This application is based on and claims the benefit of priority from Japanese Patent Application Serial No. 2022-088102 (filed on May 30, 2022), the contents of which are hereby incorporated by reference in their entirety.
The present disclosure relates mainly to a coil component.
Coil components are passive elements used in electronic devices. For example, coil components are used to eliminate noise in power source lines or signal lines. Coil components are constituted by a base body made of a magnetic material, a coil conductor provided in the base body, and a pair of external electrodes connected to one end and the other end of the coil conductor. The coil conductor includes a winding portion extending along a circumferential direction around a coil axis, and lead-out portions that connect both ends of the winding portion to corresponding external electrodes.
One example of the conventional coil components is disclosed in Japanese Patent Application Publication No. 2011-009391 (“the '391 Publication”). In the coil component described in the '391 Publication, the lead-out portions extending in parallel with the coil axis connect between the winding portion and the external electrodes located on the bottom surface of the base body.
As disclosed in the '391 Publication, coil components are designed such that the winding portion has a large diameter in order to obtain a large inductance. When the external electrodes are located on the bottom surface of the base body, a larger diameter of the winding portion results in a smaller distance between the lead-out portions and the side surfaces or the end surfaces of the base body. Therefore, conventional coil components have a large magnetic resistance around the lead-out portions, and this large magnetic resistance around the lead-out portions deteriorates the magnetic characteristics of the coil components. In addition, magnetic saturation tends to occur in the narrow regions between the lead-out portions and the side surfaces or the end surfaces of the base body. Therefore, the small distance between the lead-out portions and the side surfaces or the end surfaces of the base body can also deteriorate the DC superposition characteristics of the coil component.
Coil components used in high-frequency circuits include a winding portion having a small number of turns (e.g., 1.5 to 2.5 turns). With a smaller number of turns of the winding portion, the length of the lead-out portions is larger relative to the entire length of the coil conductor. Therefore, for coil components including a winding portion having a small number of turns, the shape and arrangement of the lead-out portions have a large effect on the magnetic characteristics and the DC superposition characteristics of the coil component.
One object of the present disclosure is to provide a coil component having improved characteristics obtained by improved lead-out portions.
Other objects of the disclosure will be made apparent through the entire description in the specification. The invention disclosed herein may also address drawbacks other than that grasped from the above description.
A coil component according to one embodiment comprises: a base body made of a magnetic material and having a mounting surface; a first external electrode provided on the mounting surface; a second external electrode provided on the mounting surface, the second external electrode being spaced apart from the first external electrode; and a coil conductor including a winding portion provided in the base body and extending in a circumferential direction around a coil axis, a first lead-out portion connecting between one end of the winding portion and the first external electrode, and a second lead-out portion connecting between another end of the winding portion and the second external electrode. In one embodiment, the first lead-out portion includes a first top-side shaft portion extending from one end of the winding portion along the coil axis, a first bottom-side shaft portion located closer to the coil axis than the first top-side shaft portion and extending from the first external electrode along the coil axis, and a first connection portion connecting between the first top-side shaft portion and the first bottom-side shaft portion.
According to one embodiment of the present disclosure, the characteristics of the coil component can be improved with improved lead-out portions.
Various embodiments of the present invention will be described hereinafter with reference to the appended drawings. Throughout the drawings, the same components common in the drawings are denoted by the same reference numerals. For convenience of explanation, the drawings are not necessarily drawn to scale. The following embodiments of the present invention do not limit the scope of the claims. The elements included in the following embodiments are not necessarily essential to solve the problem addressed by the invention.
Attempts have conventionally been made to improve the magnetic characteristics and the DC superposition characteristics of coil components, mainly by improving the shape and arrangement of the winding portion. By contrast, the Inventor of the present application has focused on the fact that, in coil components including a coil conductor having a winding portion with a small number of turns, the lead-out portions greatly affect the characteristics of the coil component, and has found that the magnetic characteristics and the DC superposition characteristics of the coil component can be improved through improvement of the lead-out portions. The following description provides an overview of the coil component 1 with reference to
As shown, the coil component 1 includes a base body 10, a coil conductor provided in the base body 10, a first external electrode 21 disposed on a surface of the base body 10, and a second external electrode 22 disposed on the surface of the base body 10 at a position spaced apart from the first external electrode 21. The first external electrode 21 is electrically connected to one end of the coil conductor 25, and the second external electrode 22 is electrically connected to the other end of the coil conductor 25.
The coil conductor 25 includes a winding portion 25a, a first lead-out portion 25b1, and a second lead-out portion 25b2. The first lead-out portion 25b1 connects between one end of the winding portion 25a and the first external electrode 21. The second lead-out portion 25b2 connects between the other end of the winding portion 25a and the second external electrode 22.
The surface of the coil conductor 25 may be covered by an insulating film (not shown) composed of insulating material having a good insulation property. The insulating film may be an oxide film formed on the surface of the coil conductor 25 during the heat treatment in the manufacturing process of the coil component 1. The insulating film may be a coating film composed of resin having a good insulation property, such as polyurethane, polyamide imide, polyimide, polyester, polyester imide.
The coil component 1 may be mounted on a mounting substrate 2a. The mounting substrate 2a has lands 3a and 3b provided thereon. The coil component 1 is mounted on the mounting substrate 2a by bonding the first external electrode 21 to the land 3a and bonding the second external electrode 22 to the land 3b. A circuit board 2 according to one embodiment of the present invention includes the coil component 1 and the mounting substrate 2a having the coil component 1 mounted thereon. The circuit board 2 can be installed in various electronic devices. The electronic devices in which the circuit board 2 can be installed include smartphones, tablets, game consoles, electrical components of automobiles, servers, and various other electronic devices.
The coil component 1 may be an inductor, a transformer, a filter, a reactor, an inductor array and any one of various other coil components. The coil component 1 may alternatively be a coupled inductor, a choke coil, and any one of various other magnetically coupled coil components. Applications of the coil component 1 are not limited to those explicitly described herein.
In one embodiment, the base body 10 is formed of a magnetic material into a rectangular parallelepiped shape. For example, the coil component 1 has a dimension in the L axis direction (length) of 0.5 mm to 6.0 mm, a dimension in the W axis direction (width) of 0.3 mm to 4.5 mm, and a dimension in the T axis direction (height) of 0.3 mm to 4.5 mm. In one embodiment, the length of the coil component 1 may be larger than the width thereof. The term “rectangular parallelepiped” or “rectangular parallelepiped shape” used herein is not intended to mean solely “rectangular parallelepiped” in a mathematically strict sense. As described later, the corners and/or edges of the base body 10 may be rounded. The dimensions and the shape of the base body 10 are not limited to those specified herein.
In the coil component 1, the first lead-out portion 25b1 and/or the second lead-out portion 25b2 of the coil conductor 25 is improved to improve the magnetic characteristics and the DC superposition characteristics, and therefore, the improved magnetic characteristics and DC superposition characteristics can be obtained without increasing the diameter of the winding portion 25a. Therefore, the external dimensions of the coil component 1 required to obtain a given inductance can be smaller than those of conventional coil components. In one embodiment, the largest of the length, width, and height of the coil component 1 may be 2.0 mm or less. In the illustrated embodiment, the length and the width of the coil component 1 correspond to the length and the width of the base body 10, respectively. The largest of the length, width, and height of the coil component 1 may be 1.5 mm or less or may be 1.0 mm or less. The volume of the coil component 1 may be 2.0 mm 3 or less, 1.5 mm 3 or less, or 1.0 mm 3 or less.
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. Each of the first end surface 10c, the second end surface 10d, the first side surface 10e, and the second side surface 10f is connected to the second principal surface 10b. The first end surface 10c connects between the first side surface 10e and the second side surface 10f. The second end surface 10d also connects between the first side surface 10e and the second side surface 10f. The corners and/or edges of the base body 10 may be rounded. When the edges of the base body 10 are rounded, any two of the first principal surface 10a, the second principal surface 10b, the first end surface 10c, the second end surface 10d, the first side surface 10e, and the second side surface 10f adjacent to each other are connected via a rounded surface. Thus, each of the first end surface 10c, the second end surface 10d, the first side surface 10e, and the second side surface 10f is connected to the second principal surface 10b directly or indirectly via a rounded surface. When the edges of the base body 10 are rounded, the outer surface of the base body 10 is defined by the first principal surface 10a, the second principal surface 10b, the first end surface 10c, the second end surface 10d, the first side surface 10e, the second side surface and the rounded surfaces connecting between any two of these surfaces adjacent to each other.
The first principal surface 10a and the second principal surface 10b are at the opposite ends in the height direction of the base body 10, the first end surface 10c and the second end surface 10d are at the opposite ends in the length direction of the base body and the first side surface 10e and the second side surface 10f are at the opposite ends in the width direction of the base body 10. As shown in
The base body 10 is made of a magnetic material. The magnetic material for use in the base body 10 may be a soft magnetic alloy material, a composite magnetic material including magnetic particles dispersed in a resin, a ferrite material, or any other known magnetic materials.
The soft magnetic metal particles contained in the magnetic material for use in the base body 10 may include at least one of the elements Fe, Ni, and Co as a main component and at least one of the elements Si, Cr, Al, B, and P as an additive. The soft magnetic metal particles contained in the magnetic material for the base body 10 are, for example, particles of a crystalline alloy such as an Fe—Si—Cr alloy, an Fe—Si—Al alloy, or an Fe—Ni alloy, an amorphous alloy such as an Fe—Si—Cr—B—C alloy or an Fe—Si—Cr—B alloy, or 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 contained in the base body 10. The insulating films may be oxide films formed by oxidation of the elements included in the soft magnetic metal particles contained in the magnetic material.
In one or more embodiments, the average particle size of the soft magnetic metal particles contained in the base body 10 is, for example, from 1 μm to 40 μm. The base body 10 may contain two or more types of soft magnetic metal particles having different average particle sizes. The soft magnetic metal particles contained in the base body 10 may include, in addition to first soft magnetic metal particles having an average particle size of 1 μm to 40 μm, second soft magnetic metal particles having an average particle size smaller than that of the first soft magnetic metal particles. The average particle size of the second soft magnetic metal particles is, for example, 0.1 μm to 0.5 μm. Two or more types of soft magnetic metal particles having different average particle sizes are contained in the base body 10 to increase the filling factor of the soft magnetic metal particles in the magnetic base body. The volume proportion of the soft magnetic metal particles in the entire volume of the base body 10 may be 85 vol % or more, or 88 vol % or more. The magnetic characteristics of the base body 10 can be enhanced by raising the filling factor of the soft magnetic metal particles in the base body 10. The mechanical strength of the base body 10 can also be increased by raising the filling factor of the soft magnetic metal particles in the base body 10. The average particle size of the soft magnetic metal particles contained in the base body 10 is determined in the following manner. The base body 10 is cut along the thickness direction (the T axis direction) to expose a section. The section is photographed using a scanning electron microscope (SEM) to obtain a SEM image, and the volume-weighted particle size distribution is determined based on the SEM image. The particle size distribution is used to determine the average particle size. For example, the average particle size (the median diameter (D50)) calculated based on the volume-weighted particle size distribution obtained based on the SEM image can be used as the average particle size of the soft magnetic metal particles contained in the base body 10. The particle size of the first soft magnetic metal particles may be distributed in the range of 1 to 60 μm. The particle size of the second soft magnetic metal particles may be distributed in the range of 0.01 to 1 μm.
In the base body 10, the soft magnetic metal particles may be bonded to each other with an oxide film formed by oxidation of an element included in the soft magnetic metal particles during a manufacturing process. The base body 10 may contain a binder in addition to the soft magnetic metal particles. When the base body 10 contains a binder, the soft magnetic metal particles may be bonded to each other by the binder. The binder in the base body 10 may be formed, for example, by curing a thermosetting resin that has an excellent insulation property. Examples of a material for such a 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 binder contained in the base body 10 is not limited to those described above. For example, the binder contained in the base body 10 may be glass.
As shown in
Although the magnetic film 11 is illustrated as a single-layer sheet-like member, the magnetic film 11 may be a laminate of a plurality of sheet-like members. Likewise, each of the magnetic films 12 to 15 may be a laminate of a plurality of sheet-like members. The thickness of each of the magnetic films 11 to 15 can be adjusted by adjusting the number of sheets that make up the magnetic films 11 to 15.
Next, with further reference to
As shown in
The magnetic film 11 has a through hole extending therethrough in the T axis direction at the region overlapping with one end of the first conductor pattern C11, and a via conductor Vila is embedded in this through hole. The magnetic film 11 also has a through hole extending therethrough in the T axis direction at the region overlapping with the other end of the first conductor pattern C11, and a via conductor V21 is embedded in this through hole.
As shown in
The magnetic film 12 has a through hole extending therethrough in the T axis direction at the region overlapping with the via conductor Vila in plan view, and a via conductor V11b is embedded in this through hole. The via conductor V11b is connected to the via conductor Vila.
As shown in
One end of the second connection portion C22 is connected to the via conductor V31. The magnetic film 13 has a through hole extending therethrough in the T axis direction at the region overlapping with the other end of the second connection portion C22, and a via conductor V32a is embedded in this through hole. The other end of the second connection portion C22 is connected to the via conductor V32a. Thus, on the top-side surface of the magnetic film 13, the second connection portion C22 extends from one end thereof connected to the via conductor V31 to the other end thereof connected to the via conductor V32a.
The first connection portion C21 may extend straight along the LW plane. The straight shape of the first connection portion C21 can inhibit the increase of DC resistance Rdc due to the first connection portion C21. Likewise, the second connection portion C22 may also extend straight along the LW plane. The straight shape of the second connection portion C22 can inhibit the increase of DC resistance Rdc due to the second connection portion C22.
As shown in
As described above, the first conductor pattern C11 and the second conductor pattern C12 are connected by the via conductor V21. The first conductor pattern C11, the via conductor V21, and the second conductor pattern C12 connected in this manner constitute a winding portion 25a having a spiral shape and extending for 1.5 turns around the coil axis Ax in the base body 10. When the coil component 1 is viewed in plan view (from the T axis direction), a part of the winding portion 25a extends for one or more turns along a closed loop path CL having an elliptical shape. The closed loop path CL refers to the region between the inner peripheral surface CL1 having an elliptical shape and the outer peripheral surface CL2 having an elliptical shape with a diameter larger than that of the inner peripheral surface CL1. Since the via conductor Vila is located near the upper left corner of the magnetic film 11, a part of the winding portion 25a diverges from the closed loop path CL and extends toward the via conductor Vila. The shape of the closed loop path CL is not limited to an elliptical shape. The shape of the closed loop path CL in plan view may be an oval, circle, rectangle, polygon, or any other shape.
The region of the base body 10 located inside the closed loop path CL in plan view is referred to as the inner region R1, and the region of the base body 10 located outside the closed loop path CL in plan view is referred to as the outer region R2.
In one embodiment, the number of turns of the winding portion 25a is 3 or less. For example, the number of turns of the winding portion 25a ranges from 1.3 to 2.5. With a smaller number of turns of the winding portion 25a, the lengths of the first lead-out portion 25b1 and the second lead-out portion 25b2 are larger relative to the entire length of the coil conductor 25. In particular, when the number of turns of the winding portion is 3 or less, the lengths of the first lead-out portion 25b1 and the second lead-out portion 25b2 account for a large proportion of the entire length of the coil conductor 25, and thus the shape and arrangement of the first lead-out portion 25b1 and the second lead-out portion 25b2 have a large effect on the characteristics of the coil component 1. The shape and arrangement of the first lead-out portion 25b1 and the second lead-out portion in the coil component 1 are improved such that the coil component 1 has excellent magnetic characteristics and DC superposition characteristics, as described below.
One end of the winding portion 25a is connected to the first external electrode 21 via the via conductor Vila, the via conductor V11b, the first connection portion C21, the via conductor V12a, and the via conductor V12b. Thus, the first lead-out portion 25b1 is constituted by the via conductor Vila, the via conductor V11b, the first connection portion C21, the via conductor V12a, and the via conductor V12b. The via conductors Vila and V11b are located on the same axis extending parallel to the T axis, and thus the via conductors Vila and V11b are collectively referred to as the first top-side shaft portion V11. The first top-side shaft portion V11 is constituted by the via conductor Vila and the via conductor V11b. The via conductors V12a and V12b are located on the same axis extending parallel to the T-axis and are positioned lower (closer to the mounting surface 10b) than the first top-side shaft portion V11, and thus the via conductors V12a and V12b are collectively referred to as the first bottom-side shaft portion V12. The first bottom-side shaft portion V12 is constituted by the via conductor V12a and the via conductor V12b. As described above, one end of the winding portion 25a is connected to the first external electrode 21 via the first lead-out portion 25b1, which is constituted by the first top-side shaft portion V11, the first connection portion C21, and the first bottom-side shaft portion V12. When top-side and bottom-side positions of the coil component 1 or its components are herein referred to, unless they should be interpreted otherwise, the direction closer to the mounting substrate 2a is the “bottom side,” and the direction farther from the mounting substrate 2a is the “top side,” in the attitude in which the coil component 1 is mounted on the mounting substrate 2a. Since the first top-side shaft portion V11 is located farther from the mounting substrate 2a than the first bottom-side shaft portion V12, the first top-side shaft portion V11 is located on the “top side” of the first bottom-side shaft portion V12. Using the coordinate axes shown in
The other end of the winding portion 25a is connected to the second external electrode 22 via the via conductor V31, the second connection portion C22, the via conductor V32a, and the via conductor V32b. Thus, the second lead-out portion 25b2 is constituted by the via conductor V31, the second connection portion C22, the via conductor V32a, and the via conductor V32b. The via conductors V32a and V32b are located on the same axis extending parallel to the T axis, and thus the via conductors V32a and V32b are collectively referred to as the second bottom-side shaft portion V32. The second bottom-side shaft portion V32 is constituted by the via conductor V32a and the via conductor V32b. The via conductor V31, which extends in the T axis direction and is located higher (farther from the mounting surface 10b) than the second bottom-side shaft portion V32, may be referred to as the second top-side shaft portion V31. As described above, the other end of the winding portion 25a is connected to the second external electrode 22 via the second lead-out portion 25b2, which is constituted by the second top-side shaft portion V31, the second connection portion C22, and the second bottom-side shaft portion V32.
With further reference to
The arrangement of the first top-side shaft portion V11 and the first bottom-side shaft portion V12 may be defined with respect to the distances from the first top-side shaft portion V11 and the first bottom-side shaft portion V12 to the first end surface 10c and the first side surface 10e, instead of the distances to the coil axis Ax. As shown in
As can be seen from the plan view of
As shown in
As described above, in the front view, the first bottom-side shaft portion V12 is located closer to the coil axis Ax than the first top-side shaft portion V11, and thus as shown in
As described above, in one embodiment, the first bottom-side shaft portion V12 may be positioned such that the distance L2 between the first bottom-side shaft portion V12 and the first end surface 10c is larger than the distance L1 between the first top-side shaft portion V11 and the first end surface 10c, and the distance W2 between the first bottom-side shaft portion V12 and the first side surface 10e is larger than or equal to the distance W1 between the first top-side shaft portion V11 and the first side surface 10e. In this case, a margin region having a larger volume than the region between the lead-out portion and the surface of the base body in conventional coil components can be provided between the first bottom-side shaft portion V12 and the first side surface 10e as well as between the first bottom-side shaft portion V12 and the first end surface 10c, and thus even better magnetic characteristics and DC superposition characteristics can be provided.
Further, as described above, in one embodiment, the first bottom-side shaft portion V12 may be positioned such that the distance L2 between the first bottom-side shaft portion V12 and the first end surface 10c is larger than or equal to the distance L1 between the first top-side shaft portion V11 and the first end surface 10c, and the distance W2 between the first bottom-side shaft portion V12 and the first side surface 10e is larger than the distance W1 between the first top-side shaft portion V11 and the first side surface 10e. In this case, a margin region having a larger volume than the region between the lead-out portion and the surface of the base body in conventional coil components can be provided between the first bottom-side shaft portion V12 and the first side surface 10e as well as between the first bottom-side shaft portion V12 and the first end surface 10c, and thus even better magnetic characteristics and DC superposition characteristics can be provided.
Thus, in the coil component 1, the magnetic characteristics and the DC superposition characteristics are improved by the first bottom-side shaft portion V12, and thus the first top-side shaft portion V11 can be positioned close to the first end surface 10c. In other words, the desired magnetic characteristics and DC superposition characteristics can be easily achieved in the coil component 1 even if the first top-side shaft portion V11 is positioned close to the first end surface 10c. When the base body 10 contains soft magnetic metal particles, dielectric breakdown may occur between the first top-side shaft portion V11 and a conductor pattern in the winding portion 25a other than the conductor pattern directly contacted by the first top-side shaft portion V11 (in the illustrated example, the first conductor pattern C11). By placing the first top-side shaft portion V11 close to the first end surface 10c, a large distance can be provided between the first top-side shaft portion V11 and the conductor pattern (in the illustrated example, the second conductor pattern C12) other than the conductor pattern directly contacted by the first top-side shaft portion V11 among the conductor patterns constituting the winding portion 25a. This can inhibit dielectric breakdown between the first top-side shaft portion V11 and the conductor pattern other than the conductor pattern directly contacted by the first top-side shaft portion V11 among the conductor patterns constituting the winding portion 25a. When the base body 10 contains soft magnetic metal particles, the dielectric breakdown can be significantly inhibited by positioning the first top-side shaft portion V11 close to the first end surface 10c. The first top-side shaft portion V11 may be positioned such that, in plan view, the distance between the first top-side shaft portion V11 and the first end surface 10c is smaller than the distance between the first top-side shaft portion V11 and the conductor pattern (for example, the second conductor pattern C12) other than the conductor pattern directly contacting the first top-side shaft portion V11 among the conductor patterns constituting the winding portion 25a. The distance between the first top-side shaft portion V11 and the first end surface 10c can be the shortest distance between the surface defining the outer periphery of the first top-side shaft portion V11 and the first end surface 10c in plan view. The distance between the first top-side shaft portion V11 and the conductor pattern other than the conductor pattern directly contacting the first top-side shaft portion V11 among the conductor patterns constituting the winding portion 25a may be the shortest distance between the surface defining the outer periphery of the first top-side shaft portion V11 and the outer peripheral surface of the above conductor pattern (for example, the second conductor pattern C12) in plan view.
When the coil component 1 operates, electric current flows through the coil conductor 25, and the temperature of the coil conductor 25 rises. At this time, stresses act from the coil conductor 25 to the base body 10 due to the difference in the linear expansion coefficient between the base body 10 and the coil conductor 25. In conventional coil components, the lead-out portion of the coil conductor extends straight from one end of the winding portion to the external electrode, and thus the stresses acting from the lead-out portion to the base body is biased in a direction perpendicular to the direction of extension of the lead-out portion. These stresses acting in a uniform direction from the lead-out portion to the base body can cause cracking between the lead-out portion and the base body. By contrast, in the coil component 1, the portion of the first lead-out portion 25b1 that extends in the T-axis direction is divided into the first top-side shaft portion V11 and the first bottom-side shaft portion V12, and the first top-side shaft portion V11 and the first bottom-side shaft portion V12 are connected by the first connection portion C21 that extends perpendicular to the T axis. Therefore, when the temperature of the coil conductor rises, stresses act from the coil conductor 25 to the base body 10 in various directions. This inhibits the occurrence of cracking between the first lead-out portion 25b1 and the base body 10.
The coil conductor 25 is formed by heating a conductive paste together with the magnetic sheets, which are precursors of the magnetic films 11 to 14. Since the conductive paste heated has a different linear expansion coefficient than the magnetic sheets, stresses produced by the difference in linear expansion coefficient act from the first lead-out portion 25b1 (or its precursor, the conductive paste) to the base body 10 (or its precursor, the magnetic sheets) even during heating for forming the coil conductor 25. In the coil component 1, the first top-side shaft portion V11 and the first bottom-side shaft portion V12 are connected by the first connection portion C21 extending in a direction perpendicular to the T-axis, and thus the direction of stresses acting from the first lead-out portion 25b1 to the base body 10 during the heating step in the manufacturing process can be varied. This inhibits cracking between the first lead-out portion 25b1 and the base body 10.
When the coil component 1 is mounted on the mounting substrate 2a, the mounting substrate 2a undergoes thermal expansion and contraction, and thus stresses act from the mounting substrate 2a to the base body 10 and the first lead-out portion 25b1. Since the first lead-out portion 25b1 includes the first top-side shaft portion V11 and the first bottom-side shaft portion V12 extending in the direction parallel to the T axis and the first connection portion C21 extending in a direction perpendicular to the T axis, even when stresses act from the mounting substrate 2a to the base body 10 and the first lead-out portion 25b1, cracking between the first lead-out portion 25b1 and the base body 10 can be inhibited.
For the same reason as described for the first lead-out portion 25b1, cracking between the second lead-out portion 25b2 and the base body 10 is also inhibited.
As shown in
In conventional coil components, a larger distance between the lead-out portion and the surface of the base body makes it possible to secure a larger region in the base body penetrated by the magnetic flux generated by the change in the current flowing in the lead-out portion. However, uniformly increasing the distance between the lead-out portion and the surface of the base body leads to a larger size of the coil component. In the coil component 1 according to one embodiment of the invention, the first bottom-side shaft portion V12 is positioned closer to the coil axis Ax than the first top-side shaft portion V11, thereby improving the magnetic characteristics and the DC superposition characteristics of the coil component 1 without increasing the size of the coil component 1. In one embodiment, the first bottom-side shaft portion V12 is positioned to overlap with the winding portion 25a in plan view. Thus, the first bottom-side shaft portion V12 is positioned in the region between the winding portion 25a and the mounting surface 10b in the base body 10, such that the first bottom-side shaft portion V12 can be positioned close to the coil axis Ax without interfering with other portions of the coil conductor 25.
As shown in
In the coil component 1, the first bottom-side shaft portion V12 is positioned farther from the first end surface 10c than the first top-side shaft portion V11, and thus the thickness of the base body 10 near the edge connecting the first end surface and the mounting surface 10b can be larger than in conventional coil components in which the lead-out portion extends at a uniform and narrow interval from the surface of the base body. This improves the mechanical strength of the region in the base body 10 near the edge connecting the first end surface 10c and the mounting surface 10b, where stresses from impacts tend to concentrate.
Assume a first imaginary plane 51 shown in
In one embodiment, the first external electrode 21 may be positioned such that the left end of the first external electrode 21 (the end in the positive direction along the L axis) is aligned with the first imaginary plane S1 as the coil component 1 is viewed from the front. This allows the first external electrode 21 to be firmly attached to the mounting surface 10b.
The first bottom-side shaft portion V12 is positioned inside the first imaginary plane S1 so as not to intersect the first imaginary plane Si. Thus, the first bottom-side shaft portion V12 is exposed to the outside of the base body 10 through the mounting surface 10b formed flat instead of the rounded surface 10g. This configuration allows a larger contact area between the end surface of the first bottom-side shaft portion V12 and the first external electrode 21 provided on the mounting surface 10b, such that electric connection between the first bottom-side shaft portion V12 and the first external electrode 21 can be secured, and firm bonding between the first bottom-side shaft portion V12 and the first external electrode 21 can be achieved.
Assume a second imaginary plane S2 shown in
The shape and arrangement of the coil conductor 25 shown in
In the embodiment shown in
The arrangement of the first top-side shaft portion V11 and the first bottom-side shaft portion V12 is not limited to the above aspects. The first bottom-side shaft portion V12 is configured and arranged such that the smaller of the distance between the first top-side shaft portion V11 and the first end surface 10c and the distance between the first top-side shaft portion V11 and the first side surface 10e is larger than the smaller of the distance between the first bottom-side shaft portion V12 and the first end surface and the distance between the first bottom-side shaft portion V12 and the first side surface 10e. Thus, a margin area for facilitating the passage of magnetic flux can be provided between the first bottom-side shaft portion V12 and at least one of the first end surface 10c and the first side surface 10e, such that the coil component 1 can have better magnetic characteristics and DC superposition characteristics than conventional coil components.
Next, a coil component 101 according to another embodiment will be described with reference to
The coil component 101 is a magnetically coupled coil component with two coil conductors. More specifically, the coil component 101 has a base body 110, a first coil conductor 125 provided in the base body 110, and a second coil conductor 135 provided in the base body 110 at a distance from the first coil conductor 125. The first coil conductor 125 and the second coil conductor 135 are electrically insulated from each other in the base body 10.
The base body 110 is formed of magnetic material, as is the base body 10. The outer surface of the base body 110 is defined by a top surface 110a, a mounting surface 110b, a first end surface 110c, a second end surface 110d, a first side surface 110e, and a second side surface 110f. The corners and/or edges of the base body 110 may be rounded.
On the mounting surface 110b of the base body 110, there are provided a first external electrode 121, a second external electrode 122, a third external electrode 123, and a fourth external electrode 124. The first external electrode 121, the second external electrode 122, the third external electrode 123, and the fourth external electrode 124 are spaced from each other.
The first coil conductor 125 includes a winding portion 125a, a first lead-out portion 125b1, and a second lead-out portion 125b2. The first lead-out portion 125b1 connects between one end of the winding portion 125a and the first external electrode 121. The second lead-out portion 125b2 connects between the other end of the winding portion 125a and the second external electrode 122. The second coil conductor 135 includes a winding portion 135a, a third lead-out portion 135b3, and a fourth lead-out portion 135b4. The third lead-out portion 135b3 connects between one end of the winding portion 135a and the third external electrode 123. The fourth lead-out portion 135b4 connects between the other end of the winding portion 135a and the fourth external electrode 124.
As shown in
In the embodiment shown, the base body 110 is a laminate formed of the magnetic films 111 to 118 stacked together. However, the boundaries between the magnetic films 111 to 118 may not be visible when a section of the base body 110 is observed under SEM. Of these magnetic films, the magnetic films 111, 112, 114, 115, and 116 have a conductor pattern formed on the top-side surface thereof. Specifically, the magnetic film 111 has a first conductor pattern C111 formed on the top-side surface thereof, the magnetic film 112 has a second conductor pattern C112 formed on the top-side surface thereof, the magnetic film 114 has a third conductor pattern C113 formed on the top-side surface thereof, and the magnetic film 115 has a fourth conductor pattern C114 formed on the top-side surface thereof. Each of the first conductor pattern C111 to the fourth conductor pattern C114 extends in the circumferential direction around a coil axis Ax that extends along the T axis direction. The magnetic film 116 has a first connection portion C121, a second connection portion C122, a third connection portion C123, and a fourth connection portion C124 formed on the top-side surface thereof. The connection portions C121 to C124 are conductor patterns for connecting between via conductors. Each of the magnetic films 111 to 117 has through holes formed at predetermined positions to extend through the magnetic film in the T axis direction, and the via conductors are embedded in these through holes. The conductor patters and the via conductors of the coil component 101 are formed as follows: for example, a conductive paste formed of a metal or an alloy having an excellent conductivity is printed by screen printing on magnetic sheets that are precursor of the magnetic films 111 to 117, and the conductive paste printed on the magnetic sheets is heated.
With further reference to
As shown in
The magnetic film 112 has a through hole extending therethrough in the T axis direction at the region overlapping with the via conductor Villa in plan view, and a via conductor V111b is embedded in this through hole. The via conductor V111b is connected to the via conductor Villa.
As shown in
As shown in
The magnetic film 114 has a through hole extending therethrough in the T axis direction at the region overlapping with the via conductor V111c in plan view, and a via conductor V111d is embedded in this through hole. The via conductor V111d is connected to the via conductor V111c. The magnetic film 114 has a through hole extending therethrough in the T axis direction at the region overlapping with the via conductor V131b in plan view, and a via conductor V131c is embedded in this through hole. The via conductor V131c is connected to the via conductor V131b.
As shown in
The magnetic film 115 has a through hole extending therethrough in the T axis direction at the region overlapping with the via conductor V111d in plan view, and a via conductor Ville is embedded in this through hole. The via conductor Ville is connected to the via conductor V111d. The magnetic film 115 has a through hole extending therethrough in the T axis direction at the region overlapping with the via conductor V131c in plan view, and a via conductor V131d is embedded in this through hole. The via conductor V131d is connected to the via conductor V131c. The magnetic film 115 has a through hole extending therethrough in the T axis direction at the region overlapping with the via conductor V141a in plan view, and a via conductor V141b is embedded in this through hole. The via conductor V141b is connected to the via conductor V141a.
As shown in
One end of the second connection portion C122 is connected to the via conductor V131d. The magnetic film 116 has a through hole extending therethrough in the T axis direction at the region overlapping with the other end of the second connection portion C122, and a via conductor V132a is embedded in this through hole. The other end of the second connection portion C122 is connected to the via conductor V132a. Thus, on the top-side surface of the magnetic film 116, the second connection portion C122 extends from one end thereof connected to the via conductor V131d to the other end thereof connected to the via conductor V132a.
One end of the third connection portion C123 is connected to the via conductor V141b. The magnetic film 116 has a through hole extending therethrough in the T axis direction at the region overlapping with the other end of the third connection portion C123, and a via conductor V142a is embedded in this through hole. The other end of the third connection portion C123 is connected to the via conductor V142a. Thus, on the top-side surface of the magnetic film 116, the third connection portion C123 extends from one end thereof connected to the via conductor V141b to the other end thereof connected to the via conductor V142a.
One end of the fourth connection portion C124 is connected to the via conductor V161. The magnetic film 116 has a through hole extending therethrough in the T axis direction at the region overlapping with the other end of the fourth connection portion C124, and a via conductor V162a is embedded in this through hole. The other end of the fourth connection portion C124 is connected to the via conductor V162a. Thus, on the top-side surface of the magnetic film 116, the fourth connection portion C124 extends from one end thereof connected to the via conductor V161 to the other end thereof connected to the via conductor V162a.
At least one of the first to fourth connection portions C121 to C124 may extend straight along the LW plane. The straight shape of the first to fourth connection portions C121 to C124 can inhibit the increase of DC resistance Rdc due to the first to fourth connection portions C121 to C124 having the straight shape. In the embodiment shown, each of the first to fourth connection portions C121 to C124 extends straight along the L axis direction. Each of the first to fourth connection portions C121 to C124 may extend in a direction oblique to the L axis, as the first connection portion C21 shown in
As shown in
As described above, the first conductor pattern C111 and the second conductor pattern C112 are connected by the via conductor V121. The first conductor pattern C111, the via conductor V121, and the second conductor pattern C112 connected in this manner constitute a winding portion 125a having a spiral shape and extending for 1.25 turns around the coil axis Ax in the base body 10. Also, the third conductor pattern C113 and the fourth conductor pattern C114 are connected by the via conductor V151. The third conductor pattern C113, the via conductor V151, and the fourth conductor pattern C114 connected in this manner constitute a winding portion 135a having a spiral shape and extending for 1.25 turns around the coil axis Ax in the base body 10.
One end of the winding portion 125a (one end of the first conductor pattern C111) is connected to the first external electrode 121 via the via conductors Villa to Ville, the first connection portion C121, the via conductor V112a, and the via conductor V112b. The via conductors Villa to Ville are located on the same axis extending parallel to the T axis, and thus these via conductors are collectively referred to as the first top-side shaft portion V111. The first top-side shaft portion V111 is constituted by the via conductors Villa to Ville. The via conductors V112a and V112b are located on the same axis extending parallel to the T-axis and are positioned lower (closer to the mounting surface 110b) than the first top-side shaft portion V111, and thus these via conductors are collectively referred to as the first bottom-side shaft portion V112. The first bottom-side shaft portion V112 is constituted by the via conductor V112a and the via conductor V112b. As described above, one end of the winding portion 125a is connected to the first external electrode 121 via the first lead-out portion 125b1, which is constituted by the first top-side shaft portion V111, the first connection portion C121, and the first bottom-side shaft portion V112.
The other end of the winding portion 125a (one end of the second conductor pattern C112) is connected to the second external electrode 122 via the via conductors V131a to V131d, the second connection portion C122, the via conductor V132a, and the via conductor V132b. The via conductors V131a to V131d are located on the same axis extending parallel to the T axis, and thus these via conductors are collectively referred to as the second top-side shaft portion V131. The second top-side shaft portion V131 is constituted by the via conductors V131a to V131d. The via conductors V132a and V132b are located on the same axis extending parallel to the T-axis and are positioned lower (closer to the mounting surface 110b) than the second top-side shaft portion V131, and thus these via conductors are collectively referred to as the second bottom-side shaft portion V132. The second bottom-side shaft portion V132 is constituted by the via conductor V132a and the via conductor V132b. As described above, the other end of the winding portion 125a is connected to the second external electrode 122 via the second lead-out portion 125b2, which is constituted by the second top-side shaft portion V131, the second connection portion C122, and the second bottom-side shaft portion V132.
One end of the winding portion 135a (one end of the third conductor pattern C113) is connected to the third external electrode 123 via the via conductor V141a, the via conductor V141b, the third connection portion C123, the via conductor V142a, and the via conductor V142b. The via conductors V141a and V141b are located on the same axis extending parallel to the T axis, and thus these via conductors are collectively referred to as the third top-side shaft portion V141. The third top-side shaft portion V141 is constituted by the via conductor V141a and the via conductor V141b. The via conductors V142a and V142b are located on the same axis extending parallel to the T-axis and are positioned lower (closer to the mounting surface 110b) than the third top-side shaft portion V141, and thus these via conductors are collectively referred to as the third bottom-side shaft portion V142. The third bottom-side shaft portion V142 is constituted by the via conductor V142a and the via conductor V142b. As described above, one end of the winding portion 135a is connected to the third external electrode 123 via the third lead-out portion 135b3, which is constituted by the third top-side shaft portion V141, the third connection portion C123, and the third bottom-side shaft portion V142.
The other end of the winding portion 135a (one end of the fourth conductor pattern C114) is connected to the fourth external electrode 124 via the via conductor V161, the fourth connection portion C124, the via conductor V162a, and the via conductor V162b. The via conductors V162a and V162b are located on the same axis extending parallel to the T axis and are positioned lower (closer to the mounting surface 110b) than the via conductor V161, and thus these via conductors are collectively referred to as the fourth bottom-side shaft portion V162. The fourth bottom-side shaft portion V162 is constituted by the via conductor V162a and the via conductor V162b. The via conductor V161, which is located higher than the fourth bottom-side shaft portion V162 and extends in the T axis direction, may be herein referred to as the fourth top-side shaft portion V161. As described above, the other end of the winding portion 135a is connected to the fourth external electrode 124 via the fourth lead-out portion 135b4, which is constituted by the fourth top-side shaft portion V161, the fourth connection portion C124, and the fourth bottom-side shaft portion V162.
For example, the number of turns of the winding portions 125a and 135a ranges from 1.1 to 2.5. When the number of turns of the winding portion 125a is 3 or less, the lengths of the first lead-out portion 125b1 and the second lead-out portion 125b2 account for a large proportion of the entire length of the first coil conductor 125, and thus the shape and arrangement of the first lead-out portion 125b1 and the second lead-out portion 125b2 have a large effect on the characteristics of the coil component 101. Likewise, when the number of turns of the winding portion 135a is 3 or less, the lengths of the third lead-out portion 135b3 and the fourth lead-out portion 135b4 account for a large proportion of the entire length of the second coil conductor 135, and thus the shape and arrangement of the third lead-out portion 135b3 and the fourth lead-out portion 135b4 have a large effect on the characteristics of the coil component 101. As described for coil component 1, in the coil component 101, the first lead-out portion 125b1 includes the first bottom-side shaft portion V112 located closer to the coil axis Ax than the first top-side shaft portion V111, and the third lead-out portion 135b3 includes the third bottom-side shaft portion V142 located closer to the coil axis Ax than the third top-side shaft portion V141. Thus, a margin region having a larger volume than the region between the lead-out portion and the surface of the base body in conventional coil components is present between the first bottom-side shaft portion V112 and the first end surface 110c and between the third bottom-side shaft portion V142 and the first end surface 110c in the base body 110. Therefore, the magnetic flux generated by the change in electric current flowing through the first lead-out portion 125b1 and the third lead-out portion 135b3 can pass through the large margin region present between the first end surface 110c and these lead-out portions. Likewise, the second lead-out portion 125b2 includes the second bottom-side shaft portion V132 located closer to the coil axis Ax than the second top-side shaft portion V131, and the fourth lead-out portion 135b4 includes the fourth bottom-side shaft portion V162 located closer to the coil axis Ax than the fourth top-side shaft portion V161. Thus, a margin region having a larger volume than the region between the lead-out portion and the surface of the base body in conventional coil components is present between the second bottom-side shaft portion V132 and the second end surface 110d and between the fourth bottom-side shaft portion V162 and the second end surface 110d in the base body 110. Therefore, the magnetic flux generated by the change in electric current flowing through the second lead-out portion 125b2 and the fourth lead-out portion 135b4 can pass through the large margin region present between the second end surface 110d and these lead-out portions. Therefore, as with the coil component 1, the coil component 101 can have better magnetic characteristics and DC superposition characteristics than conventional coil components in which the lead-out portion extends at a uniform and narrow interval from the surface of the base body.
Next, a description is given of an example of a method of manufacturing the coil component 1. The coil component 1 can be manufactured by, for example, a lamination process. An example is hereinafter described of the manufacturing method of the coil component 1 by the sheet lamination.
To begin with, magnetic sheets are fabricated as precursors of the magnetic films constituting the base body 10 (the magnetic films 1 to 15). The magnetic sheets are fabricated as follows. For example, soft magnetic metal particles are mixed and kneaded with a resin to prepare a slurry. The slurry is then applied to a surface of a plastic base film using the doctor blade technique or any other common methods and dried, and the dried slurry is cut to a predetermined size.
Next, a through hole is formed in each of the magnetic sheets as the precursors of the magnetic films 11 to 14 at a predetermined position so as to extend through the magnetic sheets in the T axis direction. Following this, a conductive paste is printed by screen printing on the top surface of each of the magnetic sheets to be the magnetic films 11 to 14, so that an unfired conductor pattern is formed on each of the magnetic sheets. The through holes formed in the magnetic sheets are filled with the conductive paste. In this way, the unfired conductor pattern formed on the magnetic sheet as the precursor of the magnetic film 11 forms the first conductor pattern C11 after heating, and the unfired conductor pattern formed on the magnetic sheet as the precursor of the magnetic film 12 forms the second conductor pattern C12 after heating. The unfired conductor pattern formed on the magnetic sheet as the precursor of the magnetic film 13 forms the first connection portion C21 after heating. The conductor patterns can also be formed by any various known methods other than the screen printing.
The magnetic sheet as the precursor of the magnetic film 11 may be a single magnetic sheet or a laminated sheet constituted by multiple magnetic sheets stacked together. Likewise, each of the magnetic sheets as the precursors of the magnetic films 12 to 15 may be a single magnetic sheet or a laminated sheet constituted by multiple magnetic sheets stacked together. The thickness of each of the magnetic films 11 to 15 can be adjusted by adjusting the number of magnetic sheets that make up the magnetic films 11 to 15. To increase the volume of the margin region M1 by increasing the dimension of the first bottom-side shaft portion V12 in the T axis direction, the number of magnetic sheets constituting the magnetic film 14 can be larger than the number of magnetic sheets constituting the magnetic film 11 or 12. Since the magnetic film 15 serves as a cover layer over the top surface of the coil conductor 25, it may be constituted by multiple magnetic sheets to obtain the thickness necessary for the cover layer.
Next, the magnetic sheets as the precursors of the magnetic films 11 to 15 are stacked together to obtain a laminate. The magnetic sheets stacked together may be bonded together by thermal compression using a pressing machine to obtain a laminate. Then, the laminate is diced to a desired size by using a cutter such as a dicing machine or a laser processing machine to make a chip laminate. Polishing treatment such as barrel polishing may be performed on the end portions of the chip laminate, if necessary.
Next, the chip laminate is degreased and then subjected to thermal treatment, so that the base body 10 is obtained. The thermal treatment forms an oxide layer on the surface of each soft magnetic metal particle contained in the magnetic sheets, so that the adjacent soft magnetic metal particles are bonded to each other via the oxide layers. The thermal treatment is performed on the chip laminate at a temperature of 600° C. to 800° C. for a duration of 20 to 120 minutes.
Following this, a conductive paste is applied to the mounting surface 10b of the base body 10 to form the first and second external electrodes 21 and 22. A plated layer may also be included. The plated layer may include two or more layers. The two-layered plated layer may include a Ni plated layer and a Sn plated layer disposed on an outer side of the Ni plated layer. By the above-described process, the coil component 1 can be obtained.
It is also possible to produce the coil component 1 by the compression molding, thin film processing, slurry build or any other known methods.
The coil component 101 can also be manufactured in accordance with the manufacturing method of the coil component 1.
A part of the steps included in the above manufacturing method may be skipped as necessary. In the manufacturing 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 manufacturing 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 manufacturing method of the coil component 1 may be performed at the same time or in parallel, if possible.
The dimensions, materials, and arrangements of the constituent elements described for the above various embodiments 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. For example, in the embodiments shown in
Constituent elements not explicitly described herein can also be added to the above-described embodiments, and it is also possible to omit some of the constituent elements described for the embodiments.
The words “first,” “second,” “third” and so on used herein are added to distinguish constituent elements but do not necessarily limit the numbers, orders, or contents of the constituent elements. The numbers added to distinguish the constituent elements should be construed in each context. The same numbers do not necessarily denote the same constituent elements among the contexts. The use of numbers to identify constituent elements does not prevent the constituent elements from performing the functions of the constituent elements identified by other numbers.
Embodiments disclosed herein also include the following.
A coil component comprising:
The coil component of Additional Embodiment 1,
The coil component of Additional Embodiment 1 or 2,
The coil component of any one of Additional Embodiments 1 to 3,
The coil component of any one of Additional Embodiments 1 to 4,
The coil component of Additional Embodiment 5,
The coil component of any one of Additional Embodiments 1 to 6,
The coil component of any one of Additional Embodiments 1 to 7,
The coil component of any one of Additional Embodiments 1 to 8,
The coil component of any one of Additional Embodiments 1 to 9,
The coil component of any one of Additional Embodiments 1 to 10, wherein a number of turns of the winding portion in a circumferential direction around the coil axis is 3 or less.
A coil component comprising:
The coil component of Additional Embodiment 12, wherein a number of turns of the winding portion in a circumferential direction around the coil axis is 3 or less.
A coil component comprising:
The coil component of Additional Embodiment 14, wherein a number of turns of the winding portion in a circumferential direction around the coil axis is 3 or less.
A circuit board comprising the coil component of any one of Additional Embodiments 1 to 15.
An electronic component comprising the circuit board of Additional Embodiment 16.
Number | Date | Country | Kind |
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2022-088102 | May 2022 | JP | national |