Patent Publication Number: US-2019198234-A1

Title: Inductor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to Korean Patent Application No. 10-2017-0180629, filed on Dec. 27, 2017 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Field 
     The present disclosure relates to an inductor, and more particularly, to a power inductor. 
     2. Description of Related Art 
     Recently, high-performance, lightweight, small-sized components are required due to the development of portable wireless communications devices and wearable device power generation. In particular, high frequencies are increasingly used, and it is required to stably supply power in a used frequency region. Thus, due to having a function of suppressing a sudden change in current at a power source terminal, power inductors that can be used at high frequencies and at high currents, in accordance with the development of smartphones and wearable devices, are required. In order to maintain highly reliable component characteristics in harsh user environments, power inductors require a highly reliable product design but related art inductor components have a high possibility of short circuits occurring, due to a degradation of dielectric strength in spite of coating between coil patterns. 
     SUMMARY 
     An aspect of the present disclosure may provide an inductor capable of maintaining high reliability even in a harsh user environment. 
     According to an aspect of the present disclosure, an inductor may include: a body including a support member having a through hole, a coil disposed on at least one surface of the support member, having a plurality of coil patterns; and a magnetic material encapsulating the support member and the coil, and filling the through hole; and external electrodes disposed on external surfaces of the body. The coil includes a plurality of coil patterns and an insulating layer disposed on surfaces of the plurality of coil patterns to insulate the plurality of adjacent coil patterns from each other, and the insulating layer includes a ceramic material. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The above and other aspects, features and other 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 perspective view of an inductor according to an exemplary embodiment in the present disclosure; 
         FIG. 2  is a cross-sectional view taken along line I-I′ of  FIG. 1 ; and 
         FIG. 3  is a cross-sectional view of an inductor according to a modification of the inductor illustrated in  FIGS. 1 and 2 . 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. 
     Hereinafter, an inductor according to an exemplary embodiment in the present disclosure will be described, but it is not limited thereto. 
       FIG. 1  is a perspective view of an inductor according to an exemplary embodiment in the present disclosure, and  FIG. 2  is a cross-sectional view taken along line I-I′ of  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , an inductor  100  of the present disclosure includes a body  1  and external electrodes  2  disposed on external surfaces of the body  1 . 
     The external electrodes  2  may include first and second external electrodes  21  and  22  spaced apart from each other on the external surfaces of the body  1 , and the first and second external electrodes  21  and  22  may have opposite polarities. 
     The body  1  may have an upper surface and a lower surface opposing each other in the thickness direction T, a first end surface and a second end surface opposing each other in the length direction L, and a first side surface and a second side surface opposing each other in the width direction W, and have a substantially hexagonal shape. 
     It is illustrated that the first and second external electrodes  21  and  22  extend from the first and second end surfaces of the body  1  to portions of the upper surface, portions of the lower surface, and portions of the first and second side surfaces, but, without being limited thereto, the first and second external electrodes  21  and  22  may be modified to have an alphabet L shape or to be arranged only on the lower surface of the body  1 . 
     The body  1  may include a magnetic material  11  having magnetic properties. The magnetic material of the body  1  may be formed by providing ferrite or metal magnetic particles in a resin. The metal magnetic particles may include at least one selected from the group consisting of iron (Fe), silicon (Si), chrome (Cr), aluminum (Al), and nickel (Ni). The magnetic material encapsulates a coil inside the body  1 , and in this case, at least one magnetic sheet may be stacked or a molding scheme may be used. When the magnetic material is formed by utilizing a scheme of stacking a plurality of magnetic sheets, the plurality of magnetic sheets may be integrated without visible boundaries therebetween. In particular, when the scheme of stacking a plurality of magnetic sheets is utilized to form the magnetic material, an insulating layer formed on a surface of the encapsulated coil may be damaged by a force of compressing for lamination. However, the inductor of the present disclosure eliminates the possibility of damage to the insulating layer of the coil  12  by strengthening dielectric strength of the insulating layer. 
     The body  1  includes a coil  12  and a support member  13  provided in the magnetic material  11 . 
     The coil  12  includes a plurality of coil patterns  121  and  122 . According to schemes to form a plurality of coil patterns, inductors are classified as a multilayer inductor in which coil patterns are formed on a magnetic sheet and connected to each other through vias, a wound type inductor in which a coil is wound by utilizing a bobbin, or the like, and a thin film type inductor in which coil patterns are formed by applying plating to at least one of one surface and the other surface of a substrate. The inductor  100  of the present disclosure, including a support member and adopting the scheme of forming coil patterns on at least one of upper and lower surfaces of the support member, is a thin film type inductor. The thin film inductor is advantageous in forming a high-capacity inductor, which may be realized by increasing the number of turns and an aspect ratio of coil patterns. A cross-section of the coil patterns  121  and  122  may have a rectangular shape extending substantially in the thickness direction, and if necessary, an upper surface of the cross-section of the coil patterns may be modified to be convex or concave. In order to form the coil patterns  121  and  122 , plating is used, and, to this end, seed layers  121   a  and  122   a  having a predetermined pattern for formation of a coil pattern on the support member are included. There is no limitation in forming the seed layers  121   a  and  122   a . That is, a scheme of forming a thin film plating layer and subsequently patterning the thin film plating layer through exposure and development utilizing a dry film or a sputtering scheme may be used. Either scheme may be appropriately selected by a person skilled in the art according to manufacturing environments and conditions. Plating layers  121   b  and  122   b  for substantially determining an aspect ratio of the coil patterns may be disposed on the seed layers  121   a  and  121   b , respectively, and the plating layers  121   b  and  122   b  may be formed by performing plating a plurality of times. Here, if a desired thickness may be realized by performing plating once, plating may be performed only once. However, in the case of forming coil patterns having a high aspect ratio through single plating, the coil patterns may be grown in the thickness direction, leading to a problem that the coil patterns may not be uniformly grown in the width direction, as well as in the thickness direction. In particular, as the coil patterns are excessively grown, rather than uniformly grown, in the width direction, a short-circuit may occur between the coil patterns adjacent to each other. In order to prevent this, for example, an insulating pattern having openings having a shape corresponding to the coil patterns may be formed on the support member and plating is applied only to the inside of the openings. Through this method, a short circuit that may occur due to undesired overplating of coil patterns may be prevented in advance. The insulating pattern having openings is removed after the coil patterns are completely formed, and thus, a final inductor does not have the insulating pattern. 
     The coil  12  including the coil patterns  121  and  122  adjacent to each other is supported by the support member  13 . The support member  13  serves to assist formation of the coil  12  and to support the coil  12  by appropriate strength after completion of the coil  12 . The support member  13  includes a through hole H at the center thereof. As the through hole H is filled with the magnetic material, magnetic flux generated by the coil  12  may be strengthened. The support member  13  may further include a via hole near the through hole H, in addition to the through hole H. The via hole serves to form a via allowing an upper coil formed on one surface of the support member  13  and a lower coil formed on the other surface of the support member  13  to be electrically connected therethrough when the coil is disposed on both one surface and the other surface of the support member  13 . The upper and lower coils are substantially symmetrical in relation to the support member  13 . The via hole is filled with a conductive material and a specific shape thereof may be appropriately selected by a person skilled in the art. 
     The supporting member  13  including the through hole H may be formed as a thin plate. A material of the supporting member  13  is not limited and may be a thermosetting resin such as an epoxy resin, a thermoplastic resin such as polyimide, and a resin impregnated with a reinforcing material such as a glass fiber or an inorganic filler may be used. Specifically, the support member  13  may be a PID resin, a bismaleimide triazine (BT) resin, Ajinomoto build-up film (ABF), FR-4, or the like, but is not limited thereto. A specific thickness of the support member is not limited as long as it can appropriately support the coil  12  and may be within a range from 20 μm to 60 μm, for example. 
     The coil patterns  121  and  122  are supported on the support member  13  and a space between the coil patterns  121  and  122  is insulated by an insulating layer  14 . The insulating layer  14  is a ceramic insulating coating. The insulating layer  14  is formed by coating surfaces of the coil patterns  121  and  122  with a ceramic material such as silica, alumina, or the like, to enhance insulation properties, in particular, dielectric strength. This results in enhanced reliability of the inductor through insulation enhancement. 
     A scheme of forming the insulating layer  14  is not limited. For example, sputtering, chemical vapor deposition (CVD), atomic layer deposition (ALD), or the like, may be adopted and may be appropriately selected in consideration of characteristics required by a person skilled in the art and a manufacturing environment. 
     Since the insulating layer  14  includes a ceramic material, insulation reliability is superior to the case of coating a resin on the surface of the coil pattern. In particular, when a scheme of compressing a magnetic sheet to encapsulate the insulatedly coated coil with a magnetic material is used, the resin covering the coil is often damaged by an external force applied thereto. However, in the case of covering the coil with a ceramic material having excellent dielectric strength, the ceramic material may be rarely damaged in spite of an external force. As a result, a possibility of generating a short-circuit between coil patterns due to weakening of dielectric strength during a process of manufacturing the inductor or during user operation may be significantly reduced. 
       FIG. 3  is a cross-sectional view of an inductor  200  according to a modification of the inductor of  FIGS. 1 and 2 . The inductor  200  includes the substantially same components as those of the inductor  100  described above with reference to  FIGS. 1 and 2 , except for a structure of an insulating layer  214 , and thus, descriptions of the same components will be omitted for the purposes of description. 
     The inductor  200  is similar to the inductor  100  described above in that the inductor  200  is formed by directly arranging an insulating layer  214  formed of a ceramic material on surfaces of a plurality of coil patterns  221  and  222  to increase dielectric strength of the coil, but the inductor  200  further includes an insulating film  215  on the insulating layer  214 . Unlike the insulating layer  214  formed of a ceramic material, the insulating film  215  is formed of an organic material and, specifically, includes a parylene resin. In some cases, parylene is directly applied to a coil surface and used as a single insulating layer, but, in the inductor  200  of the present disclosure, parylene is not directly applied to a surface of the coil patterns, and the insulating layer formed of a ceramic material is first formed on the surfaces of the coil patterns and the insulating film including a parylene resin is secondly formed on the insulating layer. In this case, dielectric strength may be further strengthened, and the dual insulating structure strengthens dielectric strength and reliability even when an operating environment of the user is subject to harsh conditions such as high temperatures and high humidity. 
     There is no limitation in a method for forming the insulating film and any method may be used as long as it can form an organic material on the insulating layer formed of a ceramic material. For example, a CVD method may be utilized and, in this case, the insulating film may extend to an inner surface of a through hole in the support member. 
     As described above, the inductor, as a thin film type inductor in which the coil patterns are grown by utilizing the support member, including the insulating layer formed directly on the surfaces of the coil patterns to insulate the coil patterns adjacent to each other and including a ceramic material to enhance dielectric strength is provided. 
     As set forth above, according to exemplary embodiments of the present disclosure, the possibility of a defect due to a short circuit between coil patterns may be reduced by strengthening insulating properties between the plurality of coil patterns inside the coil of the inductor. In addition, in the inductor, since the insulating properties of the insulating layer disposed on the coil patterns are strengthened, when the magnetic material (i.e., magnetic particles) included in the body is compressed on the coil patterns, occurrence of dielectric breakdown of the insulating layer and a short-circuit defect between the magnetic material and the coil patterns due to mechanical stress based on the magnetic material may be effectively prevented. 
     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 disclosure as defined by the appended claims.