Abstract:
The invention relates to a method of manufacturing a coil component uses as a major part of a common mode choke coil or a transformer, and there is provided a method of manufacturing a compact and low height coil component in which deterioration of impedance characteristics is low and reliability is high. An insulating film is formed on a magnetic substrate, and open regions are formed in the insulating film. A lead terminal portion is formed on the insulating film, and a planarizing film is formed on the open regions. An insulating film is formed and openings are formed in the insulating film at the open regions. A coil conductor is formed on the insulating film, and a planarizing film is further formed on the planarizing film. After a coil conductor is further formed on the coil conductor through the insulating film, the planarizing films are removed.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a coil component uses as a major component or the like of a common mode choke coil or transformer and a method of manufacturing the same. 
   2. Description of the Related Art 
   Reductions in the size of electronic equipments such as personal computers and portable phones have resulted in demand for reductions in the size and thickness (low height) of electronic components such as coils and capacitors that are mounted on circuits in electronic equipments. 
   However, a wound-wire coil provided by winding a copper wire or the like around a ferrite core has a problem in that it is difficult to make compact because of structural limitations. Under the circumstance, research and development is active on chip type coil components, which can be provided with a small size and a low height. Known chip type coil components include multi-layer type coil components provided by forming a coil conduct or pattern on a surface of a magnetic sheet such as ferrite and stacking such magnetic sheets and thin film type coil components provided by alternately forming insulating films and coil conductors in the form of metal thin films using thin film formation techniques. 
   As a thin film type coil component, a common mode choke coil is known. The common mode choke coil has such a structure that two coil conductors in the form of spirals provided opposite to each other through an insulating film are embedded in an insulating layer formed between two ferrite substrates (magnetic substrates) disposed to be opposite to each other. Open regions are formed at an inner peripheral side and an outer peripheral side of the spiral coil conductor. A magnetic layer made of a magnetic material obtained by mixing magnetic powder in an insulating material is formed in the open region. When power is applied to the coil conductors, a closed magnetic path is formed on a section including the center axis of the coil conductor. 
   A conventional method of manufacturing a common mode choke coil will be described with reference to  FIGS. 8A to 10B .  FIGS. 8A to 10B  are manufacturing process sectional views of a common mode choke coil. First, as shown in  FIG. 8A , an insulating film  59   a  is formed on a magnetic substrate  53 , and open regions  65  and  67  are opened by patterning the insulating film  59   a . Next, as shown in  FIG. 8B , a lead terminal portion  71  is formed in the vicinity of, for example, the open region  65  on the insulating film  59   a . Next, as shown in  FIG. 8C , an insulating film  59   b  is formed on the entire surface, and a contact hole  75  in which the lead terminal portion  71  is exposed and openings at the open regions  65  and  67  are formed by patterning the insulating film  59   b.    
   Next, as shown in  FIG. 8D , a coil conductor  61  patterned into a spiral shape is formed on the insulating film  59   b  by using a frame plating method. One end of the coil conductor  61  is formed on the lead terminal portion  71  exposed in the contact hole  75 . As a result, the coil conductor  61  and the lead terminal portion  71  are electrically connected to each other. 
   Next, as shown in  FIG. 9A , an insulating film  59   c  is formed on the entire surface, and openings at the open regions  65  and  67  are formed by pattering the insulating film  59   c . Next, as shown in  FIG. 9B , a coil conductor  63  patterned into a spiral shape is formed on the insulating film  59   c  by using the frame plating method. 
   Next, as shown in  FIG. 9C , an insulating film  59   d  is formed on the entire surface, and a contact hole  77  in which one end of the coil conductor  63  is exposed and openings at the open regions  65  and  67  are formed by patterning the insulating film  59   d.    
   Next, a lead terminal portion  73  is formed on the insulating film  59   d . As shown in  FIG. 9D , one end of the lead terminal portion  73  is formed on the one end of the coil conductor  63  exposed in the contact hole  77 . As a result, the coil conductor  63  and the lead terminal portion  73  are electrically connected to each other. 
   Next, as shown in  FIG. 10A , an insulating film  59   e  is formed on the entire surface, and the open regions  65  and  67  are opened by patterning insulating film  59   e . Next, as shown in  FIG. 10B , composite ferrite obtained by mixing magnetic powder of ferrite in insulating resin is embedded in the open regions  65  and  67  to form magnetic layers  68 . Next, an adhesive is applied on the magnetic layers  68  in the open regions  65  and  67  and the insulating film  59   e  to form an adhesive layer  69 . Next, a magnetic substrate  55  is attached to the adhesive layer  69 , and the common mode choke coil is completed. 
   In order to improve impedance characteristics by increasing magnetic coupling between the coil conductors  61  and  63  and by increasing common impedance, the film thickness of the insulating film  59   c  between the coil conductors  61  and  63  is required to be made uniform and flat. Further, the film thicknesses of the coil conductors  61  and  63  are made uniform, and the sectional shapes of the coil conductors  61  and  63  orthogonal to the direction of the flow of current are required to be made almost identical independently of place. 
   However, each of the insulating films  59   a  to  59   e  is formed by applying, for example, polyimide resin on the entire surface and is patterned to provide the openings at the open regions  65  and  67 . The polyimide resin applied in the open regions  65  and  67  is removed each time the respective insulating films  59   a  to  59   e  are formed, and the magnetic substrate  53  is always exposed in the open regions  65  and  67 . Thus, a large step occurs between the upper surface of the insulating film and the surface of the magnetic substrate  53  exposed in the open regions  65  and  67 . By the influence of the step, as shown in  FIG. 9B , the film thickness of the insulating film  59   c  is decreased in the vicinity of the open regions  65  and  67 , and the film thickness of the insulating film  59   c  in the vicinity of the open regions  65  and  67  is different from that in the other area, and as a result, there arises a problem that the interval between the coil conductors  61  and  63  becomes uneven. 
   Further, since the coil conductor  63  is formed on the insulating film  59   c  having the uneven film thickness, as shown in  FIG. 9B , the sectional shape of the coil conductor  63  also becomes uneven between the vicinity of the open regions  65  and  67  and the other area. Also in the patterning of the resist frame for the formation of the coil conductor  63 , the height of the resist frame becomes uneven between the vicinity of the open regions  65  and  67  and the other area, and there is a possibility that the plating film overflows onto the upper surface of the resist frame formed to have the low height, and the sectional shape of the coil conductor  63  becomes uneven. Further, there is also a problem that the resistance value of the coil conductor  63  locally varies due to the unevenness of the sectional shape of the coil conductor  63 . 
   As stated above, when the film thickness of the insulating film  59   c  becomes uneven, the magnetic coupling between the coil conductors  61  and  63  becomes small, the common impedance is lowered, and the impedance characteristic is deteriorated. Further, the manufacture of the common mode choke coil having high impedance becomes difficult by the unevenness of the film thickness of the insulating film  59   c  and the unevenness of the sectional shape of the coil conductor  63 . 
   SUMMARY OF THE INVENTION 
   An object of the invention is to provide a method of manufacturing a coil component which can manufacture a compact and low height coil component superior in impedance characteristics. 
   The above object is achieved by a method of manufacturing a coil component characterized in that it has the steps of forming an insulating film on a magnetic substrate, forming a predetermined open region in the insulating film, forming a planarizing film in the open region, forming a coil conductor made of a conductive material on the insulating film, forming an insulating film on the coil conductor, and removing the planarizing film. 
   A method of manufacturing a coil component according to the invention is characterized in that the planarizing film is formed by using the conductive material and at the same time as formation of the coil conductor. 
   A method of manufacturing a coil component according to the invention is characterized in that the planarizing film is formed before formation of the coil conductor. 
   A method of manufacturing a coil component according to the invention is characterized in that a planarizing film is further formed on the planarizing film by using the conductive material and at the same time as formation of the coil conductor. 
   Besides, the above object is achieved by a method of manufacturing a coil component characterized in that it has the steps of forming a first insulating film on a first magnetic substrate, forming a predetermined open region in the first insulating film, forming a first metal layer on a entire surface, forming a first lead terminal portion on the first insulating film and a first planarizing film on the open region by patterning the first metal layer, forming a second insulating film on a entire surface, forming an opening in the second insulating film at the open region, forming a second metal layer on a entire surface, forming a first coil conductor in a spiral shape on the second insulating film so that the open region is positioned at an inner peripheral side and a second planarizing film on the first planarizing film by patterning the second metal layer, forming a third insulating film on a entire surface, forming an opening in the third insulating film at the open region, forming a third metal layer on a entire surface, forming a second coil conductor in a spiral shape on the third insulating film so that the open region is positioned at an inner peripheral side by patterning the third metal layer, forming a fourth insulating film on a entire surface, forming an opening in the fourth insulating film at the open region, forming a fourth metal layer on a entire surface, forming a second lead terminal portion on the fourth insulating film by patterning the fourth metal layer, forming a fifth insulating film on a entire surface, forming an opening in the fifth insulating film at the open region, removing the first and the second planarizing films, forming a magnetic layer embedded in at least the open region, and attaching a second magnetic substrate onto the magnetic layer. 
   A method of manufacturing a coil component according to the invention is characterized in that a same metal material is used for the first to the fourth metal layers. 
   A method of manufacturing a coil component according to the invention is characterized in that the metal material is copper. 
   A method of manufacturing a coil component according to the invention is characterized in that the coil conductor is formed using a frame plating method. 
   According to the invention, a compact and low height coil component excellent in impedance characteristics can be manufactured. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a view showing a section of a common mode choke coil  1  of an embodiment of the invention taken along the imaginary line A-A of  FIGS. 2A and 2B ; 
       FIGS. 2A and 2B  are views showing coil conductors  11  and  13  of the common mode choke coil  1  of the embodiment of the invention, in which  FIG. 2A  shows a plane shape including the coil conductor  11 , and  FIG. 2B  shows a plane shape including the coil conductor  13 ; 
       FIGS. 3A to 3D  are sectional views showing a manufacturing process of the common mode choke coil  1  of the embodiment of the invention; 
       FIGS. 4A to 4C  are sectional views showing a manufacturing process of the coil conductor  11  and a planarizing film  31  of the common mode choke coil  1  of the embodiment of the invention; 
       FIGS. 5A to 5C  are sectional views showing the manufacturing process of the coil conductor  11  and the planarizing film  31  of the common mode choke coil  1  of the embodiment of the invention; 
       FIGS. 6A to 6D  are sectional views showing the manufacturing process of the common mode choke coil  1  of the embodiment of the invention; 
       FIGS. 7A and 7B  are sectional views showing the manufacturing process of the common mode choke coil  1  of the embodiment of the invention; 
       FIGS. 8A to 8D  are sectional views showing a conventional manufacturing process of a common mode choke coil; 
       FIGS. 9A to 9D  are sectional views showing the conventional manufacturing process of the common mode choke coil; and 
       FIGS. 10A and 10B  are sectional views showing the conventional manufacturing process of the common mode choke coil. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A coil component and a method of manufacturing the same according to an embodiment of the invention will be described with reference to  FIGS. 1 to 7B . In this embodiment, a description will be made while a common mode choke coil for suppressing common mode current causing electromagnetic interference in a balanced transmission system is used as an example of the coil component. First, a structure of a common mode choke coil  1  will be described with reference to  FIGS. 1 to 2B .  FIG. 1  shows a section of the common mode choke coil  1  taken along an imaginary line A-A of  FIGS. 2A and 2B .  FIG. 2A  shows a plane shape of the common mode choke coil  1  including a coil conductor  11 .  FIG. 2B  shows a plane shape including a coil conductor  13 . 
   As shown in  FIG. 1 , the common mode choke coil  1  of this embodiment has such a structure that an insulating film  9   a , a lead terminal portion  21 , an insulating film  9   b , a coil conductor  11  made of conductive material, an insulating film  9   c , a coil conductor  13  made of conductive material, an insulating film  9   d , a lead terminal portion  23  and an insulating film  9   e  are laminated in this order on a magnetic substrate  3  formed of ferrite. The coil conductor  11  and the coil conductor  13  face each other through the insulating film  9   c . The coil conductors  11  and  13  are embedded in an insulating layer  9  constituted by the insulating films  9   a  to  9   e . Each of the insulating films  9   a ,  9   b ,  9   c ,  9   d  and  9   e  of the insulating layer  9  is made of polyimide resin, and is formed by an after-mentioned manufacturing method to have an almost uniform and flat film thickness. At the inner peripheral side of the coil conductors  11  and  13 , the insulating layer  9  is removed and an open region  15  is formed. At the outer peripheral side of the coil conductors  11  and  13 , the insulating layer  9  is removed and an open region  17  is formed. 
   Magnetic layers  18  embedded in the open regions  15  and  17  are formed. The magnetic layers  18  are formed of composite ferrite obtained by mixing magnetic powder of ferrite in polyimide resin. Further, an adhesive layer  19  is formed on the magnetic layers  18  and the insulating film  9   e , and a magnetic substrate  5  formed of ferrite is adhered. 
   As shown in  FIG. 2A , the coil conductor  11  is formed into a spiral shape on the insulating film  9   b . The coil conductor  11  is connected to one terminal of the lead terminal portion  21  formed in a lower layer of the insulating film  9   b  and indicated by a broken line in the drawing through a contact hole  25  formed in the insulating film  9   b . The other terminal of the lead terminal portion  21  is connected to an electrode terminal (not shown) formed at a side surface of the common mode choke coil  1 . 
   As shown in  FIG. 2B , the lead terminal,portion  23  is formed on the insulating film  9   d . The spiral coil conductor  13  having almost the same shape as the coil conductor  11  and indicated by a broken line in the drawing is formed in a lower layer of the insulating film  9   d . The coil conductor  13  is connected to one terminal of the lead terminal portion  23  through a contact hole  27  formed in the insulating film  9   d . The other terminal of the lead terminal portion  23  is connected to another electrode terminal (not shown) formed at the side surface of the common mode choke coil  1 . 
   Next, the operation of the common mode choke coil  1  according to this embodiment will be described. When power is applied to the coil conductors  11  and  13 , as shown in  FIG. 1 , a magnetic path M passing through the magnetic substrate  3 , the magnetic layer  18  of the open region  15 , the adhesive layer  19 , the magnetic substrate  5 , the adhesive layer  19  and the magnetic layer  18  of the open region  17  in this order (or in reverse order) is formed in a section including the center axis of the coil conductors  11  and  13 . Although the adhesive layer  13  is nonmagnetic, it is a thin film of several μm thickness. Thus, a leak of magnetic lines of force is hardly generated in this portion, and the magnetic path M can be regarded as being an almost closed magnetic path. Accordingly, the common mode choke coil  1  has an excellent degree of magnetic coupling and an impedance characteristic. 
   Next, a method of manufacturing the common mode choke coil  1  according to this embodiment will be described with reference to  FIGS. 3A to 7B .  FIGS. 3A ,  3 B,  3 C,  3 D,  6 A,  6 B,  6 C,  6 D,  7 A and  7 B show the section of the common mode choke coil  1  taken along an imaginary line A-A of  FIGS. 2A and 2B . Incidentally, structural elements having the same operation and function as the structural elements of the common mode choke coil  1  shown in  FIGS. 1 ,  2 A and  2 B are denoted by the same symbols and their description will be omitted. 
   First, as shown in  FIG. 3A , polyimide resin is applied on a magnetic substrate (first magnetic substrate)  3  made of ferrite to form an insulating film (first insulating film)  9   a  having a thickness of 7 to 8 μm, and open regions  15  and  17  are formed by patterning the insulating film  9   a . Next, as shown in  FIG. 3B , a first metal layer (not shown) of Cu (copper) or the like is formed on the entire surface. A lead terminal portion (first lead terminal portion)  21  (see FIG.  2 A)having a thickness of 5 μm, one terminal of which is positioned in the vicinity of the open region  15  and the other terminal of which is positioned at the periphery of the magnetic substrate  3  is formed by patterning the first metal layer. At the same time, a planarizing film (first planarizing film)  29  having a thickness of 5 μm is formed by patterning the first metal layer in the open regions  15  and  17 . Since a step between the insulating film  9   a  and the open regions  15  and  17  is decreased by the planarizing film  29 , the thickness of an insulating film  9   b  formed at a subsequent process can be made very uniform and flat. 
   Next, as shown in  FIG. 3C , polyimide resin is applied on the entire surface to form an insulating film (second insulating film)  9   b  having a thickness of 7 to 8 μm, and a contact hole  25  in which one terminal of the lead terminal portion  21  is exposed and openings in which the planarizing film  29  is exposed at the open regions  15  and  17  are formed by patterning the insulating film  9   b.    
   Next, as shown in  FIG. 3D , a second metal layer (not shown) of a Cu layer or the like is formed on the entire surface, and a coil conductor (first coil conductor)  11  having a spiral shape and a thickness of 5 μm on the insulating film  9   b , and a planarizing film (second planarizing film)  31  on the planarizing film  29  formed in the open regions  15  and  17  are formed by patterning the second metal layer. One terminal of the coil conductor  11  is formed on the one terminal of the lead terminal portion  21  exposed in the contact hole  25 . As a result, the coil conductor  11  and the lead terminal portion  21  are electrically connected to each other. On the other hand, the other terminal is formed at the periphery of the magnetic substrate  3  opposite to the other terminal of the lead terminal portion  21  through the insulating film  9   b  (see  FIG. 2A ). 
   The coil conductor  11  and the planarizing film  31  are formed by using a frame plating method. The frame plating method will be described with reference to  FIGS. 4A to 5C . The frame plating method is a method of forming a plating film using a mold (frame) formed by patterning a resist layer.  FIGS. 4A to 5C  show a manufacturing process of the coil conductor  11  and the planarizing film  31 , and show a portion between the center part of the left open region  17  of  FIG. 3D  and the center part of the open region  15 . The insulating film  9   a , the lead terminal portion  21  and the insulating film  9   b  are formed in this order on the magnetic substrate  3  through the manufacturing process of  FIGS. 3A to 3D . Further, the planarizing film  29  is formed on the open regions  15  and  17 . As shown in  FIG. 4A , an electrode film  33  is formed on the entire surface by using a sputtering method or an evaporation method. An adhesive layer in the form of, for example, a Cr (chromium) film or a Ti (titanium) film may be formed under the electrode film  33  in order to improve the adhesiveness to the insulating film  9   b  and the planarizing film  29 . Although the electrode film  33  may be formed of any material as long as the material has conductivity, if possible, it is desirable to use the same material as the metal material to be plated. 
   Next, as shown in  FIG. 4B , a resist layer  35  is formed by applying a resist on the entire surface, and as the need arises, a pre-baking process is performed on the resist layer  35 . Next, exposure light is irradiated through a mask  37  on which a pattern of the coil conductor  11  and the planarizing film  31  is drawn, and the resist layer  35  is exposed to the light. 
   Next, after a heat treatment is performed as the need arises, development is performed using an alkaline developing solution. As the alkaline developing solution, for example, a tetramethyl ammonium hydroxide (TMAH) in a predetermined concentration is used. Next, the developing step is then followed by a cleaning step. The developing solution in the resist layer  35  is cleaned with a cleaning liquid, the developing and dissolving reaction of the resist layer  35  is stopped, and as shown in  FIG. 4C , a resist frame  39  patterned into a predetermined shape is formed. As the cleaning liquid, for example, pure water is used. 
   When the cleaning is completed, the cleaning liquid is scattered away to dry the magnetic substrate 3 . If necessary, the magnetic substrate  3  is heated to dry up the cleaning liquid. Next, as shown in  FIG. 5A , the magnetic substrate  3  is dipped in a plating solution in a plating bath, a plating process is performed using the resist frame  39  as the mold, and a plating film  41  is formed in gaps in the resist frame  39 . Next, as shown in  FIG. 5B , after rinsing and drying is performed as the need arises, the resist frame  39  is peeled off from the insulating film  9   b  by using an organic solvent. Next, as shown in  FIG. 5C , the electrode film  33  is removed by dry etching (ion milling, reactive ion etching (RIE), etc.) or wet etching using the plating film  41  as a mask. In this way, the coil conductor  11  and the planarizing film  31  are formed. Since a step between the insulating film  9   b  and the open regions  15  and  17  is decreased by the planarizing films  29  and  31 , the film thickness of the insulating film  9   c  formed at a subsequent process can be made very uniform and flat. 
   When the coil conductor  11  and the planarizing film  31  are formed using a the frame plating method, next, as shown in  FIG. 6A , polyimide resin is applied on the entire surface to form an insulating film (third insulating film)  9   c , and openings in which the planarizing film  31  is exposed at the upper parts of the open regions  15  and  17  are formed by patterning the insulating film  9   c . Next, as shown in FIG.  6 B, after a third metal layer (not shown) of a Cu layer or the like is formed, a coil conductor (second coil conductor)  13  patterned into a spiral shape and having a thickness of 5 μm is formed on the insulating film  9   c  by using a frame plating method. One terminal of the coil conductor  13  is formed in the vicinity of the open region  15 , and the other terminal is formed at the periphery of the magnetic substrate  3  to be adjacent to the other terminal of the coil conductor  11  through the insulating film  9   c . Since the coil conductor  13  is formed using a frame plating method similar to the method of manufacturing the coil conductor  11  and the planarizing film  31  described with reference to  FIGS. 4A to 5C , the description will be omitted. 
   Next, as shown in  FIG. 6C , polyimide resin is applied on the entire surface to form an insulating film (fourth insulating film)  9   d  having a thickness of 7 to 8 μm, and a contact hole  27  in which the one terminal of the coil conductor  13  is exposed and openings in which the planarizing film  31  at the open regions  15  and  17  are exposed are formed by patterning the insulating film  9   d.    
   Next, as shown in  FIG. 6D , a fourth metal layer (not shown) of a Cu layer or the like is formed on the entire surface and a lead terminal portion (second lead terminal portion)  23  having a thickness of 5 μm is formed by pattering the fourth metal layer. One terminal of the lead terminal portion  23  is formed on the one terminal of the coil conductor  13  exposed in the contact hole  27 . As a result, the coil conductor  13  and the lead terminal portion  23  are electrically connected to each other. On the other hand, the other terminal faces the other terminal of the coil conductor  13  through the insulating film  9   d  and is formed at the periphery of the magnetic substrate  3  (see  FIG. 2B ). 
   Next, as shown in  FIG. 7A , polyimide resin is applied on the entire surface to form an insulating film (fifth insulating film)  9   e  having a thickness of 7 to 8 μm, and openings in which the open regions  15  and  17  are exposed are formed by patterning the insulating film  9   e . Next, the planarizing films  29  and  31  are removed by wet etching. 
   Next, as shown in  FIG. 7B , composite ferrite obtained by mixing magnetic powder of ferrite in polyimide resin is embedded in the open regions  15  and  17  to form magnetic layers  18 . Next, an adhesive is applied on the magnetic layers  18  in the open regions  15  and  17  and the insulating film  9   e  to form an adhesive layer  19 . Next, a magnetic substrate (second magnetic substrate)  5  is attached to the adhesive layer  19 . 
   Next, although not shown, an electrode film (not shown) of Ni (nickel) is formed using a sputtering method at formation positions of the other terminals of the lead terminal portions  21  and  23  disposed at the side surface of the common mode choke coil  1  and the other terminals of the coil conductors  11  and  13  to be virtually orthogonal to the substrate surface of the magnetic substrate  3  and to cross a portion between the magnetic substrates  3  and  5 . Next, a film of alloy conductive material of Sn (tin), Ni and Cu (copper) is formed on the surface of the electrode film by barrel plating, an electrode terminal (not shown) having a two-layer structure made of Ni/Sn is formed, and the manufacture of the common mode choke coil  1  is completed. 
   As described above, in the method of manufacturing the common mode choke coil  1  of this embodiment, since the planarizing films  29  and  31  are formed to be laminated in the open regions  15  and  17 , the step between the insulating film  9   b  at the formation surface of the coil conductor  11  and the open regions  15  and  17  can be decreased. As a result, variations in thickness of the insulating film  9   c  formed on the insulating film  9   b  and on the planarizing film  31  exposed in the open regions  15  and  17  are reduced, and the insulating film  9   c  is formed to have a vary uniform thickness. Besides, even if the thickness of the insulating layer  9   c  is made thin, a sufficiently flat film can be obtained. Since the insulating film  9   b  is uniform in thickness and the coil conductor  13  is formed on the sufficiently flat insulating film  9   c , the resist layer having small thickness variation and patterning variation can be used. Thus, the interval between the coil conductors  11  and  13  can be made almost constant, the coil conductors  11  and  13  can be made close to and opposite to each other through the insulating film  9   c , and the aspect ratio can be made large. Accordingly, it is possible to realize the common mode choke coil  1  in which the magnetic coupling between the coil conductors  11  and  13  is stabilized, the excellent degree of magnetic coupling is obtained, and the impedance characteristic is further improved. 
   When the coil conductor  13  is formed, the plating distribution of the plating film  41  formed in the resist frame  39  shown in  FIGS. 4A to 5C  is improved, the film thickness of the plating film  41  becomes almost uniform, and the sectional shape of the coil conductor  13  orthogonal to the direction of the flow of current becomes almost constant. Accordingly, the resistance value of the coil conductor  13  can be stabilized. Further, by the realization of film thickness equalization and film flattening of the insulating film  9   c , and the equalization of the sectional shape of the coil conductor  13 , the common mode choke coil  1  having the high impedance can be stably manufactured. Further, since the process of removing the planarizing films  29  and  31  has only to be added, the common mode choke coil  1  can be manufactured at low cost while the manufacturing process is hardly increased. 
   The invention is not limited to the embodiment described above and may be modified in various ways. 
   In the above embodiment, although the coil conductors  11  and  13  and the planarizing film  31  are formed by using the frame plating method, the invention is not limited to this. For example, instead of the frame plating method, sputtering, physical vapor deposition or the like may be naturally used to form the coil conductors  11  and  13  and the planarizing film  31 . 
   In the above embodiment, although the planarizing films  29  and  31  are laminated in the open regions  15  and  17 , the invention is not limited to this. For example, only one of the planarizing film  29  and the planarizing film  31  may be formed in the open regions  15  and  17 . Also in this case, since the step between the insulating layer  9   b  at the formation surface of the coil conductor  11  and the open regions  15  and  17  is moderated to some degree, the variations in the thickness of the insulating film  9   c  can be suppressed. Besides, when only one layer is formed, a time of a removal process of the planarizing film can be shortened. 
   Besides, when the coil conductor  13  is formed, a planarizing film may be naturally further laminated on the planarizing films  29  and  31  of the open regions  15  and  17 . In this case, since the film thickness of the insulating film  9   d  can be made uniform and the film can be made flat, an interlayer short between the coil conductor  13  and the lead terminal portion  23  can be certainly prevented. 
   Besides, in the above embodiment, although the description has been made while the common mode choke coil  1  is used as an example of the coil component, the invention is not limited to this. For example, the invention may be naturally used for manufacture of a common mode choke coil array in which plural common mode choke coils are formed in an array shape. In this case, each of the common mode choke coils has excellent degree of magnetic coupling and impedance characteristics, and characteristic variation between the plural common mode choke coils can be suppressed, so that the high performance common mode choke coil array can be manufactured.