Multilayer coil

Abstract

To provide a laminated coil that can secure a number of turns of 1.0 or more. [Solution] A laminated coil 10 is formed by stacking multiple connected cells 4a to 4f, wherein the cells 4a to 4f of the primary coil 1 have a through hole 43 formed in the center, a resin layer 44 made of an insulating material, a surface coil pattern 45 made of a conductive material formed on the surface of the resin layer 44, a back coil pattern 46 made of a conductive material formed on the back surface of the resin layer 44, a through via 47 that electrically connects the surface coil pattern 45 and the back coil pattern 46, and a connecting portion 48 that connects adjacent cells 4a to 4f and is bent to stack the cells 4a to 4f. The current path flowing through cells 4b to 4e has a total number of turns of 1.0 turn or more for the surface coil pattern 45 and the back coil pattern 46.

Description

Technical Field

[0001] The present invention relates to a laminated coil.

Background Art

[0002] Laminated coils are known in which insulating members such as ceramics and cells each having a coil pattern made of a conductive member are alternately stacked. A plurality of the cells are provided, and the plurality of cells are connected to each other via connecting portions. The cells are laminated by bending the connecting portions.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of Invention

Problems to be Solved by the Invention

[0004] As in Patent Document 1, if the connecting portions are only bent in the same direction, only 0.5 turns to 0.75 turns can be wound per layer. Therefore, the number of turns of the laminated coil cannot be secured.

[0005] The present invention has been made to solve the above problem, and an object thereof is to provide a laminated coil capable of securing a number of turns of 1.0 turns or more.

Means for Solving the Problems

[0006] The laminated coil of the present invention is a laminated coil formed by stacking a plurality of connected cells, wherein each cell has a through hole formed in the center, a resin layer made of an insulating material, a surface coil pattern made of a conductive material formed on the surface of the resin layer, a back coil pattern made of a conductive material formed on the back surface of the resin layer, through vias electrically connecting the surface coil pattern and the back coil pattern, and a connecting portion that connects adjacent cells and is bent to stack the cells, and the current path flowing through the cell is characterized in that the total number of turns of the surface coil pattern and the back coil pattern is 1.0 turn or more. [Effects of the Invention]

[0007] According to the present invention, it is possible to obtain a laminated coil that can secure a number of turns of 1.0 turn or more. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of a laminated coil according to the embodiment. [Figure 2] This is a schematic diagram of the primary coil showing the state before stacking each cell of the embodiment. [Figure 3] This is a plan view of the cell. [Figure 4] This is a cross-sectional view AA in Figure 3. [Figure 5] This is a schematic diagram of the secondary coil showing the state before each cell is stacked. [Figure 6] This is a schematic plan view of the primary coil showing the state after each cell has been stacked. [Figure 7] This is a schematic diagram showing the current path through each cell of the primary coil. [Figure 8] This diagram shows the current path flowing through the surface coil pattern of each cell. [Figure 9] This diagram shows the current path flowing through the coil pattern on the back of each cell. [Figure 10] This diagram shows the current path used to calculate the number of turns as 0.125. [Figure 11]This diagram shows the current path calculated to have 0.25 turns. [Figure 12] This diagram shows the current path calculated to have 0.50 turns. [Figure 13] This is a schematic diagram of the primary coil showing the state before stacking each cell in other embodiments. [Figure 14] This is a schematic diagram of the primary coil showing the state before stacking each cell in other embodiments. [Figure 15] This is a schematic diagram of the primary coil showing the state before stacking each cell in other embodiments. [Figure 16] This is a schematic diagram of the secondary coil showing the state before stacking each cell in other embodiments. [Figure 17] This is a schematic diagram of the secondary coil showing the state before stacking each cell in other embodiments. [Modes for carrying out the invention]

[0009] [Embodiment] The laminated coil in this embodiment will be described with reference to the drawings. Figure 1 is a schematic diagram of the laminated coil 10 of this embodiment. The laminated coil 10 comprises a primary coil 1, a secondary coil 2, and an insulating layer 3. The primary coil 1 and the secondary coil 2 each have a plurality of cells 4 and 5 that form one layer (see Figures 2 and 5), and the cells 4 of the primary coil 1 and the cells 5 of the secondary coil 2 are stacked alternately. An insulating layer 3 is provided between each layer of cells in the primary coil 1 and cells 5 in the secondary coil 2.

[0010] FIG. 2 is a schematic diagram of a primary coil showing a state before stacking the respective cells 4. As shown in FIG. 2, the primary coil 1 has a plurality of cells 4. In the present embodiment, the primary coil 1 has six cells 4a to 4f, but the number of the cells 4 is not limited thereto. The plurality of cells 4 are bent at connecting portions 48 described later, so that adjacent cells 4 face each other and are stacked. By bending the connecting portions 48 in this manner, the primary coil 1 in which the plurality of cells 4 are stacked is obtained. When the cells 4a to 4f are not distinguished, they are simply referred to as the cells 4. Further, in the present embodiment, in a state after the connecting portions 48 are bent to stack the cells 4, the cell 4 located at the uppermost layer is the cell 4f, and the cell 4 located at the lowermost layer is the cell 4a.

[0011] FIG. 3 is a plan view of the cell 4. FIG. 4 is an A-A cross-sectional view of FIG. 3. The cell 4 has a rectangular shape. That is, the cell 4 has a pair of long side portions 41 and a pair of short side portions 42. Each long side portion 41 has a longer side length than each short side portion 42. As shown in FIGS. 2, 3, and 4, the cell 4 has a through hole 43, a resin layer 44, a front layer coil pattern 45, a back layer coil pattern 46, a through via 47, a connecting portion 48, and a terminal portion 49. In FIG. 3, for convenience of description, the back layer coil pattern 46 is illustrated as being shifted from the front layer coil pattern 45, but in practice, the back layer coil pattern 46 overlaps the front layer coil pattern 45.

[0012] The through hole 43 is a hole formed at the center of the cell 4. A core (not shown) is inserted into this through hole 43. The through holes 43 of the respective cells 4 overlap each other in a state where the respective cells 4 are stacked.

[0013] Note that the core is made of a magnetic material, and for example, a dust core, a ferrite core, a laminated steel sheet, or a metal composite core can be used. The metal composite core refers to a magnetic material formed by kneading magnetic powder and resin and curing the resin. The core has, for example, a θ shape composed of three leg portions and a pair of yoke portions connecting the three leg portions. This θ-shaped core can be formed by combining two E-shaped core members, or by combining an E-shaped core member and an I-shaped core member. Then, of the three leg portions, the central leg disposed at the center is inserted into the through hole 43. Note that the shape of the core is not limited to the θ shape composed of three leg portions, and may be an annular shape composed of two leg portions. For example, two U-shaped core members may be joined to form the core. In this case, two laminated coils 10 may be prepared, and the laminated coils 10 each having a through hole 43 in the two leg portions may be mounted respectively.

[0014] The resin layer 44 is constituted by an insulating member. Examples of the insulating member include polyimide. However, the insulating member is not limited to polyimide, and may be any material that can insulate the front-layer coil pattern 45 and the back-layer coil pattern 46 and can be bent. For example, ceramic may be used for the portion excluding the connection portion 48. In this case, polyimide is used for the connection portion 48. The resin layer 44 is provided between the front-layer coil pattern 45 and the back-layer coil pattern 46. The resin layer 44 insulates the front-layer coil pattern 45 and the back-layer coil pattern 46. A through hole 43 is formed at the center of the resin layer 44, and the resin layer 44 has an annular shape. That is, the resin layer 44 has an annular surface.

[0015] The front-layer coil pattern 45 and the back-layer coil pattern 46 are constituted by a conductive member. For example, copper or aluminum can be cited as the conductive member constituting the front-layer coil pattern 45 and the back-layer coil pattern 46. In the present embodiment, the front-layer coil pattern 45 and the back-layer coil pattern 46 are constituted by copper.

[0016] The surface coil pattern 45 is provided on the surface of the resin layer 44. The surface of the resin layer 44 is one side of the annular surface of the resin layer 44, and the other side of the annular surface is called the back surface. The surface coil pattern 45 is ring-shaped so as to surround the through hole 43. However, the surface coil pattern 45 has unconnected portions 451 that are not connected (see Figure 8). The unconnected portions 451 are areas where the resin layer 44 is exposed and do not become a path for current to flow.

[0017] The back layer coil pattern 46 is provided on the back surface of the resin layer 44. The back layer coil pattern 46 is ring-shaped and is arranged to overlap with the front layer coil pattern 45 via the resin layer 44. However, the back layer coil pattern 46 also has unconnected portions 461 where the back layer coil pattern 46 is not connected (see Figure 9). The unconnected portions 461 are areas where the resin layer 44 is exposed and do not serve as a path for current to flow.

[0018] The surface coil pattern 45 and the back coil pattern 46 serve as paths for current flow. As will be described in detail later, in each cell 4, the number of turns in the surface coil pattern 45 and the back coil pattern 46 is 1.0 turn or more. Furthermore, it is preferable that the number of turns in the surface coil pattern 45 and the back coil pattern 46 in each cell 4 be 1.75 turns or less. By keeping it at 1.75 turns or less, the thickness of the surface coil pattern 45 and the back coil pattern 46 does not increase, and the size of the laminated coil 10 can be prevented from becoming larger.

[0019] The through via 47 electrically connects the surface coil pattern 45 and the back coil pattern 46. The through via 47 is a hole that penetrates from the surface to the back of the annular surface of the resin layer 44. The inner surface of the hole in the through via 47 is coated with a conductive material such as copper plating. Therefore, the through via 47 can allow current flowing from the surface coil pattern 45 to the back coil pattern 46, or current flowing from the back coil pattern 46 to the surface coil pattern 45.

[0020] The through vias 47 are located in the central part of the short side portion 42 of each cell 4. By providing the through vias 47 in the short side portion 42, when the core is inserted into the through hole 43 and the laminated coil 10 becomes a component of the reactor or transformer, it can be positioned so as not to overlap with the yoke portion of the core. There is one less through via 47 than the number of cells 4. Therefore, in this embodiment, the uppermost cell 4a does not have a through via 47. In other words, there is one through via 47 in each of the cells 4b to 4f.

[0021] The connection portion 48 connects adjacent cells 4. The connection portion 48 has a resin layer 44, a surface coil pattern 45, and a back coil pattern 46 formed on it. That is, even in the connection portion 48, the surface coil pattern 45 or the back coil pattern 46 can become a path for current to flow. Therefore, the connection portion 48 can make adjacent cells 4 conductive. In this way, current can flow from the uppermost cell 4f to the lowest cell 4a via the surface coil pattern 45, the back coil pattern 46, the through via 47, and the connection portion 48.

[0022] The connecting portion 48 is formed at one end or both ends of the surface coil pattern 45 or back coil pattern 46 of each cell 4. That is, one or two connecting portions 48 are provided in each cell 4. More specifically, when the cells 4 are stacked, the topmost and bottommost cells 4 have one connecting portion 48, and the cells 4 stacked between the topmost and bottommost layers have two connecting portions 48. In other words, in this embodiment, cells 4a and 4f have one connecting portion 48, and cells 4b to 4e have two connecting portions 48. By sequentially bending each connecting portion 48, the cells 4 are stacked to form a primary coil 1.

[0023] The connecting portion 48 has a horizontal folding portion 481 and a vertical folding portion 482. The horizontal folding portion 481 is provided on the long side portion 41 of cell 4 and connects the long side portion 41 of adjacent cell 4. The horizontal folding portion 481 is folded along the direction of extension of the long side portion 41 of cell 4. The vertical folding portion 482 is provided on the short side portion 42 of cell 4 and connects the short side portion 42 of adjacent cell 4. The vertical folding portion 482 is folded along the direction of extension of the short side portion 42 of cell 4.

[0024] The terminal section 49 connects to the terminals of an external device (not shown). The terminal section 49 is provided in the uppermost and lowermost cells 4. That is, the terminal section 49 is provided in cells 4a and 4f. More specifically, the terminal section 49 is provided on the short side portions 42 of cells 4a and 4f.

[0025] The terminal section 49 is electrically connected to the surface coil pattern 45 or the back coil pattern 46, and current supplied from an external device flows through the terminal section 49 to the surface coil pattern 45 or the back coil pattern 46. In this embodiment, the terminal section 49 provided on cell 4a is connected to the back coil pattern 46 of cell 4a. The terminal section 49 provided on cell 4f is connected to the surface coil pattern 45 of cell 4f.

[0026] Thus, each cell 4 is provided with two connection parts 48 or one connection part 48 and one terminal part 49. Furthermore, the two connection parts 48 or one connection part 48 and one terminal part 49 are not located on the same side within a single cell 4. That is, in cells 4b to 4e, which have two connection parts 48, one connection part 48 is located on the long side 41, and the other connection part 48 is located on the short side 42. Similarly, in cells 4a and 4f, which have one connection part 48 and one terminal part 49, the connection part 48 is located on the long side 41, and the terminal part 49 is located on the short side 42.

[0027] Figure 5 is a schematic diagram of the secondary coil 2 showing the state before each cell 5 is stacked. As shown in Figure 5, the secondary coil 2 has multiple cells 5. In this embodiment, the multiple cells 5 are not connected. The cells 5 of the secondary coil 2 have through holes of the same size as the through holes of the cells 4, and are stacked on the cells 4 of the primary coil 1 such that the through holes 43 of the cells 4 overlap. The cells 5 of the secondary coil 2 are positioned between the cells 4 of the primary coil 1. In the cells 5 of the secondary coil 2, although not shown in the figure, surface coil patterns and back coil patterns are formed on the resin layer and the annular surface of the resin layer, similar to the cells 4 of the primary coil 1.

[0028] As shown in Figure 1, the insulating layer 3 is provided between the cells 4 of the primary coil 1 and the cells 5 of the secondary coil 2. The insulating layer 3 insulates the cells 4 of the primary coil 1 from the cells 5 of the secondary coil 2. The insulating layer 3 is made of an insulating material. The insulating material can be the same type as the resin layer 44 of the primary coil 1.

[0029] Furthermore, the insulating layer 3 is provided so as to cover the entire surface of the cells 4 of the primary coil 1 and the cells 5 of the secondary coil 2. The insulating layer 3 insulates cells 4 and 5. The insulating layer 3 is ring-shaped and has holes of the same size as the through holes 43. The holes in this insulating layer 3 overlap with the through holes 43 of cell 4 and the through holes of cell 5. The insulating layer 3 may be larger than cells 4 and 5, but it is sufficient if it is at least the same size.

[0030] The insulating layer 3 is also provided between the through vias 47 of each cell 4. In this embodiment, when the cells 4 are stacked, a portion of the through vias 47 are arranged on the same plane (on an extended region perpendicular to the annular surface of the cell 4). Therefore, the insulating layer 3 provides insulation between the through vias 47.

[0031] Next, the method for manufacturing the laminated coil 10 will be explained. First, the insulating material constituting the insulating layer 3 is joined to the cell 4a of the primary coil 1 using an adhesive or the like. Then, the cell 5 of the secondary coil 2 is joined to the insulating layer 3 using an adhesive or the like. The insulating material constituting the insulating layer 3 is joined to the cell 5 of the secondary coil 2, and then the lateral folding portion 481 connecting cells 4a and 4b is folded along the extension direction of the long side portion 41. Hereafter, folding the lateral folding portion 481 along the extension direction of the long side portion 41 is referred to as lateral folding. Cell 4b is placed on the insulating layer 3, and the laminated cells 4a and 4b are stacked on the extension line of cell 4a so that the through holes 43 of each cell 4a and 4b overlap.

[0032] After the horizontal folding is complete and cell 4b is stacked on cell 4a, the process moves on to folding cell 4c. Similar to folding cell 4b, the insulating layer 3 and cell 5 of the secondary coil 2 are joined to cell 4b of the primary coil 1. Then, the vertical folding portion 482 connecting cell 4b and cell 4c is folded along the extension direction of the short side portion 42. Hereafter, folding the vertical folding portion 482 along the extension direction of the short side portion 42 is referred to as vertical folding. Cell 4c is placed on the insulating layer 3 and stacked on the extension line of cells 4a and 4b.

[0033] After the vertical folding is complete and cell 4c is stacked on cells 4a and 4b, the process moves on to folding cell 4d. Similar to cell 4b, cell 4d has the insulating layer 3 and the cell 5 of the secondary coil 2 joined together, and then, by horizontal folding, cell 4d is placed on the insulating layer 3 and stacked on the extension of cells 4a to 4c. Once the stacking of cell 4d is complete, the process moves on to folding cell 4e. As described above, first the insulating layer 3 and the cell 5 of the secondary coil 2 are joined together, and then, by vertical folding, cell 4e is placed on the insulating layer 3 and stacked on the extension of cells 4a to 4d. Finally, as described above for cell 4f, first the insulating layer 3 and the cell 5 of the secondary coil 2 are joined together, and the horizontal folding section 481 connecting cell 4e and cell 4f is folded horizontally, and cell 4f is stacked on cells 4a to 4e. In this way, the cells 4 of the primary coil 1 are stacked by repeatedly folding them horizontally and vertically in an alternating manner, thereby creating a stacked coil 10.

[0034] Figure 6 is a schematic plan view of the primary coil 1 after each cell has been stacked. As shown in Figure 6, the connection portion 48 of the primary coil, into which each cell 4 is stacked, is formed at three locations on each long side 41 and short side 42. The horizontal fold portion 481 connecting cell 4a and cell 4b and the horizontal fold portion 481 connecting cell 4e and cell 4f are formed on one of the long sides 41, and these two horizontal fold portions 481 are arranged on the same plane (on an extended region perpendicular to the annular surface of cell 4). The horizontal fold portion 481 connecting cell 4c and cell 4d is formed on the other long side 41. In addition, the vertical fold portion 482 connecting cell 4b and cell 4c and the vertical fold portion 482 connecting cell 4d and cell 4e are formed on one of the short sides 42, and these two vertical fold portions 482 are arranged on the same plane (on an extended region perpendicular to the annular surface of cell 4).

[0035] The current path of such a multilayer coil 10 will now be explained. Figure 7 is a schematic diagram showing the current path through each cell 4 of the primary coil 1. As shown in Figure 7, the current flows through each cell 4 in a counterclockwise direction (black arrows in Figure 7) or a clockwise direction (white arrows in Figure 7). The current alternates between counterclockwise and clockwise flow through each cell 4.

[0036] Figures 8 and 9 show the details of the current flow paths. Figure 8 shows the current flow paths through the surface coil patterns 45 of each cell 4a to 4f. Figure 9 shows the current flow paths through the back coil patterns 46 of each cell 4a to 4f.

[0037] Current is supplied from a terminal 49 provided on cell 4a. Since this terminal 49 is connected to the back layer coil pattern 46, the current supplied from the terminal 49 flows through the back layer coil pattern 46 of cell 4a and toward the lateral fold 481, as shown in Figure 9. The current that reaches the lateral fold 481 flows through the lateral fold 481 to the back layer coil pattern 46 of cell 4b, and flows through the through via 47, making a full circuit of the back layer coil pattern 46 of cell 4b, going through the long side 41, the short side 42, and the long side 41 again. Then, the current flows from the back layer coil pattern 46 of cell 4b to the surface layer coil pattern 45 via the through via 47. The current that flows through the surface layer coil pattern 45 flows toward the vertical fold 482, which is connected to the short side opposite the short side 42 on which the through via 47 is provided, as shown in Figure 8. Then, the vertical folding portion 482 allows current to flow from the surface coil pattern 45 of cell 4b to the surface coil pattern 45 of cell 4c.

[0038] The current flowing through the surface coil pattern 45 of cell 4c flows toward the through via 47. After flowing along the long side portion 41, the current flows from the surface coil pattern 45 of cell 4c to the back coil pattern 46 via the through via 47. The current flowing through the back coil pattern 46 of cell 4c flows toward the horizontal fold portion 481 provided on the long side portion 41, as shown in Figure 9. The current then flows from the back coil pattern 46 of cell 4c to the back coil pattern 46 of cell 4d via the horizontal fold portion 481. The current flowing through the back coil pattern 46 of cell 4d flows toward the through via 47.

[0039] Current flows from the back layer coil pattern 46 of cell 4d to the front layer coil pattern 45 via the through via 47. As shown in Figure 8, the current flowing through the front layer coil pattern 45 flows toward the vertical fold portion 482 provided on the short side portion 42, and through the vertical fold portion 482 flows from the front layer coil pattern 45 of cell 4d to the front layer coil pattern 45 of cell 4e. The current flowing through the front layer coil pattern 45 of cell 4e flows toward the through via 47, making a full circuit around cell 4e. Then, through the through via 47, it flows from the front layer coil pattern 45 of cell 4e to the back layer coil pattern 46.

[0040] As shown in Figure 9, the current flowing through the back layer coil pattern 46 of cell 4e flows toward the lateral fold portion 481 provided on the long side portion 41, and through the lateral fold portion 481, flows from the back layer coil pattern 46 of cell 4e to the back layer coil pattern 46 of cell 4f. The current flowing through the back layer coil pattern 46 of cell 4f flows toward the through via 47, making a full circuit around cell 4f. Then, through the through via 47, flows from the back layer coil pattern 46 of cell 4f to the surface layer coil pattern 45. As shown in Figure 8, the current flowing through the surface layer coil pattern 45 of cell 4f flows toward the terminal portion 49 provided on cell 4f.

[0041] The current follows the path described above. The current path through each cell 4b to 4e, which is sandwiched between the uppermost and lowermost layers, is at least one turn long when combined with the path of the surface coil pattern 45 and the path of the back coil pattern 46.

[0042] Here, the definition of a turn will be explained with reference to the diagram. Figure 10 shows a current path for which the number of turns is calculated to be 0.125. As shown in Figures 10(a) and (b), the number of turns is calculated to be 0.125 when the length of the current path is 1 / 2 or less of the length of the long side 41 or short side 42 of the surface coil pattern 45 or the back coil pattern 46.

[0043] Figure 11 shows the current path for which the number of turns is calculated to be 0.25. As shown in Figures 11(a) and (b), if the current path is the length of one side of the long side 41 or short side 42 of the surface coil pattern 45 or back coil pattern 46 (more specifically, if the length is longer than half the length of the long side 41 and short side 42 and extends to one side), the number of turns is calculated to be 0.25. Also, as shown in Figure 11(c), if the current path spans both sides of the long side 41 and short side 42, and the current path of the long side 41 and short side 42 is less than or equal to half the length of the long side 41 or short side 42 of the surface coil pattern 45 or back coil pattern 46, the number of turns is calculated to be 0.25.

[0044] Figure 12 shows the current path for which the number of turns is calculated to be 0.50. As shown in Figure 12(a), if the current path is one side of the short side 42 and the current path extending from both ends of that side to the long side 41 is 1 / 2 or less of the length of the long side 41, the number of turns is calculated to be 0.50. Also, as shown in Figure 12(b), if the current path is one side of the long side 41 and the current path extending from both ends of that side to the short side 42 is 1 / 2 or less of the length of the short side 42, the number of turns is calculated to be 0.50. Furthermore, as shown in Figure 12(c), if the current path is one side of the long side 41 (from a length longer than 1 / 2 of the long side 41 to the length of one side of the long side 41) and one side of the short side 42 (from a length longer than 1 / 2 of the short side 42 to the length of one side of the short side 42), the number of turns is calculated to be 0.50.

[0045] Based on the above rules for calculating the number of turns, the total number of turns of the surface coil pattern 45 and back coil pattern 46 of each cell 4b to 4e in this embodiment is calculated based on the current paths in Figures 8 and 9. In cell 4b of this embodiment, the current path from the through via 47 to the long side portion 41 in the surface coil pattern 45 is less than half the length of the short side portion 42, so as shown in Figure 10(b), the number of turns is "0.125". Also, the number of turns of the current path flowing through one side of the long side portion 41 and one side of the short side portion 42 is "0.50", as shown in Figure 12(c). Therefore, the total number of turns of the surface coil pattern 45 of cell 4b is "0.625".

[0046] On the other hand, in the back layer coil pattern 46 of cell 4b, the current path along one side of the long side 41 and one side of the short side 42 that connects to the lateral folded portion 481 connecting cell 4a and cell 4b has 0.50 turns, as shown in Figure 12(c). Also, the current path along one side of the long side 41 extending from the end of the short side 42 has 0.25 turns, as shown in Figure 11(a). Furthermore, the current path from the end of the long side 41 toward the through via 47 has 0.125 turns, as shown in Figure 10(b). Therefore, the total number of turns in the back layer coil pattern 46 of cell 4b is 0.825. Consequently, the total number of turns in the surface layer coil pattern 45 and the back layer coil pattern 46 of cell 4b is 1.5.

[0047] Next, calculating the number of turns in cell 4c, the current path flowing through the surface coil pattern 45 has 0.25 turns from the vertical fold 482 connected to cell 4b to one side of the long side 41, and 0.125 turns in the current path from the end of the long side 41 toward the through via 47. Therefore, the total number of turns in the surface coil pattern 45 of cell 4c is 0.375. On the other hand, in the back coil pattern 46, the current path from the through via 47 to the end of the short side 42 has 0.125 turns, and the number of turns in the current path along one side of the long side 41 and along one side of the short side toward the horizontal fold 481 from the end of the long side 41 is 0.50. Therefore, the total number of turns in the back coil pattern 46 of cell 4c is 0.625. Thus, the total number of turns in the surface coil pattern 45 and back coil pattern 46 of cell 4c is 1.0.

[0048] Similarly, the current paths of the surface coil pattern 45 of cell 4d are "0.125" and "0.5", the same as the surface coil pattern 45 of cell 4b and the back coil pattern 46 of cell 4c, resulting in a total of "0.625" turns. On the other hand, the current paths of the back coil pattern 46 are "0.25" and "0.125", the same as the surface coil pattern 45 of cell 4c, resulting in a total of "0.375" turns. Therefore, the total number of turns for the surface coil pattern 45 and back coil pattern 46 of cell 4d is "1.0".

[0049] Similarly, the current paths of the surface coil pattern 45 of cell 4e are "0.5", "0.25", and "0.125", similar to the number of turns of the back coil pattern 46 of cell 4b, totaling "0.875". On the other hand, the current paths of the back coil pattern 46 are "0.125" and "0.50", similar to the back coil pattern 46 of cell 4c, totaling "0.625". Therefore, the total number of turns for the surface coil pattern 45 and back coil pattern 46 of cell 4e is "1.5".

[0050] Thus, in cells 4b to 4e sandwiched between the uppermost and lowermost layers, the total number of turns that form the current path in the surface coil pattern 45 and the back coil pattern 46 is 1.0 or greater in all cases.

[0051] In this embodiment, the total number of turns of the surface coil pattern 45 and the back coil pattern 46 of cell 4f is 1.0 or more. The current path of the surface coil pattern 45 of cell 4f is the same as that of the surface coil pattern 45 of cell 4b, with a number of turns of "0.625", and the current path of the back coil pattern 46 is the same as that of the back coil pattern 46 of cell 4b, with a number of turns of "0.875". Therefore, the total number of turns of the surface coil pattern 45 and the back coil pattern 46 of cell 4f is "1.5".

[0052] [effect] As described above, the laminated coil 10 formed by stacking multiple cells 4a to 4f connected together in this embodiment has a through hole 43 formed in the center, a resin layer 44 made of an insulating material, a surface coil pattern 45 made of a conductive material formed on the surface of the resin layer 44, a back coil pattern 46 made of a conductive material formed on the back surface of the resin layer 44, and through vias 47 that electrically connect the surface coil pattern 45 and the back coil pattern 46, and the current path flowing through cells 4b to 4e has a total number of turns of 1.0 turn or more for the surface coil pattern 45 and the back coil pattern 46.

[0053] In this way, a surface coil pattern 45 and a back coil pattern 46 are provided on the surface and back of the resin layer 44, and the total number of turns of both, which form the current path, is set to 1.0 or more. Therefore, the number of turns of the laminated coil 10 can be ensured.

[0054] The current path flowing through cell 4 has a total of 1.75 turns or less, calculated from the surface coil pattern 45 and the back coil pattern 46.

[0055] For example, if the coil pattern is formed so that two or more current paths are formed in one layer, the thickness of each layer increases. As a result, the laminated coil becomes larger. Therefore, by keeping the number of turns to 1.75 or less, as in this embodiment, the number of turns can be secured without increasing the size of the laminated coil 10.

[0056] Cells 4a to 4f are further provided with connecting portions 48 that can be bent to connect adjacent cells 4a to 4f and to stack adjacent cells 4a to 4f. Cells 4a to 4f are rectangular in shape, and the connecting portions 48 are not located on the same side of each cell 4a to 4f. This allows each cell 4a to 4f to be stacked without interfering with each other.

[0057] Furthermore, some of the through-vias 47 are arranged on the same plane. Conventionally, in order to insulate the through-vias 47 provided in each cell 4, the through-vias 47 were arranged in each cell 4 so as not to be stacked on the same plane, which led to an increase in the size of the laminated coil 10. However, as in this embodiment, by interposing an insulating layer 3 between the through-vias 47, the through-vias 47 can be arranged on the same plane. As a result, the laminated coil 10 can be made smaller.

[0058] (Other embodiments) While embodiments of the present invention have been described herein, these embodiments are presented as examples and are not intended to limit the scope of the invention. The above embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the scope of the invention. Embodiments and their variations are included in the scope and essence of the invention, as well as in the claims and their equivalents.

[0059] In the above embodiment, the through via 47 was provided in the center of the short side portion 42, but the invention is not limited to this. Figure 13 is a schematic diagram of the primary coil showing the state before stacking each cell in another embodiment. The through via 47 may be provided, for example, in the long side portion 41 of cell 4e, as shown in Figure 13.

[0060] Furthermore, in the above embodiment, when stacking each cell 4 of the primary coil 1, horizontal and vertical folding were repeated alternately, but this is not limited to this. For example, as shown in Figure 13, cell 4d and cell 4e may be connected by a horizontal folding portion 481 instead of a vertical folding portion 482. That is, cells 4d to 4f may be stacked by continuously performing horizontal folding. In such a configuration, the number of turns of both the surface coil pattern 45 and the back coil pattern 46 of cell 4f will be "0.875", and the total number of turns will be "1.75".

[0061] Furthermore, as shown in Figures 14 and 15, the primary coil 1 may be constructed by arranging each cell 4a to 4f in a straight line and connecting the long sides 41 of each cell 4a to 4f only by the horizontal folding portion 481. In other words, the primary coil 1 may be stacked by horizontal folding only. In this case, the secondary coil 2 is provided with connecting portions 51 that connect each cell 5, as shown in Figures 16 and 17. Then, each cell 5 is arranged in a straight line, and the connecting portion 51 connects the short sides 52 of each cell 5. In other words, all connecting portions 51 are folded along the short sides 52, which is called vertical folding. In this way, even if the primary coil 1 is constructed using only horizontal folding and the secondary coil 2 using only vertical folding, the cells 4 of the primary coil 1 and the cells 5 of the secondary coil 2 can be stacked without interfering with each other. Note that the connection of the primary coil 1 and the secondary coil 2 may be reversed, so that the primary coil is constructed using only vertical folding and the secondary coil 2 is constructed using only horizontal folding.

[0062] Alternatively, the connection portion 48 of the primary coil 1 may be configured so that it is folded only horizontally, as shown in Figures 14 and 15, and the secondary coil 2 may be configured without being connected as in the embodiment. Alternatively, the connection portion 48 of the primary coil 1 may be configured so that it is folded only vertically, as shown in Figures 16 and 17, and the secondary coil 2 may be configured without being connected. Even in such cases, the cells 4 of the primary coil 1 and the cells 5 of the secondary coil 2 can be stacked without interfering with each other.

[0063] Furthermore, in the above embodiment, the primary coil 1 was folded horizontally and vertically alternately to stack each cell 4, but the secondary coil 2 may also be folded horizontally and vertically alternately. In this case, the cells 4 of the primary coil 1 are not connected, or the cells 4 are arranged in a straight line, and a connecting part 48 (horizontal folding part 481) is provided only on the long side 41 of each cell 4, and each cell 4 is stacked by horizontal folding only. [Explanation of symbols]

[0064] 10-layer coil 1. Primary coil 2. Secondary coil 3. Insulating layer 4 cells 41 Long side 42 Short side 43 Resin layer 44 Through holes 45 Surface coil pattern 451 Unconnected section 46. ​​Backing coil pattern 461 Unconnected section 47 Through via 48 Connection part 481 Horizontal fold section 482 Vertical fold section 49 Terminal section 5 cells 51 Connection part 52 Short side

Claims

1. A laminated coil made by stacking multiple connected cells, The aforementioned cell is A through hole formed in the center, A resin layer made of an insulating material, A surface coil pattern made of a conductive material is formed on the surface of the resin layer, A back layer coil pattern made of a conductive material is formed on the back surface of the resin layer, The surface coil pattern and the back coil pattern are electrically connected by through vias, A connecting portion that is bent to connect adjacent cells and to stack the cells, It has, The current path flowing through the cell has a total of 1.0 turn or more when the surface coil pattern and the back coil pattern are combined. A multilayer coil characterized by the following features.

2. The current path flowing through the cell has a total of 1.75 turns or less, including the surface coil pattern and the back coil pattern. A laminated coil according to claim 1, characterized by the following:

3. The cell is rectangular in shape, The aforementioned connecting portion is not provided on the same side within a single cell. A laminated coil according to claim 1 or 2, characterized by the above.

4. The cell has a pair of short sides and a pair of long sides that are longer than the short sides. The aforementioned connection part is A transverse fold portion that is bent along the direction of extension of the long side portion, A vertical fold portion that is bent along the direction of extension of the short side portion, It has, The stacked cells have alternating horizontal and vertical folded sections. A laminated coil according to claim 3, characterized by the above.

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