Magnetic isolator, method of making the same, and device containing the same

Patent metadata

Field	Value
Publication number	US-10734725-B2
Application number	US-201615780682-A
Country	US
Kind code	B2
Filing date	Nov 22, 2016
Priority date	Dec 8, 2015
Publication date	Aug 4, 2020
Grant date	Aug 4, 2020

Abstract

A magnetic isolator includes a dielectric film having a layer of electrically-conductive soft magnetic material bonded thereto. The layer of electrically-conductive soft magnetic material comprises substantially coplanar electrically-conductive soft magnetic islands separated one from another by gaps. At least some of the electrically-conductive soft magnetic islands have an outer insulating oxidized layer that electrically insulates them from adjacent electrically-conductive soft magnetic islands. The gaps at least partially suppress electrical eddy current induced within the layer of soft magnetic material when in the presence of applied external magnetic field. An electronic device including the magnetic isolator and a method of making the magnetic isolator are also disclosed.

First claim

What is claimed is:

1. A magnetic isolator comprising a substrate having a layer of electrically-conductive soft magnetic material bonded thereto, wherein the layer of electrically-conductive soft magnetic material comprises electrically-conductive soft magnetic islands separated one from another by gaps, wherein at least some of the electrically-conductive soft magnetic islands have an outer insulating oxidized layer that electrically insulates them from adjacent electrically-conductive soft magnetic islands, and wherein the gaps at least partially suppress electrical eddy current induced within the layer of electrically-conductive soft magnetic material by an external magnetic field.

2. The magnetic isolator of claim 1 , wherein the electrically-conductive soft magnetic islands comprise nanocrystalline ferrous material.

3. The magnetic isolator of claim 1 , wherein the outer insulating oxidized layer comprises an inorganic oxide layer containing iron.

4. The magnetic isolator of claim 1 , wherein a ratio of an average depth of the interconnected gaps to an average thickness of the electrically-conductive soft magnetic islands is at least 0.5.

5. The magnetic isolator of claim 1 , wherein the electrically-conductive soft magnetic islands are randomly sized and shaped.

6. The magnetic isolator of claim 1 , wherein the network of interconnected gaps is coextensive with the layer of electrically-conductive soft magnetic material along its length and width.

7. An electronic device adapted to inductively couple with a remotely generated magnetic field, the electronic device comprising:
a substrate;
an antenna bonded to the substrate;
an integrated circuit disposed on the substrate and electrically coupled to the antenna; and
a magnetic isolator according to claim 1 disposed between the antenna and the substrate.

8. The electronic device of claim 7 , wherein the antenna comprises a loop antenna.

9. A method of making a magnetic isolator, the method comprising steps:
a) providing a substrate having a layer of electrically-conductive soft magnetic material bonded thereto;
b) forming gaps in the layer of electrically-conductive soft magnetic material defining electrically-conductive soft magnetic islands; and
c) forming an outer insulating oxidized layer on at least some of the electrically-conductive soft magnetic islands sufficient to electrically insulate them from adjacent electrically-conductive soft magnetic islands, wherein the gaps at least partially suppress eddy current induced within the layer of electrically-conductive soft magnetic material by an external magnetic field.

10. The method of claim 9 , wherein step c) comprises contacting the electrically-conductive soft magnetic islands formed in step b) with an oxidizing agent.

11. The method of claim 9 , wherein the electrically-conductive soft magnetic islands comprise nanocrystalline ferrous material.

12. The method of claim 9 , wherein the outer insulating oxidized layer comprises an inorganic oxide layer containing iron.

13. The method of claim 9 , wherein the network of interconnected gaps is coextensive with the layer of electrically-conductive soft magnetic material along its length and width.

14. The method of claim 9 , wherein in step b), the network of interconnected gaps is provided at least partially by intentionally mechanically cracking the layer of electrically-conductive soft magnetic material.

15. The method of claim 9 , wherein step and b) comprises stretching the substrate by at least 20 percent in at least one dimension.

Assignees

• 3M Innovative Properties Co

Inventors

• Graff Michael S
• Roy Biplab K

Classifications

• H01F27/361

  made of combinations of electrically conductive material and ferromagnetic material · CPC title

• H01F27/36

  Electric or magnetic shields or screens (movable for varying inductance H01F21/10) · CPC title

• H01Q7/06 Primary

  with core of ferromagnetic material (H01Q7/02 takes precedence) · CPC title

• H01Q17/00

  Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems · CPC title

• H01F1/15333

  containing nanocrystallites, e.g. obtained by annealing · CPC title