Patent Publication Number: US-10763032-B2

Title: Thin film-type inductor

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of priority to Korean Patent Application No. 10-2017-0085288, filed on Jul. 5, 2017 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a thin film-type inductor, and particularly, to a high capacity power inductor. 
     BACKGROUND 
     Due to high performance implemented in mobile devices such as smartphones and tablet PCs, an AP speed may be increased, while a resolution of an image to be displayed increases. Due to an increase in the power usage as a dual or quad core central processing unit (CPU) is used, a thin film-type inductor mainly used for a DC-DC converter and a noise filter requires low dc resistance to be implemented, with high inductance. 
     In addition, the miniaturization and thinning of various electronic devices are accelerating with the development of manufacturing technology. Accordingly, a thin film-type inductor used in such electronic devices is also required to be miniaturized and thinned. 
     To manufacture a small, high capacity thin film power inductor, a coil requires a high aspect ratio, and a body requires a highly charged magnetic sheet. However, even if a high-aspect-ratio coil and a highly charged body are implemented, loss characteristics need to be further improved in order to implement characteristics in a very small size. In detail, in the case of a via pad connecting an upper coil to a lower coil, although the influence on the entire DC resistance (Rdc) is not greatly affected, the characteristic deterioration may be produced through an electrode in the vicinity of the via pad. In addition, since there are limitations in reducing a size of a via, even if a thin film-type power inductor is miniaturized, a ratio of chip charging loss by the via pad tends to be higher as a thin film-type power inductor is miniaturized. 
     SUMMARY 
     An aspect of the present disclosure provides a structure preventing a loss of capacity while maintaining and improving electrical characteristics of a thin film-type power inductor, without changing a process to be complicated. 
     According to an aspect of the present disclosure, a thin film-type inductor includes a body, and a first external electrode and a second external electrode, each disposed on an external surface of the body. The body includes a support member, a first coil and a second coil and a magnetic material surrounding the support member. The first coil has a first end and a second end, and is disposed on an upper surface of the support member. The second coil has a first end and a second end, and is disposed on a lower surface of the support member. The support member includes a through-hole and a via electrode formed therein. A portion of one of an upper surface and a lower surface of the via electrode opposes the magnetic material. 
    
    
     
       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 perspective view of a thin film-type inductor according to an embodiment; and 
         FIG. 2  is a schematic cross-sectional view of an W-T plane with respect to region A of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present disclosure will be described as follows with reference to the accompanying drawings. In the accompanying drawings, shapes, sizes and the like, of the components may be exaggerated or shortened for clarity. 
     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 although the terms first, second, third, etc. may be used herein to describe various members, components, regions, layers and/or sections, any such 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 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 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 alone, in combination or in partial combination. 
     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, a thin film-type inductor according to an embodiment will be described, but embodiments are not limited thereto. 
     Thin Film-Type Inductor 
       FIG. 1  is a schematic perspective view of a thin film-type inductor according to an embodiment, while  FIG. 2  is a schematic cross-sectional view of an L-T plane with respect to region A of  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , a thin film-type inductor  100  according to an embodiment includes a body  1 , a first external electrode  21  and a second external electrode  22  disposed on an external surface of the body. The body  1  further includes a magnetic material  11  forming an outer cover of the body  1 , a support member  12  and a coil  13  sealed by the magnetic material  11 . The coil  13  includes a first coil  131  supported by an upper surface of the support member and a second coil  132  supported by a lower surface of the support member  12 . 
     The first external electrode  21  and the second external electrode  22  oppose each other in a length (L) direction of the body  1 , and are electrically connected to the first coil  131  and the second coil  132 , respectively. The first and second external electrodes  21  and  22  are formed of a material having excellent electrical conductivity. In  FIG. 1 , the first external electrode  21  and the second external electrode  22  are illustrated as having a “C shape”, but embodiments are not limited thereto. Alternatively, the first external electrode and the second external electrode may have an “L shape”, or may be formed of a bottom electrode. The first external electrode  21  and the second external electrode  22  need not have the same shape. For example, in an embodiment, the first external electrode  21  is C-shaped and the second external electrode  22  is L-shaped. 
     The body  1  forms an outer cover of a thin film-type inductor, and may include a first side surface and a second side surface opposing each other in a width (W) direction, a first end surface and a second end surface opposing each other in a length (L) direction, and an upper surface and a lower surface opposing each other in a thickness (T) direction. The various surfaces of the body  1  forma substantially hexahedral shape, but embodiments are not limited thereto. 
     The magnetic material  11  included in the body  1  may include a material having magnetic properties, and may be formed by filling, for example, a ferrite or metal-based soft magnetic material. The ferrite may include a known ferrite material such as 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 metal-based soft magnetic material may include one or more selected from the group consisting of iron (Fe), silicon (Si), chrome (Cr), aluminum (Al), nickel (Ni), and alloys thereof. For example, the metal-based soft magnetic material may include a Fe—Si—B—Cr based amorphous metal particle, but embodiments are not limited thereto. A particle size of the metal-based soft magnetic material may be 0.1 μm or more to 20 μm or less, and the metal-based soft magnetic material may be included while being dispersed in a polymer such as an epoxy resin, polyimide, or the like. 
     The first coil  131 , the second coil  132 , and the support member  12  may be sealed by the magnetic material. 
     The first coil  131  and the second coil  132  has a spiral shape as a whole, and each of the first coil  131  and the second coil  132  may have a first end and a second end. The first end  131   a  of the first coil  131  is connected to a via electrode  14  for being electrically connected to the second coil  132 . The second end  131   b  of the first coil  131  is electrically connected to a first external electrode  21 . Similarly, the first end  132   a  of the second coil  132  is connected to the via electrode  14  for being electrically connected to the first coil  131 , and the second end  132   b  of the second coil  132  is electrically connected to the second external electrode  22 . The first coil  131  and the second coil  132  are thin film-type coils formed while being supported on a support member  12 . Although not specifically illustrated, each of the first coil  131  and the second coil  132  are formed of a seed layer and a plating layer disposed above, and an aspect ratio (AR) of the coil is substantially determined by a thickness of the plating layer. 
     The first end  131   a  of the first coil is formed of a first via pad  14   a , and the first end  132   a  of the second coil is formed of a second via pad  14   b . Each of the first via pad  14   a  and the second via pad  14   b , as a region, of the first coil  131  and the second coil  132 , respectively, directly in contact with a via electrode  14 , is a portion supporting a via electrode passing through a support member. 
     A cross section of the first via pad  14   a  and the second via pad  14   b  has a shape of a circle from which at least a portion is removed, for example, a semicircular shape, or a shape whose portion is circular and having a larger area than that of the semicircular shape. In other words, the first via pad  14   a  and the second via pad  14   b  have a cross-section shape of a truncated circle. Typically, via pads have circular cross-sections, and have areas larger than an area of a cross section of the via electrode. In an embodiment, the cross section of the first via pad  14   a  and the second via pad  14   b  has a shape of a circle from which a portion is removed, so a free space to be filled with the magnetic material  11  may be secured, as much as a region having been removed from a circle, compared to the case in which a cross section of the via pads  14   a  and  14   b  has a shape of the circle. 
     The support member  12  supporting the first coil  132  and second coil  132  has a through-hole H in the center, and an interior of the through-hole is filled with the magnetic material  11  described above, so a core of the coil is provided. 
     The support member  12  functions to provide a substrate for a coil and to appropriately support the coil. In an embodiment, the support member  12  is provided in the form of a plate with insulation characteristics such as, for example, a PCB substrate, but embodiments are not limited thereto. A thickness of the support member  12  may be sufficient to support the coil (e.g.,  131  and/or  132 ), for example, about 60 μm. The support member  12  may include the via electrode  14  filled with a conductive material, in addition to the through-hole H. A cross section of the via electrode  14  may be substantially circular, but embodiments are not limited thereto. Alternatively, the cross section of the via electrode may have a tapered shape, in which a cross-section area becomes smaller from an external surface of the support member to the center, a reverse tapered shape, or a rectangular pillar shape. In an embodiment, where the cross section of the via electrode  14  is substantially circular, a diameter of the via electrode is 30 μm or more and 100 μm or less. Processing a via hole whose diameter is smaller than 30 μm may be difficult to be precisely controlled due to process variations. When a diameter is larger than 100 μm, an interior of a via hole may not be completely filled with a conductive material, so a via open short may occur. 
     Referring to  FIG. 2 , at least a portion of an upper surface, i.e., the portion forming the first via pad  14   a  of the via electrode  14  may oppose the magnetic material  11 , and at least a portion of a lower surface, i.e., the portion forming the second via pad  14   b  of the via electrode  14  may oppose the magnetic material  11 . In an embodiment, in a manner different from what is illustrated in  FIG. 2 , a portion of one of the upper surface or the lower surface of the via electrode may also be provided to oppose a magnetic material (not shown). In such embodiments, at least one side of a via electrode “opposing” a magnetic material indicates a structure having at least a surface of a via electrode opposing the magnetic material. It must be noted that a surface of the via electrode opposing the magnetic material does necessarily not indicate that the surface is directly in contact with the magnetic material, but that an additional insulating material may be interposed therebetween. As described above, as at least a portion of one of an upper surface and a lower surface of the via electrode  14  opposes a magnetic material, a space filled with a magnetic material may be significantly increased. 
     The first end  131   a  of the first coil  131  and a first filling portion  111  formed of the magnetic material  11  are disposed on an upper surface of the via electrode  14 . The first end  132   a  of the second coil  132  and a second filling portion  112  formed of the magnetic material  11  are disposed on a lower surface of the via electrode  14 . The first filling portion  111  and the second filling portion  112  are a portion of the magnetic material in the body  1 . 
     In a conventional thin film-type inductor, a first via pad, a first end of a first coil, a second via pad, and a first end of a second coil, are located in a region in which the first filling portion and the second filling portion are located. Moreover, conventionally, the first via pad and the second via pad have the same cross section as that of a via electrode disposed in a lower surface or an upper surface, while having a larger area than that of the via electrode. Thus, in conventional thin film-type inductor the first via pad and the second via pad are provided to completely cover the upper surface and the lower surface of the via electrode. 
     In contrast, in a thin film-type inductor according to an embodiment of the present disclosure, the first via pad  14   a  and the second via pad  14   b  are provided to cover a portion, but not the entirety, of an upper surface or a lower surface of the via electrode disposed in a lower surface or an upper surface. Additionally, a region, not covered by the first via pad  14   a  and the second via pad  14   b , of the upper surface or the lower surface of the via electrode  14  is provided with the magnetic material  11  disposed therein. As a result, compared to conventional thin film-type inductors, while electrical characteristics of DC resistance (Rdc), and the like are maintained, loss of filling of a magnetic material may be significantly reduced. Thus, in a thin film-type inductor, the first via pad and the second via pad are manufactured to be unnecessarily large, so a structure preventing a via pad portion from acting as the loss of filling a magnetic material may be provided. 
     Referring back to  FIG. 2 , an insulating material  15  is disposed between an upper surface of the via electrode  14  and the magnetic material  11  (i.e., a portion of a first filling portion) opposing the same, and an insulating material  15  is disposed between a lower surface of the via electrode  14  and the magnetic material  11  (i.e., a portion of a second filling portion) opposing the same. The insulating material  15  is provided to prevent a short occurring between the magnetic material  11  and the coil  13 , and is provided at the same time that a surface of the coil is coated for insulating after the coil is completely formed. A method of forming the insulating material  15  is not particularly limited, and chemical vapor deposition (CVD), sputtering deposition, or the like may be used. A material for the insulating material is sufficient as long as the material has insulating properties. For example, the material may include a phenylene resin or an epoxy resin. Here, the insulating material is further disposed. In this regard, because an additional insulating material is not required to be included, when a via electrode itself or a magnetic material itself has a configuration that enables insulation between the via electrode and the magnetic material. 
     As for the positional relationship between the via electrode  14  and each of the first coil  131  and the second coil  132 , a distance L 1  from the center C 1  of the via electrode  14  to the center C 2  of the first end  131   a  (i.e., the first via pad) of the first coil  131  is substantially the same as a distance L 2  from the center C 1  of the via electrode  14  to the center C 3  of the first end  132   a  (i.e., the second via pad) of the second coil, and has a value greater than 0. Moreover, directions, in which L 1  and L 2  are extended from the center of the via electrode, are opposite to each other. 
     In the thin film-type inductor described above, even when a size of a thin film-type power inductor is miniaturized, inductance (Ls) and saturated current (Isat) properties may be improved without loss of electrical characteristics of a chip. 
     As set forth above, according to an embodiment, a thin film-type power inductor maintaining and improving Ls and Isat characteristics without loss of electrical characteristics of a chip, even when a size of the thin film-type power inductor is miniaturized. 
     While 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.