Iron-based alloy powder, preparation method of transfer plastic package integrally-formed inductor and inductor

Abstract

The invention belongs to the field of integrally-formed inductor preparation, and provides iron-based alloy powder, a preparation method of a transfer plastic package integrally-formed inductor and the inductor. In order to solve the problem of a formula of atomized powder with high magnetic conductivity and high bias, the iron-based alloy powder is provided and comprises the following components in percentage by weight: 75 to 92 percent of Fe, 5 to 10 percent of Ni, 3.0 to 5.0 percent of Si, 0.5 to 2 percent of B, 1 to 2 percent of P, 0.1 to 0.5 percent of Co, 0.5 to 1 percent of C, 0.5 to 3 percent of Cr and 0.1 to 1 percent of Mn. And the magnetic conductivity and the saturation characteristic of the alloy iron-silicon-chromium powder can be improved.

Description

Technical Field

[0001] The present invention belongs to the field of integrated molded inductor preparation, and in particular relates to an iron-based alloy powder, a preparation method of a transfer plastic-sealed integrated molded inductor, and an inductor. 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] At present, the preparation processes of inductors include winding type, laminated type, integrated molding and thin film inductors. Among them, the winding type inductor generally prefabricates the magnetic core before winding, and needs to be shielded with magnetic glue. Due to its structural defects, there is a large leakage flux, which will interfere with nearby magnetic components. The laminated inductor is formed by slurry casting and lamination. The solid content of the magnetic phase is 50%-60%. The density of the magnet after sintering is low, and the performance of the prepared inductor is slightly low. The integrated inductor needs to be formed by high pressure, which will cause the coil to deform and cause problems such as the voltage resistance difference between turns. It requires a thickened paint film and special copper wire. There is a great risk of product reliability, and the high pressure makes it difficult to eliminate the internal stress formed by the magnetic powder, resulting in excessive inductance loss and low temperature rise current. Summary of the invention

[0004] In order to solve the technical problems existing in the above-mentioned background technology, the present invention provides an iron-based alloy powder, a preparation method of a transfer plastic-sealed integrated inductor and an inductor, wherein the iron-based alloy powder can improve the magnetic permeability and saturation characteristics of the alloy iron-silicon-chromium powder; and the integrated inductor prepared by the preparation method of the transfer plastic-sealed integrated inductor has excellent electrical characteristics, not only excellent performance, but also very high reliability, and can improve the short-circuit reliability of the molded inductor.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A first aspect of the present invention provides an iron-based alloy powder.

[0007] An iron-based alloy powder comprises the following components by weight percentage: Fe: 75-92%, Ni: 5-10%, Si: 3.0-5.0%, B: 0.5-2%, P: 1-2%, Co: 0.1-0.5%, C: 0.5-1%, Cr: 0.5-3%, and Mn: 0.1-1%.

[0008] As an implementation mode, in the process of preparing the iron-based alloy powder, the component materials of the iron-based alloy powder are atomized to obtain iron-based alloy particles; and then the iron-based alloy particles are dispersed by setting high temperature and high frequency smelting and high pressure to form an iron-based alloy powder.

[0009] A second aspect of the present invention provides a method for preparing a transfer plastic-encapsulated integrated inductor.

[0010] A method for preparing a transfer plastic-sealed integrated inductor, comprising:

[0011] The iron-based alloy powder as described above is subjected to secondary coating and extrusion granulation treatment to obtain plastic-encapsulated composite magnetic powder particles;

[0012] preparing a sintered magnetic core and winding a coil thereon;

[0013] Placing the plastic-encapsulated composite magnetic powder particles and the sintered magnetic core with the wound coil into a transfer injection molding mold for compression molding;

[0014] The inductor after compression molding is subjected to terminal stripping, tinning and folding treatment to prepare a transfer plastic-sealed integrated inductor.

[0015] As an embodiment, the process of performing secondary coating treatment on the iron-based alloy powder includes:

[0016] Phosphoric acid, a coupling agent and nano-scale fumed silica are used to form an inorganic insulating layer on the surface of the iron-based alloy powder to obtain a first coated powder;

[0017] The first coating powder is coated for the second time with a thermosetting epoxy resin layer; wherein the mass percentages of the thermosetting epoxy resin layer and the first coating powder are 3% to 10% and 90% to 97% respectively.

[0018] As an embodiment, the phenolic resin in the thermosetting epoxy resin layer is at least one of phenol formaldehyde type phenolic resin, polymer of bisphenol F epichlorohydrin, 2,2'-[1,6-phenylene (1-oxymethylene)] dioxirane, and biphenylphenol type phenolic resin.

[0019] As an embodiment, the components of the thermosetting epoxy resin layer are a polymer of bisphenol F epichlorohydrin, 2,2'-[1,6-phenylene(1-oxymethylene)]dioxirane, an amine hardener, a K550 coupling agent and a natural wax, and the mass percentages thereof are 1% to 2%, 0.2% to 0.5%, 0.1% to 1%, 0.1% to 1% and 0.1% to 1%, respectively.

[0020] As an implementation mode, during the extrusion granulation process after the secondary coating of the iron-based alloy powder, the granulation screen used has a mesh size of 50 and a fluidity of 35±5s.

[0021] As an implementation mode, in the process of preparing the sintered magnetic core, the magnetic core is sintered at 600° C. to 750° C. for 3 hours under the condition of atmosphere protection and kept warm for 1.5 hours.

[0022] As an embodiment, after placing the plastic-encapsulated composite magnetic powder particles into a transfer injection molding mold, the method further includes: preheating the plastic-encapsulated composite magnetic powder particles, wherein the preheating temperature is the mold surface temperature.

[0023] As an implementation method, the process of placing the plastic-encapsulated composite magnetic powder particles and the sintered magnetic core with the wound coil into a transfer injection molding mold for compression molding includes:

[0024] The die punch is pushed downward to squeeze the plastic-encapsulated composite magnetic powder particles, so that the plastic-encapsulated composite magnetic powder particles are softened by heat and pressure, and are pushed forward along the transfer injection molding die channel;

[0025] The plastic-encapsulated composite magnetic powder particles are pushed into the mold cavity containing the wound sintered magnetic core and fill the entire mold cavity, and then begin to solidify, completing the compression molding process.

[0026] A third aspect of the present invention provides an inductor.

[0027] An inductor is prepared by using the steps in the preparation method of the transfer plastic encapsulation integrated inductor as described above.

[0028] The beneficial effects of the present invention are:

[0029] (1) The iron-based alloy powder of the present invention solves the problem of formulating atomized powder with high magnetic permeability and high bias, improves the magnetic permeability and saturation characteristics of the alloy iron-silicon-chromium powder, and increases the initial magnetic permeability of the soft iron-based alloy powder used for plastic packaging to 39% and the saturation magnetization intensity to 1.45T.

[0030] (2) The iron-based alloy powder of the present invention is prepared by gas atomization. Compared with the water atomization powder making method, the powder obtained by this method has better sphericity, which helps to improve the fluidity of the iron-based alloy powder.

[0031] (3) The present invention adopts transfer mold injection molding, which does not require complicated processes, has few and simple processes, is easy to automate, and can effectively reduce costs.

[0032] (4) The inductor obtained by the transfer plastic encapsulation integrated molded inductor preparation method of the present invention has lower loss and a magnetic density of up to 6.1 kg / m3. Compared with the integrated molded inductor, the use of a sintered magnetic core reduces the loss to 120 kw / m3 (1 MHz @ 10 mT).

[0033] 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

[0034] 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.

[0035] Figure 1 It is a schematic diagram of the preparation principle of the transfer plastic encapsulation integrated molded inductor according to an embodiment of the present invention;

[0036] Figure 2 It is a schematic diagram of the structure of a transfer plastic encapsulated integrated inductor manufactured in an embodiment of the present invention.

[0037] Among them: 1. Plastic-sealed composite magnetic powder particles; 2. Sintered magnetic core; 3. Coil; 4. Transfer injection molding mold; 5. Channel; 6. Die punch. DETAILED DESCRIPTION

[0038] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0039] It should be noted that the following detailed descriptions are all illustrative and 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.

[0040] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit 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 "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0041] 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. At present, the electronic information industry is developing rapidly. As one of the basic electronic components indispensable for industrial development, inductors are also constantly innovating, and are rapidly upgrading in terms of application, product performance, and quality. The development trend of the automotive inductor industry shows the characteristics of miniaturization, high frequency, high power, and modularization. Therefore, the performance and reliability of automotive inductors need to be better guaranteed.

[0042] In one or more embodiments, an iron-based alloy powder includes the following components by weight percentage: Fe: 75-92%, Ni: 5-10%, Si: 3.0-5.0%, B: 0.5-2%, P: 1-2%, Co: 0.1-0.5%, C: 0.5-1%, Cr: 0.5-3%, and Mn: 0.1-1%.

[0043] In the specific implementation process, in the process of preparing the iron-based alloy powder, the iron-based alloy particles are obtained by gas atomizing the component materials of the iron-based alloy powder; and then the iron-based alloy particles are dispersed by setting high temperature and high frequency smelting (such as: high frequency medium smelting at 1700°C) and high pressure to form an iron-based alloy powder. The particle size of the iron-based alloy particles is 6 to 110 μm.

[0044] The iron-based alloy powder of this embodiment solves the problem of high magnetic permeability and high bias atomized powder formulation, improves the magnetic permeability and saturation characteristics of the alloy iron-silicon-chromium powder, and increases the initial magnetic permeability of the soft iron-based alloy powder used for plastic packaging to 39% and the saturation magnetization intensity to 1.45T.

[0045] This embodiment also solves the problem of poor fluidity of coated magnetic powder for plastic packaging with a solid content of more than 95wt%. The alloy magnetic powder for plastic packaging prepared in this way has a spiral flowable distance of 60 to 98cm (180°C) and a solidification time of 80 to 180s at 180°C.

[0046] In one or more embodiments, a method for preparing a transfer plastic-encapsulated integrated inductor is provided, comprising:

[0047] Step 1: performing secondary coating and extrusion granulation treatment on the above-mentioned iron-based alloy powder to obtain plastic-encapsulated composite magnetic powder particles;

[0048] Step 2: Prepare a sintered magnetic core and wind a coil on it;

[0049] Step 3: placing the plastic-encapsulated composite magnetic powder particles and the sintered magnetic core with the wound coil into a transfer injection molding mold for compression molding;

[0050] Step 4: After the terminals of the die-cast inductor are stripped of paint and tinned, a transfer plastic-sealed integrated inductor is prepared. Figure 2 shown.

[0051] It should be noted here that the order of step 1 and step 2 can be swapped according to actual conditions.

[0052] The manufacturing process of this embodiment improves the high shielding characteristics, density and reliability of the chip inductor.

[0053] Specifically, in step 1, the process of performing secondary coating treatment on the iron-based alloy powder includes:

[0054] Step 1.1: using phosphoric acid, a coupling agent and nano-scale fumed silica to form an inorganic insulating layer on the surface of the iron-based alloy powder to obtain a first coated powder;

[0055] Step 1.2: The first coating powder is coated for a second time with a thermosetting epoxy resin layer; wherein the mass percentages of the thermosetting epoxy resin layer and the first coating powder are 3% to 10% and 90% to 97% respectively.

[0056] In step 1.1, the withstand voltage of the first coated powder after the pressing ring is obtained is above 500V; and the first coating (ie, passivation treatment) of the iron-based alloy powder improves the insulation performance of the alloy powder.

[0057] In step 1.2, the phenolic resin in the thermosetting epoxy resin layer is at least one of phenol formaldehyde type phenolic resin, polymer of bisphenol F epichlorohydrin, 2,2'-[1,6-phenylene (1-oxymethylene)] dioxirane, and biphenylphenol type phenolic resin.

[0058] In other embodiments, in step 1.2, the components of the thermosetting epoxy resin layer are a polymer of bisphenol F epichlorohydrin, 2,2'-[1,6-phenylene(1-oxymethylene)]dioxirane, an amine hardener, a K550 coupling agent and a natural wax, and the mass percentages thereof are 1% to 2%, 0.2% to 0.5%, 0.1% to 1%, 0.1% to 1% and 0.1% to 1%, respectively.

[0059] In step 1, during the extrusion granulation process after the secondary coating of the iron-based alloy powder, the granulation screen used has a mesh size of 50 and a fluidity of 35±5s.

[0060] In step 2, during the preparation of the sintered magnetic core, the magnetic core is sintered at 600° C. to 750° C. for 3 hours under atmosphere protection and kept warm for 1.5 hours.

[0061] The sintered magnetic core used in this embodiment helps to improve the effective magnetic permeability of the magnet itself, and its effective magnetic permeability can reach more than 88%. Among them, the raw materials of the sintered magnetic core are one or more of iron silicon chromium, iron silicon, iron silicon aluminum, and iron nickel alloy powder. The sintered magnetic core method makes the residual internal stress of the magnetic powder small after being subjected to high pressure, so its loss is relatively low. Due to the use of warm pressing molding, its density can reach about 6.0kg / m3, which is close to the density of one-piece molded inductors.

[0062] Among them, the plastic sealing process is a thermochemical reaction, so when transferring the plastic sealing material, the plastic sealing magnetic powder material must be preheated first, generally using a high-frequency preheating machine for preheating. After the plastic sealing material is placed in the mold, it is preheated for 20 to 40 seconds (set according to the requirements of the preheating machine), and the preheating temperature is 75 to 85° (the preheating temperature is the surface temperature of the mold, not the internal temperature of the composite magnetic powder).

[0063] In step 3, if Figure 1As shown, after placing the plastic-encapsulated composite magnetic powder particles 1 into the transfer injection molding mold 4, the process further includes: preheating the plastic-encapsulated composite magnetic powder particles 1, and the preheating temperature is the mold surface temperature.

[0064] In step 3, the process of placing the plastic-encapsulated composite magnetic powder particles 1 and the sintered magnetic core 2 with the wound coil 3 into the transfer injection molding mold 4 for compression molding includes:

[0065] The die punch 6 pushes the plastic-encapsulated composite magnetic powder particles 1 downward, so that the plastic-encapsulated composite magnetic powder particles 1 are softened by heat and pressure, and are pushed forward along the channel 5 of the transfer injection molding die 4;

[0066] The plastic-encapsulated composite magnetic powder particles 1 are pushed into the mold cavity containing the wound sintered magnetic core and fill the entire mold cavity, and then begin to solidify, completing the compression molding process.

[0067] The temperature of the transfer injection molding mold 4 is 170-180°C, the transfer pressure is 10-15Mpa, the transfer speed time is 5-30s, the mold clamping pressure is 20-80Mpa, and the curing time is 30-180s. This ensures that there are no voids and delaminations inside after plastic sealing, and the appearance of the body is free of defects. Due to the use of low pressure (20-80Mpa) molding pressure, the coil deformation is small and the risk of coil short circuit is small.

[0068] This embodiment can shorten the inductor molding process because the epoxy resin that can be quickly cured at high temperature is used as a binder and has high strength after curing. The epoxy resin can be quickly cured at 180°C in just 80 seconds, which greatly shortens the molding time.

[0069] The following is an implementation plan for the ratio of magnetic powder glue as shown in Table 1:

[0070] Table 1 Implementation plan for magnetic powder glue ratio

[0071]

[0072]

[0073] The performance evaluation structure after molding is shown in Table 2:

[0074] Table 2 Performance evaluation of integrated inductor after molding

[0075]

[0076] It can be seen from Table 2 that, compared with traditional compression molding, the performance of the inductor prepared by the steps in the method for preparing the transfer plastic encapsulation integrated molded inductor according to the embodiment of the present invention is more stable.

[0077] In one or more embodiments, an inductor is further provided, which is prepared by using the steps in the above-mentioned method for preparing the transfer plastic-sealed integrated inductor.

[0078] The inductor prepared by the steps in the above-mentioned transfer plastic encapsulation integrated molded inductor preparation method can be a plug-in type or a surface mount type integrated inductor, and its shape can be cylindrical, rectangular or other polyhedral structure inductor. Those skilled in the art can make specific settings according to actual conditions, which will not be described in detail here.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An iron-based alloy powder, It is characterized in that The iron-based alloy powder includes the following components by weight percentage: Fe: 75-92%, Ni: 5-10%, Si: 3.0-5.0%, B: 0.5-2%, P: 1-2%, Co: 0.1-0.5%, C: 0.5-1%, Cr: 0.5-3%, and Mn: 0.1-1%.

2. The iron-based alloy powder according to claim 1, It is characterized in that In the process of preparing the iron-based alloy powder, the component materials of the iron-based alloy powder are atomized to obtain iron-based alloy particles; and then the iron-based alloy particles are dispersed by setting high temperature and high frequency smelting and high pressure to form an iron-based alloy powder.

3. A method for preparing a transfer plastic-encapsulated integrated inductor, It is characterized in that include: The iron-based alloy powder according to any one of claims 1 to 2 is subjected to secondary coating and extrusion granulation treatment to obtain plastic-encapsulated composite magnetic powder particles; preparing a sintered magnetic core and winding a coil thereon; Placing the plastic-encapsulated composite magnetic powder particles and the sintered magnetic core with the wound coil into a transfer injection molding mold for compression molding; The inductor after compression molding is subjected to terminal stripping, tinning and folding treatment to prepare a transfer plastic-sealed integrated inductor.

4. The method for preparing the transfer plastic encapsulated integrated inductor according to claim 3, It is characterized in that The process of performing secondary coating treatment on the iron-based alloy powder comprises: Phosphoric acid, a coupling agent and nano-scale fumed silica are used to form an inorganic insulating layer on the surface of the iron-based alloy powder to obtain a first coated powder; The first coating powder is coated for the second time with a thermosetting epoxy resin layer; wherein the mass percentages of the thermosetting epoxy resin layer and the first coating powder are 3% to 10% and 90% to 97% respectively.

5. The method for preparing the transfer plastic-sealed integrated inductor according to claim 4, It is characterized in that The phenolic resin in the thermosetting epoxy resin layer 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.

6. The method for preparing the transfer plastic encapsulated integrated inductor according to claim 4, It is characterized in that The components of the thermosetting epoxy resin layer are bisphenol F epichlorohydrin polymer, 2,2'-[1,6-phenylene (1-oxymethylene)] dioxirane, amine hardener, K550 coupling agent and natural wax, and the mass percentages are 1% to 2%, 0.2% to 0.5%, 0.1% to 1%, 0.1% to 1%, and 0.1% to 1%, respectively.

7. The method for preparing the transfer plastic-sealed integrated inductor according to claim 3, It is characterized in that During the extrusion granulation process after the secondary coating of the iron-based alloy powder, the granulation screen used was 50 meshes and the fluidity was 35±5s.

8. The method for preparing the transfer plastic encapsulated integrated inductor according to claim 3, It is characterized in that In the process of preparing the sintered magnetic core, the magnetic core is sintered at 600°C to 750°C for 3 hours under atmosphere protection and kept warm for 1.5 hours.

9. The method for preparing the transfer plastic-sealed integrated inductor according to claim 3, It is characterized in that After placing the plastic-encapsulated composite magnetic powder particles into the transfer injection molding mold, the method further includes: preheating the plastic-encapsulated composite magnetic powder particles, wherein the preheating temperature is the surface temperature of the mold.

10. The method for preparing the transfer plastic encapsulated integrated inductor according to claim 3, It is characterized in that The process of placing the plastic-encapsulated composite magnetic powder particles and the sintered magnetic core with the wound coil into the transfer injection molding mold for compression molding includes: The die punch is pushed downward to squeeze the plastic-encapsulated composite magnetic powder particles, so that the plastic-encapsulated composite magnetic powder particles are softened by heat and pressure, and are pushed forward along the transfer injection molding die channel; The plastic-encapsulated composite magnetic powder particles are pushed into the mold cavity containing the wound sintered magnetic core and fill the entire mold cavity, and then begin to solidify, completing the compression molding process.

11. An inductor, It is characterized in that The inductor is prepared by the steps of the method for preparing a transfer plastic encapsulation integrated inductor as described in any one of claims 3 to 10.

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