Patent Publication Number: US-2013241684-A1

Title: Method for manufacturing common mode filter and common mode filter

Description:
CROSS REFERENCE(S) TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. Section 119 of Korean Patent Application Serial No. 10-2012-0026674, entitled “Method for Manufacturing Common Mode Filter and Common Mode Filter” filed on Mar. 15, 2012, which is hereby incorporated by reference in its entirety into this application. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a method for manufacturing common mode filter and a common mode filter. 
     2. Description of the Related Art 
     A common mode filter (CMF) is an electronic component widely used in various electronic devices in order to remove common mode noise. 
     Recently, in accordance with miniaturization, slimness, and multi-functionalization of electronic products, research into a CMF capable of improving noise removing performance and being miniaturized and thinned has been continuously conducted. 
     In addition, various researches and attempts have been conducted in order to improve characteristics such as an inductance, direct current (DC) resistance, and the like, of the CMF. An example of these researches and attempts includes a CMF capable of increasing a cutoff frequency and improving an impedance characteristic as disclosed in Patent document 1. 
     Meanwhile, a method for manufacturing a common mode filter using a photo-resist process that has been currently applied widely is schematically shown in  FIG. 1 . 
     Referring to  FIG. 1 , in a thin film type CMF according to the related art, a coil pattern may be formed in a scheme in which a metal seed layer  20  is formed on a magnetic substrate  10 , a photo-resist is coated and developed on the metal seed layer  20  to form a photo-resist pattern  30 , and a conductive material  40  such as copper, or the like, is then filled in a region exposed by the photo-resist pattern  30 . 
       FIG. 2  is a view schematically showing a cross-section of a common mode filter according to the related art. Referring to  FIG. 2 , a relationship between a width w and a height h of a first coil pattern  50   a , and a spaced distance d between adjacent coil patterns will be appreciated. 
     As shown in  FIGS. 1 and 2 , in the case of forming a photo-resist pattern in a general photo-resist process according to the related art, there is a limitation in decreasing a width of the pattern, or an interval between the adjacent patterns. In this case, in order to increase volume of the coil pattern while constantly maintaining the entire width of the common mode filter, the spaced distance d between adjacent coils should be decreased. However, since there is a limitation in decreasing the spaced distance d between the adjacent coils due to the limitation in the photo-resist process described above, there is a restriction in improving characteristics of the common mode filter without increasing the entire size of the common mode filter. 
     RELATED ART DOCUMENT 
     [Patent Document] 
     
         
         (Patent Document 1) Korean Patent Laid-Open Publication No. 10-2011-0082641 
       
    
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a method for manufacturing common mode filter and a common mode filter that are capable of improving characteristics such as an inductance, direct current resistance, and the like, by increasing volume of a coil pattern. 
     According to an exemplary embodiment of the present invention, there is provided a method for manufacturing a common mode filter, including: performing electroplating on first coil patterns made of a conductive material to form second coil patterns having a cross-sectional area increased as compared to the first coil patterns. 
     The method may further include performing wet etching on a product obtained by performing the electroplating on the first coil pattern. 
     According to another exemplary embodiment of the present invention, there is provided a method for manufacturing a common mode filter, including: applying power to a lead wire electrically connected to one end of each of a plurality of first coil patterns made of a conductive material and performing electroplating to form a plurality of second coil patterns having a cross-sectional area increased as compared to the plurality of first coil patterns. 
     The method may further include, after the forming of the plurality of second coil patterns, performing a dicing process so that the plurality of second coil patterns are separated from each other, respectively, wherein the dicing process is performed along a dicing line set so that the lead wire is separated from one end of each of the plurality of second coil patterns. 
     The method may further include, after the performing of the wet etching on the product obtained by performing the electroplating, performing a dicing process so that the plurality of second coil patterns are separated from each other, respectively, wherein the dicing process is performed along a dicing line set so that the lead wire is separated from one end of each of the plurality of second coil patterns. 
     According to still another exemplary embodiment of the present invention, there is provided a method for manufacturing a common mode filter, including: forming a seed metal layer on a surface of a substrate; forming a photo-resist pattern on the seed metal layer so that a surface of the seed metal layer is partially exposed; plating the exposed surface of the seed metal layer with a metal; removing the seed metal layer positioned beneath the photo-resist pattern and the photo-resist pattern to form first coil patterns, and performing electroplating on the first coil patterns to form second coil patterns having a cross-sectional area increased as compared to the first coil patterns. 
     The method may further include performing wet etching on the second coil pattern. 
     According to still another exemplary embodiment of the present invention, there is provided a method for manufacturing a common mode filter including: forming a seed metal layer on a surface of a substrate; forming a photo-resist pattern so as to expose a region in which a plurality of first coil patterns are formed and a region in which a lead wire electrically connected to one end of each of the plurality of first coil patterns is formed, on the seed metal layer; plating the exposed surface of the seed metal layer with; a metal; removing the seed metal layer positioned beneath the photo-resist pattern and the photo-resist pattern to form the plurality of first coil patterns and the lead wire; and applying power to the lead wire to perform electroplating on the plurality of first coil patterns, thereby forming a plurality of second coil patterns having a cross-sectional area increased as compared the plurality of first coil patterns. 
     The method may further include, after the forming of the plurality of second coil patterns, performing a dicing process so that the plurality of second coil patterns are separated from each other, respectively, wherein the dicing process is performed along a dicing line set so that the lead wire is separated from one end of each of the plurality of second coil patterns. 
     The method may further include, after the performing of the wet etching on the product obtained by performing the electroplating, performing a dicing process so that the plurality of second coil patterns are separated from each other, respectively, wherein the dicing process is performed along a dicing line set so that the lead wire is separated from one end of each of the plurality of second coil patterns. 
     According to still another exemplary embodiment of the present invention, there is provided a common mode filter including: coil patterns made of a conductive material and formed on a substrate made of a magnetic material, wherein the coil pattern has a cross-sectional shape in which surface thereof facing the substrate is flat and the other surface thereof is oval. 
     In the coil pattern, a ratio of a long side horizontal to the surface facing the substrate to a short side vertical to the long side may be 1.1 to 2:1. 
     In the coil pattern, a ratio of a maximum distance from the long side to the surface facing the substrate to a maximum distance from the long side to an upper surface of the coil pattern may be 6.5:3.5 to 5.5:4.5. 
     In the coil pattern, an interval between adjacent coils may be 0.15 to 0.45 times of a length of the long side of the coil pattern. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view schematically showing a method for manufacturing a common mode filter (CMF) according to the related art; wherein  FIG. 1A  shows a step of providing a substrate,  FIG. 1B  shows a step of forming a seed metal layer,  FIG. 1C  shows a step of forming a photo-resist pattern,  FIG. 1D  shows a step of forming coil patterns,  FIG. 1E  shows a step of removing the photo-resist pattern, and  FIG. 1F  shows a step of removing the seed metal layer; 
         FIG. 2  is a view schematically showing a cross-section of the CMF according to the related art; 
         FIG. 3  is a view schematically showing a method for manufacturing a CMF according to an exemplary embodiment of the present invention; wherein  FIG. 3A  shows a step of providing a substrate,  FIG. 3B  shows a step of forming a seed metal layer,  FIG. 3C  shows a step of forming a photo-resist pattern,  FIG. 3D  shows a step of plating the seed metal layer exposed by the photo-resist pattern with a metal,  FIG. 3E  shows a step of removing the photo-resist pattern,  FIG. 3F  shows a step of removing the seed metal layer to form first coil patterns, and  FIG. 3G  shows a step of performing electroplating on the first coil patterns to form second coil patterns; 
         FIG. 4  is a view schematically showing a method for manufacturing a CMF according to another exemplary embodiment of the present invention; wherein  FIG. 4A  shows a step of providing a substrate, FIG.  4 B shows a step of forming a seed metal layer,  FIG. 4C  shows a step of forming a photo-resist pattern,  FIG. 4D  shows a step of plating a metal on the seed metal layer exposed by the photo-resist pattern,  FIG. 4E  shows a step of removing the photo-resist pattern,  FIG. 4F  shows a step of removing the seed metal layer to form first coil patterns,  FIG. 4G  shows a step of performing electroplating on the first coil pattern, and  FIG. 4H  shows a step of performing wet etching on a product of the electroplating to form second coil patterns; 
         FIG. 5  is a view photographing a cross-section of the CMF according to another exemplary embodiment of the present invention; 
         FIG. 6  is a view schematically showing a cross-section of the CMF according to the exemplary embodiment of the present invention; 
         FIG. 7A  is a view schematically showing a state in which a plurality of second coil patterns are connected to a lead wire in the method for manufacturing a CMF according to the exemplary embodiment of the present invention; 
         FIG. 7B  is an enlarged view of the part V of  FIG. 7A ; and 
         FIG. 7C  is a view schematically showing a state in which a dicing process is performed along a dicing line DL of  FIG. 7B . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Various advantages and features of the present invention and methods accomplishing thereof will become apparent from the following description of embodiments with reference to the accompanying drawings. However, the present invention may be modified in many different forms and it should not be limited to the embodiments set forth herein. These embodiments may be provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals throughout the description denote like elements. 
     Terms used in the present specification are for explaining the embodiments rather than limiting the present invention. Unless explicitly described to the contrary, a singular form includes a plural form in the present specification. The word “comprise” and variations such as “comprises” or “comprising,” will be understood to imply the inclusion of stated constituents, steps, operations and/or elements but not the exclusion of any other constituents, steps, operations and/or elements. 
     Hereinafter, a configuration and an acting effect of exemplary embodiments of the present invention will be described in more detail with reference to the accompanying drawings. 
       FIG. 3  is a view schematically showing a method for manufacturing a CMF according to an exemplary embodiment of the present invention; wherein  FIG. 3A  shows a step of providing a substrate  10 ,  FIG. 3B  shows a step of forming a seed metal layer  20 ,  FIG. 3C  shows a step of forming a photo-resist pattern  30 ,  FIG. 3D  shows a step of plating the seed metal layer  20  exposed by the photo-resist pattern  30  with a metal,  FIG. 3E  shows a step of removing the photo-resist pattern  30 ,  FIG. 3F  shows a step of removing the seed metal layer  20  to form first coil patterns  50  and  50   a , and  FIG. 3G  shows a step of performing electroplating on the first coil patterns  50  and  50   a  to form second coil patterns  150  and  150   a.    
     Referring to  FIG. 3 , the method for manufacturing a CMF according to the exemplary embodiment of the present invention includes a step of performing the electroplating on the first coil patterns  50  and  50   a  made of a conductive material  40  to form the second coil patterns  150  and  150   a.    
     Here, the second coil patterns  150  and  150   a  are coil patterns having a cross-sectional area increased as compared to the first coil patterns  50  and  50   a . That is, after the first coil patterns  50  and  50   a  are formed on the substrate  10  by various methods, such as printing, plating, and the like, power is applied to the first coil patterns  50  and  50   a  to perform the electroplating, thereby making it possible to increase the cross-sectional area and decrease a spaced distance between adjacent coils. 
     A method capable of being applied to the case of manufacturing a common mode filter by a photo-resist process will be described in more detail with reference to  FIG. 3 . 
     In the step of providing the substrate  10  shown in  FIG. 3A , various magnetic substrates  10  required for manufacturing the common mode filter may be provided. 
     Then, the step of forming the seed metal layer  20  shown in  FIG. 3B  may be performed in a scheme in which a seed material for performing a subsequent plating process is formed on a surface of the substrate  10  by sputtering, or the like. 
     Next, in the step of forming the photo-resist pattern  30  shown in  FIG. 3C , the photo-resist pattern  30  may be formed by applying a photo-resist material on the seed metal layer  20  and then removing a region to be plated. 
     Then, in the plating process shown in  FIG. 3D , the conductive material  40  may be plated on a partial region of the seed metal layer  20  exposed by the photo-resist pattern  30  formed in the previous step. 
     Thereafter, as shown in  FIG. 3E , the photo-resist pattern  30  is removed, and as shown in  FIG. 3F , the seed metal layer portion  41  positioned beneath the photo-resist pattern  30  is removed, thereby making it possible to form the first coil patterns  50  and  50   a.    
     Next, as shown in  FIG. 3G , the electroplating is performed on the first coil patterns  50  and  50   a  to increase the cross-sectional areas of the coils, thereby making it possible to form the second coil patterns  150  and  150   a.    
     Therefore, the common mode filter capable of decreasing a spaced distance between the adjacent coils and increasing volumes of the coils may be manufactured. As a result, the common mode filter improved in view of characteristics, such as inductance, direct current resistance, and the like, without an increase in the entire size thereof may be implemented. 
     Meanwhile, although not shown, a plurality of insulating layers, coil pattern layers, coil pattern layers, internal electrode terminals, external electrode terminals, a housing, and the like, may be included in the common mode filter in order to complete the common mode filter, which may be easily appreciated by those skilled in the art to which the present invention pertains. Therefore, an additional description thereof will be omitted. 
       FIG. 4  is a view schematically showing a method for manufacturing a CMF according to another exemplary embodiment of the present invention; wherein  FIG. 4A  shows a step of providing a substrate  10 ,  FIG. 4B  shows a step of forming a seed metal layer  20 ,  FIG. 4C  shows a step of forming a photo-resist pattern  30 ,  FIG. 4D  shows a step of plating the seed metal layer  20  exposed by the photo-resist pattern  30  with a metal,  FIG. 4E  shows a step of removing the photo-resist pattern  30 ,  FIG. 4F  shows a step of removing the seed metal layer  20  to form first coil patterns  50  and  50   a ,  FIG. 4G  shows a step of performing electroplating on the first coil pattern  50  and  50   a , and  FIG. 4H  shows a step of performing wet etching on a product of the electroplating to form second coil patterns  250  and  250   a.    
     Since  FIGS. 4A to 4G  are the same as  FIGS. 3A to 3G , an overlapped description of the related content will be omitted. 
     Referring to  FIGS. 4G and 4H , it may be appreciated that when comparing cross-sectional areas of the second coil patterns  150  and  150   a  and the etched second coil patterns  250  and  250   a  with each other, the cross-sectional areas of the etched second coil patterns  250  and  250   a  are slightly decreased as compared to the second coil patterns  150  and  150   a.    
     That is, referring to  FIG. 4H  for describing a state after the electroplating process is performed and the coils are wet-etched using hydrogen peroxide, sulfuric acid, and the like, in the case in which the coils are in contact with each other or a minimum spaced distance is not secured due to excessive performance of the electroplating process, the minimum spaced distance of the coils is secured by the wet etching, thereby making it possible to prevent generation of a short circuit. 
     In addition, since a surface of the coil may remain in a relatively rough state in the case of performing only the electroplating, the wet etching process is performed, thereby making it possible to smooth the surface of the coil. 
       FIG. 5  is a view photographing a cross-section of the CMF according to another exemplary embodiment of the present invention, and  FIG. 6  is a view schematically showing a cross-section of the CMF according to the exemplary embodiment of the present invention. 
     Referring to  FIG. 6 , the common mode filter according to the exemplary embodiment of the present invention generally has an oval shape and may include the second coil pattern  150   a  of which a surface facing the substrate  10  has a flat cross-sectional shape. 
     In this case, when a height h of the second coil pattern  150   a  is excessively high, it may be difficult for a common mode filter formed to have a multi-layer to be slimmed, and when a width w of the second coil pattern  150   a  is excessively wide, it may be difficult to secure sufficient turns in a common mode filter having a limited width 
     Therefore, the cross-sectional shape of the coil pattern may be formed in a range in which a ratio of a long side horizontal to the surface facing the substrate  10  to a short side vertical to the long side is 1.1 to 2:1. 
     Further, when an area of a contact surface between the second coil pattern  150   a  and the substrate  10  is excessively decreased, a phenomenon that the second coil pattern  150   a  is separated from the substrate  10  may occur to deteriorate reliability, and when the area of the contact surface between the second coil pattern  150   a  and the substrate  10  is excessively increased, a cross-sectional area and volume of the second coil pattern  150   a  may be decreased. 
     Therefore, the cross-sectional shape of the coil pattern may be formed in a range in which a ratio of a maximum distance from the long side to the surface facing the substrate  10  to a maximum distance from the long side to an upper surface of the coil pattern is 6.5:3.5 to 5.5:4.5. 
     In addition, a minimum spaced distance between adjacent coils needs to be satisfied in order to secure an insulation property therebetween. Further, the smaller the spaced distance, the larger the volume of the coil pattern. 
     Therefore, the cross-sectional shape of the coil pattern may be formed in a range in which an interval between the adjacent coils becomes 0.15 to 0.45 times of a length of the long side of the coil pattern. 
     Meanwhile, as shown in  FIG. 6 , the second coil pattern  150   a  may be implemented so as to contact an oxide layer  11 , and the like, additionally provided on the substrate  10 . A Fe component may be contained in a ferrite based magnetic substrate  10 . In the case in which the interval between the coils is narrow, since an electric conduction phenomenon may be induced by a component such as Fe, or the like, an oxide layer  11 , or the like, may be provided as an insulating layer in order to prevent this phenomenon. 
       FIG. 7A  is a view schematically showing a state in which a plurality of second coil patterns  150  and  150   a  are connected to a lead wire VL in the method for manufacturing a CMF according to the exemplary embodiment of the present invention,  FIG. 7B  is an enlarged view of the part V of  FIG. 7A , and  FIG. 7C  is a view schematically showing a state in which a dicing process is performed along a dicing line DL of  FIG. 7B . 
     Generally, in order to secure manufacturing efficiency of a common mode filter, a process of allowing a plurality of coil patterns for implementing a single common mode filter to be formed on one layer is performed as shown in  FIG. 7A . 
     Meanwhile, in the method for manufacturing a common mode filter according to the exemplary embodiment of the present invention, the power is applied to the previously formed first coil patterns  50  and  50   a  to perform the electroplating. 
     Here, in the case in which the power is to be applied to each of the coil patters formed on the same layer, since power applying lines having the same number as that of coil patterns formed on one layer are required and each of the power applying lines needs to contact the coil patterns, a manufacturing facility is complicated and manufacturing efficiency is lowered. 
     In order to solve these problems, the power is applied by using a lead wire VL electrically connected to one end of each of the plurality of coil patterns in the present invention. 
     Referring to  FIG. 7B , the lead wire VL enclosing the coil pattern at an outer portion of the coil pattern in a state in which it is spaced from the coil pattern by a predetermined distance may be provided together with the coil pattern. 
     A region in which the lead wire VL is to be formed together with the first coil patterns  50  and  50   a  is exposed by the photo-resist pattern  30  formed on the seed metal layer  20  and a subsequent process is then performed, thereby making it possible to implement the lead wire VL without addition of a manufacturing process or a decrease in manufacture efficiency. 
     In addition, the electroplating is performed by using the lead wire VL as shown in  FIG. 7B , such that the electroplating may be more efficiently performed as compared to the case in which the lead wire VL is not used. 
     Meanwhile, in the case of implementing the lead wire VL so as to have a shape as shown in  FIG. 7B , after a process of forming second coil patterns  150  and  150   a  on one layer are completed, a dicing process may be performed along a dicing line DL as shown in  FIG. 7B , that is, a dicing line DL set so that the lead wire VL is separated from one end of each of a plurality of second coil patterns  150  and  150   a.    
     As set forth above, the method for manufacturing a common mode filter according to the exemplary embodiments of the present invention configured as described above may solve problems according to the related art that there are limitations in increasing cross-sectional area of the coil pattern and at the same time, minimizing the interval between the adjacent coils, in the case of manufacturing the common mode filter by the photo-resist process. 
     That is, the electroplating is additionally performed on the previously formed first coil patterns, thereby making it possible to increase the cross-sectional area of the coil pattern and at the same time, minimize the interval between the adjacent coils. 
     Therefore, the common mode filter improved in view of the characteristics such as the inductance, the DC resistance, and the like, while fulfilling the miniaturization demand may be manufactured. 
     The present invention has been described in connection with what is presently considered to be practical exemplary embodiments. Although the exemplary embodiments of the present invention have been described, the present invention may be also used in various other combinations, modifications and environments. In other words, the present invention may be changed or modified within the range of concept of the invention disclosed in the specification, the range equivalent to the disclosure and/or the range of the technology or knowledge in the field to which the present invention pertains. The exemplary embodiments described above have been provided to explain the best state in carrying out the present invention. Therefore, they may be carried out in other states known to the field to which the present invention pertains in using other inventions such as the present invention and also be modified in various forms required in specific application fields and usages of the invention. Therefore, it is to be understood that the invention is not limited to the disclosed embodiments. It is to be understood that other embodiments are also included within the spirit and scope of the appended claims.