HEATING ELEMENTS AND HEATING DEVICES
In a first aspect, a heating element includes a network of electrically conductive layers comprising a plurality of polymeric resistive layers and two or more electrodes in contact with the network of electrically conductive layers. The polymeric resistive layers have a sheet resistance in a range of from about 0.5 ohm/square to about 2 Megaohm/square. The array of electrodes electrically connects the heating element to a power source. In a second aspect, a forced-convection heating device comprising the heating element of the first aspect.
1 . A heating element comprising:
a network of electrically conductive layers comprising a plurality of polymeric resistive layers, wherein the polymeric resistive layers have a sheet resistance in a range of from about 0.5 ohm/square to about 2 Megaohm/square; and
two or more electrodes in contact with the network of electrically conductive layers, wherein the array of electrodes electrically connects the heating element to a power source.
2 . The heating element of claim 1 , wherein the polymeric resistive layers comprise a first polymeric dielectric material.
3 . The heating element of claim 2 , wherein the first polymeric dielectric material comprises a polyimide.
4 . The heating element of claim 1 , wherein the first polymeric resistive layers further comprise electrically conductive filler.
5 . The heating element of claim 1 , wherein the electrically conductive layers further comprise a plurality of polymeric dielectric layers in contact with the plurality of polymeric resistive layers.
6 . The heating element of claim 5 , wherein the polymeric dielectric layers comprise a second polymeric dielectric material.
7 . The heating element of claim 6 , wherein the second polymeric dielectric material comprises a polyimide.
8 . The heating element of claim 1 , wherein the two or more electrodes comprise an electrically conductive paste or a metal.
9 . The heating element of claim 1 , wherein the network is an open cellular network.
10 . The heating element of claim 9 , wherein the open cellular network comprises a honeycomb cellular geometry.
11 . The heating element of claim 1 , wherein the electrically conductive layers further comprise one or more vias.
12 . The heating element of claim 1 , wherein the electrically conductive layers further comprise one or more outer dielectric layers.
13 . The heating element of claim 1 , further comprising an encapsulant.
14 . The heating element of claim 1 , further comprising a frame or mechanical support structure.
15 . A forced-convection heating device comprising the heating element of claim 1 .
16 . The forced-convection heating device of claim 15 , further comprising one or more bus bars electrically connected to the heating element.