Common mode filter and method of manufacturing the same

Abstract

A common mode filter having heterogeneous laminates includes a first magnetic layer, a nonmagnetic insulating substrate, a second magnetic layer, a first coil layer, and a second coil layer. The second magnetic layer is formed on the nonmagnetic insulating substrate, between the nonmagnetic insulating substrate and the first magnetic layer. The first coil layer is disposed between the first magnetic layer and the second magnetic layer, and includes a first coil. The second coil layer is disposed between the first magnetic layer and the second magnetic layer, and includes a second coil. The first and second coil layers are separated from each other, and the first and second coils are magnetically coupled to each other.

1 . A common mode filter having heterogeneous laminates, comprising:
 a first magnetic layer;   a nonmagnetic insulating substrate;   a second magnetic layer formed on the nonmagnetic insulating substrate, between the first magnetic layer and the nonmagnetic insulating substrate;   a first coil layer disposed between the first magnetic layer and the second magnetic layer, comprising a first coil; and   a second coil layer disposed between the first magnetic layer and the second magnetic layer, comprising a second coil, wherein the first and second coil layers are separated from each other, and the first and second coils are magnetically coupled to each other.   
     
     
         2 . The common mode filter of  claim 1 , further comprising a flattening insulation layer covering the second magnetic layer. 
     
     
         3 . The common mode filter of  claim 2 , wherein the flattening insulation layer comprises polyimide, epoxy, or benzocyclobutene. 
     
     
         4 . The common mode filter of  claim 1 , wherein the second magnetic layer partially or entirely covers the nonmagnetic insulating substrate. 
     
     
         5 . The common mode filter of  claim 1 , wherein the second magnetic layer comprises a plurality of magnetic material pieces separated from each other. 
     
     
         6 . The common mode filter of  claim 1 , further comprising an adhesive configured to bond the second magnetic layer to the nonmagnetic insulating substrate. 
     
     
         7 . The common mode filter of  claim 1 , wherein the second magnetic layer and the nonmagnetic insulating substrate are diffusion bonded. 
     
     
         8 . The common mode filter of  claim 1 , wherein the nonmagnetic insulating substrate comprises aluminum oxide, aluminum nitride, glass, or quartz crystal. 
     
     
         9 . The common mode filter of  claim 1 , wherein the second magnetic layer comprises nickel zinc ferrite material or manganese zinc ferrite material. 
     
     
         10 . The common mode filter of  claim 1 , wherein the second magnetic layer comprises polymer. 
     
     
         11 . The common mode filter of  claim 10 , wherein the polymer comprises polyimide or epoxy. 
     
     
         12 . The common mode filter of  claim 1 , wherein the first magnetic layer comprises magnetic powder and a polymer, wherein the magnetic powder comprises nickel zinc ferrite or manganese zinc ferrite, and the polymer comprises polyimide, epoxy, or benzocyclobutene. 
     
     
         13 . The common mode filter of  claim 1 , comprising:
 a first lead layer formed on the second magnetic layer, comprising a first lead;   a first insulating layer formed between the first lead layer and the first coil layer, comprising a first through hole formed through the first insulating layer, wherein one end of the first lead electrically connects to the first coil via the first through hole, and another end of the first lead extends adjacent to an edge of the insulating layer;   a second insulating layer formed between the first coil layer and the second coil layer;   a third insulating layer formed on the second coil layer, comprising a second through hole;   a second lead layer formed on the third insulating layer, comprising a second lead, which comprises one end electrically connecting to the second coil via the second through hole and another end extending adjacent to an edge of the third insulating layer; and   a fourth insulating layer formed between the second lead layer and the first magnetic layer.   
     
     
         14 . The common mode filter of  claim 13 , wherein one of the first, second, third, and fourth insulating layers comprises polyimide, epoxy, or benzocyclobutene. 
     
     
         15 . The common mode filter of  claim 13 , wherein one of the first coil, the second coil, the first lead, and the second lead comprises silver, palladium, aluminum, chromium, nickel, titanium, gold, copper, platinum, or an alloy thereof. 
     
     
         16 . A method of manufacturing a common mode filter having heterogeneous laminates, the method comprising the steps of:
 providing a nonmagnetic insulating substrate comprising a major surface;   forming a magnetic layer on part or all of the major surface;   forming a first lead on the magnetic layer;   forming a first insulating layer covering the first lead;   forming a first through hole penetrating through the first insulating layer;   forming a first coil on the first insulating layer, wherein the first coil electrically connects to the first lead via the first through hole;   forming a second insulating layer covering the first coil;   forming a second coil on the second insulating layer;   forming a third insulating layer covering the second coil;   forming a second through hole penetrating through the third insulating layer;   forming a second lead on the third insulating layer, wherein the second lead electrically connects to the second coil via the second through hole;   forming a fourth insulating layer covering the second lead; and   depositing a first magnetic material on the fourth insulating layer.   
     
     
         17 . The method of  claim 16 , wherein the step of forming a magnetic layer on part or all of the major surface comprises a step of bonding the magnetic layer to the nonmagnetic insulating substrate by an adhesive. 
     
     
         18 . The method of  claim 16 , wherein the step of forming a magnetic layer on part or all of the major surface comprises the steps of:
 depositing a second magnetic material on the nonmagnetic insulating substrate; and   co-firing the second magnetic material and the nonmagnetic insulating substrate.   
     
     
         19 . The method of  claim 16 , wherein the step of forming a magnetic layer on part or all of the major surface comprises the steps of:
 mixing magnetic powder and a polymer to obtain a mixture; and   depositing the mixture on the nonmagnetic insulating substrate.   
     
     
         20 . The method of  claim 19 , wherein the magnetic powder comprises nickel zinc ferrite or manganese zinc ferrite, and the polymer comprises polyimide, epoxy, or benzocyclobutene. 
     
     
         21 . The method of  claim 16 , further comprising a step of forming a flattening insulation layer on the magnetic layer.