TECHNICAL FIELD

[0001] The present disclosure generally relates to an evaporation system for providing a gas for a reactive deposition process. More particularly, the present disclosure generally relates to a thermal evaporator design, which provides a uniform evaporation rate at relatively low temperatures.

BACKGROUND

[0002] Processing of flexible substrates, such as plastic films or foils, is in high demand in the packaging industry, semiconductor industry, and other industries. Processing can include coating of a flexible substrate with a chosen material, such as a metal. The economical production of these coatings is limited by the thickness uniformity necessary for the product, the reactivity of the coating materials, the cost of the coating materials, and the deposition rate of the coating materials. The most demanding applications generally involve deposition in a vacuum chamber for precise control of the coating thickness and the optimum optical properties. The high capital cost of vacuum coating equipment necessitates a high throughput of coated area for large-scale commercial applications. The coated area per unit time is typically proportional to the coated substrate width and the vacuum deposition rate of the coating material.

[0003] A deposition process that can utilize a large vacuum chamber has tremendous economic advantages. Vacuum coating chambers, substrate treating and handling equipment, and pumping capacity, increase in cost less than linearly with chamber size. Therefore, the most economical process for a fixed deposition rate and coating design will utilize the largest substrate available. A larger substrate can generally be fabricated into discrete parts after the coating process is complete. In the case of products manufactured from a continuous web, the web is slit or sheet cut to either a final product dimension or a narrower web suitable for the subsequent manufacturing operations. [0004] One technique used for deposition is thermal evaporation. Thermal evaporation takes place when a source material is heated in an open crucible within a vacuum chamber when a temperature is reached such that there is a sufficient vapor flux from the source for condensation on a cooler substrate. The source material can be heated indirectly by heating the crucible, or directly by a high current electron beam directed into the source material confined by the crucible. Thermal evaporation typically takes place at high temperatures, which can lead to high thermal loads on the substrate being processed. These high thermal loads can damage the substrate. One method for reducing thermal load includes cooling the crucible through radiative cooling. However, radiative cooling is typically very slow, which can lead to significant chamber downtime and an increase in cost of ownership.

[0005] In addition, current thermal evaporator designs, which use external heaters can suffer from radiative heat loss, which can lead to increased power consumption to achieve targeted temperatures.

[0006] Thus, there is a need for apparatus and methods for reducing the thermal load on substrates during thermal evaporation processes.

SUMMARY

[0007] The present disclosure generally relates to an evaporation system for providing a gas for a reactive deposition process. More particularly, the present disclosure generally relates to a thermal evaporator design, which provides a uniform evaporation rate at relatively low temperatures.

[0008] In one aspect, an evaporator assembly is provided. The evaporator assembly includes an evaporation body, an evaporator, and one or more external heaters. The evaporator body includes an evaporator wall, a collection volume defined by the evaporator wall, and an evaporator opening. The evaporator includes a first end, a second end, a porous media spanning between the first end and the second end, an inner tube disposed within the porous media, a coating material feed line, and an internal heater disposed within the inner tube. A gap is defined between the inner tube and the porous media. The evaporator is configured to rotate such that a coating material fed into the gap from the coating material feed line is sprayed from the porous media.

[0009] In another aspect, an evaporator system is disclosed. The evaporator system includes one or more evaporation assemblies, an unwinding reel, a coating drum, and a winding reel. The one or more evaporation assemblies include an evaporation body, an evaporator, and one or more external heaters. The evaporator body includes an evaporator wall, a collection volume defined by the evaporator wall, and an evaporator opening. The evaporator includes a first end, a second end, a porous media spanning between the first end and the second end, an inner tube disposed within the porous media, a coating material feed line, and an internal heater disposed within the inner tube. A gap is defined between the inner tube and the porous media. The evaporator is configured to rotate such that a coating material fed into the gap from the coating material feed line is sprayed from the porous media.

[0010] In yet another aspect, a method is disclosed. The method includes providing a substrate to an evaporation system; feeding a coating material to an evaporator; heating a coating material with an internal heater of the evaporator; rotating the evaporator to cause the coating material to be sprayed from the evaporator; and coating the substrate with the coating material.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] So that the manner in which the recited features of the present disclosure can be understood in detail, a more particular description of the aspects, briefly summarized above, may be had by reference to implementations, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical implementations of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective implementations.

[0012] FIG. 1 illustrates a schematic side view of an evaporation system having one or more centrifugal atomization evaporation assemblies in accordance with one or more implementations of the present disclosure. [0013] FIG. 2A illustrates a schematic cross-sectional view of a centrifugal atomization evaporation assembly in accordance with one or more implementations of the present disclosure.

[0014] FIG. 2B illustrates a schematic perspective view of the centrifugal atomization evaporation assembly of FIG. 2A in accordance with one or more implementations of the present disclosure.

[0015] FIG. 2C illustrates a schematic cross-sectional perspective view of the centrifugal atomization evaporation assembly of FIG. 2A in accordance with one or more implementations of the present disclosure.

[0016] FIG. 2D illustrates a schematic cross-sectional perspective view of a portion of the centrifugal atomization evaporation assembly of FIG. 2A in accordance with one or more implementations of the present disclosure.

[0017] FIG. 3A illustrates a schematic perspective view of a portion of a v-groove porous cylinder in accordance with one or more implementations of the present disclosure.

[0018] FIG. 3B illustrates a schematic perspective view of a portion of a rectangular groove porous cylinder in accordance with one or more implementations of the present disclosure.

[0019] FIG. 3C illustrates a schematic perspective view of a portion of a u-groove porous cylinder in accordance with one or more implementations of the present disclosure.

[0020] FIG. 3D illustrates a schematic perspective view of a portion of a spiral groove porous cylinder in accordance with one or more implementations of the present disclosure.

[0021] FIG. 3E illustrates a schematic perspective view of a portion of a blind-hole porous cylinder in accordance with one or more implementations of the present disclosure. [0022] FIG. 4 illustrates a schematic cross-sectional view of an alternative centrifugal atomization evaporation assembly in accordance with one or more implementations of the present disclosure.

[0023] FIG. 5 illustrates a flow chart of a method of coating a substrate in accordance with one or more implementations of the present disclosure.

[0024] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one implementation may be beneficially incorporated in other implementations without further recitation.

DETAILED DESCRIPTION

[0025] Vacuum web coating for anode pre-lithiation and solid metal anode deposition generally involves thick (e.g., three to twenty micron) metallic (e.g., lithium) deposition on single-side-coated or double-side-coated flexible substrates, for example, metallic current collectors, such as, copper foil, nickel foil, or metallized plastic web, graphite-coated substrates, or polymer substrates (e.g., polyethylene terephthalate (PET) substrates). One technique for deposition is thermal evaporation. Thermal evaporation readily takes place when a source material is heated in an open crucible within a vacuum chamber when a temperature is reached such that there is a sufficient vapor flux from the source for condensation on a cooler substrate. The source material can be heated indirectly by heating the crucible, or directly by a high current electron beam directed into the source material confined by the crucible.

[0026] Conventional evaporator systems often involve high temperatures (e.g., approximately 200 to 1500 degrees Celsius) to evaporate, thus placing a high thermal load on the processed web or substrate. Conventional evaporator systems, which use cooling drums also place higher tension on the web (e.g., 200 N to 800 N) to increase contact pressure on the cooling drum. In addition, conventional evaporator systems suffer from high radiative heat load due to the large surface area of the evaporator body at close proximity to the substrate. In addition, conventional evaporator system often use crucibles with external heaters. These external heaters can increase the combined radiative and condensation heat load, further increasing thermal load. [0027] The increased thermal loads and contact pressures can have several drawbacks. For example, the increased thermal loads and contact pressures can lead to wrinkling of the processed web, can lead to tearing of the web during processing, and can affect the final product after coating. Further, current evaporator systems are often very sensitive to the inclination angle of deposition, which can present additional challenges when deposition takes place over a cooling drum. In addition, some conventional evaporator systems include complex two-body designs, which are very susceptible to leaks in a hot environment, thus increasing material costs.

[0028] The thermal evaporator described herein includes a centrifugal atomization evaporator design, which can evaporate material for deposition at high rates with significantly lower heat loads for evaporation. The centrifugal atomization evaporator design of the present disclosure reduces the temperature of the external crucible heater found in currently available evaporator designs. Reduction of the temperature of the external crucible heater reduces power consumption and decreases the heat load on the web substrate. The centrifugal atomization evaporator design of the present disclosure minimizes heat loss. The centrifugal atomization evaporator design is not sensitive to the inclination angle relative to the substrate. In addition, due to the lower thermal heat load of the centrifugal atomization evaporator design, wrinkling of the web substrate is significantly reduced.

[0029] FIG. 1 illustrates a schematic side view of an evaporation system 100 including one or more centrifugal atomization evaporation assemblies 140a-140e (collectively 140), in accordance with one or more implementations of the present disclosure. The evaporation system 100 can be a roll-to-roll system adapted for depositing coatings on web materials, for example, for depositing metal containing film stacks according to the implementations described. In one example, the evaporation system 100 can be used for depositing metals or metal alloys. For example, the evaporation system 100 and the centrifugal atomization evaporation assembly 140 can be used for depositing metals or metal alloys. Examples of metal 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, alkali earth metals, silver, or a combination thereof. These metals or metal alloys can be used for manufacturing energy storage devices, and particularly for 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 actions for depositing coatings on web materials can be performed. In one example, the common processing environment 104 is operable as a vacuum environment. In another example, the common processing environment 104 is operable as an inert gas environment. In some examples, the common processing environment 104 can be maintained at a process pressure of 1 x 10’ ³ mbar or below, for example, 1 x 10’ ⁴ mbar or below.

[0030] The evaporation system 100 is constituted as a roll-to-roll system including an unwinding reel 106 for supplying a continuous flexible substrate 108 or web, a coating drum 110 over which the continuous flexible substrate 108 is processed, and a winding reel 112 for collecting the continuous flexible substrate 108 after processing. The coating drum 110 includes a deposition surface 111 over which the continuous flexible substrate 108 travels while material is deposited onto the continuous flexible substrate 108. The evaporation system 100 can further include one or more auxiliary transfer reels 114, 116 positioned between the unwinding reel 106, the coating drum 110, and the winding reel 112. According to one aspect, at least one of the one or more auxiliary transfer reels 114, 116, the unwinding reel 106, the coating drum 110, and the winding reel 112 can be driven and rotated by a motor. In one example, the motor is a stepper motor. Although the unwinding reel 106, the coating drum 110, and the winding reel 112 are shown as positioned in the common processing environment 104, it should be understood that the unwinding reel 106 and the winding reel 112 can be positioned in separate chambers or modules. For example, at least one of the unwinding reel 106 can be positioned in an unwinding module, the coating drum 110 can be positioned in a processing module, and the winding reel 112 can be positioned in an unwinding module.

[0031] The unwinding reel 106, the coating drum 110, and the winding reel 112 can be individually temperature controlled. For example, the unwinding reel 106, the coating drum 110, and the winding reel 112 can be individually heated using an internal heat source positioned within each reel or an external heat source. [0032] In one implementation, which can be combined with other implementations, the one or more centrifugal atomization evaporation assembly 140 can be removably coupled with the containment shield (not shown). In another implementation, which can be combined with other implementations, the one or more centrifugal atomization evaporation assemblies 140 can be spaced apart from the coating drum 110. The one or more centrifugal atomization evaporation assemblies 140 are positioned to deliver evaporated coating material onto the continuous flexible substrate 108 as the continuous flexible substrate 108 travels through a deposition zone 120 over the deposition surface 111 of the coating drum 110.

[0033] The deposition zone 120 is defined in between the one or more centrifugal atomization evaporation assembly 140 and the deposition surface 111 of the coating drum 110. In one implementation, which can be combined with other implementations, the deposition zone 120 provides an isolated processing region within the common processing environment 104 of the chamber body 102. The deposition zone 120 can be minimized and defined to conform to a web, for example, the continuous flexible substrate 108 that is wound on a cylindrical cooling drum, such as the coating drum 110, a planar cooling plate, or in a free span orientation. In one implementation, which can be combined with other implementations, the deposition zone 120 is defined by at least one containment shield (See FIG. 7) disposed between the centrifugal atomization evaporation assembly 140 and the coating drum 110. The containment shield defines the deposition zone 120 for confinement of the evaporated coating material to be deposited.

[0034] The one or more centrifugal atomization evaporation assembly 140 will be described in greater detail with reference to FIGS. 2A-4. The one or more centrifugal atomization evaporation assemblies 140 are positioned to perform one or more processing operations to the continuous flexible substrate 108 or web of material. In one example, as depicted in FIG. 1 , the one or more centrifugal atomization evaporation assemblies 140 are radially disposed about the coating drum 110. In addition, arrangements other than radial are contemplated. In one implementation, which can be combined with other implementations, the one or more centrifugal atomization evaporation assemblies 140 include a lithium (Li) source. Further, the one or more centrifugal atomization evaporation assemblies 140 can also 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.

[0035] In addition, although five centrifugal atomization evaporation assemblies 140a-140e are shown in FIG. 1 , it should be understood that any number of evaporation assemblies can be used. In addition, the evaporation system 100 can further include one or more additional deposition sources. For example, the one or more deposition sources as described include an electron beam source and additional sources, which can be selected from the group of CVD sources, PECVD sources, and various PVD sources. Exemplary PVD sources include sputtering sources, electron beam evaporation sources, and thermal evaporation sources. In addition, these additional deposition sources can be positioned radially relative to the deposition surface 111 of the coating drum 110.

[0036] In one implementation of the present disclosure, which can be combined with other implementations, the evaporation system 100 is configured to process both sides of the continuous flexible substrate 108. For example, additional evaporation assemblies similar to the one or more centrifugal atomization evaporation assemblies 140 can be positioned to process the opposing side of the continuous flexible substrate 108. Although the evaporation system 100 is configured to process the continuous flexible substrate 108, which is horizontally oriented, the evaporation system 100 can be configured to process substrates positioned in different orientations, for example, the continuous flexible substrate 108 can be vertically oriented. In one implementation of the present disclosure, which can be combined with other implementations, the continuous flexible substrate 108 is a flexible polymer substrate, for example, a polyethylene terephthalate “PET” substrate, a flexible conductive substrate, such as a copper material, graphite material, silicon material, or a combination of thereof. In one implementation of the present disclosure, which can be combined with other implementations, the continuous flexible substrate 108 includes a conductive substrate with one or more layers formed thereon. In one implementation of the present disclosure, which can be combined with other implementations, the conductive substrate is a copper substrate. [0037] The evaporation system 100 further includes a gas panel 160. The gas panel 160 uses one or more conduits (not shown) to deliver processing gases to the evaporation system 100. The gas panel 160 can include mass flow controllers and shut-off valves, to control gas pressure and flow rate for each individual gas supplied to the evaporation system 100. Examples of gases that can be delivered by the gas panel 160 include, but are not limited to, inert gases for pressure control (e.g., argon), etching chemistries including but not limited to diketones used for in-situ cleaning of the evaporation system 100, and deposition chemistries including 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 tens of nanometer thick reactive lithium mixed conductor surface modification.

[0038] The evaporation system 100 further includes a system controller 170 operable to control various aspects of the evaporation system 100. The system controller 170 facilitates the control and automation of the evaporation system 100 and can include a central processing unit (CPU), memory, and support circuits (or I/O). Software instructions and data can be coded and stored within the memory for instructing the CPU. The system controller 170 can communicate with one or more of the components of evaporation system 100 via, for example, a system bus. A program (or computer instructions) readable by the system controller 170 determines which tasks are performable on a substrate. In some aspects, the program is software readable by the system controller 170, which can include code for monitoring chamber conditions, including independent temperature control of the one or more centrifugal atomization evaporation assembly 140. Although only a single system controller, the system controller 170 is shown, it should be appreciated that multiple system controllers can be used with the aspects described.

[0039] The evaporation system 100 may further include a power supply 180 for supplying power to the components of the evaporation system 100. For example, the power supply 180 may be electrically coupled with the one or more heating sources in the centrifugal atomization evaporation assembly 140.

[0040] The evaporation system 100 may further include a coating material supply source 190 for supplying coating material to each of the centrifugal atomization evaporator assemblies. In one implementation, which can be combined with other implementations, the coating material supply maintains the coating material in liquid form.

[0041] FIG. 2A illustrates a schematic cross-sectional view of a centrifugal atomization evaporation assembly 140. FIG. 2B illustrates a schematic perspective view of the centrifugal atomization evaporation assembly 140. FIG. 2C illustrates a schematic cross-sectional perspective view of the centrifugal atomization evaporation assembly 140. FIG. 2D illustrates a schematic cross-sectional perspective view of a portion of the centrifugal atomization evaporation assembly 140.

[0042] The centrifugal atomization evaporation assembly 140 is designed to hold and evaporate a coating material. The centrifugal atomization evaporation assembly 140 includes an evaporator body 212, a centrifugal atomization evaporator 214, and one or more external heaters 209. The evaporator body 212 includes an evaporator wall 213, a collection volume 215 defined by the evaporator wall 213, and an evaporator opening 217. The evaporator opening 217 has a width of about 1 mm to about 75 mm. Although the evaporator body 212 is shown as a rectangle or rectangular trough, other suitable shapes for the evaporator body 212 are also contemplated. The evaporator body 212 may comprise any suitable material having high thermal conductivity. In one implementation, which can be combined with other implementations, the evaporator body 212 comprises a material selected from molybdenum, graphite, stainless steel, boron nitride, titanium, or a combination thereof. The evaporator body 212 further includes a material collection funnel 219 and a material return pathway 221. The material collection funnel 219 is configured to collect excess coating material and funnel the excess coating material to the material return pathway 221 . The material return pathway 221 is configured to transport excess coating material to the coating material supply source 190. The external heaters 209 are configured to heat the evaporator wall 213 to facilitate the flow of the coating material to the material collection funnel 219 and the material return pathway 221 (e.g., the external heaters 209 melt the coating material deposited onto the evaporator walls 213). The external heaters 209 are configured to heat the centrifugal atomization evaporator 214 to a temperature of about 150°C to 400°C, such as about 186°C to about 350°C. [0043] The centrifugal atomization evaporator 214 holds and evaporates a coating material to be deposited. The centrifugal atomization evaporator 214 includes a first end 214a, a second end 214b, a porous media 220, and an inner tube 222. The porous media 220 spans between the first end 214a and the second end 214b. In some embodiments, the porous media 220 may include a ferrous material, e.g., a sintered porous stainless steel, a titanium material, a tungsten material, or any other suitable material. In other embodiments, the porous media 220 may be a porous mesh. In still other embodiments, the porous media 220 may include a porous cylinder disposed around the porous media 220. The porous cylinder may include micronsized holes in a linear or spiral pattern. The porous holes may be about 20 pm to about 100 pm in diameter. The porosity of the porous media 220 is between about 2 pm to about 500 pm.

[0044] In one embodiment, the inner tube 222 is a cylinder. The inner tube is disposed within the porous media 220. In other embodiments, other suitable shapes for the inner tube 222 are also contemplated. The porous media 220 of the centrifugal atomization evaporator 214 has an outer radius r1 of about 7 mm to about 125 mm. The porous media 220 of the centrifugal atomization evaporator 214 further has an inner radius r2. The thickness of the porous media 220 (e.g., the difference between the outer radius r1 and the inner radius r2) is about 1 mm to about 6 mm. The inner tube 222 defines an internal volume 230. The inner tube 222 includes stainless steel material, a titanium material, a tungsten material, or any other suitable material material. The inner tube includes an outer diameter r3.

[0045] The porous media 220 and the inner tube 222 define a gap 226. In particular, the gap 226 is defined between the inner diameter r2 of porous media 220 and the outer radius r3 of the inner tube 222. The gap has a width of about 0.5 mm to about 1 .5 mm such as about 1 .0 mm. The coating material may flow into the gap 226 between the porous media 220 and the inner tube 222. In some embodiments, the inner tube 222 may include a groove (e.g., a spiral groove) on the outer diameter of the inner tube 222. The groove may facilitate the metering of the flow of the coating material into the gap 226 to enable uniform flow of the coating material. The inner tube 222 having an internal volume 230 reduces the mass of the centrifugal atomization evaporator 214 by reducing the amount of space that is occupied by the coating material.

[0046] The distance between the first end 214a and the second end 214b opposite the first end 214a define a length L1 of the centrifugal atomization evaporator 214. The length L1 may be determined by the width of the substrate 108 that is processed. The length L1 is 1 meter or less, such as in a range from about 0.5 meters to about 1 meter. The first end 214a and the second end 214b each define a circumference of the centrifugal atomization evaporator 214.

[0047] The coating material is provided to the centrifugal atomization evaporator 214 from the coating material supply source 190 via a feed line 228 of the centrifugal atomization evaporation assembly 140. The feed line 228 provides the coating material at the first end 214a of the centrifugal atomization evaporator 214. In some embodiments, the feed line 228 may include a groove (e.g., a spiral groove) on the outer diameter of the feed line 228. The groove may facilitate the metering of the flow of the coating material into the gap 226 to enable uniform flow of the coating material and to prevent coating material leaks at the feedline interface.

[0048] An internal heater 224 is configured to heat the components of the centrifugal atomization evaporator 214 (e.g., the porous media 220 and the inner tube 222) to melt and evaporate the coating material. The internal heater 224 of the centrifugal atomization evaporation assembly 140 is partially disposed within the internal volume 230. The internal heater 224 is configured to heat the centrifugal atomization evaporator 214 to a temperature of about 150°C to 400°C, such as about 186°C to about 350°C.

[0049] The centrifugal atomization evaporation assembly 140 further includes a first end driver 232a and a second end driver 232b. The first end driver 232a is coupled to the first end 214a of the centrifugal atomization evaporator 214. The second end driver 232b is coupled to the second end 214b of the centrifugal atomization evaporator 214. A first end bearing 234a is configured to facilitate the rotation of the first end driver 232a. A second end bearing 234b is configured to facilitate the rotation of the second end driver 232b. A belt driver (not shown) is attached to the second end driver 232b. The belt driver may be a SS belt drive. In some embodiments, an electric motor rotates the centrifugal atomization evaporation assembly 140. The driver belt may be about 0.5 mm thick.

[0050] The feed line 228 is partially disposed in the first end driver 232a. The internal heater 224 is partially disposed in the second end driver 232b. The first end driver 332a and the second end driver 232b are configured to rotate the centrifugal atomization evaporation assembly 140. During the rotation of the centrifugal atomization evaporation assembly 140, the porous media 220 is configured to spray droplets of coating material from the gap 226 of the centrifugal atomization evaporation assembly 140 toward the continuous flexible substrate 108 along a spray path 223a and a spray path 223b. During rotation of the centrifugal atomization evaporation assembly 140, the internal heater 224 and the feed line 228 are stationary. The relative motion between a stationary feed line 228 and the rotating porous media 220 pumps the coating material into the gap 226 while preventing leakage. The groove on the outer diameter of the feed line 228 distributes the coating material down the inner diameter of the porous media 220. The outer diameter of the feed line 228 would be approximately equal to the inner diameter of the porous media 220.

[0051] In some embodiments, the inner tube 222 is stationary. In other embodiments, the inner tube 222 rotates with the porous media 220. In some embodiments, the rotation of the centrifugal atomization evaporator 214 around the feed line 228 may facilitate the metering of the flow of the coating material into the gap 226.

[0052] The coating material droplet size of the centrifugal atomization evaporation assembly 140 is controlled by the outer radius r1 of the porous media 220 and the rotational velocity of porous media 220. The droplet size is defined by Equation 1 (shown below), where d is the droplet size, Q is the feed rate of the coating material, o is the surface tension of the coating material, co is the angular velocity, p is the density of the coating material, and r is the radius of the porous media (e.g., outer radius r1 ). [0053] The porous media 220 is configured to rotate the centrifugal atomization evaporator 214 at an angular velocity of about 10 rad/sec to about 600 rad/sec, with a rotations per minute (RPM) of about 250 RPM to about 500 RPM. The droplet velocity is about 1 m/sec to about 1 .3 m/sec, and the droplet acceleration is about 33.5 m/sec ² and about 68.5 m/sec ² . The coating material is metered into the gap 226 at up to about 500 cc/min. In some embodiments, the metered flow of the coating material is greater than a spray rate of the porous media 220 (e.g., consumption rate of the coating material). The coating material is forced through the pores of the porous media 220 through the centrifugal force of the rotation and through capillary forces. The excess coating material exits the gap 226 via a release channel (not shown) and is collected in the evaporator body 212. The centrifugal atomization evaporation assembly 140 is configured to deposit a coating material layer with a thickness greater than about 1 pm.

[0054] The centrifugal atomization evaporation assembly 140 decreases the heat of the evaporation system 100 by reducing or eliminating the latent heat of vaporization from evaporating the coating material. The centrifugal atomization evaporation assembly 140 produces only the latent heat of fusion from the melting of the coating material in the centrifugal atomization evaporator 214. The reduction in the heat in the evaporation system 100 enables the processing of heat sensitive substrates and reduces the overall thermal budget expended by the coated substrates 108. The reduction of heat also enables faster production, due to a reduction in the need for heat removal from the evaporation system 100.

[0055] Further, the centrifugal atomization evaporation assembly 140 enables deposition control without the use of nozzles. The elimination of nozzles further decreases the heat of the evaporation system 100, as the nozzles are required to be heated to high temperatures to prevent clogging with the coating material. The high temperatures and proximity of the nozzles to the substrates increases the thermal budget expended by the substrate 108, and therefore the removal of the nozzles enables processing of heat sensitive substrates.

[0056] The evaporation system 100 may be housed in a vacuum to prevent the contamination of the coating material during the process. However, while within the vacuum, there is still the potential for the coating material to be contaminated. Such contamination may create oxides and nitrides, which may cause clogging in the pores of the porous media 220. The material return pathway 221 may include one or more filters to capture the contaminated materials. Further, the vacuum may be purged with inert gases, such as argon or other noble gas to create a near inert environment. The centrifugal atomization evaporation assembly 140 may further be ultrasonically vibrated to enable the prevention, reduction, or elimination of the contaminations within the evaporation system 100.

[0057] A vacuum to rotary feedthrough may be used to bring the rotary motion from the motor into the vacuum of the evaporation system 100. The motor is located outside of the vacuum of the evaporation system 100. A first pulley is located on inside the vacuum, and a second pulley is located outside the vacuum. The first pulley and the second pulley are connected by the belt driver. The belt driver may include a material that is not thermally conductive to prevent the motor from overheating.

[0058] In some embodiments, the centrifugal atomization evaporator assembly 140a is replaced with a conventional evaporator. The conventional evaporator is configured to pre-coat the continuous flexible substrate 108 with the coating material. The pre-coat layer may have a thickness less than about 1 pm. By pre-coating the continuous flexible substrate 108, the conventional evaporator may create a coating- philic surface onto which the centrifugal atomization evaporator assemblies 140 can deposit coating material. The creation of the coating-philic pre-coat layer enables a reduction in beading of the coating material and increased uniformity of the deposited film.

[0059] FIG. 3A illustrates a schematic perspective view of a portion of a v-groove porous cylinder 220a. FIG. 3B illustrates a schematic perspective view of a portion of a rectangular groove porous cylinder 220b. FIG. 3C illustrates a schematic perspective view of a portion of a u-groove porous cylinder 220c. FIG. 3D illustrates a schematic perspective view of a portion of a spiral groove porous cylinder 220d. FIG. 3E illustrates a schematic perspective view of a portion of a blind-hole porous cylinder 220e. [0060] The v-groove porous cylinder 220a has a v-shaped groove 238a. The rectangular groove porous cylinder 220b has a rectangular shaped groove 238b. The u-groove porous cylinder 220c has a u-shaped groove 238c. The v-shaped groove 238a, rectangular shaped groove 238b, and the u-shaped groove 238c may be cut linearly along the length of the porous media 220. The spiral groove porous cylinder 220d has a spiral groove 238d cut along the length of the porous media 220. The spiral groove 238d may be a v-shaped groove 238a, a rectangular shaped groove 238b, or a u-shaped groove 238c. The blind-hole porous cylinder 220e includes one or more blind-holes 238e. The one or more blind-holes 238e may be conical, spherical, cylindrical, slots, slots with tapered walls, or other shapes. The pattern of the blind-holes 238e can be spiral, linear, or staggered. The blind-holes 238e may have a depth of about 0.75 mm to about 5.75 mm.

[0061] FIG. 4 illustrates a schematic cross-sectional view of an alternative centrifugal atomization evaporation assembly 440 in accordance with one or more implementations of the present disclosure. The alternative centrifugal atomization evaporation assembly 440 may be used as the centrifugal atomization evaporation assembly 140 in the evaporation system 100.

[0062] The alternative centrifugal atomization evaporation assembly 440 includes a deposition control opening 417. The deposition control opening 417 has a width of about 1 mm to about 75 mm. The evaporator wall 213 includes a top portion 413 which, in part, defines the width of the deposition control opening 417. The deposition rate of the coating material is controlled by the rotations per minute of the centrifugal atomization evaporator 214 and the width of the deposition control opening 417. The droplets of the coating material that spray off of the centrifugal atomization evaporator 214 along spray path 223a and 223b are deposited on the substrate 108.

[0063] In some embodiments, the excess droplets of the coating material are sprayed onto the top portion 413 of the evaporator wall 213. The excess droplets of coating material, in some embodiments, may fall back onto the centrifugal atomization evaporator 214 along spray path 423a. The rotation of the centrifugal atomization evaporator 214 sprays the excess droplets along spray path 423b and spray path 423c. The material collection funnel 219 is configured to collect the excess droplets of coating material and funnel the excess droplets of coating material to the material return pathway 221 . The material return pathway 221 is configured to transport excess droplets of coating material to a coating material supply source 190.

[0064] Figure 5 illustrates a flow chart of a method 500 of coating a substrate 108. The method 500 begins at operation 501 , where a substrate 108 is provided to an evaporation system 100. In various embodiments, the evaporation system 100 includes an unwinding reel 106, a coating drum 110, a winding reel 112, a coating material supply source 190, and a power supply 180. The substrate 108 travels through the evaporation system 100 via the unwinding reel 106, the coating drum 110, and the winding reel 112.

[0065] At operation 502, a coating material is fed into a centrifugal atomization evaporator 214. The coating material is fed to the centrifugal atomization evaporator 214 from the coating material supply source 190. The centrifugal atomization evaporator 214 is disposed within the evaporation system 100. The centrifugal atomization evaporator 214 includes a porous media 220, an inner tube 222, and an internal heater 224. The porous media 220 and the inner tube 222 define a gap 226. The porous media has a porosity of about 2 pm to about 500 pm. The coating material is metered into the gap 226 at up to about 500 cc/min.

[0066] At operation 503, the coating material is heated by the internal heater 224. The internal heater 224 heats the coating material to a temperature of about 150°C to 400°C, such as about 186°C to about 350°C. The internal heater 224 melts the coating material or maintains the coating material in a melted state. The melted coating material is able to transport through the porous media 220 through capillary forces.

[0067] At operation 504, the centrifugal atomization evaporator 214 is rotated to cause the coating material to be sprayed from the centrifugal atomization evaporator 214 toward the substrate 108. The centrifugal atomization evaporator 214 is rotated at an angular velocity of about 10 rad/sec to about 600 rad/sec, with a rotations per minute (RPM) of about 250 to about 500. The rotation of the centrifugal atomization evaporator 214 creates a centrifugal force to enable the transport of the coating material through the porous media 220. In various embodiments, the sprayed droplets of the coating material have a droplet velocity of about 1 m/sec to about 1.3 m/sec, and a droplet acceleration is about 33.5 m/sec ² and about 68.5 m/sec ² .

[0068] At operation 505, the substrate 108 is coated by the sprayed coating material. The thickness of the coating material deposited on the substrate 108 is greater than about 1 pm, such as up to about 20 pm.

[0069] In summary, an evaporation system includes a centrifugal atomization evaporator. The centrifugal atomization evaporator includes a porous media, an inner tube, and an internal heater. The porous media and inner tube define a gap into which a coating material is metered. The internal heater melts the coating material, which is sprayed from the porous media using capillary and centrifugal forces to coat a substrate. The use of the centrifugal atomization evaporator reduces the thermal budget expended by the substrate to be coated, reduces the processing cost in the system, and enables controlled deposition of the coating material.

[0070] According to some implementations, evaporation processes and evaporation apparatus for layer deposition on substrates, for example on flexible substrates, are provided. Thus, flexible substrates can be considered to include among other things films, foils, webs, strips of plastic material, metal, or other materials. Typically, the terms “web,” “foil,” “strip,” “substrate” and the like are used synonymously. According to some implementations, components for evaporation processes, apparatuses for evaporation processes and evaporation processes according to implementations described can be provided for the above-described flexible substrates. However, they can also be provided in conjunction with nonflexible substrates such as glass substrates or the like, which are subject to the reactive deposition process from evaporation sources.

[0071] When introducing elements of the present disclosure or exemplary aspects or implementation(s) thereof, the articles “a,” “an,” “the” and “said” are intended to mean that there are one or more of the elements.

[0072] The terms “comprising,” “including” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. [0073] While the foregoing is directed to implementations of the present disclosure, other and further implementations of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.