Patent Publication Number: US-8994478-B1

Title: Common mode filter

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2013-0143275, filed with the Korean Intellectual Property Office on Nov. 22, 2013, the disclosure of which is incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a common mode filter. 
     2. Background Art 
     With the recent technological advancement, a growing number of electronic devices, such as mobile phones, home electronic appliances, PCs, PDAs and LCDs, have been changed from analog systems to digital systems. Moreover, owing to the increased amount of processed data, the electronic devices are required to be faster. 
     As the electronic devices are digitized and become faster, the electronic devices can be increasingly sensitive to irritation from outside. That is, any small abnormal voltage or high-frequency noise brought into the internal circuitry of an electronic device from the outside can cause a damage to the circuitry or a signal distortion. 
     Sources of the abnormal voltage and noise that cause the circuitry damage or signal distortion of the electronic device include lightning, discharging of static electricity that has been charged in human body, switching voltage generated in the circuitry, power noise included in the electric source voltage, unnecessary electromagnetic signal or electromagnetic noise, etc. 
     In order to prevent the circuitry damage or signal distortion of the electronic device, a filter needs to be installed to prevent the abnormal voltage and high-frequency noise from being brought into the circuitry. Particularly, a common mode filter is often installed in, for example, a high-speed differential signal line in order to remove common mode noise. 
     The related art of the present invention is disclosed in Korea Patent Publication No. 10-2012-0033644 (laid open on Apr. 9, 2012). 
     SUMMARY 
     The present invention provides a common mode filter that can enhance interface adhesion and effectively prevent penetration of moisture through an interface. 
     An aspect of the present invention provides a common mode filter, which includes: a first dielectric layer having a first groove formed along an outer boundary portion thereof; a second dielectric layer coated on the first dielectric layer so as to cover a first coil laminated on the first dielectric layer, having a first protrusion corresponding to the first groove formed on one surface thereof being in contact with the first dielectric layer, and having a second groove formed on the other surface thereof; and a third dielectric layer coated on the second dielectric layer so as to cover a second coil laminated on the second dielectric layer, having a second protrusion corresponding to the second groove formed on one surface thereof being in contact with the second dielectric layer, and having a third groove formed on the other surface thereof. 
     The first to third grooves can be formed in plural rows on the first to third dielectric layers, respectively. 
     The first to third grooves can be formed in such a way that longitudinal positions thereof are misaligned with one another. 
     Another aspect of the present invention provides a common mode filter, which includes: a first dielectric layer having a first protrusion formed along an outer boundary portion thereof; a second dielectric layer coated on the first dielectric layer so as to cover a first coil laminated on the first dielectric layer, having a first groove corresponding to the first protrusion formed on one surface thereof being in contact with the first dielectric layer, and having a second protrusion formed on the other surface thereof; and a third dielectric layer coated on the second dielectric layer so as to cover a second coil laminated on the second dielectric layer, having a second groove corresponding to the second protrusion formed on one surface thereof being in contact with the second dielectric layer, and having a third protrusion formed on the other surface thereof. 
     The first to third protrusions can be formed in plural rows on the first to third dielectric layers, respectively. 
     The first to third protrusions can be formed in such a way that longitudinal positions thereof are misaligned with one another. 
     The first to third protrusions can be formed with a metal pattern laminated on the first to third dielectric layers, respectively. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a brief illustration of a common mode filter in accordance with an embodiment of the present invention. 
         FIG. 2  shows a longitudinal section of the common mode filter in accordance with an embodiment of the present invention. 
         FIG. 3  shows a transverse section of the common mode filter in accordance with an embodiment of the present invention. 
         FIG. 4  and  FIG. 5  show modification examples of the common mode filter in accordance with an embodiment of the present invention. 
         FIG. 6  shows a longitudinal section of the common mode filter in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, certain embodiments of a common mode filter in accordance with the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention with reference to the accompanying drawings, any identical or corresponding elements will be assigned with same reference numerals, and no redundant description thereof will be provided. 
     Terms such as “first” and “second” can be used in merely distinguishing one element from other identical or corresponding elements, but the above elements shall not be restricted to the above terms. 
     When one element is described to be “coupled” to another element, it does not refer to a physical, direct contact between these elements only, but it shall also include the possibility of yet another element being interposed between these elements and each of these elements being in contact with said yet another element. 
       FIG. 1  is a brief illustration of a common mode filter in accordance with an embodiment of the present invention.  FIG. 2  shows a longitudinal section of the common mode filter in accordance with an embodiment of the present invention.  FIG. 3  shows a transverse section of the common mode filter in accordance with an embodiment of the present invention. 
     As illustrated in  FIGS. 1 to 3 , a common mode filter  1000  in accordance with an embodiment of the present invention can form a coil  110 ,  210  coated with a plurality of dielectric layers  100 ,  200 ,  300  on a substrate  10 , form an external electrode  20  thereon, and form a filling layer  30  having, for example, a magnetic composite filled therein. 
     In such a case, the plurality of dielectric layers  100 ,  200 ,  300  formed in multiple layers can experience interfacial peeling due to stress and decreased reliability due to penetration of moisture because outer boundary portions of the dielectric layers  100 ,  200 ,  300  is exposed to outside. 
     Accordingly, the common mode filter  1000  in accordance with the present embodiment can have grooves  120 ,  220 ,  320  and protrusions  130 ,  230  formed at the respective outer boundary portions of the dielectric layers  100 ,  200 ,  300  to enhance interfacial adhesion and prevent the penetration of moisture into the interface. 
     Specifically, as illustrated in  FIGS. 1 to 3 , the common mode filter in accordance with the present embodiment includes a first dielectric layer  100 , a second dielectric layer  200  and a third dielectric layer  300 . 
     As shown in  FIG. 3 , the first dielectric layer  100  is a portion where a first groove  120  is formed along the outer boundary portion and can insulate the substrate  10  and a first coil  110  and provide smoothness of a surface on which the first coil  110  is laminated. 
     In such a case, the first dielectric layer  100  can be made of a photosensitive dielectric material so that the first groove  120  can be formed on the first dielectric layer  100  through a patterning process. 
     The second dielectric layer  200  can be coated on the first dielectric layer  100  so as to cover the first coil  110  that is laminated on the first dielectric layer  100 , can have a first protrusion  130  corresponding to the first groove  120  formed on one surface thereof that is in contact with the first dielectric layer  100 , and can have a second groove  220  formed on the other surface thereof. 
     That is, as illustrated in  FIG. 2 , when the second dielectric layer  200  is coated on the first dielectric layer  100 , the first protrusion  130  can be inserted in the first groove  120 , and the second groove  220  can be formed on a backside of the first protrusion  130 . 
     In such a case, by coating the second dielectric layer  200  on the first dielectric layer  100  having the first grooved  120  formed thereon, the first protrusion  130  and the second groove  220  can be naturally formed while the second dielectric layer  200  fills in a portion where the first groove  120  is formed. Moreover, as the second dielectric layer  200  is also made of a photosensitive dielectric material, the second groove  220  can be formed on the second dielectric layer  200  more precisely through a patterning process. 
     Meanwhile, the first coil  110  can be made of copper or aluminum, which is highly conductive and workable, and the first coil  110  can be formed through an etching method or an additive method (plating method) using photolithography, but the material and method for forming the first coil  110  shall not be limited to what is described herein and can be variously modified as necessary. 
     The third dielectric layer  300  can be coated on the second dielectric layer  200  so as to cover a second coil  210  that is laminated on the second dielectric layer  200 , can have a second protrusion  230  corresponding to the second groove  220  formed on one surface thereof that is in contact with the second dielectric layer  200 , and can have a third groove  320  formed on the other surface thereof. 
     That is, as shown in  FIG. 2 , when the third dielectric layer  300  is coated on the second dielectric layer  200 , the second protrusion  230  can be inserted in the second groove  220 , and the third groove  320  can be formed on a back side of the second protrusion  230 . Here, the external electrode  20  or the filling layer  30  can be filled in the third groove  320 . 
     In such a case as well, by coating the third dielectric layer  300  on the second dielectric layer  200  having the second grooved  220  formed thereon, the second protrusion  230  and the third groove  320  can be naturally formed while the third dielectric layer  300  fills in a portion where the second groove  220  is formed. Moreover, as the third dielectric layer  300  is also made of a photosensitive dielectric material, the third groove  320  can be formed on the third dielectric layer  300  more precisely through a patterning process. 
     Meanwhile, the second coil  210  can be also made of copper or aluminum, which is highly conductive and workable, and the second coil  210  can be formed through an etching method or an additive method (plating method) using photolithography, but the material and method for forming the second coil  210  shall not be limited to what is described herein and can be variously modified as necessary. Moreover, the second coil  210  can be connected with the first coil  110  through, for example, a via. 
     As such, in the common mode filter  1000  in accordance with the present embodiment, interfacial adhesion can be enhanced because the dielectric layers  100 ,  200 ,  300  are laminated as the first protrusion  130  is inserted in the first groove  120  and the second protrusion  230  is inserted in the second groove  220 . 
     Moreover, in case moisture is penetrated through an interface, the protrusions  130 ,  230  can function as shielding walls to prevent further penetration of the moisture. Particularly, even though there is separation in the interface, the path of moisture penetration on the interface can become extended by the protrusions  130 ,  230 , and thus the penetration of moisture through the interface can be effectively prevented. 
       FIG. 4  and  FIG. 5  show modification examples of the common mode filter in accordance with an embodiment of the present invention. 
     As illustrated in  FIG. 4 , in the common mode filter  1000  in accordance with an embodiment of the present invention, the first groove  120  to third groove  320  can be each formed in plurality on the first dielectric layer  100  to third dielectric layer  300 , respectively. 
     That is, the first groove  120  to third groove  320  can be formed in plural rows on the first dielectric layer  100  to third dielectric layer  300 , respectively, and the first protrusion  130  and the second protrusion  230  can be also formed in plural rows and inserted in the first groove  120  and the second groove  220 , respectively. 
     Through this, the interfacial adhesion can be further enhance, and the penetration of moisture through the interface can be prevented more effectively. 
     Moreover, as illustrated in  FIG. 5 , in the common mode filter  1000  in accordance with an embodiment of the present invention, the first groove  120  to third groove  320  can be formed to misalign with one another. 
     That is, center lines of the first groove  120  to third groove  320  can be placed to be parallel with one another but not on a same longitudinal line in a longitudinal section. 
     Through this, stress may not be concentrated on the first groove  120  to third groove  320 , and thus it becomes possible to prevent the outer boundary portion of the common mode filter  1000  from being vulnerable to stress, and even if separation occurs in the interface, locations of separation can be varied, and thus the separation in the interface can be minimized 
       FIG. 6  shows a longitudinal section of the common mode filter in accordance with another embodiment of the present invention. 
     As illustrated in  FIG. 6 , a common mode filter  2000  in accordance with another embodiment of the present invention also includes a first dielectric layer  101 , a second dielectric layer  210  and a third dielectric layer  301 . 
     The first dielectric layer  101  is a portion where a first protrusion  131  is formed along the outer boundary portion and can insulate the substrate  10  and a first coil  111  and provide smoothness of a surface on which the first coil  111  is laminated. 
     In such a case, an additional dielectric layer made of a photosensitive dielectric material can be coated on top of the first dielectric layer  101 , and then the additional dielectric layer can be patterned, leaving out the first protrusion  131 , to form the first protrusion  131 . 
     The second dielectric layer  201  can be coated on the first dielectric layer  101  so as to cover the first coil  111  that is laminated on the first dielectric layer  101 , can have a first groove  121  corresponding to the first protrusion  131  formed on one surface thereof that is in contact with the first dielectric layer  101 , and can have a second protrusion  231  formed on the other surface thereof. 
     That is, as illustrated in  FIG. 6 , when the second dielectric layer  201  is coated on the first dielectric layer  101 , the first protrusion  131  can be inserted in the first groove  121 , and the second groove  231  can be formed on a backside of the first groove  121 . 
     In such a case, by coating the second dielectric layer  201  on the first dielectric layer  101  having the first grooved  131  formed thereon, the first protrusion  121  and the second groove  231  can be naturally formed while the second dielectric layer  201  covers a portion where the first protrusion  131  is formed. Moreover, an additional dielectric layer made of a photosensitive dielectric material can be also coated on top of the second dielectric layer  201 , and then the additional dielectric layer can be patterned, leaving out the second protrusion  231 , to form the second protrusion  231  more precisely. 
     The third dielectric layer  301  can be coated on the second dielectric layer  201  so as to cover a second coil  211  that is laminated on the second dielectric layer  201 , can have a second groove  221  corresponding to the second protrusion  231  formed on one surface thereof that is in contact with the second dielectric layer  201 , and can have a third protrusion  331  formed on the other surface thereof. 
     That is, as shown in  FIG. 6 , when the third dielectric layer  301  is coated on the second dielectric layer  201 , the second protrusion  231  can be inserted in the second groove  221 , and the third protrusion  331  can be formed on a back side of the second groove  221 . Here, an external electrode  20  or a filling layer  30  can be covered on the third protrusion  331 . 
     In such a case as well, by coating the third dielectric layer  301  on the second dielectric layer  201  having the second protrusion  231  formed thereon, the second groove  221  and the third protrusion  331  can be naturally formed while the third dielectric layer  301  covers a portion where the second protrusion  231  is formed. Moreover, an additional dielectric layer made of a photosensitive dielectric material can be also coated on top of the third dielectric layer  301 , and then the additional dielectric layer can be patterned, leaving out the third protrusion  331 , to form the third protrusion  331  more precisely. 
     As such, in the common mode filter  2000  in accordance with the present embodiment, interfacial adhesion can be enhanced because the dielectric layers  101 ,  201 ,  301  are laminated as the first protrusion  131  is inserted in the first groove  121  and the second protrusion  231  is inserted in the second groove  221 . 
     Moreover, in case moisture is penetrated through an interface, the protrusions  131 ,  231 ,  331  can function as shielding walls to prevent further penetration of the moisture. Particularly, even though there is separation in the interface, the path of moisture penetration on the interface can become extended by the protrusions  131 ,  231 ,  331 , and thus the penetration of moisture through the interface can be effectively prevented. 
     In the common mode filter  2000  in accordance with the present embodiment, the first protrusion  131  to third protrusion  331  can be formed with a metal pattern laminated on the first dielectric layer  101  to third dielectric layer  301 , respectively. 
     That is, instead of patterning the additional dielectric layer as described above, the first protrusion  131  to third protrusion  331  can be formed by laminating the metal pattern on the dielectric layers  101 ,  201 ,  301 , similarly to the way the coils  111 ,  211  are formed. 
     As a result, the processes for forming the first protrusion  131  to third protrusion  331  can be simplified by, for example, forming the first protrusion  131  to third protrusion  331  simultaneously with the coils  111 ,  211  or reducing the coating and patterning processes to the lamination process, and thus the common mode filter  2000  in accordance with the present embodiment can be manufactured more easily. 
     Except for the above-described elements and configurations, the common mode filter  2000  in accordance with another embodiment of the present embodiment has the same or similar elements and configurations as those of the common mode filter  1000  in accordance with an embodiment of the present embodiment, and thus these redundant elements and configurations will not be described herein. 
     Although certain embodiments of the present invention have been described, it shall be appreciated that there can be a very large number of permutations and modification of the present invention by those who are ordinarily skilled in the art to which the present invention pertains without departing from the technical ideas and scope of the present invention, which shall be defined by the claims appended below. 
     It shall be also appreciated that many other embodiments than the embodiments described above are included in the claims of the present invention.