Electronic components and their manufacturing method

Abstract

The present invention provides an electronic component that is capable of reducing stress applied to an element due to flexibility in a substrate, while suppressing an increase in direct current resistance. The electronic component comprises an element and an external electrode provided to the element, wherein: the element is provided with a first end surface, a second end surface that is opposite from the first end surface, and a bottom surface that is perpendicular to the first end surface and the second end surface; the external electrode is provided with a first external electrode that is provided to the first end surface side and a second external electrode that is provided to the second end surface side; the first external electrode is provided with a metal electrode that is provided to at least a part of the bottom surface and a resin electrode that covers a part of the portion of the metal electrode which is provided to the bottom surface; and on the bottom surface, the metal electrode has an exposed portion that is exposed from the resin electrode.

Description

[Technical Field]

[0001] The present invention relates to an electronic component and a method for manufacturing the same. [Background technology]

[0002] A conventional coil component is described in JP 2021-40160 A (Patent Document 1). This coil component has an element body and an external electrode provided on the surface of the element body. The external electrode comprises a metal electrode and a resin electrode that covers the entire surface of the metal electrode. In this case, taking into account an increase in DC resistance, the resin electrode is provided so that the end portion is thick and the remaining portion is thinner. This relieves stress and suppresses the occurrence of cracks. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-40160 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the coil component, the high-resistance resin electrode covers the entire surface of the metal electrode, so the effect of reducing DC resistance is insufficient. In addition, it is difficult to precisely identify the DC flow path in the coil component, and it is difficult to reduce DC resistance by adjusting the thickness of the resin electrode.

[0005] An object of the present disclosure is to provide an electronic component that can reduce deflection stress while suppressing an increase in DC resistance, and a method for manufacturing the same. [Means for solving the problem]

[0006] In order to solve the above problems, an electronic component according to one aspect of the present disclosure comprises: The base body and an external electrode provided on the element body, The element body is A first end surface; a second end surface facing the first end surface; a bottom surface perpendicular to the first end surface and the second end surface, The external electrode is a first external electrode provided on the first end surface side; a second external electrode provided on the second end surface side, The first external electrode is a metal electrode provided on at least a portion of the bottom surface; a resin electrode that covers a part of the portion of the metal electrode that is provided on the bottom surface, On the bottom surface, the metal electrode has an exposed portion that is exposed from the resin electrode.

[0007] The exposed portion of the metal electrode is the portion of the metal electrode that is not covered with the resin electrode. The exposed portion includes not only the portion of the metal electrode that is exposed to the outside, but also the portion that is covered with a material other than the resin electrode, such as a metal film or a plating layer.

[0008] According to the embodiment, only a portion of the metal electrode provided on the bottom surface is covered by the resin electrode. Therefore, when an electronic component is mounted on the bottom surface, the stress applied to the element body due to bending of the substrate (hereinafter referred to as bending stress) can be reduced while suppressing an increase in DC resistance due to the provision of the resin electrode.

[0009] In one embodiment, the electronic component further includes a plating layer on the bottom surface that covers at least a portion of the first external electrode.

[0010] According to the embodiment, when the electronic component is mounted on the bottom side, the electronic component is soldered via the plating layer, which improves adhesion. Furthermore, the plating layer prevents the solder from penetrating into the electronic component.

[0011] In one embodiment, the direction in which the first end surface and the second end surface face each other is referred to as an L direction, and The direction perpendicular to the L direction on the bottom surface is defined as the W direction, On the bottom surface, The exposed portion and the resin electrode are arranged side by side in the W direction.

[0012] According to the above embodiment, the deflection stress is further reduced.

[0013] In one embodiment, the direction in which the first end surface and the second end surface face each other is referred to as an L direction, and The direction perpendicular to the L direction on the bottom surface is defined as the W direction, The exposed portions are provided on both ends of the bottom surface in the W direction.

[0014] In one embodiment, the direction in which the first end surface and the second end surface face each other is referred to as an L direction, and The direction perpendicular to the L direction on the bottom surface is defined as the W direction, On the bottom surface, The resin electrodes are provided so as to sandwich the exposed portion from both sides in the W direction.

[0015] According to the embodiment, it is possible to increase the number of current paths that do not pass through the resin electrodes, and the increase in DC resistance is further suppressed.

[0016] In one embodiment, the bottom surface The maximum width of the resin electrode in the W direction is greater than the maximum width of the exposed portion adjacent to the resin electrode in the W direction.

[0017] According to the above embodiment, the deflection stress is further reduced.

[0018] In one embodiment, the bottom surface The maximum width of the exposed portion sandwiched between the two resin electrodes is 10 μm or more and 160 μm or less.

[0019] According to the embodiment, it is easy to balance the effect of reducing the deflection stress and the effect of suppressing an increase in DC resistance.

[0020] In one aspect, In the first external electrode, the metal electrode is further provided on a portion of at least one of the first end surface and the second end surface, The resin electrode further covers a part of the metal electrode provided on at least one of the first end face and the second end face.

[0021] According to the above embodiment, the deflection stress is further reduced.

[0022] In one aspect, The direction in which the first end surface and the second end surface face each other is called the L direction. The direction perpendicular to the L direction on the bottom surface is the W direction, and The direction perpendicular to both the L direction and the W direction is defined as the T direction, In the first external electrode, The resin electrode provided on a portion of at least one of the first end face and the second end face is provided in a region of the end face on which the resin electrode is provided, from the bottom side to 1 / 2 of the height of the element body in the T direction.

[0023] According to the embodiment, when the electronic component is mounted on the bottom surface side, the DC resistance can be further reduced while maintaining the effect of reducing the deflection stress.

[0024] In one aspect, The direction in which the first end surface and the second end surface face each other is called the L direction. The direction perpendicular to the L direction on the bottom surface is the W direction, and The direction perpendicular to both the L direction and the W direction is defined as the T direction, The resin electrode provided on the bottom surface protrudes outward in the T direction from the surface of the metal electrode provided on the bottom surface.

[0025] According to the above embodiment, when an electronic component is mounted on the bottom side, solder can penetrate into the irregularities formed by the resin electrodes, improving the connection strength between the circuit board and the electronic component. The plating layer also becomes less likely to peel off because solder can penetrate into the irregularities formed by the resin electrodes.

[0026] In one embodiment, the electronic component further includes a metal film that covers at least an exposed portion of the metal electrode that is exposed from the resin electrode.

[0027] According to the embodiment, it is possible to increase the number of current paths that do not pass through the resin electrodes, and the increase in DC resistance is further suppressed.

[0028] In one embodiment, at least on the bottom surface, the surface of the resin electrode and the surface of the metal film are flush with each other.

[0029] According to the embodiment, when an electronic component is mounted on the bottom surface side, the displacement or tilt of the electronic component is reduced, and the electronic component is mounted with high precision.

[0030] In one embodiment, the resin electrode provided on the bottom surface is symmetrical with respect to a line that passes through the center of the bottom surface and extends in an L direction in which the first end surface and the second end surface face each other. In one embodiment, the resin electrode provided on the bottom surface has a uniform thickness.

[0031] According to the embodiment, when the electronic component is mounted on the bottom side, rattle and tilt of the electronic component are reduced.

[0032] In one aspect, The direction in which the first end surface and the second end surface face each other is called the L direction. The direction perpendicular to the L direction on the bottom surface is the W direction, and The direction perpendicular to both the L direction and the W direction is defined as the T direction, In a cross section of the resin electrode, the cross section is parallel to a TW plane formed by a line extending in the W direction and a line extending in the T direction, The width of a first surface of the resin electrode provided on the bottom surface on the metal electrode side is narrower than the width of a second surface of the resin electrode on the opposite side to the first surface.

[0033] According to the above embodiment, peeling of the plating layer from the contact portion between the metal electrode and the resin electrode is suppressed, and in addition, the anchor effect acts to improve the bonding strength between the circuit board and the electronic component by soldering.

[0034] In one embodiment, the electronic component may further include a coil provided inside the element body, the coil being electrically connected to the first external electrode and the second external electrode.

[0035] According to the embodiment, an increase in DC resistance is suppressed, and therefore, even in a coil component through which a large current may flow, heat generation and the like can be suppressed while the bending stress can be reduced.

[0036] Furthermore, a method for manufacturing an electronic component according to one aspect of the present disclosure includes: preparing an element body having a first end surface, a second end surface opposite to the first end surface, and a bottom surface perpendicular to the first end surface and the second end surface; providing a first external electrode on the first end surface side; and providing a second external electrode on the second end surface side. The step of providing the first external electrode includes: forming a metal electrode on at least a portion of the bottom surface on the first end face side; forming a resin electrode that covers a portion of the portion of the metal electrode that is provided on the bottom surface; In the step of forming the resin electrode, an exposed portion of the metal electrode that is exposed from the resin electrode is formed.

[0037] According to the embodiment, in an electronic component including a metal electrode and a resin electrode, an exposed portion of the metal electrode that is exposed from the resin electrode can be formed.

[0038] The step of forming the resin electrode includes: applying a conductive resin composition containing a photosensitive resin to at least a portion of the portion of the metal electrode provided on the bottom surface; irradiating a portion of the applied resin composition with laser light; The method may further comprise the step of removing the part or remainder of the resin composition after the irradiating step.

[0039] According to the embodiment, a resin electrode having a desired shape and thickness can be formed with high precision.

[0040] After the step of forming the resin electrode, The method may further comprise the step of forming a metal film that covers at least the portion of the metal electrode that is exposed from the resin electrode.

[0041] According to the embodiment, an electronic component having a lower DC resistance can be obtained. [Effects of the Invention]

[0042] According to an electronic component according to one aspect of the present disclosure, it is possible to reduce stress acting on the element body due to bending of the substrate while suppressing an increase in DC resistance. [Brief explanation of the drawings]

[0043] [Figure 1] FIG. 1 is a perspective view showing a first embodiment of a coil component. [Figure 2A] 2 is a cross-sectional view taken along the line XX in FIG. 1. [Figure 2B] FIG. 2 is a cross-sectional view of FIG. 1 taken along the line Y-Y. [Figure 3] FIG. 2 is an exploded plan view of the coil component. [Figure 4] FIG. 10 is a perspective view showing a coil component soldered to a pad provided on a circuit board. [Figure 5] 2 is a cross-sectional view showing a modified example of the coil component according to the first embodiment, corresponding to the YY cross-sectional view of FIG. 1. FIG. [Figure 6]1. FIG. 4 is a cross-sectional view showing another modified example of the coil component according to the first embodiment, corresponding to the YY cross-sectional view of FIG. [Figure 7] 1. FIG. 4 is a cross-sectional view showing yet another modification of the coil component according to the first embodiment, corresponding to the YY cross-sectional view of FIG. [Figure 8] FIG. 10 is a perspective view showing a comparative coil component. [Figure 9] FIG. 10 is a perspective view showing another comparative coil component. [Figure 10] FIG. 10 is a perspective view showing a second embodiment of the coil component. [Figure 11] FIG. 10 is a perspective view showing a third embodiment of the coil component. [Figure 12] FIG. 10 is a perspective view showing a fourth embodiment of the coil component. [Figure 13] FIG. 10 is a perspective view showing a fifth embodiment of a coil component. [Figure 14] FIG. 10 is a perspective view showing a sixth embodiment of a coil component. [Figure 15A] FIG. 13 is a perspective view showing another modified example of the coil component according to the sixth embodiment. [Figure 15B] FIG. 13 is a perspective view showing still another modified example of the coil component according to the sixth embodiment. [Figure 16] FIG. 10 is a perspective view showing a seventh embodiment of a coil component. [Figure 17] FIG. 13 is a perspective view showing an eighth embodiment of the coil component. DETAILED DESCRIPTION OF THE INVENTION

[0044] Hereinafter, an electronic component according to one aspect of the present disclosure will be described in detail with reference to the illustrated embodiments. The drawings include some schematic views, and may not reflect actual dimensions or proportions.

[0045] [First embodiment] <Configuration> FIG. 1 is a perspective view showing a first embodiment of the coil component, with the resin electrodes hatched for convenience. FIG. 2A is an XX cross-sectional view of FIG. 1, which is a LT cross-sectional view of the resin electrode. FIG. 2B is a YY cross-sectional view of FIG. 1, which is a TW cross-sectional view of the resin electrode. FIG. 3 is an exploded plan view of the coil component, showing a view along the T direction from the bottom to the top. For convenience, the external electrodes are omitted from FIG. 3.

[0046] The L direction is the length direction of the coil component 1, the W direction is the width direction of the coil component 1, and the T direction is the height direction of the coil component 1. Hereinafter, the forward direction of the T direction will be referred to as the upper side, and the reverse direction of the T direction will also be referred to as the lower side. The LT cross section shown in FIG. 2A is obtained by cutting the resin electrode along a plane parallel to the plane formed by a line extending in the L direction and a line extending in the T direction. The TW cross section shown in FIG. 2B is obtained by cutting the resin electrode along a plane parallel to the plane formed by a line extending in the T direction and a line extending in the W direction.

[0047] As shown in Figures 1, 2A, 2B and 3, the coil component 1 has a base body 10, a coil 20 provided inside the base body 10, and a first external electrode 30A and a second external electrode 30B provided on the surface of the base body 10 and electrically connected to the coil 20.

[0048] The coil component 1 is electrically connected to wiring on a circuit board (not shown) via the first and second external electrodes 30A and 30B. The coil component 1 is used, for example, as a noise removal filter, and is used in electronic devices such as personal computers, DVD players, digital cameras, TVs, mobile phones, and car electronics.

[0049] The coil 20 has a plurality of coil wirings 22 stacked along the T direction, via wirings 24 extending along the T direction and connecting adjacent coil wirings 22 in the T direction, a first lead conductor 23A connected to the coil wiring 22 in the top layer, and a second lead conductor 23B connected to the coil wiring 22 in the bottom layer.

[0050] Each coil wiring 22 is provided in each of the plurality of magnetic layers 21 except for the topmost magnetic layer 21 and the bottommost magnetic layer 21. Each coil wiring 22 is wound along a plane parallel to the WL plane, arranged side by side in the T direction, and electrically connected in series to form a spiral. Each coil wiring 22 is wound with less than one turn. Via wiring 24 penetrates the magnetic layer 21 in the T direction. Coil wiring 22 adjacent to each other in the T direction are electrically connected in series through the via wiring 24.

[0051] The first lead conductor 23A extends linearly from the end of the coil wiring 22 in the uppermost layer opposite the end to which the via wiring 24 is connected to the first end face 15A of the element body 10. The first lead conductor 23A is exposed at the first end face 15A and is electrically connected to the first external electrode 30A. The second lead conductor 23B extends linearly from the end of the coil wiring 22 in the lowermost layer opposite the end to which the via wiring 24 is connected to the second end face 15B of the element body 10. The second lead conductor 23B is exposed at the second end face 15B and is electrically connected to the second external electrode 30B.

[0052] The coil wiring 22 and the first and second lead conductors 23A, 23B are made of a conductive material such as Ag or Cu. Neither the coil wiring 22 nor the first and second lead conductors 23A, 23B are formed on the magnetic layer 21 arranged on the outermost side in the T direction of the laminate.

[0053] There is no particular limitation on the number of layers of the coil wiring 22. By firing this laminate, a coil 20 that forms a spiral along the T direction is obtained. The number of layers of the magnetic layer 21 arranged at the outermost position in the T direction of the laminate, i.e., the magnetic layer 21 on which neither the coil wiring 22 nor the first and second lead conductors 23A, 23B are formed, is also not particularly limited, and may be two or more layers each.

[0054] The element body 10 is formed in a substantially rectangular parallelepiped shape. The surface of the element body 10 has a first end face 15A, a second end face 15B opposite the first end face 15A, a bottom face 16 perpendicular to the first and second end faces 15A and 15B, a top face 17 opposite the bottom face 16, and a first side face 18A and a second side face 18B located between the first end face 15A and the second end face 15B and other than the bottom face 16 and the top face 17.

[0055] The bottom surface 16 being perpendicular to the first and second end surfaces 15A and 15B means that the angle formed between the bottom surface 16 and the first end surface 15A and the second end surface 15B is 80° or more and 100° or less.

[0056] The first end surface 15A and the second end surface 15B face each other in the L direction. The bottom surface 16 and the top surface 17 face each other in the T direction. The first side surface 18A and the second side surface 18B face each other in the W direction.

[0057] Specifically, the L direction is a direction perpendicular to the first end face 15A and the second end face 15B. Specifically, the W direction is a direction perpendicular to the first side face 18A and the second side face 18B. The W direction is perpendicular to the L direction at the bottom face. The W direction is also perpendicular to the L direction and is parallel to the mounting surface of the coil component 1 (typically, the bottom face 16). Specifically, the T direction is a direction perpendicular to the bottom face 16 and the top face 17. The T direction is perpendicular to the L direction and the W direction.

[0058] The bottom surface 16 is the area visible when the element body 10 is viewed from below. The bottom surface 16 is located between the first end surface 15A and the second end surface 15B and is continuous with both the first end surface 15A and the second end surface 15B. The top surface 17 is the area visible when the element body 10 is viewed from above. In the illustrated example, the bottom surface 16 and the top surface 17 each have curved portions at their ends facing the first and second end surfaces 15A and 15B and the first and second side surfaces 18A and 18B. The first side surface 18A is the area visible when the element body 10 is viewed from the W direction, excluding the bottom surface 16 and the top surface 17. The second side surface 18B is similar to the first side surface 18A. In the illustrated example, the first and second side surfaces 18A and 18B each have curved portions at their ends facing the first and second end surfaces 15A and 15B. The first end face 15A is the area visible when the element body 10 is viewed from the L direction, excluding the bottom face 16, the top face 17, and the two side faces 18A and 18B. The second end face 15B is similar to the first end face 15A.

[0059] The height T of the element body 10 is the distance from the lowest end of the bottom surface 16 to the highest end of the top surface 17 along the T direction.

[0060] At least a first external electrode 30A and a second external electrode 30B are provided on the element body 10. The first external electrode 30A is provided on the first end face 15A side, and the second external electrode 30B is provided on the second end face 15B side.

[0061] The first external electrode 30A includes a metal electrode 31 provided on at least a portion of the bottom surface, and a resin electrode 32 covering a portion of the portion of the metal electrode 31 provided on the bottom surface. The metal electrode 31 is further provided on at least a portion of one of the first end faces 15A. The resin electrode 32 further covers a portion of the portion of the metal electrode 31 provided on at least one of the first end faces 15A. The first external electrode 30A is electrically connected to one end of the coil 20.

[0062] The second external electrode 30B includes a metal electrode 31 provided on at least a portion of the bottom surface, and a resin electrode 32 covering a portion of the portion of the metal electrode 31 provided on the bottom surface. The metal electrode 31 is further provided on at least a portion of one of the second end faces 15B. The resin electrode 32 further covers a portion of the portion of the metal electrode 31 provided on at least one of the second end faces 15B. The second external electrode 30B is electrically connected to the other end of the coil 20.

[0063] The first external electrode 30A and the second external electrode 30B are plane-symmetric with respect to the TW cross section passing through the center of the element body 10, and are point-symmetric with respect to the center of the element body 10.

[0064] The following describes the configuration of the first external electrode 30A. The description of the first external electrode 30A can be applied to the second external electrode 30B by replacing the first end face 15A with the second end face 15B.

[0065] <Configuration of first external electrode> The first external electrode 30A includes a metal electrode 31 that covers the entire surface of the first end face 15A, the bottom face 16, the top face 17, and the ends of the first side face 18A and the second side face 18B on the first end face 15A side, and a resin electrode 32 that covers a portion of the metal electrode 31.

[0066] The metal electrode 31 has a first exposed portion 311, a second exposed portion 312, and a third exposed portion 313. The resin electrode 32 has a first resin electrode 321 and a second resin electrode 322.

[0067] FIG. 4 shows a perspective view of a coil component soldered to a pad provided on a circuit board. As shown in FIG. 4, the coil component 1 is soldered to a pad 6 arranged on a circuit board (not shown) with the bottom surface 16 serving as the mounting surface. For example, a current flows from the circuit board through the first external electrode 30A, the coil 20, and the second external electrode 30B of the coil component 1 in this order. It has been found that the current density is higher on the bottom surface 16 side than on the first end surface 15A side. Therefore, by providing the first, second, and third exposed portions 311, 312, and 313 of the metal electrode 31 exposed from the resin electrode 32 at least on the bottom surface 16, an increase in DC resistance that may arise from the first and second resin electrodes 321 and 322 is more effectively suppressed.

[0068] 4, when the coil component 1 is soldered to a circuit board on the first and second end faces 15A and 15B sides of the bottom surface 16, the flexural stress acts in a direction that causes the element body 10 to bend in the T direction, starting from the first and second end faces 15A and 15B sides of the bottom surface 16. Therefore, by providing the first and second resin electrodes 321 and 322 on the bottom surface 16, the flexural stress can be reduced more effectively.

[0069] That is, by providing the first and second resin electrodes 321, 322 at least on the bottom surface 16 and providing the first, second, and third exposed portions 311, 312, and 313 on the bottom surface 16, it is possible to effectively reduce the bending stress while suppressing the increase in DC resistance caused by providing the first and second resin electrodes 321, 322.

[0070] The first and second resin electrodes 321, 322 can also prevent cracking of the element body 10 due to the difference in thermal expansion between the element body 10 and the metal electrode 31, and cracking of the solder due to the difference in thermal expansion between the solder and the element body 10 after mounting.

[0071] The metal electrode 31 is obtained by firing a conductive paste containing conductive particles such as Ag powder and glass. The metal electrode 31 is also called a base electrode and is directly connected to the coil 20. The metal electrode 31 is usually made of the same material as the coil wiring 22 and the first and second lead conductors 23A and 23B.

[0072] The thickness of the metal electrode 31 is, for example, 1 μm or more and 100 μm or less, and may be 5 μm or more and 80 μm or less. The thickness of the metal electrode 31 is the thickness at approximately the center of the metal electrode 31.

[0073] The approximate center of the metal electrode 31 refers to the center in the W direction of the metal electrode 31 in a TW cross section that bisects the metal electrode 31 provided on the bottom surface 16 or the top surface 17 of the first external electrode 30A in the L direction, or the center in the T direction of the metal electrode 31 in an LT cross section that bisects the metal electrode 31 provided on the first end surface 15A of the first external electrode 30A in the W direction. The thickness of the metal electrode 31 can be measured using an image of the TW cross section or LT cross section exposed by polishing the coil device 1, taken with a scanning electron microscope (SEM).

[0074] The metal electrode 31 in the first external electrode 30A and the metal electrode 31 in the second external electrode 30B may be the same or different in material and thickness.

[0075] The resin electrode 32 contains an organic material and is conductive, and is formed of a resin composition containing conductive particles such as Ag powder and a photosensitive resin, for example.

[0076] The thickness of the resin electrode 32 is, for example, 1 μm or more and 100 μm or less, and may be 5 μm or more and 20 μm or less. The thickness of the resin electrode 32 is the thickness at approximately the center of the resin electrode 32.

[0077] The approximate center of the resin electrode 32 refers to the center in the W direction of any one of the resin electrodes 32 provided on the bottom surface 16 or the top surface 17 of the first external electrode 30A in a TW cross section that bisects the resin electrode 32 in the L direction, or the center in the T direction of any one of the resin electrodes 32 provided on the first end surface 15A of the first external electrode 30A in an LT cross section that bisects the resin electrode 32 in the W direction. The thickness of the resin electrode 32 can be measured using an SEM image of the TW cross section or LT cross section exposed by polishing the coil device 1.

[0078] The resin electrodes 32 have a uniform thickness. In particular, if the resin electrodes 32 provided on the bottom surface 16 have a uniform thickness, rattle and tilt of the coil component 1 are suppressed when the coil component 1 is mounted on the bottom surface 16.

[0079] The term "uniform thickness" means that the thickness of an end of any one resin electrode 32 on any plane is within ±20% of the thickness at the approximate center of the resin electrode 32. The end of the resin electrode 32 is one of three points that divide the resin electrode 32 into four equal parts in the W direction on the above-mentioned TW cross section used to determine the approximate center of the resin electrode 32, excluding the middle (corresponding to the approximate center of the resin electrode 32), or one of three points that divide the resin electrode 32 into four equal parts in the T direction on the above-mentioned LT cross section used to determine the approximate center of the resin electrode 32, excluding the middle (corresponding to the approximate center of the resin electrode 32).

[0080] When multiple resin electrodes 32 are provided on the same surface, the materials and thicknesses of the multiple resin electrodes 32 may be the same or different. In this embodiment, the thicknesses of the first resin electrode 321 and the second resin electrode 322 are the same on any surface and are the same on all surfaces.

[0081] The thickness of the plurality of resin electrodes 32 on any surface is the same means that the thickness of any one resin electrode 32 on that surface is within ±20% of the average thickness of the plurality of resin electrodes 32 on that surface.

[0082] The coil device 1 may include a plating layer 40 on the bottom surface 16 that covers at least a portion of the first external electrode 30A. The plating layer 40 is not directly connected to the coil 20, but is electrically connected to the first external electrode 30A via the first, second, and third exposed portions 311, 312, and 313 and / or the first and second resin electrodes 321 and 322. The plating layer 40 is typically formed of a material different from that of the coil wiring 22 and the first and second lead conductors 23A and 23B. The plating layer 40 is a thin metal film formed by surface treatment (typically, a wet plating method).

[0083] The metal contained in the plating layer 40 is, for example, nickel and tin. The plating layer 40 may be a single layer, or may be two or more layers. The plating layer 40 may have a laminated structure of a nickel plating layer and a tin plating layer. The thickness of each plating layer 40 is not particularly limited and is, for example, 2 μm or more and 15 μm or less.

[0084] In FIG. 2A, the plating layer 40 is indicated by a two-dot chain line. In FIG. 2A, the plating layer 40 covers the entire first external electrode 30A and is electrically connected to the first external electrode 30A. Therefore, the plating layer 40 causes current that tends to concentrate on the bottom surface 16 to also flow to the first end surface 15A, for example, via a solder fillet, to the circuit board. This reduces the effect of an increase in DC resistance due to the provision of the first and second resin electrodes 321, 322. The plating layer 40 may cover only a portion of the first external electrode 30A.

[0085] <Detailed configuration of the first external electrode> The resin electrode 32 and the metal electrode 31 of the first external electrode 30A will be described in detail below. The resin electrode 32 has two strip-shaped first and second resin electrodes 321 and 322. The strip-shaped first and second resin electrodes 321 and 322 extend continuously in the L direction on the bottom surface 16, the T direction on the first end surface 15A, and the L direction on the top surface 17, in this order. The first resin electrode 321 and the second resin electrode 322 are arranged side by side in the W direction with a gap between them.

[0086] The metal electrode 31 has first, second, and third exposed portions 311, 312, and 313 exposed from the resin electrode 32. The first exposed portion 311 is located at an end of the first side surface 18A on the first end surface 15A side, an end of the bottom surface 16 on the first end surface 15A side and on the first side surface 18A side, an end of the top surface 17 on the first end surface 15A side and on the first side surface 18A side, and an end of the first end surface 15A on the first side surface 18A side. The second exposed portion 312 is located between the first resin electrode 321 and the second resin electrode 322, and is a strip-like portion that extends continuously in the L direction at the bottom surface 16, the T direction at the first end surface 15A, and the L direction at the top surface 17, in this order. The third exposed portion 313 is located at the end of the second side surface 18B on the first end surface 15A side, the end of the bottom surface 16 on the first end surface 15A side and the second side surface 18B side, the end of the top surface 17 on the first end surface 15A side and the second side surface 18B side, and the end of the first end surface 15A on the second side surface 18B side.

[0087] The first exposed portion 311, the first resin electrode 321, the second exposed portion 312, the second resin electrode 322 and the third exposed portion 313 are arranged in line in this order in the W direction from the first side surface 18A side, so that the resin electrodes and the exposed portions alternate.

[0088] The first and second resin electrodes 321, 322 are provided in a strip shape from the bottom surface 16 to the top surface 17, which further increases the effect of reducing flexural stress. Furthermore, the second exposed portion 312 is provided between the first resin electrode 321 and the second resin electrode 322, which further reduces the increase in DC resistance. In addition, the first exposed portion 311 and the third exposed portion 313 are provided on the first and second side surfaces 18A, 18B of the element body 10, respectively, which further reduces the increase in DC resistance.

[0089] Since the first and second resin electrodes 321, 322 are also provided on the first end surface 15A, cracking of the solder is also more easily suppressed when the coil component 1 is mounted using the bottom surface 16 as the mounting surface, as shown in Fig. 4. The fillet of the solder 5 is usually formed so as to cover at least a portion of the first external electrode 30A on the first end surface 15A. The first and second resin electrodes 321, 322 can suppress cracking of the solder 5 due to the difference in thermal expansion between the solder 5 and the element body 10.

[0090] The first resin electrode 321 and the second resin electrode 322 are provided symmetrically with respect to the LT cross section passing through the center of the element body 10. This makes it easier to suppress rattle and tilt of the coil component 1 when it is mounted.

[0091] The first, second, and third exposed portions 311, 312, and 313 each include a first metal portion 3101 provided on the bottom surface 16, a second metal portion 3102 provided on the first end surface 15A, and a third metal portion 3103 provided on the top surface 17. The first and third exposed portions 311 and 313 are also provided on the first end surface 15A sides of the first and second side surfaces 18A and 18B, respectively. The first and second resin electrodes 321 and 322 each include a first resin portion 3201 provided on the bottom surface 16, a second resin portion 3202 provided on the first end surface 15A, and a third resin portion 3203 provided on the top surface 17. In the first external electrode 30A in FIG. 2A, the boundary between the first resin portion 3201 and the second resin portion 3202, and the boundary between the second resin portion 3202 and the third resin portion 3203 are indicated by dashed lines.

[0092] (First metal part and first resin part) The first metal portion 3101 and the first resin portion 3201 will be described below. Three first metal portions 3101 are provided. The three first metal portions 3101 are part of the first, second, and third exposed portions 311, 312, and 313, respectively. Two first resin portions 3201 are provided. The two first resin portions 3201 are part of the first and second resin electrodes 321 and 322, respectively. On the bottom surface 16, the first metal portions 3101 and the first resin portions 3201 are arranged alternately in the W direction. Two of the first metal portions 3101 are provided at both ends of the bottom surface 16 in the W direction.

[0093] The first metal portion 3101 and the first resin portion 3201 are alternately arranged in the W direction when the boundary line BL between the first metal portion 3101 and the first resin portion 3201 is B In other words, the boundary line BL is along the L direction. B is along the L direction, the boundary line BL B The acute angle θ between the boundary line BL and the L direction is between 0° and 30°. B On the bottom surface 16, when the boundary line between the first metal portion 3101 and the first resin portion 3201 is curved or meandering, the line connecting both ends of the boundary line is referred to as the boundary line BL B In FIG. 1, for convenience, the boundary line BL on the top surface 17 is B The boundary line BL on the bottom surface 16 is shown. B Also, the boundary line BL on the top surface 17 in Figure 1 B It is shown similarly to

[0094] The two first resin portions 3201 are provided symmetrically with respect to a line that passes through the center of the bottom surface 16 and extends in the L direction. This suppresses rattles and tilts of the coil component 1 mounted on the bottom surface 16.

[0095] In the first external electrode 30A, the total coverage of the first resin portions 3201 is approximately 50%. The coverage of the first resin portions 3201 is not particularly limited and may be set appropriately taking into consideration the balance between the effect of suppressing an increase in resistance and the effect of reducing deflection stress. The coverage of the first resin portions 3201 may be 30% or more and 70% or less. When the coverage of the first resin portions 3201 is 50% or more, the effect of reducing deflection stress can be particularly improved. The coverage of the first resin portions 3201 is calculated by dividing the total area of ​​the first resin portions 3201 in the first external electrode 30A by the total area of ​​all the first resin portions 3201 and all the first metal portions 3101.

[0096] The maximum width Wb of the first resin portion 3201 in the W direction is greater than the maximum width Wa1 of the first metal portion 3101 adjacent to the first resin portion 3201 in the W direction. This further reduces the deflection stress. In the coil device 1, the ratio Wb / Wa1 of the maximum width Wb of the first resin portion 3201 to the maximum width Wa1 of the first metal portion 3101 is approximately 1.7. The Wb / Wa1 may be greater than 1 and equal to or less than 5, or may be equal to or greater than 1.2 and equal to or less than 4.5.

[0097] The maximum width Wa1 is the maximum of the lengths in the W direction of the first metal portions 3101 adjacent to the first resin portion 3201 in the projection of the bottom surface 16. When there are two first metal portions 3101 adjacent to the first resin portion 3201, the maximum width Wa of each first metal portion 3101 is calculated, and the larger of the two is taken as Wa1.

[0098] The maximum width Wb is the maximum length of the first resin portion 3201 in the W direction in a projection of the bottom surface 16.

[0099] The maximum width Wa2 of the first metal portion 3101 sandwiched between two adjacent first resin portions 3201 is approximately 110 μm. This makes it possible to easily adjust the coverage of the first resin portions 3201. The maximum width Wa2 may be 10 μm or more and 160 μm or less, or may be 10 μm or more and 120 μm or less.

[0100] The maximum width Wa2 is the maximum length in the W direction of the first metal portion 3101 sandwiched between two adjacent first resin portions 3201 in a projection of the bottom surface 16. When there are two first metal portions 3101 sandwiched between two adjacent first resin portions 3201, the maximum width Wa of each first metal portion 3101 is calculated, and the larger of the two is designated as Wa2. The maximum widths Wa1 and Wa2 may be the same.

[0101] (Second metal part and second resin part) Next, the second metal portion 3102 and the second resin portion 3202 will be described. Three second metal portions 3102 are provided. The three second metal portions 3102 are part of the first, second, and third exposed portions 311, 312, and 313, respectively. Two second resin portions 3202 are provided. The two second resin portions 3202 are part of the first and second resin electrodes 321 and 322, respectively. On the first end surface 15A, the second metal portions 3102 and the second resin portions 3202 are arranged alternately in the W direction. Two of the second metal portions 3102 are provided at each end of the first end surface 15A in the W direction.

[0102] The second metal portion 3102 and the second resin portion 3202 are alternately arranged in the W direction when the boundary line BL between the second metal portion 3102 and the second resin portion 3202 is t In other words, the boundary line BL is along the T direction. t is along the T direction, the boundary line BL t The acute angle θ between the boundary line BL and the T direction is between 0° and 30°. t In the first end surface 15A, when the boundary line between the first metal portion 3101 and the first resin portion 3201 is curved or meandering, the line connecting both ends of the boundary line is referred to as the boundary line BL t Let's say.

[0103] Both of the two second resin portions 3202 are provided across from the bottom surface 16 side of the first end surface 15A to the top surface 17 side. Each of the second resin portions 3202 may be provided in a region from the bottom surface 16 side of the first end surface 15A to 1 / 2 of the height of the element body 10. Each of the second resin portions 3202 may be provided in a region from the bottom surface 16 side of the first end surface 15A to 1 / 3 of the height of the element body 10. Each of the second resin portions 3202 may be provided in a region from the bottom surface 16 side of the first end surface 15A to 1 / 6 of the height of the element body 10.

[0104] In the first external electrode 30A, the total coverage of the second resin portion 3202 is approximately 50%. The coverage of the second resin portion 3202 is not particularly limited and may be set appropriately taking into consideration the balance between the effect of suppressing an increase in resistance and the effect of reducing deflection stress. The coverage of the second resin portion 3202 may be 30% or more and 70% or less. When the coverage of the second resin portion 3202 is 50% or more, the effect of reducing deflection stress can be particularly improved. The coverage of the second resin portion 3202 is calculated in the same way as the first resin portion 3201.

[0105] The maximum width Wb of the second resin portion 3202 in the W direction is wider than the maximum width Wa1 of the second metal portion 3102 adjacent to the second resin portion 3202 in the W direction. This further reduces the deflection stress. In the coil device 1, the ratio Wb / Wa1 of the maximum width Wb of the second metal portion 3102 to the maximum width Wa1 of the second metal portion 3102 is approximately 1.7. The Wb / Wa1 may be greater than 1 and less than or equal to 5, or may be greater than or equal to 1.2 and less than or equal to 4.5. The maximum width Wa1 of the second metal portion 3102 is calculated in the same manner as for the first metal portion 3101. The maximum width Wb of the second resin portion 3202 is calculated in the same manner as for the first resin portion 3201.

[0106] The second metal portion 3102 sandwiched between two adjacent second resin portions 3202 has a maximum width Wa2 of approximately 110 μm. The maximum width Wa2 may be 10 μm or more and 160 μm or less, or 10 μm or more and 120 μm or less. The maximum width Wa2 of the second metal portion 3102 is calculated in the same manner as the first metal portion 3101. The maximum widths Wa1, Wa2, and Wb at the first end surface 15A are shown in the same manner as the maximum widths Wa1, Wa2, and Wb at the bottom surface 16 in FIG. 2B.

[0107] The two second resin portions 3202 are arranged line-symmetrically with respect to a line that passes through the center of the first end surface 15A and extends in the T direction. The arrangement of the two second resin portions 3202 is also point-symmetric with respect to the center of the first end surface 15A.

[0108] (Third metal part and third resin part) Next, the third metal portion 3103 and the third resin portion 3203 will be described. Three third metal portions 3103 are provided. The three third metal portions 3103 are part of the first, second, and third exposed portions 311, 312, and 313, respectively. Two third resin portions 3203 are provided. The two third resin portions 3203 are part of the first and second resin electrodes 321 and 322, respectively. On the top surface 17, the third metal portions 3103 and the third resin portions 3203 are arranged alternately in the W direction. Two of the third metal portions 3103 are provided at each end of the top surface 17 in the W direction.

[0109] The shape, arrangement, coverage, size, etc. of the third resin portion 3203 on the top surface 17 are the same as those of the first resin portion 3201 on the bottom surface 16.

[0110] 5 shows a modified example of the coil device, which is cut along a plane corresponding to the YY cross section of FIG. 5, the first and second resin electrodes 321, 322 protrude outward in the T direction from the surface of the metal electrode 31 on which they are provided. It is desirable that the first and second resin electrodes 321, 322 form unevenness, particularly on the bottom surface 16. This allows solder to penetrate so as to reduce the step between the first and second resin electrodes 321, 322 and the metal electrode 31 during mounting, thereby improving the connection strength between the circuit board and the coil component 1. In addition, the plating layer 40 covering the first external electrode 30A is less likely to peel off.

[0111] Another modified example is shown in Fig. 6. Fig. 6 is a view of a coil device according to another modified example, cut along a plane corresponding to the YY cross section in Fig. 1. When the first and second resin electrodes 321, 322 protrude outward in the T direction beyond the surface of the metal electrode 31 on which the resin electrodes are provided, a metal film 41 may be provided so as to cover the first, second, and third exposed portions 311, 312, and 313, as shown in Fig. 6. The metal film 41 is made of a metal material such as Ag. This makes it possible to reduce the DC resistance increased by the resin electrodes 32 without changing the size of the coil component 1.

[0112] The metal film 41 does not contain organic matter and is conductive. The metal film 41 is not directly connected to the coil 20. The metal film 41 is electrically connected to the coil 20 via the first, second, and third exposed portions 311, 312, and 313, and serves as an electrode. Hereinafter, the metal electrode 31, the resin electrode 32, and the metal film 41 may be collectively referred to as the first external electrode 30A. The metal film 41 is typically formed from the same material as the coil wiring 22, the first and second lead conductors 23A and 23B, and the metal electrode 30. The metal film 41 is typically formed by a method different from that of the plating layer 40 (for example, a method similar to that for the metal electrodes or a dry plating method).

[0113] The metal film 41 may further cover the first and second resin electrodes 321, 322. In this case, the metal film 41 can be electrically connected to the first external electrode 30A via the first and second resin electrodes 321, 322.

[0114] The metal film 41 may be disposed so as to fill in the steps between the first and second resin electrodes 321, 322 and the first, second, and third exposed portions 311, 312, and 313, so that the surfaces of the first and second resin electrodes 321, 322 and the surface of the metal film 41 at least on the bottom surface 16 are flush with each other. This reduces rattle and tilt of the coil component 1 during mounting.

[0115] Whether the surfaces of the first and second resin electrodes 321, 322 on the bottom surface 16 are flush with the surface of the metal film 41 can be confirmed by taking enlarged photographs of multiple (e.g., 3 to 8) different TW cross sections obtained by polishing the coil component 1. The multiple TW cross sections can be obtained in the process of polishing the coil component 1 in the L direction. In the enlarged photographs, the maximum difference between the distance from the surface of the bottom surface 16 to the surfaces of the first and second resin electrodes 321, 322 and the distance from the surface of the bottom surface 16 to the surface of the metal film 41 is calculated. The maximum value is calculated for each enlarged photograph, and an average value is calculated. If this average value is 5 μm or less, it can be said that the surfaces of the first and second resin electrodes 321, 322 on the bottom surface 16 are flush with the surface of the metal film 41. The magnification of the enlarged photographs is, for example, 50 times or more and 300 times or less.

[0116] The metal electrode 31 may be formed in an uneven shape, and the first and second resin electrodes 321, 322 may be provided in the recesses of the metal electrode 31, so that the surfaces of the first, second, and third exposed portions 311, 312, 313 and the surfaces of the first and second resin electrodes 321, 322 are flush with each other.

[0117] The surface of the plating layer 40 may be made smooth by partially thickening the plating layer 40 to fill in the steps between the first and second resin electrodes 321 and 322 and the first, second and third exposed portions 311, 312 and 313.

[0118] 7 shows yet another modified example of the coil device, which is cut along a plane corresponding to the YY cross section of FIG. 7, in the T-W cross section, the length (width) in the W direction of the first surface X of the first and second resin electrodes 321, 322 on the metal electrode 31 side may be narrower than the width of the second surface Y of the resin electrode on the opposite side from the first surface X. In other words, the width of the first and second resin electrodes 321, 322 in the T-W cross section may narrow in a stepped or linear manner toward the metal electrode 31. This prevents the plating layer 40 from peeling from the contact area between the metal electrode 31 and the first and second resin electrodes 321, 322. In particular, when the first and second resin electrodes 321, 322 have the above-described cross-sectional shape on the bottom surface 16, an anchor effect is produced, improving the solder joint strength between the circuit board and the coil component 1.

[0119] In the T-W cross section, the acute angle (hereinafter referred to as the taper angle θ) formed between at least one side surface of the first and second resin electrodes 321, 322 and the metal electrode 31 is, for example, not less than 60° and less than 90°. The taper angle θ can also be measured using an SEM image of the T-W cross section in the same manner as above.

[0120] ≪Manufacturing method≫ The coil device 1 is manufactured by a method including the steps of preparing an element body 10 having a first end face 15A, a second end face 15B opposing the first end face 15A, and a bottom face 16 perpendicular to the first end face 15A and the second end face 15B, forming a metal electrode 31 on at least a portion of the bottom face 16, and forming a resin electrode 32 that covers a portion of the portion of the metal electrode 31 provided on the bottom face 16. In the step of forming the resin electrode, first, second, and third exposed portions 311, 312, and 313 of the metal electrode 31 that are exposed from the resin electrode 32 are formed on the bottom face 16.

[0121] <Preparing the body> In this embodiment, an element body 10 and a coil 20 provided inside the element body 10 are prepared. First, multiple magnetic layers 21 each having coil wiring 22 formed thereon are laminated so as to be sandwiched between two or more magnetic layers 21 each having no coil wiring 22 formed thereon. A magnetic layer 21 having a first lead conductor 23A or a second lead conductor 23B is disposed on the outermost of each of the multiple magnetic layers 21 each having coil wiring 22 formed thereon. Next, this laminate is fired. In this manner, the element body 10 and the coil 20 disposed inside the element body 10 are obtained. The firing temperature is not particularly limited and may be set appropriately taking into consideration the type of material used, etc. The configuration of the coil 20 and element body 10 is as shown in FIG. 2A.

[0122] The magnetic layer 21 is obtained by forming a paste containing a magnetic material into a sheet. Examples of magnetic materials include Ni-Cu-Zn ferrite materials. Ni-Cu-Zn ferrite materials contain, for example, 40 mol % to 49.5 mol % of Fe calculated as Fe2O3, 2 mol % to 35 mol % of Zn calculated as ZnO, 6 mol % to 13 mol % of Cu calculated as CuO, and 10 mol % to 45 mol % of Ni calculated as NiO. The magnetic material may contain additives and unavoidable impurities as needed. Examples of additives include Mn3O4, Co3O4, SnO2, Bi2O3, and SiO2.

[0123] Specifically, the magnetic layer 21 is fabricated as follows. First, Fe2O3, ZnO, CuO, and NiO are weighed out to obtain a predetermined composition. These and pure water are placed in a ball mill along with PSZ (partially stabilized zirconia) media and wet-mixed and pulverized for 4 to 8 hours. The water is then evaporated to dryness, and the mixture is calcined at a temperature of 700°C to 800°C for 2 to 5 hours. This yields a Ni-Cu-Zn ferrite material (magnetic material).

[0124] The resulting magnetic material, an organic binder such as polyvinyl butyral, an organic solvent such as ethanol or toluene, and a plasticizer are placed in a ball mill along with PSZ media and further mixed. The resulting mixture is then formed into a sheet with a thickness of 5 μm or more and 30 μm or less using a doctor blade method or the like. The sheet is then punched into a predetermined shape (typically rectangular) to obtain the magnetic layer 21.

[0125] In the magnetic layer 21 thus fabricated, via holes are formed at predetermined locations by, for example, laser irradiation.

[0126] A conductive paste containing a conductive material (typically Ag powder) as a main component is prepared separately. The conductive paste may contain a solvent, a resin, a dispersant, and the like in addition to the conductive material. This conductive paste is applied to the magnetic layer 21, in which the via holes have been formed, by, for example, screen printing. As a result, the via holes are filled with the conductive paste, and the coil wiring 22 and the first and second lead conductors 23A and 23B are formed in the magnetic layer 21.

[0127] Next, the multiple magnetic layers 21 thus produced are stacked in a predetermined order and thermocompressed to produce a laminated block. The laminated block is then cut into individual pieces using a dicer or the like. These individual pieces are sintered in a sintering furnace at 900°C to 920°C for 2 to 4 hours. The resulting sintered body is placed in a rotary barrel machine along with media and rotated to polish the ridges and corners of the sintered body. This produces the element body 10 and coil 20.

[0128] <Formation of the first and second external electrodes> Next, a first external electrode 30A is provided on the first end face 15A side of the element body 10, and a second external electrode 30B is provided on the second end face 15B side. The step of providing the first external electrode 30A includes the steps of forming a metal electrode 31 on at least a portion of the bottom face 16 on the first end face 15A side, and forming a resin electrode 32 that covers a portion of the portion of the metal electrode 31 provided on the bottom face 16. In the step of forming the resin electrode 32, first, second, and third exposed portions 311, 312, and 313 of the metal electrode 31 that are exposed from the resin electrode 32 are formed. The second external electrode 30B is provided in the same manner as the first external electrode 30A.

[0129] <Formation of metal electrodes> The metal electrodes 31 are formed in two locations on the first end face 15A side and the second end face 15B side of the element body 10. The metal electrodes 31 on the first end face 15A side are provided on the entire surface of the first end face 15A and on each end of the bottom face 16, top face 17, first side face 18A, and second side face 18B on the first end face 15A side. The metal electrodes 31 on the second end face 15B side are provided on the entire surface of the second end face 15B and on each end of the bottom face 16, top face 17, first side face 18A, and second side face 18B on the second end face 15B side. Each metal electrode 31 is directly connected to the coil 20.

[0130] The metal electrodes 31 are formed, for example, by applying a conductive paste containing conductive particles such as Ag powder and glass to predetermined locations on the element body 10 and firing the paste at 750°C to 850°C. The application method is not particularly limited and may be, for example, a dipping method or a screen printing method. The firing sinters the conductive particles to form a metal layer. The firing temperature is not particularly limited and may be set appropriately taking into account the type of material used, etc.

[0131] <Formation of resin electrodes> Next, a resin electrode 32 is formed to cover a portion of the metal electrode 31. The resin electrode 32 is formed, for example, by the steps of applying a conductive composition containing a photosensitive resin to at least a portion of the metal electrode 31 formed on the bottom surface 16, irradiating a portion of the applied resin composition with laser light, and removing the portion or the remainder of the resin composition after the irradiation step. As a result, first, second, and third exposed portions 311, 312, and 313 of the metal electrode 31 exposed from the resin electrode 32 are formed on the bottom surface 16, and the first and second external electrodes 30A and 30B according to this embodiment are obtained.

[0132] The photosensitive resin may be a positive type that is decomposed by laser light, or a negative type that is polymerized or crosslinked by laser light. When a positive type photosensitive resin is used, the portion exposed to the laser light is removed in the removal process. When a negative type photosensitive resin is used, the portion not exposed to the laser light is removed in the removal process. A mask may be used during irradiation with laser light. The mask partially blocks the laser light.

[0133] By employing photolithography using laser light, resin electrodes 32 of desired shapes and thicknesses can be formed with higher precision than by screen printing. For example, the maximum width Wa of the second exposed portion 312 sandwiched between the first resin electrode 321 and the second resin electrode 322 can be set to 10 μm or more and 160 μm or less. Alternatively, the maximum width Wb of the first resin electrode 321 and the second resin electrode 322 can be set to 10 μm or more and 160 μm or less. Furthermore, the thickness of the resin electrode 32 can be made uniform. With screen printing, it is generally difficult to achieve a maximum width Wa or Wb of 80 μm or less due to the influence of the elongation of the screen plate and the viscosity of the resin composition.

[0134] Photolithography using laser light allows the degree of polymerization or cross-linking of the photosensitive resin to be controlled as desired. Therefore, as shown in FIG. 7 , the width of the first surface X of the first and second resin electrodes 321, 322 on the metal electrode 31 side can be made narrower than the width of the second surface Y of the resin electrode opposite the first surface X. For example, when a negative photosensitive resin is used, the width of the first and second resin electrodes 321, 322 in the T-W cross section can be narrowed stepwise or linearly toward the metal electrode 31 by reducing the intensity of laser light irradiation or the number of irradiations to reduce the degree of polymerization or cross-linking of the photosensitive resin.

[0135] The conductive resin composition may further contain conductive particles, such as Ag powder, and may further contain a solvent and a dispersant.

[0136] Specifically, the resin composition contains 60% to 85% by mass of Ag powder, 2% to 20% by mass of an epoxy resin (e.g., bisphenol A-type epoxy resin), and 10% to 20% by mass of an organic solvent (e.g., diethylene glycol monobutyl ether). The resin composition may further contain 1% by mass or less of a thermosetting resin (e.g., phenolic resin), a silane coupling agent (e.g., 3-glycidoxypropyltrimethoxysilane), and a curing agent (e.g., an imidazole compound). A paste obtained by mixing 100% by mass of the resin composition with 10% by mass of a photosensitive varnish may be used for application.

[0137] When a negative epoxy resin is used as the photosensitive resin, the portion where the resin electrode 32 is to be formed is irradiated with laser light. The portion coated with the resin composition is then immersed in a developer. The epoxy resin not irradiated with the laser light is dissolved in the developer and removed. On the other hand, the exposed epoxy resin hardens and remains. Finally, the resin electrode 32 is formed by heat treatment at 230°C for approximately 1 hour.

[0138] <Metal film formation> After the metal electrode 31 is formed, a step of forming the metal film 41 may be carried out before or after the resin electrode 32 is formed.

[0139] The metal film 41 can be formed, for example, by the same method and material as the metal electrode 31, before forming the resin electrode 32. Specifically, the metal film 41 is formed by applying a conductive paste containing a conductive material (typically, Ag powder) as a main component to at least portions corresponding to the first, second, and third exposed portions 311, 312, and 313 of the metal electrode 31, and firing the paste at 750° C. or higher and 850° C. or lower, before forming the resin electrode 32. The firing for forming the metal electrode 31 and the firing for forming the metal film 41 may be performed simultaneously.

[0140] The metal film 41 can be formed by, for example, a sputtering method after forming the resin electrode 32. Specifically, the metal film 41 is formed on at least the first, second, and third exposed portions 311, 312, and 313 of the metal electrode 31 by sputtering using Ag as a target.

[0141] <Formation of plating layer> After the step of forming the resin electrode 32 and, optionally, the step of forming the metal film 41, a step of forming a plating layer 40 that covers at least a portion of the first and second external electrodes 30A, 30B may be carried out. The plating layer 40 is typically formed by a wet plating method. There are no particular limitations on the wet plating method, and it may be an electrolytic plating method or an electroless plating method. The step of forming the plating layer 40 is carried out multiple times as necessary. The plating layer is formed, for example, by an electrolytic plating method, in which a Ni plating layer and a Sn plating layer are formed in this order.

[0142] <Evaluation> The coil component 1 according to this embodiment was evaluated by simulation. The size, number, and arrangement of the resin electrodes 32 of the coil component 1 are as shown in FIG. 1 . The coil component 1 used in the simulation further includes a metal film 41 covering the first, second, and third exposed portions 311, 312, and 313. The coil component 1 measures a length (L) of 1.6 mm, a width (W) of 0.8 mm, and a height (T) of 0.8 mm. As shown in FIG. 4 , the coil component 1 was assumed to be mounted on a bottom surface 16 of the coil component 1, with first and second end surfaces 15A and 15B of the bottom surface 16 soldered to pads 6 located near the center of a substrate (thickness 1.6 mm) (not shown). Femtet (registered trademark) manufactured by Murata Software Co., Ltd. was used for the simulation.

[0143] <Deflection stress> For the evaluation of deflection stress, the composition and physical properties of each component were set as shown in Table 1. The deflection test was carried out as follows: The board was supported from below at two points (support distance 90 mm) so that the side on which coil component 1 was mounted faced downward. A load was applied from above to below with a pressure tool at approximately the center of the board at a speed of 0.08 mm / sec. The stress acting on coil component 1 when the board deflected 5 mm was obtained as the deflection stress.

[0144] [Table 1]

[0145] <Resistance value> For the evaluation of the resistance value, the composition and physical properties of each member were set as shown in Table 2. The DC resistance value between the first and second end faces 15A and 15B of the coil component 1 and the surface of the pad 6 was obtained as the resistance value.

[0146] [Table 2]

[0147] Coil components 2A and 2B were prepared for comparison. Comparative coil component 2A has an element body and metal electrodes with the same configuration as coil component 1, except that it does not have resin electrodes 32 and has a metal film 41 covering the entire surface of metal electrode 31. Comparative coil component 2B has an element body and metal electrodes with the same configuration as coil component 1, except that it has a metal film 41 covering the entire surface of metal electrode 31 and a resin electrode 32 covering the entire surface of metal film 41. FIG. 8 is a perspective view showing comparative coil component 2A. FIG. 9 is a perspective view showing comparative coil component 2B.

[0148] The comparative coil component 2B has a resin electrode 32 that covers the entire surface of the metal film 41, and therefore its deflection stress is reduced by 73.6% compared to the comparative coil component 2A. On the other hand, the resistance value of the comparative coil component 2B is increased by 66.6%.

[0149] In contrast, the coil component 1 according to this embodiment has the first, second, and third exposed portions 311, 312, and 313 at least on the bottom surface 16, and therefore the resistance increase rate is limited to 21.4%. Meanwhile, the first and second strip-shaped resin electrodes 321 and 322 reduce the deflection stress by as much as 53.5%. In this way, the coil component according to this embodiment can effectively reduce the deflection stress while suppressing an increase in resistance.

[0150] [Second embodiment] FIG. 10 is a perspective view showing a second embodiment of a coil component, corresponding to FIG. 1 of the first embodiment. The second embodiment differs from the first embodiment in the size, number, and arrangement of the resin electrodes. This different configuration will be described below. The configuration of the second embodiment is the same as that of the first embodiment except for the size, number, and arrangement of the resin electrodes, so a description thereof will be omitted. In the second embodiment, the same reference numerals as those in the first embodiment represent the same configuration as in the first embodiment, so a description thereof will be omitted. In the second embodiment, the manufacturing method is the same as that in the first embodiment, so a description thereof will be omitted.

[0151] The configuration of the first external electrode 30A of the coil component 1A of the second embodiment will be described below. The second external electrode 30B has a similar configuration. The resin electrode 32 is in the shape of a single strip and extends continuously in the L direction on the bottom surface 16, in the T direction on the first end surface 15A, and in the L direction on the top surface 17, in this order.

[0152] The metal electrode 31 has first and second exposed portions 311, 312 exposed from the resin electrode 32. The first exposed portion 311 is located at an end of the first side surface 18A on the first end face 15A side, an end of the bottom surface 16 on the first end face 15A side and on the first side face 18A side, an end of the top surface 17 on the first end face 15A side and on the first side face 18A side, and an end of the first end surface 15A on the first side face 18A side. The second exposed portion 312 is located at an end of the second side surface 18B on the first end face 15A side, an end of the bottom surface 16 on the first end face 15A side and on the second side face 18B side, an end of the top surface 17 on the first end face 15A side and on the second side face 18B side, and an end of the first end surface 15A on the second side face 18B side.

[0153] The first exposed portion 311, the resin electrode 32, and the second exposed portion 312 are arranged side by side in the W direction in this order from the first side surface 18A side. The first and second exposed portions 311, 312 are provided on the first and second side surfaces 18A, 18B sides of the element body 10, respectively.

[0154] The coverage of the resin electrode 32 on the bottom surface 16, the top surface 17, and the first end surface 15A is approximately 40%. On each of the above surfaces, the ratio of the maximum width Wb to the maximum width Wa1: Wb / Wa1 is greater than 1. Specifically, the ratio Wb / Wa1 is approximately 1.4.

[0155] <Evaluation> Coil device 1A was evaluated by simulation in the same manner as in Embodiment 1. Coil device 1A has an element body and metal electrodes with the same configuration as coil device 1, except that one strip-shaped resin electrode 32 is provided approximately in the center of first external electrode 30A in the W direction, and coil device 1A has metal film 41 covering first and second exposed portions 311, 312.

[0156] The coil device 1A according to this embodiment has the first and second exposed portions 311, 312 at least on the bottom surface 16, and therefore the resistance increase rate is only 15.6% compared to the comparative coil device 2A. On the other hand, the band-shaped resin electrode 32 reduces the deflection stress of the coil device 1A by as much as 34.6%.

[0157] [Third embodiment] FIG. 11 is a perspective view showing a coil component according to a third embodiment, corresponding to FIG. 1 of the first embodiment. The third embodiment differs from the first embodiment in the size, number, and arrangement of the resin electrodes. This difference in configuration will be described below. The configuration of the third embodiment is the same as that of the first embodiment except for the size, number, and arrangement of the resin electrodes, and therefore a description thereof will be omitted. In the third embodiment, the same reference numerals as those in the first embodiment represent the same configuration as in the first embodiment, and therefore a description thereof will be omitted. In the third embodiment, the manufacturing method is the same as that of the first embodiment, and therefore a description thereof will be omitted.

[0158] The configuration of the first external electrode 30A of the coil component 1B of the third embodiment will be described below. The second external electrode 30B has a similar configuration. The resin electrode 32 is in the shape of a single strip and extends continuously in the L direction on the bottom surface 16, in the T direction on the first end surface 15A, and in the L direction on the top surface 17, in this order.

[0159] The metal electrode 31 has first and second exposed portions 311, 312 exposed from the resin electrode 32. The first exposed portion 311 is located at an end of the first side surface 18A on the first end face 15A side, an end of the bottom surface 16 on the first end face 15A side and on the first side face 18A side, an end of the top surface 17 on the first end face 15A side and on the first side face 18A side, and an end of the first end surface 15A on the first side face 18A side. The second exposed portion 312 is located at an end of the second side surface 18B on the first end face 15A side, an end of the bottom surface 16 on the first end face 15A side and on the second side face 18B side, an end of the top surface 17 on the first end face 15A side and on the second side face 18B side, and an end of the first end surface 15A on the second side face 18B side.

[0160] The first exposed portion 311, the resin electrode 32, and the second exposed portion 312 are arranged side by side in the W direction in this order from the first side surface 18A side. The first and second exposed portions 311, 312 are provided on the first and second side surfaces 18A, 18B sides of the element body 10, respectively.

[0161] The coverage of the resin electrode 32 on the bottom surface 16, the top surface 17, and the first end surface 15A is approximately 67%. On each of the above surfaces, the ratio of the maximum width Wb to the maximum width Wa1: Wb / Wa1 is greater than 1. Specifically, the ratio Wb / Wa1 is approximately 4.3.

[0162] <Evaluation> Coil device 1B was evaluated by simulation in the same manner as in Embodiment 1. Coil device 1B has an element body and metal electrodes with the same configuration as coil device 1, except that one wide, strip-shaped resin electrode 32 is provided approximately at the center of first external electrode 30A in the W direction, and that coil device 1B has metal film 41 covering first and second exposed portions 311, 312.

[0163] The coil device 1B according to this embodiment has the first and second exposed portions 311, 312 at least on the bottom surface 16, and therefore the resistance increase rate is only 30.0% compared to the comparative coil device 2A. On the other hand, the wide strip-shaped resin electrode 32 reduces the deflection stress of the coil device 1B by as much as 65.7%.

[0164] [Fourth embodiment] FIG. 12 is a perspective view showing a fourth embodiment of a coil component, corresponding to FIG. 1 of the first embodiment. The fourth embodiment differs from the first embodiment in the size of the resin electrodes. This difference in configuration will be described below. The configuration of the fourth embodiment is the same as that of the first embodiment except for the size of the resin electrodes, so a description thereof will be omitted. In the fourth embodiment, the same reference numerals as those in the first embodiment represent the same configuration as in the first embodiment, so a description thereof will be omitted. In the fourth embodiment, the manufacturing method is the same as that in the first embodiment, so a description thereof will be omitted.

[0165] The configuration of the first external electrode 30A of the coil component 1C of the fourth embodiment will be described below. The second external electrode 30B has a similar configuration. The resin electrode 32 has two strip-shaped first and second resin electrodes 321 and 322. The first and second resin electrodes 321 and 322 extend continuously in the L direction on the bottom surface 16, the T direction on the first end surface 15A, and the L direction on the top surface 17, in this order. The first resin electrode 321 and the second resin electrode 322 are arranged side by side in the W direction with a gap between them.

[0166] The metal electrode 31 has first, second, and third exposed portions 311, 312, and 313 exposed from the resin electrode 32. The first exposed portion 311 is located at an end of the first side surface 18A on the first end surface 15A side, an end of the bottom surface 16 on the first end surface 15A side and on the first side surface 18A side, an end of the top surface 17 on the first end surface 15A side and on the first side surface 18A side, and an end of the first end surface 15A on the first side surface 18A side. The second exposed portion 312 is located between the first resin electrode 321 and the second resin electrode 322, and is a strip-like portion that extends continuously in the L direction at the bottom surface 16, the T direction at the first end surface 15A, and the L direction at the top surface 17, in this order. The third exposed portion 313 is located at the end of the second side surface 18B on the first end surface 15A side, the end of the bottom surface 16 on the first end surface 15A side and the second side surface 18B side, the end of the top surface 17 on the first end surface 15A side and the second side surface 18B side, and the end of the first end surface 15A on the second side surface 18B side.

[0167] The first exposed portion 311, the first resin electrode 321, the second exposed portion 312, the second resin electrode 322, and the third exposed portion 313 are arranged in this order in the W direction from the first side surface 18A side.

[0168] The coverage of the resin electrode 32 on the bottom surface 16, the top surface 17, and the first end surface 15A is approximately 26%. On each of the above surfaces, the ratio of the maximum width Wb to the maximum width Wa1 (Wb / Wa1) is 1 or less. Specifically, the ratio Wb / Wa1 is approximately 0.45. When the ratio Wb / Wa1 is 1 or less, the effect of suppressing an increase in resistance is particularly likely to be improved. The maximum width Wa2 of the second exposed portion 312 sandwiched between two adjacent first and second resin electrodes 321, 322 is approximately 104 μm.

[0169] <Evaluation> Coil device 1C was evaluated by simulation in the same manner as in the first embodiment. Coil device 1C has an element body and metal electrodes with the same configuration as coil device 1, except that band-shaped resin electrode 32 is narrow and coil device 1C has metal film 41 covering first, second, and third exposed portions 311, 312, and 313.

[0170] The coil device 1C according to this embodiment has the first, second, and third exposed portions 311, 312, and 313 at least on the bottom surface 16, and therefore the resistance increase rate is only 8.9% compared to the comparative coil device 2A. On the other hand, the first and second resin electrodes 321 and 322 reduce the deflection stress of the coil device 1C by as much as 23.1%.

[0171] [Fifth embodiment] FIG. 13 is a perspective view showing a coil component according to a fifth embodiment, corresponding to FIG. 1 of the first embodiment. The fifth embodiment differs from the first embodiment in the size, number, and arrangement of the resin electrodes. This difference in configuration will be described below. The configuration of the fifth embodiment is the same as that of the first embodiment except for the size, number, and arrangement of the resin electrodes, and therefore a description thereof will be omitted. In the fifth embodiment, the same reference numerals as those in the first embodiment represent the same configuration as in the first embodiment, and therefore a description thereof will be omitted. In the fifth embodiment, the manufacturing method is the same as that of the first embodiment, and therefore a description thereof will be omitted.

[0172] The configuration of the first external electrode 30A of the coil device 1D of the fifth embodiment will be described below. The second external electrode 30B has a similar configuration. The metal electrode 31 has, in order from the first side surface 18A side, strip-shaped first and second exposed portions 311 and 312 exposed from the resin electrode 32. The two strip-shaped first and second exposed portions 311 and 312 each extend continuously in the L direction on the bottom surface 16, the T direction on the first end surface 15A, and the L direction on the top surface 17, in this order. The first exposed portion 311 and the second exposed portion 312 are arranged side by side in the W direction with a gap between them.

[0173] The resin electrode 32 has first, second, and third resin electrodes 321, 322, and 323. The first resin electrode 321 is provided on an end of the first side surface 18A facing the first end surface 15A, an end of the bottom surface 16 facing the first end surface 15A and facing the first side surface 18A, an end of the top surface 17 facing the first end surface 15A and facing the first side surface 18A, and an end of the first end surface 15A facing the first side surface 18A. The second resin electrode 322 is located between the first exposed portion 311 and the second exposed portion 312, and has a strip shape that extends continuously in the L direction on the bottom surface 16, the T direction on the first end surface 15A, and the L direction on the top surface 17, in this order. The third resin electrode 323 is provided on an end portion of the second side surface 18B on the first end surface 15A side, an end portion of the bottom surface 16 on the first end surface 15A side and the second side surface 18B side, an end portion of the top surface 17 on the first end surface 15A side and the second side surface 18B side, and an end portion of the first end surface 15A on the second side surface 18B side.

[0174] The first resin electrode 321, the first exposed portion 311, the second resin electrode 322, the second exposed portion 312, and the third resin electrode 323 are arranged side by side in this order in the W direction from the first side surface 18A side. The first and third resin electrodes 321, 323 are provided on the first and second side surfaces 18A, 18B sides of the element body 10, respectively.

[0175] The coverage of the resin electrode 32 on the bottom surface 16, the top surface 17, and the first end surface 15A is approximately 70%. On each of the above surfaces, the ratio of the maximum width Wb to the maximum width Wa1 (Wb / Wa1) is greater than 1. Specifically, the ratio Wb / Wa1 is approximately 2.0. The maximum width Wa2 of the first exposed portion 311 sandwiched between two adjacent first and second resin electrodes 321, 322 and the second exposed portion 312 sandwiched between two adjacent second and third resin electrodes 322, 323 are both approximately 104 μm.

[0176] <Evaluation> Coil device 1D was evaluated by simulation in the same manner as in Embodiment 1. Coil device 1D has an element body and metal electrodes with the same configuration as coil device 1, except that a strip-shaped second resin electrode 322 is provided substantially in the center of first external electrode 30A in the W direction, first and third resin electrodes 321, 323 are provided at both ends of first external electrode 30A in the W direction, and coil device 1D has metal film 41 covering first and second exposed portions 311, 312.

[0177] The coil device 1D according to this embodiment has the first and second exposed portions 311, 312 at least on the bottom surface 16, and therefore the resistance increase rate is only 41.1% compared to the comparative coil device 2A. On the other hand, the first, second, and third resin electrodes 321, 322, and 323 reduce the deflection stress of the coil device 1D by as much as 48.4%.

[0178] [Sixth embodiment] FIG. 14 is a perspective view showing a sixth embodiment of a coil device, corresponding to FIG. 1 of the first embodiment. The sixth embodiment differs from the first embodiment in the size, number, and arrangement of the resin electrodes. FIGS. 15A and 15B are perspective views showing a modified example of the sixth embodiment. The modified example shown in FIGS. 15A and 15B differs from the sixth embodiment in the arrangement of the resin electrodes on each end face. These different configurations are described below. The configuration of the sixth embodiment is the same as that of the first embodiment except for the size, number, and arrangement of the resin electrodes, and therefore a description thereof will be omitted. In the sixth embodiment, the same reference numerals as those in the first embodiment represent the same configuration as in the first embodiment, and therefore a description thereof will be omitted. In the sixth embodiment, the manufacturing method is the same as that of the first embodiment, and therefore a description thereof will be omitted.

[0179] The configuration of the first external electrode 30A of the coil component 1E of the sixth embodiment will be described below. The second external electrode 30B has a similar configuration. The metal electrode 31 has, in order from the first side surface 18A side, first, second, and third strip-shaped exposed portions 311, 312, and 313 exposed from the resin electrode 32. The three strip-shaped first, second, and third exposed portions 311, 312, and 313 each extend continuously in the L direction on the bottom surface 16, the T direction on the first end surface 15A, and the L direction on the top surface 17, in this order. The first exposed portion 311, the second exposed portion 312, and the third exposed portion 313 are arranged side by side in the W direction at intervals from one another.

[0180] The resin electrode 32 has first, second, third, and fourth resin electrodes 321, 322, 323, and 324. The first resin electrode 321 is provided on an end of the first side surface 18A facing the first end surface 15A, an end of the bottom surface 16 facing the first end surface 15A and facing the first side surface 18A, an end of the top surface 17 facing the first end surface 15A and facing the first side surface 18A, and an end of the first end surface 15A facing the first side surface 18A. The second resin electrode 322 is located between the first exposed portion 311 and the second exposed portion 312, and has a strip shape that extends continuously in the L direction on the bottom surface 16, the T direction on the first end surface 15A, and the L direction on the top surface 17, in this order. The third resin electrode 323 is located between the second exposed portion 312 and the third exposed portion 313, and has a strip shape that extends continuously in the L direction on the bottom surface 16, the T direction on the first end surface 15A, and the L direction on the top surface 17, in that order. The fourth resin electrode 324 is provided on an end portion of the second side surface 18B on the first end surface 15A side, an end portion of the bottom surface 16 on the first end surface 15A side and the second side surface 18B side, an end portion of the top surface 17 on the first end surface 15A side and the second side surface 18B side, and an end portion of the first end surface 15A on the second side surface 18B side.

[0181] The first resin electrode 321, the first exposed portion 311, the second resin electrode 322, the second exposed portion 312, the third resin electrode 323, the third exposed portion 313, and the fourth resin electrode 324 are arranged side by side in the W direction in this order from the first side surface 18A side. The first and fourth resin electrodes 321, 324 are provided on the first and second side surfaces 18A, 18B sides of the element body 10, respectively.

[0182] The coverage of the resin electrode 32 on the bottom surface 16, the top surface 17, and the first end surface 15A is approximately 55%. On each of the above surfaces, the ratio Wb / Wa1 of the maximum width Wb to the maximum width Wa1 is equal to or less than 1. Specifically, the ratio Wb / Wa1 is approximately 1.0. The maximum width Wa2 of the first exposed portion 311 sandwiched between two adjacent first and second resin electrodes 321, 322, the second exposed portion 312 sandwiched between two adjacent second and third resin electrodes 322, 323, and the second exposed portion 312 sandwiched between two adjacent third and fourth resin electrodes 323, 324 is all approximately 110 μm.

[0183] (Variation) 15A shows a coil device 1Ea according to a modified example of the present embodiment. In the coil device 1Ea, the first, second, third, and fourth resin electrodes 321, 322, 323, and 324 are all provided in a region extending from the bottom surface 16 side of each end face 15A and 15B to ⅙ of the height T of the element body 10. The first exposed portion 311 is a continuous region of the metal electrode 31 other than the first, second, third, and fourth resin electrodes 321, 322, 323, and 324.

[0184] 15B shows a coil device 1Eb according to a modified example of the present embodiment. In the coil device 1Eb, the first, second, third, and fourth resin electrodes 321, 322, 323, and 324 are all provided in a region extending from the bottom surface 16 side of each end face 15A and 15B to one-third of the height T of the element body 10. The first exposed portion 311 is a continuous region of the metal electrode 31 other than the first, second, third, and fourth resin electrodes 321, 322, 323, and 324.

[0185] These modifications also provide the effect of reducing the deflection stress.

[0186] <Evaluation> Coil devices 1E, 1Ea, and 1Eb were evaluated by simulation in the same manner as in the first embodiment. Coil device 1E has an element body and metal electrodes with the same configuration as coil device 1, except that band-shaped second and third resin electrodes 322 and 323 are provided near the center of first external electrode 30A in the W direction, first and fourth resin electrodes 321 and 324 are provided at both ends of first external electrode 30A in the W direction, and coil device 1E has metal film 41 covering first, second, and third exposed portions 311, 312, and 313.

[0187] Coil component 1Ea has an element body and metal electrodes of the same configuration as coil component 1, except that the first, second, third, and fourth resin electrodes 321, 322, 323, and 324 are all arranged in an area extending from the bottom surface 16 side of each end face 15A and 15B to 1 / 6 of the height T of the element body 10, and that it has a metal film 41 covering the first exposed portion 311.

[0188] Coil component 1Eb has an element body and metal electrodes of the same configuration as coil component 1, except that the first, second, third, and fourth resin electrodes 321, 322, 323, and 324 are all arranged in an area extending from the bottom surface 16 side of each end face 15A and 15B to 1 / 3 of the height T of the element body 10, and that it has a metal film 41 covering the first exposed portion 311.

[0189] The coil component 1E according to this embodiment has the first, second, and third exposed portions 311, 312, and 313 at least on the bottom surface 16, and therefore the resistance increase rate is only 31.0% compared to the comparative coil component 2A. Meanwhile, the first, second, third, and fourth resin electrodes 321, 322, 323, and 324 reduce the deflection stress by 30.8%. The coil component 1Ea according to this embodiment also has the first exposed portion 311 at least on the bottom surface 16, and therefore the resistance increase rate is only 23.7%. Meanwhile, the first, second, third, and fourth resin electrodes 321, 322, 323, and 324 reduce the deflection stress by 32.6%. The coil component 1Eb according to this embodiment also has the first exposed portion 311 at least on the bottom surface 16, and therefore the resistance increase rate is only 30.1%. On the other hand, the first, second, third and fourth resin electrodes 321, 322, 323 and 324 reduce the deflection stress by as much as 31.3%.

[0190] [Seventh embodiment] FIG. 16 is a perspective view showing a seventh embodiment of a coil component, corresponding to FIG. 1 of the first embodiment. The seventh embodiment differs from the first embodiment in the size, number, and arrangement of the resin electrodes. This different configuration will be described below. The configuration of the seventh embodiment is the same as that of the first embodiment except for the size, number, and arrangement of the resin electrodes, so a description thereof will be omitted. In the seventh embodiment, the same reference numerals as those in the first embodiment represent the same configuration as in the first embodiment, so a description thereof will be omitted. In the seventh embodiment, the manufacturing method is the same as that of the first embodiment, so a description thereof will be omitted.

[0191] The configuration of the first external electrode 30A of the coil component 1F of the seventh embodiment will be described below. The second external electrode 30B has a similar configuration. The metal electrode 31 has, in order from the first side surface 18A side, strip-shaped first and second exposed portions 311 and 312 exposed from the resin electrode 32. The two strip-shaped first and second exposed portions 311 and 312 each extend continuously in the L direction on the bottom surface 16, the T direction on the first end surface 15A, and the L direction on the top surface 17, in this order. The first exposed portion 311 and the second exposed portion 312 are arranged side by side in the W direction with a gap between them.

[0192] The resin electrode 32 has first, second, and third resin electrodes 321, 322, and 323. The first resin electrode 321 is provided on an end of the first side surface 18A facing the first end surface 15A, an end of the bottom surface 16 facing the first end surface 15A and facing the first side surface 18A, an end of the top surface 17 facing the first end surface 15A and facing the first side surface 18A, and an end of the first end surface 15A facing the first side surface 18A. The second resin electrode 322 is located between the first exposed portion 311 and the second exposed portion 312, and has a strip shape that extends continuously in the L direction on the bottom surface 16, the T direction on the first end surface 15A, and the L direction on the top surface 17, in this order. The third resin electrode 323 is provided on an end portion of the second side surface 18B on the first end surface 15A side, an end portion of the bottom surface 16 on the first end surface 15A side and the second side surface 18B side, an end portion of the top surface 17 on the first end surface 15A side and the second side surface 18B side, and an end portion of the first end surface 15A on the second side surface 18B side.

[0193] The first resin electrode 321, the first exposed portion 311, the second resin electrode 322, the second exposed portion 312, and the third resin electrode 323 are arranged side by side in this order in the W direction from the first side surface 18A side. The first and third resin electrodes 321, 323 are provided on the first and second side surfaces 18A, 18B sides of the element body 10, respectively.

[0194] The coverage of the resin electrode 32 on the bottom surface 16, the top surface 17, and the first end surface 15A is approximately 45%. On each of the above surfaces, the ratio Wb / Wa1 of the maximum width Wb to the maximum width Wa1 is 1 or less. Specifically, the ratio Wb / Wa1 is approximately 0.6. The maximum width Wa2 of the first exposed portion 311 sandwiched between two adjacent first and second resin electrodes 321, 322 and the second exposed portion 312 sandwiched between two adjacent second and third resin electrodes 322, 323 are both approximately 210 μm. This embodiment, in which the coverage is less than 50% and the ratio Wb / Wa is 1 or less, is particularly effective in suppressing an increase in resistance.

[0195] <Evaluation> Coil device 1F was evaluated by simulation in the same manner as in Embodiment 1. Coil device 1F has an element body and metal electrodes with the same configuration as coil device 1, except that a strip-shaped second resin electrode 322 is provided substantially in the center of first external electrode 30A in the W direction, first and third resin electrodes 321, 323 are provided at both ends of first external electrode 30A in the W direction, and coil device 1F has metal film 41 covering first and second exposed portions 311, 312.

[0196] The coil device 1F according to this embodiment has the first and second exposed portions 311, 312 at least on the bottom surface 16, and therefore the increase in resistance value is limited to 24.3% compared to the comparative coil device 2A.

[0197] [Eighth embodiment] FIG. 17 is a perspective view showing an eighth embodiment of a coil component, corresponding to FIG. 1 of the first embodiment. The eighth embodiment differs from the first embodiment in the size and arrangement of the resin electrodes. This difference in configuration will be described below. The configuration of the eighth embodiment is the same as that of the first embodiment except for the size and arrangement of the resin electrodes, so a description thereof will be omitted. In the eighth embodiment, the same reference numerals as those in the first embodiment represent the same configuration as in the first embodiment, so a description thereof will be omitted. In the eighth embodiment, the manufacturing method is the same as that of the first embodiment, so a description thereof will be omitted.

[0198] The following describes the configuration of the first external electrode 30A of the coil component 1G of the eighth embodiment. The second external electrode 30B has a similar configuration. The metal electrode has one strip-shaped first exposed portion 311. First exposed portion 311 extends continuously in the L direction on bottom surface 16, in the T direction on first end surface 15A, and in the L direction on top surface 17, in this order.

[0199] The resin electrode 32 has first and second resin electrodes 321 and 322. The first resin electrode 321 is provided on an end of the first side surface 18A on the first end surface 15A side, an end of the bottom surface 16 on the first end surface 15A side and the first side surface 18A side, an end of the top surface 17 on the first end surface 15A side and the first side surface 18A side, and an end of the first end surface 15A on the first side surface 18A side. The second resin electrode 322 is provided on an end of the second side surface 18B on the first end surface 15A side, an end of the bottom surface 16 on the first end surface 15A side and the second side surface 18B side, an end of the top surface 17 on the first end surface 15A side and the second side surface 18B side, and an end of the first end surface 15A on the second side surface 18B side.

[0200] The first resin electrode 321, the first exposed portion 311, and the second resin electrode 322 are arranged side by side in this order in the W direction from the first side surface 18A side. The first and second resin electrodes 322 are provided on the first and second side surfaces 18A and 18B sides of the element body 10, respectively.

[0201] The coverage of the resin electrode 32 on the bottom surface 16, the top surface 17, and the first end surface 15A is approximately 30%. On each of the above surfaces, the ratio of the maximum width Wb to the maximum width Wa1 (Wb / Wa1) is 1 or less. Specifically, the ratio Wb / Wa1 is approximately 0.2. The maximum width Wa2 of the first exposed portion 311 sandwiched between two adjacent first and second resin electrodes 321, 322 is approximately 540 μm. This embodiment is also particularly effective in suppressing an increase in resistance.

[0202] <Evaluation> Coil device 1G was evaluated by simulation in the same manner as in the first embodiment. Coil device 1G has an element body and metal electrodes with the same configuration as coil device 1, except that first and second resin electrodes 321, 322 are provided at both ends of first external electrode 30A in the W direction, and coil device 1G has metal film 41 covering first exposed portion 311.

[0203] The coil device 1G according to this embodiment has the first exposed portion 311 at least on the bottom surface 16, and therefore the resistance increase rate is limited to 18.3%.

[0204] The present disclosure is not limited to the above-described embodiments, and design modifications are possible within the scope of the present disclosure. For example, various combinations of the features of the first to eighth embodiments may be used. The number, arrangement, and size of the resin electrodes may be modified.

[0205] In the first to eighth embodiments, a coil component has been described as an example of an electronic component, but the electronic component according to the present disclosure is not limited to a coil component. The electronic component according to the present disclosure may be an active component or a passive component other than a coil component. An active component is a component that amplifies, rectifies, or converts supplied power. Examples of active components include transistors and various sensors. A passive component is a component that consumes, stores, or releases supplied power, but does not perform active operations such as amplification or rectification. In addition to coil components, examples of passive components include resistors, capacitors, and thermistors.

[0206] The arrangement of the metal electrodes 31 is not limited to the above embodiment. The metal electrode 31 may be provided only on the bottom surface 16, or may be L-shaped and extend from the first end surface 15A or the second end surface 15B to the bottom surface 16.

[0207] The arrangement of the resin electrodes 32 is not limited to the above embodiment. The resin electrode 32 may be provided only on the bottom surface 16, or may be L-shaped and extend from the first end surface 15A or the second end surface 15B to the bottom surface 16.

[0208] The resin electrode 32 may cover the entire surface of the metal electrode 31 provided on the first and second end faces 15A and 15B. The resin electrode 32 may cover the entire surface of the metal electrode 31 provided on the top surface 17.

[0209] The shape, arrangement, coverage, size, etc. of the resin electrode 32 on the top surface 17 may be the same as or different from the resin electrode 32 on the bottom surface 16 .

[0210] The number of resin electrodes 32 is not limited to that in the above embodiment. At least one resin electrode 32 may be provided on the bottom surface 16 .

[0211] The thickness of the resin electrode 32 is not limited to that in the above embodiment. The thickness of the resin electrode 32 may be uniform or non-uniform. The thickness of the resin electrode 32 on each surface may be the same or different. The thicknesses of the multiple resin electrodes 32 provided on the same surface may be the same or different.

[0212] The shape, number, arrangement, coverage, size, etc. of the resin electrode 32 provided on the first end face 15A side of the bottom face 16 may be the same as or different from the resin electrode 32 provided on the second end face 15B side of the bottom face 16.

[0213] The shape, number, arrangement, coverage, size, etc. of the resin electrodes 32 provided on the first end face 15A may be the same as or different from those of the resin electrodes 32 provided on the second end face 15B.

[0214] The shape, number, arrangement, coverage, size, etc. of the resin electrode 32 provided on the first end face 15A side of the top surface 17 may be the same as or different from the resin electrode 32 provided on the second end face 15B side of the top surface 17.

[0215] The shape of the element body 10 is not limited to the above-described embodiment. Bottom surface 16 does not have to be continuous with both first end surface 15A and second end surface 15B. Bottom surface 16 may be divided into, for example, a first bottom surface that is continuous only with first end surface 15A and a second bottom surface that is continuous only with second end surface 15B.

[0216] The arrangement of the exposed portion and the resin electrode 32 is not limited to the above embodiment. In at least a part of the region where the metal electrode 31 is provided on the bottom surface 16, the exposed portion and the resin electrode 32 may be arranged side by side in the W direction. For example, in a part of the region where the metal electrode 31 is provided on the bottom surface 16, only the exposed portion may be provided from one end to the other end in the W direction of the bottom surface 16. In a part of the region where the metal electrode 31 is provided on the bottom surface 16, only the resin electrode 32 may be provided from one end to the other end in the W direction of the bottom surface 16.

[0217] This application claims priority based on Japanese Patent Application No. 2022-051695, filed on March 28, 2022, the entire contents of which are incorporated herein by reference. <1> The base body and an external electrode provided on the element body, The element body is A first end surface; a second end surface facing the first end surface; a bottom surface perpendicular to the first end surface and the second end surface, The external electrode is a first external electrode provided on the first end surface side; a second external electrode provided on the second end surface side, The first external electrode is a metal electrode provided on at least a portion of the bottom surface; a resin electrode that covers a part of the portion of the metal electrode that is provided on the bottom surface, The electronic component has, on the bottom surface, an exposed portion of the metal electrode that is exposed from the resin electrode. <2> Further, a plating layer is provided on the bottom surface to cover at least a part of the first external electrode. <1> The electronic component according to claim 1. <3> The direction in which the first end surface and the second end surface face each other is referred to as the L direction, and The direction perpendicular to the L direction on the bottom surface is defined as the W direction, On the bottom surface, The exposed portion and the resin electrode are arranged side by side in the W direction. <1> or <2> The electronic component according to claim 1. <4> The direction in which the first end surface and the second end surface face each other is referred to as the L direction, and The direction perpendicular to the L direction on the bottom surface is defined as the W direction, The exposed portions are provided at both ends of the bottom surface in the W direction. <1> from <3> 1. An electronic component according to any one of the preceding claims. <5> The direction in which the first end surface and the second end surface face each other is referred to as the L direction, and The direction perpendicular to the L direction on the bottom surface is defined as the W direction, On the bottom surface, The resin electrodes are provided so as to sandwich the exposed portion from both sides in the W direction. <1> from <4> 1. An electronic component according to any one of the preceding claims. <6> On the bottom surface, a maximum width of the resin electrode in the W direction is wider than a maximum width of the exposed portion adjacent to the resin electrode in the W direction; <3> from <5> 1. An electronic component according to any one of the preceding claims. <7> On the bottom surface, The maximum width of the exposed portion sandwiched between the two resin electrodes is 10 μm or more and 160 μm or less. <3> from <6> 1. An electronic component according to any one of the preceding claims. <8> In the first external electrode, the metal electrode is further provided on a portion of at least one of the first end surface and the second end surface, the resin electrode further covers a part of a portion of the metal electrode provided on at least one of the first end surface and the second end surface. <1> from <7> 1. An electronic component according to any one of the preceding claims. <9> The direction in which the first end surface and the second end surface face each other is called the L direction. The direction perpendicular to the L direction on the bottom surface is the W direction, and The direction perpendicular to both the L direction and the W direction is defined as the T direction, In the first external electrode, The resin electrode provided on a portion of at least one of the first end face and the second end face is provided in a region of the end face on which the resin electrode is provided, from the bottom surface side to ½ of the height of the element body in the T direction. <8> The electronic component according to claim 1. <10> The direction in which the first end surface and the second end surface face each other is called the L direction. The direction perpendicular to the L direction on the bottom surface is the W direction, and The direction perpendicular to both the L direction and the W direction is defined as the T direction, The resin electrode provided on the bottom surface protrudes outward in the T direction from the surface of the metal electrode provided on the bottom surface. <1> from <9> 1. An electronic component according to any one of the preceding claims. <11> Further, a metal film is provided to cover at least an exposed portion of the metal electrode that is exposed from the resin electrode. <1> from <10> 1. An electronic component according to any one of the preceding claims. <12> At least on the bottom surface, the surface of the resin electrode and the surface of the metal film are flush with each other. <11> The electronic component according to claim 1. <13> The resin electrode provided on the bottom surface is symmetrical with respect to a line that passes through the center of the bottom surface and extends in an L direction in which the first end surface and the second end surface face each other. <1> from <12> 1. An electronic component according to any one of the preceding claims. <14> The resin electrode provided on the bottom surface has a uniform thickness. <1> from <13> 1. An electronic component according to any one of the preceding claims. <15> The direction in which the first end surface and the second end surface face each other is called the L direction. The direction perpendicular to the L direction on the bottom surface is the W direction, and The direction perpendicular to both the L direction and the W direction is defined as the T direction, In a cross section of the resin electrode, the cross section is parallel to a TW plane formed by a line extending in the W direction and a line extending in the T direction, a width of a first surface of the resin electrode provided on the bottom surface on the side of the metal electrode is narrower than a width of a second surface of the resin electrode on the opposite side to the first surface; <1> from <14> 1. An electronic component according to any one of the preceding claims. <16> Further, the magnetron includes a coil provided inside the element body, The coil is electrically connected to the first external electrode and the second external electrode, respectively. <1> from <15> 1. An electronic component according to any one of the preceding claims. <17> preparing an element body having a first end surface, a second end surface opposite to the first end surface, and a bottom surface perpendicular to the first end surface and the second end surface; providing a first external electrode on the first end surface side; and providing a second external electrode on the second end surface side. The step of providing the first external electrode includes: forming a metal electrode on at least a portion of the bottom surface on the first end face side; forming a resin electrode that covers a portion of the portion of the metal electrode that is provided on the bottom surface; In the step of forming the resin electrode, an exposed portion of the metal electrode is formed, the exposed portion being exposed from the resin electrode. <18> The step of forming the resin electrode includes: applying a conductive resin composition containing a photosensitive resin to at least a portion of the portion of the metal electrode provided on the bottom surface; irradiating a portion of the applied resin composition with laser light; and removing the part or remainder of the resin composition after the irradiating step. <17> A method for manufacturing the electronic component according to claim 1. <19> After the step of forming the resin electrode, forming a metal film covering at least the exposed portion of the metal electrode; <17> or <18> A method for manufacturing the electronic component according to claim 1. [Explanation of symbols]

[0218] 1,1A~1G,1Ea,1Eb Coil parts 10 Base 15A 1st end face 15B 2nd end face 16 Bottom 17 Top 18A 1st side 18B 2nd side 20 coils 21 Magnetic layer 22 Coil wiring 23A First lead conductor 23B Second lead conductor 24 Via wiring 30A 1st external electrode 30B 2nd external electrode 31 Metal electrode 311 1st exposed part 312 2nd exposed part 313 Third exposed part 3101 1st metal part 3102 Second metal part 3103 Third metal part 32 Resin electrode 321 1st resin electrode 322 2nd resin electrode 323 Third resin electrode 324 4th resin electrode 3201 1st resin part 3202 2nd resin part 3203 3rd resin part 40 plating layer 41 Metal Film Coil parts for comparison between 2A and 2B 5. Solder 6 pads

Claims

1. The base body and an external electrode provided on the element body, The element body is A first end surface; a second end surface facing the first end surface; a bottom surface perpendicular to the first end surface and the second end surface, The external electrode is a first external electrode provided on the first end surface side; a second external electrode provided on the second end surface side, The first external electrode is a metal electrode provided on at least a portion of the bottom surface; a resin electrode that covers a part of the portion of the metal electrode that is provided on the bottom surface, the metal electrode has an exposed portion on the bottom surface that is exposed from the resin electrode; The resin electrode is formed from a conductive resin composition containing a photosensitive resin, and the electronic component includes a cured product of the resin composition.

2. The electronic component according to claim 1 , further comprising a plating layer on the bottom surface that covers at least a portion of the first external electrode.

3. The direction in which the first end surface and the second end surface face each other is referred to as an L direction, and The direction perpendicular to the L direction on the bottom surface is defined as a W direction, On the bottom surface, The electronic component according to claim 1 , wherein the exposed portion and the resin electrode are arranged side by side in the W direction.

4. The direction in which the first end surface and the second end surface face each other is referred to as an L direction, and The direction perpendicular to the L direction on the bottom surface is defined as a W direction, The electronic component according to claim 1 , wherein the exposed portions are provided at both ends of the bottom surface in the W direction.

5. The direction in which the first end surface and the second end surface face each other is referred to as an L direction, and The direction perpendicular to the L direction on the bottom surface is defined as a W direction, On the bottom surface, The electronic component according to claim 1 , wherein the resin electrodes are provided so as to sandwich the exposed portion from both sides in the W direction.

6. On the bottom surface, 6. The electronic component according to claim 3, wherein the maximum width of the resin electrode in the W direction is greater than the maximum width of the exposed portion adjacent to the resin electrode in the W direction.

7. On the bottom surface, 6. The electronic component according to claim 3, wherein the maximum width of the exposed portion sandwiched between the two resin electrodes is 10 μm or more and 160 μm or less.

8. In the first external electrode, the metal electrode is further provided on a portion of at least one of the first end surface and the second end surface, The electronic component according to claim 1 , wherein the resin electrode further covers a part of a portion of the metal electrode provided on at least one of the first end face and the second end face.

9. The direction in which the first end surface and the second end surface face each other is called the L direction. The direction perpendicular to the L direction on the bottom surface is the W direction, and A direction perpendicular to both the L direction and the W direction is defined as a T direction, In the first external electrode, 9. The electronic component according to claim 8, wherein the resin electrode provided on a portion of at least one of the first end face and the second end face is provided in a region of the end face on which the resin electrode is provided, from the bottom side to 1 / 2 of the height of the element body in the T direction.

10. The direction in which the first end surface and the second end surface face each other is called the L direction. The direction perpendicular to the L direction on the bottom surface is the W direction, and A direction perpendicular to both the L direction and the W direction is defined as a T direction, 3. The electronic component according to claim 1, wherein the resin electrode provided on the bottom surface protrudes outward in the T direction beyond a surface of the metal electrode provided on the bottom surface.

11. The electronic component according to claim 1 , further comprising a metal film covering at least a portion of the metal electrode that is exposed from the resin electrode.

12. The electronic component according to claim 11 , wherein at least on the bottom surface, a surface of the resin electrode and a surface of the metal film are flush with each other.

13. 3. The electronic component according to claim 1, wherein the resin electrode provided on the bottom surface is symmetrical with respect to a line that passes through a center of the bottom surface and extends in an L direction in which the first end surface and the second end surface face each other.

14. 3. The electronic component according to claim 1, wherein the resin electrode provided on the bottom surface has a uniform thickness.

15. The direction in which the first end surface and the second end surface face each other is called the L direction. The direction perpendicular to the L direction on the bottom surface is the W direction, and A direction perpendicular to both the L direction and the W direction is defined as a T direction, In a cross section of the resin electrode, the cross section is parallel to a T-W plane formed by a line extending in the W direction and a line extending in the T direction, 3 . The electronic component according to claim 1 , wherein a width of a first surface of the resin electrode provided on the bottom surface on the side of the metal electrode is narrower than a width of a second surface of the resin electrode on the opposite side to the first surface.

16. Further, the magnetron includes a coil provided inside the element body, The electronic component according to claim 1 , wherein the coil is electrically connected to the first external electrode and the second external electrode, respectively.

17. preparing an element body having a first end surface, a second end surface opposite to the first end surface, and a bottom surface perpendicular to the first end surface and the second end surface; providing a first external electrode on the first end surface side; and providing a second external electrode on the second end surface side. The step of providing the first external electrode includes: forming a metal electrode on at least a portion of the bottom surface on the first end surface side; forming a resin electrode that covers a portion of the portion of the metal electrode that is provided on the bottom surface; The step of forming the resin electrode includes: applying a conductive resin composition containing a photosensitive resin to at least a portion of the portion of the metal electrode provided on the bottom surface; irradiating a portion of the applied resin composition with laser light; and removing the part or remainder of the resin composition after the irradiating step, In the step of forming the resin electrode, an exposed portion of the metal electrode is formed, the exposed portion being exposed from the resin electrode; The resin electrode includes a cured product of the resin composition.

18. After the step of forming the resin electrode, The method for manufacturing an electronic component according to claim 17 , further comprising the step of forming a metal film that covers at least the exposed portion of the metal electrode.

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