Stacked inductor
By introducing auxiliary conductors to connect with through conductors and external electrodes in a multilayer inductor, a multilayer structure is formed, which solves the problem of overheating and melting at the joint surface caused by through conductor failure, and improves the reliability and connectivity of the inductor.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- TDK CORP
- Filing Date
- 2022-03-22
- Publication Date
- 2026-06-05
AI Technical Summary
Existing multilayer inductors are prone to overheating and potential melting at the junction when the through conductor fails, affecting reliability.
An auxiliary conductor is introduced into the inductor. The auxiliary conductor is joined with the through conductor and the external electrode to form a multi-layer structure. This ensures that the current is shunted through the auxiliary conductor when the through conductor fails, thus avoiding overheating and melting at the joint surface.
It improves the reliability of inductors, suppresses overheating and melting at the junction, enhances connectivity, prevents current concentration during through-conductor faults, and achieves high reliability.
Smart Images
Figure CN115116716B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to multilayer inductors. Background Technology
[0002] Currently, an inductor comprising a through conductor extending linearly within a body is known. Japanese Utility Model Application Publication No. 59-72708 discloses an inductor comprising: a body having a pair of opposite end faces; three through conductors extending between the end faces; and a pair of external electrodes disposed on the two end faces of the body and connected to each through conductor.
[0003] As with the inductors described in the prior art, when the through conductors are doubled (i.e., current flows through each of the multiple through conductors connected in parallel), a current within a specified current range flows through each of the multiple through conductors. In the event of a fault such as a break in one of the through conductors, a current exceeding the specified current range (overcurrent) flows through the remaining through conductors. In this case, the junction between the through conductor and the external electrode, which is a region with relatively high resistance, overheats, potentially causing melting starting from the junction. Summary of the Invention
[0004] According to one aspect of the present invention, a multilayer inductor with improved reliability is provided.
[0005] A multilayer inductor according to one aspect of the present invention includes: a body comprising a plurality of stacked magnetic body layers and having a pair of end faces opposite each other; an internal electrode disposed within the body and extending between the pair of end faces; and a pair of external electrodes disposed on the end faces of the body and engaged with the internal electrodes exposed on the end faces, wherein the internal electrodes have: a plurality of through conductors extending between the end faces along the opposite direction of the pair of end faces and exposed at the end ends of the end faces; and auxiliary conductors extending between the ends of the plurality of through conductors and exposed on the end faces.
[0006] In the above-mentioned multilayer inductor, since it includes an auxiliary conductor that is joined to the external electrode at the end face of the core, even if a portion of the through conductor fails, it is possible to suppress overheating at the joint surface between the internal and external electrodes and suppress melting starting from the joint surface, thus achieving high reliability.
[0007] In other types of multilayer inductors, the internal electrodes are located between a single layer of multiple magnetic layers.
[0008] In other types of multilayer inductors, the internal electrodes are located between multiple layers of multiple magnetic material layers.
[0009] In other types of multilayer inductors, multiple through conductors include a pair of through conductors arranged along the stacking direction of the substrate.
[0010] In other aspects of multilayer inductors, the multiple through conductors include: a first through conductor and a second through conductor located between the same layers of multiple magnetic body layers; and a third through conductor and a fourth through conductor located in the same layer, different from the interlayer of the first through conductor and the second through conductor, and arranged along the stacking direction of the body with the first through conductor and the second through conductor, respectively.
[0011] In other types of multilayer inductors, the length of the auxiliary conductor in the first direction, which is orthogonal to the stacking direction of the substrate and the relative directions of a pair of end faces, is 20 to 50% of the length of the substrate in the first direction.
[0012] In other types of multilayer inductors, the length of the auxiliary conductor in the second direction, which is parallel to the opposite direction of a pair of end faces, is 2 to 20% of the length of the main body in the second direction. Attached Figure Description
[0013] Figure 1 This is a perspective view showing a multilayer inductor according to an embodiment.
[0014] Figure 2 It means Figure 1 A three-dimensional view of the internal electrodes of the substrate shown.
[0015] Figure 3 It means Figure 2 A top view of the internal electrodes shown.
[0016] Figure 4 yes Figure 2 The figure shown is a cross-sectional view along line IV-IV.
[0017] Figure 5 yes Figure 2 The figure shown is a cross-sectional view of the VV line of the solid.
[0018] Figure 6 It is a cross-sectional view showing the connection state between the internal and external electrodes.
[0019] Figure 7 It means and Figure 4 Top view of internal electrodes in different configurations.
[0020] Figure 8 It means and Figure 2 Three-dimensional views of the internal electrodes of the substrate in different configurations.
[0021] Figure 9 yes Figure 8 The figure shown is a cross-sectional view along line IX-IX.
[0022] Figure 10 It means and Figure 8 Three-dimensional views of the internal electrodes of the substrate in different configurations. Detailed Implementation
[0023] Hereinafter, with reference to the accompanying drawings, a mode for carrying out the invention will be described. In the description of the drawings, the same or equivalent elements are referred to by the same reference numerals, and repeated descriptions are omitted.
[0024] Reference Figures 1-4 The structure of the multilayer inductor involved in the embodiment will be described. For example... Figure 1 As shown, the stacked inductor 10 according to the embodiment is configured to include a body 12 and a pair of external electrodes 14A, 14B.
[0025] The body 12 has a generally rectangular parallelepiped shape and a pair of end faces 12a and 12b that face each other in the extending direction of the body 12. The body 12 also has four side faces 12c to 12f that extend in the opposite direction of the end faces 12a and 12b and connect the end faces 12a and 12b to each other. Side face 12d is the mounting surface that faces the mounting substrate when mounting the multilayer inductor 10, and side face 12c, which faces side face 12d, becomes the top surface during mounting. Assuming that the dimension in the opposite direction of the end faces 12a and 12b is the length (L), the dimension in the opposite direction of the side faces 12e and 12f is the width (W), and the dimension in the opposite direction of the side faces 12c and 12d is the thickness, as an example, the dimensions of the body 12 are 2.5 mm in length × 2 mm in width × 0.9 mm in thickness.
[0026] The base body 12 has a structure in which an internal electrode 20 is disposed inside the magnetic body 18. For example... Figure 4 As shown, the base body 12 has a stacked structure in which multiple magnetic body layers 19 constituting the magnetic body 18 are stacked in the opposite directions of the sides 12c and 12d. In the following description, the opposite directions of the sides 12c and 12d are also referred to as the stacking direction of the base body 12.
[0027] The magnetic body 18 is made of a magnetic material such as ferrite. The magnetic body 18 is obtained by stacking and firing multiple magnetic pastes (e.g., ferrite pastes) that form magnetic body layers 19. That is, the substrate 12 has a printed layer structure with magnetic body layers 19 printed with magnetic paste, and is a fired substrate formed by stacking the fired magnetic body layers 19. For example, the number of magnetic body layers 19 constituting the substrate 12 is 150 layers. In the actual substrate 12, the multiple magnetic body layers 19 are integrated to the point that the boundaries between the layers are indistinguishable.
[0028] like Figure 2 and Figure 3As shown, the internal electrode 20 extends between a pair of end faces 12a and 12b. Additionally, as... Figure 4 As shown, the internal electrode 20 is situated entirely between a single layer of multiple magnetic layers 19. The internal electrode 20 is made of, for example, a conductive material containing a metal such as Ag. The internal electrode 20 is formed by a printing method. Specifically, it is obtained by coating a conductive paste (e.g., Ag paste) that will become the internal electrode 20 onto the magnetic paste that becomes the magnetic layer 19 and then firing it.
[0029] The internal electrode 20 is configured to include a pair of through conductors 22 and 24 extending in opposite directions along end faces 12a and 12b. Both through conductors 22 and 24 extend between end faces 12a and 12b (i.e., from end face 12a to end face 12b of the body 12). Through conductor 22 has an end 22a on the end face 12a side and an end 22b on the end face 12b side; similarly, through conductor 24 has an end 24a on the end face 12a side and an end 24b on the end face 12b side. Through conductor 22 is exposed at end 22a on end face 12a and at end 22b on end face 12b. Similarly, through conductor 24 is exposed at end 24a on end face 12a and at end 24b on end face 12b.
[0030] In this embodiment, each through conductor 22, 24 is in the form of a strip with uniform width and uniform height. For example... Figure 5 As shown, in this embodiment, the through conductors 22 and 24 are cross-sections orthogonal to the opposite directions of the end faces 12a and 12b. The cross-sectional shape of each through conductor 22 has two rounded corners on the side furthest from the mounting surface (a so-called semi-cylindrical cross-section) of a rectangle extending parallel to the mounting surface (side surface 12c). The cross-sectional shape of each through conductor 22 and 24 can be either a rectangle extending parallel to the mounting surface or a semi-elliptical shape with a flat mounting surface side. In this embodiment, each through conductor 22 and 24 has a uniform width and uniform height throughout its entire length. In this embodiment, the through conductors 22 and 24 have the same dimensions; for example, a length of 2.5 mm × a width of 0.4 mm × a thickness of 0.1 mm.
[0031] The internal electrode 20 also includes a pair of auxiliary conductors 26 and 28. The auxiliary conductor 26 extends between the end 22a of the through conductor 22 and the end 24a of the through conductor 24. The auxiliary conductor 28 extends between the end 22b of the through conductor 22 and the end 24b of the through conductor 24. Each auxiliary conductor 26 and 28 is integrally formed with the pair of through conductors 22 and 24. Each auxiliary conductor 26 and 28 extends along end faces 12a and 12b and is exposed along its entire length in the width direction (opposite directions of sides 12e and 12f) of the body 12. In this embodiment, each auxiliary conductor 26 and 28 is a strip extending in the width direction of the body 12, having a uniform width and a uniform height. In this embodiment, the auxiliary conductors 26 and 28 have the same dimensions; for example, a length of 0.1 mm × a width of 0.4 mm × a thickness of 0.1 mm. The lengths of the auxiliary conductors 26 and 28 can also be in the range of 0.1 to 1.0 mm.
[0032] A pair of external electrodes 14A and 14B are respectively disposed on the end faces 12a and 12b of the body 12. External electrode 14A covers the entire area of end face 12a and is in direct contact with and engaged with the through conductors 22 and 24 and the auxiliary conductor 26 of the internal electrode 20 exposed on end face 12a. Similarly, external electrode 14B covers the entire area of end face 12b and is in direct contact with and engaged with the through conductors 22 and 24 and the auxiliary conductor 28 of the internal electrode 20 exposed on end face 12b. In this embodiment, as... Figure 1 As shown, each of the external electrodes 14A and 14B integrally covers the end faces 12a and 12b and the side faces 12c to 12f of the region adjacent to the end faces 12a and 12b.
[0033] Each external electrode 14A, 14B is composed of one or more electrode layers. The electrode material constituting each external electrode 14A, 14B can be, for example, a metallic material such as Ag. In this embodiment, as... Figure 6 As shown, each external electrode 14A, 14B is composed of two electrode layers 15 and 16. The first electrode layer 15 is located on the side of the substrate 12, directly covering the end faces 12a, 12b. The first electrode layer 15 is composed of a sintered electrode or a resin electrode including Ag and glass. The second electrode layer 16 is located on the outer side, completely covering the surface of the first electrode layer 15. The second electrode layer 16 is composed of a plated electrode. The second electrode layer 16 can be composed of multiple plating layers, and can be composed of three layers (Cu / Ni / Sn) or two layers (Ni / Sn, Ni / Au).
[0034] Figure 7 This refers to a body 12 having an internal electrode 20 that does not include the aforementioned auxiliary conductors 26 and 28. (Construction) Figure 7The through conductors 22 and 24 of the internal electrode 20 are joined to the external electrodes 14A and 14B at end faces 12a and 12b. Figure 7 In the shown body 12, the junction surface S between the internal electrode 20 and the external electrodes 14A and 14B (refer to...) Figure 6 The junction S is a region with relatively high resistance, and when a specified current flows between the external electrodes 14A and 14B, the junction surface S is prone to overheating. Especially in the event of a fault such as a broken conductor (e.g., conductor 22), the current flowing from both conductors into another conductor (e.g., conductor 24) can cause overheating of the junction surface S between the other conductor and the external electrodes 14A and 14B, potentially leading to melting originating from the junction surface S. A broken conductor could, for example, be caused by bending or twisting of the conductor due to internal stress.
[0035] The multilayer inductor 10 in this embodiment is as follows: Figure 3 The internal electrode 20 shown includes auxiliary conductors 26 and 28, which are connected to the external electrodes 14A and 14B at end faces 12a and 12b. Specifically, on end faces 12a and 12b, the internal electrode 20 has through conductors 22 and 24 connected to the external electrodes 14A and 14B, and the auxiliary conductors 26 and 28 are also connected to the external electrodes 14A and 14B. Therefore, in the event of a failure in one of the through conductors, current flows through the remaining through conductors, and also through the auxiliary conductors. This suppresses overheating at the junction surface S between the remaining through conductors and the external electrodes 14A and 14B and prevents melting originating from the junction surface S. Thus, high reliability is achieved in the multilayer inductor 10.
[0036] Furthermore, since the junction surface S between the internal electrode 20 and the external electrodes 14A and 14B is enlarged, high connectivity between the internal electrode 20 and the external electrodes 14A and 14B is achieved, and the peeling of the internal electrode 20 from the external electrodes 14A and 14B is effectively suppressed.
[0037] Furthermore, the length W1 of the auxiliary conductors 26 and 28 in the width direction (first direction) of the body 12 can also be 20 to 50% of the length W of the body 12 in the first direction.
[0038] In addition, the length L1 of the auxiliary conductors 26 and 28 in the opposite direction (second direction) of the end faces 12a and 12b can also be 2 to 20% of the length L of the body 12 in the second direction.
[0039] The aforementioned internal electrode 20 can also be as follows Figure 8 The diagram shows a configuration consisting of multiple internal electrodes 20A and 20B. In this case, as... Figure 8 As shown, Figure 8The two internal electrodes 20A and 20B shown are located between two different layers of the plurality of magnetic layers 19. Each internal electrode 20A and 20B has the same shape and size as the internal electrode 20 described above, including through conductors 22 and 24 and auxiliary conductors 26 and 28. Therefore, the through conductor 22 (first through conductor) of internal electrode 20A and the through conductor 22 (third through conductor) of internal electrode 20B are arranged along the stacking direction of the body 12. Similarly, the through conductor 24 (second through conductor) of internal electrode 20A and the through conductor 24 (fourth through conductor) of internal electrode 20B are arranged along the stacking direction of the body 12.
[0040] exist Figure 8 and Figure 9 In the structure shown, if a portion of the through conductor fails, current flows through the remaining through conductors, and current also flows through the auxiliary conductors. Therefore, overheating at the junction surface S of the internal electrodes 20A, 20B and the external electrodes 14A, 14B can be suppressed, and melting originating from the junction surface S can be suppressed.
[0041] In addition, such as Figure 10 As shown, the structure can also be configured to include auxiliary conductors 29 extending between the ends 22a and 22b of the through conductor 22 that runs along end faces 12a and 12b and throughout the internal electrodes 20A and 20B, and auxiliary conductors 29 extending between the ends 24a and 24b of the through conductor 24 that runs along end faces 12a and 12b and throughout the internal electrodes 20A and 20B. Each auxiliary conductor 29 extends along the stacking direction of the body 12, for example, in a prismatic shape.
Claims
1. A multilayer inductor, characterized in that, include: The base body comprises multiple stacked magnetic layers and has a pair of end faces facing each other; Internal electrodes, disposed within the body, extending throughout the space between the pair of end faces; and A pair of external electrodes are respectively disposed on the end face of the substrate and engage with the internal electrodes exposed on the end face. The internal electrodes have: A plurality of through conductors extending between the pair of end faces in opposite directions, and exposed at their ends on the end faces; and A pair of auxiliary conductors, each extending between the ends of at least one pair of through conductors, and exposed on the pair of end faces and respectively engaged with the pair of external electrodes on the pair of end faces.
2. The multilayer inductor as described in claim 1, characterized in that, The internal electrode is located in a single interlayer of the plurality of magnetic layers.
3. The multilayer inductor as described in claim 1, characterized in that, The internal electrodes are located between multiple layers of the plurality of magnetic layers.
4. The multilayer inductor as described in claim 3, characterized in that, The plurality of through conductors includes a pair of through conductors arranged along the stacking direction of the substrate.
5. The multilayer inductor as described in claim 3, characterized in that, The plurality of through conductors include: The first through conductor and the second through conductor are located in the same layer between the plurality of magnetic body layers; The third and fourth through conductors are located in the same interlayer, different from the interlayer of the first and second through conductors, and are arranged along the stacking direction of the substrate, respectively, with respect to the first and second through conductors.
6. The multilayer inductor as described in any one of claims 1 to 5, characterized in that, The length of the auxiliary conductor in a first direction orthogonal to the stacking direction of the substrate and the relative directions of the pair of end faces is 20 to 50% of the length of the substrate in the first direction.
7. The multilayer inductor as described in any one of claims 1 to 5, characterized in that, The length of the auxiliary conductor in a second direction parallel to the relative directions of the pair of end faces is 2 to 20% of the length of the body in the second direction.