Method of Constructing Inductors and Transformers

Abstract

An embodiment of the invention relates to an apparatus including a magnetic device and a related method. A multilayer substrate is constructed with a winding formed in a metallic layer, an electrically insulating layer above the metallic layer, and a via formed in the electrically insulating layer to couple the winding to a circuit element positioned on the multilayer substrate. A depression is formed in the multilayer substrate, and a polymer solution, preferably an epoxy, containing a ferromagnetic component such as nanocrystaline nickel zinc ferrite is deposited within a mold positioned on a surface of the multilayer substrate above the winding and in the depression. An integrated circuit electrically coupled to the winding may be located on the multilayer substrate. The multilayer substrate may be a semiconductor substrate or a printed wiring board, and the circuit element may be an integrated circuit formed on the multilayer substrate.

In the claims: 
     
         1 . An apparatus, comprising:
 a multilayer substrate comprising a first winding of a magnetic device formed in a first metallic layer of the multilayer substrate;   a first electrically insulating layer formed above the first metallic layer;   a first via formed in the first electrically insulating layer, wherein the first via is configured to couple the first winding to a connection for a circuit element positioned on the multilayer substrate;   a depression formed in the multilayer substrate; and   a ferromagnetic material disposed on a surface of the multilayer substrate above the first winding and in the depression, wherein the first winding is not completely encircled by the ferromagnetic material.   
     
     
         2 . (canceled) 
     
     
         3 . The apparatus as claimed in  claim 1 , wherein the ferromagnetic material comprises nanocrystaline nickel zinc ferrite. 
     
     
         4 . The apparatus as claimed in  claim 1 , wherein the depression incompletely penetrates the multilayer substrate. 
     
     
         5 . (canceled) 
     
     
         6 . The apparatus as claimed in  claim 1 , wherein the multilayer substrate comprises a printed wiring board. 
     
     
         7 . The apparatus as claimed in  claim 1 , further comprising an integrated circuit located on the multilayer substrate and electrically coupled to the first winding. 
     
     
         8 . The apparatus as claimed in  claim 7 , wherein the apparatus comprises a power conversion device. 
     
     
         9 . The apparatus as claimed in  claim 1 , further comprising:
 a second insulating layer formed on the multilayer substrate below the first metallic layer;   a second winding of the magnetic device formed in a second metallic layer of the multilayer substrate, wherein the second metallic layer is formed on the multilayer substrate below the second insulating layer; and   a second via formed in the second insulating layer, wherein the second via electrically couples the second winding to the first winding.   
     
     
         10 . The apparatus as claimed in  claim 9 , wherein the first via and the second via are metallic vias. 
     
     
         11 . The apparatus as claimed in  claim 9 , further comprising:
 a third insulating layer formed on the multilayer substrate below the second metallic layer;   a third metallic layer formed on the multilayer substrate below the third insulating layer, wherein the third metallic layer forms a further winding of the magnetic device electrically insulated from the first winding; and   a third via formed in the third insulating layer, wherein the third via provides an electrical coupling of the further winding to a further connection configured to be coupled to a further circuit element located on the multilayer substrate.   
     
     
         12 . The apparatus as claimed in  claim 11 , wherein the multilayer substrate comprises a semiconductor substrate, and wherein the circuit element comprises an integrated circuit formed on the multilayer substrate. 
     
     
         13 . A method of forming an apparatus, the method comprising:
 forming a first metallic layer of a multilayer substrate;   forming a first winding of a magnetic device in the first metallic layer;   forming a first electrically insulating layer above the first metallic layer;   forming a first via in the first electrically insulating layer to couple the first winding to a connection configured to be coupled to a circuit element;   forming a depression in the multilayer substrate; and   forming a ferromagnetic material on a surface of the multilayer substrate above the first winding and in the depression, wherein the first winding is not completely encircled by the ferromagnetic material.   
     
     
         14 . (canceled) 
     
     
         15 . The method as claimed in  claim 13 , wherein the ferromagnetic material comprises nanocrystaline nickel zinc ferrite. 
     
     
         16 . The method as claimed in  claim 13 , wherein the depression incompletely penetrates the multilayer substrate. 
     
     
         17 . (canceled) 
     
     
         18 . The method as claimed in  claim 13 , wherein the multilayer substrate comprises a printed wiring board. 
     
     
         19 . The method as claimed in  claim 13 , wherein the apparatus comprises a power conversion device. 
     
     
         20 . The method as claimed in  claim 13 , further comprising:
 forming a second insulating layer on the multilayer substrate below the first metallic layer;   forming a second metallic layer on the multilayer substrate below the second insulating layer;   forming a second winding of the magnetic device in the second metallic layer; and   forming a second via in the second insulating layer to electrically couple the second winding to the first winding.   
     
     
         21 . A power converter, comprising:
 a magnetic circuit element comprising
 a multilayer substrate comprising a first winding formed in a first metallic layer of the multilayer substrate, 
 a first electrically insulating layer formed above the first metallic layer, 
 a first via formed in the first electrically insulating layer, wherein the first via is configured to couple the first winding to a first connection, 
 a depression formed in the multilayer substrate, and 
 a ferromagnetic material disposed on a surface of the multilayer substrate above the first winding and in the depression, wherein the first winding is not completely encircled by the ferromagnetic material; and 
   a switch coupled to the first connection.   
     
     
         22 . The power converter of  claim 21 , wherein the ferromagnetic material is a polymer solution containing a ferromagnetic component that is deposited on the surface of the multilayer substrate and in the depression. 
     
     
         23 . The power converter of  claim 21 , wherein the magnetic circuit further comprises:
 a second insulating layer formed on the multilayer substrate below the first metallic layer;   a second winding of the magnetic device formed in a second metallic layer of the multilayer substrate, wherein the second metallic layer id formed on the multilayer substrate below the second insulating layer; and   a second via formed in the second insulating layer, wherein the second via electrically couples the second winding to the first winding.   
     
     
         24 . The power converter of  claim 21 , wherein the magnetic circuit comprises an inductor.