METHOD OF MAKING A MULTI-LAYER MAGNETO-DIELECTRIC MATERIAL
In an embodiment, a method of forming a magneto-dielectric material comprises roll coating a ferromagnetic material onto a dielectric layer comprising a dielectric material by continuously moving the dielectric layer through a ferromagnetic coating zone to form a coated sheet; forming a plurality of sheets from the coated sheet; forming a layered stack of the plurality of sheets; laminating the layered stack to form the magneto-dielectric material having a plurality of alternating ferromagnetic layers and dielectric layers. In another embodiment, a method of forming a magneto-dielectric material comprises drum roll coating a ferromagnetic material and a dielectric material onto a drum roll to form the magneto-dielectric material having a plurality of alternating ferromagnetic layers and dielectric layers.
1 . A method of forming a magneto-dielectric material, the method comprising:
roll coating a ferromagnetic material onto a dielectric layer comprising a dielectric material by continuously moving the dielectric layer through a ferromagnetic coating zone to form a coated sheet comprising a ferromagnetic layer disposed on the dielectric layer, wherein the dielectric layer travels a path from a first roll through the ferromagnetic coating zone to a second roll;
forming a plurality of sheets from the coated sheet;
forming a layered stack of the plurality of sheets;
laminating the layered stack to form the magneto-dielectric material having a plurality of alternating ferromagnetic layers and dielectric layers, wherein an uppermost layer and a lowermost layer comprise an outer layer dielectric material;
wherein the magneto-dielectric material is operable over an operating frequency range equal to or greater than a defined minimum frequency and equal to or less than a defined maximum frequency;
wherein each layer of the plurality of ferromagnetic layers has a ferromagnetic layer thickness of 1/15 th to ⅕ th the skin depth of the respective ferromagnetic layer at the defined maximum frequency;
wherein each layer of the plurality of dielectric material layers has a dielectric layer thickness and a dielectric constant that provides a dielectric withstand voltage across the respective thickness of 150 to 1,500 volts peak; and
wherein the plurality of layers has an overall thickness of less than or equal to one wavelength of the defined minimum frequency in the plurality of layers.
2 . The method of claim 1 , wherein the ferromagnetic coating zone is located on both sides of the dielectric layer.
3 . The method of claim 1 , wherein the ferromagnetic material comprises iron, nickel, cobalt, gadolinium, or a combination comprising at least one of the foregoing.
4 . The method of claim 1 , wherein the dielectric material comprises a fluoropolymer, a poly(ether ketone), a polyimide, a polyolefin, a polyester, or a combination comprising at least one of the foregoing.
5 . The method of claim 1 , wherein one or more of the ferromagnetic layer thickness is 20 nanometers to 1 micrometer, the dielectric layer thickness is 0.1 to 50 micrometers, and the magneto-dielectric material has an overall thickness of 0.1 to 3 mm
6 . The method of claim 1 , comprising laminating the magneto-dielectric material between two dielectric layers to form the uppermost layer and the lowermost layer.
7 . The method of claim 1 , further comprising coating an additional dielectric material onto the ferromagnetic layer in a dielectric coating zone located downstream of the ferromagnetic coating zone.
8 . The method of claim 7 , wherein the additional dielectric material comprises a a fluoropolymer, a poly(ether ketone), a polyimide, a polyolefin, a polyester, a ceramic, or a combination comprising at least one of the foregoing.
9 . The method of claim 1 , wherein the layered stack further comprises a plurality of thin dielectric films comprising a thin film dielectric material located between layers of the plurality of sheets.
10 . The method of claim 9 , wherein the thin film dielectric material comprises a polyester, a polyolefin, or a combination comprising at least one of the foregoing.
11 . The method of claim 1 , further comprising plasma treating the dielectric layer in a plasma zone located upstream of the ferromagnetic coating zone.
12 . A method of forming a magneto-dielectric material, the method comprising:
drum roll coating a ferromagnetic material and a dielectric material onto a drum roll, wherein a ferromagnetic coating zone and a dielectric coating zone are disposed radially in a position around the drum roll, and wherein the ferromagnetic coating zone deposits the ferromagnetic material and the dielectric coating zone deposits the dielectric material to form the magneto-dielectric material having a plurality of alternating ferromagnetic layers and dielectric layers;
wherein an uppermost layer and a lowermost layer of the magneto-dielectric material comprise an outer layer dielectric material;
wherein the magneto-dielectric material is operable over an operating frequency range equal to or greater than a defined minimum frequency and equal to or less than a defined maximum frequency;
wherein each layer of the plurality of ferromagnetic layers has a ferromagnetic layer thickness of 1/15 th to ⅕ th the skin depth of the respective ferromagnetic layer at the defined maximum frequency;
wherein each layer of the plurality of dielectric material layers has a dielectric layer thickness and a dielectric constant that provides a dielectric withstand voltage across the respective thickness of 150 to 1,500 volts peak; and
wherein the plurality of layers has an overall thickness of less than or equal to one wavelength of the defined minimum frequency in the plurality of layers.
13 . The method of claim 12 , comprising depositing an additional ferromagnetic material in an additional ferromagnetic coating zone and an additional dielectric material in an additional dielectric material coating zone; wherein a path of travel of a location on the drum roll comprises passing sequentially through the dielectric coating zone, the ferromagnetic coating zone, the additional dielectric coating zone, and the additional ferromagnetic coating zone.
14 . The method of claim 13 , wherein the ferromagnetic material and the additional ferromagnetic material are the same.
15 . The method of claim 13 , wherein the dielectric material and the additional dielectric material are different.
16 . The method of claim 13 , wherein the additional dielectric material comprises a curable composition or a ceramic.
17 . The method of claim 12 , further comprising first coating the drum roll with only the dielectric material, starting the deposition of the ferromagnetic layer, after a desired number of layers has been deposited, stopping the deposition of the ferromagnetic layer, and then stopping the deposition of the dielectric material.
18 . The method of claim 12 , wherein the ferromagnetic material comprises iron, nickel, cobalt, gadolinium, or a combination comprising at least one of the foregoing.
19 . The method of claim 12 , wherein the dielectric material comprises a fluoropolymer, a poly(ether ketone), a polyimide, a polyolefin, a polyester, or a combination comprising at least one of the foregoing.
20 . The method of claim 12 , further comprising plasma treating the dielectric layer in a plasma zone located upstream of the ferromagnetic coating zone.