Noise suppressing assemblies
Assemblies having multi-functionalities of any combination of heat spreading, absorption of stray radiation, signal focusing, and shielding are provided. The assemblies may include a heat spreading layer of at least one sheet of a compressed particles of exfoliated graphite, graphitized polymers and combinations thereof. The assemblies may also include at least one magnetic layer, which may provide the benefits of magnetic flux management and/or stray radiation absorption. The assemblies may include an optional plastic coating on one or both of the exterior surfaces. The assemblies may be used to enable fast wireless charging of electronic devices by efficiently focusing magnetic flux for better power transmission efficiency.
1. An assembly comprising:
a graphite substrate comprising one or more sheets of at least one of compressed particles of exfoliated graphite, a graphitized polymer and combinations thereof, the graphite substrate having a coated region located on at least one side of the graphite substrate, the coated region including a magnetic coating disposed on a surface of the graphite substrate, the magnetic coating having a thickness of more than 40 microns and no more than 300 microns;
an induction coil for wireless charging having an inwardly facing surface disposed adjacent the magnetic coating, the induction coil being capable of receiving a signal having a frequency of at least 80 kHz up to 8 GHz; and
a battery located on the side of the graphite substrate opposite the induction coil,
wherein the coated region is adapted to direct magnetic flux of the signal to the induction coil while the graphite substrate is adapted to shield the battery from the magnetic flux.
2. The assembly of claim 1 further comprising a protective coating disposed adjacent the magnetic coating on a side of the magnetic coating opposite the graphite substrate.
3. The assembly of claim 1 wherein the magnetic coating includes more than one layer.
4. The assembly of claim 1 wherein the graphite substrate is comprised of a sheet of compressed particles of exfoliated graphite, the sheet having a thickness of at least 40 microns, wherein the sheet has a major surface having a surface area greater than a surface area of the induction coil.
5. The assembly of claim 1 wherein the magnetic coating comprises at least two (2) layers, the first layer comprising a mixture of 25-75% by weight of magnetic shielding composition and 75-25% by weight of an absorbing compound.
6. The assembly of claim 5 wherein the first layer includes 40-60% by weight of the magnetic shielding composition and 60-40% by weight of the absorbing compound.
7. The assembly of claim 1 wherein the coating comprises no more than sixty percent by weight (60% pbw) of iron.
8. The assembly of claim 1 wherein the graphite substrate comprises less than five percent by mass of a binder.
9. The assembly of claim 8 wherein the binder is one of an elastomer and a resin.
10. The assembly of claim 1 wherein the graphite substrate is comprised of a sheet of graphitized polymers, the sheet having a thickness of at least 20 microns and an in-plane thermal conductivity of at least 300 W/mK.