Magnetic sheet, coil module having magnetic sheet, and non-contact power supply device

Patent metadata

Field	Value
Publication number	US-11749432-B2
Application number	US-202016953689-A
Country	US
Kind code	B2
Filing date	Nov 20, 2020
Priority date	Dec 11, 2019
Publication date	Sep 5, 2023
Grant date	Sep 5, 2023

Abstract

A magnetic sheet according to the present invention contains Mn—Zn ferrite as a main component and is comprising of a sheet-shaped sintered body. In this magnetic sheet, a difference |σs−σc| between a residual stress σs in a surface layer portion and a residual stress σc in a central portion at a cross section is 20 MPa or less in absolute value.

First claim

What is claimed is:

1. A magnetic sheet comprising a sheet-shaped sintered body with an average thickness of 2500 μm or less,
wherein the sheet-shaped sintered body contains Mn—Zn ferrite as a main component,
a surface-side portion is defined as an area from an outermost surface of the sheet-shaped sintered body to a predetermined depth in a cross section of the sheet-shaped sintered body, in which the predetermined depth is 10 μm or more and 50 μm or less,
a central portion is defined as a center in the thickness direction at the cross section of the sheet-shaped sintered body, and
a difference between a residual stress in the surface-side portion and a residual stress in the central portion at the cross section of the sheet-shaped sintered body is 20 MPa or less in absolute value.

2. The magnetic sheet according to claim 1 , wherein the difference between the residual stress in the surface-side portion and the residual stress in the central portion at the cross section of the sheet-shaped sintered body is 10 MPa or less in absolute value.

3. The magnetic sheet according to claim 1 , wherein the residual stress in the surface-side portion and the residual stress in the central portion are both compressive stresses at the cross section of the sheet-shaped sintered body.

4. A coil module comprising the magnetic sheet according to claim 1 .

5. A non-contact power supply device comprising the coil module according to claim 4 .

6. The magnetic sheet according to claim 1 , wherein the Mn—Zn ferrite includes iron oxide in an amount of 51 mol % or more and 58 mol % or less in terms of Fe 2 O 3 , zinc oxide in an amount of 3 mol % or more and 18 mol % or less in terms of ZnO, and the balance comprising manganese oxide.

7. The magnetic sheet according to claim 1 , wherein the average thickness is 50 μm to 2500 μm.

8. The magnetic sheet according to claim 1 , wherein the average thickness is 100 μm to 2000 μm.

9. The magnetic sheet according to claim 1 , wherein the average thickness is 100 μm to 1000 μm.

10. The magnetic sheet according to claim 1 , wherein the sheet-shaped sintered body has an initial permeability pi of 1800 or more.

11. The magnetic sheet according to claim 1 , wherein the sheet-shaped sintered body has an initial permeability pi of 2000 or more.

12. The magnetic sheet according to claim 1 , wherein the sheet-shaped sintered body has an initial permeability pi of 2200 or more.

13. The magnetic sheet according to claim 1 , wherein the sheet-shaped sintered body has a magnetic loss of 1000 kW/m 3 or less.

14. The magnetic sheet according to claim 1 , wherein the sheet-shaped sintered body has a magnetic loss of 800 kW/m 3 or less.

15. The magnetic sheet according to claim 1 , wherein the sheet-shaped sintered body has a magnetic loss of 600 kW/m 3 or less.

Assignees

• Tdk Corp

Inventors

• Kubo Yoshihiro
• Oka Yoshito

Classifications

• H01F1/344 Primary

  Ferrites, e.g. having a cubic spinel structure (X2+O)(Y23+O3), e.g. magnetite Fe3O4 · CPC title

• H01F1/16

  in the form of sheets (H01F1/147 takes precedence) · CPC title

• H01F27/366

  made of ferromagnetic material · CPC title

• H02J50/70 Primary

  involving the reduction of electric, magnetic or electromagnetic leakage fields · CPC title

• H01F38/14

  Inductive couplings {(for wireless supply or distribution of electric power using inductive coupling H02J50/10)} · CPC title