Patent Publication Number: US-2020303113-A1

Title: Coil component

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to Korean Patent Application No. 10-2019-0030355 filed on Mar. 18, 2019 in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a coil component. 
     BACKGROUND 
     Coil components may be generally classified as a laminate type coil component, a wound type coil component, and a thin film type coil component. In the wound type coil component, a metal wire may be wound to form a wound type coil, and the wound type coil may be used as a coil in a component. 
     Since the wound type coil may be formed by a separate process, as compared with the conventional laminate type coil components and the conventional thin film type coil components, relatively weak coupling force with other constituents of the coil component may occur. As a result, in forming the body of the coil component, the wound type coil may flow and cause defects. 
     SUMMARY 
     An aspect of the present disclosure is to provide a coil component having improved coupling force between a wound coil and a lead frame. 
     Another aspect of the present disclosure is to provide a coil component in which contact resistance (Rdc) may be reduced by relatively increasing an area of a connection portion connecting the wound coil and the lead frame. 
     According to an aspect of the present disclosure, a coil component includes a body having one surface and the other surface facing each other; a wound coil embedded in the body; a first lead frame and a second lead frame, embedded in the body and each having one surface exposed to the one surface of the body to be spaced apart from each other; and a connection portion connecting at least one of the first and second lead frames and et least one end portion of the wound coil. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above and other aspects, features, and advantages of the present disclosure will be more clearly understood from the following detailed description, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic view illustrating a coil component according to an exemplary embodiment of the present disclosure. 
         FIG. 2  is a schematic view illustrating a disassembled coil component according to an exemplary embodiment of the present disclosure. 
         FIGS. 3 to 6  are schematic views illustrating a cross-section taken along line A-A′ in  FIG. 1 , respectively. 
     
    
    
     DETAILED DESCRIPTION 
     The terms used in the description of the present disclosure are used to describe a specific embodiment, and are not intended to limit the present disclosure. A singular term includes a plural form unless otherwise indicated. The terms “include,” “comprise,” “is configured to,” etc. of the description of the present disclosure are used to indicate the presence of features, numbers, steps, operations, elements, parts, or combination thereof, and do not exclude the possibilities of combination or addition of one or more additional features, numbers, steps, operations, elements, parts, or combination thereof. Also, the terms “disposed on,” “positioned on,” and the like, may indicate that an element is positioned on or beneath an object, and does not necessarily mean that the element is positioned above the object with reference to a gravity direction. 
     The term “coupled to,” “combined to,” and the like, may not only indicate that elements are directly and physically in contact with each other, but also include the configuration in which another element is interposed between the elements such that the elements are also in contact with the other component. 
     Sizes and thicknesses of elements illustrated in the drawings are indicated as examples for ease of description, and the present disclosure are not limited thereto. 
     In the drawings, an L direction is a first direction or a length direction, a W direction is a second direction or a width direction, a T direction is a third direction or a thickness direction. 
     Hereinafter, a coil component according to an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings. Referring to the accompanying drawings, the same or corresponding components may be denoted by the same reference numerals, and overlapped descriptions will be omitted. 
     In electronic devices, various types of electronic components may be used, and various types of coil components may be used between the electronic components to remove noise, or for other purposes. 
     In other words, in electronic devices, a coil component may be used as a power inductor, a high frequency (HF) inductor, a general bead, a high frequency (GHz) bead, a common mode filter, and the like. 
       FIG. 1  is a schematic view illustrating a coil component according to an embodiment of the present disclosure.  FIG. 2  is a schematic view illustrating a disassembled coil component according to an embodiment of the present disclosure.  FIGS. 3 to 6  are schematic views illustrating a cross-section taken along line A-A′ in  FIG. 1 , respectively. 
       FIGS. 3 to 6  are schematic views illustrating a coupling relationship between end portions of wound coils, lead frames, and connection portions, respectively, and illustrate modifications of the connection portions applied to an embodiment of the present disclosure. 
     Referring to  FIGS. 1 to 6 , a coil component  1000  according to an embodiment of the present disclosure may include a body B, a wound coil  300 , lead frames  410  and  420 , and external electrodes  610  and  620 . The body B may include a mold portion  100  and a cover portion  200 . The mold portion  100  may include a support portion  110  and a core  120 . 
     The body B may form an exterior of the coil component  1000  according to the present embodiment, and the wound coil  300  may be embedded therein. 
     The body B may be formed to have a hexahedral shape as a whole. 
     Referring to  FIG. 1 , the body B may include a first surface  101  and a second surface  102  facing each other in a longitudinal direction L, a third surface  103  and a fourth surface  104  facing each other in a width direction W, and a fifth surface  105  and a sixth surface  106  facing each other in a thickness direction T. Each of the first to fourth surfaces  101 ,  102 ,  103 , and  104  of the body B may correspond to wall surfaces of the body B connecting the fifth surface  105  and the sixth surface  106  of the body B. Hereinafter, both end surfaces of the body B may refer to the first surface  101  and the second surface  102  of the body B, and both side surfaces of the body B may refer to the third surface  103  and the fourth surface  104  of the body B. Further, one surface of the body B may refer to the sixth surface  106  of the body B, and the other surface of the body B may refer to the fifth surface  105  of the body B. 
     The body B may be formed such that the coil component  1000  according to the present embodiment in which the external electrodes  610  and  620  to be described later are formed has a length of 2.0 mm, a width of 1.2 mm, and a thickness of 0.65 mm, but is not limited thereto. 
     The body B may include the mold portion  100  and the cover portion  200 . The cover portion  200  may be disposed on the mold portion  100  with reference to  FIG. 1  to surround the entire surface, except for a lower surface of the mold portion. The first to fifth surfaces  101 ,  102 ,  103 ,  104 , and  105  of the body B may be formed by the cover portion  200 , and the sixth surface  106  of the body B may be formed by the mold portion  100  and the cover portion  200 . 
     The mold portion  100  may have one surface and the other surface facing each other, and may include the support portion  110  and the core  120 . The support portion  110  may support the wound coil  300 . The core  120  may be disposed at a central portion of the one surface of the support portion  110  through the wound coil  300 . For the above reason, the one surface and the other surface of the mold portion  100  may be used in the same meaning as the one surface and the other surface of the support portion  110 , respectively. 
     A distance from the one surface to the other surface of the support portion  110 , For example, a thickness of the support portion  110 , may be 200 μm or more. When the thickness of the support portion  110  is less than 200 μm, it may be difficult to ensure rigidity. A thickness of the core  120  may be 150 μm or more, but is not limited thereto. 
     Grooves corresponding to the lead frames  410  and  420  to be described later may be formed on the other surface of the support portion  110 . The grooves may be formed in the support portion  110  in a pressing and heating process for forming the cover portion  200  to be described later. Alternatively, the groove may be formed by a mold in the process of forming the mold portion  100 . 
     The cover portion  200  may cover the mold portion  100  and a wound coil  300  to be described later. The cover portion  200  may be disposed on the mold portion  100  and the wound coil  300 , and may be then pressed to be coupled to the mold portion  100 . 
     At least one of the mold portion  100  and the cover portion  200  may include a magnetic material. In the present embodiment, both the mold portion  100  and the cover portion  200  may include a magnetic material. The mold portion  100  may be formed by filling the magnetic material into a mold for forming the mold portion  100 . Alternatively, the mold portion  100  may be formed by filling a composite material containing a magnetic material and an insulating resin into the above-described mold. A molding process in which a high temperature and a high pressure may be applied to the magnetic material or the composite material in the mold may be additionally performed, but is not limited thereto. The support portion  110  and the core  120  may be integrally formed by a mold. The cover portion  200  may be formed of a magnetic composite sheet in which a magnetic material is dispersed in an insulating resin. Specifically, the cover portion  200  may be formed by arranging the magnetic composite sheet on the mold portion  100  and the wound coil  300 , and then heating and pressing the magnetic composite sheet. 
     The magnetic material may be a ferrite powder or a metal magnetic powder. 
     Examples of the ferrite powder may include at least one or more of spinel type ferrites such as Mg—Zn-based ferrite, Mn—Zn-based ferrite, Mn—Mg-based ferrite, Cu—Zn-based ferrite, Mg—Mn—Sr-based ferrite, Ni—Zn-based ferrite, and the like, hexagonal ferrites such as Ba—Zn-based ferrite, Ba—Mg-based ferrite, Ba—Ni-based ferrite, Ba—Co-based ferrite, Ba—Ni—Co-based ferrite, and the like, garnet type ferrites such as Y-based ferrite, and the like, and Li-based ferrites. 
     The metal magnetic powder may include at least one of iron (Fe), silicon (Si), chromium (Cr), cobalt (Co), molybdenum (Mo), aluminum (Al), niobium (Nb), copper (Cu), and nickel (Ni), and alloys thereof. For example, the metal magnetic powder may be at least one or more of a pure iron powder, a Fe—Si-based alloy powder, a Fe—Si—Al-based alloy powder, a Fe—Ni-based alloy powder, a Fe—Ni—Mo-based alloy powder, a Fe—Ni—Mo—Cu-based alloy powder, a Fe—Co-based alloy powder, a Fe—Ni—Co-based alloy powder, a Fe—Cr-based alloy powder, a Fe—Cr—Si-based alloy powder, a Fe—Si—Cu—Nb-based alloy powder, a Fe—Ni—Cr-based alloy powder, and a Fe—Cr—Al-based alloy powder. 
     The metallic magnetic powder may be amorphous or crystalline. For example, the metal magnetic powder may be a Fe—Si—B—Cr-based amorphous alloy powder, but is not limited thereto. 
     The ferrite powder and the metal magnetic powder may have an average diameter of about 0.1 μm to 30 μm, respectively, but are not limited thereto. 
     Each of the mold portion  100  and the cover portion  200  may include two or more types of magnetic materials. In this case, the term “different types of magnetic materials” means that magnetic materials dispersed in an insulating resin are distinguished from each other by an average diameter, a composition, crystallinity, and a shape. 
     The insulating resin may include an epoxy, a polyimide, a liquid crystal polymer, or the like, in a single form or in combined forms, but is not limited thereto. 
     The wound coil  300  may be embedded in the body B to exhibit the characteristics of the coil component. For example, when the coil component  1000  of the present embodiment is used as a power inductor, the wound coil  300  may store an electric field as a magnetic field such that an output voltage may be maintained, thereby stabilizing power of an electronic device. 
     The wound coil  300  may be disposed on the one surface of the mold portion  100 . Specifically, the wound coil  300  may be disposed on the one surface of the support portion  110 , in a wound type with respect to the core  120 . 
     The wound coil  300  may be an air-core coil, and may be composed of a rectangular coil. The wound coil  300  may be formed by spirally winding a metal wire such as a copper (Cu) wire of which surface is coated with an insulating material. 
     The wound coil  300  may be composed of a plurality of layers. Each layer of the wound coils  300  may be formed in a planar spiral shape, and may have a plurality of turns. For example, the wound coil  300  may form an innermost turn, at least one intermediate turn, and an outermost turn, outward from the central portion of the one surface of the mold portion  100 . 
     The lead frames  410  and  420  may be embedded in the body B, and one surface of each of the lead frames  410  and  420  may be exposed to the one surface of the body to be spaced apart from each other. Specifically, referring to  FIGS. 1 and 2 , the first lead frame  410  may include a first coupling portion  411  connected to one end portion  300   a  of the wound coil  300 , and a first extension portion  412  extending from the first coupling portion  411  to the other surface of the mold portion  100 . The second lead frame  420  may include a second coupling portion  421  connected to the other end portion  300   b  of the wound coil  300 , and a second extension portion  422  extending from the second coupling portion  421  to the other surface of the mold portion  100 . The first and second extension portions  412  and  422  may be spaced apart from each other in the other surface of the mold portion  100  in the longitudinal direction L of the body B, and may be respectively in an extended form in the width direction W of the body B. Each of the first and second coupling portions  411  and  421  may be formed to extend along the side surface of the mold portion  100 , to facilitate coupling with both end portions  300   a  and  300   b  of the wound coil  300 , and the end portions may be disposed at a position relatively higher than the one surface of the mold portion  100 . 
     The lead frames  410  and  420  may be members for connecting the both end portions  300   a  and  300   b  of the wound coil  300 , and first and second external electrodes  610  and  620 , disposed to face the sixth surface  106  of the body B, to each other. For example, in this embodiment, the both end portions  300   a  and  300   b  of the wound coil  300  and the first and second external electrodes  610  and  620  may be connected by the lead frames  410  and  420  for the manufacturing process efficiency. The mold portion  100  and the wound coil  300  may be formed in separate processes. Therefore, an operation of processing shapes of the both end portions  300   a  and  300   b  of the wound coil  300  into shapes corresponding to the side surface and the other surface of the mold portion  100  should be added, to lead the both end portions  300   a  and  300   b  of the wound coil  300  out to be spaced apart from each other, on the other surface of the mold portion  100 . For example, a copper wire or the like may be wound and processed into an individual form of the wound coil  300 , the individual wound coil  300  may be cut, and, then, both end portions  300   a  and  300   b  of the cut individual wound coil  300  should be processed into shapes corresponding to the side surface of the mold portion  100 . However, it may be not easy to process the shape of both end portions  300   a  and  300   b  of the wound coil  300  in view of the size and the like of the body B described above. Therefore, the present embodiment is to connect the both end portions  300   a  and  300   b  of the wound coil  300  and the external electrodes  610  and  620  by using the lead frames  410  and  420 , which are separate members. 
     The lead frames  410  and  420  may be formed by processing a metal plate material such as a copper film by a processing method such as punching, or the like. In this case, the coupling portions  411  and  421  and the extension portions  412  and  422  may be integrally formed, no boundary therebetween may occur. Since the scope of the present disclosure is not limited thereto, the coupling portions  411  and  421  and the extension portions  412  and  422  may be formed as separate members, respectively, such that a boundary between them may be formed. The lead frames  410  and  420  may include copper (Cu). 
     The connection portion  500  may connect the first and second lead frames  410  and  420  and the both end portions  300   a  and  300   b  of the wound coil  300 . The connection portion  500  may physically connect the lead frames  410  and  420  and the wound coils  300 , formed separately from each other. 
     The connection portion  500  may be interposed between the both end portions  300   a  and  300   b  of the wound coil  300  and the lead frames  410  and  420 , respectively. For example, as illustrated in  FIGS. 3 to 5 , a connection portion  500  may be interposed between the other end portion  300   b  of the wound coil  300  and the second lead frame  420 . Meanwhile, although not illustrated, the connection portion  500  may be also interposed between the one end portion  300   a  of the wound coil  300  and the first lead frame  410 . 
     A cross-sectional area of a region of the connection portion  500  disposed to face the sixth surface  106  of the body B (a lower portion from the viewpoint of  FIG. 3 ) may be smaller than a cross-sectional area of a region of the connection portion  500  disposed to face the fifth surface  105  of the body B (an upper portion from the viewpoint of  FIG. 3 ). As described above, the cover portion  200  may be formed by disposing the magnetic composite sheet on the mold portion  100  and the wound coil  300 , and then pressing and heating the magnetic composite sheet in a direction facing the mold portion  100 . The coupling force between the both end portions  300   a  and  300   b  of the wound coil  300 , the lead frames  410  and  420 , and the connection portion  500  may be weakened due to the pressure in the process. Therefore, although the pressure in the process, the cross-sectional area of the region in which the relatively high pressure is applied in the connection portion  500  (the upper portion from the viewpoint of  FIG. 3 ) may be increased to be larger than the cross-sectional area of the other region (the lower portion from the viewpoint of  FIG. 3 ), to secure the reliability of connection between the both end portions  300   a  and  300   b  of the wound coil  300 , the lead frames  410  and  420 , and the connection portion  500 . The connection portion  500  may be formed such that each of the upper and lower portions of the connection portion  500  include a curved surface. Therefore, the stress applied to the connection portion  500  in the above-described process may be dispersed. 
     A size of a crystal grain in a region of the connection portion  500  disposed to face the sixth surface  106  of the body B (a lower portion from the viewpoint of  FIG. 3 ) may be smaller than a size of a crystal grain in a region of the connection portion  500  disposed to face the fifth surface  105  of the body B (an upper portion from the viewpoint of  FIG. 3 ). Referring to  FIG. 3 , the connection portion  500  may be formed by disposing the other end portion  300   b  of the wound coil  300  and the coupling portion  421  of the second lead frame  420  to be in contact with each other, and then performing a laser welding operation in a region contacting the two. In this case, the laser may be irradiated from the upper portion to the lower portion of the above-described contact region, from the viewpoint of  FIG. 3 . Respective portions of the other end portion  300   b  of the wound coil  300  and the second lead frame  420  of the above-described contact region may be melted by the laser, and then solidified to form the connection portion  500 . In the above-described contact region, a difference in energy may arise due to a difference in distance from the laser light source. Therefore, the cross-sectional area of the region of the connection portion  500  disposed to face the sixth surface  106  of the body B (the lower portion from the viewpoint of  FIG. 3 ) may be formed to be smaller than the cross-sectional area of the region of the connection portion  500  disposed to face the fifth surface  105  of the body B (the upper portion from the viewpoint of  FIG. 3 ). In addition, a difference in cooling speed may occur in the connection region  500  in the solidification. Therefore, the size of the crystal grain in the region of the connection portion  500  disposed to face the sixth surface  106  of the body B (the lower portion from the viewpoint of  FIG. 3 ) may be formed to be smaller than the size of the crystal grain in the region of the connection portion  500  disposed to face the fifth surface  105  of the body B (the upper portion from the viewpoint of  FIG. 3 ). The size of the crystal grains may be determined, for example, m by the line intercept method. 
     Meanwhile, when the connection portion  500  is formed by a laser welding operation as described above, the wound coil  300 , the lead frames  410  and  420 , and the connection portion  500  may be integrally formed with each other through the above-described melting and solidification. Therefore, the contact resistance may be reduced, as compared with a case in which the both end portions  300   a  and  300   b  of the wound coil  300  and the lead frames  410  and  420  are in contact with each other. 
     The wound coil  300  and the first and second lead frames  410  and  420  may be formed of the same material, and the connection portion  500  may be formed of a material different from the wound coil  300  and the first and second lead frames  410  and  420 . Referring to  FIGS. 4 and 5 , for example, the wound coil  300  and the second lead frame  420  may be formed of copper (Cu), respectively, and the connection portion  500  disposed between the other end portion  300   b  of the wound coil  300  and the second lead frame  420  may be formed of a conductive material other than copper (Cu). For example, the connection portion  500  may be interposed between the other end portion  300   b  of the coil  300  and the second lead frame  420 , and then may be interconnected by a cold pressing operation. For example, the connection portion  500  may be formed of tin (Sn), nickel (Ni), silver (Ag), or the like. 
     The connection portion  500  may include a resin (R) and a conductive powder (F) dispersed in the resin. 
     The resin (R) may include an epoxy, a polyimide, a liquid crystal polymer, or the like, in a single form or in combined forms, but is not limited thereto. The conductive powder (F) may be formed of a conductive material such as copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), titanium (Ti), or alloys thereof, or may be a non-metallic material such as graphene. The conductive powder (F) may have an anisotropic shape or an anisotropic electric conductivity. For example, a metallic powder in the form of flakes may be used as the conductive powder (F), and a non-metallic powder of graphene having anisotropic electric conductivity may be used. 
     Each of the first and second lead frames  410  and  420  and the both end portions  300   a  and  300   b  of the wound coil  300  may be in contact with each other, and the connection portion  500  may be formed to cover each of the first and second lead frames  410  and  420  and the both end portions  300   a  and  300   b  of the wound coil  300 . For example, referring to  FIG. 6 , the second lead frame  420  and the other end portion  300   b  of the wound coil  300  may be in contact with each other, and the connection portion  500  may be formed along surfaces of the second lead frame  420  and the other end portion  300   b  of the wound coil  300 , to cover the above-described contact region. The connection portion  500  may be formed of solder, and may include tin (Sn). When the connection portion  500  is formed to cover the surfaces of the lead frames  410  and  420  and both end portions  300   a  and  300   b  of the wound coil  300 , the connection portion  500  may simply and rapidly connect the lead frames  410  and  420  and the wound coil  300 , compared to the above-described examples. 
     The first and second external electrodes  610  and  620  may be spaced apart from each other on the sixth surface  106  of the body B, for example, be formed on the first and second lead frames  410  and  420 , exposed on the other surface of the support portion  110 , to be spaced apart from each other on the sixth surface  106  of the body B. 
     The first and second external electrodes  610  and  620  may have a single-layer structure or a multilayer structure. For example, the first external electrode  300  may include a first layer comprising copper (Cu), a second layer disposed on the first layer and comprising nickel (Ni), and a third layer disposed on the second layer and comprising tin (Sn). The first and second external electrodes  610  and  620  may be formed by an electrolytic plating process, but is not limited thereto. 
     The first and second external electrodes  610  and  620  may be formed of a conductive material such as copper (Cu), aluminum (Al), silver (Ag), tin (Sn), gold (Au), nickel (Ni), lead (Pb), chromium (Cr), titanium (Ti), or alloys thereof, but is not limited thereto. 
     Although not illustrated in the drawings, the coil component  1000  according to the present embodiment may further include an insulation layer disposed in a region, except for a region in which the external electrodes  610  and  620  are disposed in the sixth surface  106  of the body B. The insulation layer may be used as a plating resist in forming the external electrodes  610  and  620  by an electrolytic plating process, but is not limited thereto. The insulation layer may also be disposed on at least a portion of the first to fifth surfaces  101 ,  102 ,  103 ,  104 , and  105  of the body B. 
     As one exemplary embodiment of the present disclosure, the would coil  300  may be horizontally disposed in the body B such that an axis of the wound coil  300  is parallel with a direction in which the fifth and sixth surfaces  105 ,  106  of the body B are facing, as illustrated in  FIG. 1 . 
     As another exemplary embodiment of the present disclosure, the would coil  300  may be vertically disposed in the body B such that an axis of the wound coil  300  is perpendicular to a direction in which the fifth and sixth surfaces  105 ,  106  of the body B are facing, as illustrated in  FIG. 7 . 
     According to the present disclosure, the coupling force between the wound coil and the lead frame may be improved and the defect rate may be reduced. 
     Further, according to the present disclosure, the contact resistance (Rdc) may be reduced by forming the connection area relatively large. 
     While example embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the scope of the present disclosure as defined by the appended claims.