Porous Media Evaporator

Abstract

A method and apparatus are provided for an evaporator assembly. The evaporator assembly includes an evaporator body, a coating vessel, and a porous medium. The evaporator body includes an evaporator sidewall, an evaporator volume defined by the evaporator sidewall, and an opening defined by the evaporator sidewall. The coating material vessel includes a vessel sidewall, a coating material volume defined by the vessel sidewall, and a coating material vessel disposed within the coating material volume. The porous medium is disposed partially within the coating material vessel and partially within the evaporator volume.

Description

[Technical Field]

[0001] This disclosure relates generally to evaporation systems. More particularly, this disclosure relates generally to thermal evaporator designs that provide uniform evaporation rates at relatively low temperatures. [Background technology]

[0002] The processing of flexible substrates, such as plastic films or foils, is in high demand in the packaging, semiconductor, and other industries. Processing can involve coating flexible substrates with selected materials, such as metals. Economical production of these coatings is limited by the required thickness uniformity of the product, the reactivity of the coating material, the cost of the coating material, and the deposition rate of the coating material. The most challenging applications generally involve deposition in a vacuum chamber for precise control of coating thickness and optimal optical properties. Due to the high capital cost of vacuum coating equipment, large-scale commercial applications require high throughput of the coated area. The coated area per unit time is typically proportional to the width of the substrate being coated and the vacuum deposition rate of the coating material.

[0003] Deposition processes that can utilize large vacuum chambers have significant economic advantages. Vacuum coating chambers, substrate processing and handling equipment, and pumping capacity do not increase in cost proportionally with chamber size. Therefore, the most economical process for a given deposition rate and coating design will utilize the largest substrate available. Large substrates can generally be processed into separate parts after the coating process is complete. For products made from a continuous web, the web is slit or cut into sheets, either to the dimensions of the final product or to narrow webs appropriate for subsequent manufacturing operations.

[0004] One technique used for deposition is thermal evaporation. Thermal evaporation occurs when a source material is heated in an open crucible in a vacuum chamber to a temperature such that there is sufficient source vapor flow to condense on the cooler substrate. The source material can be heated indirectly by heating the crucible, or directly by a high-current electron beam directed at the source material confined in the crucible. Thermal evaporation typically occurs at high temperatures, which can result in high heat loads on the substrate being processed. These high heat loads can damage the substrate. One method for reducing the heat load involves cooling the crucible by radiative cooling. However, radiative cooling is typically very slow and can result in long chamber downtimes and increased cost of ownership.

[0005] Additionally, current thermal evaporator designs that use external heaters can suffer from radiative heat losses, which can lead to increased power consumption to achieve the target temperature.

[0006] Therefore, there is a need for an apparatus and method for reducing the heat load on a substrate in a thermal evaporation process. Summary of the Invention

[0007] This disclosure relates generally to evaporation systems for supplying gases for reactive deposition processes. More particularly, this disclosure relates generally to thermal evaporator designs that provide uniform evaporation rates at relatively low temperatures.

[0008] In one aspect, an evaporator assembly is provided. The evaporator assembly includes an evaporator body, a coating vessel, and a porous medium. The evaporator body includes an evaporator sidewall, an evaporator volume defined by the evaporator sidewall, and an opening defined by the evaporator sidewall. The coating material vessel includes a vessel sidewall, a coating material volume defined by the vessel sidewall, and a coating material vessel disposed within the coating material volume. The porous medium is disposed partially within the coating material vessel and partially within the evaporator volume.

[0009] In another aspect, an evaporation system is provided. The evaporation system includes one or more evaporation assemblies. Each of the one or more evaporation assemblies includes an evaporator body, a coating material container, and a porous medium. The evaporation body includes an evaporator sidewall, an evaporator volume defined by the evaporator sidewall, and an opening defined by the evaporator sidewall. The coating material container includes a container sidewall, a coating material volume defined by the container sidewall, and a coating material tank disposed within the coating material volume. The porous medium is disposed partially within the coating material tank and partially within the evaporator volume.

[0010] In another aspect, a method of coating a substrate is provided that includes providing the substrate to an evaporation system, feeding a coating material to an evaporator, heating a porous medium in the evaporator, absorbing the coating material into the porous medium, evaporating the coating material to form a coating material vapor, and coating the substrate with the coating material vapor.

[0011] In order that the features referred to in the present disclosure may be understood in detail, the above briefly summarized aspects can be further elucidated by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings illustrate only typical embodiments of the present disclosure and therefore should not be considered as limiting its scope, as other equally effective embodiments may be recognized. [Brief explanation of the drawings]

[0012] [Figure 1] 1 shows a schematic side view of an evaporation system having one or more cylindrical evaporation assemblies according to one or more embodiments of the present disclosure. [Figure 2] 1 shows a schematic perspective view of a cylindrical evaporation assembly according to one or more embodiments of the present disclosure. [Figure 3] 1 shows a flow diagram of a method for coating a substrate according to one or more embodiments of the present disclosure.

[0013] For ease of understanding, the same reference numerals have been used, where possible, in the figures to refer to identical common elements, and it is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without the need for further recitation. DETAILED DESCRIPTION OF THE INVENTION

[0014] Vacuum web coating for anode prelithiation and solid metal anode deposition generally involves the deposition of thick (e.g., 3-20 microns) metal (e.g., lithium) layers onto single- or double-sided flexible substrates, such as metal current collectors (e.g., copper foil, nickel foil, or metallized plastic webs), graphite-coated substrates, or polymeric substrates (e.g., polyethylene terephthalate (PET) substrates). One deposition technique is thermal evaporation. Thermal evaporation occurs easily when source material is heated in an open crucible within a vacuum chamber to a temperature such that there is sufficient source vapor flow to condense on the cooler substrate. The source material can be heated indirectly by heating the crucible, or directly by a high-current electron beam directed at the source material confined in the crucible.

[0015] Conventional evaporator systems often require high temperatures (e.g., approximately 200-1500 degrees Celsius) for evaporation, thus placing a large heat load on the processed web or substrate. Furthermore, conventional evaporator systems that use cooling drums apply large tensions (e.g., 200-800 N) to the web to increase contact pressure on the cooling drum. Additionally, conventional evaporator systems suffer from high radiant heat loads due to the large surface area of ​​the evaporator body in close proximity to the substrate. Furthermore, conventional evaporator systems often use crucibles with external heaters. These external heaters can increase the combined radiant and condensation heat loads, further increasing the heat load.

[0016] Increased heat load and contact pressure can have several drawbacks. For example, increased heat load and contact pressure can cause wrinkling of the processed web, which can cause the web to tear during processing, potentially adversely affecting the final product after coating. Furthermore, current evaporator systems are often highly sensitive to the tilt angle of deposition, which can create additional challenges when deposition occurs above a cooling drum. Additionally, some conventional evaporator systems include complex two-body designs that are highly susceptible to leaks in high-temperature environments, thus increasing material costs.

[0017] The thermal evaporators described herein include porous media evaporator designs capable of evaporating materials for deposition at high rates with significantly lower evaporation heat loads. The porous media evaporator designs of the present disclosure eliminate the external crucible heaters found in currently available evaporator designs. Eliminating the external crucible heaters reduces power consumption and heat load on the web substrate. The porous media evaporator designs of the present disclosure minimize heat loss. The porous media evaporator designs are less sensitive to tilt angles relative to the substrate. Additionally, wrinkling of the web substrate is significantly reduced due to the lower heat load of the porous media evaporator designs.

[0018] FIG. 1 shows a schematic side view of an evaporation system 100 including one or more porous media thermal evaporation assemblies 140a-140e (collectively, 140) according to one or more embodiments of the present disclosure. The evaporation system 100 can be a roll-to-roll system configured to deposit a coating on a web material, such as depositing a metal-containing film stack according to the described embodiments. In one example, the evaporation system 100 can be used to deposit a metal or metal alloy. For example, the evaporation system 100 and the porous media thermal evaporation assembly 140 can be used to deposit a metal or metal alloy. Examples of metals and metal alloys include, but are not limited to, alkali metals (e.g., lithium or sodium), selenium, magnesium, zinc, cadmium, aluminum, gallium, indium, thallium, tin, lead, antimony, bismuth, tellurium, alkaline earth metals, silver, or combinations thereof. These metals or metal alloys can be used in the fabrication of energy storage devices, particularly in film stacks for lithium-containing anode structures. The evaporation system 100 includes a chamber body 102 that defines a common processing environment 104 in which some or all of the processing operations for depositing a coating on a web material can be performed. In one example, the common processing environment 104 can operate as a vacuum environment. In another example, the common processing environment 104 can operate as an inert gas environment. In some examples, the common processing environment 104 can be configured to operate at a pressure of, for example, 1×10 -4 mbar or less, such as 1×10 -3 A processing pressure of 0.1 mbar or less can be maintained.

[0019] The evaporation system 100 is configured as a roll-to-roll system including a payout reel 106 for supplying a continuous flexible substrate 108 or web, a coating drum 110 onto which the continuous flexible substrate 108 is processed, and a take-up reel 112 for collecting the processed continuous flexible substrate 108. The coating drum 110 includes a deposition surface 111 along which the continuous flexible substrate 108 moves, and material is deposited onto the continuous flexible substrate 108 as it moves across the deposition surface 111. The evaporation system 100 can further include one or more auxiliary transfer reels 114, 116 disposed between the payout reel 106, the coating drum 110, and the take-up reel 112. According to one embodiment, at least one of the one or more auxiliary transfer reels 114, 116, the payout reel 106, the coating drum 110, and the take-up reel 112 can be driven and rotated by a motor. In one example, the motor is a stepper motor. Although the supply reel 106, coating drum 110, and take-up reel 112 are shown as being located within a common processing environment 104, it should be understood that the supply reel 106 and take-up reel 112 can be located in separate chambers or modules. For example, at least one of the supply reels 106 can be located in a supply module, the coating drum 110 can be located in a processing module, and the take-up reel 112 can be located in a supply module.

[0020] The supply reel 106, the coating drum 110, and the take-up reel 112 can be individually temperature controlled. For example, the supply reel 106, the coating drum 110, and the take-up reel 112 can be individually heated using an internal or external heat source located inside each reel.

[0021] In one embodiment, which can be combined with other embodiments, one or more porous media thermal evaporation assemblies 140 can be removably coupled to a containment shield (not shown). In another embodiment, which can be combined with other embodiments, one or more porous media thermal evaporation assemblies 140 can be spaced apart from the coating drum 110. The one or more porous media thermal evaporation assemblies 140 are positioned to provide evaporated coating material onto the continuous flexible substrate 108 as the continuous flexible substrate 108 moves through the deposition zone 120 above the deposition surface 111 of the coating drum 110.

[0022] The deposition zone 120 is defined between one or more porous media thermal evaporation assemblies 140 and the deposition surface 111 of the coating drum 110. In one embodiment, which can be combined with other embodiments, the deposition zone 120 provides an isolated processing area within the common processing environment 104 of the chamber body 102. The deposition zone 120 can be minimized to fit a web, such as a continuous flexible substrate 108 wrapped around a cylindrical cooling drum, such as the coating drum 110, a planar cooling plate, or in a free-span orientation. In one embodiment, which can be combined with other embodiments, the deposition zone 120 is defined by at least one containment shield disposed between the porous media thermal evaporator assembly 140 and the coating drum 110. The containment shield defines the deposition zone 120 to confine the vaporized coating material to be deposited.

[0023] The one or more porous media thermal evaporation assemblies 140 are described in further detail with reference to FIG. 2. The one or more porous media thermal evaporation assemblies 140 are arranged to perform one or more processing operations on a continuous flexible substrate 108 or web of material. In one example, as shown in FIG. 1, the one or more porous media thermal evaporation assemblies 140 are arranged radially around the coating drum 110. Additionally, non-radial arrangements are also contemplated. In one embodiment, which can be combined with other embodiments, the one or more porous media thermal evaporation assemblies 140 include a lithium (Li) source. Additionally, the one or more porous media thermal evaporation assemblies 140 can include a source of an alloy of two or more metals. The coating material to be deposited can be evaporated, for example, by thermal evaporation techniques.

[0024] During operation, the one or more porous media thermal evaporation assemblies 140 emit a plume of evaporated coating material 122 that is attracted to the continuous flexible substrate 108, forming a deposited film of the material on the continuous flexible substrate 108.

[0025] Additionally, while five porous media thermal evaporation assemblies 140a-140e are shown in FIG. 1, it should be understood that any number of evaporation assemblies can be used. Furthermore, evaporation system 100 can further include one or more additional deposition sources. For example, the one or more deposition sources described include an electron beam source, as well as additional sources that can be selected from the group consisting of CVD sources, PECVD sources, and various PVD sources. Exemplary PVD sources include sputtering sources, electron beam evaporation sources, and thermal evaporation sources. Furthermore, these additional deposition sources can be positioned radially relative to deposition surface 111 of coating drum 110.

[0026] In one embodiment of the present disclosure, which can be combined with other embodiments, the evaporation system 100 is configured to treat both sides of a continuous flexible substrate 108. For example, an additional evaporation assembly similar to one or more porous media thermal evaporation assemblies 140 can be positioned to treat the opposite side of the continuous flexible substrate 108. While the evaporation system 100 is configured to treat a horizontally oriented continuous flexible substrate 108, the evaporation system 100 can also be configured to treat substrates oriented in other directions, such as a vertically oriented continuous flexible substrate 108. In one embodiment of the present disclosure, which can be combined with other embodiments, the continuous flexible substrate 108 is a flexible polymer substrate, such as a polyethylene terephthalate (PET) substrate, a flexible conductive substrate, such as a copper foil substrate, or a combination of both. In one embodiment of the present disclosure, which can be combined with other embodiments, the continuous flexible substrate 108 comprises a conductive substrate having one or more layers formed thereon. In one embodiment of the present disclosure, which can be combined with other embodiments, the conductive substrate is a copper substrate.

[0027] Evaporation system 100 further includes a gas panel 160. Gas panel 160 uses one or more conduits (not shown) to deliver process gases to evaporation system 100. Gas panel 160 can include mass flow controllers and shut-off valves to control the gas pressure and flow rate of each individual gas delivered to evaporation system 100. Examples of gases that can be delivered by gas panel 160 include, but are not limited to, inert gases (e.g., argon) for pressure control, etching chemicals used for in-situ cleaning of evaporation system 100, such as, but not limited to, diketones, and deposition chemicals, such as, but not limited to, 1,1,1,2-tetrafluoroethane or other hydrofluorocarbons, and trimethylaluminum, titanium tetrachloride, or other metal-organic precursors used for in-situ surface modification of reactive lithium mixed conductors tens of nanometers thick.

[0028] The evaporation system 100 further includes a system controller 170 that can operate to control various aspects of the evaporation system 100. The system controller 170 facilitates control and automation of the evaporation system 100 and can include a central processing unit (CPU), memory, and support circuitry (or I / O). Software instructions and data can be encoded and stored in the memory for instructing the CPU. The system controller 170 can communicate with one or more of the evaporation system 100 components, for example, via a system bus. A program (or computer instructions) readable by the system controller 170 determines which tasks can be performed on the substrate. In some embodiments, the program is software readable by the system controller 170, which can include code for monitoring chamber conditions, including independent temperature control of one or more porous media thermal evaporation assemblies 140. While only one system controller, i.e., system controller 170, is shown, it should be understood that multiple system controllers can be used in the described embodiments.

[0029] The evaporation system 100 may further include a power supply 180 for providing power to the components of the evaporation system 100. For example, the power supply 180 may be electrically connected to one or more heat sources within the porous media heat evaporator assembly 140.

[0030] The evaporation system 100 may further include a coating material supply 190 for supplying coating material to each of the porous media heat evaporator assemblies 140. In one embodiment, which can be combined with other embodiments, the coating material supply maintains the coating material in liquid form.

[0031] In some embodiments, each porous media heat evaporator assembly 140a-e is spaced about 22 to about 26 centimeters from an adjacent porous media heat evaporator assembly. In such embodiments, the coating drum 110 is a gas cushion drum cooled to a range of about -10 degrees Celsius to about 50 degrees Celsius, the speed of travel of the continuous flexible substrate is about 2 meters / minute, and therefore the linear cooling time between the nozzles of adjacent porous media heat evaporator assemblies 140a-e is about 12 to 13 seconds.

[0032] FIG. 2 shows a schematic cross-sectional view of the porous media evaporator assembly 140. The porous media evaporator assembly 140 includes a porous media evaporator 214. The porous media evaporator 214 is designed to hold and evaporate a coating material to be evaporated, such as a metal or metal alloy. The porous media evaporator 214 includes an evaporator body 212, a coating material container 216, and one or more heaters 209. The evaporator body 212 includes an evaporator sidewall 213, and the coating material container 216 includes a container sidewall 217. The evaporator sidewall 213 defines an evaporator volume 215 and an evaporator opening 211. The container sidewall 217 defines a coating material volume 219. A porous media 220 and a coating material container 227 are disposed within the coating material container 216. The coating material container 227 is configured to receive the coating material from the coating material source 190 and contain the coating material within the coating material container 216. A vessel isolator 218 separates the coating material volume 219 from the evaporator volume 215. The vessel isolator 218 prevents heat radiation from the coating material vessel 216 from consuming the thermal budget of the substrate 108.

[0033] Porous media 220 is partially immersed in coating material vessel 227. Porous media 220 extends from coating material vessel 227 and coating material vessel 216 through media opening 221 in vessel isolator 218. Porous media 220 extends partially into evaporator volume 215.

[0034] In some embodiments, the porous medium 220 may comprise an iron-based material, such as sintered porous stainless steel, pleated stainless steel, tungsten (W), titanium (Ti), tantalum (TA), or a combination thereof. In other embodiments, the porous medium may be a porous mesh. In yet other embodiments, the porous medium 220 may comprise a porous cylinder disposed around the porous medium 220. In yet other embodiments, the porous medium 220 may be an array of tubular media. The porous cylinder may comprise micron-sized porous pores in a linear or spiral pattern. The porous pores may be about 20 μm to about 100 μm in diameter. The pore size of the porous medium 220 is about 1 μm to about 500 μm. In various embodiments, the exposed portion of the porous medium 220 (e.g., not immersed in the coating material bath 227) has a surface area that is at least 25% greater than the surface area of ​​the portion of the porous medium 220 that is immersed in the coating material bath 227.

[0035] The heater 209 is disposed around the porous media evaporator 214. The heater 209 is configured to heat the porous media evaporator 214 to a temperature between about 150°C and 400°C, for example, between about 186°C and about 350°C.

[0036] A supply line (not shown) supplies the coating material to the coating material reservoir 227. The coating material is metered into the coating material reservoir 227 at a rate of up to about 500 cc / min. The porous medium 220 is configured to absorb the coating material by capillary forces. As the coating material is absorbed into the porous medium 220, it rises through the porous medium 220 and exits the coating material reservoir 216. In some embodiments, the porous medium 220 may be heated to a temperature between about 150°C and 400°C, such as between about 186°C and about 350°C, to maintain the melting temperature of the coating material. In other embodiments, the porous medium 220 is heated from the coating material reservoir 227. The coating material evaporates as it travels through the porous medium 220, releasing coating material vapor through the sidewalls of the porous medium 220 into the evaporation volume 215.

[0037] The porous medium 220 has a length L1 of about 25 mm to about 100 mm. The porous medium may be an array of rods, an array of cylinders, a cylinder, a rectangular pillar, or an array of rectangular pillars. The rods may have a diameter of about 10 mm to about 20 mm. The cylinders may have an outer diameter of about 10 mm to about 25 mm and a wall thickness of about 1 mm to about 6 mm. The array of rectangular pillars may have a square cross section with a width of about 10 mm to about 25 mm and a wall thickness of about 1 mm to about 6 mm. The porous medium 220 creates a large surface area for evaporation of the coating material. Therefore, a small amount of coating material can generate a large amount of coating material vapor.

[0038] The radiant heat incident on the substrate 108 is expressed as T 4 The surface area of ​​the porous medium 220, combined with the reduced amount of coating material melting in the porous medium 220, allows for a reduction in the temperature of the porous medium 220 and therefore a reduction in the radiant heat incident on the substrate 108.

[0039] The reduced size of the coating material vessel 227 compared to open-vessel evaporators allows for a reduced amount of coating material to be used in the coating process and reduces the cooling time of the system after processing due to the reduced volume of coating material that must be cooled. Additionally, the reduced size of the coating material vessel 227 allows for more efficient refilling of the coating material vessel 227 during the coating process.

[0040] In some embodiments, the evaporator opening 211 includes one or more nozzles. The nozzles can allow for more precise deposition of the coating material onto the substrate 108. To prevent clogging of the nozzles during the deposition process, the nozzles must be heated to a temperature higher than the temperature of the evaporator. Reducing the radiant heat of the porous media evaporator 214 allows for reduced radiant heat of the nozzles, and therefore, a reduced thermal budget consumed by the substrate 108 during processing.

[0041] 3 shows a flow diagram of a method 300 for coating a substrate 108. Method 300 begins with step 301, in which a substrate 108 is provided to an evaporation system 100. In various embodiments, evaporation system 100 includes a supply reel 106, a coating drum 110, a take-up reel 112, a coating material supply 190, and a power supply 180. The substrate 108 moves through evaporation system 100 via supply reel 106, coating drum 110, and take-up reel 112.

[0042] In step 302, coating material is supplied to porous media evaporator 214. The coating material is supplied from coating material source 190 to a coating material reservoir 227 disposed within porous media evaporator 214. Porous media evaporator 214 is disposed within evaporation system 100. Porous media evaporator 214 includes porous media 220, an evaporator volume 215 defined by an evaporator body 212, and a coating material volume 219 defined by a coating material reservoir 216. The coating material reservoir is disposed within coating material volume 219. Porous media 220 has a porosity between about 2 μm and about 500 μm. The coating material is metered into gap 226 at a rate of up to about 500 cc / min.

[0043] In step 303, the porous medium 220 is heated. The porous medium 220 is heated to a temperature of about 150°C to about 400°C, for example, about 186°C to about 350°C, to maintain the melting temperature of the coating material. In some embodiments, the porous medium 220 is heated using a heater. In other embodiments, the porous medium 220 is heated from a coating material bath 227.

[0044] In step 304, the porous media 220 absorbs the coating material. The coating material is absorbed into the porous media 220 by capillary forces. The capillary forces move the coating material from the coating material volume 219 to the evaporator volume 215.

[0045] In step 305, the porous media 220 evaporates the coating material to form a coating material vapor that is emitted from the sidewalls of the porous media 220 into the evaporator volume.

[0046] In step 306, the substrate 108 is coated with a vapor of the coating material. The thickness of the coating material deposited on the substrate 108 is greater than about 1 μm, for example, up to about 20 μm.

[0047] In summary, a porous media evaporator is disclosed. The porous media evaporator uses capillary forces to absorb coating material from a coating material reservoir and evaporate the coating material into the evaporator volume. The porous media allows for a large surface area for generating coating material vapor from a small amount of coating material. Requiring a smaller amount of coating material allows for less radiant heat from the evaporator, resulting in a reduced thermal budget consumed by the substrate 108. Furthermore, requiring a smaller amount of coating material allows for faster cooling times for the porous media evaporator and more efficient refilling of the coating material reservoir.

[0048] According to some embodiments, evaporation processes and evaporation apparatuses are provided for depositing layers on substrates, such as flexible substrates. Accordingly, flexible substrates can be considered to include, among other things, films, foils, webs, and strips of plastic, metal, or other materials. Typically, terms such as "web," "foil," "strip," and "substrate" are used synonymously. According to some embodiments, evaporation process components, evaporation process apparatus, and evaporation processes according to the described embodiments can be provided for the flexible substrates described above. However, they may also be provided in connection with non-flexible substrates, such as glass substrates, that are subjected to a reactive deposition process from an evaporation source.

[0049] When introducing elements of the present disclosure or exemplary aspects or embodiments thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the element.

[0050] The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0051] While the foregoing is directed to several embodiments of the present disclosure, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, which scope is determined by the following claims.

Claims

1. 1. An evaporator assembly comprising: evaporator sidewall, an evaporator volume defined by the evaporator sidewall; and an opening defined by the evaporator sidewall; an evaporator body comprising: Container sidewall, a coating material volume defined by said container sidewall; a coating material reservoir disposed within the coating material volume; and a porous medium disposed partially within the coating material reservoir and partially within the evaporator volume; a coating material container comprising: an evaporator assembly having

2. The evaporator assembly of claim 1 , wherein the porous media has a length of about 25 mm to about 100 mm.

3. The evaporator assembly of claim 1 , wherein the porous media has a diameter of about 10 mm to about 25 mm.

4. The evaporator assembly of claim 1 , wherein the porous media is configured to absorb coating material provided to the coating material reservoir.

5. The evaporator assembly of claim 3 , wherein the porous media is configured to absorb the coating material using capillary forces.

6. The evaporator assembly of claim 1 , wherein the coating material container further comprises a container isolator configured to isolate the coating material volume from the evaporator volume.

7. The evaporator assembly of claim 1 , wherein the porous media has a porosity of about 1 μm to about 500 μm.

8. The evaporator assembly of claim 1 , wherein the porous media comprises sintered porous stainless steel, pleated stainless steel, a porous mesh, or an array of tubular media.

9. The evaporator assembly of claim 1 further comprising a porous cylinder disposed around the porous media.

10. The evaporator assembly of claim 1 , wherein the porous media comprises pores in a linear or spiral pattern.

11. The evaporator assembly of claim 10, wherein the holes have a diameter of about 20 μm to about 100 μm.

12. 1. An evaporation system comprising one or more evaporation assemblies, each of the one or more evaporation assemblies evaporator sidewall, an evaporator volume defined by the evaporator sidewall; and an opening defined by the evaporator sidewall; an evaporator body comprising: Container sidewall, a coating material volume defined by said container sidewall; a coating material reservoir disposed within the coating material volume; and a porous medium disposed partially within the coating material reservoir and partially within the evaporator volume; a coating material container comprising: An evaporation system having:

13. The evaporation system of claim 12 , wherein the porous media comprises sintered porous stainless steel, pleated stainless steel, a porous mesh, or an array of tubular media.

14. The evaporative system of claim 12 , wherein the porous media comprises pores in a linear or spiral pattern.

15. The evaporation system of claim 14, wherein the holes have a diameter of about 20 μm to about 100 μm.

16. The evaporation system of claim 12, wherein the porous media has a pore size of about 1 μm to about 500 μm.

17. 1. A method of coating a substrate, comprising: providing a substrate to an evaporation system; providing a coating material to an evaporator; heating the porous medium of the evaporator; absorbing the coating material into the porous medium; evaporating the coating material to form a coating material vapor; and coating the substrate with a vapor of the coating material; A method comprising:

18. 20. The method of claim 17, wherein absorbing the coating material into the porous medium occurs by capillary forces.

19. 18. The method of claim 17, further comprising heating the porous media to a temperature of from about 186°C to about 350°C.

20. The method of claim 17, wherein the porous media has a porosity of from about 1 μm to about 500 μm.

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