Patent Publication Number: US-11037718-B2

Title: Coil component

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
     This application claims benefit of priority to Korean Patent Application No. 10-2017-0167532 filed on Dec. 7, 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 coil component and more particularly, to a thin-film type power inductor including a support member. 
     BACKGROUND 
     In accordance with the development of information technology (IT), apparatuses have been rapidly miniaturized and thinned. Therefore, a demand of a market for a small thin device has increased. 
     Korean Patent Laid-Open Publication No. 10-1999-0066108 provides a power inductor including a substrate having a via hole and coils disposed on opposite surfaces of the substrate and electrically connected to each other through the via hole of the substrate in accordance with such a technical trend to make an effort to provide an inductor including coils having uniform and high aspect ratios. However, there is still a limitation in forming the coils having the uniform and high aspect ratios due to a limitation in a manufacturing process. 
     SUMMARY 
     An aspect of the present disclosure may provide a coil component capable of decreasing an alignment mismatch problem between a plating layer and a seed layer in a coil pattern with a fine line width at the time of forming a coil pattern having a high aspect ratio using an anisotropic plating method. 
     According to an aspect of the present disclosure, a coil component may include: a body including a support member, a coil formed on the support member and including a plurality of coil patterns, and a magnetic material encapsulating the support member and the coil; and external electrodes disposed on an external surface of the body and electrically connected to the coil. The support member may include a plurality of groove portions recessed toward a central portion of the support member. The groove portions may be filled with an embedded coil pattern of the coil. A conductor layer of the coil may be stacked on the embedded coil pattern. 
    
    
     
       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 an inductor according to a first exemplary embodiment in the present disclosure; 
         FIG. 2  is a cross-sectional view taken along line I-I′ of  FIG. 1 ; 
         FIGS. 3A through 3I  illustrate an example of a method of manufacturing the inductor of  FIGS. 1 and 2 ; 
         FIG. 4  is a cross-sectional view of an inductor according to a second exemplary embodiment in the present disclosure; 
         FIG. 5  is a cross-sectional view of an inductor according to a third exemplary embodiment in the present disclosure; 
         FIG. 6  is a cross-sectional view of an inductor according to a fourth exemplary embodiment in the present disclosure; 
         FIG. 7  is a cross-sectional view of an inductor according to a fifth exemplary embodiment in the present disclosure; 
         FIG. 8  is a cross-sectional view of an inductor according to a sixth exemplary embodiment in the present disclosure; 
         FIG. 9  is a cross-sectional view of an inductor according to a seventh exemplary embodiment in the present disclosure; and 
         FIG. 10  is a cross-sectional view of an inductor according to an eighth exemplary embodiment in the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. 
     Hereinafter, a coil component according to an exemplary embodiment in the present disclosure will be described, but is not necessarily limited thereto. 
     First Exemplary Embodiment 
       FIG. 1  is a perspective view of a coil component  100  according to a first 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  may include a body  1  and external electrodes  2  disposed on an external surface of the body  1 . The external electrodes  2  may include first and second external electrodes  21  and  22  facing each other and having different polarities from each other. 
     The body  1  may substantially form an exterior of the inductor  100 , have upper and lower surfaces opposing each other in a thickness (T) direction, first and second end surfaces opposing each other in a length (L) direction, and first and second side surfaces opposing each other in a width (W) direction, and have a substantially hexahedral shape. 
     The body  1  may contain a magnetic material  11 . As the magnetic material  11 , any material may be used as long as it has magnetic properties. For example, the magnetic material  11  may be ferrite or a material in which metal magnetic particles are filled in a resin. The metal magnetic particle may contain one or more selected from the group consisting of iron (Fe), silicon (Si), chromium (Cr), aluminum (Al), and nickel (Ni). 
     The magnetic material  11  may serve as an encapsulant encapsulating a support member  12  to be described below and a coil  13  supported by the support member  12 . Coil patterns disposed on opposite sides of the support member  12  may be electrically connected to each other through a via hole V in the support member  12 . For example, a conductor layer  132  of the coil  13  to be described later may fill the via hole V. The support member  12  may have a through hole H filled with the magnetic material  11 . 
     The support member  12  may serve to support the coil  13  and to allow the coil  13  to be more easily formed. The support member  12  may be suitably selected by those skilled in the art as long as it contains a material having suitable rigidity in order to support the coil  13  and insulation properties, and the support member  12  may have a thin plate shape. The support member  12  may mean, for example, a central core of a copper clad laminate (CCL) known in the art. Alternatively, a photo imageable dielectric (PID) resin, an ajinomoto build-up film (ABF), or the like, may also be used as the support member  12 . The support member  12  may also have a structure in which prepreg, glass fiber, or the like is impregnated in a thin plate type insulating resin. 
     The support member  12  may have a plurality of groove portions  12   h  formed in one surface  12   a  and the other surface  12   b  of the support member  12  opposing each other. An embedded coil pattern  131  may be filled in the groove portion  12   h . The embedded coil pattern  131 , which is a portion of the coil  13  supported by the support member  12 , may substantially serve as a seed layer of the coil  13 . A cross-sectional shape of the embedded coil pattern  131  is not particularly limited, but in consideration of convenience of a process, the cross-sectional shape of the embedded coil pattern  131  may be a tetragon. A depth T 1  of the groove portion  12   h  may be less than ⅓ of an entire thickness T of the support member. When the depth of the groove portion  12   h  is greater than ⅓ of the entire thickness of the support member  12 , the support member  12  may not maintain rigidity enough to support the coil  13 , or a defect that the groove portions  12   h  on one surface and the other surface of the support member  12  penetrate through each other may occur. 
     The conductor layer  132  of the coil  13  may be disposed on the embedded coil pattern  131 . The conductor layer  132  may be a plating layer growing on the embedded coil pattern  131  serving as the seed layer. A cross section of the conductor layer  132  may be a tetragon similarly to the cross section of the embedded coil pattern  131 . However, unlike the embedding coil pattern  131  having a thickness of about 20 μm or so, the conductor layer  132  may have a thickness of 150 μm to 200 μm, such that the conductor layer  132  may substantially determine an aspect ratio of the coil pattern. 
     Materials of the embedded coil pattern  131  and the conductor layer  132  are not particularly limited as long as they have excellent electrical conductivity, and these material may be different from each other, but when the embedded coil pattern  131  and the conductor layer  132  are formed of the same material as each other, adhesion between the embedded coil pattern  131  and the conductor layer  132  may be improved. For example, the embedded coil pattern  131  and the conductor layer  132  may be formed of the same kind of Cu alloy. 
     The conductor layer  132  may become fine so as to have a line width of about 30 μm or so. In this case, it may be easy to match alignment between the seed layer and the conductor layer as compared to a case in which a conductor layer is formed based on a general seed layer instead of the embedded coil pattern. For example, in a case in which a seed layer is embedded in a support member in advance to configure an embedded coil pattern, when an opening portion is formed through exposure and development after laminating an insulator on the support member, even though the remaining insulator is at least partially disposed on the embedded coil pattern, an alignment defect of the coil pattern does not occur. However, in a case which the seed layer protrudes, a position at which the remaining insulator may be disposed without the alignment defect of the coil pattern may be more restrictive. 
     The coil pattern including the embedded coil pattern  131  and the conductor layer  132  may be enclosed by an insulating layer  14 , such that adjacent coil patterns may be insulated from each other, and the coil pattern  13  and the magnetic material  11  may be insulated from each other by the insulating layer  14 . A thickness of the insulating layer  14  is not particularly limited, but may be about 1 μm or more to 10 μm or less. When the thickness of the insulating layer  14  is less than 1 μm, insulation reliability may not sufficiently secured, and when the thickness of the insulating layer  14  is more than 10 μm, a space to be filled with the magnetic material may be restricted. 
     Even though the conductor layer has a high aspect ratio, adjacent conductor layers may have the same thickness as each other and each of the conductor layers may have a substantially rectangular cross-sectional shape, which are characteristics derived from a manufacturing process of an inductor to be described below. However, a manufacturing process of an inductor to be described below is provided by way of example, and may be suitably changed by those skilled in the art. Alternatively, a different manufacturing process may be selected by those skilled in the art. 
       FIGS. 3A through 3I  illustrate a manufacturing process of the inductor  100  according to the first exemplary embodiment. First, as illustrated in  FIG. 3A , a carrier substrate  31  including a conductive film  33  may be prepared. A releasing film  33 A may be disposed between the conductive films  33  and the carrier substrate  31 . Next, as in  FIG. 3B , a dry film resist (DFR) film  32  may be stacked on the carrier substrate  31 . As illustrated in  FIG. 3C , the DFR film  32  may be patterned by exposure and development, and then, using the patterned DFR film  32  as an etching mask, a seed layer  33  may be formed by etching the conductive film  33 . Thereafter, the DFR film  32  may be removed. Then, repeating the processes shown in  FIGS. 3A-3C  to form another structure similar to that shown in  FIG. 3C . As illustrated in  FIG. 3D , the two seed layers  33  of the two prepared structures may be disposed to face each other with an insulating material  34  interposed therebetween by a V-press. Then, as illustrated in  FIG. 3E , a support member  12  including these two seed layers  131  may be separated from the carrier substrates  31  and the releasing films  33 A. Next, as illustrated in  FIG. 3F , a via hole V may be formed by processing the via hole, and as illustrated in  FIG. 3G , insulators  35  may be laminated on upper and lower surfaces of the support member  12 , respectively, and patterned by exposure and development so as to have opening portions  35   h . Here, the seed layer  131  embedded in the support member  12  needs to be at least partially exposed by the opening portions  35   h . As illustrated in  FIG. 3H , a conductive material may be filled in the opening portions  35   h  to form a conductor layer  132 . Here, a thickness of the insulator  35  may be substantially equal to or thicker than that of the conductor layer  132 . As illustrated in  FIG. 3I , the insulator  35  may be removed, and an insulating layer  14  may be disposed on a surface of the conductor layer  132  exposed by removing the insulator  35 . In this case, an insulating resin may be coated by a chemical vapor deposition method or an insulating sheet may be laminated, in order to form the insulating layer  14 . Further, a cavity process for forming a through hole H may be simultaneously performed at the time of removing the insulator  35 . Next, although not specifically illustrated, a coil component may be completed through a general finishing method. 
     Except for the description described above, a description of features overlapping those of the above-mentioned coil component according to the first embodiment in the present disclosure will be omitted. 
     Second Exemplary Embodiment 
     Next,  FIG. 4  is a cross-sectional view of a coil component  200  according to a second exemplary embodiment in the present disclosure. The coil component  200  according to the second exemplary embodiment is different from the coil component  100  according to the first exemplary embodiment in that a central line C 1  of a line width of an embedded coil pattern does not coincide with a central line C 2  of a line width of a plating layer formed thereon. For convenience of explanation, a description of configurations overlapping those of the coil component  100  according to the first exemplary embodiment described above will be omitted, and a difference therebetween will be mainly described. 
     Referring to  FIG. 4 , a coil  213  of the coil component  200  may include an embedded coil pattern  2131  embedded in a support member  212  and a conductor layer  2132 . The central line of the line width of the embedded coil pattern  2131  may be spaced apart from the central line of the line width of the conductor layer  2132  by a predetermined interval. This corresponds to a case in which alignment of the embedded coil pattern  2131  with respect to a reference pattern and alignment of the conductor layer  2132  with respect to the reference pattern do not coincide with each other. Generally, when alignments of respective coil layers do not coincide with each other, a disconnection problem such as an open failure, or the like, may easily occur, but in the coil component  200 , even though the alignments of respective coil layers do not coincide with each other, since the embedded coil pattern  2131  serving as a seed layer is in a state in which the embedded coil pattern  2131  is stably embedded in the support member  212 , occurrence of the disconnection problem such as the open failure, or the like, may be significantly decreased as long as at least a portion of an upper surface of the embedded coil pattern  2131  and at least a portion of a lower surface of the conductor layer  2132  come in contact with each other. 
     In this case, a spaced interval C 12  between the central line of the line width of the embedded coil pattern  2131  and the central line of the line width of the conductor layer  2132  may be adjusted by those skilled in the art within a suitable error range. 
     Third Exemplary Embodiment 
       FIG. 5  is a cross-sectional view of a coil component  300  according to a third exemplary embodiment. In the coil component  300  according to the third exemplary embodiment, a line width W 1  of an embedded coil pattern of a coil  313  embedded in a support member  312  may be greater than a line width W 2  of a conductor layer of the coil disposed on the embedded coil pattern. Since the line width of the embedded coil pattern is relatively greater than that of the conductor layer, a seed layer serving as a base of the conductor layer having a fine pitch may have a wide line width, such that even though a process error occurs at the time of adjusting alignment through exposure and development of an insulator, a risk of an open failure, or the like, may be decreased. Further, when the line width of the embedded coil pattern is relatively greater than that of the conductor layer, at the time of removing the insulator using a CO 2  laser, the embedded coil pattern may attenuate an output of the CO 2  laser to prevent a support member from being damaged by the laser. As a result, a defect that the coil is delaminated from the support member, or the like, may be prevented. 
     Fourth Exemplary Embodiment 
       FIG. 6  is a cross-sectional view of a coil component  400  according to a fourth exemplary embodiment in the present disclosure. In the coil component  400  according to the fourth exemplary embodiment, a line width W 3  of an embedded coil pattern of a coil  413  embedded in a support member  412  is smaller than a line width W 4  of a conductor layer of the coil  413  disposed on the embedded coil pattern. In this case, a fine pitch of the embedded coil pattern may be implemented enough to further decrease the line width of the embedded coil pattern. As a result, this structure is advantageous for significantly increasing the entire number of turns of the coil pattern. The number of turns of the coil pattern may be increased by decreasing the line width of the embedded coil pattern, and the line width of the conductor layer disposed thereon may be relatively wide, such that this structure is advantageous for decreasing side effects such as breakage of the conductor layer at the time of increasing a thickness of the conductor layer, and the like. 
     Fifth Exemplary Embodiment 
       FIG. 7  is a cross-sectional view of a coil component  500  according to a fifth exemplary embodiment in the present disclosure. The coil component  500  according to the fifth exemplary embodiment may be different from the coil component  100  according to the first exemplary embodiment in that a thin film conductor layer  5133  is interposed between an embedded coil pattern  5131  and a conductor layer  5132 . The thin film conductor layer  5133  may have preferably a nano-scale thickness, and more preferably, 50 nm or more to 1 μm or less. A side surface of the thin film conductor layer  5133  may directly contact with an insulating layer  14  enclosing the conductor layer  5132 . A side surface of a via hole V may be enclosed by the thin film conductor layer  5133 , and a center of the via hole V may be filled with the conductor layer  5132 . A specific method of forming the thin film conductor layer  5133  is not limited, but it is suitable to use a metal sputtering method in order to uniformly form the thin film conductor layer  5133  having a thin thickness. As a result, since even a material which is slightly restrictively used in a chemical copper plating method, or the like, may be included in examples of a material forming the thin film conductor layer  5133 , a degree of freedom in selecting the material may be relatively increased. For example, the thin film conductor layer  5133  may contain one or more of Mo, Ti, Ni, Al, and W, but is not limited thereto. The thin film conductor layer  5133  may be added before the insulator is laminated in the manufacturing method described in  FIGS. 3A through 3I . The thin film conductor layer  5133  may be patterned by removing a thin film conductor layer except for a thin film conductor layer coming in contact with a lower surface of the conductor layer at the time of removing an insulator using a laser after integrally forming the thin film conductor layer on an upper surface of the embedded coil pattern  5131  prepared in advance as well as upper and lower surfaces of a support member  512  and forming all the conductor layers  5132 . The thin film conductor layer  5133  may serve to increase close adhesion between the insulator and the support member in a manufacturing process of the coil component. Since in a case of patterning the insulator, an aspect of the patterned insulator is increased substantially to about 20 or so, a leaning defect or delamination phenomenon of the patterned insulator may occur. Therefore, a risk of delamination of the insulator or occurrence of a short-circuit due to delamination may be removed by forming the thin film conductor layer in advance before laminating the insulator to increase close adhesion between the insulator and the support member. Further, since a CO 2  laser does not pass through the insulator to thereby be directly irradiated to the support member, but arrives earlier at the thin film conductor layer, output of the CO 2  laser may be attenuated, such that damage of the support member may be prevented. 
     Sixth Exemplary Embodiment 
       FIG. 8  is a cross-sectional view of a coil component  600  according to a sixth exemplary embodiment in the present disclosure. The coil component  600  according to the sixth exemplary embodiment may be different from the coil component  200  according to the second exemplary embodiment in that a thin film conductor layer  6133  is interposed between an embedded coil pattern  6131  embedded in a support member  612  and a conductor layer  6132 . A description of the coil component  200  according to the second exemplary embodiment may be applied to the coil component  600  as it is, and a description of an effect exhibited by interposing the thin film conductor layer, for example, an effect of preventing delamination of an insulator, or the like, may be applied to the coil component  600  as it is. Since close adhesion between the thin film conductor layer and the insulator is excellent, at the time of removing the insulator using a laser, the thin film conductor layer adhered below the insulator may also be easily removed together. 
     Seventh Exemplary Embodiment 
       FIG. 9  is a cross-sectional view of a coil component  700  according to a seventh exemplary embodiment in the present disclosure. The coil component  700  according to the seventh exemplary embodiment is different from the coil component  300  according to the third exemplary embodiment in that a thin film conductor layer  7133  is interposed between an embedded coil pattern  7131  embedded in a support member  712  and a conductor layer  7132 , but since the coil component  700  includes configurations overlapping those in the coil component  300 , a detailed description thereof will be omitted. 
     Eighth Exemplary Embodiment 
       FIG. 10  is a cross-sectional view of a coil component  800  according to an eighth exemplary embodiment in the present disclosure. The coil component  800  according to the eighth exemplary embodiment is different from the coil component  400  according to the fourth exemplary embodiment in that a thin film conductor layer  8133  is interposed between an embedded coil pattern  8131  embedded in a support member  812  and a conductor layer  8132 , but since the coil component  800  includes configurations overlapping those in the coil component  400 , a detailed description thereof will be omitted. 
     With the above-mentioned coil component, a degree of freedom in alignment may be increased as compared to a seed layer protruding from one surface and the other surface of the support member by allowing the embedded coil pattern corresponding to the seed layer to be embedded from one surface and the other surface of the support member. As a result, a problem such as a short-circuit defect due to eccentricity capable of occurring in exposure and development of the insulator, a limitation in ultra-fine patterning, or the like, may be solved. Further, the embedded coil pattern, which is a portion of the coil, may be embedded from one surface and the other surface of the support member, such that a thickness of the entire coil component may be decreased at the time of implementing the same thickness of the coil, which is advantageous for providing a low-profile coil component. Further, since the aspect ratio of the coil is increased based on a coil component having the same thickness, electric properties such as Rdc, and the like, may be excellent, and as a thickness of the insulating layer is decreased by embedding the seed layer, a path of a magnetic flux may be decreased and a filling thickness of the magnetic material on and below the coil may be increased, such that a DC-bias effect may be improved due to an increase in inductance and a decrease in magnetic flux density. 
     As set forth above, according to exemplary embodiments in the present disclosure, the coil component of which Rdc characteristics are improved by significantly increasing the thickness of the coil pattern and allowing the coil pattern to have a fine line width within a restricted size of the coil component may be provided. 
     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.