Patent Publication Number: US-8970336-B2

Title: Method of manufacturing an electronic component

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of International Application No. PCT/JP2010/058449 filed May 19, 2010, which claims priority to Japanese Patent Application No. 2009-149243 filed Jun. 24, 2009, the entire contents of each of these applications being incorporated herein by reference in their entirety. 
    
    
     TECHNICAL FIELD 
     The present invention relates to electronic components and method of manufacturing the same and particularly relates to an electronic component including a coil and a method of manufacturing the same. 
     BACKGROUND 
     Conventional electronic components known as open magnetic circuit-type laminated coil components are disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2005-259774 (Patent Literature 1).  FIG. 8  is a sectional view of an open magnetic circuit-type laminated coil component  500  disclosed in Patent Literature 1. 
     As shown in  FIG. 8 , the open magnetic circuit-type laminated coil component  500  includes a laminate  502  and a coil L. The laminate  502  is composed of a plurality of laminated magnetic layers. The coil L has a spiral shape and includes a plurality of coil conductors  506  connected to each other. The open magnetic circuit-type laminated coil component  500  further includes a non-magnetic layer  504 . The non-magnetic layer  504  is placed in the laminate  502  so as to cross the coil L. 
     In the open magnetic circuit-type laminated coil component  500 , a magnetic flux φ 500  surrounding the coil conductors  506  passes through the non-magnetic layer  504 . This prevents the occurrence of magnetic saturation due to the excessive concentration of the magnetic flux in the laminate  502 . Therefore, the open magnetic circuit-type laminated coil component  500  has excellent direct current superposition characteristics. 
     SUMMARY 
     The present disclosure provides an electronic component capable of preventing the occurrence of magnetic saturation due to a magnetic flux surrounding each coil conductor and a method of manufacturing the electronic component. 
     In one aspect of the disclosure, a method of manufacturing an electronic component includes steps of forming a laminate and calcining the laminate. The laminate includes a spiral coil including a plurality of connected coil conductors overlapping each other in plan view in a stacking direction, and a plurality of continuously stacked unit layers. Each of the unit layers includes a first insulating layer overlaid with one of the coil conductors and a second insulating layer having a greater Ni content than the first insulating layer. Each of the second insulting layers of the first unit layers is provided on portions of the first insulating layer other than where the one coil conductor is formed. 
     In another aspect of the disclosure, an electronic component includes a plurality of unit layers. Each of the unit layers include a single sheet-shaped first insulating layer, a coil conductor on the first insulating layer, and a second insulating layer on a portion of the first insulating layer other than where the coil conductor is provided. The unit layers are continuously stacked such that the coil conductors are connected to each other to form a spiral coil. The first insulating layers include first portions sandwiched between the coil conductors in the stacking direction and second portions other than the first portions. The first portions have a Ni content lower than a Ni content of the second portions. The Ni content of the second portions is lower than a Ni content of the second insulating layers. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of an electronic component according to an exemplary embodiment. 
         FIG. 2  is an exploded perspective view of a laminate included in an electronic component according to the embodiment. 
         FIG. 3  is a sectional view of the electronic component taken along the line A-A of  FIG. 1 . 
         FIG. 4  is a graph showing simulation results. 
         FIG. 5  is a structural sectional view of an electronic component according to a first exemplary modification. 
         FIG. 6  is a structural sectional view of an electronic component according to a second exemplary modification. 
         FIG. 7  is a structural sectional view of an electronic component according to a third exemplary modification. 
         FIG. 8  is a sectional view of an open magnetic circuit-type laminated coil component disclosed in Patent Literature 1. 
     
    
    
     DETAILED DESCRIPTION 
     The inventor realized that in the open magnetic circuit-type laminated coil component  500 , a magnetic flux φ 502  surrounding each coil conductor  506  is present in addition to the magnetic flux φ 500  surrounding the coil conductors  506 . The magnetic flux φ 502  causes magnetic saturation in the open magnetic circuit-type laminated coil component  500 . 
     Electronic components according to exemplary embodiments of the disclosure, which are capable of preventing the occurrence of magnetic saturation due to a magnetic flux surrounding each coil conductor, and methods of manufacturing the electronic components, will now be described. 
     An electronic component according to an exemplary embodiment is described below with reference to  FIGS. 1-3 .  FIG. 1  is a perspective view of electronic components  10   a  to  10   d  according to embodiments.  FIG. 2  is an exploded perspective view of a laminate  12   a  included in the electronic component  10   a  according to an embodiment.  FIG. 3  is a structural sectional view of the electronic component  10   a  taken along the line A-A of  FIG. 1 . The laminate  12   a  shown in  FIG. 2  is in an uncalcined state. The electronic component  10   a  shown in  FIG. 3  is in a calcined state calcination. Hereinafter, the stacking direction of the electronic component  10   a  is defined as a z-axis direction, a direction along a long side of the electronic component  10   a  is defined as an x-axis direction, and a direction along a short side of the electronic component  10   a  is defined as a y-axis direction. The x-axis, y-axis, and z-axis are orthogonal to each other. 
     With reference to  FIG. 1 , the electronic component  10   a  includes the laminate  12   a  and external electrodes  14   a  and  14   b . The laminate  12   a  has a rectangular parallelepiped shape and includes a coil L (not explicitly shown in  FIG. 1 ). The external electrodes  14   a  and  14   b  are electrically connected to the coil L and are each arranged on a corresponding one of side surfaces of the laminate  12   a  that are opposed to each other. In this embodiment, the external electrodes  14   a  and  14   b  are arranged to cover the two side surfaces, which are located at both ends of the component in the x-axis direction. 
     As shown in  FIG. 2 , the laminate  12   a  is composed of insulating layers  15   a  to  15   e ,  16   a  to  16   g , and  19   a  to  19   g ; coil conductors  18   a  to  18   g ; and via-hole conductors b 1  to b 6 . Each of the insulating layers  15   a  to  15   e  has a rectangular shape and is a single sheet-shaped magnetic layer made of Ni—Cu—Zn ferrite. The insulating layers  15   a  to  15   c  are stacked in that order on the positive side of a region containing the coil conductors  18   a  to  18   g  in the z-axis direction and form a covering. The insulating layers  15   d  and  15   e  are stacked in that order on the negative side of the region containing the coil conductors  18   a  to  18   g  in the z-axis direction and form another covering. 
     As shown in  FIG. 2 , the insulating layers  19   a  to  19   g  are rectangular and have a first Ni content. In this embodiment, the insulating layers  19   a  to  19   g  are non-magnetic layers made of Cu—Zn ferrite containing no Ni. The uncalcined insulating layers  19   a  to  19   g  are non-magnetic; however, the calcined insulating layers  19   a  to  19   g  are partly magnetic. This is described below. 
     As shown in  FIG. 2 , the coil conductors  18   a  to  18   g  are made of a conductive material containing Ag, have a length equal to a ¾ turn, and form the coil L together with the via-hole conductors b 1  to b 6 . The coil conductors  18   a  to  18   g  are each arranged on a corresponding one of the insulating layers  19   a  to  19   g . One end of the coil conductor  18   a  is exposed on a side of the insulating layer  19   a  that is located on a negative side of the insulating layer in the x-axis direction and serves as a lead conductor. This end of the coil conductor  18   a  is connected to the external electrode  14   a  shown in  FIG. 1 . One end of the coil conductor  18   g  is exposed on the positive side of the insulating layer  19   g  in the x-axis direction and serves as a lead conductor. This end of the coil conductor  18   g  is connected to the external electrode  14   b  shown in  FIG. 1 . The coil conductors  18   a  to  18   g  overlap each other to form a single rectangular ring in plan view in the z-axis direction. 
     As shown in  FIG. 2 , the via-hole conductors b 1  to b 6  extend through the insulating layers  19   a  to  19   f  in the z-axis direction and connect the coil conductors  18   a  to  18   g  neighboring each other in the z-axis direction. In particular, the via-hole conductor b 1  connects the other end of the coil conductor  18   a  to one end of the coil conductor  18   b . The via-hole conductor b 2  connects the other end of the coil conductor  18   b  to one end of the coil conductor  18   c . The via-hole conductor b 3  connects the other end of the coil conductor  18   c  to one end of the coil conductor  18   d . The via-hole conductor b 4  connects the other end of the coil conductor  18   d  to one end of the coil conductor  18   e . The via-hole conductor b 5  connects the other end of the coil conductor  18   e  to one end of the coil conductor  18   f . The via-hole conductor b 6  connects the other end of the coil conductor  18   f  to the other end of the coil conductor  18   g  (one end of the coil conductor  18   g  serves as a lead conductor, as described above). As described above, the coil conductors  18   a  to  18   g  and the via-hole conductors b 1  to b 6  form the coil L. The coil L has a coil axis extending in the z-axis direction and is spiral. 
     As shown in  FIG. 2 , the insulating layers  16   a  to  16   g  are arranged on portions of the insulating layers  19   a  to  19   g  other than the coil conductors  18   a  to  18   g . Therefore, principal surfaces of the insulating layers  19   a  to  19   g  are covered with the insulating layers  16   a  to  16   g  and the coil conductors  18   a  to  18   g . A principal surface of each of the insulating layers  16   a  to  16   g  and a principal surface of a corresponding one of the coil conductors  18   a  to  18   g  form a single plane and are flush with each other. The insulating layers  16   a  to  16   g  have a second Ni content higher than the first Ni content. In this embodiment, the insulating layers  16   a  to  16   g  are magnetic layers made of Ni—Cu—Zn ferrite. 
     The insulating layers  19   a  to  19   g  are thinner than the insulating layers  16   a  to  16   g . In particular, the insulating layers  19   a  to  19   g  have a thickness of 5 μm to 15 μm and the insulating layers  16   a  to  16   g  have a thickness of 25 μm. 
     The insulating layers  16   a  to  16   g  and  19   a  to  19   g  and coil conductors  18   a  to  18   g  configured as described above form unit layers  17   a  to  17   g . The unit layers  17   a  to  17   g  are continuously arranged between a group of the insulating layers  15   a  to  15   c  and a group of the insulating layers  15   d  and  15   e  in that order, thereby forming the laminate  12   a.    
     After the laminate  12   a  is calcined and the external electrodes  14   a  and  14   b  are formed thereon, the electronic component  10   a  has a cross-sectional structure as shown in  FIG. 3 . In particular, the Ni content of portions of the insulating layers  19   a  to  19   g  is increased to exceed the first Ni content during the calcination of the laminate  12   a . That is, during calcination the insulating layers  19   a  to  19   g  are partly transformed from non-magnetic layers to magnetic layers. 
     As shown in  FIG. 3  in detail, in the electronic component  10   a , the insulating layers  19   a  to  19   g  include first portions  20   a  to  20   f  and second portions  22   a  to  22   g . The first portions  20   a  to  20   f  correspond to portions of the insulating layers  19   a  to  19   f  that are sandwiched between the coil conductors  18   a  to  18   g  in the z-axis direction. In particular, the first portion  20   a  corresponds to a portion of the insulating layer  19   a  that is sandwiched between the coil conductors  18   a  and  18   b . The first portion  20   b  corresponds to a portion of the insulating layer  19   b  that is sandwiched between the coil conductors  18   b  and  18   c . The first portion  20   c  corresponds to a portion of the insulating layer  19   c  that is sandwiched between the coil conductors  18   c  and  18   d . The first portion  20   d  corresponds to a portion of the insulating layer  19   d  that is sandwiched between the coil conductors  18   d  and  18   e . The first portion  20   e  corresponds to a portion of the insulating layer  19   e  that is sandwiched between the coil conductors  18   e  and  18   f . The first portion  20   f  corresponds to a portion of the insulating layer  19   f  that is sandwiched between the coil conductors  18   f  and  18   g . The second portions  22   a  to  22   g  correspond to portions of the insulating layers  19   a  to  19   f  other than the first portions  20   a  to  20   f . However, no first portion (i.e., no portion “ 20   g ”) is present in the insulating layer  19   g , but the second portion  22   g  is present in that layer. This is because the insulating layer  19   g  is located on a more negative side in the z-axis direction as compared with the insulating layer  18   g , which is located on the most negative side in the z-axis direction. 
     The first portions  20   a  to  20   f  have a Ni content lower than the Ni content of the second portions  22   a  to  22   g . In this embodiment, the first portions  20   a  to  20   f  contain no Ni. Therefore, the first portions  20   a  to  20   f  are non-magnetic. In contrast, the second portions  22   a  to  22   g  contain Ni. Therefore, the second portions  22   a  to  22   g  are magnetic. The Ni content of the second portions  22   a  to  22   g  is lower than the Ni content of the insulating layers  16   a  to  16   g.    
     A method of manufacturing the electronic component  10   a  is now described below with reference to  FIG. 2 . In the method, the electronic component  10   a  is manufactured together with a plurality of electronic components  10   a  as described below. 
     Ceramic green sheets for forming the insulating layers  19   a  to  19   g  are prepared as shown in  FIG. 2 . In particular, raw materials are prepared by weighing ferric oxide (Fe 2 O 3 ), zinc oxide (ZnO), and copper oxide (CuO) at a predetermined ratio and are charged into a ball mill, followed by wet mixing. An obtained mixture is dried and is then pulverized. An obtained powder is calcined at 800° C. for one hour. The calcined powder is wet-pulverized in a ball mill, is dried, and is then disintegrated, whereby a ferrite ceramic powder is obtained. 
     The ferrite ceramic powder is mixed with a binder (vinyl acetate, a water-soluble acrylic resin, or the like), a plasticizer, a humectant, and a dispersant in a ball mill, followed by defoaming under reduced pressure. An obtained ceramic slurry is formed into sheets on a carrier sheet by a doctor blade process and the sheets are dried, whereby the ceramic green sheets for forming the insulating layers  19   a  to  19   g  are prepared. 
     Ceramic green sheets for forming the insulating layers  15   a  to  15   e  are prepared as shown in  FIG. 2 . In particular, raw materials are prepared by weighing ferric oxide (Fe 2 O 3 ), zinc oxide (ZnO), nickel oxide (NiO), and copper oxide (CuO) at a predetermined ratio and are charged into a ball mill, followed by wet mixing. An obtained mixture is dried and is then pulverized. An obtained powder is calcined at 800° C. for one hour. The calcined powder is wet-pulverized in a ball mill, is dried, and is then disintegrated, whereby a ferrite ceramic powder is obtained. 
     This ferrite ceramic powder is mixed with a binder (vinyl acetate, a water-soluble acrylic resin, or the like), a plasticizer, a humectant, and a dispersant in a ball mill, followed by defoaming under reduced pressure. An obtained ceramic slurry is formed into sheets on a carrier sheet by a doctor blade process and the sheets are dried, whereby the ceramic green sheets for forming the insulating layers  15   a  to  15   e  are prepared. 
     Ceramic green sheets for forming the insulating layers  16   a  to  16   g  are prepared as shown in  FIG. 2 . In particular, raw materials are prepared by weighing ferric oxide (Fe 2 O 3 ), zinc oxide (ZnO), nickel oxide (NiO), and copper oxide (CuO) at a predetermined ratio and are charged into a ball mill, followed by wet mixing. An obtained mixture is dried and is then pulverized. An obtained powder is calcined at 800° C. for one hour. The calcined powder is wet-pulverized in a ball mill, is dried, and is then disintegrated, whereby a ferrite ceramic powder is obtained. 
     This ferrite ceramic powder is mixed with a binder (vinyl acetate, a water-soluble acrylic resin, or the like), a plasticizer, a humectant, and a dispersant in a ball mill, followed by defoaming under reduced pressure, whereby a ceramic slurry for ceramic layers for forming the insulating layers  16   a  to  16   g  is obtained. 
     As shown in  FIG. 2 , the via-hole conductors b 1  to b 6  are each formed on a corresponding one of the ceramic green sheets for forming the insulating layers  19   a  to  19   f . In particular, a laser beam is applied to the ceramic green sheets for forming the insulating layers  19   a  to  19   f , whereby via-holes are formed therein. The via-holes are filled with a conductive paste containing Ag, Pd, Cu, Au, an alloy thereof, or the like by a process such as printing or painting. 
     As shown in  FIG. 2 , the coil conductors  18   a  to  18   g  are formed on the ceramic green sheets for forming the insulating layers  19   a  to  19   g . In particular, a conductive paste made of Ag, Pd, Cu, Au, an alloy thereof, or the like is applied to the ceramic green sheets for forming the insulating layers  19   a  to  19   g  by a process such as screen printing or photolithography, whereby the coil conductors  18   a  to  18   g  are formed. The formation of the coil conductors  18   a  to  18   g  and the filling of the via-holes with the conductive paste can be performed in the same step or in different steps. 
     As shown in  FIG. 2 , ceramic green layers for forming the insulating layers  16   a  to  16   g  are formed on portions of the ceramic green sheets for forming the insulating layers  19   a  to  19   g , the portions being other than the coil conductors  18   a  to  18   g . In particular, a ceramic paste is applied thereto by a process such as screen printing or photolithography, whereby the ceramic green layers for forming insulating layers  16   a  to  16   g  are formed. Through the above steps, ceramic green layers for forming the unit layers  17   a  to  17   g  are formed as shown in  FIG. 2 . 
     As shown in  FIG. 2 , the ceramic green sheets for forming the insulating layers  15   a  to  15   c , the ceramic green layers for forming the unit layers  17   a  to  17   g , and the ceramic green sheets for forming the insulating layers  15   d  and  15   e  are stacked in that order and are then press-bonded, whereby an uncalcined mother laminate is obtained. In particular, the ceramic green sheets for forming the insulating layers  15   a  to  15   c , the ceramic green layers for forming the unit layers  17   a  to  17   g , and the ceramic green sheets for forming the insulating layers  15   d  and  15   e  are stacked one by one and are preliminarily press-bonded and the uncalcined mother laminate is then pressed by isostatic pressing, whereby final press bonding is performed. 
     The coil L is formed during stacking because the ceramic green layers for forming the unit layers  17   a  to  17   g  are continuously arranged in the z-axis direction. This allows the coil conductors  18   a  to  18   g  and the insulating layers  19   a  to  19   g  to be alternately arranged in the uncalcined mother laminate in the z-axis direction as shown in  FIG. 2 . 
     The mother laminate is cut into laminates  12   a  with a predetermined size (2.5 mm×2.0 mm×1.0 mm) with a cutting blade, whereby the uncalcined laminates  12   a  are obtained. The uncalcined laminates  12   a  are degreased and are calcined. Degreasing is performed at, for example, 500° C. for two hours in a low-oxygen atmosphere. Calcination is performed at, for example, 870-900° C. for 2.5 hours. 
     During calcination, Ni diffuses from the insulating layers  15   c ,  16   a  to  16   g , and  15   d  to the insulating layers  19   a  to  19   g . In particular, the second portions  22   a  to  22   g  of the insulating layers  19   a  to  19   g  are in contact with the insulating layers  15   c ,  16   a  to  16   g , and  15   d  as shown in  FIG. 3  and therefore Ni diffuses from the insulating layers  15   c ,  16   a  to  16   g , and  15   d  to the second portions  22   a  to  22   g . Therefore, the second portions  22   a  to  22   g  become magnetized. The Ni content of the second portions  22   a  to  22   g  is lower than the second Ni content of the insulating layers  15   c ,  16   a  to  16   g , and  15   d.    
     In contrast, the first portions  20   a  to  20   f  of the insulating layers  19   a  to  19   f  are not in contact with the insulating layers  15   c ,  16   a  to  16   g , and  15   d  and therefore no Ni diffuses from the insulating layers  15   c ,  16   a  to  16   g , and  15   d  to the first portions  20   a  to  20   f . Thus, the first portions  20   a  to  20   f  remain non-magnetic. The first portions  20   a  to  20   f  originally contain no Ni and, however, can contain Ni, which diffuses from the second portions  22   a  to  22   g . Therefore, the first portions  20   a  to  20   f , while essentially free of Ni, may contain a slight or a trace amount of Ni so as not be magnetic. 
     Through the above steps, the calcined laminates  12   a  are obtained. The laminates  12   a  are chamfered by barreling. An electrode paste made of silver is applied to the laminates  12   a  by, for example, a dipping process or the like and the laminates  12   a  are then baked, whereby silver electrodes for forming external electrodes  14   a  and  14   b  are formed. The silver electrodes are baked at 800° C. for one hour. 
     Finally, the silver electrodes are plated with Ni and Sn, whereby the external electrodes  14   a  and  14   b  are formed. Through the above steps, the electronic component  10   a  shown in  FIG. 1  is completed. 
     In the electronic component  10   a  and the method, the occurrence of magnetic saturation due to a magnetic flux surrounding each of the coil conductors  18   a  to  18   f  can be prevented as described below. In particular, as shown in  FIG. 3 , when a current flows through the coil L of the electronic component  10   a , a magnetic flux φ 1  which has a relatively long flux path and which entirely surrounds the coil conductors  18   a  to  18   f  is generated and magnetic fluxes φ 2  which have a relatively short flux path and which each surround a corresponding one of the coil conductors  18   a  to  18   f  are generated (only a magnetic flux φ 2  surrounding the coil conductor  18   d  is shown in  FIG. 3 ). The magnetic fluxes φ 2 , as well as the magnetic flux φ 1 , can cause magnetic saturation in the electronic component  10   a.    
     In each electronic component  10   a  manufactured by the method, the first portions  20   a  to  20   f  of the insulating layers  19   a  to  19   f  are sandwiched between the coil conductors  18   a  to  18   g  in the z-axis direction and are non-magnetic. Therefore, the magnetic fluxes φ 2 , which each surround a corresponding one of the coil conductors  18   a  to  18   f , pass through the first portions  20   a  to  20   f , which are non-magnetic. Thus, the magnetic fluxes φ 2  have excessively high flux density; hence, magnetic saturation is prevented from occurring in the electronic component  10   a . This allows the electronic component  10   a  to have enhanced direct current superposition characteristics. 
     The inventor has performed computer simulations as described below for the purpose of clarifying effects resulting from the electronic component  10   a  and the method. In particular, a first model corresponding to the electronic component  10   a  and a second model including magnetic layers corresponding to the insulating layers  19   a  to  19   g  of the electronic component  10   a  have been manufactured. Simulation conditions are as described below:
         The number of turns in the coil L: 8.5 turns   The size of the electronic component: 2.5 mm×2.0 mm×1.0 mm   The thickness of the insulating layers  19   a  to  19   g : 10 μm       

       FIG. 4  is a graph showing the simulation results. The ordinate represents the inductance and the abscissa represents the current. As is clear from  FIG. 4 , the inductance of the first model decreases more gently with an increase in current as compared to the second model. That is, the first model has direct current superposition characteristics more excellent than those of the second model. This means that magnetic saturation is more likely to occur due to a magnetic flux surrounding each coil electrode in the second model than the first model. As is clear from the above, in the electronic component  10   a  and the method, magnetic saturation can be prevented from occurring due to the magnetic fluxes φ 2 , which each surround a corresponding one of the coil conductors  18   a  to  18   f.    
     In the electronic component  10   a  and the method, non-magnetic layers are the first portions  20   a  to  20   f , which are sandwiched between the coil conductors  18   a  to  18   f . Thus, the magnetic flux φ 1 , which surrounds the coil conductors  18   a  to  18   f , does not pass through any non-magnetic layer. Therefore, the electronic component  10   a  can achieve high inductance. 
     In the electronic component  10   a  and the method, the first portions  20   a  to  20   f , which are non-magnetic, can be accurately formed. In a common electronic component, in order to form a non-magnetic layer on a portion sandwiched between coil conductors, a process of applying a non-magnetic paste to the portion sandwiched between the coil conductors by printing may be used. 
     However, in the case of using the process of applying the non-magnetic paste thereto, the non-magnetic layer may possibly extend outside the portion sandwiched between the coil conductors because of misprinting or misalignment. When the non-magnetic layer extends outside the portion sandwiched between the coil conductors, the non-magnetic layer may possibly disturb a magnetic flux which entirely surrounds the coil conductors and which has a long flux path. That is, a magnetic flux other than a desired magnetic flux passes through the non-magnetic layer. 
     In the electronic component  10   a  and the method, after the laminate  12   a  is prepared, the first portions  20   a  to  20   f , which are non-magnetic, are formed during calcination. Therefore, misprinting or misalignment does not cause the first portions  20   a  to  20   f  to extend outside portions sandwiched between the coil conductors  18   a  to  18   f . In the electronic component  10   a  and the method, the first portions  20   a  to  20   f , which are non-magnetic, can be accurately formed. Therefore, unlike the desired magnetic fluxes φ 2 , the magnetic flux φ 1  is prevented from passing through any non-magnetic layer. 
     In the electronic component  10   a , the unit layers  17   a  to  17   g  are continuously arranged between a group of the insulating layers  15   a  to  15   c  and a group of the insulating layers  15   d  and  15   e  in that order. This allows non-magnetic layers to be present only in the first portions  20   a  to  20   f , which are sandwiched between the coil conductors  18   a  to  18   g . Therefore, no non-magnetic layer crossing the coil L is present. 
     In the electronic component  10   a  and the method, the insulating layers  19   a  to  19   g  preferably have a thickness of 5 μm to 15 μm. When the thickness of the insulating layers  19   a  to  19   g  is less than 5 μm, it is difficult to prepare the ceramic green sheets for forming the insulating layers  19   a  to  19   g . In contrast, when the thickness of the insulating layers  19   a  to  19   g  is more than 15 μm, Ni does not diffuse sufficiently and therefore it is difficult to magnetize the second portions  22   a  to  22   g.    
     No non-magnetic layer crossing the coil L is present in the electronic component  10   a . However, in the electronic component  10   a , non-magnetic layers may be present on portions other than the first portions  20   a  to  20   f . This is because direct current superposition characteristics of the electronic component and the inductance thereof can be adjusted using such non-magnetic layers. Electronic components, according to modifications, including non-magnetic layers placed on portions other than the first portions  20   a  to  20   f  are now described. 
     An electronic component  10   b  according to a first exemplary modification and an exemplary method of manufacturing the electronic component  10   b  are now described with reference to  FIG. 5 , which is a structural sectional view of the electronic component  10   b  according to the first exemplary modification. In order to avoid the complexity of  FIG. 5 , some of reference numerals representing the same members as those shown in  FIG. 3 , which can be present in the first exemplary modification, are not shown in  FIG. 5 . 
     A difference between the electronic component  10   a  and the electronic component  10   b  is that the electronic component  10   b  includes an insulating layer  24   d  which is non-magnetic instead of the insulating layer  16   d , which is magnetic. This allows the insulating layer  24   d , which is non-magnetic, to cross a coil L. Therefore, magnetic saturation due to a magnetic flux φ 1  is prevented from occurring in the electronic component  10   b.    
     In the exemplary method of manufacturing the electronic component  10   b , a via-hole conductor b 4  is formed in a ceramic green sheet for forming an insulating layer  19   d . A procedure for forming the via-hole conductor b 4  is as described above and therefore will not be repeated here. 
     A coil conductor  18   d  is formed on the ceramic green sheet for forming the insulating layer  19   d . A procedure for forming the coil conductor  18   d  is as described above and therefore will not be repeated here. 
     A ceramic green layer for forming the insulating layer  24   d  is formed on a portion of the ceramic green sheet for forming the insulating layer  19   d , the portion being other than the coil conductor  18   d . In particular, the ceramic green layer for forming the insulating layer  24   d  is formed in such a manner that a non-magnetic paste is applied to the portion by a process such as screen printing or photolithography. Through the above steps, a ceramic green layer for forming a unit layer  26   d  is formed. 
     Ceramic green sheets for forming insulating layers  15   a  to  15   c ; ceramic green layers for forming unit layers  17   a  to  17   c ,  26   d , and  17   e  to  17   g ; and ceramic green sheets for forming insulating layers  15   d  and  15   e  are stacked in that order and are then press-bonded, whereby an uncalcined mother laminate is obtained. Other steps of the method of manufacturing the electronic component  10   b  are the same as those of the method of manufacturing the electronic component  10   a  and therefore will not be repeated here. 
     An electronic component  10   c  according to a second exemplary modification and an exemplary method of manufacturing the electronic component  10   c  are now described with reference to  FIG. 6 , which is a structural sectional view of the electronic component  10   c  according to the second modification. In order to avoid the complexity of  FIG. 6 , some of reference numerals representing the same members as those shown in  FIG. 3 , which can be present in the second exemplary modification, are not shown in  FIG. 6 . 
     A difference between the electronic component  10   a  and the electronic component  10   c  is that the electronic component  10   c  includes insulating layers  28   b  and  28   f  which are non-magnetic and insulating layers  30   b  and  30   f  which are magnetic instead of the insulating layers  16   b  and  16   f , which are magnetic. That is, in the electronic component  10   c , the insulating layers  28   b  and  28   f , which are non-magnetic, are arranged outside a coil L. This allows a magnetic flux φ 1  to pass through the insulating layers  30   b  and  30   f , which are magnetic, thereby preventing magnetic saturation due to the magnetic flux φ 1  from occurring in the electronic component  10   c.    
     In the exemplary method of manufacturing the electronic component  10   c , via-hole conductor b 2  and b 6  are formed in ceramic green sheets for forming insulating layers  19   b  and  19   f . A procedure for forming the via-hole conductors b 2  and b 6  is as described above and therefore will not be repeated here. 
     Coil conductors  18   b  and  18   f  are formed on the ceramic green sheets for forming the insulating layers  19   b  and  19   f . A procedure for forming the coil conductors  18   b  and  18   f  is as described above and therefore will not be described. 
     Ceramic green layers for forming the insulating layers  28   b  and  30   b  are formed on portions of the ceramic green sheet for forming the insulating layer  19   b , the portions being other than the coil conductor  18   b . Ceramic green layers for forming the insulating layers  28   f  and  30   f  are formed on portions of the ceramic green sheet for forming the insulating layer  19   f , the portions being other than the coil conductor  18   f . In particular, the insulating layers  28   b  and  28   f  are formed on portions of the ceramic green sheets for forming the insulating layers  19   b  and  19   f , the portions being outside the coil conductors  18   b  and  18   f . The insulating layers  30   b  and  30   f  are formed on portions of the ceramic green sheets for forming the insulating layers  19   b  and  19   f , the portions being inside the coil conductors  18   b  and  18   f . The ceramic green layers for forming the insulating layers  28   b  and  28   f  are made from a non-magnetic ceramic paste (that is, a ceramic paste containing no Ni). The ceramic green layers for forming the insulating layers  30   b  and  30   f  are made from a magnetic ceramic paste (that is, a ceramic paste containing Ni). The magnetic and non-magnetic ceramic pastes are applied to the portions by a process such as screen printing or photolithography, whereby the ceramic green layers for forming the insulating layers  28   b ,  28   f ,  30   b , and  30   f  are formed. Through the above steps, ceramic green layers for forming unit layers  32   b  and  32   f  are formed. 
     Ceramic green sheets for forming insulating layers  15   a  to  15   c ; ceramic green layers for forming unit layers  17   a ,  32   b ,  17   c  to  17   e ,  32   f , and  17   g ; and ceramic green sheets for forming insulating layers  15   d  and  15   e  are stacked in that order and are then press-bonded, whereby an uncalcined mother laminate is obtained. Other steps of the method of manufacturing the electronic component  10   c  are the same as those of the method of manufacturing the electronic component  10   a  and therefore will not be repeated here. 
     An electronic component  10   d  according to a third exemplary modification and an exemplary method of manufacturing the electronic component  10   c  are now described with reference to  FIG. 7 , which is a structural sectional view of the electronic component  10   d  according to the third exemplary modification. In order to avoid the complexity of  FIG. 7 , some of reference numerals representing the same members as those shown in  FIG. 3 , which can be present in the third exemplary modification, are not shown  FIG. 7 . 
     A first difference between the electronic component  10   a  and the electronic component  10   d  is that the electronic component  10   d  includes an insulating layer  36   b  that is non-magnetic and an insulating layer  34   b  that is magnetic instead of the insulating layer  16   b , which is magnetic. A second difference between the electronic component  10   a  and the electronic component  10   d  is that the electronic component  10   d  includes an insulating layer  28   f  which is non-magnetic and an insulating layer  30   f  which is magnetic instead of the insulating layer  16   f , which is magnetic. 
     In the electronic component  10   d , the insulating layer  36   b , which is non-magnetic, is placed inside a coil L and the insulating layer  28   f , which is non-magnetic, is placed outside the coil L. This allows a magnetic flux φ 1  to pass through the insulating layers  36   b  and  28   f , which are non-magnetic, thereby preventing magnetic saturation due to the magnetic flux φ 1  from occurring in the electronic component  10   d.    
     In the exemplary method of manufacturing the electronic component  10   d , via-hole conductors b 2  and b 6  are formed in ceramic green sheets for forming insulating layers  19   b  and  19   f . A procedure for forming the via-hole conductors b 2  and b 6  is as described above and therefore will not be repeated here. 
     Coil conductors  18   b  and  18   f  are formed on the ceramic green sheets for forming the insulating layers  19   b  and  19   f . A procedure for forming the coil conductors  18   b  and  18   f  is as described above and therefore will not be repeated here. 
     Ceramic green layers for forming the insulating layers  34   b  and  36   b  are formed on portions of the ceramic green sheet for forming the insulating layer  19   b , the portions being other than the coil conductor  18   b . Ceramic green layers for forming the insulating layers  28   f  and  30   f  are formed on portions of the ceramic green sheet for forming the insulating layer  19   f , the portions being other than the coil conductor  18   f . In particular, the insulating layer  34   b  is formed on a portion of the ceramic green sheet for forming the insulating layer  19   b , the portion being outside the coil conductor  18   b . The insulating layer  36   b  is formed on a portion of the ceramic green sheet for forming the insulating layer  19   b , the portion being inside the coil conductor  18   b . The insulating layer  28   f  is formed on a portion of the ceramic green sheet for forming the insulating layer  19   f , the portion being outside the coil conductor  18   f . The insulating layer  30   f  is formed on a portion of the ceramic green sheet for forming the insulating layer  19   f , the portion being inside the coil conductor  18   f . The ceramic green layers for forming the insulating layers  28   f  and  36   b  are made from a non-magnetic ceramic paste (that is, a ceramic paste containing no Ni). The ceramic green layers for forming the insulating layers  30   f  and  34   b  are made from a magnetic ceramic paste (that is, a ceramic paste containing Ni). The magnetic and non-magnetic ceramic pastes are applied to the portions by a process such as screen printing or photolithography, whereby the ceramic green layers for forming the insulating layers  28   f ,  30   f ,  34   b , and  36   b  are formed. Through the above steps, ceramic green layers for forming unit layers  38   b  and  32   f  are formed. 
     Ceramic green sheets for forming insulating layers  15   a  to  15   c ; ceramic green layers for forming unit layers  17   a ,  38   b ,  17   c  to  17   e ,  32   f , and  17   g ; and ceramic green sheets for forming insulating layers  15   d  and  15   e  are stacked in that order and are then press-bonded, whereby an uncalcined mother laminate is obtained. Other steps of the method of manufacturing the electronic component  10   d  are the same as those of the method of manufacturing the electronic component  10   a  and therefore will not be described. 
     The electronic components  10   a  to  10   d  are prepared by a sequential press-bonding process and may be prepared by a printing process. 
     Embodiments consistent with the present disclosure are useful for providing an electronic component and a method of manufacturing the same. Such embodiments are excellent in being capable of preventing the occurrence of magnetic saturation due to a magnetic flux surrounding each coil conductor.