Magnetic field shielding sheet and wireless power transmitting module including same
A magnetic field shielding sheet and a wireless power transfer module that includes the same are provided. The magnetic field shielding sheet, according to an exemplary embodiment of the present invention, which is applied to a combo-type antenna unit that includes at least two antennas using different frequency bands of magnetic fields, comprises: a first sheet layer that includes a metal component that shields a first frequency band of a magnetic field and concentrates the magnetic field in a designated direction; a second sheet layer that shields a second frequency band of a magnetic field and concentrates the magnetic field in a designated direction; and a micro-piece separation and oxidation preventing member provided on a side surface of the first sheet layer in order to prevent a micro-piece from being separated from the side surface of the first sheet or to prevent the side surface from being oxidized. According to the present invention, by virtue of the micro-piece separation and oxidation preventing member provided on the side surface of the first sheet layer, it is possible to prevent the side surface from being oxidized and to prevent short-circuiting due to particles.
1. A magnetic field shielding sheet, which is applied to a combo-type antenna unit including at least two antennas using magnetic fields of different frequency bands, the magnetic field shielding sheet comprising:
a first sheet layer configured to shield a magnetic field of a first frequency band and concentrate the magnetic field in a designated direction and including a metal component;
a second sheet layer configured to shield a magnetic field of a second frequency band and concentrate the magnetic field in a designated direction; and
a micro-piece separation and oxidation preventing member provided on a side surface of the first sheet layer, which is an exposed surface, to prevent separation of a micro-piece from the side surface of the first sheet layer or prevent oxidation of the side surface, wherein the side surface of the first sheet layer is a stamped surface.
2. The magnetic field shielding sheet of claim 1 , wherein the micro-piece separation and oxidation preventing member is a protective film.
3. The magnetic field shielding sheet of claim 1 , wherein the first sheet layer is provided to have the same size as the second sheet layer.
4. The magnetic field shielding sheet of claim 3 , wherein the micro-piece separation and oxidation preventing member includes a first portion which covers an upper surface of the first sheet layer and a second portion which extends from the first portion to cover the side surface of the first sheet layer.
5. The magnetic field shielding sheet of claim 4 , wherein the second portion extends to cover a side surface of the second sheet layer.
6. The magnetic field shielding sheet of claim 1 , wherein the first sheet layer is provided to have a smaller size than the second sheet layer.
7. The magnetic field shielding sheet of claim 6 , wherein the micro-piece separation and oxidation preventing member includes a first portion which covers an upper surface of the first sheet layer, a second portion which extends from the first portion to cover the side surface of the first sheet layer, and a third portion which extends from the second portion to cover a portion of the second sheet layer.
8. The magnetic field shielding sheet of claim 6 , wherein a buffer layer is provided on an upper surface of the second sheet layer and disposed at a periphery of the first sheet layer to surround the first sheet layer, and the second sheet layer is provided to have a size equal to a sum of sizes of the first sheet layer and the buffer layer.
9. The magnetic field shielding sheet of claim 6 , wherein the magnetic field of the first frequency band is for wireless power transfer, the magnetic field of the second frequency band is for near field communication, the first sheet layer is disposed to correspond to a wireless power transfer antenna, and the second sheet layer is disposed to correspond to a near field communication antenna.
10. The magnetic field shielding sheet of claim 1 , wherein the first sheet layer and the second sheet layer are made of magnetic materials having different magnetic permeabilities.
11. The magnetic field shielding sheet of claim 1 , wherein the first sheet layer is a ribbon sheet including at least one of an amorphous alloy and a nanocrystalline alloy, and the second sheet layer is a ferrite sheet or a polymer sheet.
12. The magnetic field shielding sheet of claim 11 , wherein the ferrite sheet is made of a Mn—Zn ferrite or a Ni—Zn ferrite.
13. The magnetic field shielding sheet of claim 1 , wherein the first sheet layer is formed by stacking ribbon sheets including at least one of an amorphous alloy and a nanocrystalline alloy in multiple layers.
14. The magnetic field shielding sheet of claim 1 , wherein at least one or both of the first sheet layer and the second sheet layer are divided into a plurality of micro-pieces.
15. The magnetic field shielding sheet of claim 1 , wherein the micro-piece separation and oxidation preventing member is attached via an adhesive including a non-conductive component.
16. A wireless power transfer module comprising:
an antenna unit including a wireless power transfer antenna and a near field communication antenna; and
the magnetic field shielding sheet according to claim 1 , which is disposed on one surface of the antenna unit, shields a magnetic field generated by the antenna unit, and concentrates the magnetic field in a designated direction.
17. The wireless power transfer module of claim 16 , wherein the antenna unit further includes a magnetic secure transmission (MST) antenna.
18. The wireless power transfer module of claim 16 , wherein a total thickness of the wireless power transfer module ranges from 0.15 to 0.6 mm.
19. The wireless power transfer module of claim 18 , wherein the total thickness of the wireless power transfer module is 0.3 mm.
20. A portable terminal comprising the wireless power transfer module according to claim 16 .