Patent Publication Number: US-2018033535-A1

Title: Coil component and method of manufacturing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to Korean Patent Application No. 10-2016-0096206, filed on Jul. 28, 2016 with the Korean Intellectual Property Office, the entirety of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to a coil component and a method of manufacturing the same. 
     2. Description of Related Art 
     An inductor, such as a coil component, may be combined with a capacitor through electromagnetism to provide a resonance circuit, a filter circuit, or the like, for amplifying a signal within a specific frequency band. The inductor can also be used as a typical passive component and coil component for removing noise while forming an electronic circuit together with a resistor and a capacitor. 
     In recent years, the miniaturization and thinning of information technology (IT) devices, such as communications devices and display devices, have accelerated. Research into the miniaturization and thinning of various devices such as inductors, capacitors, transistors, and the like, applied to such IT devices has been continuously carried out. 
     Despite such miniaturization, the level of performance required of a coil component is the same or slightly increased. In an inductor, such as a coil component, characteristics such as capacitance, direct current superposition characteristics, loss efficiency, and the like are considered important. 
     To improve characteristics of a coil component, a coil having a plurality of layers is provided. As a coil having a plurality of layers is provided, an aspect ratio of a core located in the center of a coil unit is increased. 
     Generally, a core is formed in such a manner that a through hole is formed in the center of a coil unit and the through hole is filled with a magnetic material. In this case, when an aspect ratio of a core is increased, a problem in which filling of the through hole is limited may occur. 
     Due to a high aspect ratio, when a region in which magnetic powder particles are not uniformly disposed is generated in a through hole, a reduction in characteristics of a coil component may occur. 
     Therefore, in a coil component, a method for improving filling properties of a magnetic particle in a through hole is required. 
     SUMMARY 
     An aspect of the present disclosure provides a coil component in which a magnetic particle is uniformly dispersed in a core and a method of manufacturing the same. 
     According to an aspect of the present disclosure, a method of manufacturing a coil component includes preparing a coil unit having a through hole in a center thereof. The coil unit includes a coil surrounded by an insulating film, and has a first surface and a second surface opposing each other. A first magnetic sheet and a second magnetic sheet each containing magnetic particles are prepared, and the first magnetic sheet is pressed onto a first surface of the coil unit to cause the first magnetic sheet to fill the through hole therewith. The second magnetic sheet is pressed onto a second surface of the coil unit. 
     According to another aspect of the present disclosure, a coil component includes a coil unit, a core, and first and second cover portions. The coil unit has a through hole in a center thereof, includes a coil surrounded by an insulating film, and has a first surface and a second surface opposing each other. The core is disposed in the through hole, the first cover portion is disposed on the first surface of the coil unit, and the second cover portion is disposed on the second surface of the coil unit. The first cover portion and the core are integrally formed of a first magnetic sheet, the second cover portion is formed of a second magnetic sheet, and a surface in which the core formed of the first magnetic sheet is in contact with the second cover portion formed of the second magnetic sheet is disposed outside of the coil unit. 
     According to another aspect of the present disclosure, method of manufacturing a coil component including forming a core to extend through a through hole of a coil unit including at least one coil encapsulated in an insulating film. In particular, the core is formed to extend outwardly through a surface of the coil unit. Following the forming of the core to extend outwardly through the surface of the coil unit, a magnetic substance sheet is pressed on the surface of the coil unit through which the core extends and on the core that extends outwardly through the surface of the coil unit. 
    
    
     
       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 cross-sectional view of a coil component according to an exemplary embodiment; 
         FIG. 2  is an image of a cross section of a coil component according to an exemplary embodiment, captured by an electron microscope; 
         FIG. 3  is a schematic cross-sectional view of a coil component according to another exemplary embodiment; 
         FIG. 4  is a flow chart of a method of manufacturing a coil component according to a different exemplary embodiment; and 
         FIGS. 5 to 9  are schematic cross-sectional views illustrating steps in a method of manufacturing a coil component according to a different exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present disclosure will be described as follows with reference to the attached drawings. 
     The present disclosure may, however, be exemplified in many different forms and should not be construed as being limited to the specific embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. 
     Throughout the specification, it will be understood that when an element, such as a layer, region, or wafer (substrate) is referred to as being “on,” “connected to,” or “coupled to” another element, it can be directly “on,” “connected to,” or “coupled to” the other element or other elements intervening therebetween may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to,” or “directly coupled to” another element, there may be no other elements or layers intervening therebetween. Like numerals refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     It will be apparent that though the terms first, second, third, etc. may be used herein to describe various members, components, regions, layers, and/or sections, these members, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one member, component, region, layer, or section from another member, component, region, layer, or section. Thus, a first member, component, region, layer, or section discussed below could be termed a second member, component, region, layer, or section without departing from the teachings of the exemplary embodiments. 
     Spatially relative terms, such as “above,” “upper,” “below,” “lower,” and the like, may be used herein for ease of description to describe one element&#39;s positional relationship relative to other element(s) as shown in an orientation shown in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “above” or “upper” relative to other elements would then be oriented “below” or “lower” relative to the other elements or features. Thus, the term “above” can encompass both the above and below orientations depending on a particular direction of the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may be interpreted accordingly. 
     The terminology used herein describes particular embodiments only, and the present disclosure is not limited thereby. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, members, elements, and/or groups, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, elements, and/or groups. 
     Hereinafter, embodiments will be described with reference to schematic views illustrating embodiments of the present disclosure. In the drawings, components having ideal shapes are shown. However, variations from these ideal shapes, for example due to variability in manufacturing techniques and/or tolerances, also fall within the scope of the disclosure. Thus, embodiments of the present disclosure should not be construed as being limited to the particular shapes of regions shown herein, but should more generally be understood to include changes in shape resulting from manufacturing methods and processes. The following embodiments may also be constituted by one or a combination thereof. 
     The present disclosure describes a variety of configurations, and only illustrative configurations are shown herein. However, the disclosure is not limited to the particular illustrative configurations presented herein, but extends to other similar/analogous configurations as well. 
     Coil Component 
       FIG. 1  is a schematic cross-sectional view of a coil component  100  according to an exemplary embodiment. 
     With reference to  FIG. 1 , the coil component  100  according to an exemplary embodiment may include a body  110 , as well as external electrodes  151  and  152  disposed on opposite end surfaces of the body in a longitudinal direction. 
     The body  110  may include a coil unit  120 , as well as a first cover portion  111  and a second cover portion  112  disposed on a first surface  1  and a second surface  2  of the coil unit  120 , respectively. 
     Since the first cover portion  111  and the second cover portion  112  are formed by pressing a magnetic sheet, magnetic flux may flow in the first cover portion  111  and the second cover portion  112 . 
     The body  110  may form an exterior of the coil component  100 , and may be formed of any material having magnetic properties without limitation. 
     The material having magnetic properties may be a ferrite powder or a magnetic metal powder. 
     The ferrite powder may be formed of Mn—Zn-based ferrite, Ni—Zn-based ferrite, Ni—Zn—Cu-based ferrite, Mn—Mg-based ferrite, Ba-based ferrite, Li-based ferrite, or the like. 
     The magnetic metal powder may include at least one selected from the group consisting of iron (Fe), silicon (Si), chromium (Cr), aluminum (Al), and nickel (Ni), and may be, for example, an Fe—Si—B—Cr-based amorphous metal, but an exemplary embodiment is not limited thereto. 
     A particle diameter of the ferrite powder or the magnetic metal powder may be in the range of 0.1 μm to 30 μm, and the ferrite powder or the magnetic metal powder may be included in the form in which the ferrite powder or the magnetic metal powder is dispersed in thermosetting resin such as epoxy resin, or the like. 
     The coil unit  120  may include a coil having one or more layers. 
     For example, the coil unit  120  may include a first coil  121   a  and a second coil  121   b.    
     When the coil unit  120  includes the first coil  121   a  and the second coil  121   b,  the coil component  100  may be used as a common mode filter. 
     When the first coil  121   a  and the second coil  121   b  each have a plurality of layers, coil windings located in different layers may be electrically connected to each other by a conductive via (not shown) as required. 
     In addition, one end of the first coil  121   a  and one end of the second coil  121   b  may be exposed to an exterior of the body  110  to be electrically connected to the external electrodes  151  and  152 , respectively. 
     The first coil  121   a  and the second coil  121   b  may be coated with an insulating film  122 . 
     The insulating film  122  may be formed using a method such as screen printing, a process of exposure and development of a photoresist, a spray coating process, or the like. 
     Since the first coil  121   a  and the second coil  121   b  are coated with the insulating film  122 , the first coil  121   a  and the second coil  121   b  may be electrically insulated from a magnetic material forming the body  110 . 
     The first coil  121   a  and the second coil  121   b  may be formed of silver (Ag) or copper (Cu). The first coil  121   a  and the second coil  121   b  may be formed by spirally printing conductive paste on a magnetic sheet, or by plating. 
     A core  130  is disposed in a center of the coil unit  120 . 
     The core  130  may be formed by filling a through hole, passing from the first surface  1  of the coil unit  120  to the second surface  2  thereof with a first magnetic sheet. 
     In this case, the first magnetic sheet forms a first cover portion  111  and the core  130 , and a second magnetic sheet forms a second cover portion  112 . 
     In a case of a coil component according to an exemplary embodiment, a surface  140  in which the first magnetic sheet is in contact with the second magnetic sheet may be disposed outside of (or spaced away from, or spaced apart from, or unaligned with the second surface  2  of) the coil unit  120 . 
     With reference to  FIG. 1 , when a location of a surface in which the coil unit  120  is in contact with the second cover portion  112  is A, and a location of the surface  140  in which the first magnetic sheet is in contact with the second magnetic sheet is B (where the surfaces A and B are parallel), B may be disposed further outwardly than A, based on a center of the body  110 . 
     When the first magnetic sheet and the second magnetic sheet are pressed on the first surface  1  and the second surface  2  of the coil unit  120 , respectively, to form the core  130 , due to a difference in fluidity between a magnetic particle contained in a magnetic sheet and a resin, a problem may occur in which an area in which magnetic powder particles are not uniformly disposed is formed inside of the core  130 . 
     However, in the coil component  100  according to an exemplary embodiment, since the surface  140  in which the first magnetic sheet is in contact with the second magnetic sheet is disposed outside of the coil unit  120 , a magnetic particle may be uniformly disposed inside of the core  130 . 
       FIG. 2  is an image of across section of the coil component  100  according to an exemplary embodiment, captured by an electron microscope. 
     With reference to  FIG. 2 , it is confirmed that the surface  140  in which a first magnetic sheet is in contact with a second magnetic sheet is disposed outside of the coil unit  120  (or offset from a lower surface of the coil unit  120 ). 
     In detail, it is confirmed that magnetic particles contained in the core  130  are uniformly distributed throughout the core  130 . 
     Thus, in the coil component  100  according to an exemplary embodiment, as the surface  140  in which the first magnetic sheet is in contact with the second magnetic sheet is disposed outside of the coil unit  120 , an area in which a magnetic particle is not uniformly disposed is prevented from being formed inside of the core  130 , thereby preventing a performance of the coil component  100  from being degraded. 
       FIG. 3  is a schematic cross-sectional view of a coil component  200  according to another exemplary embodiment. 
     A description of a configuration the same as or similar to the configuration described above will be omitted. 
     With reference to  FIG. 3 , a width of a core  230  included in the coil component  200  according to the other exemplary embodiment is narrowed (or tapered) from a first surface  1  of a coil unit  220  to a second surface  2  thereof. 
     When a through hole for formation of the core  230  is formed in the coil unit  220 , the through hole may be formed not to have sides that are perpendicular to the first surface  1  or the second surface  2 . Instead, the through hole may be formed to allow a width thereof to be gradually narrowed from the first surface  1  to the second surface  2 . 
     When an aspect ratio of a core having sides perpendicular to the first surface  1  or the second surface  2  is increased above a predetermined value, it becomes further difficult to form the core by filling the through hole. 
     However, in a manner the same as the coil component  200  according to another exemplary embodiment, when a width of the core  230  is formed to be gradually narrowed from the first surface  1  to the second surface  2 , the through hole may easily be filled with a magnetic material even when the aspect ratio of the core is above the predetermined value. 
     Method of Manufacturing a Coil Component 
       FIG. 4  is a flow chart illustrating a method of manufacturing a coil component according to a different exemplary embodiment, and  FIGS. 5 to 9  are schematic cross-sectional views illustrating operations or steps in the method of manufacturing a coil component according to the different exemplary embodiment. 
     Hereinafter, with reference to  FIG. 4  and  FIGS. 5 to 9 , a method of manufacturing a coil component according to the different exemplary embodiment will be described. 
     First, as illustrated in  FIG. 5 , an operation S 10  is performed to prepare a coil unit  20  having a through hole  30 ′ in a center thereof, including coils  21   a  and  21   b  surrounded by an insulating film  22 , and having a first surface  1  and a second surface  2 . 
     The through hole  30 ′ may be formed using mechanical drilling or laser drilling, but an exemplary embodiment is not limited thereto. For example, the laser drill may be a CO 2  laser or a YAG laser. 
     In some examples, the through hole  30 ′ may include a first through hole whose width is gradually narrowed from the first surface  1  of the coil unit  20  to the second surface  2 , as illustrated in  FIG. 3 , or a second through hole whose width is gradually narrowed from the second surface  2  of the coil unit  20  to the first surface  1 . 
     The coils  21   a  and  21   b  may be formed using conductive metal such as silver (Ag), copper (Cu), or the like. For a method of forming the coils  21   a  and  21   b,  after the coils  21   a  and  21   b  are formed by printing conductive paste on a magnetic sheet or plating, the coils  21   a  and  21   b  may be encapsulated by the insulating film  22 . 
     The coils  21   a  and  21   b  may include a plurality of layers or a plurality of coils, as required. 
     For example, when a coil component is a common mode filter, the coils  21   a  and  21   b  may include a first coil  21   a  and a second coil  21   b.    
     The insulating film  22  may be formed using a method such as a screen printing method, a process of exposure and development of photoresist, a spray coating process, or the like. 
     Concurrently with or before/after the operation S 10  of preparing the coil unit  20 , an operation S 20  of preparing a first magnetic sheet  11 ′ and a second magnetic sheet  12 ′ is performed. 
     The first magnetic sheet  11 ′ and the second magnetic sheet  12 ′ may be formed by dispersing magnetic particles in epoxy resin, or the like, but an exemplary embodiment is not limited thereto. 
     The magnetic particles may be particles of a ferrite powder or a magnetic metal powder. 
     The ferrite powder may be formed of Mn—Zn-based ferrite, Ni—Zn-based ferrite, Ni—Zn—Cu-based ferrite, Mn—Mg-based ferrite, Ba-based ferrite, Li-based ferrite, or the like. 
     The magnetic metal powder may include at least one selected from the group consisting of Fe, Si, Cr, Al, and Ni, and may be, for example, an Fe—Si—B—Cr-based amorphous metal, but an exemplary embodiment is not limited thereto. 
     A particle diameter of the ferrite powder or the magnetic metal powder may be 0.1 μm to 30 μm. 
     The first magnetic sheet  11 ′ and the second magnetic sheet  12 ′ may be a sheet having good fluidity and low viscosity. 
     Next, as illustrated in  FIG. 6 , an operation S 30  of entirely filling the through hole  30 ′ by pressing the first magnetic sheet  11 ′ on the first surface  1  of the coil unit  20  is performed. 
     In this case, the first magnetic sheet  11 ′ fills the through hole  30 ′ to form a core  30 . As a result, the first magnetic sheet  11 ′ will be provided as the core  30  and as a first cover portion  11 , as shown in  FIG. 7 . 
     Then, as illustrated in  FIG. 8 , an operation S 40  of pressing the second magnetic sheet  12 ′ on the second surface of the coil unit  20  is performed. As a result, the second magnetic sheet  12 ′ is provided as a second cover portion  12 . 
     However, after the first magnetic sheet  11 ′ is pressed on the first surface  1  of the coil unit  20 , an operation of etching the second surface  2  of the coil unit  20  before the second magnetic sheet  12 ′ is pressed on the second surface  2  of the coil unit  20  may be further included. 
     In detail, after the first magnetic sheet  11 ′ is pressed on the first surface  1  of the coil unit  20 , the coil unit  20  to which the first cover portion  11  is attached is turned upside down, and then, the second surface  2  of the coil unit  20  is etched. 
     With reference to  FIG. 7 , the second surface of the coil unit  20  is etched by a predetermined distance t to allow the first magnetic sheet  11 ′ filling the through hole  30 ′ to protrude from an etched surface of the coil unit  20 . 
     Through such an etching process with respect to the second surface the coil unit  20 , roughness of the second surface of the coil unit  20  is increased to additionally form a coupler, and thus, a bonding force of the coil unit  20  and the second magnetic sheet  12 ′ may be increased. 
     When the first magnetic sheet  11 ′ fills the through hole  30 ′, due to a difference in fluidity between magnetic particles and resin, a region in which magnetic powder particles are not uniformly disposed may be formed in an end of the first magnetic sheet  11 ′ filling the through hole  30 ′. The region in which magnetic powder particles are not uniformly disposed is removed in an etching process with respect to the second surface of the coil unit  20 , and thus, a magnetic particle may be uniformly disposed in the core  30  that remains in the coil unit  20 , as well as in cover portions  11  and  12 . 
     Finally, an operation of forming external electrodes  51  and  52  is performed, as shown in  FIG. 9 . 
     The external electrodes  51  and  52  may be formed in a method such as dipping, sputtering, or the like, but an exemplary embodiment is not limited thereto. 
     As compared with the case of using a magnetic paste according to the related art, the method of manufacturing a coil component according to a different exemplary embodiment has the advantages that material costs are low and a process is simple. 
     However, in the case in which a magnetic sheet is used, when the through hole  30 ′ is filled, a problem in which filling properties are reduced may occur. In detail, when an aspect ratio of the through hole  30 ′ is increased, filling properties of the through hole  30 ′ using a magnetic sheet may be further reduced. 
     However, in the method of manufacturing a coil component according to a different exemplary embodiment, since the first magnetic sheet  11 ′ is pressed on the first surface of the coil unit  20  to fill the through hole  30 ′, filling properties of the through hole  30 ′ may be improved. Furthermore, since a magnetic particle is uniformly disposed in the core  30 , a performance of the coil component manufactured in the method of manufacturing a coil component according to a different exemplary embodiment may be improved. 
     As set forth above, according to an exemplary embodiment, in a method of manufacturing a coil component, as a magnetic sheet containing a magnetic particle is pressed on a through hole having a high aspect ratio to form a core, a fill factor of a magnetic sheet in a through hole may be improved. In addition, as a magnetic particle is uniformly dispersed in a core, a performance of a coil component may be improved. 
     According to a different exemplary embodiment, in a coil component, as a contact surface of magnetic sheets disposed above and below a coil unit is disposed outside of the coil unit, a magnetic body may be continuously disposed inside of a core, thereby preventing a performance of a coil component from being degraded. 
     While exemplary 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 invention as defined by the appended claims.