Patent Publication Number: US-9852842-B2

Title: Coil electronic component

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority and benefit of Korean Patent Application No. 10-2015-0076403 filed on May 29, 2015, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     The present disclosure relates to a coil electronic component and a method of manufacturing the same. 
     An inductor, an electronic component, is a representative passive element that is commonly used in electronic circuits together with a resistor and a capacitor to remove noise. 
     An inductor may be manufactured by forming internal coil parts, then forming a body in which the internal coil parts are embedded. End portions of the internal coil parts can be exposed, and external electrodes formed on external portions of the body. 
     SUMMARY 
     An inductor body may be formed of a magnetic material-resin composite in which the magnetic material and the resin are mixed with each other, and characteristics of the inductor may be controlled depending on characteristics of the magnetic material included in the inductor body. 
     An aspect of the present disclosure may provide a coil electronic component capable of being used in a high frequency band by using magnetic particles each having a significantly reduced size, and a method of manufacturing the same. 
     According to an aspect of the present disclosure, a coil electronic component includes a body having a coil part disposed therein, and external electrodes connected to the coil part. The body includes magnetic particles each having a small size to reduce eddy current loss. A method of manufacturing the coil electronic component is also provided. 
     Meanwhile, a particle size distribution D 50  of the magnetic particles may be 1 μm or less. 
     According to another aspect of the present disclosure, a coil electronic component may include a body having a coil part embedded therein. The body includes magnetic particles having a particle size of 1 μm or less, and a variation coefficient of the particle size of the magnetic particles in the body is 20% or less. 
     In a further aspect of the present disclosure, a coil electronic component may include a coil part having a hole penetrating through a center thereof, and a body enclosing the coil part and extending through the hole at the center of the coil part. The body includes magnetic particles dispersed in a thermosetting resin, and a particle size distribution ratio D 99 /D 50  of the magnetic particles included in the body is 1.5 or less. 
    
    
     
       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 illustrating a coil electronic component according to an exemplary embodiment in the present disclosure; 
         FIG. 2  is a cross-sectional view taken along line A-A′ of  FIG. 1 ; 
         FIG. 3  is an enlarged view of a region P of  FIG. 2 ; 
         FIG. 4  is a flow chart illustrating a method of manufacturing a coil electronic component according to an exemplary embodiment in the present disclosure; 
         FIGS. 5A through 5D  are views illustrating sequential steps of the method of manufacturing the coil electronic component according to an exemplary embodiment in the present disclosure; and 
         FIG. 6  is a graph illustrating results obtained by measuring Q values of coil electronic components having different sizes of magnetic particles. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. 
     The disclosure may, however, be embodied in many different forms and should not be construed as being limited to the 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. 
     In the drawings, the shapes and dimensions of elements may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements. 
     Hereinafter, a coil electronic component according to an exemplary embodiment will be described. Particularly, an inductor will be described, but the present disclosure is not limited thereto. 
       FIG. 1  is a schematic perspective view illustrating a coil electronic component according to an exemplary embodiment in which a coil part disposed in the coil electronic component is visible, and  FIG. 2  is a cross-sectional view taken along line A-A′ of  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , the inductor used in a power line of a power supply circuit is illustrated as one example of the coil electronic component. However, the coil electronic component according to an exemplary embodiment may be appropriately utilized as beads, a filter, and the like, in addition to the inductor. 
     The coil electronic component  100  may include a body  50  and external electrodes  80 , wherein the body  50  may include a coil part  40  including a substrate layer  20  and coil patterns  41  and  42 . 
     The body  50  may have an approximately hexahedral shape, and L, W, and T illustrated in  FIG. 1  refer to a length direction, a width direction, and a thickness direction, respectively. 
     The body  50  may include first and second surfaces opposing each other in the thickness direction, third and fourth surfaces opposing each other in the length direction, and fifth and sixth surfaces opposing each other in the width direction. The body  50  may have a rectangular parallelepiped shape in which a dimension thereof in the length direction (i.e., a length) is larger than a dimension thereof in the width direction (i.e., a width). 
     The body  50  may form an appearance of the coil electronic component  100  and may be formed of a magnetic material having magnetic properties. 
     The magnetic material may have a powder form and may be included in the body  50  by being dispersed in a polymer such as an epoxy resin, polyimide, or the like. 
     As illustrated in  FIG. 2 , the coil part  40  may be disposed in the body  50 . The coil part  40  may include the substrate layer  20  and the coil patterns  41  and  42  disposed on at least one surface of the substrate layer  20 . The coil patterns  41  and  42  may alternatively be disposed on respective opposing surfaces of the substrate layer  20 . 
     The substrate layer  20  may include, for example, polypropylene glycol (PPG), ferrite, a metal-based soft magnetic material, or the like. 
     A through hole may be formed in a central portion of the substrate layer  20 , and may be filled with the magnetic material included in the body  50  to form a core part  55 . The core part  55  may be formed by filling the through hole with the magnetic material, thereby improving or increasing an inductance (L) value of the inductor. 
     A first coil pattern  41  having a coil shape may be formed on one surface of the substrate layer  20 , and a second coil pattern  42  having a coil shape may be formed on another surface of the substrate layer  20  opposing the one surface of the substrate layer  20 . 
     The coil patterns  41  and  42  may be formed to have spiral shapes, and the first and second coil patterns  41  and  42  formed on one surface and the other surface of the substrate layer  20 , respectively, may be electrically connected to each other though a via electrode (not illustrated) formed in and penetrating through the substrate layer  20 . 
     One end portion of the first coil pattern  41  disposed on one surface of the substrate layer  20  may be exposed to one external surface of the body  50  in the length direction, and one end portion of the second coil pattern  42  disposed on the other surface of the substrate layer  20  may be exposed to the other external surface of the body  50  in the length direction. 
     The external electrodes  80  may be formed on both surfaces of the body  50  in the length direction so as to be connected to the exposed end portions of the coil patterns  41  and  42  respectively. The coil patterns  41  and  42 , the via electrode (not illustrated), and the external electrodes  80  may be formed of a metal having excellent electrical conductivity, such as silver (Ag), copper (Cu), nickel (Ni), aluminum (Al), alloys thereof, or the like. 
     According to an exemplary embodiment, the coil patterns  41  and  42  may be covered with an insulation layer  30 . 
     The insulation layer  30  may be formed by a method known in the art, such as a screen printing method, an exposure and development method of a photo resist (PR), a spray application method, or the like. The coil patterns  41  and  42  may be covered with the insulation layer  30  so as not to be in direct contact with the magnetic material included in the body  50 . 
       FIG. 3  is an enlarged view of a region P of  FIG. 2 . 
     Referring to  FIGS. 2 and 3 , the body  50  may include magnetic material having magnetic properties, and as illustrated in  FIG. 3 , the magnetic material may have a plurality of magnetic particles  51  dispersed in a thermosetting resin  52  such as an epoxy resin, polyimide, or the like. 
     The body  50  may include the magnetic particles  51  having a particle size of 1 μm or less. 
     According to an exemplary embodiment, a particle diameter of the magnetic particles  51  may be measured by cutting an inductor body, observing a fraction of the surface obtained by the cutting with a scanning electron microscope (SEM), and analyzing an image obtained by SEM. 
     Specifically, a particle size distribution D 50  of the magnetic particles included in the body  50  may be 1 μm or less. 
     The particle size of the magnetic particles included in the body  50  may be 1 μm or less on the basis of D 50 , and thus 50% or more of the magnetic particles included in the body  50  may have a size (e.g., a diameter) of 1 μm or less. This particle size distribution provides a coil electronic component that has reduced eddy current loss, and that may be used in a high frequency band. 
     According to an exemplary embodiment, more preferably, a particle size distribution D 99  of the magnetic particles included in the body  50  may be 1 μm or less. 
     The particle size of the magnetic particles included in the body  50  may be 1 μm or less on the basis of D 99 , whereby the coil electronic component manufactured therefrom may have significantly reduced eddy current loss, and may be used even in a frequency band of approximately 100 MHz. 
     In addition, the body  50  may include the magnetic particles having the particle size of 1 μm or less, and the particle size distribution ratio D 99 /D 50  of the magnetic particles included in the body may be 1.5 or less. 
     The particle size distribution D 50  of the magnetic particles included in the body  50  may be 1 μm or less, and at the same time, a particle size distribution ratio D 99 /D 50  of the magnetic particles included in the body may be 1.5 or less. 
     As described above, when the body  50  includes the magnetic particles having a particle size of 1 μm or less, and the particle size distribution ratio D 99 /D 50  of the magnetic particles is 1.5 or less, a size of the particles may be significantly reduced, and may be uniformly controlled to form a resonant frequency in a high frequency region. 
     More preferably, a particle size distribution ratio D 99.9 /D 50  of the magnetic particles included in the body  50  may be 1.5 or less. 
     According to an exemplary embodiment, the body  50  may include the magnetic particles having a particle size of 1 μm or less, and a variation coefficient to the particle size of the magnetic particles included in the body  50  may be 20% or less. 
     The variation coefficient is a percentage obtained by dividing a deviation of particle size of magnetic particles included in the body into an average of the particle size of the magnetic particles. (Variation coefficient to particle size of magnetic particles=(deviation of particle size of magnetic particles/average of the particle size of the magnetic particles)×100%) 
     When the body  50  includes the magnetic particles having the particle size of 1 μm or less, and the variation coefficient to the particle size of the magnetic particles included in the body is 20% or less, the size of the particles may be significantly reduced, and may be uniformly controlled, thereby uniformly implementing transmittance. 
     In addition, the particle size distribution D 50  of the magnetic particles included in the body  50  may be 1 μm or less, and at the same time, the variation coefficient to the particle size of the magnetic particles included in the body may be 20% or less. 
     More preferably, the particle size distribution D 99  of the magnetic particles included in the body  50  may be 1 μm or less, and at the same time, the variation coefficient to the particle size of the magnetic particles included in the body may be 20% or less. 
     The particle size distribution and the variation coefficient of the magnetic particles may be measured by cutting an inductor body, observing a fraction of a surface obtained by the cutting with a scanning electron microscope (SEM), and analyzing an image obtained by the SEM, wherein at least 2000 magnetic particles may be observed on the obtained SEM image. 
     Meanwhile, the magnetic particles  51  may be formed of a magnetic metal material, and in this case, an electronic component may be provided that satisfies a high direct current (DC)-bias characteristic due to high saturation magnetization values of the magnetic metal material while simultaneously being usable in a high frequency band. 
     Meanwhile, the magnetic particles may include an amorphous magnetic metal material. 
     The amorphous magnetic metal material may be an Fe—B—P-based magnetic material, and may include 88 to 92 mol % of iron (Fe), 6 to 9 mol % of boron (B), and 1 to 2 mol % of phosphorus (P). 
     According to an exemplary embodiment, the magnetic particles may include the amorphous magnetic metal material including 88 to 92 mol % of iron (Fe), 6 to 9 mol % of boron (B), and 1 to 2 mol % of phosphorus (P). In such an exemplary embodiment, a separate seed may not be required for securing uniformity of the magnetic particles when the magnetic particles are formed. Accordingly, platinum (Pt), which is a general component of the seed, may not be included, and thus manufacturing cost of the magnetic particles may be reduced, and a manufacturing process of the magnetic particles may be simplified. 
     In the amorphous magnetic metal material, when a content of iron (Fe) is less than 88 mol %, a saturation magnetization value of the material may be decreased, and when the content of iron (Fe) is more than 92 mol %, a crystalline shape may be included. It may therefore be desirable to include 88 to 92 mol % of iron (Fe) in the amorphous magnetic metal material. 
     In the amorphous magnetic metal material, when a content of boron (B) is less than 6 mol %, the crystalline shape may be included, and when the content of boron (B) is more than 9 mol %, a saturation magnetization value of the material may be decreased. It may therefore be desirable to include 6 to 9 mol % of boron (B) in the amorphous magnetic metal material. 
     In the amorphous magnetic metal material, when a content of phosphorus (P) is less than 1 mol %, the crystalline shape may be included, and when a content of phosphorus (P) is more than 2 mol %, the saturation magnetization value of the material may be decreased. It may therefore be desirable to include 1 to 2 mol % of phosphorus (P) in the amorphous magnetic metal material. 
     The magnetic particles may be formed by a liquid phase reduction method. 
     For example, the magnetic particles may be formed by dissolving a metal salt in a liquid and adding a liquid reducing agent to reduce and deposit metal ions. Here, a size of the magnetic particles may be controlled by a difference in reaction rate according to the addition of the reducing agent. 
     According to an exemplary embodiment, the coil electronic component may include the body  50  including the magnetic particles having D 50  of 1 μm or less to reduce eddy current loss, thereby being used in a high frequency band. 
     In addition, according to an exemplary embodiment, the coil electronic component may maintain high Q values at the high frequency band, for example, a frequency region at which Q factor is maintained to be 60 or more may be 5 MHz to 100 MHz, and thus the coil electronic component may be used in a wide frequency region. 
     Method of Manufacturing Electronic Component 
       FIG. 4  is a flow chart illustrating a method of manufacturing a coil electronic component according to an exemplary embodiment, and  FIGS. 5A through 5D  are views illustrating sequential steps of the method of manufacturing the coil electronic component according to an exemplary embodiment. 
     Referring to  FIG. 4 , the method of manufacturing the coil electronic component according to an exemplary embodiment may include forming coil patterns on at least one surface of a substrate layer (S 1 ), and forming a body by disposing magnetic layers on upper and lower portions of the substrate layer (S 2 ). The body may be formed by stacking and pressing magnetic layers on upper and lower surfaces of the substrate layer having the coil patterns on at least one surface thereof. 
     Meanwhile, the method of manufacturing the coil electronic component according to an exemplary embodiment may further include, after the forming of the body, forming external electrodes on an external surface of the body (S 3 ). The external electrodes may be formed so as to each be electrically connected to a respective end of the coil patterns. 
     Referring to  FIG. 5A , a material of the substrate layer  20  is not specifically limited, and for example, may include polypropylene glycol (PPG), ferrite, a metal-based soft magnetic material, or the like. The substrate layer may have a thickness of 40 μm to 100 μm. 
     Although not illustrated in the drawings, the forming of the coil patterns  41  and  42  may include forming a plating resist on the substrate layer  20 , the plating resist having an opening part for forming coil patterns. The plating resist, which is a general photosensitive resist film, may be a dry film resist, or the like, but the exemplary embodiment is not specifically limited thereto. In general, the plating resist may be formed on the substrate layer  20  prior to forming of the coil patterns  41  and  42 . 
     The coil patterns  41  and  42  may be formed by filling the opening part for forming the coil patterns with an electroconductive metal using electroplating, and the like. 
     The coil patterns  41  and  42  may be formed of a metal having excellent electrical conductivity. For example, the coil patterns  41  and  42  may be formed of silver (Ag), palladium (Pd), aluminum (Al), nickel (Ni), titanium (Ti), gold (Au), copper (Cu), platinum (Pt), alloys thereof, or the like. 
     Although not illustrated, after the forming of the coil patterns  41  and  42 , the plating resist may be removed by chemical etching, and the like. 
     When the plating resist is removed, the coil patterns  41  and  42  may be left on the substrate layer  20  as illustrated in  FIG. 5A . 
     A via electrode (not illustrated) may be formed by forming a hole in a portion of the substrate layer  20  and providing a conductive material therein, and the coil patterns  41  and  42  formed on one surface of the substrate layer  20  and the other surface thereof may be electrically connected to each other through the via electrode. The coil patterns  41  and  42  may be electrically connected to each other in series. 
     A hole  55 ′ penetrating through the substrate layer  20  may be formed in a central portion of the substrate layer  20  by a drilling method, a laser, sand blasting, punching, or the like. The hole  55 ′ can be formed prior to or after the forming of the coil patterns  41  and  42  on the substrate layer  20 . 
     As illustrated in  FIG. 5B , after the coil patterns  41  and  42  are formed, an insulation layer  30  covering the coil patterns  41  and  42  may be selectively formed. The insulation layer  30  may be formed by a method known in the art such as a screen printing method, an exposure and development method of a photo resist (PR), a spray application method, or the like, but the forming method of the insulation layer is not limited thereto. 
     Next, as illustrated in  FIG. 5C , the body  50  may be formed by disposing the magnetic layers on upper and lower portions of the substrate layer  20  on which the coil patterns  41  and  42  are formed. 
     The body  50  may be formed by stacking the magnetic layers on both surfaces of the substrate layer  20  and pressing the stacked magnetic layers by a lamination method or an isostatic pressing method. In this case, a core part  55  may be formed by filling the hole  55 ′ with magnetic material. The body  50  may be formed to substantially enclose the coil patterns  41  and  42  with the exception of ends of the coil patterns  41  and  42  which may remain exposed. 
     Here, the magnetic layers may be formed of a magnetic paste composition for a coil electronic component. The magnetic paste composition for the coil electronic component includes magnetic particles included in the body of the coil electronic component according to an exemplary embodiment as described above. 
     The magnetic layer may include a plurality of magnetic particles, and a particle size distribution D 50  of the magnetic particles included in the magnetic layer may be 1 μm or less. 
     More preferably, a particle size distribution D 99  of the magnetic particles included in the magnetic layer may be 1 μm or less. 
     In addition, the magnetic layer may include magnetic particles having a particle size of 1 μm or less, and a particle size distribution D 99 /D 50  of the magnetic particles included in the magnetic layer may be 1.5 or less. 
     The particle size distribution D 50  of the magnetic particles included in the magnetic layer may be 1 μm or less, and the particle size distribution ratio D 99 /D 50  thereof may be 1.5 or less. 
     More preferably, a particle size distribution ratio D 99.9 /D 50  of the magnetic particles included in the magnetic layer may be 1.5 or less. 
     According to an exemplary embodiment, the magnetic layer may include magnetic particles having a particle size of 1 μm or less, and a variation coefficient to the particle size of the magnetic particles included in the body may be 20% or less. 
     The particle size distribution D 50  of the magnetic particles included in the magnetic layer may be 1 μm or less, and a variation coefficient to the particle size of the magnetic particles included in the magnetic layer may be 20% or less. 
     More preferably, the particle size distribution D 99  of the magnetic particles included in the magnetic layer may be 1 μm or less, and a variation coefficient to the particle size of the magnetic particles included in the magnetic layer may be 20% or less. 
     Meanwhile, the magnetic particles may include an amorphous magnetic metal material. 
     The amorphous magnetic metal material may be an Fe—B—P-based magnetic material, and may include 88 to 92 mol % of iron (Fe), 6 to 9 mol % of boron (B), and 1 to 2 mol % of phosphorus (P). 
     Since a description of the method of manufacturing the coil electronic component according to an exemplary embodiment is the same as that of the above-described magnetic particles included in the coil electronic component, a detailed description of the method of manufacturing the coil electronic component will be omitted to avoid an overlapping description. 
     Next, as illustrated in  FIG. 5D , external electrodes  80  may be formed to be connected to end portions of the coil patterns  41  and  42  exposed to at least one surface of the body  50 . 
     The external electrodes  80  may be formed using a paste containing a metal having excellent electric conductivity, wherein the paste may be a conductive paste containing, for example, nickel (Ni), copper (Cu), tin (Sn), or silver (Ag) alone, or alloys thereof. The external electrodes  80  may be formed by a dipping method, or the like, as well as a printing method depending on a shape thereof. 
     Portions of the method of manufacturing the coil electronic component the same as those of the above-described coil electronic component according to an exemplary embodiment will be omitted herein to avoid an overlapping description. 
     Experimental Example 
     The coil electronic component used in the present experiment was manufactured as follows. 
     Toroidal cores each having an external diameter of 2 cm, a height of 0.4 cm, and a width of 0.35 cm were manufactured by mixing magnetic particles with a resin. Multiple toroidal cores were prepared with different magnetic particle distributions, the magnetic particles satisfying conditions shown in Tables 1, 2, and 3 below, and the toroidal cores were evaluated. 
     Table 1 below shows Q values at 100 MHz depending on D 50  of the magnetic particles included in the body of the coil electronic component. 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 D 50   
                 Q values at 
               
               
                 Samples 
                 (μm) 
                 100 MHz 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 1 
                 0.5 
                 60 
               
               
                 2 
                 1.0 
                 30 
               
               
                 3 
                 3.0 
                 20 
               
               
                 4 
                 6.0 
                 10 
               
               
                   
               
            
           
         
       
     
     As shown in Table 1 above, it can be confirmed that the Q values at 100 MHz of samples 1 and 2 having D 50  of 1 μm or less are 30 or more, but the Q values at 100 MHz of samples 3 and 4 having D 50  of more than 1 μm are 20 or less. 
     Table 2 below shows resonant frequency values depending on D 99 /D 50  particle size distribution ratio when D 50  of the magnetic particles included in the body of the coil electronic component is about 1 μm. 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                 Resonant 
               
               
                   
                   
                 Frequency 
               
               
                 Samples 
                 D 99 /D 50   
                 (MHz) 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 5 
                 1.3 
                 230 
               
               
                 6 
                 1.5 
                 210 
               
               
                 7 
                 2 
                 180 
               
               
                 8 
                 5 
                 150 
               
               
                 9 
                 10 
                 80 
               
               
                   
               
            
           
         
       
     
     As shown in Table 2 above, the resonant frequency values of samples 5 and 6 having D 99 /D 50  of 1.5 or less are 200 MHz or more. However, samples 7 to 9 having D 99 /D 50  of more than 1.5 have lower resonant frequency values of 180 MHz or less. 
     Table 3 below shows transmittance depending on variation coefficient values when D 50  of the magnetic particles included in the body of the coil electronic component is approximately 1 μm. 
     
       
         
           
               
               
               
             
               
                 TABLE 3 
               
               
                   
               
               
                   
                 Variation 
                   
               
               
                   
                 Coefficient 
               
               
                 Samples 
                 (%) 
                 Transmittance 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                 10 
                 10 
                 9 
               
               
                 11 
                 15 
                 10 
               
               
                 12 
                 20 
                 12 
               
               
                 13 
                 30 
                 15 
               
               
                 14 
                 50 
                 19 
               
               
                   
               
            
           
         
       
     
     As shown in Table 3 above, samples 13 and 14 having the variation coefficient values of more than 20% have high transmittance values (15 or more) and therefore exhibit lower resonant frequency values. In contrast, samples 10, 11, and 12 having variation coefficient values of 20% or less advantageously have transmittance values of 12 or less. 
       FIG. 6  is a graph or plot illustrating results obtained by measuring Q values of coil electronic components as a function of frequency, wherein the coil electronic components were formed by having each body include magnetic particles having a size of (or D 50  particle size distribution of) 0.8 μm, 2 μm, 3.5 μm, 14 μm, or 20 μm, respectively. 
     As illustrated in  FIG. 6 , it can be confirmed that when D 50  was 1 μm or less (0.8 μm), high Q values are provided in a wide frequency band. In contrast, Q values are generally lower for examples including larger magnetic particle sizes. 
     As set forth above, according to exemplary embodiments, the coil electronic component is provided that is capable of being used in a high frequency band by reducing eddy current loss. A method of manufacturing the coil electronic component is also 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 disclosure as defined by the appended claims.