8. The method for preparing an inductor based on low-voltage plastic packaging molding according to claim 1, characterized in that: The magnetic core is an I-shaped magnetic core, and a flat copper wire is used to wind the center column of the I-shaped magnetic core. The flat copper wire is bent and extended from the bottom to serve as a bottom electrode.

9. The method for preparing an inductor based on low-voltage plastic packaging molding according to claim 1, characterized in that: The specific steps of placing the iron-based alloy coated powder into the wound magnetic core for low-pressure plastic sealing are as follows: A high-frequency preheater is used to preheat the iron-based alloy coated powder particles to obtain plastic-sealed composite magnetic powder materials; Adding the obtained plastic-sealed composite magnetic powder material into a mold; The die ejector rod is pushed downward to cause the heat-softened plastic-encapsulated composite magnetic powder material to flow forward into the core mold cavity where the winding is placed; When the plastic-encapsulated composite magnetic powder material fills the entire mold cavity, the curing process begins to complete the low-pressure plastic-encapsulation molding of the one-piece molded inductor.

10. An inductor manufactured by the method for manufacturing an inductor based on low-voltage plastic packaging molding according to any one of claims 1 to 9.

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