Method of making a multilayer monolithic magnetic component

• US 5,479,695 A
• Filed: 07/01/1994
• Issued: 01/02/1996
• Est. Priority Date: 05/02/1991
• Status: Expired due to Term

• Current Assignee: AT&T IPM Corp. (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Johnson, David W. Jr., Roy, Apurba, Thomson, John Jr., Grader, Gideon S.
• Primary Examiner(s): Hall, Carl E.
• Application Number:
  US08/270,197
• Time in Patent Office: 550 Days
• Field of Search: 29/602.1, 29/605, 29/606, 336/200, 336/233, 264/58, 264/61
• US Class Current: 29/602.1
• CPC Class Codes: H01F 17/0033 with the coil helically wound around a magnetic core
• CPC Class Codes: H01F 41/16 the magnetic material being applied in the form of particles, e.g. by serigraphy , to form thick magnetic films or precursors therefor H01F41/18 -H01F41/24 take precedence
• CPC Class Codes: Y10T 29/4902 Electromagnet, transformer or inductor

Abstract

Magnetic components are fabricated as monolithic structures using multilayer co-fired ceramic tape techniques. Fabrication of these magnetic components involves constructing multiple layers of a magnetic material and an insulating non-magnetic material to form a monolithic structure with well defined magnetic and insulating non-magnetic regions. Windings are formed using screen printed conductors connected through the multilayer structure by conducting vias.

Claims

1. A method for constructing a solid composite magnetic component comprising the steps of:

preparing a magnetic material in a ceramic material format having a first sintering rate and a first sintering temperature;

preparing an insulating non-magnetic material in a ceramic material format, with a sintering rate and sintering temperature substantially identical to the first sintering rate and first sintering temperature;

preparing apertures in the insulating non-magnetic material for accepting the magnetic material;

depositing conductors within the insulating non-magnetic material which are connected to form at least a winding to provide electromagnetic excitation of the magnetic material;

forming a composite structure of the magnetic material and the insulating non-magnetic material by adding the magnetic material to the apertures to form a structure with well defined magnetic and insulating non-magnetic regions; and

co-firing the structure to form a solid composite structure.

2. A method for constructing a solid composite magnetic component as claimed in claim 4, and wherein the step of:

forming a composite structure includes providing top and bottom layers of insulating non-magnetic material to form a top and bottom structure of the component.

3. A method for constructing a solid composite magnetic component as claimed in claim 1, and further comprising the steps of:

preparing the magnetic material in a ceramic paste format;

preparing the insulating non-magnetic material in a ceramic tape format;

the step of forming the structure includes the step of layering the insulating non-magnetic material tape; and

applying pressure to laminate the structure prior to the step of co-firing.

4. A method for constructing a solid composite magnetic component as claimed in claim 1, and further comprising the steps of:

preparing the magnetic material in a ceramic tape and a ceramic paste format;

preparing the insulating non-magnetic material in a ceramic tape format;

the step of forming the structure includes the step of layering the magnetic and insulating non-magnetic material; and

applying pressure to laminate the structure prior to the step of co-firing.

5. A method for constructing a solid composite magnetic component comprising the steps of:

preparing a magnetic material in a ceramic material format having a first sintering rate and a first sintering temperature;

preparing an insulating non-magnetic material in a ceramic tape format with a sintering rate and sintering temperature substantially identical to the first sintering rate and first sintering temperature;

including apertures in the insulating non-magnetic material for accepting the magnetic material;

forming a structure by successive layering of the insulating non-magnetic material and adding the magnetic material to the apertures to form a first structure with well defined magnetic and insulating non-magnetic regions;

depositing conducting paths on selected layers of the insulating nonmagnetic material and joining the conducting paths to form windings encircling selected portions of the apertures containing the magnetic material;

applying pressure to laminate the first structure; and

co-firing the first structure to form a solid composite structure.

6. A method for constructing a composite magnetic component as defined in claim 5;

wherein the step of preparing an insulating non-magnetic material includes the step of doping the insulating non-magnetic material with a metallic oxide material to cause it to have a sintering rate and sintering temperature substantially identical to the first sintering rate and first sintering temperature.

7. A method for constructing a composite magnetic component as defined in claim 5;

wherein the step of preparing a magnetic material includes the step of doping the magnetic material with a metallic oxide material to cause it to have a sintering rate and sintering temperature substantially identical to the sintering rate and sintering temperature of the insulating non-magnetic material.

8. A method for constructing a magnetic component as claimed in claim 5, wherein:

the magnetic and insulating non-magnetic material includes a spinel ferrite of the form M_1+x Fe_2-y O_4-z.

9. A method for constructing a solid composite magnetic component as claimed in claim 5;

wherein the step of preparing the magnetic material includes preparing it in a ceramic paste format.

10. A method for constructing a solid composite magnetic component as claimed in claim 5;

wherein the step of preparing the magnetic material includes preparing it in a ceramic tape format.

11. A method for constructing a composite magnetic component as claimed in claim 5;

wherein the step of co-firing includes the step of co-firing to a temperature of 800°

to 1400°

C.

12. A method for constructing a composite magnetic component as defined in claim 5 and further comprising the steps of:

doping the insulating non-magnetic material with a metallic oxide material to increase its resistivity and decrease its permeability.

13. A method for constructing a composite magnetic component as defined in claim 5 and further comprising the steps of:

constructing the conducting paths with a conductive material containing Pd which conforms to the firing and sintering characteristics of the magnetic material and the insulating non-magnetic material.

14. A method for constructing a composite magnetic component as defined in claim 5 and further comprising the steps of:

constructing the conducting paths with a conductive material containing a Pd-Ag alloy which conforms to the firing and sintering characteristics of the magnetic material and the insulating non-magnetic material.

15. A method for constructing a composite magnetic component as defined in claim 5 and further comprising the steps of:

constructing the conducting paths with a conductive material containing metallic particles and which conforms to the firing and sintering characteristics of the magnetic material and the insulating non-magnetic material.

16. A method for constructing a composite magnetic component as defined in claim 8 wherein:

the values of x, y and z may assume positive and negative numerical values.

17. A method for constructing a composite magnetic component as defined in claim 8;

wherein the M material includes at least one of the elements Mn, Mg, Ni, Zn, Fe, Cu, Co, Zr, Va, Cd, Ti, Cr and Si.

18. A method for constructing a composite magnetic component as defined in claim 5 wherein the insulating non-magnetic material is a Ni-ferrite material.

19. A method for constructing a composite magnetic component as defined in claim 5:

wherein the insulating non-magnetic material is a Zn-ferrite material.

20. A method for constructing a composite magnetic component is claim 5:

wherein the insulating non-magnetic material is a Mg-ferrite material.

21. A method for constructing a composite magnetic component as defined in claim 5:

wherein the magnetic material is a MnZn material.

22. A method for constructing a composite magnetic component as defined in claim 5:

wherein the magnetic material is a NiZn material.

23. A process for producing a solid composite magnetic component comprising at least two different materials each comprised of a ferrite matrix;

wherein the ferrite materials are of the form M_1+x Fe_2-y O_4-z

comprising the steps of;

preparing a magnetic material by;

providing a first ferrite powder of a substantially MnZn ferrite composition suitable to provide a relatively high permeability in a resulting first ferrite matrix,

preparing an insulating non-magnetic material by;

providing a second ferrite powder of a substantially Ni ferrite composition suitable to provide a high resistivity and a low permeability in a resulting second ferrite matrix, adding a Cu oxide to the second ferrite powder in an amount ranging from 1% mol to 10% mol of the total amount of the second ferrite powder so that the second ferrite powder has a sintering rate and sintering temperature substantially identical to that of the first ferrite powder,

admixing the second ferrite powder with an organic binding material and forming the resulting mixture into a ceramic tape,

defining different tape layers with specified layers having certain defined apertures;

forming a layered structure with the different tape layers in which the apertures form a geometric structure suitable for a magnetic core and in which the apertures are filled with a material comprising the first ferrite powder,

laminating the layered structure by applying a pressure thereto,

firing the laminated structure;

sintering the resulting structure at a temperature exceeding 800°

centigrade to produce a sintered product having two ferrite matrix materials in a single composite structure;

cooling the single composite structure to form the solid composite magnetic component.

24. A process for producing a solid composite magnetic component as claimed in claim 23:

wherein the step of preparing an insulating non-magnetic material includes adding a Zr oxide to the second ferrite powder to increase its resistivity and further reduce its permeability.

25. A process for producing a solid composite magnetic component as claimed in claim 23:

wherein the step of preparing an insulating non-magnetic material includes adding a Zr oxide to the second ferrite powder to increase its resistivity and further reduce is permeability.

26. A process for producing a solid composite magnetic component as defined in claim 23,

wherein the step of preparing a magnetic material includes admixing the first ferrite powder with an organic binder and forming the resulting mixture into a second ceramic tape.

27. A method for constructing a solid composite magnetic component with multilayer ceramic tape layers;

comprising the steps of;

providing a first ferrite powder of MnZn ferrite composition having a specific sintering rate and temperature;

providing a second ferrite powder of a Ni ferrite composition and further doped with copper oxide particles in an amount equaling 1-10% of the overall molar composition to introduce a liquid phase into the second ferrite material to lower its sintering temperature and modify its sintering rate so that they equal the specific sintering rate and temperature;

preparing a magnetic material comprising a binder and the first ferrite powder of a MnZn ferrite composition;

preparing an insulating non-magnetic material in the form of a ceramic tape comprising a binder and the second ferrite power of a Ni ferrite composition;

forming apertures in the insulating non-magnetic material for accepting the magnetic material;

placing pluralities of the insulating non-magnetic materials formed of ceramic tape adjacent each other at least in part in layers and inserting the magnetic material in the apertures to assemble a multilayer structure having well defined regions of high permeability and well defined regions of low permeability adjacent the regions of high permeability; and

applying pressure to laminate the multilayer structure;

co-firing the laminated structure to a temperature within a range of 800 to 1400 degrees Centigrade to join the layers into a solid composite structure.

28. A method for constructing a solid composite magnetic component with multilayer ceramic tape layers as claimed in claim 27;

wherein the step of co-firing is performed within a range of 1250 to 1350 degrees centigrade.

29. A method for constructing a solid composite magnetic component with multilayer ceramic tape layers as claimed in claim 27;

and including the step of;

doping the second ferrite powder of a Ni ferrite composition with MnO to lower its permeability and conductivity.

30. A method for constructing a solid composite magnetic component with multilayer ceramic tape layers as claimed in claim 27;

and including the step of;

doping the second ferrite powder of a Ni ferrite composition with ZrO₂ to lower its permeability and conductivity.

31. A method for constructing a solid composite structure including at least a magnetic component comprising the steps of:

preparing a magnetic ceramic material having a first sintering rate and a first sintering temperature;

preparing an insulating non-magnetic material in a ceramic tape format, with a sintering rate and sintering temperature substantially identical to the first sintering rate and first sintering temperature;

forming a structure by successive layering of the insulating non-magnetic material and combining it with the magnetic material to form a first structure with well defined magnetic and non-magnetic regions;

printing conductors on a portion of the structure so as to magnetically engage the magnetic material;

applying pressure to laminate the structure; and

co-firing the first structure to form a solid composite structure.

32. A method for constructing a solid composite structure as claimed in claim 31, and further comprising the steps of:

preparing apertures in the ceramic tape of insulating non-magnetic material for accepting the magnetic material; and

printing the conductors on selected layers of the ceramic tape of insulating non-magnetic material and constructing conducting vias to interconnect conductors printed on different layers.

33. A method for constructing a solid composite structure as claimed in claim 32, and further comprising the steps of:

preparing the magnetic ceramic material in a ceramic tape format.