Molded inductor and method of manufacture

Abstract

The application provides a molded inductor and a preparation method thereof. The preparation method comprises the following steps: filling first magnetic powder and second magnetic powder into a first mold cavity in sequence to obtain a magnetic core seat; sleeving a coil conductor on a middle column; folding two ends of the coil conductor to a side of a bottom plate away from the middle column; performing post-processing on the two ends of the coil conductor to form electrodes; and placing the magnetic core seat with the sleeved coil conductor into a second mold cavity, filling magnetic core cover magnetic powder into the second mold cavity, and performing hot pressing to obtain the molded inductor. The process flow of the preparation method is simple, and the inductance value of the obtained molded inductor is high and the direct current resistance is low.

Description

Technical Field

[0001] The present invention relates to the technical field of inductors, and particularly to a molded inductor and a preparation method thereof. Background Art

[0002] An inductor is made by winding one or more sets of coil conductors on a magnetic material. When a changing current flows through the coil, according to the law of electromagnetic induction, certain eddy current losses will inevitably occur.

[0003] Generally, during the preparation of an inductor, the magnetic powder used for the inductor is subjected to an insulation passivation treatment to block the eddy current path. Due to the small particle size of the magnetic powder itself, the passivation treatment is difficult, and problems such as unevenness, easy shedding, and poor aging resistance are likely to occur. To achieve the insulation purpose, a thickness of dozens to hundreds of nanometers usually needs to be formed, resulting in a significant reduction in the magnetic permeability of the magnetic material.

[0004] On the other hand, the electrodes of the molded inductor are extremely close to the magnetic powder in terms of distance, which requires high voltage breakdown resistance performance of the magnetic powder. Generally, the higher the breakdown voltage of the magnetic powder, the lower its magnetic permeability. In the case of low magnetic permeability, in order to obtain the same inductance, the number of turns of the coil winding will be more, which will inevitably increase the DC resistance of the inductor and cause an increase in inductor loss. Summary of the Invention

[0005] The main purpose of the present invention is to solve the deficiencies of the prior art, and provide a molded inductor and a preparation method thereof with a simple process flow, high inductance value, and low DC resistance.

[0006] The present invention provides a molded inductor and a preparation method thereof in the first aspect, which includes:

[0007] S100: Fill the first magnetic powder and the second magnetic powder into a preset first mold cavity in sequence and perform molding to obtain a magnetic core base, wherein the magnetic core base includes a middle column and a bottom plate connected to each other;

[0008] S200: Sleeve a preset coil conductor on the middle column, turn the two ends of the coil conductor to the side of the bottom plate away from the middle column, and perform post-treatment on the two ends of the coil conductor to form electrodes;

[0009] S300: Place the magnetic core base sleeved with the coil conductor into a preset second mold cavity, fill the preset magnetic core cover magnetic powder into the second mold cavity, and perform hot pressing to obtain a molded inductor;

[0010] Wherein, the types of the first magnetic powder, the second magnetic powder, and the magnetic core cover magnetic powder are different.

[0011] Preferably, symmetric notches are provided on both sides at one end of the bottom plate, the bottom plate has a "convex" structure, and the magnetic core cover magnetic powder includes a third magnetic powder and a fourth magnetic powder.

[0012] Preferably, S300 includes:

[0013] S301: Place the magnetic core holder with the coil conductor sleeved into the preset second mold cavity;

[0014] S302: Fill the two gaps in the base plate with the third magnetic powder until the two gaps are completely filled;

[0015] S303: Then fill the second mold cavity with the fourth magnetic powder until it covers the coil conductor;

[0016] S304: Perform hot pressing operation on the second mold cavity to obtain a molded inductor.

[0017] Preferably, the base plate is made of a first magnetic powder and a second magnetic powder. The first magnetic powder is disposed on the side of the base plate away from the central column. The central column is made of a second magnetic powder. The magnetic permeability of the first magnetic powder is lower than that of the second magnetic powder.

[0018] Preferably, the first magnetic powder accounts for 5% to 80% of the composition of the base plate.

[0019] Preferably, the fourth magnetic powder accounts for 10% to 99% of the composition of the magnetic core cover.

[0020] Preferably, the third magnetic powder is disposed on one side adjacent to the electrode, and the magnetic permeability of the third magnetic powder is lower than that of the fourth magnetic powder.

[0021] Preferably, the first magnetic powder, the second magnetic powder, the third magnetic powder, and the fourth magnetic powder are all subjected to insulation passivation treatment and have a resistivity ≥100Ω·m.

[0022] Preferably, the magnetic powder in the magnetic core cover includes a third magnetic powder or a fourth magnetic powder.

[0023] In a second aspect, the present invention provides a molded inductor prepared using the molding inductor and preparation method described in any of the preceding claims.

[0024] The beneficial effects of this invention are as follows:

[0025] ① The magnetic core holder and / or magnetic core cover are made of two different types of magnetic powder, which can improve the inductance value compared to only making a single layer of magnetic powder;

[0026] ②Based on the principle of induced current generation, placing high-permeability magnetic powder at a position far from the electrode can effectively reduce the withstand voltage breakdown requirement of the magnetic powder.

[0027] ③ To achieve the same permeability: By using two different types of magnetic powder, compared to using only a single type of magnetic powder, the amount of magnetic powder used and / or the number of coil turns can be reduced, thereby reducing the size of the inductor. Attached Figure Description

[0028] Figure 1 The process of an embodiment of the present invention Figure 1 ;

[0029] Figure 2 The process of an embodiment of the present invention Figure 2 ;

[0030] Figure 3 This is a schematic diagram of the molded inductor structure in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the internal structure of the molded inductor in an embodiment of the present invention;

[0032] Figure 5 This is a bottom view of the molded inductor in an embodiment of the present invention;

[0033] Figure 6 This is a front view of the molded inductor in an embodiment of the present invention.

[0034] Table of labels in the diagram:

[0035] label name 100 Magnetic core holder 101 Central column 102 base plate 200 coil conductor 300 Magnetic core cover 400 electrode Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0037] Unless otherwise defined, the technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this disclosure pertains.

[0038] The terms "first," "second," and similar words used in this patent application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. The terms "comprising" or "including," and similar words, mean that the elements or objects preceding "comprising" or "including" encompass the elements or objects listed following "comprising" or "including," and do not exclude other elements or objects. The terms "connected" or "linked," and similar words, are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Above," "below," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] See appendix Figure 1-2 The present invention provides a method for preparing a molded inductor in its first aspect, comprising:

[0041] S100: First magnetic powder and second magnetic powder are sequentially filled into a pre-set first mold cavity and molded to obtain a magnetic core seat 100, wherein the magnetic core seat 100 includes a central column 101 and a base plate 102 connected to each other.

[0042] S200: The pre-set coil conductor 200 is sleeved on the central column 101, the two ends of the coil conductor 200 are folded to the side of the base plate 102 away from the central column 101, and the two ends of the coil conductor 200 are post-processed to form the electrode 400.

[0043] S300: Place the magnetic core seat 100 with the coil conductor 200 sleeved into the preset second mold cavity, fill the preset magnetic core cover 300 magnetic powder into the second mold cavity, and perform hot pressing to obtain the molded inductor.

[0044] The first magnetic powder, the second magnetic powder, and the magnetic core cover 300 are of different types.

[0045] Specifically, the magnetic powder of the magnetic core cover 300 includes a third magnetic powder and a fourth magnetic powder. The first magnetic powder, the second magnetic powder, the third magnetic powder and the fourth magnetic powder can be any one of carbonyl iron powder, reduced iron powder, alloy powder or amorphous powder, or a mixture of any two or more of carbonyl iron powder, reduced iron powder, alloy powder and amorphous powder. Of course, in order to further improve the density and magnetic properties of the magnetic core seat 100, it is more preferable to use any one of carbonyl iron powder, FeSiCr, FeSiAl, FeSi, FeNi magnetic powder, or a mixture of any two or more of carbonyl iron powder, FeSiCr, FeSiAl, FeSi, FeNi magnetic powder.

[0046] The post-processing includes, but is not limited to, heat treatment, grinding, roller spraying, paint stripping and electroplating.

[0047] Furthermore, the base plate 102 obtained in step S100 has symmetrical notches on both sides of one end, and the base plate 102 has a "convex" structure.

[0048] The coil conductor 200 is directly wound around the central column 101, with both ends of the coil conductor 200 passing through two notches in the base plate 102 and folded to attach to the side of the base plate 102 away from the central column 101. Alternatively, the coil conductor 200 can be wound around a pre-prepared mold to obtain a hollow coil conductor, which is then directly fitted onto the central column 101. Finally, the extended ends of the hollow coil conductor are bent and passed through the corresponding two notches to attach to the side of the base plate 102 away from the central column 101. Both methods can achieve the installation of the coil conductor 200. However, to improve efficiency, the latter method allows for the pre-winding of multiple hollow coil conductors on the mold, so that during production, only the hollow coil conductors need to be directly selected for installation.

[0049] Step S300 can also be executed in the following ways:

[0050] S301: Place the magnetic core holder 100 with the coil conductor 200 sleeved into the preset second mold cavity;

[0051] S302: Fill the two gaps on the base plate 102 with the third magnetic powder until the two gaps are filled;

[0052] S303: Then fill the second mold cavity with the fourth magnetic powder until it covers the coil conductor 200;

[0053] S304: Perform hot pressing operation on the second mold cavity to obtain a molded inductor.

[0054] Specifically, one end of the coil conductor 200 is placed in a notch on the base plate 102, and the other end of the coil conductor 200 is wound around the central post 101 and extends to another notch on the base plate 102. At this time, the magnetic core seat 100 with the coil conductor 200 is directly placed into the second mold cavity. It should be noted that the outline of the base plate 102 used for molding in the second mold cavity is roughly the same as that in the first mold cavity. The only difference is that the two notches of the base plate 102 are not closed in the second mold cavity. When filling the third magnetic powder, the third magnetic powder can directly fill the two notches. The coil conductor 200 is placed at both ends in the two notches and wrapped and sealed. Finally, the fourth magnetic powder is directly filled into the second mold cavity to completely cover the coil conductor 200. The molded inductor is obtained by performing a hot pressing operation on the second mold cavity.

[0055] Among them, the magnetic core cover 300 magnetic powder includes a third magnetic powder or a fourth magnetic powder, that is, it can be prepared by using a single magnetic powder component or by using a dual magnetic powder component;

[0056] The coil conductor 200 uses a coil with φ=0.2mm and is wound into two layers, with 4 turns in each layer. The molded inductor is a cuboid with a length of 2.0mm, a width of 1.6mm and a height of 0.8mm.

[0057] Furthermore, the base plate 102 is made of a first magnetic powder and a second magnetic powder. The first magnetic powder is disposed on the side of the base plate 102 away from the central column 101, and the central column 101 is made of a second magnetic powder.

[0058] In the process of preparing the magnetic core seat 100, the first magnetic powder and the second magnetic powder are filled into the first mold cavity in proportion and in sequence to form the magnetic core seat 100. Therefore, the base plate 102 of the obtained magnetic core seat 100 will contain a mixture of the first magnetic powder and the second magnetic powder, while the central column 101 contains only one type of second magnetic powder.

[0059] Furthermore, in order to utilize the principle of induced current generation, reduce eddy current loss and reduce the loss of the magnetic core holder 100, the permeability of the first magnetic powder is lower than that of the second magnetic powder, and the proportion of the first magnetic powder in the composition of the base plate 102 is in the range of 5-80%.

[0060] Furthermore, the fourth magnetic powder accounts for 10% to 99% of the composition of the magnetic powder in the core cover 300. The fourth magnetic powder is disposed on the side of the core cover 300 away from the coil conductor 200, and the permeability of the fourth magnetic powder is higher than that of the third magnetic powder.

[0061] Specifically, the first magnetic powder and the fourth magnetic powder are respectively disposed on the outermost upper and lower sides of the molded inductor.

[0062] Furthermore, the first magnetic powder, the second magnetic powder, the third magnetic powder, and the fourth magnetic powder are all subjected to insulation passivation treatment and have a resistivity ≥100Ω·m. More preferably, the resistivity of the first magnetic powder and the resistivity of the third magnetic powder are ≥1MΩ·m.

[0063] Furthermore, the mass ratio of the magnetic powder in the magnetic core cover 300 to the magnetic core base 100 ranges from 1 / 9 to 2 / 3.

[0064] See appendix Figure 3-6 The present invention provides a molded inductor prepared by any of the above-described preparation methods in its second aspect.

[0065] In Example 1:

[0066] First magnetic powder and second magnetic powder are sequentially filled into a pre-set first mold cavity and molded to obtain a magnetic core seat 100, wherein the magnetic core seat 100 includes a central column 101 and a base plate 102 connected to each other.

[0067] The pre-set coil conductor 200 is sleeved on the central column 101, and the two ends of the coil conductor 200 are folded to the side of the base plate 102 away from the central column 101. The two ends of the coil conductor 200 are then post-processed to form the electrode 400.

[0068] The magnetic core seat 100 with the coil conductor 200 sleeved is placed into the pre-set second mold cavity, the magnetic core cover 300 magnetic powder is filled into the second mold cavity, and hot pressing is performed to obtain the molded inductor.

[0069] Among them, the magnetic core cover 300 magnetic powder includes a fourth magnetic powder, and the first magnetic powder, the second magnetic powder and the fourth magnetic powder are of different types;

[0070] The first magnetic powder accounts for 20% of the composition of the base plate 102;

[0071] The mass ratio of the magnetic powder in the magnetic core cover 300 to the magnetic core base 100 is 3:7.

[0072] The coil conductor 200 uses a coil with φ=0.2mm and is wound into two layers, with 4 turns in each layer. The molded inductor is a cuboid with a length of 2.0mm, a width of 1.6mm and a height of 0.8mm.

[0073] In Example 2:

[0074] First magnetic powder and second magnetic powder are sequentially filled into a pre-set first mold cavity and molded to obtain a magnetic core seat 100, wherein the magnetic core seat 100 includes a central column 101 and a base plate 102 connected to each other.

[0075] The pre-set coil conductor 200 is sleeved on the central column 101, and the two ends of the coil conductor 200 are folded to the side of the base plate 102 away from the central column 101. The two ends of the coil conductor 200 are then post-processed to form the electrode 400.

[0076] The magnetic core seat 100 with the coil conductor 200 sleeved is placed into the pre-set second mold cavity, the magnetic core cover 300 magnetic powder is filled into the second mold cavity, and hot pressing is performed to obtain the molded inductor.

[0077] Among them, the magnetic core cover 300 magnetic powder includes a fourth magnetic powder, and the first magnetic powder, the second magnetic powder and the fourth magnetic powder are of different types;

[0078] The first magnetic powder accounts for 50% of the composition of the base plate 102;

[0079] The mass ratio of the magnetic powder in the magnetic core cover 300 to the magnetic core base 100 is 3:7.

[0080] The coil conductor 200 uses a coil with φ=0.2mm and is wound into two layers, with 4 turns in each layer. The molded inductor is a cuboid with a length of 2.0mm, a width of 1.6mm and a height of 0.8mm.

[0081] In Example 3:

[0082] First magnetic powder and second magnetic powder are sequentially filled into a pre-set first mold cavity and molded to obtain a magnetic core seat 100, wherein the magnetic core seat 100 includes a central column 101 and a base plate 102 connected to each other.

[0083] The pre-set coil conductor 200 is sleeved on the central column 101, and the two ends of the coil conductor 200 are folded to the side of the base plate 102 away from the central column 101. The two ends of the coil conductor 200 are then post-processed to form the electrode 400.

[0084] The magnetic core seat 100 with the coil conductor 200 sleeved is placed into the pre-set second mold cavity, the magnetic core cover 300 magnetic powder is filled into the second mold cavity, and hot pressing is performed to obtain the molded inductor.

[0085] Among them, the magnetic core cover 300 magnetic powder includes a fourth magnetic powder, and the first magnetic powder, the second magnetic powder and the fourth magnetic powder are of different types;

[0086] The first magnetic powder accounts for 70% of the composition of the base plate 102;

[0087] The mass ratio of the magnetic powder in the magnetic core cover 300 to the magnetic core base 100 is 3:7.

[0088] The coil conductor 200 uses a coil with φ=0.2mm and is wound into two layers, with 4 turns in each layer. The molded inductor is a cuboid with a length of 2.0mm, a width of 1.6mm and a height of 0.8mm.

[0089] In Example 4:

[0090] First magnetic powder and second magnetic powder are sequentially filled into a pre-set first mold cavity and molded to obtain a magnetic core seat 100, wherein the magnetic core seat 100 includes a central column 101 and a base plate 102 connected to each other.

[0091] The pre-set coil conductor 200 is sleeved on the central column 101, and the two ends of the coil conductor 200 are folded to the side of the base plate 102 away from the central column 101. The two ends of the coil conductor 200 are then post-processed to form the electrode 400.

[0092] The magnetic core seat 100 with the coil conductor 200 sleeved is placed into the pre-set second mold cavity, the magnetic core cover 300 magnetic powder is filled into the second mold cavity, and hot pressing is performed to obtain the molded inductor.

[0093] Among them, the magnetic core cover 300 magnetic powder includes a third magnetic powder and a fourth magnetic powder, and the first magnetic powder, the second magnetic powder, the third magnetic powder and the fourth magnetic powder are of different types;

[0094] The first magnetic powder accounts for 20% of the composition of the base plate 102;

[0095] The mass ratio of the magnetic powder in the magnetic core cover 300 to the magnetic core base 100 is 3:7.

[0096] The fourth magnetic powder accounts for 10% of the composition of the magnetic powder in the magnetic core cover 300.

[0097] The coil conductor 200 uses a coil with φ=0.2mm and is wound into two layers, with 4 turns in each layer. The molded inductor is a cuboid with a length of 2.0mm, a width of 1.6mm and a height of 0.8mm.

[0098] In the comparative example:

[0099] First magnetic powder is filled into a pre-set first mold cavity and molded to obtain a magnetic core seat 100, wherein the magnetic core seat 100 includes a central column 101 and a base plate 102 connected to each other.

[0100] The pre-set coil conductor 200 is sleeved on the central column 101, and the two ends of the coil conductor 200 are folded to the side of the base plate 102 away from the central column 101. The two ends of the coil conductor 200 are then post-processed to form the electrode 400.

[0101] The magnetic core seat 100 with the coil conductor 200 sleeved is placed into the pre-set second mold cavity, the magnetic core cover 300 magnetic powder is filled into the second mold cavity, and hot pressing is performed to obtain the molded inductor.

[0102] Among them, the magnetic core cover 300 magnetic powder includes a fourth magnetic powder, and the first magnetic powder, the second magnetic powder and the fourth magnetic powder are of different types;

[0103] The mass ratio of the magnetic powder in the magnetic core cover 300 to the magnetic core base 100 is 3:7.

[0104] The coil conductor 200 uses a coil with φ=0.2mm and is wound into two layers, with 4 turns in each layer. The molded inductor is a cuboid with a length of 2.0mm, a width of 1.6mm and a height of 0.8mm.

[0105] The molded inductors of Examples 1-4 and the comparative example were tested at 1MHz, and the inductor test performance comparison table is as follows:

[0106] Inductance Test Performance Comparison Table

[0107] Inductance value / (1MHz, uH) Rs / (mΩ) Example 1 0.96 188 Example 2 1.01 171 Example 3 1.08 142 Example 4 1.12 120 Comparative Example 0.85 196

[0108] As can be directly seen from the inductance performance comparison table above, compared to the comparative examples, Examples 1-4 can simultaneously guarantee higher inductance values ​​and higher current withstand voltage characteristics. Therefore, the inductors manufactured using the embodiments of the present invention can simultaneously achieve higher permeability and maintain or reduce losses.

[0109] The above description is merely an embodiment of the present invention. It should be noted that those skilled in the art can make improvements without departing from the inventive concept, but these improvements all fall within the protection scope of the present invention.

Claims

1. A method for preparing a molded inductor, characterized in that, Comprising: S100: Sequentially fill a first magnetic powder and a second magnetic powder into a pre-set first mold cavity and perform molding to obtain a magnetic core base, wherein the magnetic core base includes a central column and a bottom plate connected to each other; S200: Sleeve a pre-set coil conductor on the central column, turn the two ends of the coil conductor to the side of the bottom plate away from the central column, and perform post-treatment on the two ends of the coil conductor to form electrodes; S300: Place the magnetic core base sleeved with the coil conductor into a pre-set second mold cavity, fill a pre-set magnetic core cover magnetic powder into the second mold cavity, and perform hot pressing to obtain a molded inductor; Wherein, the types of the first magnetic powder, the second magnetic powder, and the magnetic core cover magnetic powder are different; Both sides at one end of the bottom plate are provided with symmetrical gaps, the bottom plate has a structure similar to a "convex" character, and the magnetic core cover magnetic powder includes a third magnetic powder and a fourth magnetic powder; The S300 includes: S ​ ​ ​ ​ 2. The method for preparing the molded inductor according to claim 1, characterized in that, ​ 3. The method for preparing a molded inductor according to claim 1, characterized in that, ​ 4. The method for preparing a molded inductor according to claim 1, characterized in that, ​ 5. The method for preparing a molded inductor according to claim 1, characterized in that, ​ ​

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