Patent Publication Number: US-9892841-B2

Title: Inductor

Description:
CROSS REFERENCE(S) TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. Section [120, 119, 119(e)] of Korean Patent Application Serial No. 10-2014-0103508, entitled “Inductor” filed on Aug. 11, 2014, which is hereby incorporated by reference in its entirety into this application. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an inductor, and more particularly, to a stack type inductor. 
     2. Description of the Related Art 
     An inductor is one of important passive devices constituting an electronic circuit along with resistance and a capacitor, and is widely used as a component that is mainly mounted in a power circuit such as a DC-DC converter included in an electronic device and that removes noise or constitutes an LC resonance circuit. In particular, a demand for a stack type inductor has been recently increased owing to development of an IT technology and small-sized and thin filmed electronic devices. 
     Meanwhile, efficiency may be improved by greatly reducing an inductor current through a coupled array structure including primary and secondary coils that are electromagnetically coupled in the inductor. A switch operates at a low frequency, which produces an effect of reducing a switching loss as well. 
     In the coupled array structure, according to a coupling degree of the primary and secondary coils, magnetizing inductance and leakage inductance occur. A phase difference between the two coils is 180 degrees, and magnetic fluxes thereof are coupled, which results in an effect in that a real ripple current is 2 times higher than that of a frequency. 
     SUMMARY 
     An object of the present disclosure is to provide an inductor that further reinforces an electromagnetic coupling of primary and secondary coils and that is advantageous to miniaturization by arranging the primary and secondary coils in a same space. 
     Another object of the present disclosure is to provide an inductor capable of improving production efficiency by using a conductor pattern having same shaped patterns. 
     According to an exemplary embodiment of the present disclosure, there is provided an inductor including a primary coil and a secondary coil in a ceramic main body, wherein the primary coil and the secondary coil are configured as multilayer conductor patterns connected through vias, and the conductor pattern constituting the primary coil and the conductor pattern constituting the secondary coil are alternately stacked. 
     In this regard, the conductor pattern constituting the primary coil, i.e., a primary conductor pattern, is formed on a first ceramic sheet, the conductor pattern constituting the secondary coil, i.e. a secondary conductor pattern, is formed on a second ceramic sheet, a first via connecting the primary conductor pattern is configured to pass through the second ceramic sheet, and a second via connecting the secondary conductor pattern is configured to pass through the second ceramic sheet. 
     In addition, the inductor includes a second via hole, as a penetration point of the first via, formed point away from the secondary conductor pattern in the second ceramic sheet, and a first via hole, as a penetration point of the second via, formed in a point away from the primary conductor pattern in the first ceramic sheet. 
     Meanwhile, as means for minimizing the number of pattern shapes of the conductor patterns, the primary conductor patterns of odd layers have a same pattern and the primary conductor patterns of even layers have a same pattern. As a same structure, the secondary conductor patterns of odd layers have a same pattern and the secondary conductor patterns of even layers have a same pattern. Furthermore, the primary conductor patterns of odd layers and the secondary conductor patterns of even layers are symmetrical in a diagonal direction, and the primary conductor patterns of even layers and the secondary conductor patterns of odd layers are symmetrical in the diagonal direction. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of an inductor according to an embodiment; 
         FIG. 2  is an exploded perspective view of an inductor according to an embodiment; and 
         FIGS. 3A through 3M  are plan views of first through seventh ceramic sheets included in an embodiment, in which  FIG. 3A  is a plan view of a third ceramic sheet in which a read pattern is formed,  FIGS. 3B through 3E  are plan views of a first ceramic sheet in which a primary conductor pattern is formed,  FIG. 3F  is a plan view of a fifth ceramic sheet in which a read pattern is formed,  FIG. 3G  is a plan view of a fourth ceramic sheet in which a read pattern is formed,  FIGS. 3H through 3K  are plan views of a second ceramic sheet in which a secondary conductor pattern is formed,  FIG. 3L  is a plan view of a sixth ceramic sheet in which a read pattern is formed, and finally  FIG. 3M  is a plan view of a seventh ceramic sheet stacked on an uppermost layer. 
     
    
    
     DESCRIPTION OF EMBODIMENT(S) 
     Various advantages and features of the present disclosure and technologies accomplishing thereof will become apparent from the following description of exemplary embodiments described with reference to the accompanying drawings. However, the present disclosure may be modified in many different forms and it should not be limited to the embodiments set forth herein. These embodiments may be provided so that this disclosure of these embodiments will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. 
     Terms used in the present specification are for explaining the embodiments rather than limiting the present disclosure. Unless explicitly described to the contrary, a singular form includes a plural form in the present specification. 
     For brevity and clarity of the illustration, the drawings illustrate the general structure, and in order to avoid an unnecessarily unclear discussion of the described embodiments of the disclosure, well-known features and detailed description of the technology may be omitted. Additionally, components of the drawing&#39;s are not necessarily illustrated according to scale. For example, the size of some components of the drawings may be exaggerated compared to the other elements to aid the understanding of the embodiments of the disclosure. The same reference numerals in different drawings represent the same components. 
     The construction and operation effect of the present disclosure will be described in more detail with reference to the accompanying drawings below. 
       FIG. 1  is a perspective view of an inductor according to an embodiment.  FIG. 2  is an exploded perspective view of an inductor according to an embodiment.  FIGS. 3A through 3M  are plan views of first through seventh ceramic sheets included in an embodiment, in which  FIG. 3A  is a plan view of a third ceramic sheet in which a read pattern is formed,  FIGS. 3B through 3E  are plan views of a first ceramic sheet in which a primary conductor pattern is formed,  FIG. 3F  is a plan view of a fifth ceramic sheet in which a read pattern is formed,  FIG. 3G  is a plan view of a fourth ceramic sheet in which a read pattern is formed,  FIGS. 3H through 3K  are plan views of a second ceramic sheet in which a secondary conductor pattern is formed,  FIG. 3L  is a plan view of a sixth ceramic sheet in which a read pattern is formed, and finally  FIG. 3M  is a plan view of a seventh ceramic sheet stacked on an uppermost layer. 
     Referring to  FIGS. 1 through 3M , an inductor  100  according to an embodiment includes a ceramic main body  110  and a primary conductor pattern  120  and a secondary conductor pattern  130  that are included in the ceramic main body  110 . For reference, although the primary conductor pattern  120  and the secondary conductor pattern  130  are formed of a same metal material, the primary conductor pattern  120  and the secondary conductor pattern  130  are distinctively illustrated for a clear description of the invention. 
     The ceramic main body  110  is a hexahedron formed of a ceramic material manufactured as a predetermined chip size, for example, a size corresponding to 012 (2.0 mm×1.2 mm×1.2 mm), 1005 (1.0 mm×0.5 mm×0.5 mm), 0603 (0.6 mm×0.3 mm×0.3 mm), 0402 (0.4 mm×0.2 mm×0.2mm), etc. and is completed by stacking, pressing, and sintering a plurality of ceramic sheets having a metal based ferrite such as Fe—Ni—Zn oxide, Fe—Ni—Zn—Cu oxide, or Fe, Ni, Fe—Ni(Permalloy) as a main component. Thus, adjacent ceramic sheets are integrated such that boundaries between the adjacent ceramic sheets may not be distinguished, and thus the ceramic main body  110  is formed. 
     In more detail, the ceramic sheet is configured as a first ceramic sheet  111  on which the primary conductor pattern  120  is formed and a second ceramic sheet  112  on which the secondary conductor pattern  130  is formed. The first ceramic sheet  111  and the second ceramic sheet  112  are alternately stacked. 
     The primary conductor pattern  120  and the secondary conductor pattern  130  are metal wires of a coil pattern formed of one or more materials selected from the group consisting of Ni, Al, Fe, Cu, Ti, Cr, Au, Ag, Pd, and Pt having an excellent conductivity, and may be respectively formed on the first ceramic sheet  111  and the second ceramic sheet  112  by screen printing, etc. 
     The primary conductor pattern  120  forms a primary coil that spirally circuits by electrically connecting each layer through a conductive via. The secondary conductor pattern  130  also forms a secondary coil by electrically connecting each layer through the conductive via. 
     In this regard, both ends of the primary and secondary coils are connected to a lead pattern  140  formed on a ceramic sheet for an external connection. That is, the primary conductor pattern  120  of an uppermost layer, i.e. the primary conductor pattern  120  formed on the first ceramic sheet  111  of  FIG. 3E , is connected to the lead pattern  140  formed on a fifth ceramic sheet  115 , and the secondary conductor pattern  130  of an uppermost layer, i.e. the secondary conductor pattern  130  formed on the second ceramic sheet  112  of  FIG. 3K , is connected to the lead pattern  140  formed on a sixth ceramic sheet  116 . An end of the lead pattern  140  formed on the fifth ceramic sheet  115  and the sixth ceramic sheet  116  is exposed to a side surface of the ceramic main body  110  and thus the lead pattern  140  is connected to an external terminal  150 . 
     The primary conductor pattern  120  of a lowermost layer, i.e. the primary conductor pattern  120  formed on the first ceramic sheet  111  of  FIG. 3B , is connected to the lead pattern  140  formed on a third ceramic sheet  113 , and the secondary conductor pattern  130  of a lowermost layer, i.e. the secondary conductor pattern  130  formed on the second ceramic sheet  112  of  FIG. 3H , is connected to the lead pattern  140  formed on a fourth ceramic sheet  114 . 
     An end of the lead pattern  140  formed on the third ceramic sheet  113  and the fourth ceramic sheet  114  is also exposed to the side surface of the ceramic main body  110  and thus the lead pattern  140  is connected to the external terminal  150 . Accordingly, the primary coil configured as the primary conductor pattern  120  is connected to the external terminal  150  that is an input and output end through the lead pattern  140  of the third ceramic sheet  113  and the lead pattern  140  of the fifth ceramic sheet  115  and thus the primary coil is electrically connected to the outside. Likewise, the secondary coil configured as the secondary conductor pattern  130  is also connected to the external terminal  150  that is the input and output end through the lead pattern  140  of the fourth ceramic sheet  114  and the lead pattern  140  of the sixth ceramic sheet  116  and thus the secondary coil is electrically connected to the outside. 
     Meanwhile, for protection from the outside, a seventh ceramic sheet  117  having no pattern may be additionally stacked on the sixth ceramic sheet  116 . Although the seventh ceramic sheet  117  is formed as one layer in the present embodiment, this is merely an example. The seventh ceramic sheet  117  may be configured as multilayers and may be disposed on a lower portion of the third ceramic sheet  113 . 
     Since the first ceramic sheet  111  and the second ceramic sheet  112  are alternately stacked, the primary conductor pattern  120  and the secondary conductor pattern  130  are also alternately stacked with the first ceramic sheet  111  or the second ceramic sheet  112  disposed therebetween. That is, the second ceramic sheet  112  on which the secondary conductor pattern  130  is formed is disposed between the primary conductor pattern  120  of an upper layer and the primary conductor pattern  120  of a lower layer, and the first ceramic sheet  111  on which the primary conductor pattern  120  is formed is disposed between the secondary conductor pattern  130  of an upper layer and the secondary conductor pattern  130  of a lower layer. 
     Therefore, vias connecting the primary conductor pattern  120  of each layer, i.e. first vias  121  and  122 , pass through the second ceramic sheet  112  disposed between the primary conductor pattern  120  of the upper layer and the primary conductor pattern  120  of the lower layer, and vias connecting the secondary conductor pattern  130  of each layer, i.e. second vias  131  and  132 , pass through the first ceramic sheet  111  disposed between the secondary conductor pattern  130  of the upper layer and the secondary conductor pattern  130  of the lower layer. For reference, the first vias  121  and  122  and the second vias  131  and  132  are illustrated as dotted lines connecting conductor patterns of each layer in  FIG. 1 . 
     A second via hole  112   a  is formed in a point of the second ceramic sheet  112  away from the second conductor pattern  130 . The first vias  121  and  122  pass through the second via hole  112   a . Accordingly, the first vias  121  and  122  do not contact the secondary conductor pattern  130  but connect only the primary conductor pattern  120  to form the primary coil. As a same structure, a first via hole  111   a  is formed in a point of the first ceramic sheet  111  away from the first conductor pattern  120 . The second vias  131  and  132  pass through the first via hole  111   a , and thus the second vias  131  and  132  do not contact the primary conductor pattern  120  but connect only the secondary conductor pattern  130  to form the secondary coil. 
     As described above, patterns constituting the primary coil and the secondary coil, i.e. the primary conductor pattern  120  and the secondary conductor pattern  130 , are alternately disposed in a same space in the present invention, and thus a magnetic coupling characteristic is further reinforced, and a volume of entire components is greatly reduced compared to a structure in which coils are individually formed in separate spaces, thereby preferably implementing miniaturization. 
     The primary conductor pattern  120  and the secondary conductor pattern  130  are formed in a coil shape, and thus both ends of the primary conductor pattern  120  and the secondary conductor pattern  130  are configured as inner ends  120   a  and  130   a  close to a coil center and outer ends  120   b  and  130   b  far away from the coil center. Thus, the first vias  121  and  122  are configured as the inner via  121  connecting the inner ends  120   a  of the primary conductor pattern  120  and the outer via  122  connecting the outer ends  120   b  of the primary conductor pattern  120 , and the inner via  121  and the outer via  122  change layers to connect the primary conductor pattern  120 . For example, the primary conductor pattern  120  of an n layer is connected to the primary conductor pattern  120  of an n- 1  layer just below the n layer through the inner via  121 , and the primary conductor pattern  120  of the n- 1  layer is connected to the primary conductor pattern  120  of an n- 2  layer just below the n- 1  layer through the outer via  122 . 
     Likewise, the second vias  131  and  132  are configured as the inner via  131  connecting the inner ends  130   a  of the secondary conductor pattern  130  and the outer via  132  connecting the outer ends  130   b  of the secondary conductor pattern  130 , and the inner via  131  and the outer via  132  change layers to connect the secondary conductor pattern  130 . 
     According to the above structure, the via hole  112   a  through which the inner via  121  of the first via passes, for example, the via hole  112   a  formed in the second ceramic sheet  112  disposed between the primary conductor pattern  120  of the n layer and the primary conductor pattern  120  of the n- 1  layer, is positioned in the inside of the secondary conductor pattern  130 . The via hole  112   a  through which the outer via  122  of the first via passes, for example, the via hole  112   a  formed in the second ceramic sheet  112  disposed between the primary conductor pattern  120  of the n- 1  layer and the primary conductor pattern  120  of the n- 2  layer, is positioned in the outside of the secondary conductor pattern  130 . 
     As a same structure, the via hole  111   a  through which the inner via  131  of the second via passes is positioned in the inside of the primary conductor pattern  120  in the first ceramic sheet  111 . The via hole  111   a  through which the outer via  132  of the second via passes is positioned in the outside of the primary conductor pattern  120  in the first ceramic sheet  111 . 
     As such, the inner via  121  of the first via or the inner via  131  of the second via passes through around a center potion of the second ceramic sheet  112  or the first ceramic sheet  111 , and thus there is no concern that the inner via  121  of the first via or the inner via  131  of the second via contacts the secondary conductor pattern  130  or the primary conductor pattern  120 . However, the outer via  122  of the first via or the outer via  132  of the second via passes through an edge of a ceramic sheet, and thus there is concern that the outer via  122  of the first via or the outer via  132  of the second via contacts the secondary conductor pattern  130  or the primary conductor pattern  120 . Although there is no such concern that the outer via  122  of the first via or the outer via  132  of the second via contacts the secondary conductor pattern  130  or the primary conductor pattern  120  if a margin portion is greatly formed by reducing sizes of the primary conductor pattern  120  and the secondary conductor pattern  130  (i.e. reducing a cross section area of a coil), deterioration of inductance may not be avoided. 
     Therefore, the secondary conductor pattern  130  is formed to have a pattern detouring the outer via  122  of the first via in a penetration part of the first via, in more detail, in a corner part through which the outer via  122  of the first via passes. Likewise, the primary conductor pattern  120  is formed to have a pattern detouring the outer via  132  of the second via in a penetration part of the second via, in more detail, in a corner part through which the outer via  132  of the second via passes. 
     Such detour patterns may be formed in various shapes. For example, as shown in  FIG. 3 , corners of the primary conductor pattern  120  and the secondary conductor pattern  130  are curved in a stairs shape to prevent the primary conductor pattern  120  and the secondary conductor pattern  130  from contacting the outer via  122  of the first via or the outer via  132  of the second via. However, this is merely an example. Any patterns may be applicable as long as the primary conductor pattern  120  and the secondary conductor pattern  130  do not contact the outer via  122  of the first via or the outer via  132  of the second via. 
     As such, detour patterns are applied to a part through which the outer via  122  of the first via or the outer via  132  of the second via passes by forming the primary conductor pattern  120  and the secondary conductor pattern  130  to be larger (i.e. forming a wide cross section area of the coil) in the present invention, thereby implementing high inductance while preventing contact between the outer via  122  of the first via and the secondary conductor pattern  130  and between the outer via  132  of the second via and the primary conductor pattern  120 . 
     Meanwhile, the primary conductor pattern  120  is partitioned as the primary conductor patterns  120  of odd layers and the primary conductor patterns  120  of even layers. The primary conductor patterns  120  of odd layers have a same pattern. The primary conductor patterns  120  of even layers have a same pattern. For example, the primary conductor patterns  120  of odd layers, i.e. the primary conductor patterns  120  formed on the first ceramic sheet  111  of  FIGS. 3B and 3D , as shown in  FIG. 3 , have patterns starting in the inner ends  120   a  formed near the center portion of the first ceramic sheet  111  and wired along an edge of the first ceramic sheet  111  and ending in the outer ends  120   b  formed near a corner of the first ceramic sheet  111 . 
     The primary conductor patterns  120  of even layers, i.e. the primary conductor patterns  120  formed on the first ceramic sheet  111  of  FIGS. 3C and 3E  have patterns starting at a point in which the primary conductor patterns  120  of odd layers end and wired along the edge of the first ceramic sheet  111  and curved in the corner part through which the outer via  132  of the second via passes in the stairs shape. 
     The above structure is applied to the secondary conductor pattern  130  as it is so that the secondary conductor patterns  130  of odd layers, i.e., the secondary conductor pattern  130  formed on the second ceramic sheet  112  of  FIGS. 3H and 3J , have a same pattern, and the secondary conductor patterns  130  of even layers, i.e. the secondary conductor pattern  130  formed on the second ceramic sheet  112  of  FIGS. 3I and 3K , have a same pattern. 
     In this regard, the primary conductor patterns  120  of odd layers and the secondary conductor patterns  130  of even layers are symmetrical in a diagonal direction, and the primary conductor patterns  120  of even layers and the secondary conductor patterns  130  of odd layers are symmetrical in the diagonal direction. That is, as shown in  FIG. 3 , the primary conductor patterns  120  of odd layers become the secondary conductor patterns  130  of even layers by rotating the primary conductor patterns  120  of odd layers by 180 degrees. Likewise, the primary conductor patterns  120  of even layers become the secondary conductor patterns  130  of odd layers by rotating the primary conductor patterns  120  of even layers by 180 degrees. Accordingly, the primary conductor patterns  120  of odd layers may be used as the secondary conductor patterns  130  of even layers as they are, and the primary conductor patterns  120  of even layers may be used as the secondary conductor pattern  130  of odd layers as they are, and thus both the primary conductor patterns  120  and the secondary conductor pattern  130  may be manufactured in two pattern shapes during manufacture, thereby greatly increasing production efficiency. 
     As set forth above, according to an exemplary embodiment of the present disclosure, a magnetic coupling characteristic of an inductor is further reinforced by alternately arranging respective patterns, i.e., a primary conductor pattern and a secondary conductor pattern, of a primary coil and a secondary coil in a same space. Volume of entire components may be greatly reduced compared to a structure in which the respective coils are individually formed in separate spaces, and thus the inductor is advantageous to implementing miniaturization. 
     As set forth above, according to an exemplary embodiment of the present disclosure, an inductor prevents a short-circuit between a primary conductor pattern and a second via and between a secondary conductor pattern and a first via by applying a detour pattern to the primary conductor pattern and the secondary conductor pattern, and simultaneously implements high inductance. 
     As set forth above, according to an exemplary embodiment of the present disclosure, an inductor may minimize types of conductor patterns according to pattern shapes and improve production efficiency since a primary conductor patterns of an odd layer and a secondary conductor pattern of an even layer are symmetrical to each other in a diagonal direction, and a primary conductor pattern of the even layer and a secondary conductor pattern of the odd layer are symmetrical to each other in the diagonal direction. 
     The detailed description described above is only to illustrate the present disclosure. Although the exemplary embodiments of the present disclosure have been described, the present disclosure may be also used in various other combinations, modifications, and environments. In other words, the present disclosure may be changed or modified within the range of concept of the disclosure disclosed in the specification, the range equivalent to the disclosure and/or the range of the technology or knowledge in the field to which the present disclosure pertains. The exemplary embodiments described above have been provided to explain the best state in carrying out the present disclosure. Therefore, they may be carried out in other states known to the field to which the present disclosure pertains in using other disclosures such as the present disclosure and also be modified in various forms required in specific application fields and usages of the disclosure. Therefore, it is to be understood that the disclosure is not limited to the disclosed embodiments. It is to be understood that other embodiments are also included within the spirit and scope of the appended claims.