JP6675933B2 - Laminated coil parts - Google Patents

Description

  The present invention relates to a laminated coil component.

  2. Description of the Related Art An electronic component including a body and external electrodes arranged on the surface of the body is known (for example, see Patent Document 1). In the electronic component described in Patent Document 1, the external electrode has a base metal layer formed on the surface of the element body and a conductive resin layer formed so as to cover the base metal layer. ing.

Japanese Patent No. 5172818

  An object of one embodiment of the present invention is to provide a laminated coil component in which deterioration of electrical characteristics of the laminated coil component is suppressed even if a crack occurs in the element body.

  The laminated coil component according to one embodiment of the present invention, a body, a coil disposed in the body, an external electrode disposed on the surface of the body, and electrically connected to the coil, The element body has a main surface that is a mounting surface, and an end surface that is located adjacent to the main surface and extends in a direction intersecting the main surface, and the external electrode includes a main surface. A base metal layer formed on the surface and the end surface, and a conductive resin layer formed so as to cover the base metal layer. It is located outside the coil when viewed from a direction perpendicular to the plane.

  As a result of the research by the present inventors, the following matters have been found. For example, when the laminated coil component is mounted on an electronic device (for example, a circuit board or an electronic component), an external force acting on the laminated coil component from the electronic device may act as a stress on the element through an external electrode. . At this time, since the stress tends to concentrate on the end of the base metal layer located on the main surface which is the mounting surface, cracks occur in the element body starting from the end of the base metal layer. There is a risk.

  In the laminated coil component according to the one aspect of the present invention, even when a crack occurs in the element body starting from the end of the base metal layer, the end of the base metal layer is orthogonal to the main surface. Since it is located outside the coil when viewed from the direction, it is difficult for the generated crack to reach the coil. Therefore, even if a crack occurs in the element body, the crack hardly affects the coil, and the deterioration of the electrical characteristics of the laminated coil component is suppressed.

  The thickness of the conductive resin layer at the end of the base metal layer may be 50% or more of the maximum thickness at a portion located on the main surface of the conductive resin layer.

  As a result of the research by the present inventors, the following matters have been found. Since the conductive resin layer generally contains a metal powder and a resin (for example, a thermosetting resin), the conductive resin layer has a higher resistance than the metal base layer. Therefore, when the external electrode has the conductive resin layer, the DC resistance of the laminated coil component may increase. In order to suppress an increase in the DC resistance of the laminated coil component, it is conceivable to reduce the thickness of the conductive resin layer and reduce the resistance of the conductive resin layer. However, in this case, the stress relaxation effect of the conductive resin layer may be reduced.

  In this embodiment, the thickness of the conductive resin layer at the end of the base metal layer is set to 50% or more of the maximum thickness at a portion located on the main surface of the conductive resin layer. For this reason, even when an external force acts on the laminated coil component, stress is unlikely to concentrate on the above-described end of the base metal layer, and the end is unlikely to be a starting point of a crack. Therefore, even when the thickness of the conductive resin layer is reduced, a decrease in the stress relaxation effect of the conductive resin layer is suppressed.

  With the plane including the end face as the reference plane, the reference in the direction perpendicular to the end face with respect to the length from the reference plane in the direction perpendicular to the end face to the position of the maximum thickness in the portion located on the main surface of the conductive resin layer The ratio of the length from the surface to the end of the base metal layer may be 0.6 to 1.0. In this case, the reduction of the stress relaxation effect by the conductive resin layer is further suppressed.

  Further comprising a conductor which is disposed in the element body and has one end connected to the coil and the other end exposed to the end face and connected to the underlying metal layer, from a direction orthogonal to the end face. As seen, the position where the other end of the conductor is exposed on the end surface may be different from the position of the maximum thickness in the portion located on the main surface of the conductive resin layer.

  As a result of the research by the present inventors, the following matters have been found. The underlying metal layer is generally composed of a sintered metal layer. Since the sintered metal layer is a layer formed by sintering the metal component (metal powder) contained in the conductive paste, it is difficult for the sintered metal layer to become a uniform metal layer. Is hard to control. The sintered metal layer may have, for example, a shape in which a plurality of openings (through holes) are formed (a mesh shape or the like).

  The conductive resin layer is a layer in which metal powder is dispersed in a cured resin. In the conductive resin layer, a current path is formed by contact between the metal powders. It is difficult to control the dispersion state of the metal powder in the resin, and it is difficult to control the position of the current path in the conductive resin layer.

  For these reasons, the current paths in the conductive resin layer and the underlying metal layer differ from product to product. In some products, for example, a row of metal powder is formed at the position of the maximum thickness in a portion located on the end face of the conductive resin layer, and the metal powder and the mesh-shaped base metal layer are in contact with each other. In this product, when viewed from a direction perpendicular to the end face, the position where the other end of the conductor is exposed on the end face matches the position of the maximum thickness in the portion located on the main surface of the conductive resin layer. In this case, the current flows into the other end of the conductor through the current path formed at the position of the maximum thickness in the portion located on the main surface of the conductive resin layer, so that the DC resistance is high. In order to obtain a product having a low DC resistance, even if a current path is formed at the position of the maximum thickness in a portion located on the main surface of the conductive resin layer, the probability that a current flows through the current path is low. It is necessary to adopt.

  In the present embodiment, when viewed from a direction perpendicular to the end face, the position where the other end of the conductor is exposed on the end face is different from the position of the maximum thickness in the portion located on the main surface of the conductive resin layer. Therefore, there is a high possibility that electricity will flow to the end of the conductor through the current path formed at a position other than the position of the maximum thickness in the portion located on the main surface of the conductive resin layer. Therefore, according to the present embodiment, it is difficult to obtain a laminated coil component having a high DC resistance.

  When viewed from a direction perpendicular to the main surface, the end of the base metal layer may be positioned closer to the end surface than the position of the maximum thickness of the portion located on the main surface of the conductive resin layer. In the present embodiment, for example, as compared with a configuration in which the end portion of the base metal layer is located farther from the end surface than the position of the maximum thickness in the portion located on the main surface of the conductive resin layer, The end of the layer moves away from the coil. Therefore, even when a crack occurs in the element body starting from the end portion of the base metal layer, the generated crack does not easily reach the coil. Therefore, even if a crack occurs in the element body, the crack hardly affects the coil, and the deterioration of the electrical characteristics of the laminated coil component is suppressed.

  According to the one aspect of the present invention, it is possible to provide a laminated coil component in which deterioration of electrical characteristics of the laminated coil component is suppressed even if a crack occurs in the element body.

It is a perspective view showing the lamination coil component concerning one embodiment. It is a figure for explaining section composition of a lamination coil component concerning this embodiment. It is a perspective view showing composition of a coil conductor. FIG. 3 is a diagram for explaining a cross-sectional configuration of an external electrode. FIG. 3 is a diagram for explaining a cross-sectional configuration of an external electrode. It is a top view of the element body in which the 1st electrode layer was formed. It is a top view of the 2nd electrode layer which the electrode part located in an end surface contains. It is a top view of the 2nd electrode layer which the electrode part located in an end surface contains.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same elements or elements having the same functions will be denoted by the same reference symbols, without redundant description.

  The configuration of the laminated coil component 1 according to the present embodiment will be described with reference to FIGS. FIG. 1 is a perspective view showing a laminated coil component according to the present embodiment. FIG. 2 is a diagram for explaining a cross-sectional configuration along the line II-II in FIG. FIG. 3 is a perspective view showing the configuration of the coil conductor.

  As shown in FIG. 1, the laminated coil component 1 includes a body 2 having a rectangular parallelepiped shape, and a pair of external electrodes 4 and 5. The pair of external electrodes 4 and 5 are arranged at both ends of the element body 2 and are separated from each other. The rectangular parallelepiped shape includes a rectangular parallelepiped shape in which corners and ridges are chamfered, and a rectangular parallelepiped in which the corners and ridges are rounded. The laminated coil component 1 can be applied to, for example, a bead inductor or a power inductor.

  The element body 2 has a rectangular parallelepiped shape. The element body 2 has, as its surfaces, a pair of end surfaces 2a and 2b facing each other, a pair of main surfaces 2c and 2d facing each other, and a pair of side surfaces 2e and 2f facing each other. ing. The end surfaces 2a and 2b are located so as to be adjacent to the pair of main surfaces 2c and 2d. The end surfaces 2a and 2b are positioned so as to be adjacent to the pair of side surfaces 2e and 2f. The main surface 2c or the main surface 2d is, for example, a surface (mounting surface) facing the other electronic device when the laminated coil component 1 is mounted on another electronic device not shown (for example, a circuit board or an electronic component). ).

  In the present embodiment, the direction in which the pair of end surfaces 2a and 2b face each other (first direction D1) is the length direction of the element body 2. The direction in which the pair of main surfaces 2c and 2d face each other (second direction D2) is the height direction of the element body 2. The direction in which the pair of side surfaces 2e and 2f face each other (third direction D3) is the width direction of the element body 2. The first direction D1, the second direction D2, and the third direction D3 are orthogonal to each other.

  The length of the element body 2 in the first direction D1 is larger than the length of the element body 2 in the second direction D2 and the length of the element body 2 in the third direction D3. The length of the element body 2 in the second direction D2 is equal to the length of the element body 2 in the third direction D3. That is, in the present embodiment, the pair of end surfaces 2a and 2b have a square shape, and the pair of main surfaces 2c and 2d and the pair of side surfaces 2e and 2f have a rectangular shape. The length of the element body 2 in the first direction D1 may be equal to the length of the element body 2 in the second direction D2 and the length of the element body 2 in the third direction D3. The length of the element body 2 in the second direction D2 and the length of the element body 2 in the third direction D3 may be different.

  The term “equal” means that, in addition to being equal, a value including a small difference or a manufacturing error in a preset range may be equal. For example, if a plurality of values are included in a range of ± 5% of the average value of the plurality of values, it is defined that the plurality of values are equivalent.

  Each end face 2a, 2b extends in the second direction D2 so as to connect the pair of main faces 2c, 2d. That is, the end surfaces 2a and 2b extend in a direction intersecting the main surfaces 2c and 2d. Each end face 2a, 2b also extends in the third direction D3. The pair of main surfaces 2c, 2d extend in the first direction D1 so as to connect the pair of end surfaces 2a, 2b. The pair of main surfaces 2c and 2d also extend in the third direction D3. The pair of side surfaces 2e and 2f extend in the second direction D2 so as to connect between the pair of main surfaces 2c and 2d. The pair of side surfaces 2e and 2f also extend in the first direction D1.

  The element body 2 is configured by stacking a plurality of insulator layers 6 (see FIG. 3). Each insulator layer 6 is stacked in a direction in which the main surface 2c and the main surface 2d face each other. That is, the lamination direction of each insulator layer 6 matches the direction in which the main surface 2c and the main surface 2d face each other. Hereinafter, the direction in which the main surface 2c and the main surface 2d face each other is also referred to as a “stacking direction”. Each insulator layer 6 has a substantially rectangular shape. In the actual element 2, the insulator layers 6 are integrated so that the boundaries between the layers are not visible.

  Each insulator layer 6 is a sintered body of a ceramic green sheet containing a ferrite material (for example, a Ni-Cu-Zn-based ferrite material, a Ni-Cu-Zn-Mg-based ferrite material, or a Ni-Cu-based ferrite material). Consists of That is, the element body 2 is made of a ferrite sintered body.

  The laminated coil component 1 includes a coil 15 arranged in the element body 2. As shown in FIG. 3, the coil 15 includes a plurality of coil conductors (a plurality of internal conductors) 16a, 16b, 16c, 16d, 16e, and 16f. The plurality of coil conductors 16a to 16f include a conductive material (for example, Ag or Pd). The plurality of coil conductors 16a to 16f are configured as a sintered body of a conductive paste containing a conductive material (for example, Ag powder or Pd powder).

  The coil conductor 16a includes a connection conductor 17. The connection conductor 17 is arranged on the end face 2b side of the element body 2 and has an end exposed on the end face 2b. The end of the connection conductor 17 is exposed at a position closer to the main surface 2c than the central region of the end surface 2b when viewed from a direction orthogonal to the end surface 2b. The coil conductor 16a is connected to the external electrode 5 at the end of the connection conductor 17 exposed on the end face 2b. That is, the coil conductor 16a is electrically connected to the external electrode 5 through the connection conductor 17. In the present embodiment, the conductor pattern of the coil conductor 16a and the conductor pattern of the connection conductor 17 are formed integrally and continuously.

  The coil conductor 16f includes the connection conductor 18. The connection conductor 18 is arranged on the end face 2a side of the element body 2 and has an end exposed on the end face 2a. The end of the connection conductor 18 is exposed at a position closer to the main surface 2d than the central region of the end surface 2a when viewed from a direction orthogonal to the end surface 2a. The coil conductor 16f is connected to the external electrode 4 at the end of the connection conductor 18 exposed on the end face 2a. That is, the coil conductor 16f is electrically connected to the external electrode 4 through the connection conductor 18. In the present embodiment, the conductor pattern of the coil conductor 16f and the conductor pattern of the connection conductor 18 are integrally and continuously formed.

  The plurality of coil conductors 16a to 16f are juxtaposed in the element body 2 in the direction in which the insulator layers 6 are stacked. The plurality of coil conductors 16a to 16f are arranged in the order of coil conductor 16a, coil conductor 16b, coil conductor 16c, coil conductor 16d, coil conductor 16e, and coil conductor 16f from the side closest to the outermost layer. In the present embodiment, the coil 15 includes a portion other than the connection conductor 17 in the coil conductor 16a, a plurality of coil conductors 16b to 16d, and a portion other than the connection conductor 18 in the coil conductor 16f.

  The ends of the coil conductors 16a to 16f are connected by through-hole conductors 19a to 19e. The coil conductors 16a to 16f are electrically connected to each other by the through-hole conductors 19a to 19e. The coil 15 is configured such that a plurality of coil conductors 16a to 16f are electrically connected. Each of the through-hole conductors 19a to 19e includes a conductive material (for example, Ag or Pd). Each of the through-hole conductors 19a to 19e, like the plurality of coil conductors 16a to 16f, is configured as a sintered body of a conductive paste containing a conductive material (for example, Ag powder or Pd powder).

  The external electrode 4 is located at an end of the element body 2 on the end face 2a side when viewed in the first direction D1. The external electrode 4 has an electrode portion 4a located on the end surface 2a, an electrode portion 4b located on a pair of main surfaces 2c and 2d, and an electrode portion 4c located on a pair of side surfaces 2e and 2f. ing. That is, the external electrodes 4 are formed on five surfaces 2a, 2c, 2d, 2e, and 2f.

  The electrode portions 4a, 4b, 4c adjacent to each other are connected to each other at the ridge of the element body 2 and are electrically connected. The electrode portion 4a and the electrode portion 4b are connected at a ridge between the end surface 2a and each of the main surfaces 2c and 2d. The electrode portion 4a and the electrode portion 4c are connected at a ridge between the end face 2a and each of the side faces 2e and 2f.

  The electrode portion 4a is arranged so as to cover the entire end exposed on the end face 2a of the connection conductor 18, and the connection conductor 18 is directly connected to the external electrode 4. That is, the connection conductor 18 connects the coil conductor 16a (one end of the coil 15) and the electrode portion 4a. Thus, the coil 15 is electrically connected to the external electrode 4.

  The external electrode 5 is located at an end of the element body 2 on the end face 2b side when viewed in the first direction D1. The external electrode 5 has an electrode portion 5a located on the end surface 2b, an electrode portion 5b located on a pair of main surfaces 2c, 2d, and an electrode portion 5c located on a pair of side surfaces 2e, 2f. ing. That is, the external electrodes 5 are formed on five surfaces 2b, 2c, 2d, 2e, and 2f.

  The electrode portions 5a, 5b, 5c adjacent to each other are connected at the ridge of the element body 2 and are electrically connected. The electrode portion 5a and the electrode portion 5b are connected at a ridge portion between the end face 2b and each of the main faces 2c and 2d. The electrode portion 5a and the electrode portion 5c are connected at a ridge portion between the end face 2b and each of the side faces 2e and 2f.

  The electrode portion 5a is arranged so as to cover the entire end exposed on the end face 2b of the connection conductor 17, and the connection conductor 17 is directly connected to the external electrode 5. That is, the connection conductor 17 connects the coil conductor 16f (the other end of the coil 15) and the electrode portion 5a. Thus, the coil 15 is electrically connected to the external electrode 5.

  The external electrodes 4 and 5 have a first electrode layer 21, a second electrode layer 23, a third electrode layer 25, and a fourth electrode layer 27, respectively, as shown in FIGS. That is, the electrode portions 4a, 4b, 4c and the electrode portions 5a, 5b, 5c include the first electrode layer 21, the second electrode layer 23, the third electrode layer 25, and the fourth electrode layer 27, respectively. The fourth electrode layer 27 forms the outermost layer of the external electrodes 4 and 5. 4 and 5 are diagrams for explaining a cross-sectional configuration of the external electrode.

  The first electrode layer 21 is formed by applying and baking a conductive paste to the surface of the element body 2. The first electrode layer 21 is a sintered metal layer formed by sintering a metal component (metal powder) contained in the conductive paste. That is, the first electrode layer 21 is a sintered metal layer formed on the element body 2. In the present embodiment, the first electrode layer 21 is a sintered metal layer made of Ag. The first electrode layer 21 may be a sintered metal layer made of Pd. Thus, the first electrode layer 21 contains Ag or Pd. As the conductive paste, a mixture of a powder of Ag or Pd mixed with a glass component, an organic binder, and an organic solvent is used.

  The second electrode layer 23 is formed by curing a conductive resin provided on the first electrode layer 21. The second electrode layer 23 is formed so as to cover the entire first electrode layer 21. The first electrode layer 21 is a base metal layer for forming the second electrode layer 23. The second electrode layer 23 is a conductive resin layer formed on the first electrode layer 21. As the conductive resin, a mixture of a thermosetting resin, a metal powder, an organic solvent, and the like is used. As the metal powder, for example, Ag powder or the like is used. As the thermosetting resin, for example, a phenol resin, an acrylic resin, a silicone resin, an epoxy resin, a polyimide resin, or the like is used.

  The third electrode layer 25 is formed on the second electrode layer 23 by a plating method. In the present embodiment, the third electrode layer 25 is a Ni plating layer formed on the second electrode layer 23 by Ni plating. The third electrode layer 25 may be a Sn plating layer, a Cu plating layer, or an Au plating layer. Thus, the third electrode layer 25 contains Ni, Sn, Cu, or Au.

  The fourth electrode layer 27 is formed on the third electrode layer 25 by a plating method. In the present embodiment, the fourth electrode layer 27 is a Sn plating layer formed on the third electrode layer 25 by Sn plating. The fourth electrode layer 27 may be a Cu plating layer or an Au plating layer. Thus, the fourth electrode layer 27 contains Sn, Cu, or Au. The third electrode layer 25 and the fourth electrode layer 27 constitute a plating layer formed on the second electrode layer 23. That is, in the present embodiment, the plating layer formed on the second electrode layer 23 has a two-layer structure.

  The average thickness of the portions of the first electrode layer 21 located on the end faces 2a and 2b (the average thickness of the first electrode layer 21 included in the electrode portions 4a and 5a) is, for example, 10 to 30 μm. The average thickness of the portions of the second electrode layer 23 located on the end faces 2a and 2b (the average thickness of the second electrode layer 23 included in the electrode portions 4a and 5a) is, for example, 30 to 50 μm. The average thickness of the portion of third electrode layer 25 located on end surfaces 2a and 2b (the average thickness of third electrode layer 25 included in electrode portions 4a and 5a) is, for example, 1 to 3 μm. The average thickness of the portion of the fourth electrode layer 27 located on the end faces 2a and 2b (the average thickness of the fourth electrode layer 27 included in the electrode portions 4a and 5a) is, for example, 2 to 7 μm. The average thickness (the average thickness of the plating layers included in the electrode portions 4a and 5a) of the portions located on the end faces 2a and 2b of the plating layers (the third and fourth electrode layers 25 and 27) is, for example, 3 to 10 μm. .

  The average thickness of the portion of first electrode layer 21 located on main surfaces 2c and 2d (the average thickness of first electrode layer 21 included in electrode portions 4b and 5b) is, for example, 1 to 2 μm. The average thickness of the portion of second electrode layer 23 located on main surfaces 2c and 2d (average thickness of second electrode layer 23 included in electrode portions 4b and 5b) is, for example, 10 to 30 μm. The average thickness of the portion of third electrode layer 25 located on main surfaces 2c and 2d (the average thickness of third electrode layer 25 included in electrode portions 4b and 5b) is, for example, 1 to 3 μm. The average thickness of the portion of fourth electrode layer 27 located on main surfaces 2c and 2d (the average thickness of fourth electrode layer 27 included in electrode portions 4b and 5b) is, for example, 2 to 7 μm. The average thickness (the average thickness of the plating layers included in the electrode portions 4b and 5b) of the portions located on the main surfaces 2c and 2d of the plating layers (the third and fourth electrode layers 25 and 27) is, for example, 3 to 10 μm. is there. The average thickness of the second electrode layer 23 included in the electrode portions 4b and 5b is not more than 15 times the average thickness of the first electrode layer 21 included in the electrode portions 4b and 5b. The average thickness of the second electrode layer 23 included in the electrode portions 4b and 5b is not more than five times the average thickness of the plating layer included in the electrode portions 4b and 5b.

  The average thickness can be determined, for example, as follows.

  A cross-sectional view including each part located on the end faces 2a and 2b of the first electrode layer 21, the second electrode layer 23, the third electrode layer 25, and the fourth electrode layer 27 is obtained. The cross-sectional view is, for example, a sectional view taken along a plane which is parallel to a pair of surfaces facing each other (for example, a pair of side surfaces 2e and 2f) and is equidistant from the pair of surfaces. FIG. 4 is a cross-sectional view of one electrode layer 21, second electrode layer 23, third electrode layer 25, and fourth electrode layer 27. The respective areas of the first electrode layer 21, the second electrode layer 23, the third electrode layer 25, and the portions located on the end faces 2a and 2b of the fourth electrode layer 27 on the obtained cross-sectional view are calculated.

  The area of the portion located on the end surfaces 2a, 2b of the first electrode layer 21 is divided by the length of the portion located on the end surfaces 2a, 2b in the obtained cross-sectional view, and the obtained quotient is the first electrode. The average thickness of a portion of the layer 21 located on the end faces 2a and 2b is used. The area of the portion located on the end surfaces 2a and 2b of the second electrode layer 23 is divided by the length of the portion located on the end surfaces 2a and 2b in the obtained cross-sectional view, and the obtained quotient is divided by the second electrode The average thickness of the portion located on the end faces 2a and 2b of the layer 23 is used. The area of the portion located on the end faces 2a, 2b of the third electrode layer 25 is divided by the length of the portion located on the end faces 2a, 2b in the obtained cross-sectional view, and the obtained quotient is obtained by the third electrode. The average thickness of a portion of the layer 25 located on the end faces 2a and 2b is used. The area of the portion located on the end surfaces 2a and 2b of the fourth electrode layer 27 is divided by the length of the portion located on the end surfaces 2a and 2b in the acquired cross-sectional view, and the obtained quotient is obtained by dividing the obtained quotient by the fourth electrode The average thickness of a portion of the layer 27 located on the end faces 2a and 2b is used.

  A cross-sectional view including each portion of the first electrode layer 21, the second electrode layer 23, the third electrode layer 25, and the fourth electrode layer 27 located on the main surfaces 2c and 2d is obtained. The cross-sectional view is, for example, a sectional view taken along a plane which is parallel to a pair of surfaces facing each other (for example, a pair of side surfaces 2e and 2f) and is equidistant from the pair of surfaces. FIG. 4 is a cross-sectional view of one electrode layer 21, second electrode layer 23, third electrode layer 25, and fourth electrode layer 27. The respective areas of the first electrode layer 21, the second electrode layer 23, the third electrode layer 25, and the portions located on the main surfaces 2c and 2d of the fourth electrode layer 27 on the acquired cross-sectional view are calculated.

  The area of the portion located on the main surfaces 2c and 2d of the first electrode layer 21 is divided by the length of the portion located on the main surfaces 2c and 2d in the obtained sectional view, and the obtained quotient is divided by The average thickness of a portion of the one electrode layer 21 located on the main surfaces 2c and 2d is used. The area of the portion located on the main surfaces 2c and 2d of the second electrode layer 23 is divided by the length of the portion located on the main surfaces 2c and 2d in the obtained sectional view, and the obtained quotient is divided by The average thickness of the portions of the two electrode layers 23 located on the main surfaces 2c and 2d is used. The area of the portion located on the main surfaces 2c and 2d of the third electrode layer 25 is divided by the length of the portion located on the main surfaces 2c and 2d in the acquired cross-sectional view, and the obtained quotient is divided by The average thickness of the portions located on the main surfaces 2c and 2d of the three-electrode layer 25 is used. The area of the portion located on the main surfaces 2c and 2d of the fourth electrode layer 27 is divided by the length of the portion located on the main surfaces 2c and 2d in the obtained cross-sectional view, and the obtained quotient is divided by the fourth. The average thickness of the portions of the four electrode layers 27 located on the main surfaces 2c and 2d is used.

  In any case, a plurality of sectional views may be obtained, and the quotients may be obtained for each of the sectional views. In this case, the average value of the acquired plural quotients may be used as the average thickness.

  Next, the relationship between the first electrode layer 21 and the second electrode layer 23 of the external electrodes 4 and 5 on the main surfaces 2c and 2d will be described with reference to FIGS.

The thickness T _RS1 of the second electrode layer 23 at the end located on the main surfaces 2c and 2d of the first electrode layer 21 is the maximum thickness T _RSmax at the portion of the second electrode layer 23 located on the main surfaces 2c and 2d. 50% or more. That is, the thickness T _RS1 of the second electrode layer 23 located on the end of the first electrode layer 21 included in the electrode portions 4b and 5b is _{equal to} the maximum thickness T _RSmax of the second electrode layer 23 included in the electrode portions 4b and 5b. 50% or more. Maximum thickness T _RSmax is, for example, 11 to ₄₀ μm. The thickness T _RS1 is, for example, 6 to 40 μm. In the present embodiment, the maximum thickness T _RSmax is 30 μm, and the thickness T _RS1 is 20 μm. That is, the thickness T _RS1 is about 67% of the maximum thickness T _RSmax .

In the electrode portion 4b, an end located on the main surfaces 2c and 2d of the first electrode layer 21 is formed on the main surface of the second electrode layer 23 when viewed from a direction orthogonal to the main surfaces 2c and 2d (second direction D2). The portion located on the surfaces 2c and 2d is located closer to the end surface 2a than the position of the maximum thickness _TRSmax . That is, the end of the first electrode layer 21 included in the electrode portion 4b is located closer to the end face 2a than the position of the maximum thickness T _RSmax of the second electrode layer 23 included in the electrode portion 4b when viewed from the second direction D2. ing. The plane including the end surface 2a as a reference plane DP _1, the length _{L SE1} to the end of the first electrode layer 21 from the reference plane DP ₁ comprising the electrode portion 4b in the first direction D1 is in the first direction D1 from the reference plane DP ₁ to the position of the maximum thickness _{T RSmax} of the second electrode layer 23 including the electrode portion 4b is smaller than the length _{L RS1.}

In the electrode portion 5b, the end located on the main surfaces 2c and 2d of the first electrode layer 21 is the largest in the portion located on the main surfaces 2c and 2d of the second electrode layer 23 when viewed from the second direction D2. It is located closer to the end face 2b than the position of the thickness _TRSmax . That is, the end of the first electrode layer 21 included in the electrode portion 5b is located closer to the end face 2b than the position of the maximum thickness T _RSmax of the second electrode layer 23 included in the electrode portion 5b when viewed from the second direction D2. ing. A plane including the end face 2b as a reference plane DP _2, the length _{L SE2} to the end of the first electrode layer 21 from the reference plane DP ₂ comprising the electrode portion 5b in the first direction D1 is in the first direction D1 from the reference plane DP ₂ to the position of the maximum thickness _{T RSmax} of the second electrode layer 23 including the electrode portion 5b smaller than the length _{L RS2.}

The length L _SE1 is, for example, 80 μm. The length L _RS1 is, for example, 120 μm. The length L _SE2 is, for example, 80 μm. Length L _RS2 is, for example, 120 μm. In the present embodiment, the length L _SE1 and the length L _SE2 are equivalent, but the length L _SE1 and the length L _SE2 may be different. In the present embodiment, the length L _RS1 and the length L _RS2 are equivalent, but the length L _RS1 and the length L _RS2 may be different.

  Next, although not shown, the relationship between the first electrode layer 21 and the second electrode layer 23 of the external electrodes 4 and 5 on the side surfaces 2e and 2f will be described.

The thickness of the second electrode layer 23 at the end located on the side surface 2e, 2f of the first electrode layer 21 is 50% or more of the maximum thickness in the portion located on the side surface 2e, 2f of the second electrode layer 23. . That is, the thickness of the second electrode layer 23 located on the end of the first electrode layer 21 included in the electrode portions 4c and 5c is 50% or more of the maximum thickness of the second electrode layer 23 included in the electrode portions 4c and 5c. is there. The thickness of the second electrode layer 23 located on the end of the first electrode layer 21 included in the electrode portions 4c and 5c is equal to the thickness _TRS1 . The maximum thickness of the second electrode layer 23 included in the electrode portions 4c and 5c is equal to the maximum thickness T _RSmax .

  In the electrode portion 4c, the ends located on the side surfaces 2e and 2f of the first electrode layer 21 are viewed from a direction orthogonal to the side surfaces 2e and 2f (third direction D3). It is located closer to the end face 2a than the position of the maximum thickness in the portion located on 2f. That is, the end of the first electrode layer 21 included in the electrode portion 4c is located closer to the end face 2a than the position of the maximum thickness of the second electrode layer 23 included in the electrode portion 4c when viewed from the third direction D3. .

Length from the reference plane DP ₁ in the first direction D1 to the end of the first electrode layer 21 including the electrode portion 4c is equal to the length L _SE1. Length from the reference plane DP ₁ in the first direction D1 to the position of the maximum thickness of the second electrode layer 23 including the electrode portion 4c is equal to the length L _RS1. Accordingly, the second length from the reference plane DP ₁ in the first direction D1 to the end of the first electrode layer 21 including the electrode portion 4c is included in the electrode portion 4c from the reference plane DP ₁ in the first direction D1 It is smaller than the length up to the position of the maximum thickness of the electrode layer 23.

  In the electrode portion 5c, the end located on the side surface 2e, 2f of the first electrode layer 21 has the maximum thickness in the portion located on the side surface 2e, 2f of the second electrode layer 23 when viewed from the third direction D3. It is located closer to the end face 2b than the position. That is, the end of the first electrode layer 21 included in the electrode portion 5c is located closer to the end face 2b than the position of the maximum thickness of the second electrode layer 23 included in the electrode portion 5c when viewed from the third direction D3. .

Length from the reference plane DP ₂ in the first direction D1 to the end of the first electrode layer 21 including the electrode portions 5c are equivalent to the length L _SE2. Length from the reference plane DP ₂ in the first direction D1 to the position of the maximum thickness of the second electrode layer 23 including the electrode portion 5c is equal to the length L _RS2. Accordingly, the second length from the reference plane DP ₂ in the first direction D1 to the end of the first electrode layer 21 including the electrode portion 5c is included in the electrode portion 5c from the reference plane DP ₂ in the first direction D1 It is smaller than the length up to the position of the maximum thickness of the electrode layer 23.

  Next, the relationship between the coil 15 and the first electrode layer 21 will be described with reference to FIG. FIG. 6 is a plan view of the element body on which the first electrode layer is formed.

As shown in FIG. 6, the ends located on the main surfaces 2c and 2d of the first electrode layer 21 (ends of the first electrode layer 21 included in the electrode portions 4b and 5b) are connected to the main surfaces 2c and 2d. It is located outside the coil 15 when viewed from a direction orthogonal to the second direction (second direction D2). That is, the first electrode layer 21 included in the electrode portions 4b and 5b does not overlap with the coil 15 when viewed from a direction orthogonal to the main surfaces 2c and 2d. The length L _SE1 is smaller than the length from the reference plane DP ₁ to the coil 15 in the first direction D1. The length _{L SE2} is smaller than the length from the reference plane DP ₂ in the first direction D1 to the coil 15. Part of the first electrode layer 21 included in the electrode portions 4b and 5b overlaps with the connection conductors 17 and 18 when viewed from the second direction D2.

  Although not shown, the end located on the side surfaces 2e and 2f of the first electrode layer 21 (the end of the first electrode layer 21 included in the electrode portions 4c and 5c) is also in the third direction D3 (the side surfaces 2e and 2f). (In a direction perpendicular to the direction of the coil 15). That is, the first electrode layer 21 included in the electrode portions 4c and 5c does not overlap with the coil 15 when viewed from the third direction D3. Part of the first electrode layer 21 included in the electrode portions 4c and 5c overlaps with the connection conductors 17 and 18 as viewed from the third direction D3.

  Next, the relationship between the coil 15 and the first electrode layer 21 will be described with reference to FIGS. 7 and 8 are plan views of the second electrode layer included in the electrode portion located on the end face.

  4 and 5, the connection conductor 17 has one end connected to the coil 15 and the other end exposed to the end face 2b and connected to the first electrode layer 21. ing. The connection conductor 18 has one end connected to the coil 15 and the other end exposed on the end face 2 a and connected to the first electrode layer 21.

  When forming the second electrode layer 23, the application of the conductive resin is generally realized by an immersion method. In this case, the thickness of the second electrode layer 23 included in the electrode portions 4a and 5a is largest at a position corresponding to the central region of the end surfaces 2a and 2b when viewed from a direction perpendicular to the end surfaces 2a and 2b, and is away from the position. Becomes smaller as

  As shown in FIG. 7, the other end of the connection conductor 17 is exposed at a position closer to the main surface 2c than the central region of the end surface 2b when viewed from a direction orthogonal to the end surface 2b. That is, when viewed from a direction perpendicular to the end face 2b, the position where the other end of the connection conductor 17 is exposed on the end face 2b is different from the position of the maximum thickness of the second electrode layer 23 included in the electrode portion 5a. .

  As shown in FIG. 8, the other end of the connection conductor 18 is exposed at a position closer to the main surface 2d than the central region of the end surface 2a when viewed from a direction orthogonal to the end surface 2a. That is, when viewed from a direction orthogonal to the end face 2a, a position where the other end of the connection conductor 17 is exposed on the end face 2a is different from a position of the maximum thickness of the second electrode layer 23 included in the electrode portion 4a. .

  When the laminated coil component 1 is mounted on an electronic device, an external force acting on the laminated coil component 1 from the electronic device may act as a stress on the element body 2 through the external electrodes 4 and 5. At this time, the stress tends to concentrate on the end of the first electrode layer 21 included in the electrode portions 4b and 5b.

In the laminated coil component 1, the thickness T _RS1 of the second electrode layer 23 located on the end of the first electrode layer 21 included in the electrode portions 4b and 5b is the maximum of the second electrode layer 23 included in the electrode portions 4b and 5b. It is set to be 50% or more of the thickness T _RSmax . For this reason, even when an external force acts on the laminated coil component 1, stress is unlikely to concentrate on the end of the first electrode layer 21 included in the electrode portions 4b and 5b, and the first electrode layer 21 included in the electrode portions 4b and 5b is hardly concentrated. The end is unlikely to be the starting point for cracks. Therefore, even when the thickness of the second electrode layer 23 is reduced, a decrease in the stress relaxation effect of the second electrode layer 23 is suppressed.

Here, the ratio of the thickness T _RS1 to the maximum thickness T _RSmax and the ratio of the lengths L _SE1 and L _SE2 to the lengths L _RS1 and L _RS2 that can suppress the reduction of the stress relaxation effect will be described in detail.

The present inventors conducted the following test in order to clarify the ratio of the thickness T _RS1 to the maximum thickness T _RSmax that can suppress the reduction in the stress relaxation effect. First, a maximum thickness _T plurality of laminated coil component ratio of the thickness _{T RS1} are different for _RSmax (sample S1-S5), performed to a strength test deflection per sample S1-S5. After the bending strength test, the laminated coil component is cut together with a substrate described later, and it is visually confirmed whether or not cracks have occurred in the element body of the laminated coil component.

  In the bending strength test, first, a laminated coil component is solder-mounted on a central portion of a substrate (glass epoxy substrate). The size of the substrate is 100 mm × 40 mm, and the thickness of the substrate is 1.6 mm. Next, the substrate is placed on two bars arranged in parallel with a 90 mm interval. The substrate is placed so that the surface on which the laminated coil component is mounted faces downward. Thereafter, a bending stress is applied to the central portion of the substrate from the back surface of the surface on which the laminated coil component is mounted so that the amount of bending of the substrate becomes a desired value.

The ratio of the thickness T _RS1 to the maximum thickness T _RSmax can be changed by making the lengths L _SE1 and L _SE2 different. For example, when the first electrode layer 21 is formed such that the lengths L _SE1 and L _SE2 match the lengths L _RS1 and L _RS2 , the thickness T _RS1 matches the maximum thickness T _RSmax . In this case, the ratio of the thickness T _RS1 to the maximum thickness T _RSmax is 100%.

The samples S1 to S5 have the same configuration except that the ratio of the thickness T _RS1 to the maximum thickness T _RSmax (the ratio of the lengths L _SE1 and L _SE2 to the lengths L _RS1 and L _RS2 ) is different. In each of the samples S1 to S5, the length of the body 2 in the first direction D1 is set to 1.46 mm, the length of the body 2 in the second direction D2 is set to 0.75 mm, and the length of the body 2 The length in three directions D3 is set to 0.75 mm.

In the sample S1, the ratio of the thickness T _RS1 to the maximum thickness T _RSmax is set to “40%”. At this time, the ratio of the lengths L _SE1 and L _SE2 to the lengths L _RS1 and L _RS2 is “0.2”. The maximum thickness T _RSmax is 30 μm, and the thickness T _RS1 is 12 μm. The lengths L _RS1 and L _RS2 are 120 μm, and the lengths L _SE1 and L _SE2 are 24 μm.

In the sample S2, the ratio of the thickness T _RS1 to the maximum thickness T _RSmax is set to “50%”. At this time, the ratio of the lengths L _SE1 and L _SE2 to the lengths L _RS1 and L _RS2 is “0.6”. The maximum thickness T _RSmax is 30 μm, and the thickness T _RS1 is 15 μm. The lengths L _RS1 and L _RS2 are 120 μm, and the lengths L _SE1 and L _SE2 are 72 μm.

In the sample S3, the ratio of the thickness T _RS1 to the maximum thickness T _RSmax is set to “100%”. At this time, the ratio of the lengths L _SE1 and L _SE2 to the lengths L _RS1 and L _RS2 is “1.0”. The maximum thickness T _RSmax is 30 μm, and the thickness T _RS1 is 30 μm. The lengths L _RS1 and L _RS2 are 120 μm, and the lengths L _SE1 and L _SE2 are 120 μm.

In the sample S4, the ratio of the thickness T _RS1 to the maximum thickness T _RSmax is set to “50%”. At this time, the ratio of the lengths L _SE1 and L _SE2 to the lengths L _RS1 and L _RS2 is “1.6”. The maximum thickness T _RSmax is 30 μm, and the thickness T _RS1 is 15 μm. The lengths L _RS1 and L _RS2 are 120 μm, and the lengths L _SE1 and L _SE2 are 192 μm.

In the sample S5, the ratio of the thickness T _RS1 to the maximum thickness T _RSmax is set to “40%”. At this time, the ratio of the lengths L _SE1 and L _SE2 to the lengths L _RS1 and L _RS2 is “1.8”. The maximum thickness T _RSmax is 30 μm, and the thickness T _RS1 is 12 μm. The lengths L _RS1 and L _RS2 are 120 μm, and the lengths L _SE1 and L _SE2 are 216 μm.

  When bending stress was applied to the substrate so that the amount of bending of the substrate was "5.0 mm", cracks were observed in the element bodies of Sample S1 and Sample S5. On the other hand, in Samples S2, S3, and S4, no crack was observed in the element body.

  When bending stress was applied to the substrate so that the amount of bending of the substrate became “7.0 mm”, cracks were observed in the element bodies of Sample S1, Sample S4, and Sample S5. In contrast, in Samples S2 and S3, no crack was found in the element body.

From the above, when the ratio of the thickness T _RS1 to the maximum thickness T _RSmax is 50% or more, a decrease in the stress relaxation effect is suppressed. Further, when the ratio of the lengths L _SE1 and L _SE2 to the lengths L _RS1 and L _RS2 is in the range of 0.6 to 1.0, the reduction in the stress relaxation effect is further suppressed.

  The end of the first electrode layer 21 included in the electrode portions 4b and 5b is located outside the coil 15 when viewed from the second direction D2. As a result, stress concentrates on the end of the first electrode layer 21 included in the electrode portions 4b and 5b, and even if a crack occurs in the element body from the end as a starting point, the generated crack is removed by the coil 15. Difficult to reach. Therefore, even when a crack occurs in the element body 2, the crack hardly affects the coil 15, and deterioration of the electrical characteristics of the laminated coil component 1 is suppressed.

  Stress is less likely to concentrate at the end of the second electrode layer 23 included in the electrode portions 4b and 5b than at the end of the first electrode layer 21 included in the electrode portions 4b and 5b. Therefore, the end of the second electrode layer 23 included in the electrode portions 4b and 5b may overlap the coil 15 when viewed from the second direction D2.

  The first electrode layer 21 is composed of a sintered metal layer. Since the sintered metal layer is a layer formed by sintering the metal component (metal powder) contained in the conductive paste, it is difficult for the sintered metal layer to become a uniform metal layer. Is hard to control. The sintered metal layer may have, for example, a shape in which a plurality of openings (through holes) are formed (a mesh shape or the like).

  The second electrode layer 23 is a layer in which a metal powder is dispersed in a cured resin. In the second electrode layer 23, a current path is formed by contact between the metal powders. It is difficult to control the dispersion state of the metal powder in the resin, and the position of the current path in the second electrode layer 23 is hard to control.

  For these reasons, the current paths in the second electrode layer 23 and the first electrode layer 21 are different for each product. Depending on the product, for example, a row of metal powder is formed at the position of the maximum thickness of the second electrode layer 23 included in the electrode portions 4a, 5a, and the metal powder contacts the mesh-shaped first electrode layer 21. . In this product, when viewed from the first direction D1, the position where the other ends of the connection conductors 17 and 18 are exposed on the end surfaces 2b and 2a, and the position where the second electrode layer 23 included in the electrode portions 5a and 4a has the maximum thickness. Is equal to the current flowing through the other end of the connection conductors 17 and 18 through the current path formed at the position of the maximum thickness of the second electrode layer 23 included in the electrode portions 4a and 5a, Is high. In order to obtain a product having a low DC resistance, even if a current path is formed at the position of the maximum thickness of the second electrode layer 23 included in the electrode portions 5a and 4a, the probability that a current flows through the current path is low. It is necessary to adopt.

  In the laminated coil component 1 according to the present embodiment, as viewed from the first direction D1, the positions where the other ends of the connection conductors 17 and 18 are exposed on the end faces 2b and 2a, and the second electrodes included in the electrode portions 4a and 5a. Since the position of the maximum thickness of the layer 23 is different from that of the connection conductors 17 and 18 through the current paths formed at positions other than the position of the maximum thickness of the second electrode layer 23 included in the electrode portions 4a and 5a. It is highly possible that electricity flows to the other end of the. Therefore, according to the present embodiment, it is difficult to obtain the laminated coil component 1 having a high DC resistance.

The end of the first electrode layer 21 included in the electrode portion 4b is located closer to the end face 2a than the position of the maximum thickness T _RSmax of the second electrode layer 23 included in the electrode portion 4b when viewed from the second direction D2. . In this case, the end of the first electrode layer 21 included in the electrode portion 4b is located farther from the end surface 2a than the position of the maximum thickness T _RSmax of the second electrode layer 23 included in the electrode portion 4b. As a result, the end of the first electrode layer 21 included in the electrode portion 4 b is separated from the coil 15.

The end of the first electrode layer 21 included in the electrode portion 5b is located closer to the end face 2b than the position of the maximum thickness T _RSmax of the second electrode layer 23 included in the electrode portion 5b when viewed from the second direction D2. . In this case, as compared with a configuration in which the end of the first electrode layer 21 included in the electrode portion 5b is located farther from the end face 2b than the position of the maximum thickness T _RSmax of the second electrode layer 23 included in the electrode portion 5b. As a result, the end of the first electrode layer 21 included in the electrode portion 5 b is separated from the coil 15.

  As described above, since the end of the first electrode layer 21 included in the electrode portions 4b and 5b is separated from the coil 15, the end of the first electrode layer 21 included in the electrode portions 4b and 5b serves as a starting point. However, even if a crack occurs in the coil 15, it is difficult for the crack to occur to reach the coil 15. Therefore, even when a crack occurs in the element body 2, the crack hardly affects the coil 15, and deterioration of the electrical characteristics of the laminated coil component 1 is suppressed.

  Although the embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments, and various changes can be made without departing from the gist of the present invention.

  In the above embodiment, an example in which the external electrodes 4 and 5 include the electrode portions 4a and 5a, the electrode portions 4b and 5b, and the electrode portions 4c and 5c has been described as an example. However, the shape of the external electrode is not limited to this. For example, external electrode 4 may be formed only on end surface 2a and one main surface 2c, and external electrode 5 may be formed only on end surface 2b and one main surface 2c. In this case, the main surface 2c is a mounting surface.

The thickness T _RS1 of the second electrode layer 23 located on the end of the first electrode layer 21 included in the electrode portions 4b and 5b is 50% of the maximum thickness T _RSmax of the second electrode layer 23 included in the electrode portions 4b and 5b. If so, the lengths L _SE1 and L _SE2 may be longer than the lengths L _RS1 and L _RS2 . It is preferable that the lengths L _SE1 and L _SE2 are smaller than the lengths L _RS1 and L _RS2 from the viewpoint of suppressing the deterioration of the electrical characteristics of the laminated coil component 1 described above.

The thickness T _RS1 may be less than 50% of the maximum thickness T _RSmax . From the viewpoint of suppressing a reduction in the stress relaxation effect of the laminated coil component 1 described above, the thickness T _RS1 is preferably _equal to or more than 50% of the maximum thickness T _RSmax .

  As viewed from the first direction D1, the position where the other ends of the connection conductors 17 and 18 on the end surfaces 2b and 2a are exposed and the position of the maximum thickness of the second electrode layer 23 included in the electrode portions 4a and 5a overlap. You may. In order to make it difficult to obtain a laminated coil component 1 having a high DC resistance, as described above, the position where the other ends of the connection conductors 17 and 18 on the end faces 2b and 2a are exposed and the position where the electrode portions 4a and 5a include Preferably, the position of the maximum thickness of the two-electrode layer 23 is different.

  DESCRIPTION OF SYMBOLS 1 ... Laminated coil component, 2 ... element body, 2a, 2b ... End surface, 2c, 2d ... Main surface, 4,5 ... External electrode, 15 ... Coil, 16a-16f ... Coil conductor, 17, 18 ... Connection conductor, 21 ... first electrode layer, 23 ... second electrode layer.

Claims (5)

Prime field,
A coil arranged in the body,
An external electrode disposed on the surface of the element body and electrically connected to the coil;
The prime field is
The main surface, which is the mounting surface,
Having an end face located adjacent to the main surface and extending in a direction intersecting with the main surface,
The external electrode,
A base metal layer formed on the main surface and the end surface,
A conductive resin layer formed so as to cover the base metal layer,
An end of the base metal layer located on the main surface is located outside the coil when viewed from a direction orthogonal to the main surface ,
A laminated coil component , wherein an end of the conductive resin layer located on the main surface overlaps with the coil when viewed from a direction orthogonal to the main surface .   2. The laminated coil according to claim 1, wherein a thickness of the conductive resin layer at the end of the base metal layer is 50% or more of a maximum thickness of a portion of the conductive resin layer located on the main surface. 3. parts.   With the surface including the end surface as a reference surface, the end surface with respect to the length from the reference surface in a direction orthogonal to the end surface to the position of the maximum thickness in the portion located on the main surface of the conductive resin layer. 3. The laminated coil component according to claim 2, wherein a ratio of a length from the reference plane to the end of the base metal layer in a direction perpendicular to the direction is 0.6 to 1.0. 4. Further comprising a conductor disposed in the body, having one end connected to the coil, and the other end exposed to the end face and connected to the base metal layer,
When viewed from a direction perpendicular to the end face, a position where the other end of the conductor is exposed on the end face and a position of a maximum thickness in a portion of the conductive resin layer located on the end face are different. The laminated coil component according to any one of claims 1 to 3.   The end portion of the base metal layer is located closer to the end surface than a position of a maximum thickness in a portion of the conductive resin layer located on the main surface when viewed from a direction orthogonal to the main surface. The laminated coil component according to any one of claims 1 to 4.

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