Manufacturing method of laminated coil component

Abstract

To provide a manufacturing method of a laminated coil component in which a mechanical strength of a coil is improved.SOLUTION: In a laminated coil component 10, a via conductor 26 that electrically connect coil layers 21 to 24 adjacent to each other in a stacking direction of an element body 12 protrudes from a coil region C toward side surfaces 12c to 12f of an element body 12 when viewed from the stacking direction of the element body 12. Therefore, the coil 20 is formed with a concave-convex part 28 in which a location of the via conductor 26 protrudes. When a force is externally applied to the laminated coil component 10 from the side surfaces 12c to 12f, for example, since the force is dispersed in the concave-convex part 28 of the coil 20, a defect is less likely to occur in the coil 20 as compared with a coil having the flat side surfaces 12c to 12f.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a laminated coil component. [Background technology]

[0002] Conventionally, there has been known a laminated coil component in which a coil having a coil axis parallel to the stacking direction is provided in an element body having a laminated structure. Patent Document 1 listed below discloses a technology for forming coil layers and via conductors that constitute the coil by a printing method. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-317308 Summary of the Invention [Problem to be solved by the invention]

[0004] In the laminated coil components according to the above-described prior art, when an external force is applied, the external force may reach the coil, causing defects in the coil.

[0005] As a result of extensive research, the inventors have discovered a new technology that increases the mechanical strength of a laminated coil component, thereby making it less likely for defects to occur in the coil even when an external force is applied to the laminated coil component.

[0006] An object of one aspect of the present invention is to provide a laminated coil component in which the mechanical strength of the coil is improved. [Means for solving the problem]

[0007] A laminated coil component according to one aspect of the present invention comprises: an element body including a plurality of stacked layers, the element body having a pair of end faces facing each other in a first direction parallel to the stacking direction of the plurality of layers, and a side surface connecting the pair of end faces; a coil provided within the element body and having a coil axis parallel to the first direction; and a pair of external electrodes provided on each end surface of the element body, the coil including a plurality of coil layers provided between the plurality of layers constituting the element body and aligned along the first direction; and a plurality of via conductors provided between adjacent coil layers in the first direction and electrically connecting the adjacent coil layers, the via conductors protruding from a coil region in which the coil layers are formed toward a side surface of the element body when viewed from the first direction.

[0008] In the above-described laminated coil component, the via conductors protrude from the coil region toward the side surfaces of the element body, and therefore uneven portions are formed at the locations of the via conductors. When an external force is applied to the laminated coil component, the force is dispersed at the uneven portions, making it less likely that defects will occur in the coil.

[0009] In a laminated coil component according to another aspect, the via conductor is formed of a plurality of conductor layers and has an uneven portion that is uneven in a direction perpendicular to the first direction.

[0010] In a laminated coil component according to another aspect, the conductor layers have a cross-sectional shape in which, in a cross section parallel to the first direction, two corners on one end face side of a rectangular element extending in a direction perpendicular to the first direction are rounded.

[0011] In a laminated coil component according to another aspect, the via conductors protrude from the coil region toward the side surfaces of the element body along the first direction, alternately on one side and the other side in a direction perpendicular to the first direction, in a cross section parallel to the first direction.

[0012] In a laminated coil component according to another aspect, the via conductors protrude from the coil region toward the side surfaces of the element body in a plurality of cross sections parallel to the first direction.

[0013] In a laminated coil component according to another aspect, the element body is a sintered element body. [Effects of the Invention]

[0014] According to various aspects of the present invention, a laminated coil component is provided in which the mechanical strength of the coil is improved. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a perspective view showing a laminated coil component according to an embodiment. [Figure 2] FIG. 2 is an exploded perspective view showing a stacked state of the element bodies shown in FIG. [Figure 3] 3 is a cross-sectional view of the element body shown in FIG. 2 taken along line III-III. [Figure 4] 4 is a plan view showing coil layers that constitute the coil shown in FIG. 3. FIG. [Figure 5] 3A to 3C are diagrams showing the steps in manufacturing the element body. [Figure 6] 3A to 3C are diagrams showing the steps in manufacturing the element body. [Figure 7] 3A to 3C are diagrams showing the steps in manufacturing the element body. [Figure 8] 3A to 3C are diagrams showing the steps in manufacturing the element body. [Figure 9] 3A to 3C are diagrams showing the steps in manufacturing the element body. [Figure 10] 3A to 3C are diagrams showing the steps in manufacturing the element body. [Figure 11] 3A to 3C are diagrams showing the steps in manufacturing the element body. [Figure 12] 3A to 3C are diagrams showing the steps in manufacturing the element body. [Figure 13] 10A and 10B are diagrams showing the positional relationship between a coil formation region and via conductors. [Figure 14] FIG. 2 is a diagram schematically illustrating the cross-sectional shape of a coil. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same or equivalent elements are designated by the same reference numerals, and redundant explanations will be omitted.

[0017] The configuration of a laminated coil component according to an embodiment will be described with reference to Figures 1 to 3. As shown in Figure 1, a laminated coil component 10 according to an embodiment is configured to include an element body 12 and a pair of external electrodes 14A, 14B.

[0018] The element body 12 has a substantially rectangular parallelepiped outer shape and a pair of end faces 12a, 12b facing each other in the extension direction of the element body 12. The element body 12 further has four side faces 12c to 12f that extend in the opposing direction of the end faces 12a, 12b and connect the end faces 12a, 12b. In this embodiment, the side face 12d is the mounting face that faces the mounting substrate when the laminated coil component 10 is mounted, and the side face 12c facing the side face 12d becomes the top face when mounted. The dimensions of the element body 12 are, for example, length 1.6 mm × width 0.8 mm × thickness 0.8 mm, where length is the dimension in the opposing direction of the end faces 12a, 12b, width is the dimension in the opposing direction of the side faces 12e, 12f, and thickness is the dimension in the opposing direction of the side faces 12c, 12d.

[0019] A pair of external electrodes 14A, 14B are provided on the end faces 12a, 12b of the element body 12, respectively. In this embodiment, the external electrode 14A integrally covers the entire area of ​​the end face 12a and the side faces 12c to 12f in the area adjacent to the end face 12a. Similarly, the external electrode 14B integrally covers the entire area of ​​the end face 12b and the side faces 12c to 12f in the area adjacent to the end face 12b. Each of the external electrodes 14A, 14B is composed of one or more electrode layers. The electrode material for each of the external electrodes 14A, 14B can be a metal material such as Ag.

[0020] The element body 12 has a configuration in which an internal conductor 18 is provided inside a magnetic body 16. The element body 12 has a layered structure. The magnetic body 16 has a layered structure in which multiple magnetic layers 17 are layered in the opposing direction of the end faces 12a, 12b. In the following description, the opposing direction of the end faces 12a, 12b is also referred to as the layering direction or first direction of the element body 12.

[0021] The magnetic body 16 is made of a magnetic material such as ferrite. The magnetic body 16 is obtained by stacking and firing a plurality of magnetic pastes (e.g., ferrite paste) that become the magnetic layers 17. In other words, the element body 12 has a printed laminated structure in which magnetic layers 17, on which magnetic pastes are printed, are stacked, and is a fired element body in which the fired magnetic layers 17 are stacked. The number of magnetic layers 17 that make up the element body 12 is, for example, 120. The thickness of each magnetic layer 17 is, for example, 15 μm. In the actual element body 12, the plurality of magnetic layers 17 are integrated to the extent that the boundaries between the layers are not visible.

[0022] The internal conductor 18 is configured to include one coil 20 and a pair of lead conductors 19 A, 19 B. The coil 20 and lead conductors 19 A, 19 B of the internal conductor 18 each have a layered structure in the layering direction of the element body 12.

[0023] As shown in Fig. 3, the coil 20 has a coil axis Z parallel to the lamination direction of the element body 12, and is wound around the coil axis Z. In this embodiment, the length of the coil 20 in the lamination direction of the element body 12 is 1.3 mm. With respect to the lamination direction of the element body 12, the length of the coil 20 can be designed to be in the range of 50 to 80% of the length of the element body 12. In this embodiment, the inner diameter of the coil 20 is 0.25 to 0.45 mm, for example 0.3 mm.

[0024] In this embodiment, the coil 20 includes four types of coil layers 21 to 24 as shown in FIG. 4. The coil layers 21 to 24 constituting the coil 20 are made of a conductive material containing a metal such as Ag. The coil 20 is formed by a printing method. Specifically, the coil 20 is obtained by applying a conductive paste (for example, Ag paste) that will become the coil layers 21 to 24 onto a magnetic paste that will become the magnetic layer 17, and then firing the applied paste. The thickness of each of the coil layers 21 to 24 is, for example, 30 μm.

[0025] Coil layers 21 to 24 are all U-shaped when viewed from the stacking direction of element body 12, and constitute 3 / 4 turns of coil 20. When viewed from the stacking direction of element body 12, coil layer 21 has a rotationally symmetric relationship with coil layer 22 about coil axis Z, and they completely overlap when coil layer 22 is rotated 90 degrees clockwise about coil axis Z. Coil layer 22 is located above coil layer 21, and one end 22a is electrically connected to end 21b of coil layer 21 via via conductors 26, which will be described later.

[0026] Coil layer 22 has a rotationally symmetric relationship with coil layer 23 about coil axis Z, and is substantially aligned when coil layer 23 is rotated 90 degrees clockwise about coil axis Z. Coil layer 23 is located above coil layer 22, and one end 23a is electrically connected to end 22b of coil layer 22 via via conductors 26 described below.

[0027] Coil layer 23 has a rotationally symmetric relationship with coil layer 24 about coil axis Z, and they completely overlap when coil layer 24 is rotated 90 degrees clockwise about coil axis Z. Coil layer 24 is located above coil layer 23, and one end 24a is electrically connected to end 23b of coil layer 23 via via conductors 26 described below.

[0028] Coil layer 24 has a rotationally symmetric relationship with coil layer 21 about coil axis Z, and they completely overlap when coil layer 21 is rotated 90 degrees clockwise about coil axis Z. Coil layer 21 is located above coil layer 24, and one end 21a is electrically connected to end 24b of coil layer 24 through via conductors 26 described below.

[0029] A set of coil layers 21-24 arranged in order in the stacking direction of element body 12 have their ends overlapping and joined together to form three turns of coil 20 surrounding coil axis Z. In this embodiment, coil 20 includes multiple sets of coil layers 21-24.

[0030] The coil 20 further includes a plurality of via conductors 26. Each via conductor 26 connects adjacent coil layers 21 to 24 in the stacking direction. Each via conductor 26 is made up of a plurality of stacked conductor layers 25, and in this embodiment, is made up of two conductor layers 25. Like the coil layers 21 to 24, the conductor layers 25 that make up the via conductor 26 are made up of a conductive material containing a metal such as Ag. Each via conductor 26 is formed by a printing method. Specifically, each via conductor 26 is obtained by applying a conductive paste (for example, Ag paste) that will become the conductor layer 25 onto a conductive paste that will become the coil layers 21 to 24, and then firing the paste.

[0031] The multiple via conductors 26 all have the same shape and dimensions. As shown in Fig. 4, the via conductors 26 have a rounded square shape with four rounded corners when viewed in the stacking direction of the element body 12. The length of each side of the via conductors 26 is designed to be wider than the width of each of the coil layers 21 to 24, and the formation area of ​​the via conductors 26 is wider than the formation area of ​​the coil end portions. Furthermore, when the via conductors 26 are placed on the end portions 21b, 22b, 23b, and 24b of each of the coil layers 21 to 24, they are placed so as to protrude in the extension direction of the end portions 21b, 22b, 23b, and 24b of each of the coil layers 21 to 24.

[0032] The via conductors 26 constituting each via conductor 26 all have the same shape and the same dimensions. As shown in Fig. 3, in a cross section parallel to the coil axis Z, the conductor layer 25 has a rectangular cross section extending parallel to the end faces 12a and 12b of the element body 12, with the two corners on the end face 12a side rounded (a so-called semi-cylindrical cross section). The thickness of each conductor layer 25 is, for example, 30 µm. In each via conductor 26, the multiple conductor layers 25 form an uneven portion 27 (see Fig. 10) that is uneven in a direction perpendicular to the stacking direction of the element body 12 (i.e., in the direction of the side faces 12c to 12f of the element body 12).

[0033] 5 to 12 show the procedure for forming a part of the coil 20 by the printing method.

[0034] As shown in FIGS. 5(a) and 5(b), first, a conductive paste that will become the coil layer 22 is printed on the magnetic layer 17 that will become the base.

[0035] 6(a) and 6(b), a magnetic paste that will become the magnetic layer 17 is printed so as to completely surround the periphery of the coil layer 22. This makes the surface of the laminate approximately flat.

[0036] 7(a) and 7(b), a conductive paste that will become the first conductor layer 25 is printed on the end 22b of the coil layer 22 that is exposed on the surface of the laminate. At this time, since the conductor layer 25 is larger in size than the end 22b of the coil layer 22, the conductor layer 25 protrudes outward from the end 22b of the coil layer 22 as shown in FIG. 7(b).

[0037] 8(a) and 8(b), a magnetic paste that will become the magnetic layer 17 is printed so as to completely surround the periphery of the first conductor layer 25. This causes the surface of the laminate to become approximately flat again.

[0038] 9(a) and 9(b), a conductive paste that will become the second conductor layer 25 is printed so as to overlap the first conductor layer 25. This forms a via conductor 26 with a two-layer structure.

[0039] 10(a) and 10(b), a magnetic paste that will become the magnetic layer 17 is printed so as to completely surround the periphery of the second conductor layer 25. This causes the surface of the laminate to become approximately flat again.

[0040] 11(a) and 11(b), a conductive paste that will become the coil layer 23 is printed. At this time, the end 23a of the coil layer 23 overlaps the via conductor 26, and the coil layer 22 and the coil layer 23 are electrically connected via the via conductor 26.

[0041] 12(a) and 12(b), a magnetic paste that will become the magnetic layer 17 is printed so as to completely surround the periphery of the coil layer 23. This causes the surface of the laminate to become approximately flat again.

[0042] 5 to 12 show the procedure for providing the coil layer 23 on the coil layer 22 via the via conductors 26, but the coil layers 21 to 24 can all be provided by the same procedure as above.

[0043] The sequentially stacked coil layers 21-24 form a rectangular, annular coil region C as shown in Fig. 13 when viewed from the stacking direction of the element body 12. Multiple via conductors 26 provided on the coil layers 21-24 are located at any of the four corners of the coil region C. As described above, each via conductor 26 is provided to protrude from the ends 21b, 22b, 23b, and 24b of the coil layers 21-24, and therefore protrudes from the inside to the outside of the line (i.e., the contour line) C1 that defines the outline of the coil region C. As a result, each via conductor 26 protrudes from the coil region C toward each of the side surfaces 12c-12f of the element body 12 when viewed from the stacking direction of the element body 12. In this case, each via conductor 26 includes an overlapping portion 26a located within the coil region C (i.e., overlapping with the coil layers 21 to 24) and a non-overlapping portion 26b located between the coil region C and the side surfaces 12c to 12f of the base body 12 (i.e., not overlapping with the coil layers 21 to 24), and the overlapping portion 26a and the non-overlapping portion 26b are integrated.

[0044] 14, in a cross section parallel to the coil axis Z, the via conductors 26 protrude further toward the side surfaces 12c to 12f of the element body 12 than the coil layers 21 to 24. Therefore, the coil 20 as a whole has an uneven portion 28 that is uneven in a direction perpendicular to the stacking direction of the element body 12 (i.e., in the direction of the side surfaces 12c to 12f of the element body 12). The uneven portion 28 of the coil 20 is uneven on all four surfaces, i.e., the side surfaces 12c to 12f of the element body 12. The uneven portion 28 of the coil 20 reaches the lead conductors 19A, 19B. Note that, as shown in FIG. 14, on the opposing side surfaces 12e, 12f, the positions of the peaks and valleys of the uneven portion 28 facing the side surface 12e and the uneven portion 28 facing the side surface 12f are misaligned. More specifically, the via conductors 26 extend along the stacking direction of the element body 12, alternately protruding toward the side surface 12e and the side surface 12f in the opposing direction of the side surfaces 12e and 12f, and protruding beyond the contour line C1 of the coil region C.

[0045] As described above, the laminated coil component 10 includes an element body 12 including a plurality of stacked magnetic layers 17 and having a pair of end faces 12a, 12b facing each other in a first direction parallel to the stacking direction of the magnetic layers 17, a coil 20 provided within the element body 12 and having a coil axis Z parallel to the first direction, and a pair of external electrodes 14A, 14B provided on the end faces 12a, 12b of the element body 12, respectively. The coil 20 includes a plurality of coil layers 21-24 provided between the magnetic layers 17 constituting the element body 12 and aligned along the first direction, and a plurality of via conductors 26 provided between adjacent coil layers 21-24 in the first direction and electrically connecting the adjacent coil layers 21-24. When viewed from the first direction, the via conductors 26 extend beyond the contour line C1 of the coil region C in which the coil layers 21-24 are formed.

[0046] 14, the coil 20 has uneven portions 28 where the via conductors 26 protrude. When an external force is applied to the laminated coil component 10, for example, from the side surfaces 12c to 12f, the force is dispersed in the uneven portions 28 of the coil 20, making it difficult for stress to propagate, and therefore the coil 20 is less likely to have defects than a coil whose side surfaces 12c to 12f are flat. That is, the mechanical strength of the coil 20 is improved in the laminated coil component 10.

[0047] Furthermore, in the laminated coil component 10, the via conductors 26 formed of the multiple conductor layers 25 have uneven portions 27. Like the uneven portions 28 of the coil 20, the uneven portions 27 of the via conductors 26 also have the function of dispersing external forces from the side surfaces 12c to 12f. That is, the uneven portions 27 of the via conductors 26 further improve the mechanical strength of the coil 20. In addition, the protrusions of the uneven portions 27 of the via conductors 26 act as wedges that engage with the magnetic layers 17, thereby suppressing shrinkage of the via conductors 26 (shrinkage relative to the magnetic layers 17) during firing of the element body 12. This makes it possible to suppress breakage of the via conductors 26.

[0048] Furthermore, in the laminated coil component 10, the via conductors 26 protrude from the contour line C1 of the coil region C not only in a cross section parallel to the side surfaces 12c and 12d as shown in Fig. 14 but also in a cross section parallel to the side surfaces 12e and 12f. Therefore, even if an external force is applied from any of the side surfaces 12c to 12f of the element body 12, the force can be dispersed in the uneven portion 28 of the coil 20.

[0049] Although the embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0050] For example, the shape of the coil region C may be a polygonal ring, a circular ring, or an elliptical ring. The planar shape of the via conductor 26 may be a polygonal, a circular, or an elliptical shape. The number of conductor layers 25 constituting the via conductor 26 may be one layer, or three or more layers. The cross-sectional shape of the conductor layer 25 constituting the via conductor 26 may be a semicircular cross section or a semielliptical cross section with the end face 12b side being flat. [Explanation of symbols]

[0051] 10... multilayer coil component, 12... element body, 12a, 12b... end faces, 12c to 12f... side faces, 14A, 14B... external electrodes, 17... magnetic layer, 20... coil, 21 to 24... coil layers, 25... conductor layer, 26... via conductor, 27... uneven portion, 28... uneven portion, C... coil region, Z... coil axis

Claims

1. A method for manufacturing a laminated coil component comprising: a first coil layer and a second coil layer that constitute a part of a coil inside a magnetic base body and are aligned along a coil axis of the coil; and a via conductor that is provided between the first coil layer and the second coil layer and electrically connects the first coil layer and the second coil layer, a first step of printing a first conductive paste that will become the first coil layer; a second step of printing a first magnetic paste around the first conductive paste, the first magnetic paste becoming a part of the magnetic element; A method for manufacturing a laminated coil component, comprising:

2. a third step of printing a second conductive paste to be the via conductor on an end of the first conductive paste after the second step; a fourth step of printing a second magnetic paste around the second conductive paste to become part of the magnetic element; The method for producing a laminated coil component according to claim 1 , further comprising:

3. The method for manufacturing a laminated coil component according to claim 2 , wherein after the second step, the third step and the fourth step are repeated in this order a plurality of times.

4. The method for manufacturing a laminated coil component according to claim 2 , wherein the second conductive paste is wider than the end of the first conductive paste.

5. a fifth step of printing a third conductive paste that will become the second coil layer after the fourth step; a sixth step of printing a third magnetic paste around the third conductive paste, the third magnetic paste becoming a part of the magnetic element; The method for producing a laminated coil component according to claim 2 , further comprising:

6. The method for manufacturing a laminated coil component according to claim 5 , wherein the second conductive paste is wider than the end of the third conductive paste.

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