Patent Publication Number: US-10312014-B2

Title: Inductor with improved inductance for miniaturization and method of manufacturing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit to priority of Korean Patent Application No. 10-2015-0156432 filed on Nov. 9, 2015, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to an inductor and a method of manufacturing the same. 
     A multilayer inductor may have a structure in which a plurality of insulating layers having conductor patterns formed thereon are stacked, in which the conductor patterns may be sequentially connected by conductive vias formed on each of the insulating layers and may overlap each other in a stacking direction to form a coil having a spiral structure. Further, both end portions of the coil may be drawn out to an external surface of a laminate to be connected to an external terminal. 
     Inductors are mainly surface mount device (SMD) type inductors mounted on circuit boards. High frequency inductors may be used at high frequencies of 100 MHz or above, and the use of high frequency inductors in the communications market is gradually increasing. The most important feature in high frequency inductors is securing quality factor Q characteristics representing efficiency of a chip inductor. In this case, Q=wL/R, in which the Q value is a ratio of inductance L and resistance R in a given frequency band. 
     A large number of components need to be mounted on a circuit board in a limited area, and therefore demand for the miniaturization of components is increasing. To secure the same degree of capacity while miniaturizing the inductor, there is a need to reduce a thickness or a line width of a coil pattern. In this case, Q characteristics may be reduced and the use frequency may be narrowed. 
     Therefore, there is a need to develop an inductor structure capable of securing inductance capacity and Q characteristics while miniaturizing the inductor. 
     SUMMARY 
     An external electrode may be formed on the external surface of a body, and therefore there may be a limitation in the miniaturization of the inductor. 
     An exemplary embodiment in the present disclosure may allow a size of an inductor to be reduced, secure Q characteristics and improve inductance by forming an external electrode on a body. 
     According to an exemplary embodiment in the present disclosure, an inductor may include: a body including a first surface and a second surface, a third surface and a fourth surface connecting the first surface and the second surface, and a coil disposed therein, the coil including first and second lead out portions extended toward the first surface; external electrodes disposed in the body, including a first external electrode connected to the first lead out portions and exposed to the first surface and the third surface of the body, and a second external electrode connected to the second lead out portions and exposed to the first surface and the fourth surface of the body, thereby allowing an inductor to be miniaturized, Q characteristics to be secured, and inductance to be improved. 
    
    
     
       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 schematically illustrating an inductor according to an exemplary embodiment in the present disclosure; 
         FIGS. 2 and 3  are a cross-sectional view schematically illustrating the inductor according to an exemplary embodiment in the present disclosure; and 
         FIGS. 4A through 4D  are plan and cross-sectional views schematically illustrating a method of manufacturing an inductor according to an exemplary embodiment in the present disclosure. 
     
    
    
     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 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 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” other elements, or “upper,” would then be oriented “below” the other elements or features, or “lower.” 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 is for describing particular embodiments only and is not intended to be limiting of the present disclosure. 
     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. 
     Hereinafter, an inductor  100  according to the present disclosure will be described. 
       FIG. 1  is a perspective view schematically illustrating an inductor according to an exemplary embodiment in the present disclosure and  FIGS. 2 and 3  are a cross-sectional view schematically illustrating the inductor according to an exemplary embodiment in the present disclosure. 
     Referring to  FIGS. 1 to 3 , an inductor according to an exemplary embodiment in the present disclosure may include a body  110  including a first and second surfaces  1  and  2 , and third and fourth surfaces  3  and  4  connecting the first and second surfaces  1  and  2 , and having a coil  120  disposed therein. The coil  120  includes a first lead out portion  121  (shown in foreground) and a second lead out portion  122  (shown in background) that extend toward the first surface  1 . External electrodes  131  and  132  are disposed in the body  110  and include a first external electrode  131  connected to the first lead out portion  121  and exposed to the first and third surfaces  1  and  3  of the body, and a second external electrode  132  connected to the second lead out portion  121  and exposed to the first and fourth surfaces  1  and  4  of the body. 
     The body  110  includes first and second surfaces  1  and  2  opposing each other in the thickness direction, third and fourth surfaces  3  and  4  opposing each other in the length direction, and fifth and sixth surfaces  5  and  6  opposing each other in the width direction. The insulating layers may be stacked in the width direction. 
     The body  110  may be formed by stacking the insulating layer, in which the insulating layer may include a magnetic material such as ferrite or a ceramic. 
     The insulating layers may be integrated so that boundaries between individual insulating layers after the firing may not be able to be confirmed without the use of a scanning electron microscope. A shape and dimensions of the body  110  and the number of stacked insulating layers are not limited to those of the exemplary embodiment in the present disclosure. 
     An interior of the body  110  may be provided with the coil. 
     The coil  120  may contain a conductive metal. 
     The coil  120  may be formed of a material containing silver (Ag) or copper (Cu) or alloys thereof, but is not limited thereto. 
     The coil  120  may include the first and second lead out portions  121  and  122  extended toward the first surface of the body. That is, the first and second lead out portions may extend toward the same surface. 
     The first and second lead out portions may respectively contact and be electrically connected to the first and second external electrodes  131  and  132  formed at the first surface  1  of the body  110 . 
     The coil  120  may comprise a plurality of coil patterns connected through conductive vias (not shown) and may be wound. 
     At least one of an upper portion and a lower portion of the body  110  may be provided with a cover layer  113  to protect the coil in the body  110 . 
     The cover layer  113  may be formed by printing a paste formed of the same material as the insulating layer at a predetermined thickness. 
     Existing inductors may have external electrodes formed on one or more external surfaces of the body. The size of the inductor may thus include the external electrode, making it difficult to miniature the inductor. Furthermore, a volume around the external electrode protruding from the body does not contribute to inductance, and therefore there may be a problem in that an amount of capacitance corresponding to the size of the inductor may not be secured. 
     The inductor  100  according to the exemplary embodiment in the present disclosure may include the external electrodes  131  and  132 , including the first external electrode  131  formed in the body  110  and exposed to the first and third surfaces  1  and  3  of the body and the second external electrode  132  exposed to the first and fourth surfaces  1  and  4  of the body, thereby improving inductance as compared to the same size of existing inductors, implementing the miniaturization of the inductor, and securing the Q characteristics. 
     The external electrodes  131  and  132  may have an “L” shape. 
     Referring to  FIG. 3 , a height of the portion of the external electrodes  131  and  132  respectively exposed to the third surface  3  and the fourth surface  4  of the body may be the same as a height (H 1 ) of the lead out portion of the coil  120 . As a result, an empty space may be formed between the coil positioned in the body and the external electrode to reduce permittivity of the body, thereby implementing the inductor in a high frequency region. 
     The external electrodes  131  and  132  may respectively be formed in the directions of the third surface and the fourth surface in the body  110  to be spaced apart from the coil  120 . 
     The first and second external electrodes  131  and  132  may respectively include conductive layers  131   a  and  132   a  and plating layers  131   b  and  132   b  formed on a surface of conductive layers. 
     The conductive layers  131   a  and  132   a  may be formed of a conductive metal material having excellent electrical conductivity. 
     The conductive metal material may include at least one of silver (Ag) and copper (Cu) or alloys thereof but is not limited thereto. 
     The plating layers  131   b  and  132   b  may be formed of nickel (Ni) or tin (Sn) but are not limited thereto. 
     In the conductive layers  131   a  and  132   a , the portion formed in the direction of the first surface  1  of the body may extend to have an outer surface aligned with the first surface  1  of the body. 
     In the plating layers  131   b  and  132   b , the respective portions formed in the directions of the third and fourth surfaces  3  and  4  of the body may extend to have their respective outer surfaces respectively aligned with the third and fourth surfaces  3  and  4  of the body. 
     The external electrodes  131  and  132  may be formed by penetrating the insulating layer  111  in the body  110  through a surface perpendicular to the stacking direction. The surface perpendicular to the stacking direction may be the first surface  1 , the second surface  2 , the third surface  3 , and/or the fourth surface  4  of the body, and the external electrode may be formed to penetrate through some of the first surface  1 , the third surface  3 , and the fourth surface  4  of the body. 
     Therefore, in the inductor according to the present disclosure, the external electrode may be disposed, at least partially, in the body to increase an internal area of the coil, thereby improving the inductance. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Inventive Inductor, 
                 Existing Inductor, 
               
               
                 Frequency 
                 Inductance (H) 
                 Inductance (H) 
               
               
                   
               
             
            
               
                 100 MHz 
                 3.8159 
                 3.5347 
               
               
                 500 MHz 
                 3.6735 
                 3.4202 
               
               
                 900 MHz 
                 3.6886 
                 3.4346 
               
               
                   
               
            
           
         
       
     
     Table 1 presents measured inductances at different frequencies for an inductor according to the exemplary embodiment in the present disclosure and for an existing inductor with external electrodes formed on the external surface of the body. The inductors were manufactured at the same size of 0603 (0.6*0.3*0.4 mm: L*W*T). 
     Referring to the above Table 1, it may be appreciated that, for this example, the inductor according to the exemplary embodiment in the present disclosure shows an improved inductance of as much as 7 to 8% compared to the existing inductor. 
     That is, the inductive capacity can be increased when the inductor includes the external electrode disposed, at least partially, in the body in comparison to an existing inductor with external electrodes formed on the external surface of the body. 
     Hereinafter, a method of manufacturing an inductor according to the present disclosure will be described. 
       FIGS. 4A through 4D  are a schematic process plan and cross-sectional views illustrating a method of manufacturing an inductor according to an exemplary embodiment in the present disclosure. 
     The method of manufacturing an inductor according to the exemplary embodiment in the present disclosure may include: forming an insulating layer  111  (not shown); forming coil patterns  120   a  and  120   b  on the insulating layer  111 , forming conductive patterns  131   a  and  132   a  in an opening of the insulating layer; forming a laminate (not shown) by stacking a plurality of the insulating layers on which the coil patterns  120   a  and  120   b  and the conductive patterns  131   a  and  132   a  are formed; and cutting and firing the laminate (not shown) to form a body  110  including a first electrode. 
     Referring to  FIG. 4A , the coil patterns  120   a  and  120   b  may be formed on the insulating layer  111  and the conductive patterns  131   a  and  132   a  may be formed in the opening. 
     The insulating layer  111  may be formed of a magnetic material such as ferrite. 
     The insulating layer  111  may be manufactured by mixing and dispersing the magnetic material and organic matters to manufacture slurry and then molding the slurry. 
     The coil patterns  120   a  and  120   b  may be formed by printing a conductive paste including conductive metal on the insulating layer. 
     The coil patterns  120   a  and  120   b  may use a material having excellent electric conductivity and may include conductive metal such as silver (Ag) or copper (Cu) or alloys thereof, but are not limited thereto. 
     The total stacked number of insulating layers  111  formed may be variously determined in consideration of electrical characteristics such as an inductance value required in the designed inductor component. 
     The total stacked number of insulating layers includes coil patterns without lead out portions (not shown) to be stacked in between coil pattern  120   a  and coil pattern  120   b.    
     Via electrodes (not shown) may be disposed in the insulating layers  111  to electrically connect conductive patterns of adjacent insulating layers. 
     The via electrodes connect the vertically disposed coil patterns, including conductive coil pattern  120   a , the conductive coil patterns without lead out portions, and conductive coil pattern  120   b , to thereby form the coil. 
     The via electrodes may be formed by forming a through hole in each of the insulating layers  111  in a location within the area where the conductive pattern will be formed, and then filling the through hole when forming the conductive pattern by printing the conductive paste on the insulating layer. 
     The conductive paste may be formed of at least one of silver (Ag), silver-palladium (Ag—Pd), nickel (Ni), and copper (Cu) or alloys thereof, but is not limited thereto. 
     The conductive patterns  131   a  and  132   a  may be formed by printing a conductive paste including conductive metal on the opening of the insulating layer. 
     The conductive patterns  131   a  and  132   a  are to form the external electrodes and may include the conductive metal. The conductive pattern may be formed by being printed in an “L” shape. 
     The conductive metal may be formed of a material including at least one of silver (Ag) and copper (Cu) or alloys thereof, but is not limited thereto. 
     The conductive patterns  131   a  and  132   a  may be formed to be spaced apart from the coil patterns without lead out portions upon the printing. 
     Referring to  FIG. 4B , a portion  150  of the conductive pattern formed on the insulating layer  111  may be removed. 
     The portion  150  of the conductive pattern may be a portion formed on a surface that will become the third or fourth surfaces  3  or  4  of the body. 
     The portion  150  of the conductive pattern may be removed by at least one of punching, laser etching, and etching processes. 
     By removing the portion  150  of the conductive pattern, a space in which the plating layer of the external electrodes is formed may be prepared within the region of the insulating layer. 
     Referring to  FIG. 4C , the insulating layers may be cut for stacking and firing to form the body  120  including the conductive layers  131   a  and  132   a  of the external electrodes. 
     Next, the body  110  may be pressed and hardened so that a filling rate of the body  110  may be maximum in methods such as pressing and vacuum pressing. 
     The body may be cut into individual chip units and thus a plurality of bodies  110  may be manufactured. As a result, the manufacturing costs of the inductor may be reduced and a high rate of productivity may be secured. 
     In the forming of the body, when the coil pattern is silver (Ag), it may be sintered under the general atmosphere and when the coil pattern is copper (Cu), may be performed under the reduction atmosphere. 
     Referring to  FIG. 4D , the plating layers  131   b  and  132   b  of the external electrodes may be formed on the conductive layers  131   a  and  132   a  of the external electrodes. 
     The plating layers  131   b  and  132   b  may be formed by plating nickel (Ni) or tin (Sn). 
     The external electrodes  131  and  132  including the first electrode and the second electrode may be disposed at least partially in the body  110  to secure the Q characteristics and increasing the area of the interior of the coil, thereby obtaining the improved inductance at the same size. 
     As set forth above, according to one exemplary embodiment of the present disclosure, the inductor may secure the Q characteristics and improve the inductance. 
     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 spirit and scope of the present disclosure as defined by the appended claims.