Method for manufacturing a composite power inductor

Abstract

A plurality of pre-molded cylindrical upper core blanks are respectively and vertically inserted into insertion holes of an inductor core insertion support plate, and the support plate is provided with a plurality of insertion holes in a penetrating manner; and then coils are wound on the outer circumferential surfaces of the core blanks through an automatic winding device, so that the core blanks are used as the inductor cores. Thus, both peeling damage of the coating on the winding coil and unwinding of the winding coil in the inductor being manufactured are prevented, which enables stable maintenance and thus enables manufacturing of a composite power inductor that is uniform in quality such as inductance value.

Description

Technical Field

[0001] This invention relates to a novel manufacturing method for mass-producing composite power inductors in a single operation. Background Technology

[0002] As is well known in the art, power inductors are commonly used in power supply devices and circuits, such as power circuits that convert a specific voltage to a desired voltage (e.g., integrated circuits, ICs), and are designed to exhibit low resistance characteristics while maintaining constant inductance. Depending on the manufacturing method, these power inductors are generally classified into three types: wire-wound, thin-film, and multilayer. Furthermore, the power inductor body (called the core) can be selected from magnetic metal powders, such as Fe-Si-Cr powder, Ni-Zn-based ferrite, Mn-Zn-based ferrite, Fe-based alloy powder, carbonyl iron powder, or combinations thereof, so that the power inductor body is adapted to the electrical characteristics according to the intended use.

[0003] In particular, the present invention relates to an improved method for manufacturing a "winding type" composite power inductor (hereinafter referred to as a "power inductor" or more simply an "inductor").

[0004] Prior to the present invention, for example, as disclosed in Korean Patent No. 10-790777 (Patent Document 1), a method for manufacturing a power inductor had been used, in which an air core coil wound with a predetermined number of turns was placed in a predetermined position inside a pressure molding machine, a certain amount of selected magnetic metal powder was injected and filled into the pressure molding machine, and compression molding was performed under a pressure designed in the pressure molding machine.

[0005] Furthermore, Korean Patent No. 10-1430427 (Patent Document 2) discloses a method for obtaining a secondary molded body, i.e., a final power inductor, by means of: transferring an air-core coil to a primary molding machine while holding the air-core coil on a winding plate, the air-core coil being obtained by continuously winding the coil around the outer peripheral surface of each of a plurality of winding pins integrally protruding from the surface of a metal coil winding plate; injecting magnetic metal powder into the primary molding machine and performing compression molding to obtain a preliminary molded body; placing the air-core coil obtained by removing the coil winding plate from the preliminary molded body into a final molding machine; and injecting the same magnetic metal powder from the top of the final molding machine and performing compression molding to obtain a secondary molded body (i.e., the final power inductor).

[0006] In addition, Korean Patent No. 10-2178709 (Patent Document 3) discloses a method for manufacturing a power inductor, wherein a groove is provided for accommodating an air-core coil, the air-core coil being accommodated in each air-core coil receiving groove of a predetermined molded body obtained by pressure molding with magnetic metal powder, and the same magnetic metal powder is filled into the air core of the air-core coil for secondary pressure molding.

[0007] These prior patent documents share the common feature of placing individually wound hollow coils inside a pressure molding machine and injecting and filling a predetermined magnetic metal powder into the pressure molding machine for pressure molding under a designed pressure.

[0008] Furthermore, in Korean Patent Nos. 10-1044607 (Patent Document 4) and 10-1044608 (Patent Document 5), a preliminary core is prepared by compression molding magnetic metal powder in a preliminary core molding machine. The outer diameter of the preliminary core is designed to generally correspond to the inner diameter of the air-core coil, making it equal to or slightly higher than the height of the air-core coil. Subsequently, the preliminary core is inserted into the hollow core of the air-core coil, aligned in a separate pressure molding machine. Magnetic metal powder is then filled into the molding machine, and the magnetic metal powder is compression molded under a predetermined molding pressure to obtain the desired magnetic core. Next, external electrical terminals are deposited on the left and right leads exposed to the outside of the magnetic core at predetermined locations to complete the power inductor product.

[0009] Korean Patent No. 10-1275168 (Patent Document 6) discloses an example of a method for depositing external terminals of an inductor.

[0010] However, in the methods disclosed in the aforementioned prior patent documents, imbalances can easily occur due to the molding pressure transmitted to the periphery of the coil during the compression molding process, resulting in variations in the filling density of the magnetic metal powder. This leads to fine cracks (crazing) appearing in the magnetic core around the coil of the finished inductor, thus causing a significant decrease in product quality.

[0011] Furthermore, inside the inductor manufactured by the methods described in each of the previous patent documents 1 to 5, when magnetic metal powder is injected into the inner and outer circumferences of the air-core coil and compression molded in a molding machine, a portion of the air-core coil is crushed, resulting in changes in the coil winding height or partial unwinding within the coil winding. This often leads to an unstable winding state of the air-core coil embedded in the magnetic metal. Additionally, when the preliminary core is inserted into the air-core coil, damage such as peeling of the coil's insulating coating may occur due to the friction generated during insertion. Therefore, in electrical / electronic circuits using such power inductors, short circuits may occur due to electrical short circuits, potentially causing damage to the circuit itself.

[0012] In these traditional inductor products, the increased distribution of electrical characteristics such as inductance (and / or resistance) significantly reduces the quality and yield of finished inductors. Furthermore, in inductors where coil unwinding occurs, for example, the inductance value increases, which is undesirable as the inductor is classified as a defective product. In particular, in the case of composite power inductors used in components and accessories of various precision machines or devices, such as today's medical devices, aircraft, automobiles, rocket weapons, autonomous vehicles, and drones, such instability or non-uniformity in inductance, resistance, etc., may lead to the inoperability or malfunction of the aforementioned precision machines. Therefore, it is necessary to identify and improve the causes of quality defects during the manufacturing process of composite power inductors. Summary of the Invention

[0013] [Technical Issues]

[0014] One object of the present invention is to provide an improved method for manufacturing high-quality inductors in which, during the molding of power inductors, the initial winding state is maintained almost exactly as is without causing unwinding in the air-core coil, and all relevant electrical characteristics, such as inductance value, are uniform throughout the manufactured product.

[0015] [Technical Solutions]

[0016] Therefore, as a result of in-depth research, the applicant has completed this invention to solve the problems of the aforementioned conventional technology. That is, the problems and objectives of this invention are achieved through the following means.

[0017] A method for manufacturing a composite power inductor, the method comprising: - a first step: molding an upper core blank and a lower core blank formed from magnetic metal powder;

[0018] - Step 2: Provide an upper core blank insertion support plate, the upper core blank insertion support plate having an appropriate number of insertion holes formed horizontally and vertically, so that the lower edge of the upper core blank is inserted into the insertion holes and simultaneously accommodated in the upper core blank insertion support plate;

[0019] - Step 3: Insert the lower edge of the upper core blank vertically into the insertion hole of the upper core blank insertion support plate, and transfer the lower edge of the upper core blank to the automatic coil winding machine to wind a coil on the outer circumferential surface of each upper core blank;

[0020] - Step 4: The upper core blank with the coil is inserted into the support plate by transferring the upper core blank into the support plate and placing it into the molding machine. Magnetic metal powder is filled into the molding machine and compression molding is performed to obtain the first preliminary molded body.

[0021] Step 5: By pushing the lower core blank into the lower end of the upper core of the first preliminary molded body and performing compression molding, a second preliminary molded body is obtained; and

[0022] - Step 6: Obtain the third preliminary molded body by subjecting the second preliminary molded body to a conventional underwater isotropic compression molding process.

[0023] In the method of (1), before the third step begins, a tape selected from silicone tape, synthetic resin film tape and paper tape can be pasted onto the back of the upper core blank inserted into the support plate as an auxiliary support unit for supporting the support plate.

[0024] In the method of (1), the order of the first step and the second step can be interchanged.

[0025] In the method of (1), the upper core blank insert support plate can be formed of metal or synthetic resin sheet.

[0026] In the method of (1), the inner diameter of each core insertion hole of the upper core blank inserted into the support plate can correspond to the outer diameter of the upper core blank.

[0027] In method (1), the thickness of the upper core blank inserted into the support plate can be 0.5 mm to 1 mm.

[0028] In the method of (1), the fourth step can be performed after the upper core blank is removed and the support plate is inserted.

[0029] [Beneficial Effects]

[0030] According to the present invention, damage to the air coil coating and unwinding of the air coil that may occur during the molding of the inductor can be actively prevented, thereby obtaining a high-quality inductor product with key electrical properties such as uniform inductance value. Attached Figure Description

[0031] Figure 1 (A) is a direct representation of what is described in Patent Document 4. Figure 5 A partial diagram, and Figure 1 (B) is a three-dimensional view (photograph) showing the interior of a conventional inductor product, where coil unwinding occurs.

[0032] Figure 2 (A) to 2(C) are views depicting examples of the design of an inductor core according to the present invention, wherein the upper core blank and the lower core blank used in the present invention can be designed by the method respectively.

[0033] Figure 3 (A) is a plan view depicting the insertion of the upper core blank into a support plate, which has multiple insertion holes formed transversely and longitudinally to facilitate the insertion of the core blank through... Figure 2 The upper core blank prepared by the method is vertically inserted into the insertion hole, and Figure 3 (B) is along Figure 3 (A) is a sectional view taken by line aa.

[0034] Figure 4 (A) describes the insertion of the upper core blank into... Figure 3 (A) is a perspective view of the state of the upper core blank inserted into each insertion hole of the support plate, and Figure 4 (B) is along Figure 4 (A) is a sectional view taken by line bb.

[0035] Figure 5 (A) is a perspective view depicting the state of the coil wound around the outer peripheral surface of each upper core blank, and Figure 5 (B) is along Figure 5 (A) is a sectional view taken by line cc.

[0036] Figure 6a (A) is a cross-sectional view depicting the process of placing an upper core blank, into which an upper core blank is inserted, into a support plate in a molding machine, and filling the molding machine with a predetermined amount of magnetic powder for compression molding to obtain a first preliminary molded block, wherein the upper core blank has a coil wound around its outer circumferential surface. Figure 6a (B) shows from Figure 6a A cross-sectional view of the first preliminary molding block obtained in step (A) with the upper core blank removed and inserted into the support plate. Figure 6a (C) is shown Figure 6a (B) A plan view of the surface state, and Figure 6a (D) is shown Figure 6a (B) is a plan view of the bottom surface.

[0037] Figure 6b(A) describes the process by Figure 6a (B) A view of the process of forming the second preliminary molded body from the first preliminary molded body, and Figure 6b (B) is a cross-sectional view of the obtained second preliminary molded body, in which the enlarged portion shows the shape of the lead wire L exposed on the bottom surface.

[0038] Figure 7 This is a flowchart view of a series of main process steps performed in this invention.

[0039] Figure 8 (A) is a view showing the assembly state of the second preliminary molded body / transfer jig / backplate according to the present invention. Figure 8 (B) is a description of... Figure 8 (A) A cross-sectional view of the obtained second preliminary molded body, and Figure 8 (C) is a view depicting the state of the bottom surface of the molded object.

[0040] Figure 9 (A) and Figure 9 (B) is a schematic diagram showing the state before and after the external terminals T and T are deposited on the leads L and L of each inductor.

[0041] Figure 10 It is a cross-sectional image comparing the state of the coils in the product sample of the present invention and the control product sample.

[0042] Figure 11 (A) and Figure 11 (B) is a graph used to compare and explain the electrical properties of the sample of the present invention and the control sample. Detailed Implementation

[0043] As mentioned above, Figure 1 (A) shows Patent Document 4, which is the aforementioned prior art patent document. Figure 5 The prior art described herein is an example, and a method is briefly illustrated for molding a final inductor product by inserting a preliminary core molded body B, which is molded using magnetic metal powder, into the hollow portion (i.e., the hollow core) of the coil element 15, such that the preliminary core molded body B is assembled with separate upper and preliminary peripheral molded bodies (the reference numerals of which are omitted) and pressed into shape. Figure 1 (B) is a perspective image obtained by cone-beam computed tomography (CBCT; model name XSCAN-H130-OCT, applied voltage 130kV, XAVIS Co., Ltd., Seongnam City, Korea) of the interior of a conventional inductor product that has experienced coil unwinding.

[0044] However, as Figure 1As shown in image (B), inductors produced using conventional methods suffer from a high defect rate due to frequent unwinding in the wound air-core coil. This unwinding is believed to be caused by the fact that even when the specifications of the initial core molded body B (particularly the diameter) are designed considering the specifications of the coil element 15, the coating of the air-core coil can peel and be damaged due to friction caused by contact with the coil during insertion into the air core. This results in a short circuit at the damaged portion when the power supply or the winding state of the coil changes due to the extrusion pressure during compression molding. This extrusion pressure is caused by the gap created by the space between the core molded body B and the coil.

[0045] Therefore, as described above, the present invention is accomplished by demonstrating a method that minimizes damage to the coating of the air-core coil and the unwinding of the coil.

[0046] In other words, the method of the present invention is significantly different from the method of Patent Document 4. In particular, during the inductor molding process, instead of using an air-core coil formed by winding the coil around the winding pin of a winding machine, a coil is directly and firmly wound onto the pre-formed core blank. This significantly reduces the occurrence of defects in the inductor product during the molding process, such as damage to the coil coating and coil unwinding.

[0047] As described above, the present invention aims to improve conventional methods. The method of the present invention will be described in detail below with reference to the accompanying drawings, step by step.

[0048] Step 1: Molding the upper and lower core blanks;

[0049] In order to implement the present invention, such as Figure 2 As shown in (A), a predetermined amount of magnetic metal powder 10 is injected and filled into a pressure molding machine M1, and then extruded using a pressure head PR1 to mold the material. Figure 2 (B) The initial upper core blank 11 (hereinafter referred to as "upper core blank 11"), wherein the pressure head PR1 is provided with a pressure pin P.

[0050] According to the present invention, Fe-Si-Cr powder with an average particle size of about 10 μm is used as magnetic metal powder.

[0051] In one embodiment of the present invention, 0.12 g of Fe-Si-Cr powder is injected and filled into... Figure 2 (A) shows a single core blank molding machine M1 (standard mold size 40mm × 40mm × 60mm), and the pressure head PR1 is set to a molding pressure (e.g., approximately 5 tons / cm). 2The upper core blank 11 is obtained by molding under the following conditions. The upper core blank 11 has a cylindrical shape with a diameter R1 of 3 mm and a height H1 of 3 mm. In a similar manner, a thin cylindrical (or disc-shaped) preliminary lower core blank 12 (R2 = 3 mm and H2 = 1.5 mm; hereinafter referred to as "lower core blank 12") is molded under the same molding conditions. Figure 2 (C) shows the molding process performed separately. Refer to... Figure 2 (A) If necessary, the lower pressure head PR1' can be mounted on the molding machine M1 so that the molded body (upper core blank 11 and lower core blank 12) can be easily removed from the lower part of the molding machine M1 by opening the lower pressure head PR1' after the molding operation. However, for simplicity, the lower pressure head PR1' will be omitted below.

[0052] In carrying out this invention, the magnetic metal powder used for molding the upper core blank 11 and the lower core blank 12 is a material obtained by mixing Fe-Si-Cr powder with a thermosetting resin-based (e.g., epoxy-based) binder in an appropriate proportion (based on an amount of about 1 wt% to 5 wt% of the magnetic metal powder). Various corresponding magnetic metal powder materials are commercially available. In this case, the magnetic metal powder used for molding the lower core blank 12 can be the same composition as the Fe-Si-Cr powder described above, or it can be a combination of different compositions or two or more magnetic metal powders.

[0053] In this case, the use of Figure 2 (A) shows an example of a single molding machine M1 molding the upper core blank 11 and the lower core blank 12. However, when using a molding equipment consisting of multiple single core blank molding machines M1 arranged in parallel, multiple upper core blanks and lower core blanks can be molded separately in a large quantity at once. In this case, the pressure head PR1 can be equipped with multiple pressure pins P, the number of which corresponds to the number of molding machines M1.

[0054] Step 2: Preparation of inserting the core blank into the support plate

[0055] like Figure 3As shown in (A), an upper core blank insertion support plate 20 is prepared for inserting and holding the upper core blank 11. For this purpose, according to an embodiment of the invention, the support plate 20 is prepared from a stainless steel sheet material with a width of 45 mm, a length of 45 mm, and a thickness of 1 mm. The thickness of the support plate 20 is preferably 0.5 mm to 1 mm or less, for example, 0.5 mm, intended to ensure that the coil is wound as close as possible to the lower edge of the upper core during the coil winding process described below. Generally, the smaller the thickness of the support plate 20, the lower the height of the upper core blank 11 can be selected. Next, a plurality of circular insertion holes 21 are formed through the support plate in both the transverse and longitudinal directions, for example, 6 columns and 6 rows (6×6=36) of circular insertion holes 21 with a diameter of approximately 3 mm. The front-to-back and left-to-right spacing between each upper core blank insertion hole 21 and its adjacent insertion hole is set to 2.0 mm. The state of having a plurality of upper core blank insertion holes 21 is as follows: Figure 3 (A) and Figure 3 (B) provides a good description of this. Figure 3 (A) is a top view of the core blank inserted into the support plate 20. Figure 3 (B) is along Figure 3 (A) is a cross-sectional view taken by line aa.

[0056] In implementing this invention, a support plate 20 made of stainless steel sheet is used, but the invention is not limited to this material. Any material can be used, as long as it can be processed very thin, is not easily deformed at operating temperatures, and has an insertion hole 21 through which the upper core blank 11 can be fully inserted and supported. For example, a rigid synthetic resin plate can be used. The inner diameter of the upper core blank insertion hole 21 is designed to correspond to the outer diameter of the upper core blank 11 to be inserted, and in this case, the size of the coil to be wound on the outer circumferential surface of the upper core blank 11 is also taken into consideration.

[0057] The molding step of the upper core blank 11 and the preparation step of inserting the upper core blank into the support plate 20 are not performed in a fixed order, and can be performed in different orders when necessary, which does not affect the result.

[0058] Step 3: Insertion of the upper core blank and coil winding

[0059] The lower edge of each upper core blank 11 is inserted into each insertion hole 21 formed in the support plate 20 and held vertically. In this case, the upper core blank 11 is inserted such that the outer circumferential surface of the lower edge fits tightly with the inner circumferential surface of the insertion hole 21. See [reference needed] for the state of the upper core blank 11 inserted into the support plate 20. Figure 4 (A) and as Figure 4 (A) sectional view Figure 4(B) This will make it clear. Preferably, immediately before and after the upper core blank 11 is inserted, any auxiliary support unit 30 selected from synthetic resin film tape, silicone tape, and paper tape is attached to the bottom (back) surface of the support plate 20, thereby facilitating the prevention of the upper core blank 11 from falling off, tilting, and / or shaking during operation of the support plate 20, such as during the transfer of the support plate 20 to a subsequent coil winding machine. However, this auxiliary support unit 30 is not essential.

[0060] Subsequently, the support plate 20, with each upper core blank 11 inserted and supported in the insertion hole 21, is transferred to an automatic coil winding machine (not shown), which is operated such that the coil 31 is securely wound multiple turns (e.g., 5 to 10 turns) on the outer circumferential surface of each upper core blank 11. The coil 31 is supplied directly from a coil feeder (not shown) provided in the automatic coil winding machine.

[0061] therefore, Figure 5 (A) depicts the final state of the coil 31 continuously wound around the outer circumferential surface of each upper core blank 11. Furthermore, Figure 5 (B) is a cross-sectional view taken along line cc, depicting the final state of coil 31 wound on each upper core blank 11. In this case, coil 31 is a commercially available general-purpose enameled copper wire with a diameter of 0.2 mm (200 μm).

[0062] Step 4: Molding of the first preliminary shaped body after coil winding

[0063] like Figure 6a As shown in (A), the upper core blank 11, to which the coil 31 has been inserted and held, is placed in the molding machine M2 via the upper core blank insertion support plate 20 (with an auxiliary support plate 30 attached to its back). A predetermined amount (approximately 35g) of selected magnetic metal (Fe-Si-Cr) powder 10 is injected into the molding machine M2, and a pressure of 1 ton / cm is applied through the pressure head PR2. 2 The pressure, to mold like Figure 6a (B) shows the first preliminary molded body 42. Subsequently, the support plate 20 to which the auxiliary support unit 30 is attached is removed from the bottom surface of the first preliminary molded body 42. In this case, the surface and bottom surfaces of the first preliminary molded body 42 are as follows: Figure 6a (C) and Figure 6a As shown in (D).

[0064] Step 5: Adjusting the position of the winding coil

[0065] As described above, since the upper core blank 11 is inserted into the surface of the support plate 20, the coil 31 wound on it is close to the bottom surface of the first preliminary molded body 42. However, in order to ensure the required electrical performance of the inductor, the coil 31 must be arranged in the central part of the interior of the first preliminary molded body 42.

[0066] to this end, Figure 6a (B) The first preliminary molded body 42 is placed in an inverted state (i.e., the surface and bottom surfaces are flipped upside down) inside the molding machine M3 (PR2 is equipped with a pressure pin P), as shown. Figure 6b As shown in (A). Subsequently, the lower core blank 12 (approximately 3 mm in diameter and approximately 1.5 mm in height) is placed between the lower edge of the upper core blank 11 and the leads L and L on both sides thereon. Magnetic metal (Fe-Si-Cr) powder 10 (approximately 0.05 g per upper core blank 11) is added to it, and then the pressure head PR2 is pressed at 1 ton / cm. 2 Or higher pressure can be applied to push the lower core blank 12 using the pressure pin P. As a result, the upper core blank 11, with the coil 31 already wound, is pulled from... Figure 6a (B) The initial position is pushed slightly towards the center and positioned. The reason for placing the coil in the center of the inductor is to achieve inductance characteristics with minimal magnetic loss. The resulting molded body is the second preliminary molded body 43. Therefore, the two leads L and L inside the second preliminary molded body 43 are also slightly spaced upward from the inner bottom surface of the preliminary molded body 43 toward the center. That is, in this step, each coil lead L is located at the lower part of the second preliminary molded body 43, as shown in Figure 43. Figure 6b As shown in the enlarged portion of (B).

[0067] because Figure 6a The processes of (A) and 6a(B) are partially similar to those in the aforementioned Patent Document 3. Figure 2 The relevant descriptions (paragraphs

[0031] to

[0036] ) are included as part of this specification and are provided for reference. In this case, as mentioned above, depending on the required performance of the final inductor product, the Fe-Si-Cr powder 10 may be replaced by a composition that is the same as or different from that of the upper core blank 11 or the lower core blank 12.

[0068] It can be seen that the fifth step of the method of the present invention is performed when the core blank insert support plate 20 has been removed.

[0069] Figure 7 For ease of understanding, a flowchart of the process from the first to the fifth steps of the method of the present invention described above is provided.

[0070] Step 6: Underwater isotropic molding and separation of individual inductor products (conventional process)

[0071] The second preliminary molded body 43 obtained in step 5 is transferred to, as Figure 8 (A) shows the interior of a metal transfer fixture 44 with predetermined standards, and a back plate 45 in close contact with its bottom surface, such that the second preliminary molded body 43, the metal transfer fixture 44, and the back plate 45 are integrally assembled. The assembly FA, ​​including the second preliminary molded body 43 / transfer fixture 44 / back plate 45, undergoes a known underwater isotropic compression molding process. For this purpose, the assembly FA is placed in a commercially available vacuum-sealed bag (not shown) and molded using an isotropic pressure molding machine (not shown) at 5 ton / cm². 2 Molding was performed under molding pressure at 80°C for 0.5 hours (see paragraphs

[0033] to

[0035] of Patent Document 3). As a result, the following was obtained: Figure 8 (B) shows the third preliminary molded body 46.

[0072] In this case, since the upper core blank 11 and the lower core blank 12 have been integrated with the Fe-Si-Cr powder 10 during the molding process, it is observed that the mutual boundaries between the magnetic metal powder (i.e., Fe-Si-Cr powder 10), the upper core blank 11 and the lower core blank 12 in the third preliminary molded body 46 disappear.

[0073] Subsequently, the bottom surface of the third preliminary molded body 46 is polished using appropriate polishing equipment. Therefore, as the bottom surface of the third preliminary molded body 46 is polished, the enameled insulation layer is also removed, and as... Figure 8 As shown in the enlarged portion of (B), a pair of left and right coil leads L and L' are clearly exposed on the bottom surface of the third preliminary molded body, and thus appear as... Figure 8 The pattern shown in (C) is fully presented on the bottom surface.

[0074] Subsequently, after cleaning the polished surface, a sputtering process known in the art is applied to deposit a set of left and right external electrical terminals T and T corresponding to the exposed surfaces of a set of leads L and L. In carrying out the present invention, silver (Ag) is used as the sputtering target metal, but the present invention is not limited thereto, and gold (Au), copper (Cu), nickel (Ni), etc., can also be used to deposit electrode terminal films. Since the terminal deposition process by the above sputtering method is known, and in the entire specification of Patent Document 6 which is part of this specification (paragraphs

[0023] to

[0032] and Figures 6(A), (B) and Figure 7The description is relatively detailed in [ ], so further description will be omitted. Next, multiple (6×6=36) individual inductors I are cut and separated from the third preliminary molded body 46. The set dimensions of the individual inductors I after cutting and separation are 5mm wide, 5mm long, and 2mm high. Since an example of the method for cutting and separating the individual inductors I has been described in detail in Patent Document 5 (see paragraph

[0042] and Figure 6(D)), it will not be repeated here.

[0075] Figure 9 (A) and Figure 9 (B) The models are depicted before and after the electrical terminals T and T are deposited on the front ends of the coil leads L and L, respectively.

[0076] Step 7: Quality Inspection and Comparative Testing

[0077] The samples of the inductor products obtained in Step 6 and pursued by this invention (“Invention Samples”) were subjected to quality inspection. For the comparative test used for quality inspection, a commercially available composite power inductor product manufactured by conventional methods (model name 50204R7C, SSTIC., Anyang City, Korea) was used as a control product (“Control Sample”). Both the Invention Samples and the Control Samples were randomly selected. All samples had the same dimensions, 5mm × 5mm × 2mm; the magnetic metal components of the main body (core) were typically 8 turns of Fe-Si-Cr (including 3% thermosetting resin binder) and copper coils (200μm in diameter).

[0078] (1) Comparison of the shapes of the internal winding coils

[0079] To confirm the longitudinal cross-sectional shape of each coil in randomly selected samples A and B of the present invention and control samples a and b, an EcoMetal sample processor was used. TM Cross-sectional processing was performed on samples 30 (Buehler). After cross-sectional processing, the cross-sectional shape of each sample was observed using an optical microscope (BX53MRF, Olympus / Mosaic V2.2 image acquisition software). In this case, the measurement magnification was set to ×50. The results are as follows. Figure 10 As shown. Therefore, it was observed that the internal winding coils of control samples a and b deviated from the initial winding state and were both pushed outward on average. However, the internal winding coils of the present invention samples A and B exhibited a very stable shape, which on average maintained the initial winding state.

[0080] (2) Comparison of inductance values

[0081] Similarly, the inductance values ​​of randomly selected control samples a and b, as well as the inductance values ​​of samples A and B of the present invention, were measured and compared. For the measurements, 20 groups of samples were used, each consisting of control sample a+b and sample A+B of the present invention. Therefore, the inductance values ​​for samples 1 to 20 in the table are half the sum of the inductance values ​​of control samples a and b, and the same applies to the samples of the present invention. Inductance was measured using an LCR meter (model: IM3536 LCR meter, HIOKI). In this case, a HIOKI L2001 probe was used as the test fixture, and the measurement conditions were a frequency of 100 kHz and a voltage of 1 V. The results are shown in Table 1 below.

[0082] [Table 1]

[0083] Inductance values ​​(μH) of the control sample and the sample of the present invention

[0084]

[0085]

[0086]

[0087] In Table 1, when comparing the standard deviations of the inductance values ​​obtained from experiments on the control sample and the sample of the present invention, the standard deviation of the inductance value of the control sample was 0.20, while the standard deviation of the inductance value of the sample of the present invention was 0.10. From a statistical perspective, the larger the standard deviation, the greater the deviation of the measured value from the mean, which means that the distribution range of the measured value is wider. Conversely, the smaller the standard deviation (i.e., the closer it is to 0), the closer the measured value is to the mean, which means that the distribution range of the measured value is narrower.

[0088] For a more detailed comparison, Figure 11 (A) and Figure 11 The results in Table 1 are shown in the distribution plot of (B).

[0089] As shown in Table 1, Figure 11 The inductance values ​​of the control sample in (A) are distributed over a very wide range, from 3.90 μH to approximately 4.75 μH (i.e., far from the average level). On the other hand, it can be seen that... Figure 11 The inductance values ​​of the present invention samples in (B) are concentrated and narrowly distributed in a very narrow range of about 4.5 μH to 5.0 μH (i.e., close to the average value).

[0090] These results clearly demonstrate that, compared to the control samples, the samples of the present invention exhibit remarkably stable and high-quality average inductance values. Specifically, according to the present invention, by maintaining the initial winding state virtually unchanged during the molding of the composite power inductor without inducing coating peeling and / or unwinding in the inner coil of the inductor, high-quality products with uniform electrical characteristics (such as inductance values) can be provided throughout the manufactured composite power inductor product. Therefore, it can be said that the method of the present invention has significant implications for the manufacturing of components and accessories for various precision machines or equipment, such as medical devices, aircraft, automobiles, rocket weapons, autonomous vehicles, and drones.

[0091] In the foregoing, although the present invention has been described with respect to the best embodiments of the conventional techniques for improving methods of manufacturing power inductors, those skilled in the art will recognize that modifications, alterations, additions / removals of components of the present invention are within the scope of the present invention.

[0092] [Explanation of reference numerals in the attached figures]

[0093] 10: Magnetic metal powder

[0094] 11: Upper core blank

[0095] 12: Lower core blank

[0096] 20: Insert the upper core blank into the support plate

[0097] 21: Insertion hole for upper core blank

[0098] 30: Auxiliary support unit

[0099] 31: Coil

[0100] 42: First preliminary molded body

[0101] 43: Second preliminary molded body

[0102] 44: Jig

[0103] 45: Back panel

[0104] 46: Third preliminary molded body

[0105] M1, M2, M3: Molding machines

[0106] PR1, PR2: Indenter

[0107] P: Pressure pin

[0108] I: Inductor

[0109] L: Lead wire

[0110] T: External electrical terminal

Claims

1. A method for manufacturing a composite power inductor, the method comprising: -Step 1: Molding the upper and lower core blanks formed from magnetic metal powder; - Step 2: Provide an upper core blank insertion support plate, wherein the upper core blank insertion support plate is formed with an appropriate number of insertion holes in the transverse and longitudinal directions, so that the lower edge of the upper core blank is inserted into the insertion holes and simultaneously accommodated in the upper core blank insertion support plate; - Step 3: Vertically insert the lower edge of the upper core blank into the insertion hole of the upper core blank insertion support plate, and transfer the upper core blank insertion support plate to the automatic coil winding machine to wind a coil on the outer circumferential surface of each upper core blank. - Step 4: By inserting the upper core blank with the coil wound around it into the support plate and placing it in the molding machine, filling the molding machine with the magnetic metal powder, and performing compression molding, a first preliminary molded body is obtained; Step 5: By pushing the lower core blank into the lower end of the upper core of the first preliminary molded body and performing compression molding, a second preliminary molded body is obtained; and - Step 6: Obtain the third preliminary molded body by subjecting the second preliminary molded body to a conventional underwater isotropic compression molding process.

2. The method according to claim 1, wherein, Before the third step begins, a tape selected from silicone tape, synthetic resin film tape, and paper tape is attached to the back of the upper core blank insertion support plate as an auxiliary support unit to assist the support force of the support plate.

3. The method according to claim 1, wherein, The order of the first step and the second step is interchangeable.

4. The method according to claim 1 or 3, wherein, The upper core blank is inserted into the support plate, which is formed of a metal or synthetic resin sheet.

5. The method according to claim 1, wherein, The inner diameter of each core insertion hole in the upper core blank inserted into the support plate corresponds to the outer diameter of the upper core blank.

6. The method according to claim 1, wherein, The thickness of the upper core blank inserted into the support plate is 0.5 mm to 1 mm.

7. The method according to claim 1, wherein, The fourth step is performed after the upper core blank is removed from the insertion support plate.

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