# US 2014/0191838 A1 · Common mode noise filter and production method therefor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191838 A1 - Document ID: US20140191838A1 - Status: Published application - Kind: A1 - Application number: 14/238,181 - Filed: 2012-09-13 - Published: 2014-07-10 - Earliest claimed: 2011-09-15 - Assignees: Panasonic Corporation - Inventors: Noritaka Yoshida - Web page: https://patentgrep.com/patent/US20140191838A1 ## CPC - H01F 27/2804: {Printed windings} - H01F 17/0013: {with stacked layers} - H01F 38/48: {Common mode inductor for reducing or eliminating common mode noise on parallel lines} - H01F 2017/0066: {with a magnetic layer} - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES ## Abstract A common mode noise filter includes a first insulating layer, a first coil conductor on an upper surface of the first insulating layer, a second coil conductor on a lower surface of the first insulating layer, a second insulating layer on the upper surface of the first insulating layer to cover the first coil conductor, a third insulating layer on a lower surface of the second insulating layer to cover the second coil conductor. The first insulating layer contains glass and inorganic filler, and contains pores dispersed therein. The second insulating layer covers the first coil conductor, contains glass and inorganic filler, and contains pores dispersed therein. The third insulating layer covers the second coil conductor, contains glass and inorganic filler, and contains pores dispersed therein. This common mode noise filter has excellent high-frequency characteristics at a high yield rate. ## Claims ### Claim 1 A common mode noise filter comprising: a first insulating layer containing glass and inorganic filler, the first insulating layer containing a plurality of pores dispersed therein; a first coil conductor disposed on an upper surface of the first insulating layer; a second coil conductor disposed on a lower surface of the first insulating layer, the second coil conductor facing the first coil conductor across the first insulating layer; a second insulating layer disposed on the upper surface of the first insulating layer to cover the first coil conductor, the second insulating layer containing glass and inorganic filler, the second insulating layer containing a plurality of pores dispersed therein; a third insulating layer disposed on the lower surface of the second insulating layer to cover the second coil conductor, the third insulating layer containing glass and inorganic filler, third insulating layer containing a plurality of pores dispersed therein; a first magnetic oxide layer disposed above an upper surface of the second insulating layer; and a second magnetic oxide layer disposed below a lower surface of the third insulating layer such that the first insulating layer, the second insulating layer, and the third insulating layer are provided between the first magnetic oxide layer and the second magnetic oxide layer. ### Claim 2 (depends on 1) The common mode noise filter according to claim 1, wherein the first magnetic oxide layer is disposed on the upper surface of the second insulating layer. ### Claim 3 (depends on 2) The common mode noise filter according to claim 2, wherein the second magnetic oxide layer is disposed on the lower surface of the third insulating layer. ### Claim 4 (depends on 1) The common mode noise filter according to claim 1, further comprising: a first leading electrode disposed on the upper surface of the second insulating layer and connected electrically to at least one of the first coil conductor and the second coil conductor; and a fourth insulating layer disposed on the upper surface of the second insulating layer to cover the first leading electrode, the fourth insulating layer containing glass component, wherein the first magnetic oxide layer is disposed on an upper surface of the fourth insulating layer. ### Claim 5 (depends on 4) The common mode noise filter according to claim 4, further comprising: a second leading electrode disposed on the lower surface of the third insulating layer and connected electrically to at least one of the first coil conductor and the second coil conductor; and a fifth insulating layer disposed on the lower surface of the third insulating layer to cover the second electrode, the fifth insulating layer containing glass component, wherein the second magnetic oxide layer is disposed on a lower surface of the fifth insulating layer. ### Claim 6 A common mode noise filter comprising: a first insulating layer containing glass and inorganic filler, the first insulating layer containing a plurality of first pores dispersed therein; a first coil conductor provided in the first insulating layer so as not to be exposed to an upper surface and a lower surface of the first insulating layer; a second coil conductor provided in the first insulating layer so as not to be expose to the upper surface and the lower surface of the first insulating layer, the second coil conductor facing the first coil conductor across a part of the first insulating layer; a second insulating layer disposed on the upper surface of the first insulating layer, the second insulating layer containing glass and inorganic filler; a third insulating layer disposed on the lower surface of the first insulating layer such that the first insulating layer is provided between the second insulating layer and the third insulating layer, the third insulating layer containing glass and inorganic filler; a first magnetic oxide layer disposed above an upper surface of the second insulating layer; and a second magnetic oxide layer disposed below a lower surface of the third insulating layer, wherein a total volume of pores contained in the second insulating layer per unit volume and a total volume of pores contained in the third insulating layer per unit volume are smaller than a total volume of the first pores in the first insulating layer per unit volume. ### Claim 7 (depends on 6) The common mode noise filter according to claim 6, wherein the second insulating layer contains substantially no pore dispersed therein, and wherein the third insulating layers contains substantially no pore dispersed therein. ### Claim 8 (depends on 1, 6) The common mode noise filter according to claim 1 or 6, wherein thicknesses of the second insulating layer and the third insulating layer are not smaller than 5 μm. ### Claim 9 (depends on 1, 6) The common mode noise filter according to claim 1 or 6, wherein the first insulating layer, the second insulating layer, and the third insulating layer comprise alkaline earth metal element. ### Claim 10 (depends on 1, 6) The common mode noise filter according to claim 1 or 6, wherein the glass contained in the first insulating layer and the glass contained in the second insulating layer are made of a same material, wherein the glass contained in the first insulating layer and the glass contained in the third insulating layer are made of a same material, wherein the inorganic filer contained in the first insulating layer and the inorganic filer contained in the second insulating layer are made of a same material, and wherein the inorganic filler contained in the first insulating layer and the inorganic filer contained in the third insulating layer are made of a same material. ### Claim 11 (depends on 1, 6) The common mode noise filter according to claim 1 or 6, wherein the first insulating layer, the second insulating layer, and the third insulating layer contain borosilicate glass and silica filler. ### Claim 12 A method of manufacturing a common mode noise filter, comprising: providing a first insulating sheet containing glass, inorganic filler, inorganic foaming agent, and organic binder; providing a second insulating sheet containing glass, inorganic filler, inorganic foaming agent, and organic binder; providing a third insulating sheet containing glass, inorganic filler, inorganic forming agent, and organic binder; providing a first magnetic oxide sheet mainly made of magnetic material and containing organic binder; preparing a second magnetic oxide sheet mainly made of magnetic material and containing organic binder; forming a laminated body which includes a first coil conductor disposed on an upper surface of the first insulating sheet, the second insulating sheet disposed on the upper surface of the first insulating sheet for covering the first coil conductor, a second coil conductor disposed on a lower surface of the first insulating sheet, the third insulating layer disposed on the lower surface of the first insulating sheet for covering the second coil conductor, the first magnetic oxide sheet disposed above an upper surface of the second insulating sheet, and the second magnetic oxide sheet disposed below a lower surface of the third insulating sheet, such that the first insulating sheet, the second insulating sheet, and the third insulating sheet are provided between the first magnetic oxide sheet and the second magnetic oxide sheet, obtaining a fired body by firing the laminated body for producing gas from the inorganic foaming agent contained in the first insulating sheet, the inorganic foaming agent contained in the second insulating sheet, and the inorganic foaming agent contained in the third insulating sheet as to form a plurality of pores in each of the first insulating sheet, the second insulating sheet, and the third insulating sheet; and providing an external terminal electrode on the fired body. ### Claim 13 A method of manufacturing a common mode noise filter, comprising: providing a first insulating sheet layer, a second insulating sheet layer, and a third insulating sheet layer that contain glass, inorganic filler, inorganic foaming agent, and organic binder and that are configured to be laminated to provide a first insulating sheet; providing a second insulating sheet containing glass, inorganic filler, and organic binder; providing a third insulating sheet containing glass, inorganic filler, and organic binder; providing a first magnetic oxide sheet mainly made of magnetic material and containing organic binder; providing a second magnetic oxide sheet mainly made of magnetic material and containing organic binder; forming a laminated body which includes a first coil conductor disposed on an upper surface of the first insulating-sheet layer. the second insulating sheet layer disposed on the upper surface of the first insulating sheet layer to cover the first coil conductor. a second coil conductor disposed on a lower surface of the first insulating sheet layer, the third insulating sheet layer disposed on the lower surface of the first insulating sheet layer to cover the second coil conductor, the second insulating layer disposed on an upper surface of the second insulating-sheet layer, the third insulating sheet disposed on a lower surface of the third insulating sheet layer, such that the first insulating sheet layer, the second insulating sheet layer, and the third insulating sheet layer are sandwiched between the second insulating sheet and the third insulating sheet; the first magnetic oxide sheet disposed above an upper surface of the second insulating sheet, and the second magnetic oxide sheet disposed below a lower surface of the third insulating sheet, such that the first insulating sheet layer, the second insulating sheet layer, and the third insulating sheet layer, the second insulating sheet, and the third insulating sheet are sandwiched between the first magnetic oxide sheet and the second magnetic oxide sheet; and obtaining a fired body by firing the laminated body to generate gas from the inorganic foaming agent contained in the first insulating sheet layer, the second insulating sheet layer, and the third insulating sheet layer, as to form a plurality of pores in each of the first insulating sheet layer, the second insulating sheet layer, and the third insulating sheet layer; and providing an external terminal electrode on the fired body. ### Claim 14 (depends on 12, 13) The method according to claim 12 or 13, wherein the inorganic foaming agent contains alkaline earth carbonate.