Low loss inductor

Abstract

To provide a method of manufacturing an inductor with reduced loss by an electrochemical additive manufacturing (ECAM) process.SOLUTION: The inductor includes a first terminal, a second terminal, and a conductor structure between the first terminal and the second terminal. The ECAM process grows the copper structure only in the active areas 22 between the anode segments 21 in a matrix-like pattern with rows and columns and the bottom of the cathode 20, establishing the monolithic structure of the inductor. Porosity and resistive losses are reduced, allowing for improved reliability and energy efficiency.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to the field of inductors, and more particularly to low-loss inductors that can be utilized in DC-DC converters. Additionally, the present invention relates to a manufacturing process for making such inductors. [Background technology]

[0002] Inductors establish the physical embodiment of an inductance element. Therefore, inductors are characterized not only by their inductance but also by resistive losses, which are generally undesirable. Correspondingly, the efficiency of circuit components that include inductors depends on the losses caused by passive components such as inductors. Therefore, what is desired is an inductor with reduced resistive losses.

[0003] Inductors can be manufactured using different methods. They can be made using copper structures such as copper wire and by bending the wire to obtain windings. Additionally, thin film technology can be used to make inductors.

[0004] However, there is a need for inductors that can improve the efficiency of corresponding electrical circuits and have reduced resistive losses. Furthermore, the corresponding inductors should have a reliable and mechanically stable coil structure. Furthermore, it is preferable that the inductors have a precisely defined inductance, which can be obtained, for example, by strictly following small deviations from the preferred shape of the coil structure. Furthermore, it is preferable that the inductors can be used as SMT-type inductors (SMT = Surface Mount Technology).

[0005] US Patent Nos. 9,490,062 and 10,014,102 disclose coil structures obtained by processes using thin-film technology. 3D printing, which can also be used to create inductors, is known from WO 02 / 07918 A1, US 6,117,612 A, and WO 2019 / 092193 A1. Fusion processes involving lasers or electron beams for processing thermoplastic compounds containing metal particles are known from WO 98 / 24574 A1 and WO 01 / 81031 A1.

[0006] However, it would be desirable to have an inductor with improved parameters compared to known inductors or inductors that can be manufactured with known processes. Summary of the Invention

[0007] To this end, an inductor is provided according to independent claim 1. The dependent claims provide preferred embodiments, manufacturing methods or uses of particular processes for manufacturing the inductor.

[0008] The inductor includes a first terminal and a second terminal. The inductor further includes a conductor between the first terminal and the second terminal. The first terminal, the conductor, and the second terminal form a monolithic structure.

[0009] In this inductor, the first and second terminals can establish a terminal that allows the inductor to be electrically connected to an external circuit environment. The conductor between the first and second terminals establishes the coil structure of the inductor. The fact that the first terminal, conductor, and second terminal establish a monolithic structure distinguishes the inductor from known inductors in which segments of the coil structure are soldered or welded to each other. The monolithic structure inherently reduces resistive losses, improves reliability, reduces porosity, and enables corresponding electrical circuits with improved energy efficiency.

[0010] The inductor may be derived via an electrochemical additive manufacturing process (ECAM).

[0011] The ECAM method allows the use of an in-situ control loop to adjust material deposition during the manufacturing process. ECAM is known from US 2021 / 0054516 A1 or US 2017 / 0145584 A1. By using ECAM to establish an inductor, it is possible to control the area and direction in which the material used for the inductor is deposited in the galvanic bath. For this purpose, a commonly used bottom cathode and independently operable anode segments positioned above the bottom cathode can be used. The anode segments are arranged in a matrix-like pattern with columns and rows and are actuated independently of each other.

[0012] Such an ECAM process allows the creation of monolithic inductors with terminals and conductors that establish a coil structure between the terminals. Furthermore, the use of the ECAM process allows for high precision in the corresponding conductor shape and eliminates deformation, since no heat treatment is required after the inductor is created. It also allows for the simultaneous creation of multiple inductors, resulting in a shorter process time per inductor compared to inductors obtained by printing followed by baking and sintering. Therefore, a more cost-effective solution is provided, as no intermediate drying process is required after printing.

[0013] A particular advantage of using the ECAM process is the high flexibility in defining the shape of the coil structure. Specifically, the ratio of conductors per volume can be maximized. Also, because only the individually actuatable anode segments need to be programmed, switching from one shape of the coil structure to another is possible in a short time.

[0014] Correspondingly, the inductor may have no welding or soldering points.

[0015] The inductor may have an outer periphery and a volume within the periphery. The first terminal, the second terminal, and the conductor establish a structure having a volume. The volume of the structure of the conductor and the first and second terminals is 60% or more, or 80% or more, of the outer periphery volume of the inductor. A preferred volume range is 60% to 80%. This allows for an increased filling rate. Therefore, for a given inductance, the corresponding inductor can be manufactured with a smaller spatial dimension and / or reduced weight.

[0016] Additionally, the reduced weight and smaller spatial dimensions also reduce the amount of chemicals required to establish the inductor, further reducing costs.

[0017] The periphery can have the shape of a rectangular parallelepiped or cube. This gives the inductor designer new degrees of freedom in designing the individual shapes of the inductors, allowing a greater degree of packing of different inductors within the external circuit environment. In fact, the degrees of freedom in designing the inductors are limited only by the resolution of the matrix containing the individually actuable anode segments.

[0018] The inductor may be an SMT inductor, which can be easily integrated into an external circuit environment, for example, on a circuit board having contact structures on the surface of the circuit board dedicated to connecting to the first terminal and the second terminal, respectively.

[0019] Furthermore, the conductor may comprise a primary constituent material selected from copper, aluminum, silver, gold, or another preferred material having high electrical conductivity, and the primary constituent material may have a purity equal to or greater than 90%, greater than 95%, greater than 98%, or greater than 99%.

[0020] The application of the main component materials in a galvanic bath makes it possible to easily obtain such high purity and substantially reduces porosity and resistance losses.

[0021] In particular, due to the greater freedom in designing the inductor, the conductor may have a cross section different from that of the wound wire, where wound wire usually has a disk cross section.

[0022] In particular, the conductor may have a cross section selected from square, rectangular, polygonal, circular, elliptical, and any combination of these shapes, or another shape that allows for a high degree of filling of the surrounding volume of the inductor without shorting out different coil windings.

[0023] Furthermore, the corresponding DC-DC converter may comprise an inductor as described above.

[0024] The DC-DC converter may be a high frequency DC-DC converter in which the inductor may be used in conjunction with other inductors or semiconductor switching devices to establish a voltage conversion function.

[0025] The method for manufacturing the above-described inductor may include an ECAM process.

[0026] That is, multiple inductors can be fabricated simultaneously.

[0027] Thus, the ECAM process can be used to fabricate one or more inductors.

[0028] The inductor conductor can have a rectangular coil primarily made of copper. Each turn of the coil can be characterized by a copper thickness, essentially limited only by the resolution of the matrix configuration of the anode segments. Typical values ​​for the smallest possible characteristic design feature are 10 μm to 300 μm, determined by the resolution of the matrix configuration. The coil can have characteristic dimensions of 100 μm to 10 mm for length, width, and height. To prevent short circuits, a space or gap must be provided between the windings. The size of the gap can range from 10 μm to 100 μm, also determined by the resolution of the matrix configuration. The coil structure can be molded with a magnetic material to further improve the parameter range of the desired inductance value, further improve mechanical stability, and improve the connection between the terminals and the PCB. The terminals can be provided with additional materials, such as silver, nickel, or tin, to strengthen the mechanical and electrical connection to the PCB. [Brief explanation of the drawings]

[0029] The detailed operating principle and central aspects of the preferred embodiment are illustrated in the accompanying schematic diagram.

[0030] [Figure 1] 1 is a perspective view of an inductor and a corresponding housing having an essentially rectangular parallelepiped shaped peripheral region; [Figure 2] 1 is a perspective view of an inductor and a corresponding housing having an essentially rectangular parallelepiped shaped peripheral region; [Figure 3] FIG. 1 is a perspective view of a circular inductor and a corresponding rectangular parallelepiped-shaped housing. [Figure 4] FIG. 10 is a top view of multiple inductors fabricated together before singulation. [Figure 5] FIG. 10 is a top view of a particular inductor shape with increased conductor thickness at the terminals. [Figure 6] 1A-1C illustrate different stages in fabricating an inductor using the ECAM process. [Figure 7]1A-1C illustrate different stages in fabricating an inductor using the ECAM process. [Figure 8] FIG. 10 illustrates the relationship between activated and non-activated matrix segments. [Figure 9] 1A-1C are perspective (top and bottom) and cross-sectional views of several alternatively shaped conductors. [Figure 10] FIG. 10 is a perspective view of a further possible shape in which the conductor winding has a polygonal shape. DETAILED DESCRIPTION OF THE INVENTION

[0031] 1 and 2 are perspective views showing the shape of a rectangular coil (FIG. 1) and a corresponding housing (FIG. 2), the main constituent material of which is, for example, copper.

[0032] The windings of the conductor that define the coil correspond to a frame that fits the different turns 1 and the terminals 2 that establish the connection area. Each turn of the coil 4 is characterized by a copper thickness, with typical values ​​for these characteristics ranging from 10 μm to 300 μm. The copper profile, i.e., the conductor, can have characteristic size parameters (width, length, height) ranging from 100 μm to 10 mm. The space or gap between the windings 3 should prevent short circuits between the windings; depending on the size of the component, the current gap value can be 10 to 100 μm. The copper frame 1 can be molded together with the magnetic material 5 to achieve the desired inductance of the formed inductor. The molding material can also directly define the inductor's housing.

[0033] To improve the connection between the coil and the mounting location, e.g., a PCB, a structured connection area 6, e.g., having silver (and / or nickel and / or tin), can be printed or deposited on the housing at the location of the terminal 2.

[0034] 3 and 4 provide alternative geometries illustrating the concept of a coil array 17, which may be created in a 3x3 configuration of simultaneously printed coils 10, but is not limited to this. The array of coils is not limited by the number of units, which may depend on the mechanical limitations of the manufacturing equipment. To provide good mechanical stability, the coils 10 are joined at four points 14, and each turn of the coil 13 is characterized by a copper thickness (e.g., 10 μm to 300 μm), with the copper profile having a size of 100 μm to 10 mm.

[0035] FIG. 5 shows the structure of the printed coil in plan view, and the manufacturing process steps are shown in FIGS.

[0036] Figure 6 shows the turns 28 of the plan view of Figure 5 in side view as elements / copper deposits 25. The elements 25 that later establish the turns 28 of Figure 5 are created by active anodes 25. Gaps form between the turns due to the lack of copper deposition by the inactive anode elements.

[0037] In Figure 6 (top), a preliminary step in the process of creating a coil using a galvanic bath with a selective copper deposition process can be seen: the cathode 20 is moving along the Z axis 48 at a speed that allows for a chemical reaction 47 (leading to deposition) between the active anode and cathode in the galvanic bath 26.

[0038] At the start of the process, the cathode 20 and anode 21 are in close proximity to allow copper structures to grow only in areas where the corresponding anode segment 25 is active. Copper 24 does not grow in areas where the anode is not active.

[0039] The bottom part of Figure 6 shows the stage where the cathode has already moved in the Z-axis to allow more copper growth in the active anode area.

[0040] In Figure 7, some of the active anode segments are disconnected to allow copper growth only in desired areas to form several copper protrusions 23. Thus, time-dependent selectivity of activity of different segments can be obtained, with deviations from translational symmetry in the vertical Z direction.

[0041] 8, the pitch 41 that may or may not be energized essentially defines the resolution of the resulting copper image. The pitch (and therefore the resolution) may be the same or different for different lateral directions.

[0042] Depending on the number of lateral dimensions 45, 46, larger or smaller copper structures can be produced.

[0043] Figure 9 shows an alternative form of module of four coils 36. Each single coil has four independent contacts 34 and one common connection point 35, and the complete module is molded in magnetic material 33. The connection areas 34 and 35 are covered by termination pads 31 and 32 implemented with printed deposits of silver (or nickel or tin), for example. The module can also be manufactured as an array with a common terminal 38, as shown in Figure 4.

[0044] FIG. 10 shows an alternative configuration for the manufactured coil 60. The copper structure 61 may be made in an array of coils, and is not limited to a 3×3 arrangement of coils. In this particular embodiment, the coil is formed in an axial rather than radial configuration, and the connection area with the PCB is formed in a copper block 61. To achieve low DC resistance, the thickness of this copper block 62 is increased to obtain the desired value. Gaps between different turns 63 can be covered with insulating material. The coil can be implemented with a different number of turns 64. The copper block can be molded with a magnetic material 69 to achieve the desired inductance value.

[0045] To improve the manufacturability of the coil, the product is made into a matrix 67 which can be molded as a block and through a cutting or dicing process to obtain single inductors.

[0046] List of Reference Numbers 1 Printed copper / conductor construction 2 Area for external connections 3. Gap between windings 4. Spiral structure 5 Metal material molding of structure 1 6. Contact area deposition on the area for external copper contact 2 10 Round Coil 11 Contact points of printed copper structure 12 Gap between windings 13 Spiral structure 14 Coil-to-coil contact for manufacturing with matrix concept 15 Contact area formed with silver paste, nickel barrier and tin alloy 16 Molded body 17 Array of premolded serially manufactured inductors 20 Cathode (-) 21 Anode Matrix 22 Copper deposition, winding section area formed by active anode 28 23 Copper deposition (contact areas require higher copper structures) 24 Unpowered anode (o) 25 Energized anode (+) 26 Electrolyte 27 Cross section of the coil shown in Figures 3b and 3c 28 Copper structural crate with energized anode 40 A 49x38 pixel matrix representing the anode of a galvanic bath 41 pixels representing the finest pitch of structures that can be active anodes 42 active anode area to form contact points for external connections 43 Inactive anode to form gap between turns 44 Active anode area to form the wound structure of Figure 3a 45, 46 The lateral dimension that (together with pitch) defines the lateral resolution 47 Activated anode that reacts with the cathode Cathode movement in Z direction to generate 48 structures 30 Coil with axial coils manufactured by 3D printing technology 31 Contact area formed with silver paste, nickel barrier and tin alloy 32 Coil common point, contact to PCB 33 Molded body containing metal material 34 Coil contact points 35 Commonalities among multi-inductors 36 Copper Block Bus 37 coil turns 38 Contact points between adjacent coils 39 Gaps between different turns (areas covered by insulating material) 60 Inductor with axial coil manufactured with ECAM printing technology 61 Copper block to form the connection area with the PCB 62 Inductor copper thickness to reduce RDC 63 Gaps between different turns 64 coil turns 65 Contact area formed with silver paste, nickel barrier and tin alloy 66 Winding start and end 67 Matrix of preformed series-manufactured inductors 68 Contact points between coils 69 Molded body containing metal material

Claims

1. It is an inductor, The first terminal and the second terminal, A conductor between the first terminal and the second terminal, The first terminal, the conductor, and the second terminal establish a monolithic structure. The conductor establishes a coil structure between the first terminal and the second terminal, The coil structure has windings, The coil structure includes a shape in which two adjacent windings are wound radially such that they have different outer circumferences. The windings are separated by the gaps between adjacent windings. An inductor in which the size of the aforementioned gap is in the range of 10 μm to 100 μm.

2. The inductor according to claim 1, wherein the inductor is derived via an electrochemical additive manufacturing (ECAM) process.

3. The ECAM process includes the use of a bottom cathode and an independently usable anode segment, The inductor according to claim 2, wherein the anode segments are arranged in a matrix-like pattern having columns and rows and operate independently of each other.

4. The inductor according to claim 1, wherein the inductor has no welding points or soldering points.

5. The inductor has an outer circumference and a volume within the outer circumference, The first terminal, the second terminal, and the conductor establish a structure having volume, The inductor according to claim 1, wherein the volume of the structure comprising the conductor and the first and second terminals is 60% to 80% or greater than the volume of the outer circumference of the inductor.

6. The inductor according to claim 5, wherein the outer circumference has the shape of a rectangular parallelepiped or a cube.

7. The inductor according to claim 1, wherein the inductor is an SMT type inductor.

8. The inductor according to claim 1, wherein the conductor comprises a main constituent material selected from copper, aluminum, silver, or gold, and the main constituent material has a purity equal to 90% or more, 95% or more, 98% or more, or 99% or more.

9. The inductor according to claim 1, wherein the conductor includes a cross-section different from that of the disk.

10. The inductor according to claim 1, wherein the conductor includes a cross-section selected from square, rectangular, polygonal, circular, elliptical, and all combinations thereof.

11. A DC-DC converter comprising the inductor described in Claim 1.

12. A method for manufacturing an inductor according to claim 1, wherein the method includes an ECAM process.

13. The method according to claim 12, wherein multiple inductors are manufactured simultaneously.

14. Use of an ECAM process for manufacturing one or more inductors.

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