Micro patch power inductor based on micro area 3D printing and preparation method thereof

Abstract

The application discloses a micro patch power inductor based on micro area 3D printing and a preparation method thereof, and belongs to the technical field of 3D printing micro inductor devices. The preparation method uses Fe-based soft magnetic powder as a magnetic phase raw material to prepare a 3D printing support medium; a micro area 3D printing method is used to print at least one group of coils and lead-out ends of the coils in the support medium, so that the coils and the lead-out ends are completely embedded in the support medium, and an inductor blank is formed; after the support medium and the inductor blank are separated, the inductor is prepared, the inductor is cleaned and silver-plated; the inductor after silver-plating is annealed, and a micro patch power inductor is prepared. The method can print micron-level coils, the prepared inductor has a smaller volume, can reach a wire diameter of 10 um, has a good yield, can be annealed, the magnetic permeability of the magnetic material is improved, the magnetic hysteresis loss is reduced, and the prepared inductor has higher electromagnetic performance under the same volume condition.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of 3D printing micro inductor devices, and particularly relates to a micro patch power inductor based on micro area 3D printing and a preparation method thereof. BACKGROUND

[0002] With the development of 5G electronics, the performance requirements of electronic components are also getting higher and higher. On the one hand, it requires smaller size, and on the other hand, the performance of electronic components is better than that of the same size components. For smaller volume inductance components, it is required that the selected magnetic material has higher magnetic permeability, higher saturation magnetic induction and lower loss, etc. Furthermore, the process precision of smaller volume inductance is higher, and higher precision of equipment is required.

[0003] At present, small volume inductance components are usually pre-coiled and then filled with powder and pressed. This method requires high forming pressure (500-800 Mpa), and the coil may be deformed due to excessive pressure, even short circuit, low Q and other risks, so this process also has certain disadvantages. Furthermore, the process of integrally forming inductance pre-embedded enameled wire coil limits the annealing temperature of alloy powder, which is difficult to eliminate the internal stress of inductance caused by pressing, resulting in higher loss of prepared inductance, and it is difficult to further improve the magnetic permeability of magnetic material, which also restricts the improvement of metal power inductance performance. In order to prepare smaller volume inductance, LTCC process is also used to prepare laminated patch inductance. Although the laminated patch inductance prepared by LTCC process can prepare smaller volume inductance, it is difficult to print smaller diameter coil based on printing process, and the production yield will decrease with the decrease of the size of prepared inductance due to the problems of laminated alignment and inductance magnetic phase deformation.

[0004] Therefore, a micro patch power inductor based on micro area 3D printing and a preparation method thereof are needed, which can prepare smaller volume and have higher yield. SUMMARY

[0005] In view of this, the present application aims to provide a micro patch power inductor based on micro area 3D printing and a preparation method thereof, which aims to solve at least one technical problem in the background art.

[0006] The present application is implemented as follows:

[0007] The present application comprises a preparation method of a micro patch power inductor based on micro area 3D printing, which comprises the following steps:

[0008] Fe-based soft magnetic powder is used as the raw material of magnetic phase to make 3D printing support medium;

[0009] The micro 3D printing method is used to print at least one set of coils and the leading end of the coil in the supporting medium, so that the coil and the leading end thereof are completely embedded in the supporting medium, and an inductor blank is formed;

[0010] After separating the supporting medium and the inductor blank, the inductor is manufactured, cleaned and silvered;

[0011] The inductor after silvering is annealed to obtain a micro patch power inductor.

[0012] Working principle and beneficial effects include:

[0013] 1. Compared with the prior art, especially the two existing processes, the present application is based on 3D printing, and the coil is completely embedded in the magnetic slurry by using the micro 3D printing method, so that the wire diameter of the coil can reach microns, and the minimum can reach 10 um, which cannot be realized by the prior art, so the present application can prepare a smaller volume inductor, and the overall preparation process is more convenient than the prior art, which greatly helps to improve the yield of the coil due to the existing high-precision 3D printer.

[0014] 2. Compared with the prior art, the present application prints the coil in the magnetic slurry, which not only has higher precision, but also has a larger coil column, which can fully utilize the space occupied by the wire, so that the inductor prepared has a larger saturation current, and the prior art cannot achieve a wire diameter of microns, so it cannot make the inductor to the micron level of the present application.

[0015] 3. Compared with the prior art, the coil does not need an insulating layer during printing, so high-temperature annealing treatment can be performed on the coil, so the magnetic permeability of the magnetic material in the magnetic slurry can be improved, and the magnetic hysteresis loss can be reduced, so that the electromagnetic performance is higher under the same volume condition.

[0016] Further, after separating the supporting medium and the inductor blank, the inductor is manufactured, cleaned and silvered, which specifically includes:

[0017] A cutting line is set, and the inductor blank is dried again, the temperature is set to 60-80 DEG C, and the drying time is set to 30-60 min;

[0018] The inductor blank is subjected to isostatic pressing treatment, and the pressure is set to 70-100 Mpa;

[0019] The inductor is cut along the cutting line and subjected to medium-temperature glue removal, and the temperature is set to 290-320 DEG C;

[0020] The inductor is cleaned, chamfered and silvered.

[0021] The step can not only quickly and conveniently prepare the inductor, but also eliminate internal stress of the magnetic material in the magnetic slurry, thereby improving magnetic permeability of the magnetic material, reducing hysteresis loss, and making the inductor have lower loss.

[0022] Further, the manufacturing step of the 3D-printed support medium comprises:

[0023] The Fe-based soft magnetic powder is pre-annealed;

[0024] The Fe-based soft magnetic powder after the annealing treatment is passivated;

[0025] The Fe-based soft magnetic powder after the passivation treatment is mixed, stirred and ball milled with a dispersant, a binder, a curing agent, a plasticizer and an organic solvent until the Fe-based soft magnetic powder is uniformly dispersed in the mixed solution, and a magnetic slurry is obtained after filtration;

[0026] The magnetic slurry is poured into a mold for printing, leveled and placed in a printing area as a 3D-printed support medium.

[0027] The step can eliminate internal stress of the Fe-based soft magnetic powder through annealing treatment, and the Fe-based soft magnetic powder passivated and mixed with various reagents can obtain a magnetic slurry, which can increase resistivity as a magnetic phase, thereby reducing eddy current loss. The magnetic slurry has excellent fluidity and low sintering shrinkage, is an excellent support medium for 3D-printed coils, can better match the printed coils, and reduces the risk of short circuit or open circuit of the inductor.

[0028] Further, the Fe-based soft magnetic powder is selected from at least one of FeSiCr powder, carbonyl iron powder, iron-based amorphous powder and iron-based nanocrystalline powder; and the D50 of the Fe-based soft magnetic powder is between 10 and 30 microns.

[0029] Further, the binder is selected from at least one of organic silicone resin, epoxy resin and water glass, and the addition amount is 3-13wt% of the weight of the Fe-based soft magnetic powder;

[0030] The plasticizer is phthalic acid, and the addition amount is 1-6wt% of the weight of the Fe-based soft magnetic powder;

[0031] The organic solvent is selected from at least one of ethanol, ethyl acetate and n-propyl acetate.

[0032] Further, the passivation treatment specifically comprises: mixing the Fe-based soft magnetic powder after the annealing treatment with an ethanol phosphate or ethanol nitrate solution uniformly and drying at low temperature, so that the surface of the Fe-based soft magnetic powder is covered with / loaded with a passivation film formed by phosphoric acid or nitric acid, and the addition amount of the ethanol phosphate or ethanol nitrate solution is 0.5-2wt% of the weight of the Fe-based soft magnetic powder.

[0033] Further, the solid content of the magnetic slurry is 65-85%, and the viscosity is 2000-15000 Pa S.

[0034] Further, the pre-annealing treatment of the Fe-based soft magnetic powder and the annealing treatment of the inductor after silver plating are both carried out in a nitrogen protective atmosphere or vacuum.

[0035] Further, the 3D printing equipment using the micro 3D printing method has a precision of nanometer or micrometer level; and the material of the coil is conductive silver paste.

[0036] The application also includes a micro patch power inductor based on micro 3D printing prepared by the above method.

[0037] The inductor prepared by the method has the advantages of smaller size, can achieve a wire diameter of 10 um, and has a good yield. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The flow chart of the preparation method of the micro patch power inductor based on micro 3D printing of the application is shown in the figure.

[0039] Figure 2 The 3D printing schematic diagram of the application is shown in the figure.

[0040] It is shown that 1 is a support medium, and 2 is a coil. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in the application belong to the scope of protection of the application.

[0042] Those skilled in the art should understand that in the disclosure of the application, the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the above terms cannot be understood as a limitation of the application.

[0043] A preparation method of a micro patch power inductor based on micro 3D printing, comprising the following steps:

[0044] S100, using Fe-based soft magnetic powder as a magnetic phase raw material to prepare a 3D printing support medium.

[0045] (1) pre-annealing Fe-based soft magnetic powder;

[0046] In this step, the Fe-based soft magnetic powder is first pre-annealed to reduce the internal stress of the Fe-based soft magnetic powder. The pre-annealing temperature and time parameters are adjusted according to the different Fe-based soft magnetic powders.

[0047] The Fe-based soft magnetic powder is selected from at least one of FeSiCr powder, carbonyl iron powder, iron-based amorphous powder, and iron-based nanocrystalline powder. The D50 of the Fe-based soft magnetic powder is set to 10-30 μm.

[0048] The FeSiCr powder is annealed at a temperature of 700-900 °C for 2-4 h. The carbonyl iron powder is annealed at a temperature of 400-500 °C for 1-3 h. The iron-based amorphous powder is annealed at a temperature of 400-450 °C for 1 h. The iron-based nanocrystalline powder is annealed at a temperature of 500-550 °C for 1 h. The pre-annealing is performed in nitrogen or vacuum.

[0049] The Fe-based soft magnetic powder is a gas-atomized spherical powder, and the prepared magnetic phase density distribution is uniform. In specific implementation, if multiple Fe-based soft magnetic powders are used, they can be annealed separately and then mixed.

[0050] (2) passivating the Fe-based soft magnetic powder after annealing;

[0051] In this step, the Fe-based soft magnetic powder is mixed with an ethanol phosphoric acid solution and dried at a low temperature (e.g., 80 °C) to complete the passivation of the Fe-based soft magnetic powder. The amount of the ethanol phosphoric acid solution added is 0.5-2 wt% of the weight of the Fe-based soft magnetic powder. In addition, an ethanol nitric acid solution can also be used. Passivation refers to forming a passivation film on the surface of the powder by using phosphoric acid or nitric acid to increase the resistivity of the powder particles.

[0052] (3) mixing and stirring the Fe-based soft magnetic powder after passivation with a dispersant, a binder, a curing agent, a plasticizer, and an organic solvent until the Fe-based soft magnetic powder is uniformly dispersed in the mixed solution, and then filtering to obtain a magnetic slurry;

[0053] In this step, the ball milling time is more than 10 h. In order to obtain a mixed solution in which the Fe-based soft magnetic powder is uniformly dispersed, the mixed solution at this time has formed a slurry.

[0054] The binder includes at least one of silicone resin, epoxy resin and water glass, the adding amount is 3-13wt% of the weight of the Fe-based soft magnetic powder, the plasticizer is phthalic acid, the adding amount is 1-6wt% of the weight of the Fe-based soft magnetic powder, the organic solvent is at least one of ethanol, ethyl acetate and n-propyl acetate, the solid content of the magnetic slurry prepared is 65-85%, and the viscosity is 2000-15000Pa·S. The binder selected in the application has the characteristics of high temperature resistance, so that the magnetic slurry can have good mechanical strength after solidification.

[0055] The dispersant and the curing agent can be any material allowed in the art, and the adding amount can be adjusted according to actual needs (generally 0.1-2wt%), which is not specifically limited here. For example, the dispersant can be a polyacrylic acid dispersant, an ammonium citrate salt or the like, and the curing agent can be an epoxy curing agent.

[0056] In this step, the mixed solution is filtered by a 120-mesh screen to obtain the magnetic slurry, so as to ensure that there are fewer agglomerates in the mixed solution.

[0057] (4) Pour the magnetic slurry into a mold for printing, scrape it flat, and place it in the printing area as a support medium for 3D printing.

[0058] The magnetic slurry prepared in the above steps can first eliminate the internal stress of the Fe-based soft magnetic powder through annealing treatment, so that the Fe-based soft magnetic powder can increase the resistivity as a magnetic phase, thereby reducing the eddy current loss. The passivation treatment of the Fe-based soft magnetic powder and the mixing with various reagents can obtain the magnetic slurry, which has excellent fluidity and low sintering shrinkage, is an excellent support medium for 3D printed coils, can better match the printed coils, and reduces the risk of short circuit or open circuit of inductors.

[0059] S200, at least one group of coils and the lead-out end of the coil are printed in the support medium by using a micro 3D printing method, so that the coil and the lead-out end are completely embedded in the support medium, and an inductor blank is formed.

[0060] In this step, the printing parameters of the 3D printer are adjusted, the program corresponding to the coil model is imported, and the 3D printer is started to print. The print head of the 3D printer prints the coil and the coil lead-out end in the magnetic slurry according to the designed position from bottom to top. After printing is completed, an inductor blank is formed, as shown in Figure 2 The printed coil 2 is completely embedded in the support medium 1 made of the magnetic slurry.

[0061] The printing precision of the 3D printer of the application is nanometer or micrometer, and the micro 3D printing method can also be called micro-nano 3D printing technology. The micro-nano 3D printing equipment is prior art in the field of 3D printing, so the structure and principle thereof will not be described in detail.

[0062] It is worth mentioning that, in the present application, the metal material of the printing coil is conductive silver paste, which has good conductivity and good fluidity, and the resistivity after solidification can reach 2-4*10 -6 Ω*cm, which can be very stably extruded from a 10um 3D printing head.

[0063] S300, after separating the support medium and the inductor blank, the inductor is made, cleaned and silvered.

[0064] (1) Set the cutting line, and then dry the inductor blank;

[0065] After printing all the coils, print the cutting line, which can facilitate the subsequent cutting of the coil blank from the entire magnetic paste, as a plurality of coils are usually printed at one time;

[0066] The inductor blank formed by the support medium with the coil is dried at a temperature of 60-80℃ for 30-60min, which is mainly to solidify the magnetic material and the coil, so that the magnetic material and the coil form a block, and other materials such as organic solvent ethanol are removed. The block is the inductor blank, which facilitates subsequent cutting operation to remove residual organic solvents such as ethanol. At this time, the support medium is left with soft magnetic phase and organic resin, plasticizer and dispersant, etc.

[0067] (2) The inductor blank is subjected to isostatic pressing treatment at a pressure of 70-100Mpa, which is to increase the density of the block.

[0068] (3) The inductor is cut along the cutting line and subjected to medium-temperature glue removal at a temperature of 290-320℃, and then the glue wrapped outside the inductor is removed.

[0069] (4) The inductor is chamfered and silvered.

[0070] The surface of the glue-removed inductor is cleaned, and the inductor is chamfered and silvered, where silvering is also called silvering. The currently widely used silvering process is silver spraying, that is, the silver paste is in a mist state by high pressure, and is sprayed on the part to be electroplated. Silvering can change the surface properties or size of the substrate, improve the corrosion resistance of metal parts in the use environment, improve the working performance of the parts, such as hardness, wear resistance, conductivity, electromagnetic property, heat resistance, etc., so as to improve the performance of the inductor

[0071] S400, the inductor after silvering is annealed to obtain a micro-patch power inductor.

[0072] In this step, the temperature of the annealing treatment is 450-550 DEG C, and the time is 1h. The purpose of the annealing treatment is mainly to remove the stress generated in the magnetic material in the S202 step, so that the magnetic material has good performance again.

[0073] The inductor generally comprises a coil, end electrodes and a magnetic body part, so the end electrodes and the coil are directly printed in the printing process, and the magnetic body part is formed by wrapping the magnetic material in the magnetic slurry around the coil after solidification.

[0074] The annealing treatment is carried out in a vacuum or nitrogen environment, so that the inductor has high magnetic permeability, which is 1.5-3 times that before annealing, and the magnetic loss of the inductor is significantly reduced after annealing.

[0075] In summary, the method of the application is simple, can greatly improve the production efficiency of the inductor, is conducive to reducing the production cost, the power inductor prepared by the method can be high-temperature annealed, the magnetic permeability of the alloy powder can be improved, and the loss of the inductor can be reduced, the wire diameter of the printed coil can be between 10-200um, that is, the minimum printed wire diameter can be 10um, and the printing precision is controllable.

[0076] Example 1

[0077] A preparation method of a micro patch power inductor based on micro area 3D printing, comprising the following steps:

[0078] 1. Fe-based soft magnetic powder is used as raw material to prepare 3D printed support medium

[0079] FeSiCr powder (D50=20um, magnetic permeability is 40, and saturation magnetic induction Bs value is 1.65T) is pre-annealed at 700 DEG C for 4h in a vacuum;

[0080] 0.5wt% of phosphoric acid ethanol solution is added to the powder, the two are fully stirred and mixed, and then dried at 80 DEG C, so that the FeSiCr powder forms a passivation film;

[0081] 1wt% of polyacrylic acid dispersant, 3wt% of silicone resin, 6wt% of phthalic acid, and 1wt% of epoxy curing agent are added to the treated FeSiCr powder in ethanol, and the mixture is uniformly stirred and ball milled for 12h to obtain a mixed solution in which the Fe-based soft magnetic powder is uniformly dispersed, the solid content of the magnetic slurry is 65%, and the viscosity is about 8000Pa·S;

[0082] Then, the mixed solution is filtered by using a 120 mesh screen to obtain the magnetic slurry;

[0083] Finally, the magnetic slurry is poured into a mold for printing, leveled, and placed in a printing area as a 3D printed support medium.

[0084] 2. Printing at least one set of coils and the lead-out end of the coil in the support medium by using the micro-area 3D printing method, so that the coil and the lead-out end thereof are completely embedded in the support medium, to form an inductor blank.

[0085] The conductive silver paste is used as the material for printing the coil, the printing parameters of the nanoscale 3D printer are adjusted, the program corresponding to the coil model is imported, and the 3D printer is started to print. The print head of the 3D printer prints the coil and the lead-out end of the coil in the support medium made of magnetic slurry according to the designed position from bottom to top. After printing is completed, the inductor blank is formed, and the wire diameter of the coil is 10 μm.

[0086] 3. After separating the support medium and the inductor blank, the inductor is manufactured, cleaned and silverized.

[0087] After all the coils are printed, a cutting line is printed, and the inductor blank formed by the support medium with the coils is dried at a temperature of 70°C for 45 min;

[0088] The inductor blank is subjected to isostatic pressing at a pressure of 80 MPa;

[0089] The inductor is cut along the cutting line, and then degassing is performed at 300°C;

[0090] After the inductor is cleaned, chamfering and silverizing are performed on the inductor.

[0091] 4. The silverized inductor is subjected to annealing treatment under a nitrogen protective atmosphere, the annealing treatment temperature is 700°C, and the time is 2 h, to obtain a micro-patch power inductor.

[0092] The size of the inductor obtained is L*W*H = 2.0*1.2*1.0 mm, the maximum DCR design requirement is 95 mΩ, and the inductance is 1.0±20% uH.

[0093] Example 2

[0094] A preparation method of a micro-patch power inductor based on micro-area 3D printing, comprising the following steps:

[0095] 1. Fe-based soft magnetic powder is used as raw material to manufacture a 3D printed support medium.

[0096] Under a nitrogen protective atmosphere, the iron-based amorphous powder (D50 = 10 μm, permeability of 22, and saturation magnetic induction Bs value of 1.6 T) is subjected to pre-annealing treatment at 420°C in vacuum for 1 h;

[0097] Then 1wt% of phosphoric acid ethanol solution is added to the powder, and the two are fully stirred and mixed, and then dried at 80°C, so that the iron-based amorphous powder forms a passivation film;

[0098] 1wt% polyacrylic dispersant, 10wt% epoxy resin, 3wt% phthalic acid, 1wt% epoxy curing agent and the treated iron-based amorphous powder were added into ethanol solvent, mixed and stirred uniformly and ball milled for 12h to obtain a mixed solution with Fe-based soft magnetic powder uniformly dispersed, and a magnetic slurry with a solid content of 75% and a viscosity of about 12000Pa·S was prepared;

[0099] Then the mixed solution was filtered by a 120 mesh screen to obtain a magnetic slurry;

[0100] Finally, the magnetic slurry was poured into a mold for printing, leveled and placed in the printing area as a support medium for 3D printing.

[0101] 2. At least one group of coils and the lead-out end of the coil were printed in the support medium by using a micro-area 3D printing method, so that the coil and the lead-out end thereof were completely embedded in the support medium to form an inductor blank.

[0102] The conductive silver paste was used as the material for printing the coil, the printing parameters of the nanoscale 3D printer were adjusted, the program corresponding to the coil model was imported, and the 3D printer was started to print. The print head of the 3D printer printed the coil and the lead-out end of the coil in the support medium made of the magnetic slurry according to the designed position from bottom to top. After printing was completed, the inductor blank was formed, and the wire diameter of the coil was 10μm.

[0103] 3. After the support medium and the inductor blank were separated, the inductor was made, cleaned and silvered.

[0104] After all the coils were printed, a cutting line was printed, and the inductor blank formed by the support medium with the coils was dried at a temperature of 60℃ for 60min;

[0105] The inductor blank was subjected to isostatic pressing at a pressure of 90Mpa;

[0106] The inductor was cut along the cutting line, and then degassing was performed at 320℃;

[0107] After the inductor was cleaned, chamfering and silvering were performed.

[0108] 4. The inductor after silvering was subjected to annealing treatment under a nitrogen protective atmosphere, the annealing temperature was 450℃, and the time was 1h, and a micro patch power inductor was prepared.

[0109] The prepared inductor has a size of L*W*H=2.0*1.2*1.0mm, a maximum DCR design requirement of 95mΩ, and an inductance of 1.0±20%uH.

[0110] Example 3

[0111] A preparation method of a micro patch power inductor based on micro area 3D printing, comprising the following steps:

[0112] 1. Fe-based soft magnetic powder is used as raw material to make 3D printing support medium.

[0113] Under the protection of nitrogen atmosphere, the iron-based nanocrystalline powder (D50 = 10 μm, magnetic permeability of 22, and saturation magnetic induction Bs value of 1.25 T) is pre-annealed in vacuum at 550°C for 1 h;

[0114] Then 2wt% nitric acid ethanol solution is added to the powder, and the mixture is stirred and mixed thoroughly, and then dried at 80°C to form a passivation film on the iron-based amorphous powder;

[0115] 1wt% polyacrylic dispersant, 13wt% water glass, 1wt% phthalic acid and 1wt% epoxy curing agent are added to the treated iron-based nanocrystalline powder in n-propyl acetate solvent, and the mixture is uniformly stirred and ball milled for 12 h to obtain a mixed solution with uniformly dispersed Fe-based soft magnetic powder, and the solid content of the magnetic slurry is 85% and the viscosity is about 15000 Pa·S;

[0116] Then the mixed solution is filtered by a 120 mesh screen to obtain the magnetic slurry;

[0117] Finally, the magnetic slurry is poured into a mold for printing, leveled and placed in the printing area as the 3D printing support medium.

[0118] 2. At least one group of coils and the lead-out end of the coil are printed in the support medium by using the micro area 3D printing method, so that the coil and the lead-out end are completely embedded in the support medium to form an inductor blank.

[0119] The conductive silver paste is used as the material for printing the coil, the printing parameters of the nanoscale 3D printer are adjusted, the corresponding coil model program is imported, and the 3D printer is started to print. The print head of the 3D printer prints the coil and the coil lead-out end in the support medium made of magnetic slurry according to the designed position from bottom to top. After printing is completed, the inductor blank is formed, and the wire diameter of the coil is 10 μm.

[0120] 3. After separating the support medium and the inductor blank, the inductor is made, cleaned and silverized.

[0121] After all the coils are printed, a cutting line is printed, and the inductor blank formed by the support medium with the coil is dried at a temperature of 80°C for 30 min;

[0122] The inductor blank is subjected to isostatic pressing at a pressure of 70 Mpa;

[0123] Cut the inductor along the cutting line, and then perform degassing at 290℃;

[0124] After cleaning the inductor, chamfer the inductor and silver the ends.

[0125] 4. Anneal the inductor after silvering the ends under a nitrogen atmosphere, at a temperature of 450℃ for 1h, to obtain a micro-patch power inductor.

[0126] The inductor obtained has dimensions L*W*H = 2.0*1.2*1.0mm, a DCR design requirement of a maximum of 95mΩ, and an inductance of 1.0±20%uH.

[0127] Example 4

[0128] A method for preparing a micro-patch power inductor based on micro-zone 3D printing, comprising the following steps:

[0129] 1. Use Fe-based soft magnetic powder as raw material to make a 3D printing support medium.

[0130] In a vacuum environment, pre-anneal the carbonyl iron powder (D50 = 5μm, magnetic permeability of 37, and saturation magnetic induction Bs value of 1.65T) in a vacuum at 450℃ for 2h;

[0131] Then add 2wt% nitric acid ethanol solution to the powder, mix the two thoroughly, and dry at 80℃ to form a passivation film on the carbonyl iron powder;

[0132] Add 1wt% polyacrylic acid dispersant, 8wt% silicone resin, 1wt% phthalic acid, and 1wt% epoxy curing agent to the treated carbonyl iron powder in ethyl acetate solvent, mix and stir uniformly, and ball mill for 12h to obtain a mixed solution of uniformly dispersed Fe-based soft magnetic powder, with a solid content of the magnetic slurry of 85% and a viscosity of about 15000Pa·S;

[0133] Then filter the mixed solution using a 120-mesh silk screen to obtain a magnetic slurry;

[0134] Finally, pour the magnetic slurry into a mold for printing, scrape it flat, and place it in the printing area as a 3D printing support medium.

[0135] 2. Use a micro-zone 3D printing method to print at least one set of coils and the leads of the coils in the support medium, so that the coils and their leads are completely embedded in the support medium, forming an inductor blank.

[0136] The conductive silver paste is used as the material of the printed coil, the printing parameters of the nanoscale 3D printer are adjusted, the program corresponding to the coil model is imported, the 3D printer is started to print, the printing head of the 3D printer prints the coil and the coil lead-out end in the support medium made of the magnetic paste according to the designed position from bottom to top, and the inductor blank is formed after the printing is completed, and the wire diameter of the coil is 10 μm.

[0137] 3. After separating the support medium and the inductor blank, the inductor is manufactured, the inductor is cleaned, and silver is connected to the inductor.

[0138] After all the coils are printed, the cutting line is printed, the inductor blank formed by the support medium with the coils is dried at a temperature of 80 ℃, and the drying time is 30 min;

[0139] The inductor blank is subjected to isostatic pressing at a pressure of 70 MPa;

[0140] The inductor is cut along the cutting line, and then degassing is performed at 290 ℃;

[0141] After the inductor is cleaned, the inductor is chamfered and silver is connected to the inductor.

[0142] 4. The inductor to which silver is connected is subjected to annealing treatment under a nitrogen protective atmosphere, the annealing treatment is performed at a temperature of 700 ℃ for 1 h, and a micro patch power inductor is prepared.

[0143] The prepared inductor has a size of L*W*H = 2.0*1.2*1.0 mm, a maximum DCR design requirement of 95 mΩ, and an inductance of 1.0 ± 20% uH.

[0144] Example 5

[0145] A preparation method of a micro patch power inductor based on micro area 3D printing, comprising the following steps:

[0146] 1. Fe-based soft magnetic powder is used as raw material to manufacture a 3D printed support medium.

[0147] Under a nitrogen protective atmosphere, the iron-based amorphous powder (D50 = 10 μm, permeability of 22, and saturation magnetic induction Bs value of 1.6 T) is subjected to pre-annealing treatment in a vacuum at 450 ℃ for 1 h, and the iron-based nanocrystalline powder (D50 = 20 μm, permeability of 22, and saturation magnetic induction Bs value of 1.25 T) is subjected to pre-annealing treatment in a vacuum at 500 ℃ for 1 h, and the two are mixed to form Fe-based soft magnetic mixed powder;

[0148] Then, 1.5 wt% of an ethanol solution of phosphoric acid is added to the powder, the two are fully stirred and mixed, and then dried at a temperature of 80 ℃, so that the Fe-based soft magnetic mixed powder forms a passivation film;

[0149] 1wt% polyacrylic dispersant, 8wt% silicone resin, 23wt% phthalic acid, 1wt% epoxy curing agent and the treated Fe-based soft magnetic mixed powder are added into ethanol solvent, mixed and stirred uniformly and ball milled for 13h to obtain a mixed solution in which the Fe-based soft magnetic powder is uniformly dispersed, a magnetic slurry is prepared, the solid content of which is 80% and the viscosity is about 13500Pa·S;

[0150] Then the mixed solution is filtered by using a 120-mesh screen to obtain a magnetic slurry;

[0151] Finally, the magnetic slurry is poured into a mold for printing, leveled and placed in a printing area as a support medium for 3D printing.

[0152] 2. At least one group of coils and the lead-out ends of the coils are printed in the support medium by using a micro-area 3D printing method, so that the coils and the lead-out ends thereof are completely embedded in the support medium to form an inductor blank.

[0153] The conductive silver paste is used as the material for printing the coils, the printing parameters of the nanoscale 3D printer are adjusted, the program corresponding to the coil model is imported, and the 3D printer is started to print. The print head of the 3D printer prints the coils and the lead-out ends of the coils in the support medium made of the magnetic slurry according to the designed position from bottom to top. After printing is completed, the inductor blank is formed, and the wire diameter of the coil is 10μm.

[0154] 3. After the support medium and the inductor blank are separated, the inductor is made, cleaned and silverized.

[0155] After all the coils are printed, a cutting line is printed, and the inductor blank formed by the support medium with the coils is dried at a temperature of 75℃ for 45min;

[0156] The inductor blank is subjected to isostatic pressing at a pressure of 80Mpa;

[0157] The inductor is cut along the cutting line, and then degassing is performed at 300℃.

[0158] After the inductor is cleaned, chamfering is performed and silverizing is performed.

[0159] 4. The inductor after silverizing is subjected to annealing treatment under a nitrogen protective atmosphere, the temperature of the annealing treatment is 550℃, and the time is 1h to obtain a micro-patch power inductor.

[0160] The size of the inductor obtained is L*W*H=2.0*1.0*1.0mm, the maximum DCR design requirement is 95mΩ, and the inductance is 1.0±20%uH.

[0161] The inductor prepared by the method of the embodiments of the present application has the advantages of smaller volume, can reach a wire diameter of 10 um, and has a good yield. Compared with the LTCC process, the process is simple and has high precision; on the other hand, the minimum size of the prepared power inductor can be less than 1 mm, and the height is about 0.5 mm. The inductor can be widely applied to mobile phones, notebooks, tablet computers and wearable electronics and the like.

[0162] Comparative Example 1

[0163] The difference from Example 2 is that the pre-annealing process step of the Fe-based soft magnetic powder is reduced, and the others are the same as Example 2, and the micro patch power inductor is prepared.

[0164] Comparative Example 2

[0165] The difference from Example 2 is that the passivation process step of the Fe-based soft magnetic powder is reduced, and the others are the same as Example 2, and the micro patch power inductor is prepared.

[0166] Comparative Example 3

[0167] The difference from Example 2 is that the annealing process step of the inductor is reduced, and the others are the same as Example 2, and the micro patch power inductor is prepared.

[0168] The performances of the micro patch power inductors prepared in Examples 1 to 5 and Comparative Examples 1 to 3 are compared, and the results are shown in Table 1.

[0169] Table 1

[0170] Sample L value / uH (1.0 ± 20%) Saturation current / A DCR / mΩ Temperature rise current / A Example 1 1.15 3.9 85 3.2 Example 2 0.84 3.0 83 5.1 Example 3 0.82 2.8 85 5.9 Example 4 1.18 3.8 86 3.0 Example 5 0.79 2.5 85 3.1 Comparative Example 1 1.10 3.9 86 2.5 Comparative Example 2 0.88 3.1 85 5.0 Comparative Example 3 0.60 3.4 86 4.1 Commercially available inductors 0.97 3.6 88 2.4

[0171] The performance of a commercially available inductor is taken as a comparative example, which is a power inductor of Murata Electronics, model DFE201210U-1R0M, the magnetic phase material is prepared from metal alloy magnetic powder, the wire is copper wire, and it is a product manufactured by a traditional method.

[0172] As can be seen, Table 1 lists the performances of the products prepared in the present embodiments and the commercially available inductors. As can be seen from Table 1, the power inductor prepared in the embodiments of the present application can meet the basic requirements of the same series of products. It can be seen that the DCR value of the inductor prepared by the method can be lower, and the temperature rise current of the inductor is higher than that of the inductor of model 201210U-1R0 of Murata Electronics, which indicates that the inductor prepared by the method has lower loss.

[0173] From the comparison between example 2 and comparative example 1 in table 1, it can be seen that when the support medium is prepared, the support medium prepared by pre-annealing the magnetic phase raw material (Fe-based soft magnetic powder) has lower inductance loss DCR when the power inductor is prepared, which effectively avoids the risk of short circuit or open circuit that reduces the inductance. From the comparison between example 2 and comparative examples 2-3, it can be seen that after the passivation treatment and inductance annealing treatment of the Fe-based soft magnetic powder when the support medium is prepared, the inductance L value is significantly increased, and the inductance loss DCR is lower.

[0174] The power inductor prepared by the method can meet the requirements of miniaturization and large current of the power inductor. Compared with the molded inductor, the inductor magnetic phase density of the method is low, and the inductor wire needs to be designed to use silver paste with smaller DCR, and the number of turns is appropriately increased to meet the inductance requirement. However, overall, the present application provides a new process method, which can prepare smaller inductors and has extremely high controllable precision, and can realize the printing of wire with micron-level diameter, which is of great significance for the development of the prepared inductor in the direction of miniaturization.

[0175] The part of the present application not described in detail is the prior art, so the present application does not describe it in detail.

[0176] It can be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of one element can be one, and in another embodiment, the number of the element can be multiple, and the term "one" cannot be understood as a limitation on the number.

[0177] Although professional terms are used more frequently in this paper, the possibility of using other terms is not excluded. The use of these terms is only to facilitate the description and explanation of the essence of the present application; any interpretation as any additional limitation is contrary to the spirit of the present application.

[0178] The present application is not limited to the above-mentioned best embodiment, and anyone can derive other various forms of products under the inspiration of the present application, but regardless of any change in shape or structure, any technical solution with the same or similar technical solution as the present application falls within the protection scope of the present application.

Claims

1. A method for preparing a micro patch power inductor based on micro area 3D printing, characterized in that, The preparation method comprises the following steps: S1, using Fe-based soft magnetic powder as a magnetic phase raw material to prepare a 3D printing support medium; the preparation step comprises: pre-annealing the Fe-based soft magnetic powder; passivating the Fe-based soft magnetic powder after the annealing treatment; mixing and stirring the Fe-based soft magnetic powder after the passivation treatment with a dispersing agent, a binder, a curing agent, a plasticizer and an organic solvent until the Fe-based soft magnetic powder is uniformly dispersed in the mixed solution, filtering to obtain a magnetic slurry, the solid content of the magnetic slurry being 65-85%, and the viscosity being 2000-15000 Pa·S; pouring the magnetic slurry into a mold for printing, scraping it flat and placing it in a printing area as a 3D printing support medium; S2, printing at least one group of coils and the lead-out ends of the coils in the support medium by using a micro-area 3D printing method, so that the coils and the lead-out ends thereof are completely embedded in the support medium, forming an inductor blank; S3, setting a cutting line, drying the inductor blank again, performing isostatic pressing on the inductor blank, cutting the inductor along the cutting line and performing medium-temperature glue removal, cleaning the inductor and silver plating the ends thereof; S4, annealing the inductor after the silver plating to obtain a micro-patch power inductor; the annealing temperature is 450-550 DEG C.

2. The method according to claim 1, wherein, The drying temperature of the inductor blank is set to 60-80 DEG C, and the drying time is set to 30-60 min; The pressure of the isostatic pressing is set to 70-100 Mpa; The temperature of the medium-temperature glue removal is set to 290-320 DEG C.

3. The method of claim 1, wherein the micro patch power inductor is prepared based on micro area 3D printing. The Fe-based soft magnetic powder is selected from at least one of FeSiCr powder, carbonyl iron powder, iron-based amorphous powder and iron-based nanocrystalline powder; the D50 of the Fe-based soft magnetic powder is between 10-30 mu m.

4. The method of claim 1, wherein the micro patch power inductor is prepared based on micro area 3D printing. The binder is selected from at least one of organic silicon resin, epoxy resin and water glass, and the addition amount is 3-13 wt% of the weight of the Fe-based soft magnetic powder; The plasticizer is phthalic acid, and the addition amount is 1-6 wt% of the weight of the Fe-based soft magnetic powder; The organic solvent is selected from at least one of ethanol, ethyl acetate and n-propyl acetate.

5. The method of claim 1, wherein the micro patch power inductor is prepared based on micro area 3D printing. The passivation treatment specifically comprises: mixing the Fe-based soft magnetic powder after the annealing treatment with a phosphoric acid ethanol or nitric acid ethanol solution, uniformly drying at low temperature, and the addition amount of the phosphoric acid ethanol or nitric acid ethanol solution being 0.5-2 wt% of the Fe-based soft magnetic powder.

6. The method of claim 1, wherein the micro patch power inductor is prepared based on micro area 3D printing. The pre-annealing treatment of the Fe-based soft magnetic powder and the annealing treatment of the inductor after the silver plating are both performed in a nitrogen protection atmosphere or vacuum.

7. The method according to any one of claims 1 to 6, wherein the method is a method for fabricating a micro patch power inductor based on micro 3D printing. The 3D printing equipment using the micro-area 3D printing method has a precision of nanometer or micrometer level; and the material of the coil is conductive silver paste.

8. A micro patch power inductor based on microzone 3D printing, characterized in that, A micro-patch power inductor is prepared by using the micro-area 3D printing-based micro-patch power inductor preparation method in any one of claims 1-7.

Images