Patent Publication Number: US-8981889-B2

Title: Common mode filter with ESD protection pattern built therein

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. 10-2012-0094776, entitled “Common Mode Filter with ESD Protection Pattern Built Therein” filed on Aug. 29, 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 common mode filter with a electrostatic discharge (ESD) protection pattern built therein, and more particularly, to a common mode filter with an ESD protection pattern built therein, in which an external electrode terminal of the common mode filter is divided into a first external electrode terminal and a second external electrode terminal, and the ESD protection pattern is built therebetween so that a function of the common mode filter and a static eliminating function are integrated into a single electronic component to be implemented, and therefore a mounting area is reduced at the time of application of an SET product. 
     2. Description of the Related Art 
     In recent years, electronic apparatuses such as mobile phones, home appliances, personal computers (PC), personal digital assistants (PDA), liquid crystal displays (LCD), navigations, and the like have been gradually digitalized with faster speeds. Since the electronic apparatuses are sensitive to external stimulation, there occurs a case in which the circuits are damaged or signals are distorted when slightly abnormal voltage and high frequency noise flow into an internal circuit of the electronic apparatus from the outside. 
     As the causes of the abnormal voltage and the noise, a switching voltage generated in the circuit, a power source noise included in a power supply voltage, unnecessary electromagnetic signals or noises, or the like may be given, and as a means for preventing the abnormal voltage and the high frequency noise from flowing into the circuit, a filter may be used. 
     In a general differential signal transmission system, together with a common mode noise filter for removing common mode noises, a passive component such as a diode, a varistor, or the like has to be separately used to prevent electro static discharge (Hereinafter, referred to as “ESD”) that may occur in an input/output terminal. 
     In this manner, when the separate passive component is used in the input/output terminal so as to correspond to the ESD, a mounting area and manufacturing costs may be increased, and distortion of signals may occur. 
     For example, in order to suppress the ESD using the varistor, internal electronic components of the electronic apparatus are protected in such a manner that an end of the varistor is connected to the input/output terminal and the other end thereof is connected to a ground terminal. 
     However, the varistor acts as a capacitor in a normal operation state of the electronic apparatus to which a transient voltage is not applied. Since the capacitor has a capacitance value that changes at a high frequency, there occurs a problem such as occurrence of signal distortion, or the like when an element of the varistor is used in a data input/output terminal at a high frequency or a high speed, or the like. 
     Meanwhile, a protection element such as the common mode noise filter, the varistor, or the like may be formed in a rectangular parallelepiped shape, and an internal electrode may be provided inside the protection element, and an external electrode that is connected with the internal electrode may be provided outside the protection element. 
     In addition, a ground electrode may be provided inside the protection element, and another external electrode that is connected with the ground electrode may be provided outside the protection element. 
     However, the external electrode that is connected with the internal electrode is provided on one side and the other side of the element, and the external electrode that is connected with the ground electrode is provided on a side surface of the element in a direction that intersects with the one side and the other side of the element. 
     That is, the external electrode that is connected with the internal electrode and the external electrode that is connected with the ground electrode are formed respectively on mutually different side surfaces. 
     Accordingly, the external electrode is formed on all side surfaces of the element. In addition, in order to mount the element on a printed circuit board, a space for connecting the external electrode and a wiring printed on the printed circuit board is required. 
     However, in a structure of the element according to the related art in which the external electrode is provided on all side surfaces of the element, there is a limitation in securing a spare space of the printed circuit board, and therefore design of the printed circuit board is difficult. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a common mode filter with an ESD protection pattern built therein, in which an external electrode terminal of the common mode filter is divided into a first external electrode terminal and a second external electrode terminal, and the ESD protection pattern is built therebetween so that a function of the common mode filter and a static eliminating function are integrated into a single electronic component to be implemented, and therefore a mounting area is reduced at the time of application of an SET product. 
     According to an exemplary embodiment of the present invention, there is provided a common mode filter with an electrostatic discharge (ESD) protection pattern built therein, being characterized in that an external electrode terminal of the common mode filter is divided into a first external electrode terminal and a second external electrode terminal, and an ESD protection pattern is built between the first and second external electrode terminals so that a function of the common mode filter and a static eliminating function are integrated into one electronic component. 
     According to another exemplary embodiment of the present invention, there is provided a common mode filter with an ESD protection pattern built therein, including: a base substrate that is made of an insulating material; a first insulating layer that is formed on the base substrate; a coil-shaped internal electrode that is formed on the first insulating layer; a second insulating layer that is formed on the internal electrode; a first external electrode terminal that is formed on the second insulating layer; a first ferrite resin layer that is formed on the second insulating layer and receives the first external electrode terminal; an ESD protection pattern that is formed on the first external electrode terminal; a second external electrode terminal that is formed on the ESD protection pattern; and a second ferrite resin layer that is formed on the first ferrite resin layer and receives the second external electrode terminal. 
     In addition, the base substrate may be made of ferrite. 
     Besides, the first and second insulating layers may be made of any one selected from polyimide, epoxy resin, benzo cyclobutene (BCB), and other high-molecular polymers. 
     Further, the internal electrode may have a multi-layered structure of which a plurality of layers are spaced apart from each other by a predetermined interval. 
     Furthermore, a portion in which the ESD protection pattern of the first external electrode terminal is formed may be formed as concavo-convex shape, or branched into a plurality of branch lines, and a plurality of ESD protection patterns may be formed to correspond one-to-one to each of the plurality of branch lines. 
     Moreover, the ESD protection pattern may be a printed pattern. 
     Also, the ESD protection pattern may be made of a material in which at least one conductive material selected from ruthenium oxide (RuO 2 ), platinum (Pt), palladium (Pd), antigen (Ag), aurum (Au), nickel (Ni), chromium (Cr), tungsten (W), and the like is mixed in an organic material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a conceptual diagram showing a cross-sectional structure of a common mode filter with an electrostatic discharge (ESD) protection pattern built therein according to an embodiment of the present invention; 
         FIGS. 2A to 2F  are conceptual diagrams sequentially showing a process of manufacturing a common mode filter with an ESD protection pattern built therein according to an embodiment of the present invention; 
         FIG. 3  is a photograph showing a structure of an internal electrode according to an embodiment of the present invention; 
         FIG. 4  is a plan view showing a first external electrode terminal and an ESD protection pattern according to an embodiment of the present invention; 
         FIG. 5  is a plan view showing a second external electrode terminal according to the present embodiment of the present invention; and 
         FIGS. 6 and 7  are conceptual diagrams showing a modified example of the first external electrode terminal and the ESD protection pattern according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, details with respect to a preferred embodiment of the present invention will be described with reference to the accompanying drawings as below. 
       FIG. 1  is a conceptual diagram showing a cross-sectional structure of a common mode filter with an electrostatic discharge (ESD) protection pattern built therein according to an embodiment of the present invention, and  FIGS. 2A to 2F  are conceptual diagrams sequentially showing a process of manufacturing the common mode filter with an ESD protection pattern built therein according to an embodiment of the present invention. 
     Referring to  FIGS. 1 and 2 , the common mode filter with an ESD protection pattern built therein according to an embodiment of the present invention includes a base substrate  10 , a first insulating layer  20 , an internal electrode  30 , a second insulating layer  40 , a first external electrode terminal  50 , an ESD protection pattern  70 , a first ferrite resin layer  60 , a second external electrode terminal  80 , and a second ferrite resin layer  90 . 
     As shown in  FIG. 2A , the first insulating layer  20  is formed on the base substrate  10 . 
     In this instance, the base substrate  10  may be manufactured using an insulating material, and, for example, a ferrite material may be used. 
     In addition, the first insulating layer  20  may select and use one of polyimide, epoxy resin, benzo cyclobutene (BCB), or other high-molecular polymers, and may adjust an impedance by adjusting a thickness of a spin coating layer. 
     In addition, the internal electrode  30  and the second insulating layer  40  are formed on the first insulating layer  20 , as shown in  FIG. 2B . 
     In this instance, the internal electrode  30  may be formed into a coil shape, as shown in  FIG. 3 , and an end of the coil shape forms a drawing end  31  that is connected to the external electrode terminal side, and the other end thereof forms a connection end  32  that grounds between a plurality of internal electrodes  30 . 
     In addition, the second insulating layer  40  may select and use one of polyimide, epoxy resin, benzo cyclobutene (BCB), or other high-molecular polymers, and may be formed by a photo-via method. 
     Here, the photo-via method refers to a method in which a special developing ink containing insulating resin is used as an insulating layer and is laminated. 
     In this instance, the internal electrode  30  may have a multi-layered structure in which a plurality of layers are spaced apart from each other by a predetermined interval, and a second insulating layer  40  is formed so as to completely receive the internal electrode  30 . 
     In addition, as shown in  FIG. 2C , the first external electrode terminal  50  is formed on the second insulating layer  40 . In this instance, the first external electrode terminal  50  is connected to the drawing end  31  of the internal electrode  30  shown in  FIG. 3 , and referring to  FIGS. 3 and 4 , the first external electrode terminals  50  that are connected to each drawing end  31  are disposed one by one at four edges in four directions. 
     In addition, as shown in  FIG. 2D , the first external electrode terminal  50  protrudes by a predetermined height, and the first ferrite resin layer  60  is formed in accordance with the height of the protruding first external electrode terminal  50 . In addition, the first ferrite resin layer  60  is formed on the second insulating layer  40  and receives the first external electrode terminal  50 . 
     In addition, as shown in  FIG. 2E , the ESD protection pattern  70  is formed on the first external electrode terminal  50 . 
     In this instance, the ESD protection pattern  70  may be made of a material in which at least one conductive material selected from titanium dioxide (TiO 2 ), ruthenium oxide (RuO 2 ), platinum (Pt), palladium (Pd), antigen (Ag), aurum (Au), nickel (Ni), chromium (Cr), tungsten (W), and the like is mixed in an organic material. 
     The ESD protection pattern  70  according to an embodiment of the present invention described above forms a pattern in a printing method, and this has an effect that improves the following problem in the existing method. 
     For example, adhesion of titanium dioxide (TiO 2 ) should be gained sufficiently in order to form the ESD protection pattern (for example, (TiO 2 ) on an electrode terminal (for example, copper (Cu)) in the existing method, and for achieving this, a process for increasing adhesion between the electrode terminal (Cu) and the ESD protection pattern (TiO 2 ) as well as adhesion between the ESD protection pattern (TiO 2 ) and the ferrite resin should precede, and when the adhesion does not increase, a problem occurs in that the ESD protection pattern (TiO 2 ) peels off during the process. 
     To overcome this problem, a surface treatment process using a plasma cleaning method (plasma activation) should be performed in the existing method, thereby simultaneously increasing the adhesion of the ferrite resin layer  60  and electrode terminal (Cu) layer. 
     In addition, in the existing method, the ESD protection pattern (TiO 2 ) is formed through etching, but a patterning operation by etching is difficult, and the use of an etching solution is restricted. 
     In this instance, the etching is performed using the etching solution in which a small amount of phosphoric acid or sulfuric acid is mixed. Here, when the amount of phosphoric acid or sulfuric acid is excessively mixed, a problem occurs in that a magnetic material of the ferrite resin layer  60  is damaged. 
     In addition, in order to repeatedly form the external electrode on the patterned ESD protection pattern (TiO 2 ), the plasma cleaning method should be performed so as to increase the adhesion. 
     In addition, in the existing method, there is a problem in that the ferrite resin that does not react to a plating solution should be used so that the ferrite resin layer is prevented from contacting the plating solution and reacting to the plating solution at the time of plating of the external electrode. 
       FIG. 4  is a plan view showing a first external electrode terminal and an ESD protection pattern according to an embodiment of the present invention. Referring to  FIG. 4 , the ESD protection pattern  70  is respectively printed on both end portions of the first external electrode terminals  50  of which each pair is disposed so as to face each other. 
     As shown in  FIG. 2F , the second external electrode terminal  80  and the second ferrite resin layer  90  may be sequentially formed. 
       FIG. 5  is a plan view showing a second external electrode terminal according to an embodiment of the present invention. 
     Referring to  FIG. 5 , each of a plurality of second external electrode terminals  80  is respectively formed, and on the ESD protection pattern  70  and the first external electrode terminal  50 , and in this instance, the second external electrode terminal  80  formed on the ESD protection pattern  70  is formed by connecting each pair of the ESD protection patterns  70 . 
       FIGS. 6 and 7  are conceptual diagrams showing a modified example of a first external electrode terminal and an ESD protection pattern according to an embodiment of the present invention. A portion in which the ESD protection pattern  70  of the first external electrode terminal  50  is formed may be formed as a concavo-convex  51  shape or branched into a plurality of branch lines  52 . 
     In this instance, the concavo-convex  51  shape may be shaped in a sharp waveform, and the number of the branch lines  52  may be determined in a range of 2 to 6. 
     In this instance, when the plurality of branch lines  52  are formed, a plurality of ESD protection patterns  70  may be formed to correspond one-to-one with each of the branch lines  52 . 
     Therefore, a grounding surface area between the first external electrode terminal  50  and the ESD protection pattern  70  is increased, thereby further improving an electrostatic discharging function. 
     In addition, the second ferrite resin layer  90  in which the second external electrode terminals  80  is received is formed on the first ferrite resin layer  60 . 
     In this instance, the first and second ferrite resin layers  60  and  90  are formed into a single layer, but are separately formed in two stages, so that the ESD protection pattern  70  is built between the first and second external electrode terminals. 
     As described above, according to the embodiments of the present invention, the external electrode terminal of the common mode filter is divided into the first external electrode terminal and the second external electrode terminal, and the ESD protection pattern is built therebetween so that a function of the common mode filter and a static eliminating function are integrated into a single electronic component to be implemented, and therefore a mounting area is reduced at the time of application of an SET product, thereby contributing to miniaturization of the product. 
     Although the exemplary embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Therefore, the detailed description of the present invention does not intend to limit the present invention to the disclosed embodiments. Further, it should be appreciated that the appended claims may include even another embodiment.