Patent Publication Number: US-2018033541-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. 10-2016-0096197, filed on Jul. 28, 2016 with the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a coil component and a method of manufacturing the same. 
     2. Description of Related Art 
     An inductor, a type of coil component, may be combined with a capacitor to configure a resonance circuit, a filter circuit, or the like, for amplifying a signal within a specific frequency band, or as a typical passive 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 been accelerated. Research has been continuously carried out into the miniaturization and thinning of various devices applied to such IT devices, such as inductors, capacitors, transistors, and the like. 
     Despite such miniaturization, the level of performance required of a coil component is the same or slightly increased. In an inductor, 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 part is increased. 
     Generally, a core is formed in such a manner that a through hole is formed in the center of a coil part 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 an unfilled region is generated in a through hole, a reduction in characteristics of a coil component may occur. 
     Therefore, it is necessary to prevent a reduction in characteristics of a coil component and to provide a coil component that may maintain a uniform level of performance by reducing a rate of a change in an inductance value L with respect to using current and temperature. 
     SUMMARY 
     An aspect of the present disclosure provides a coil component including a nonmagnetic layer disposed in a core. 
     Another aspect of the present disclosure provides a method of manufacturing a coil component for efficiently manufacturing a coil component including a nonmagnetic layer disposed in a core. 
     According to an aspect of the present disclosure, a coil component includes: a coil part having a through hole in a center, including a coil surrounded by an insulating film, and having a first surface and a second surface opposing each other; a core disposed in the through hole and including a nonmagnetic layer; and cover portions disposed on the first surface and the second surface of the coil part. 
     According to another aspect of the present disclosure, a method of manufacturing a coil component includes: preparing a coil part having a through hole in a center, including a coil surrounded by an insulating film, and having a first surface and a second surface opposing each other, preparing a first magnetic sheet and a second magnetic sheet containing a magnetic particle, pressing the first magnetic sheet onto the first surface of the coil part to fill a portion of the through hole, and pressing the second magnetic sheet onto the second surface of the coil part to fill an unfilled region of the through hole. 
    
    
     
       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 8  are schematic cross-sectional views illustrating operations 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 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,” and “lower” and the like, may be used herein for ease of description to describe one element&#39;s relationship relative to another element(s) as 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 thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, elements, and/or groups thereof. 
     Hereinafter, embodiments of the present disclosure will be described with reference to schematic views illustrating embodiments of the present disclosure. In the drawings, for example, due to manufacturing techniques and/or tolerances, modifications of the shape shown may be estimated. Thus, embodiments of the present disclosure should not be construed as being limited to the particular shapes of regions shown herein, for example, to include a change in shape results in manufacturing. The following embodiments may also be constituted by one or a combination thereof. 
     The contents of the present disclosure described below may have a variety of configurations and propose only a required configuration herein, but are not limited thereto. 
     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 first and second end surfaces of the body in a longitudinal direction. 
     The body  110  may include a coil part  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 part  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 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 part  120  may include a coil having one or more layers. 
     For example, the coil part  120  may include a first coil  121   a  and a second coil  121   b.    
     When the coil part  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  have a plurality of layers, coils 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 a 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 and the second coil 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  may be disposed in a center of the coil part  120 , that is, in a through hole. 
     The core  130  may be formed by pressing a magnetic sheet containing a magnetic particle onto the through hole passing from the first surface  1  of the coil part  120  to the second surface  2  thereof. 
     A nonmagnetic layer  140  may be disposed inside of the core  130 . The nonmagnetic layer  140  may only be disposed inside the core  130 . 
     When a first magnetic sheet and a second magnetic sheet are pressed to form the core  130 , the nonmagnetic layer  140  may be formed in a location in which a first magnetic sheet is in contact with a second magnetic sheet. In other words, when the first magnetic sheet and the second magnetic sheet are pressed, since fluidity of epoxy resin, or the like, is higher than fluidity of a magnetic particle, the nonmagnetic layer  140  not containing a magnetic particle may be formed in the location in which the first magnetic sheet is in contact with the second magnetic sheet. 
     For example, the nonmagnetic layer  140  may be an epoxy layer. 
     Since the coil component  100  according to an exemplary embodiment includes the nonmagnetic layer  140  disposed in the core  130 , a portion of magnetic flux may be blocked, to reduce a rate of change in an inductance value L due to change in current, thereby maintaining a uniform level of performance. 
       FIG. 2  is an image of a cross 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 nonmagnetic layer  140  in which magnetic powder particles are not disposed inside of the core  130  is formed. A shape of the nonmagnetic layer  140  may be linear, but an exemplary embodiment is not limited thereto. Alternatively, as illustrated in  FIG. 2 , the shape of the nonmagnetic layer may be curved or circular. 
       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 , cores  231  and  232  according to the present exemplary embodiment may include a first core  231  whose width is gradually narrowed from the first surface  1  of a coil part  220  toward the second surface  2  thereof, and a second core  232  whose width is gradually narrowed from the second surface  2  of the coil part  220  toward the first surface  1  thereof. 
     When a through hole for formation of a core is formed in the coil part  220 , the through hole is not formed only a single surface of the first surface  1  or the second surface  2  of the coil part  220 , but in each of both surfaces of the coil part  220 . After the through hole is formed to allow each through hole to be connected to each other, the through hole is filled with a first magnetic sheet and a second magnetic sheet to form the first core  231  and the second core  232 . 
     When an aspect ratio of a core 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 the first core  231  and the second core  232  are formed, the through hole may be easily filled with a magnetic material. 
     In addition, a nonmagnetic layer  240  may be formed in a location in which the first core  231  is in contact with the second core  232 . 
     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 8  are schematic cross-sectional views illustrating operations in the method of manufacturing a coil component according to a different exemplary embodiment. 
     Hereinafter, with reference to  FIG. 4  and  FIGS. 5 to 8 , the method of manufacturing a coil component according to the present exemplary embodiment will be described. 
     First, as illustrated in  FIG. 5 , an operation S 10  of preparing a coil part  20  having a through hole  30 ′ in a center, including coils  21   a  and  21   b  surrounded by an insulating film  22 , and having a first surface  1  and a second surface  2 , is performed. 
     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. 
     The through hole  30 ′, as illustrated in  FIG. 3 , may include a first through hole whose width is gradually narrowed from the first surface  1  of the coil part  20  toward the second surface  2  thereof, and a second through hole whose width is gradually narrowed from the second surface  2  of the coil part  20  toward the first surface  1  thereof. 
     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 be a plurality of layers or a plurality of coils, as required. 
     For example, when the 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 screen printing, a process of exposure and development of photoresist, a spray coating process, or the like. 
     During, before or after the operation S 10  of preparing the coil part  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 a magnetic particle in epoxy resin, or the like, but an exemplary embodiment is not limited thereto. 
     The magnetic particle 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 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 filling a portion of the through hole  30 ′ by pressing the first magnetic sheet  11 ′ onto the first surface of the coil part  20  is performed. In addition, as illustrated in  FIG. 7 , an operation S 40  of pressing the second magnetic sheet  12 ′ onto the second surface  2  of the coil part  20  to fill an unfilled region of the through hole  30 ′ is performed. 
     In this case, the first magnetic sheet  11 ′ and the second magnetic sheet  12 ′ fill the through hole  30 ′ to form the core  30 . 
     In addition, in a portion of the core  30  in which the first magnetic sheet  11 ′ is in contact with the second magnetic sheet  12 ′, a nonmagnetic layer  40  not containing a magnetic particle due to a difference in fluidity between a magnetic particle and resin may be formed therein. 
     The nonmagnetic layer  40  may indicate a portion without a magnetic particle. 
     For example, the nonmagnetic layer  40  may be an epoxy layer. 
     Finally, an operation of forming external electrodes  51  and  52  is performed. 
     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 an electronic component according to the present 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 the present exemplary embodiment, since the first magnetic sheet  11 ′ is pressed onto the first surface of the coil part  20  to fill a portion of the through hole  30 ′ and the second magnetic sheet  12 ′ is pressed onto the second surface of the coil part  20  to fill an unfilled region of the through hole  30 ′, filling properties of the through hole  30 ′ may be improved. 
     As set forth above, according to an exemplary embodiment, since an electronic component includes a nonmagnetic layer disposed in a core, a rate of change of an inductance value L with respect to current and temperature may be small, thereby maintaining a uniform level of performance. 
     According to another exemplary embodiment, in a method of manufacturing a coil component, as a through hole having a high aspect ratio is filed with a magnetic particle to form a core, a first magnetic sheet and a second magnetic sheet are pressed onto two surfaces of a coil part, thereby improving a fill factor of a magnetic particle in a through hole. Therefore, a performance of the coil component may be improved. 
     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.