ELECTROMAGNETIC WAVE ABSORBING SHEET

Abstract

An electromagnetic wave absorbing sheet includes a metallic base and an electromagnetic wave absorption film formed on the metallic base. The electromagnetic wave absorption film contains MTC-substituted ε—Fe2O3, black titanium oxide, a conductive filler, and a resin. The MTC-substituted ε—Fe2O3 is a crystal belonging to the same space group as an ε—Fe2O3 crystal and containing Ti, Co, Fe, and at least one element selected from the group consisting of Ga, In, Al, and Rh. The proportion of the conductive filler to the electromagnetic wave absorption film is equal to or greater than 0.1% by volume and equal to or less than 10% by volume.

Description

Claims

1. An electromagnetic wave absorbing sheet comprising a metallic base, andan electromagnetic wave absorption film formed on the metallic base,the electromagnetic wave absorption film containing MTC-substituted ε—Fe2O3,black titanium oxide,a conductive filler, anda resin,the MTC-substituted ε—Fe2O3 being a crystal belonging to the same space group as an ε—Fe2O3 crystal and containing Ti, Co, Fe, and at least one element selected from the group consisting of Ga, In, Al, and Rh,proportion of the conductive filler to the electromagnetic wave absorption film being equal to or greater than 0.1% by volume and equal to or less than 10% by volume.

2. The electromagnetic wave absorbing sheet of claim 1, wherein the electromagnetic wave absorbing sheet has a range in which an electromagnetic wave incident angle causing a return loss equal to or greater than 15 dB is equal to or greater than 0 degrees and equal to or less than 20 degrees over a frequency range from 76 GHz to 81 GHz.

3. The electromagnetic wave absorbing sheet of claim 1, wherein the electromagnetic wave absorption film has a thickness equal to or greater than 0.1 mm and equal to or less than 0.5 mm.

4. The electromagnetic wave absorbing sheet of claim 1, wherein the MTC-substituted ε—Fe2O3 is expressed by ε-MxTiyCoyFe2-2y-xO3 where M is at least one element selected from the group consisting of Ga, In, Al, and Rh, 0 < x < 1, 0 < y < 1, and x + 2y < 2.

5. The electromagnetic wave absorbing sheet of claim 1, wherein the black titanium oxide includes at least one compound selected from the group consisting of Ti4O7 and λ—Ti3O5.

6. The electromagnetic wave absorbing sheet of claim 1, wherein the resin includes at least one resin selected from the group consisting of silicone resins, acrylic resins, and epoxy resins.

7. An electromagnetic wave absorbing sheet comprising a metallic base, andan electromagnetic wave absorption film formed on the metallic base,the electromagnetic wave absorption film containing MTC-substituted ε—Fe2O3,black titanium oxide, anda resin,the MTC-substituted ε—Fe2O3 being a crystal belonging to the same space group as an e-Fe2O3 crystal and containing Ti, Co, Fe, and at least one element selected from the group consisting of Ga, In, Al, and Rh,an imaginary part of a relative dielectric constant of the black titanium oxide being equal to or greater than 2.0 when the black titanium oxide accounts for 30% by volume of the resin.

8. The electromagnetic wave absorbing sheet of claim 7, wherein the electromagnetic wave absorbing sheet has a range in which an electromagnetic wave incident angle causing a return loss equal to or greater than 15 dB is equal to or greater than 0 degrees and equal to or less than 20 degrees over a frequency range from 76 GHz to 81 GHz.

9. The electromagnetic wave absorbing sheet of claim 7, wherein the electromagnetic wave absorption film has a thickness equal to or greater than 0.1 mm and equal to or less than 0.5 mm.

10. The electromagnetic wave absorbing sheet of claim 7, wherein the MTC-substituted ε—Fe2O3 is expressed by ε-MxTiyCoyFe2-2y-xO3 where M is at least one element selected from the group consisting of Ga, In, Al, and Rh, 0 < x < 1, 0 < y < 1, and x + 2y < 2.

11. The electromagnetic wave absorbing sheet of claim 7, wherein the black titanium oxide includes at least one compound selected from the group consisting of Ti4O7 and λ—Ti3O5.

12. The electromagnetic wave absorbing sheet of claim 7, wherein the resin includes at least one resin selected from the group consisting of silicone resins, acrylic resins, and epoxy resins.