This application is based on and claims the benefit of priority from Japanese Patent Application Serial No. 2019-158107 (filed on Aug. 30, 2019), the contents of which are hereby incorporated by reference in their entirety.
The present invention relates to a coil component.
Various coil components have been known. One of well-known coil components is an inductor. An inductor is a passive element used in an electronic circuit. For example, an inductor eliminates noise in a power source line or a signal line. A conventional coil component includes a main body formed of a magnetic material, a coil conductor disposed in the main body, and a plurality of external electrodes disposed on the surface of the main body. The plurality of external electrodes are connected to each other via the coil conductor and lead-out conductors. The main body of the coil component is formed of ferrite, a composite resin material containing soft magnetic metal particles, or any other known magnetic material. Conventional coil components are disclosed in, for example, International Publication No. WO 2011/155241 and Japanese Patent Application Publication No. 2015-039026.
In a conventional coil component, an external electrode may fall off the main body if the joint strength between the base body and the external electrode is insufficient. For example, the external electrodes may fall off the main body when the coil component is being mounted on a circuit board. In addition, the external electrode may fall off the main body due to the impact imparted when the coil component is dropped.
Currently noted magnetic materials for the main body of the coil component are composite magnetic materials containing soft magnetic metal particles. Since such composite magnetic materials have a higher density than ferrite, a coil component with a main body containing soft magnetic metal particles tend to have a larger weight. The larger weight of the coil component produces a larger force imparted on the external electrodes when the coil component is mounted or dropped, causing the external electrodes to fall off the main body.
An object of the present invention is to solve or relieve at least a part of the above problem. In particular, an object of the present invention is to inhibit the external electrodes from falling off the main body of the coil component. Other objects of the present invention will be apparent with reference to the entire description in this specification.
A coil component according to one embodiment of the present invention comprises: a base body having a plurality of magnetic layers including a first magnetic layer, a second magnetic layer, and a third magnetic layer; a first external electrode provided on a surface of the base body; a second external electrode provided on the surface of the base body, the second external electrode being spaced from the first external electrode; a coil conductor provided in the base body; a first lead-out conductor including a first lead-out conductor first pattern and a first lead-out conductor second pattern; and a second lead-out conductor connecting a second end of the coil conductor and the second external electrode. The first lead-out conductor first pattern is provided between the first magnetic layer and the second magnetic layer so as to be connected to a first end of the coil conductor and the first external electrode. The first lead-out conductor second pattern is provided between the second magnetic layer and the third magnetic layer so as to be connected to the first lead-out conductor first pattern and the first external electrode. In the embodiment, the first magnetic layer, the second magnetic layer, and the third magnetic layer project from a first contact surface and a second contact surface toward an outside of the base body, the first contact surface being a surface at which the first external electrode and the first lead-out conductor first pattern contact with each other, the second contact surface being a surface at which the first external electrode and the first lead-out conductor second pattern contact with each other.
In one embodiment of the present invention, the plurality of magnetic layers further include a fourth magnetic layer, a fifth magnetic layer, and a sixth magnetic layer. In one embodiment of the present invention, the second lead-out conductor includes a second lead-out conductor first pattern and a second lead-out conductor second pattern, the second lead-out conductor first pattern being provided between the fourth magnetic layer and the fifth magnetic layer so as to be connected to the second end of the coil conductor and the second external electrode, the second lead-out conductor second pattern being provided between the fifth magnetic layer and the sixth magnetic layer so as to be connected to the second lead-out conductor first pattern and the second external electrode. In one embodiment of the present invention, the fourth magnetic layer, the fifth magnetic layer, and the sixth magnetic layer project from a third contact surface and a fourth contact surface toward the outside of the base body, the third contact surface being a surface at which the second external electrode and the second lead-out conductor first pattern contact with each other, the fourth contact surface being a surface at which the second external electrode and the second lead-out conductor second pattern contact with each other.
In one embodiment of the present invention, the surface of the base body includes a first region and a second region, the first region being a region in which the first lead-out conductor is exposed, the second region projecting from the first region toward the outside of the base body. In one embodiment of the present invention, the first external electrode covers at least a part of the first region. In one embodiment of the present invention, the first external electrode is provided on the surface so as to cover at least a part of the first region and at least a part of the second region.
In one embodiment of the present invention, the first external electrode and the second external electrode are connected to a circuit board, In one embodiment of the present invention, the surface of the base body includes a mounting surface facing the circuit board, and the first region and the second region are regions in the mounting surface.
In one embodiment of the present invention, the first external electrode and the second external electrode are connected to a circuit board, In one embodiment of the present invention, the surface of the base body includes a first end surface and a second end surface both connected to the mounting surface facing the circuit board, the first end surface includes a third region in which the first lead-out conductor is exposed, and the second end surface includes a fourth region in which the second lead-out conductor is exposed. In one embodiment of the present invention, the first external electrode is provided on the surface so as to further cover at least a part of the third region, and the second external electrode is provided on the surface so as to further cover at least a part of the fourth region.
In one embodiment of the present invention, a thickness of each of the first magnetic layer, the second magnetic layer, and the third magnetic layer is smaller than a thickness of the first lead-out conductor first pattern and a thickness of the first lead-out conductor second pattern.
A coil component according to one embodiment of the present invention further comprises: a first independent conductor disposed in the base body so as to be spaced from the coil conductor, the first lead-out conductor, and the second lead-out conductor, the first independent conductor contacting with the first external electrode at a fifth surface, In one embodiment, the first independent conductor is provided on a first independent magnetic layer included in the plurality of magnetic layers, the first independent magnetic layer being different from the first magnetic layer, the second magnetic layer, and the third magnetic layer, and the first independent magnetic layer projects from the fifth contact surface toward the outside of the base body. A coil component according to one embodiment of the present invention further comprises: a second independent conductor disposed in the base body so as to be spaced from the coil conductor, the first lead-out conductor, and the second lead-out conductor, the second independent conductor contacting with the second external electrode at a sixth contact surface, In one embodiment, the second independent conductor is provided on the first independent magnetic layer, and the first independent magnetic layer projects from the sixth contact surface toward the outside of the base body.
An embodiment of the present invention relates to a circuit board comprising any one of the above coil components.
An embodiment of the present invention relates to an electronic device comprising the above circuit board.
In a coil component according to one embodiment of the present invention, the external electrodes can be inhibited from falling off the main body.
A coil component 1 according to one embodiment of the present invention will be hereinafter described with reference to
Each of the drawings shows the L axis, the W axis, and the T axis orthogonal to one another. In this specification, a “length” direction, a “width” direction, and a “thickness” direction of the coil component 1 refer to the direction along the L axis, the direction along the W axis, and the direction along the T axis in
The coil component 1 is mounted on a circuit board 2. The circuit board 2 has two land portions 3 provided thereon. The coil component 1 may be mounted on the circuit board 2 by soldering the external electrodes 21, 22 to the corresponding land portions 3 of the circuit board 2. The circuit board 2 can be installed in various electronic devices. Electronic devices in which the circuit board 2 may be installed include smartphones, tablets, game consoles, and various other electronic devices.
The coil component 1 is an example coil component to which the present invention is applicable. The invention may be applied to inductors, transformers, filters, reactors, and various other coil components. The invention may be also applied to coupled inductors, choke coils, and any other magnetically coupled coil components.
The base body 10 is made of a magnetic material and formed in a rectangular parallelepiped shape. In one embodiment of the invention, the base body 10 has a length (the dimension in the L axis direction) of 1.0 to 10.0 mm, a width (the dimension in the W axis direction) of 0.5 to 10.0 mm, and a thickness (the dimension in the T axis direction) of 0.8 to 5.0 mm. For example, the base body 10 has a length of 3.2 mm, a width of 2.5 mm, and a thickness of 2.5 mm. The dimensions of the base body 10 are not limited to those specified herein. The term “rectangular parallelepiped” or “rectangular parallelepiped shape” used herein is not intended to mean solely “rectangular parallelepiped” in a mathematically strict sense.
The base body 10 has a first principal surface 10a, a second principal surface 10b, a first end surface 10c, a second end surface 10d, a first side surface 10e, and a second side surface 10f. The outer surface of the base body 10 is defined by these six surfaces. The first principal surface 10a and the second principal surface 10b are opposed to each other, the first end surface 10c and the second end surface 10d are opposed to each other, and the first side surface 10e and the second side surface 10f are opposed to each other. Based on the position of the circuit board 2, the first principal surface 10a lies on the top side of the base body 10, and therefore, the first principal surface 10a may be herein referred to as “the top surface.” Similarly, the second principal surface 10b may be referred to as “the bottom surface.” The coil component 1 is disposed such that the second principal surface 10b faces the circuit board 2, and therefore, the second principal surface 10b may be herein referred to as “the mounting surface” or “the mounting surface 10b.” The top-bottom direction of the coil component 1 refers to the top-bottom direction in
In the embodiment shown, the external electrode 21 and the external electrode 22 are provided on the mounting surface 10b of the base body 10. It is also possible that the external electrodes 21 and 22 are provided on a surface of the base body 10 other than the mounting surface 10b.
The base body 10 is made of a magnetic material. The magnetic material for the base body 10 may contain a plurality of soft magnetic metal particles. The soft magnetic metal particles contained in the magnetic material for the base body 10 are, for example, particles of (1) a metal such as Fe or Ni, (2) a crystalline alloy such as an Fe—Si—Cr alloy, an Fe—Si—Al alloy, or an Fe—Ni alloy, (3) an amorphous alloy such as an Fe—Si—Cr—B—C alloy or an Fe—Si—Cr—B alloy, or (4) a mixture thereof. The composition of the soft magnetic metal particles contained in the base body 10 is not limited to those described above. For example, the soft magnetic metal particles contained in the base body 10 may be particles of a Co—Nb—Zr alloy, an Fe—Zr—Cu—B alloy, an Fe—Si—B alloy, an Fe—Co—Zr—Cu—B alloy, an Ni—Si—B alloy, or an Fe—Al—Cr alloy. An insulating film may be provided on a surface of each of the soft magnetic metal particles. The insulating film may be an oxide film made of an oxide of the above metals or alloys. The insulating film provided on the surface of each of the soft magnetic metal particles may be a silicon oxide film provided by the sol-gel coating process. The insulating film provided on the surface of each of the soft magnetic metal particles may contain Bi.
In one embodiment, the soft magnetic metal particles have an average particle size of 1.5 to 20 μm. The average particle size of the soft magnetic metal particles contained in the base body 10 may be smaller than 1.5 μm or larger than 20 μm. The base body 10 may contain two or more types of soft magnetic metal particles having different average particle sizes. For example, the soft magnetic metal particles for the composite magnetic material may include first soft magnetic metal particles having a first average particle size and second soft magnetic metal particles having a second average particle size smaller than the first average particle size. In one embodiment, the base body 10 may further contain third soft magnetic metal particles having a third average particle size smaller than the second average particle size. The average particle size of the soft magnetic metal particles contained in the base body 10 is determined based on the particle size distribution. To determine the particle size distribution, the base body 10 is cut along the thickness direction (T direction) to expose a section, and the section is scanned by a scanning electron microscope (SEM) to take photographs at a 2000 to 5000-fold magnification for particles 1 μm or larger and at a 5000 to 10000-fold magnification for particles smaller than 1 μm, and the particle size distribution is determined based on the photographs. For example, the value at 50 percent of the particle size distribution determined based on the SEM photographs can be set as the average particle size of the soft magnetic metal particles.
The base body 10 may be formed of a composite magnetic material containing the soft magnetic metal particles and a binder. When the base body 10 is formed of the composite magnetic material, the binder included in the composite magnetic material is, for example, a thermosetting resin with excellent insulation properties. Examples of the binder include an epoxy resin, a polyimide resin, a polystyrene (PS) resin, a high-density polyethylene (HDPE) resin, a polyoxymethylene (POM) resin, a polycarbonate (PC) resin, a polyvinylidene fluoride (PVDF) resin, a phenolic resin, a polytetrafluoroethylene (PTFE) resin, or a polybenzoxazole (PBO) resin.
The base body 10 may have two or more regions made of different magnetic materials. For example, the magnetic layer 11a and the magnetic layer 11b may be formed of different magnetic materials from each other.
Next, with further reference to
The magnetic layers 11c to 11f have coil patterns C1 to C4, respectively, disposed on one surface thereof, and the magnetic layers 11b to 11g have lead-out conductor patterns L1a to L1f and lead-out conductor patterns L2a to L2f, respectively, disposed on one surface thereof. In the illustrated embodiment, the magnetic layers 11c to 11f have the coil conductor patterns C1 to C4, and the magnetic layers 11b to 11g have the lead-out conductor patterns L1a to L1f and the lead-out conductor patterns L2a to L2f disposed on the negative side surfaces thereof in the W-axis direction, among the pairs of surfaces thereof intersecting the W-axis direction. The coil conductor patterns C1 to C4, the lead-out conductor patterns L1a to L1f, and the lead-out conductor patterns L2a to I2f are formed by, for example, printing a conductive paste made of a highly conductive metal or alloy via screen printing. The conductive paste may be made of Ag, Pd, Cu, Al, or alloys thereof. The coil conductor patterns C1 to C4 may be formed using other methods and materials. For example, the coil conductor patterns C1 to C4 may be formed by sputtering, ink-jetting, or other known methods.
The magnetic layers 11d to 11f are provided with vias V11 to V13, respectively, at a predetermined position therein, and the magnetic layers 11c to 11g are provided with vias Via to Vie and vias V2a to V2e, respectively, at a predetermined position therein. The vias V11 to V13 are formed by forming a through-hole at the respective predetermined position in the magnetic layers 11d to 11f so as to extend through the magnetic layers 11d to 11f in the W axis direction and filling the through-holes with a conductive paste. The vias Via to Vie and the vias V2a to V2e are formed by forming a through-hole at the respective predetermined position in the magnetic layers 11c to 11g so as to extend through the magnetic layers 11c to 11g in the W axis direction and filling the through-holes with a conductive paste.
Adjacent ones of the coil conductor patterns C1 to C4 are electrically connected to each other through one of the vias V11 to V13. The coil conductor patterns C1 to C4 and the vias V11 to V13 connected together in this manner form the spiral coil conductor 25. In other words, the coil conductor 25 is constituted by the coil conductor patterns C1 to C4 and the vias V11 to V13.
One end of the coil conductor pattern C1 is connected to the via V11, and the other end of the coil conductor pattern C1 is connected to the lead-out conductor pattern L2b. One end of the coil conductor pattern C4 is connected to the via V13, and the other end of the coil conductor pattern C4 is connected to the lead-out conductor pattern Lie. In other words, the coil conductor 25 is connected at one end thereof to the lead-out conductor 23 and at the other end thereof to the lead-out conductor 24. As described above, the lead-out conductor 23 electrically connects between one end of the coil conductor 25 and the external electrode 21, and the lead-out conductor 24 electrically connects between the other end of the coil conductor 25 and the external electrode 22.
Adjacent ones of the lead-out conductor patterns L1a to L1f are electrically connected to each other through one of the vias V1a to Vie, and adjacent ones of the lead-out conductor patterns L2a to L2f are electrically connected to each other through one of the vias V2a to V2e. In this way, the lead-out conductor patterns L1a to L1f and the vias V1a to Vie connected together constitute the lead-out conductor 23, and the lead-out conductor patterns L2a to L2f and the vias V2a to V2e connected together constitute the lead-out conductor 24. In other words, the lead-out conductor 23 includes the lead-out conductor patterns L1a to L1f and the vias V1a to Vie, and the lead-out conductor 24 includes the lead-out conductor patterns L2a to L2f and the vias V2a to V2e.
As shown in
The external electrode 21 covers at least a part of the first exposure region A1. The external electrode 21 may alternatively cover the whole of the first exposure region A1. The external electrode 21 is connected to each of the lead-out conductor patterns L1a to L1f. The external electrode 22 covers at least a part of the second exposure region A2. The external electrode 22 may alternatively cover the whole of the second exposure region A2. The external electrode 22 is connected to a part or all of the lead-out conductor patterns L2a to L2f. In this way, the lead-out conductor patterns L1a to L1f are connected to the external electrode 21, and the lead-out conductor patterns L2a to L2f are connected to the external electrode 22.
Next, a description is given of the first exposure region A1 in the mounting surface 10b with reference to
As clearly shown in
In the embodiment shown, the thickness (the dimension in the W axis direction) of each of the magnetic layers 11b to 11g is smaller than the thickness (the dimension in the W axis direction) of each of the lead-out conductor patterns L1a to L1f. This reduces resistances of the lead-out conductor 23 and the lead-out conductor 24. The thickness of each of the lead-out conductor patterns Lia to L1f may be equal to or larger than two, three, four, five, or ten times as large as the thickness of each of the magnetic layers 11b to 11g.
The lead-out conductor patterns L1a to L1f are disposed such that the respective end surfaces L1a1 to L1f1 thereof are exposed from the mounting surface 10b of the base body 10. In other words, the respective end surfaces L1a1 to L1f1 of the lead-out conductor patterns Lia to L1f are exposed from the mounting surface 10b of the base body 10 to the outside of the base body 10. As will be described later, the respective end surfaces L1a1 to L1f1 of the lead-out conductor patterns Lia to L1f are polished, and therefore, each of the end surfaces L1a1 to L1f1 are concave toward the inside of the base body 10 (in the positive direction of the T axis). As shown in
As shown, the magnetic layers 11a to 11h project from the contact surfaces L1a1 to L1f1 of the lead-out conductor patterns L1a to L1f toward the outside of the base body 10. In the embodiment shown, the magnetic layers 11a to 11h project from the contact surfaces L1a1 to L1f1 in the negative direction of the T axis. The magnetic layers 11b to 11g have respective projections 11b1 to 11g1 projecting from the contact surfaces L1a1 to L1f1 toward the outside of the base body 10. The contact surfaces L1a1 to L1f1 are concaved toward the inside of the base body 10. Therefore, the contact portions of the contact surfaces L1a1 to L1f1 each contacting with adjacent one of the magnetic layers 11a to 11h are at the outermost positions (on the negative side in the T axis direction) within the base body 10. The magnetic layers 11a to 11h project toward the outside of the base body 10 beyond the contact portions of the contact surfaces L1a1 to L1f1 that are at the outermost positions within the base body 10. Although not shown, the relationship between the magnetic layers 11a to 11h and the lead-out conductor patterns L2a to L2f is the same as the relationship between the magnetic layers 11a to 11h and the lead-out conductor patterns L1a to L1f shown in
In one embodiment, the magnetic layers 11a to 11h have a higher wear resistance than the lead-out conductor patterns L1a to L1f. Therefore, the first exposure region A1 can be polished such that the end surfaces L1a1 to L1f1 of the lead-out conductor patterns L1a to L1f are concaved from the magnetic layers 11a to 11h. Likewise, the magnetic layers 11a to 11h have a higher wear resistance than the lead-out conductor patterns L2a to L2f. Therefore, the second exposure region A2 can be polished such that the end surfaces of the lead-out conductor patterns L2a to L2f are concaved from the magnetic layers 11a to 11h. The end surfaces L1a1 to L1f1 of the lead-out conductor patterns L1a to L1f may be curved. For example, each of the end surfaces L1a1 to L1f1 of the lead-out conductor patterns L1a to L1f is curved to be most deeply concaved at the middle in the W axis direction. Since the end surfaces L1a1 to L1f1 are curved, the contact area between the lead-out conductor patterns L1a to L1f and the external electrode 21 is larger. As a result, the external electrode 21 can be mounted on the lead-out conductor 23 more firmly. In each of the curved end surfaces L1a1 to L1f1 of the lead-out conductor patterns L1a to L1f, the dimension between the portion at the outermost position (on the negative side in the T axis direction) and the portion at the innermost position (on the positive side in the T axis direction) is, for example, 2 to 35 μM (this dimension is herein referred to as “amount of concavity”). The amount of concavity of the end surfaces L1a1 to L1f1 may be equal to or larger than one-twelfth, one-eleventh, one-tenth, one-ninth, one-eighth, one-seventh, or one-sixth of the thickness of the lead-out conductor patterns L1a to L1f. The above description on the end surfaces L1a1 to L1f1 of the lead-out conductor patterns L1a to L1f also applies to the end surfaces of the lead-out conductor patterns L2a to L2f.
In one embodiment, the magnetic layers 11a to 11h project, for example, by 3 to 50 μm, from the lead-out conductor patterns L1a to L1f toward the outside of the base body 10. In other words, the amount of projection of the magnetic layers 11a to 11h from the lead-out conductor patterns Lia to L1f is, for example, 3 to 50 μm. The presence of projections 11b1 to 11g1 enlarges the contact area in which the external electrode 21 contacts with the base body 10 and the lead-out conductor 23, thereby inhibiting the external electrode 21 from falling off. The dimension of the projections 11b1 to 11g1 in the T axis direction (this dimension is herein referred to as “amount of projection”) may be equal to or larger than one-tenth, one-ninth, one-eighth, one-seventh, one-sixth, or one-fifth of the thickness (the dimension in the W axis direction) of each of the lead-out conductor patterns L1a to L1E The amount of projection of the magnetic layers 11a to 11h from the lead-out conductor patterns L2a to L2f may be about the same as that of the magnetic layers 11a to 11h from the lead-out conductor patterns L1a to L1f.
As described above, the magnetic layer 11a and the magnetic layer 11h each include a plurality of magnetic layers. The magnetic layer 11a includes a projection 11a1 that projects beyond the projections 11b1 to 11g1 of the magnetic layers 11b to 11g toward the outside of the base body 10, and the magnetic layer 11h includes a projection 11h1 that projects beyond the projections 11b1 to 11g1 of the magnetic layers 11b to 11g toward the outside of the base body 10. The projection 11a1 and the projection 11b1 are disposed in the non-exposure region A3 of the mounting surface 10b. The projection 11a1 and the projection 11h1 project by D1 in the negative direction of the T axis beyond the ends of the projections 11b1 to 11g1 of the magnetic layers 11b to 11g. The amount of projection D1 is within the range of, for example, 10 to 120 μm. The cover layer 11a and the cover layer 11h may be configured such that the amount of projection D1 is larger as the total thickness of the lead-out conductor patterns L1a to L1f is larger.
Since the external electrode 21 is disposed on the first exposure region A1 of the mounting surface 10b, the indentation of the first exposure region A1 is reflected in the outer surface 21a of the external electrode 21, as shown in
In
Next, another embodiment of the invention will be described with reference to
Next, a description is given of an example of a production method of the coil component 1. The coil component 1 can be produced by, for example, a lamination process. An example is hereinafter described of the production method of the coil component 1 using the lamination process.
The first step is to prepare a plurality of magnetic sheets made of a magnetic material. These magnetic sheets will be fired to form the magnetic layers 11a to 11h. The magnetic sheets are made of, for example, a composite magnetic material containing a binder and a plurality of soft magnetic metal particles.
Next, a through-hole is formed in each of the magnetic sheets to be the magnetic layers 11c to 11g at a predetermined position so as to extend through the magnetic sheet in the W axis direction. Next, a conductive paste is printed on the surface of each of the magnetic sheets to be the magnetic layers 11b to 11g, thereby forming unfired conductor patterns to be fired to form the coil conductor patterns C1 to C4, the lead-out conductor patterns Lia to L1f, and the lead-out conductor patterns L2a to L2f. The through-hole formed in each magnetic sheet is filled with the conductive paste. The conductive paste filled in the through-holes will be fired to form the vias V11 to V13, the vias Via to Vie, and the vias V2a to V2e. The unfired conductor patterns to be fired to form the coil conductor patterns C1 to C4 are herein referred to as unfired coil conductor patterns C1 to C4. Likewise, the conductor patterns or the conductive paste filled in the through-holes to be fired to form the lead-out conductor patterns L1a to L1f, the lead-out conductor patterns L2a to L2f, the vias V11 to V13, the vias Via to Vie, and the vias V2a to V2e are also referred to as unfired lead-out conductor patterns Lia to L1f, and so on.
Next, the magnetic sheets to be the magnetic layers 11a to 11h are stacked together to obtain a laminate. These magnetic sheets are stacked together such that the each of the unfired coil conductor patterns C1 to C4 is connected to adjacent ones of the unfired coil conductor patterns through the unfired vias V11 to V13, each of the unfired lead-out conductor patterns L1a to L1f is connected to adjacent ones of the unfired lead-out conductor patterns through the unfired vias Via to Vie, and each of the unfired lead-out conductor patterns L2a to L2f is connected to adjacent ones of the unfired lead-out conductor patterns through the unfired vias V2a to V2e.
Next, the laminate is diced using a cutter such as a dicing machine or a laser processing machine to obtain a chip laminate. Next, the chip laminate is degreased and then fired.
Next, the chip laminate is polished by barrel-polishing or the like. The medium (polishing stone) used in barrel-polishing should have a particle size smaller than the thickness (the dimension in the W axis direction) of the lead-out conductor patterns L1a to L1f and the lead-out conductor patterns L2a to L2f. In one embodiment, the medium used should have a particle size smaller than half of the thickness of the lead-out conductor patterns L1a to L1f and the lead-out conductor patterns L2a to L2f. When the thickness of the lead-out conductor pattern L1a is not uniform, the dimension thereof in the W axis direction at the end surface L1a1 may be taken as the thickness of the lead-out conductor pattern L1a. The same also applies to the lead-out conductor patterns L1b to L1f and the lead-out conductor patterns L2a to L2f. When the lead-out conductor patterns L1a to L1f and the lead-out conductor patterns L2a to L2f have different thicknesses, the medium used should have a particle size smaller than the smallest one of the thicknesses of the lead-out conductor patterns L1a to L1f and the lead-out conductor patterns L2a to L2f. As described above, the magnetic layers 11a to 11h have a higher wear resistance than the lead-out conductor patterns Lia to L1f and the lead-out conductor patterns L2a to L2f. Therefore, since the medium used in barrel-polishing has a particle size smaller than the thickness (the dimension in the W axis direction) of the lead-out conductor patterns L1a to L1f and the lead-out conductor patterns L2a to L2f, the polishing process can be performed such that the end surfaces L1a1 to L1f1 of the lead-out conductor patterns L1a to L1f are concaved from the magnetic layers 11b to 11f, as shown in
Next, the external electrode 21 and the external electrode 22 are formed on the surface of the chip laminate that corresponds to the mounting surface 10b. The external electrode 21 is provided so as to cover the first exposure region A1, and the external electrode 22 is provided so as to cover the second exposure region A2. Each of the external electrode 21 and the external electrode 22 is formed by applying a conductive paste onto the surface of the chip laminate that corresponds to the mounting surface 10b to form a base electrode and forming a plating layer on the surface of the base electrode. The plating layer is constituted by, for example, two layers including a nickel plating layer containing nickel and a tin plating layer containing tin. At least one of a solder barrier layer and a solder wetting layer may be formed on the external electrode 21 and the external electrode 22 as necessary. The coil component 1 is obtained, as described above.
A part of the steps included in the above production method may be omitted as necessary. In the production method of the coil component 1, steps not described explicitly in this specification may be performed as necessary. A part of the steps included in the production method of the coil component 1 may be performed in different order within the purport of the present invention. A part of the steps included in the production method of the coil component 1 may be performed at the same time or in parallel, if possible.
Next, with reference to
As shown in
The lead-out conductor 123 electrically connects between one end of the coil conductor 25 and the external electrode 121, and the lead-out conductor 124 electrically connects between the other end of the coil conductor 25 and the external electrode 122. As shown in
As shown in
The mounting surface 10b of the base body 10 includes a first exposure region A1 in which the lead-out conductor patterns L11a to L11f are exposed, a second exposure region A2 in which the lead-out conductor patterns L12a to L12f are exposed, and a non-exposure region A3 other than the first exposure region A1 and the second exposure region A2. The end surface 10c includes a third exposure region A11 in which the lead-out conductor patterns L11a to L11f are exposed and a non-exposure region A13a other than the third exposure region A11. The end surface 10d includes a fourth exposure region A12 in which the lead-out conductor patterns L12a to L12f are exposed and a non-exposure region A13b other than the fourth exposure region A12. The end of the first exposure region A1 on the negative side in the L axis direction is connected to the end of the third exposure region A11 on the negative side in the T axis direction. The end of the second exposure region A2 on the positive side in the L axis direction is connected to the end of the fourth exposure region A12 on the negative side in the T axis direction.
Next, a description is given of the fourth exposure region A12 in the end surface 10d with reference to
As shown in
As shown in
As shown in
The above description on the arrangement of the magnetic layers 11a to 11h and the lead-out conductor patterns L1a to L1f also applies to the arrangement of the magnetic layers 11a to 11h and the lead-out conductor patterns L11a to L11f and the arrangement of the magnetic layers 11a to 11h and the lead-out conductor patterns L12a to L12f.
Next, a coil component 201 according to another embodiment of the present invention will be described with reference to
As shown in
In the base body 10, the independent conductor pattern L21 and the independent conductor pattern L22 are spaced from the coil conductor 25, the first lead-out conductor 23, and the second lead-out conductor 24. In other words, the independent conductor pattern L21 and the independent conductor pattern L22 are disposed independently of the coil conductor 25, the first lead-out conductor 23, and the second lead-out conductor 24. Any adjacent two of the coil conductor patterns C1 to C4 constituting the coil conductor 25 are connected together through the vias V11 to V13, whereas the independent conductor pattern L21 and the independent conductor pattern L22 are connected to none of the conductor patterns constituting the coil conductor 25, the first lead-out conductor 23, and the second lead-out conductor 24 in the base body 10. When the coil component 201 includes a plurality of magnetic layers 11i, the independent conductor patterns provided on different magnetic layers 11i may be electrically connected to each other.
The end surface L211 of the independent conductor pattern L21 on the negative side in the T axis direction contacts with the external electrode 21. The external electrode 21 contacts directly with the lead-out conductor 23 and is electrically connected to the coil conductor 25 via the lead-out conductor 23, and therefore, the independent conductor pattern L21 is electrically connected to the lead-out conductor 23 and the coil conductor 25 via the external electrode 21, but in the base body 10, the independent conductor pattern L21 is spaced from the coil conductor 25 and the first lead-out conductor 23. Accordingly, the independent conductor pattern L21 is insulated from the coil conductor 25 and the first lead-out conductor 23 in the base body 10.
The end surface L221 of the independent conductor pattern L22 on the negative side in the T axis direction contacts with the external electrode 22. The independent conductor pattern L22 is electrically connected to the lead-out conductor 24 and the coil conductor 25 via the external electrode 22, but in the base body 10, the independent conductor pattern L22 is spaced from the coil conductor 25 and the second lead-out conductor 24. Accordingly, the independent conductor pattern L22 is insulated from the coil conductor 25 and the second lead-out conductor 24 in the base body 10.
In the base body 10, the independent conductor pattern L21 is spaced from the independent conductor pattern L22. Accordingly, the independent conductor pattern L21 is insulated from the independent conductor pattern L22 in the base body 10.
Any one of the independent conductor pattern L21 and the independent conductor pattern L22 can be omitted. In other words, the magnetic layer 11i has at least one of the independent conductor pattern L21 and the independent conductor pattern L22 provided thereon. The magnetic layer 11i may have another independent electrode (not shown), in addition to the independent conductor pattern L21 and the independent conductor pattern L22. Since the magnetic layer 11i has the independent conductor pattern L21 and the independent conductor pattern L22 provided thereon, the magnetic layer 11i may be herein referred to as an independent magnetic layer.
A further description is given of the magnetic layer 11i with reference to
As shown, the independent conductor patterns L21 are disposed between the magnetic layers 11i and the magnetic layer 11h. Any adjacent two of the lead-out conductor patterns L1a to L1f are connected together through the vias V1a to V1e in the base body 10, whereas the independent conductor patterns L21 are connected to none of the lead-out conductor patterns L1a to L1f in the base body 10. The independent conductor patterns L21 are disposed such that the end surfaces L211 thereof are exposed from the first exposure region A1 of the mounting surface 10b of the base body 10. Since the external electrode 21 is disposed on the mounting surface 10b, the external electrode 21 is disposed to contact with the end surfaces L211 of the independent conductor patterns L21. Although not shown, the independent conductor patterns L22 are disposed such that the end surfaces thereof are exposed from the mounting surface 10b in the second exposure region A2 of the mounting surface 10b of the base body 10. The external electrode 22 is disposed on the mounting surface 10b. Therefore, the external electrode 22 is disposed to contact with the end surfaces of the independent conductor patterns L22. In the coil component 201, the region of the mounting surface 10b in which the lead-out conductor patterns L1a to L1f and the independent conductor patterns L21 are exposed is the first exposure region A1, and the region of the mounting surface 10b in which the lead-out conductor patterns L2a to L2f and the independent conductor patterns L22 are exposed is the second exposure region A2.
As shown in
Next, a coil component 301 according to another embodiment of the present invention will be described with reference to
The independent conductor pattern L121 and the independent conductor pattern L122 are different from the independent conductor pattern L21 and the independent conductor pattern L22 in that the independent conductor patterns L121 and L122 are disposed to be exposed also from the end surface 10c for connection with the external electrode 121 and the external electrode 122. The independent conductor pattern L121 is configured and disposed in the same manner as the independent conductor pattern L21 except that it is exposed from the end surface 10c to be connected to the external electrode 121. The independent conductor pattern L122 is configured and disposed in the same manner as the independent conductor pattern L22 except that it is exposed from the end surface 10d and connected to the external electrode 122.
As shown in
Advantageous effects of the above embodiments will now be described. According to one of the embodiments described above, the magnetic layers 11a to 11h project from the lead-out conductor patterns L1a to L1f toward the outside of the base body 10, and therefore, the mounting surface 10b of the base body 10 has indentation in the first exposure region A1. The external electrode 21 is attached to the base body 10 and the lead-out conductor 23 at the indented surface. The indentation in the first exposure region A1 enlarges the contact area in which the external electrode 21 contacts with the base body 10 and the lead-out conductor 23, thereby securing the attachment of the external electrode 21 to the base body 10 and the lead-out conductor 23. This inhibits the external electrode 21 from falling off the base body 10.
According to the above embodiment, the magnetic layers 11a to 11h project from the lead-out conductor patterns L2a to L2f toward the outside of the base body 10, and therefore, the mounting surface 10b of the base body 10 has indentation in the second exposure region A2. The external electrode 22 is attached to the base body 10 and the lead-out conductor 24 at the indented surface. The indentation in the second exposure region A2 enlarges the contact area in which the external electrode 22 contacts with the base body 10 and the lead-out conductor 24, thereby securing the attachment of the external electrode 22 to the base body 10 and the lead-out conductor 24. This inhibits the external electrode 22 from falling off the base body 10.
According to the above embodiment, the mounting surface 10b of the base body 10 includes the first exposure region A1, the second exposure region A2, and the non-exposure region A3, and the non-exposure region A3 projects from the first exposure region A1 and the second exposure region A2 toward the outside of the base body 10. In other words, in the mounting surface 10b, the first exposure region A1 and the second exposure region A2 are concaved from the non-exposure region A3 toward the inside of the base body 10. When the coil component 1 is mounted on the circuit board 2, a larger amount of solder can be received in the first exposure region A1 and the second exposure region A2 than in the case where the mounting surface 10b is flat. This increases the joint strength between the coil component 1 and the circuit board 2.
The above advantageous effects of the coil component 1 can also be produced by the coil component 101.
In the coil component 101 according to one of the embodiments described above, the magnetic layers 11a to 11h project from the lead-out conductor patterns L11a to L11f and the lead-out conductor patterns L12a to L12f toward the outside of the base body 10, and therefore, the end surface 10c of the base body 10 has indentation in the third exposure region A11, and the end surface 10d of the base body 10 has indentation in the fourth exposure region A12. The external electrode 121 is attached to the base body 10 and the lead-out conductor 123 at the indented surface of the third exposure region A11, in addition to the indented surface of the first exposure region A1 of the mounting surface 10b. This arrangement further enlarges the contact area in which the external electrode 121 contacts with the base body 10 and the lead-out conductor 123, thereby further securing the attachment of the external electrode 121 to the base body 10 and the lead-out conductor 123. Likewise, the external electrode 122 is attached to the base body 10 and the lead-out conductor 124 at the indented surface of the fourth exposure region A12, in addition to the indented surface of the second exposure region A2 of the mounting surface 10b. This arrangement further enlarges the contact area in which the external electrode 122 contacts with the base body 10 and the lead-out conductor 124, thereby further securing the attachment of the external electrode 122 to the base body 10 and the lead-out conductor 124.
According to one of the embodiments described above, the independent conductor pattern L21 is disposed between the magnetic layer 11i and the magnetic layer 11h, and both the magnetic layer 11i and the magnetic layer 11h project from the independent conductor pattern L21 toward the outside of the base body 10, thereby increasing the proportion of first exposure region A1 having the indented surface in the mounting surface 10b. This arrangement enlarges the contact area in which the external electrode 21 contacts with the base body 10, the lead-out conductor 23, and the independent conductor pattern L21, thereby further securing the attachment of the external electrode 21 to the base body 10. Likewise, according to the above embodiment, both the magnetic layer 11i and the magnetic layer 11h project from the independent conductor pattern L22 toward the outside of the base body 10, thereby increasing the proportion of the second exposure region A2 in the mounting surface 10b. This arrangement further secures the attachment of the external electrode 22 to the base body 10.
According to one of the embodiments described above, the independent conductor pattern L121 is disposed between the magnetic layer 11i and the magnetic layer 11h, and both the magnetic layer 11i and the magnetic layer 11h project from the independent conductor pattern L121 toward the outside of the base body 10, thereby increasing the proportion of the third exposure region A11 having the indented surface in the end surface 10c. This arrangement enlarges the contact area in which the external electrode 121 contacts with the base body 10, the lead-out conductor 123, and the independent conductor pattern L121, thereby further securing the attachment of the external electrode 121 to the base body 10. Likewise, according to the above embodiment, both the magnetic layer 11i and the magnetic layer 11h project from the independent conductor pattern L122 toward the outside of the base body 10, thereby increasing the proportion of the fourth exposure region A12 in the end surface 10d. This arrangement further secures the attachment of the external electrode 122 to the base body 10.
In one embodiment, the dimension of the independent conductor pattern L21 in the L axis direction parallel to the external electrode 21 is larger than the dimension thereof in the T axis direction perpendicular to the external electrode 21. As the dimension of the independent conductor pattern L21 in the T axis direction is larger, more interference occurs in the magnetic path of the magnetic flux passing through the base body 10. On the other hand, a larger dimension of the independent conductor pattern L21 in the T axis direction does not increase the fixing strength of the external electrode 21. In view of the above, when the dimension of the independent conductor pattern L21 in the L axis direction parallel to the external electrode 21 is larger than the dimension thereof in the T axis direction perpendicular to the external electrode 21, the external electrode 21 can be fixed firmly with no major impact on the magnetic characteristics of the coil component 1.
The dimensions, materials, and arrangements of the constituent elements described herein are not limited to those explicitly described for the embodiments, and these constituent elements can be modified to have any dimensions, materials, and arrangements within the scope of the present invention. Furthermore, constituent elements not explicitly described herein can also be added to the described embodiments, and it is also possible to omit some of the constituent elements described for the embodiments.
For example, the shapes and the arrangements of the external electrodes 21, 22, 121, and 122 are mere examples. The external electrodes 21, 22, 121, and 122 can be modified as appropriate. For example, at least one of the external electrodes 21, 22, 121, and 122 may contact with at least one of the first side surface 10e, the second side surface 10f, and the first principal surface 10a of the base body 10. When contacting with any one of the first side surface 10e, the second side surface 10f, and the first principal surface 10a, the external electrodes 21, 22, 121, and 122 can be attached to the base body 10 more firmly.
Number | Date | Country | Kind |
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2019-158107 | Aug 2019 | JP | national |