ROLLER DEVICE FOR GUIDING A FLEXIBLE SUBSTRATE, USE OF A ROLLER DEVICE FOR CONVEYING A FLEXIBLE SUBSTRATE, VACUUM PROCESSING APPARATUS AND METHOD FOR PROCESSING A FLEXIBLE SUBSTRATE - Patent application

Abstract

A roller device (100) for guiding a flexible substrate (10) is described. The roller device (100) includes a support surface (110) for contacting the flexible substrate (10), the support surface (110) having a coating (120) including an electronegative polymer. Additionally, a vacuum processing apparatus for processing flexible substrates including the roller device (100) and a method for processing flexible substrates in a vacuum processing apparatus are described. [Selected Figure] Figure 1

Description

[Technical field]

[0001] The present disclosure relates to rollers for guiding a flexible substrate.Furthermore, the present disclosure relates to an apparatus and method for flexible substrate processing, specifically for coating a flexible substrate with thin layers using roll-to-roll processing.Specifically, the present disclosure relates to rollers utilized for transporting a flexible substrate in an apparatus and method for coating a flexible substrate with a stack of layers, for example, for thin-film solar cell production, thin-film battery production, and flexible display production. [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. In particular, roll-to-roll (R2R) processing of flexible substrates is of high interest due to its high throughput at low cost. In particular, roll-to-roll deposition systems are of high interest in the manufacturing of thin-film batteries, the display industry, and the photovoltaic (PV) industry. For example, the increasing demand for flexible touch panel elements, flexible displays, and flexible PV modules has resulted in an increased demand for the deposition of suitable layers on R2R coaters.

[0003] Processing can involve coating the flexible substrate with materials (e.g., metals, semiconductors, and dielectric materials), etching, and other processing operations performed on the substrate for the corresponding application. For example, coating processes (e.g., CVD or PVD processes, particularly sputtering processes) can be used to deposit thin layers on the flexible substrate. Systems for performing such operations generally include a coating drum (e.g., a cylindrical roller) coupled to a processing system with a roller assembly for transporting the flexible substrate.

[0004] To achieve high quality coatings on flexible substrates, various challenges related to the transportation of the flexible substrate must be overcome. For example, achieving proper substrate tension and good substrate-to-roller contact while processing a moving flexible substrate under vacuum conditions remains difficult.

[0005] Thus, there is a continuing need to improve the transport of flexible substrates in roll-to-roll processing systems, particularly for coating flexible substrates with higher quality layers or layer stacks having improved uniformity, improved product life, and fewer defects per surface area. Summary of the Invention

[0006] In light of the above, there is provided a roller device for guiding a flexible substrate, a use of the roller device for transporting a flexible substrate, a vacuum processing apparatus for processing a flexible substrate, and a method for processing a flexible substrate in a vacuum processing apparatus according to the independent claims. Further aspects, advantages and features are apparent from the dependent claims, the description and the accompanying drawings.

[0007] According to one aspect of the present disclosure, there is provided a roller device for guiding a flexible substrate, the roller device including a support surface for contacting the flexible substrate, the support surface having a coating including an electronegative polymer.

[0008] According to a further aspect of the present disclosure, there is provided a use of a roller device for transporting a flexible substrate in a vacuum processing apparatus, the roller device including a support surface for contacting the flexible substrate, the support surface having a coating including an electronegative polymer.

[0009] According to another aspect of the present disclosure, a vacuum processing apparatus for processing a flexible substrate is provided. The vacuum processing apparatus includes a first spool chamber housing a storage spool for supplying a flexible substrate. The vacuum processing apparatus further includes a processing chamber disposed downstream from the first spool chamber. The processing chamber includes a plurality of processing units including at least one deposition unit. The processing chamber further includes a roller device for guiding the flexible substrate past the plurality of processing units. The roller device includes a support surface for contacting the flexible substrate. The support surface has a coating including an electronegative polymer. The vacuum processing apparatus further includes a second spool chamber disposed downstream from the processing chamber. The second spool chamber houses a take-up spool for taking up the flexible substrate after processing.

[0010] According to a further aspect of the present disclosure, there is provided a method of processing a flexible substrate in a vacuum processing apparatus. The method includes feeding a flexible substrate from a storage spool disposed in a first spooling chamber. The method further includes processing the flexible substrate while guiding the flexible substrate by a roller device disposed in the processing chamber. The roller device includes a support surface for contacting the flexible substrate. The support surface has a coating including an electronegative polymer. The method further includes winding the flexible substrate after processing onto a take-up spool disposed in a second spooling chamber.

[0011] The embodiments are also directed to apparatus for carrying out the disclosed methods, including apparatus parts for performing each described method aspect. These method aspects may be implemented using hardware components, a computer programmed by appropriate software, any combination of the two, or in any other manner. Additionally, embodiments of the present disclosure are also directed to methods of operating the described apparatus. Methods for operating the described apparatus include method aspects for performing any function of the apparatus. [Brief description of the drawings]

[0012] So that the above-mentioned features of the present disclosure can be understood in detail, a more particular description of the disclosure briefly outlined above can be had by reference to the embodiments. The accompanying drawings relate to embodiments of the present disclosure and are described in the following description. [Figure 1] 1 shows a schematic diagram of a roller device according to embodiments described herein. [Diagram 2] 1 shows a schematic perspective view of a roller device according to a further embodiment described herein; [Diagram 3] 1 shows a schematic diagram of a vacuum processing apparatus according to embodiments described herein. [Figure 4] 1 shows a schematic diagram of a vacuum processing apparatus according to a further embodiment described herein; [Figure 5A] FIG. 1 shows a schematic side view of a vacuum processing apparatus having a set of evaporation crucibles. [Figure 5B] 5B shows a schematic bottom view of the vacuum processing apparatus of FIG. 5A. [Figure 6A-6B] 1 shows a flow diagram illustrating a method for processing a flexible substrate according to an embodiment described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Reference will now be made in detail to various embodiments of the present disclosure. One or more examples of these embodiments are illustrated in the drawings. In the following description of the drawings, like reference numerals represent like components. With respect to the individual embodiments, only the differences are described. While each example is provided as an illustration of the present disclosure, it is not intended to limit the disclosure. Moreover, features illustrated and described as part of one embodiment may be used on or in conjunction with other embodiments, resulting in still further embodiments. It is intended that the present description include such modifications and variations.

[0014] 1, there is shown a roller device 100 for guiding a flexible substrate 10 in accordance with the present disclosure. According to an embodiment, which may be combined with any other embodiment described herein, the roller device 100 includes a support surface 110 for contacting the flexible substrate 10. The support surface 110 has a coating 120 that includes an electronegative polymer.

[0015] Providing the roller device with a coating including an electronegative polymer beneficially provides improved contact between the flexible substrate and the roller device during transport of the flexible substrate. Thus, the roller device embodiments described herein are improved compared to conventional rollers used to guide flexible substrates, particularly in roll-to-roll vacuum processing equipment. More specifically, with the roller device described herein, a substantially constant and homogenous contact force can be achieved between the flexible substrate and the roller device, which can result in improved clamping or adhesion of the flexible substrate to the roller device. The contact force can also be referred to as a clamping force. Furthermore, utilizing a roller device with a coating described herein can improve heat transfer from the flexible substrate to the roller device compared to the prior art. This can be advantageous for processing heat-sensitive flexible substrates, particularly thin polymeric flexible substrates having a substrate width W of 0.3 m≦W≦8 m. This improved heat transfer results from the fact that during guiding of the flexible substrate in the roller device of the present disclosure, direct contact between the substrate and the coated support surface can be achieved over a substantially complete contact area, i.e., areas with gaps (down to the microscale) between the flexible substrate and the coated support surface can be reduced or substantially eliminated.

[0016] Furthermore, it is noted that, in the state of the art, the substrate tension is usually increased to improve the contact between the substrate and the substrate transport rollers, but this may cause some problems when a thin flexible substrate (e.g., a flexible substrate having a substrate thickness ST of 20 μm≦ST≦1 mm) is used. It is therefore necessary to increase the effective contact force or clamping force between the flexible substrate and the rollers with increasing substrate width to compensate for the decrease in effective substrate stiffness for thinner substrates.

[0017] Thus, the embodiments of the roller device described herein are advantageously well suited for guiding polymer flexible substrates having a substrate width W of 0.3 m≦W≦8 m and a substrate thickness ST of 20 μm≦ST≦1 mm.

[0018] Additionally, other conventional means for improving contact between the flexible substrate and the transport or guide rollers (e.g., application of static charge to the substrate and / or the transport / guide rollers) can be reduced or even eliminated. In this regard, it is noted that applying static charge to the substrate (e.g., by using a scalable linear electron beam source) and / or to the transport / guide rollers (e.g., by applying a DC voltage to the transport / guide rollers) can cause damage to the flexible substrate and / or roller surface, for example, due to arcing during operation. Beneficially, therefore, the roller device of the present disclosure can substantially reduce or even eliminate problems associated with conventional means for improving contact between the flexible substrate and the transport rollers.

[0019] Before describing various further embodiments of the present disclosure in more detail, some aspects related to some of the terms used herein are explained.

[0020] In the present disclosure, a "roller device" can be understood to be a drum or roller having a substrate support surface for contacting a flexible substrate. In particular, the roller device can be rotatable about a rotation axis and can include a substrate guiding region. Typically, the substrate guiding region is a curved substrate support surface (e.g., a cylindrically symmetric surface) of the roller device. The curved substrate support surface of the roller device can be adapted to contact (at least partially) the flexible substrate while guiding the flexible substrate. The substrate guiding region can be defined as the angular range of the roller device where the substrate contacts the curved substrate surface while guiding the substrate, and can correspond to the enlacement angle of the roller device. In some embodiments, the enlacement angle of the roller device can be 120° or more, in particular 180° or more, or even 270° or more.

[0021] In the present disclosure, a "flexible substrate" can be understood to be a substrate that can be bent. For example, a "flexible substrate" can be a "foil" or a "web". In the present disclosure, the terms "flexible substrate" and "substrate" can be used synonymously. For example, the flexible substrates described herein can include materials such as PET, HC-PET, PE, PI, PU, ​​TaC, OPP, BOOP, CPP, one or more metals, paper, combinations thereof, and coated substrates such as hard-coated PET (e.g., HC-PET, HC-TaC), and the like. In some embodiments, the flexible substrate is a COP substrate with index-matched (IM) layers on both sides. For example, the thickness of the substrate can be 1 μm or more and 200 μm or less. More specifically, the thickness of the substrate can be selected from a range having a lower limit of 8 μm and an upper limit of 25 μm, for example, for food packaging applications.

[0022] In the present disclosure, the expression "support surface for contacting a flexible substrate" can be understood to be an outer surface of a roller device configured to contact a flexible substrate during guidance or transport of the flexible substrate. Typically, the support surface is a curved outer surface, in particular a cylindrical outer surface, of the roller device.

[0023] In the present disclosure, the expression "support surface having a coating" can be understood as meaning that the support surface of the roller device comprises a coating, i.e. that the support surface is coated. In particular, the coating comprises an electronegative polymer. An "electronegative polymer" can be understood as a polymer having electronegative properties. Usually, the complete support surface is provided with the coating. In particular, the coating has a certain thickness (for example, a thickness T selected from the range 2.5 μm≦T≦15 μm).

[0024] According to some embodiments, which can be combined with other embodiments described herein, the coating 120 has triboelectric properties. In other words, the electronegative polymer can be configured to generate electrostatic charges by frictional contact with the flexible substrate. In particular, the electronegative polymer (e.g., fluoropolymer) can be configured to generate a mirror charge on the flexible substrate surface during induction by the triboelectric effect. The triboelectric effect (also called frictional charging) is a type of contact electrification in which one material becomes charged after frictional contact with another material. In other words, the triboelectric effect can be described as the transfer of charge (electrons) from one material to another after frictional or sliding contact. The total charge transfer between the two materials is determined by the difference in charge affinity between the two contacting material surfaces.

[0025] For example, the substrate materials described herein have a charge affinity CA of -90 nC / J < CA < -40 nC / J. For example, PET has a charge affinity CA of CA ≈ -40 nC / J, BOOP has a charge affinity CA of CA ≈ -85 nC / J, and LDEP, HDPE, and PP have a charge affinity CA of CA ≈ -90 nC / J. Coatings comprising the electronegative polymers described herein, in particular coatings comprising or consisting of fluoropolymers, in particular coatings comprising or consisting of PTFE and / or PFA, have a charge affinity CA of CA ≈ -190 nC / J.

[0026] Thus, advantageously, the coating provided on the support surface of the roller device described herein ensures that the coated roller device is negatively charged compared to the substrate even in the absence of an externally applied electric field. Thus, according to an embodiment that can be combined with other embodiments herein, it should be understood that the coating on the support surface of the roller device can be configured to provide a charge affinity difference ΔCA to the flexible substrate induced by the roller device. In particular, the charge affinity difference ΔCA between the coating and the substrate can be 50 nC / J≦ΔCA≦200 nC / J, in particular 100 nC / J≦ΔCA≦150 nC / J.

[0027] As outlined above, in the roller device embodiments described herein, a coating of an electronegative polymer provided on the support surface of the roller device may be configured to provide contact charging with the flexible substrate during guidance of the flexible substrate. Typically, the flexible substrate is guided by rotating the roller device 100 about the axis of rotation 111 of the roller device, as exemplarily shown by the arrow in FIG. 1. For example, the roller device may be actively driven. In other words, a drive may be applied to rotate the roller device.

[0028] Thus, by providing a coating comprising an electronegative polymer on the support surface of the roller device, configured to generate a mirror charge on the flexible substrate surface in contact with the roll device during substrate guidance, an improvement in the adhesion of the flexible substrate to the roller device is beneficially provided. In other words, by providing a coating having triboelectric properties on the support surface of the roller device, a charge transfer between the coating and the flexible substrate can be beneficially provided, so that a constant and homogeneous contact force (also called pinning or clamping force) between the flexible substrate and the roller device can be ensured. Furthermore, by utilizing the triboelectric effect, slippage between the flexible substrate and the coating provided on the support surface of the roller device is beneficially reduced.

[0029] According to some embodiments, which can be combined with other embodiments described herein, the electronegative polymer can be dielectric. In particular, the electronegative polymer can be an electrically insulating material, which can be polarized. For example, the electronegative polymer can be a fluoropolymer, in particular an elastomeric fluoropolymer, including, for example, perfluoroalkoxy polymer (PFA) and / or polytetrafluoroethylene (PTFE). In particular, the fluoropolymer can be made of PFA or PTFE. Coatings that include or consist of fluoropolymers (e.g., PFA or PTFE) beneficially provide coatings with very high dielectric breakdown strength. Furthermore, coatings that include or consist of fluoropolymers (e.g., PFA or PTFE) beneficially provide low coefficients of friction, in particular, ultra-low coefficients of friction. Thus, beneficially, a low wear rate of the coating, for example comparable to steel, is provided, ensuring the life of the coating. In other words, fluoropolymer coatings provided with a fluorinated polymer coating surface beneficially provide excellent low friction performance levels that reduce effective coating wear.

[0030] According to some embodiments, which may be combined with other embodiments described herein, the coating 120 may have a coefficient of friction μ of μ≦0.1, particularly μ≦0.05. More specifically, the non-lubricated fluoropolymer coefficient of friction μ may be μ≦0.1, particularly μ≦0.05. It is noted that local wear from the coating asperities can result in highly hydrophobic hydrodynamic boundary lubrication, beneficially further reducing the coefficient of friction by a factor F of about F=10. Thus, beneficially, an effective coating material wear rate close to the intrinsic wear rate level of steel can be achieved.

[0031] For example, according to some embodiments, which may be combined with other embodiments described herein, the coating 120 has a surface roughness of 0.4×10 -7 MPa -1 ≦k a ≦2.0×10 -6 Wear rate constant k in MPa-1 a In other words, the coating may have a -7 MPa -1 ≦k a ≦2.0×10 -6 MPa -1 The wear rate constant k is selected from the range a The wear rate constant k a is the dimensionless wear rate constant k divided by the hardness [MPa], i.e., k a [MPa -1 ]=k / hardness [MPa].

[0032] According to some embodiments, which may be combined with other embodiments described herein, the coating 120 may have a thickness T in the range of 2.5 μm≦T≦15 μm. Providing a coating with a thickness T selected from the range of 2.5 μm≦T≦15 μm may be beneficial to ensure sufficient capacitance to ensure sufficient pinning force between the flexible substrate and the coated support surface of the roller device.

[0033] According to some embodiments, which may be combined with other embodiments described herein, the coating 120 has a breakdown field strength BFS of 2.0 MV / cm≦BFS≦30 MV / cm. For example, a coating of PFA with a thickness T of T=5 μm has a BFS of 2.0 MV / cm when subjected to an electric field of 300 V. A coating of PTFE with a thickness T of T=10 μm has a BFS of 24 MV / cm when subjected to an electric field of 300 V.

[0034] 2, according to some embodiments, which may be combined with other embodiments described herein, the roller device 100 is cylindrical and has a length L, where 0.5 m≦L≦8.5 m. Furthermore, the roller device 100 may have a diameter D, where 1.0 m≦D≦3.0 m. Thus, advantageously, the roller device is configured to guide and transport flexible substrates having large widths.

[0035] According to some embodiments, which can be combined with other embodiments described herein, the roller device can have one or more E-chuck devices (not explicitly shown). The E-chuck device can be understood as a device configured to provide an electrostatic charge for holding the substrate by electrostatic force. In particular, the one or more E-chuck devices can provide an attractive force for holding the flexible substrate and / or holding the web in contact with the curved surface of the roller device. Thus, the constant and homogeneous contact force between the flexible substrate and the roller device can be further improved.

[0036] In view of the above, it should be appreciated that according to a further aspect of the present disclosure there is provided the use of a roller device according to any embodiment described herein for transporting a flexible substrate within a vacuum processing apparatus, in particular the vacuum processing apparatus according to the embodiments described with reference to Figures 3 and 4.

[0037] With exemplary reference to FIG. 3, a vacuum processing apparatus 200 according to the present disclosure is described. According to an embodiment that can be combined with any other embodiment described herein, the vacuum processing apparatus 200 includes a first spool chamber 210 that accommodates a storage spool 212 for supplying the flexible substrate 10. Furthermore, the vacuum processing apparatus 200 includes a processing chamber 220 disposed downstream from the first spool chamber 210. The processing chamber 220 includes a plurality of processing units 221. The plurality of processing units 221 includes at least one deposition unit. For example, the plurality of processing units may be arranged in a circumferential direction around the roller device 100, as shown diagrammatically in FIG. 3 and FIG. 4. As the roller device 100 rotates, the flexible substrate is guided past the processing units facing the curved substrate support surface of the roller device, so that the surface of the flexible substrate may be processed while passing through the processing units at a predetermined speed. For example, the plurality of processing units may include one or more units selected from the group consisting of a deposition unit, an etching unit, and a heating unit. The deposition unit of the vacuum processing apparatus described herein can be a sputter deposition unit (eg, an AC (alternating current) sputter source or a DC (direct current) sputter source, a CVD deposition unit, a PECVD deposition unit, or a PVD deposition unit).

[0038] Further, the processing chamber 220 includes a roller device 100 for guiding the flexible substrate past the multiple processing units 221. The roller device 100 includes a support surface 110 for contacting the flexible substrate 10. The support surface 110 has a coating 120 including an electronegative polymer. In particular, the roller device is a roller device according to any embodiment described herein. Further, the vacuum processing apparatus 200 includes a second spool chamber 250 disposed downstream from the processing chamber 220. The second spool chamber 250 houses a take-up spool 252 for taking up the flexible substrate 10 after processing.

[0039] Thus, the embodiments of the vacuum processing apparatus described herein are improved over conventional vacuum processing apparatus. In particular, by providing a vacuum processing apparatus with a roller device as described herein, improved guidance and transport of the flexible substrate is advantageously achieved. More particularly, the roller device described herein can provide a substantially constant and homogenous contact force between the flexible substrate and the roller device, improving the clamping or adhesion of the flexible substrate to the roller device, thereby improving the guidance and transport of the flexible substrate. Thus, advantageously, a substantially wrinkle-free transport of the flexible substrate can be ensured, resulting in a higher quality processing result (e.g., a higher quality coating on the flexible substrate).

[0040] In the present disclosure, a "vacuum processing apparatus" can be understood as an apparatus configured to process a substrate, in particular a flexible substrate as described herein. In particular, the vacuum processing apparatus can be a roll-to-roll (R2R) processing apparatus configured to coat a flexible substrate with a stack of layers. Typically, the vacuum processing apparatus has at least one vacuum chamber, in particular a vacuum processing chamber. Furthermore, the processing apparatus can be configured for substrate lengths of 500 m or more, 1000 m or more, or even several km. The width of the substrate can be 300 mm or more, in particular 500 mm or more, more particularly 1 m or more. Furthermore, the substrate width can be 8 m or less, in particular 6 m or less.

[0041] In the present disclosure, a "processing chamber" can be understood to be a chamber having at least one deposition unit for depositing a material on a substrate. A processing chamber may therefore also be called a deposition chamber. The term "vacuum" as used herein can be understood to mean a technical vacuum, e.g. having a vacuum pressure of less than 10 mbar. Typically, the pressure in the vacuum chamber described herein is less than 10 -5 mbar to about 10 -8 mbar, more typically 10 -5 mbar to 10-7 mbar, and even more typically about 10 -6 mbar to about 10 -7 It may be between 100 and 200 mbar.

[0042] The terms "upstream from" and "downstream from" used herein may refer to the location of each chamber or component relative to another chamber or component along the substrate transport path. For example, in operation, a substrate is guided from a first spool chamber 210 through a processing chamber 220 and then guided along the substrate transport path via a roller assembly to a second spool chamber 250. Thus, the processing chamber 220 is located downstream from the first spool chamber 210, and the first spool chamber 210 is located upstream from the processing chamber 220. In operation, the substrate is first guided or transported past a first roller or first component and then guided or transported past a second roller or second component. The second roller or second component is located downstream from the first roller or first component.

[0043] As illustrated in FIGS. 3 and 4, the first spool chamber 210 is typically configured to house a storage spool 212, which may be provided with a flexible substrate 10 wound thereon. In operation, the flexible substrate 10 may be fed from the storage spool 212 and transported along a substrate transport path (illustrated by the arrows in FIGS. 3 and 4) from the first spool chamber 210 toward the processing chamber 220. The term "storage spool" as used herein may be understood to be a roll in which the flexible substrate to be coated is housed. Thus, the term "wind-up spool" as used herein may be understood to be a roll adapted to receive the coated flexible substrate. Furthermore, the term "storage spool" may also be referred to as a "supply roll" and the term "wind-up spool" may also be referred to as a "take-up roll."

[0044] In the present disclosure, a "processing unit" can be understood to be a unit or device configured to process a flexible substrate as described herein. For example, the processing unit can be a deposition unit. Specifically, the deposition unit can be a sputter deposition unit (e.g., an AC sputter source or a DC sputter source). However, the processing apparatus described herein is not limited to sputter deposition, and other deposition units can be used additionally or alternatively. For example, in some implementations, a CVD deposition unit, an evaporative deposition unit, a PECVD deposition unit, or other deposition units can be utilized. Thus, it should be understood that a deposition unit (e.g., a plasma deposition source) can be adapted to deposit thin films on a flexible substrate to form, for example, a flexible display device, a touch screen device component, or other electronic or optical devices.

[0045] According to some embodiments, which can be combined with other embodiments described herein, the roller device 100 of the vacuum processing apparatus is a processing drum. In the present disclosure, a "processing drum" can be understood to be a drum or roller having a substrate support surface for contacting a flexible substrate during processing. In particular, the processing drum can be rotatable about a rotation axis 111 and can include a substrate guiding region. Typically, the substrate guiding region is a curved substrate support surface (e.g., a cylindrically symmetric surface) of the processing drum. The curved substrate support surface of the processing drum can be adapted to (at least partially) contact a flexible substrate during operation of the processing apparatus described herein.

[0046] Specifically, and with exemplary reference to Figure 4, the roller device 100 can be connected to a device 240 for applying an electrical potential to a processing drum. The processing drum is the roller device 100 according to any embodiment described herein.

[0047] In the present disclosure, a "device for applying a potential to a processing drum" can be understood as a device configured to apply a potential to the processing drum, in particular to the substrate support surface of the processing drum. In particular, the device for applying a potential can be configured to provide a medium frequency (MF) potential. For example, the medium frequency (MF) potential can be from 1 kHz to 100 kHz. In the present disclosure, a "device for applying a potential" can also be referred to as a "potential application device". Applying a MF potential to the processing drum has the advantage that charging up of the substrate, in particular of the layer deposited on the substrate, can be substantially avoided or even eliminated. Thus, a layer of higher quality (e.g., more uniform, less defects, etc.) can be deposited on the substrate. Thus, providing a potential application apparatus is beneficial to further improve the constant and homogeneous contact force between the flexible substrate and the roller device, which can result in improved and substantially wrinkle-free flexible substrate transport during substrate processing.

[0048] With exemplarily reference to Figures 3 and 4, it should be understood that typically the vacuum processing apparatus 200 is configured to guide the flexible substrate 10 from the first spool chamber 210 to the second spool chamber 250 along the substrate transport path. The substrate transport path can pass through the processing chamber 220. For example, the flexible substrate can be coated with a stack of layers in a deposition chamber. Furthermore, as illustrated in Figures 3 and 4, a roller assembly with multiple rolls or rollers can be provided to transport the substrate along the substrate transport path. Figures 3 and 4 show a roller assembly with four rollers. It should be understood that according to different configurations, the roller assembly can include more than four rollers, in particular more than ten rollers, arranged between the storage spool and the take-up spool.

[0049] 3 and 4, according to some embodiments herein, which may be combined with any other embodiments described herein, the roller assemblies may be configured to transport the flexible substrate along a partially convex and partially concave substrate transport path from a first spool chamber to a second spool chamber. In other words, the substrate transport path may curve partially to the right and partially to the left, such that some of the guide rollers contact a first major surface of the flexible substrate and some of the guide rollers contact a second major surface of the flexible substrate opposite the first major surface.

[0050] For example, the first guide roller 207 in Figure 4 contacts the second major surface of the flexible substrate, and the flexible substrate is bent to the left while being guided by the first guide roller 207 (the "convex" portion of the substrate transport path). The second guide roller 208 in Figure 4 contacts the first major surface of the flexible substrate, and the flexible substrate is bent to the right while being guided by the second guide roller 208 (the "concave" portion of the substrate transport path).

[0051] In some embodiments, one or more rollers (e.g., guide rollers) of the roller assembly may be disposed between the storage spool 212 and the processing drum (i.e., the roller device 100) and / or downstream of the processing drum. For example, in the embodiment shown in FIG. 3, two guide rollers are provided between the storage spool 212 and the processing drum, at least one guide roller may be disposed in the first spool chamber, and at least one guide roller may be disposed in the processing chamber upstream from the processing drum. In some embodiments, three, four, five or more, particularly eight or more guide rollers are provided between the storage spool and the processing drum. The guide rollers may be active or passive rollers.

[0052] As used herein, an "active" roller or roll can be understood as a roller that is provided with a drive or motor to actively move or rotate the respective roller. For example, an active roller can be adjusted to provide a predetermined torque or a predetermined rotation speed. Typically, the storage spool 212 and the take-up spool 252 can be provided as active rollers. Furthermore, an active roller can be configured as a substrate tension roller configured to tension the substrate at a predetermined tension during operation. A "passive" roller can be understood as a roller or roll that is not provided with a drive to actively move or rotate the passive roller. A passive roller can rotate due to frictional forces of the flexible substrate that may be in direct contact with the outer roller surface during operation.

[0053] 4, one or more guide rollers 213 may be disposed downstream from the processing drum (i.e., roller device 100) and upstream from the second spooling chamber 250. For example, to smoothly guide the flexible substrate 10 onto the take-up spool 252, at least one guide roller may be disposed in the processing chamber 220 downstream from the processing drum for guiding the flexible substrate 10 toward the second spooling chamber 250 disposed downstream from the processing chamber 220, or at least one guide roller may be disposed in the second spooling chamber 250 upstream from the processing drum for guiding the flexible substrate in a substantially tangential direction relative to the substrate support surface of the processing drum.

[0054] According to some embodiments, which may be combined with other embodiments described herein, one or more guide rollers of a roller assembly may include a coating comprising an electronegative polymer, as exemplified for the roller devices according to any embodiment described herein.

[0055] According to some embodiments, some or all of the chambers of vacuum processing apparatus 200 may be configured as evacuable vacuum chambers. For example, the vacuum processing apparatus may include components and devices that allow for the creation or maintenance of a vacuum in first spool chamber 210 and / or processing chamber 220 and / or second spool chamber 250. In particular, the vacuum processing apparatus may include vacuum pumps, exhaust ducts, vacuum seals, etc. for creating or maintaining a vacuum in first spool chamber 210 and / or processing chamber 220 and / or second spool chamber 250.

[0056] 4, according to an embodiment that may be combined with other embodiments described herein, a sealing device 205 may be provided between adjacent chambers, for example, between the first spool chamber 210 and the processing chamber 220, and / or between the processing chamber 220 and the second spool chamber 250. Beneficially, therefore, the take-up chambers (i.e., the first spool chamber 210 and the second spool chamber 250) may be independently evacuated or evacuated, and in particular independently evacuated or evacuated from the processing chambers. The sealing device 205 may include an inflatable seal configured to press the substrate against a flat sealing surface.

[0057] As illustrated in FIG. 4, typically, a processing drum (i.e., a roller device as described herein) is configured to guide the flexible substrate 10 past a number of deposition units (e.g., past a first deposition unit 221A, a second deposition unit 221B, and a third deposition unit 221C). As shown in FIG. 4, the individual deposition units may be provided in separate compartments. The separate compartments allow a modular combination of several different subsequent deposition processes (e.g., CVD, PECVD, and / or PVD) and ensure very good gas isolation between the various subsequent deposition processes. Thus, depending on the selected sequence of the deposition units, a variety of different stacked layers can be deposited on the flexible substrate.

[0058] FIG. 5A shows a schematic side view of a processing apparatus according to an alternative configuration, and FIG. 5B shows a schematic bottom view of the processing apparatus shown in FIG. 5A. In particular, referring to FIG. 5A and FIG. 5B by way of example, the multiple processing units may include or be configured as a set of evaporation crucibles 230 aligned along a line 222 extending parallel to the rotation axis 111 of the roller device 100. Thus, the vacuum processing apparatus may be an evaporation apparatus for depositing evaporation material on the substrate 10. For example, the set of evaporation crucibles 230 shown in FIG. 5A includes crucibles 211 to 217. As illustrated in FIG. 5B, the evaporation crucibles are typically configured to generate a cloud 255 of evaporation material to be deposited on the flexible substrate 10. As shown in FIG. 5B, the multiple processing units may be arranged in a direction spanning the substrate width W.

[0059] An "evaporation crucible" can be understood as a reservoir for a material to be evaporated by heating the evaporation crucible. More specifically, the evaporation crucible can be equipped with a material supply that supplies the material to be evaporated to the crucible. For example, the material to be evaporated may be supplied to the evaporation crucible in the form of a wire that can be melted by the evaporation crucible. According to some embodiments, the evaporation crucible can be configured as an evaporator boat, especially when the material to be evaporated is supplied in the form of a wire. Thus, the set of evaporation crucibles described herein can be a set of evaporator boats. The material to be evaporated can be a metal (e.g. aluminum, copper or any other metal). The processing device exemplarily described with reference to Figures 5A and 5B is particularly well suited for coating substrates used in the packaging industry, in particular the food packaging industry.

[0060] With exemplarily reference to the flow diagram shown in FIG. 6A, a method 300 of processing a flexible substrate 10 in a vacuum processing apparatus 200 according to the present disclosure is described. According to an embodiment that can be combined with any other embodiment described herein, the method includes unloading the flexible substrate 10 from a storage spool 212 disposed in a first spooling chamber 210 (represented by block 310 in FIG. 6A). The method further includes processing the flexible substrate 10 while guiding the flexible substrate by a roller device 100 disposed in a processing chamber 220 (represented by block 320 in FIG. 6A). The roller device 100 includes a support surface 110 for contacting the flexible substrate 10. The support surface 110 has a coating 120 including an electronegative polymer. In particular, the roller device 100 can be a roller device according to any embodiment described herein. The method further includes winding the flexible substrate 10 after processing onto a take-up spool 252 disposed in a second spooling chamber 250 (represented by block 330 in FIG. 6A).

[0061] 6B, according to some embodiments that can be combined with other embodiments described herein, the method further includes applying a potential to the roller device 100 (represented by block 340 in FIG. 6B). For example, applying a potential to the roller device (block 340) can include applying an intermediate frequency potential having a frequency of 1 kHz to 100 kHz. In particular, applying a potential to the roller device 100 typically includes using a device 240 for applying a potential, for example as described with reference to FIG. 4.

[0062] It should further be understood that the method of processing a flexible substrate in a vacuum processing apparatus may be performed, for example, by using the vacuum processing apparatus 200 according to any embodiment described herein with reference to Figures 3 and 4.

[0063] In view of the above, it should be appreciated that, in comparison to the prior art, the embodiments described herein provide improved flexible substrate transport in roll-to-roll processing equipment such that thinner and wider flexible substrates can be processed and processing results can be improved.

[0064] While the forgoing description is directed to exemplary embodiments, other and further embodiments may be devised without departing from the basic scope of the disclosure, the scope of which is defined by the appended claims.

Claims

1. 1. Use of a roller device (100) for transporting a flexible substrate (10) in a vacuum processing apparatus (200), the roller device comprising a support surface (110) for contacting the flexible substrate (10), the support surface (110) having a coating (120) comprising an electronegative polymer, the coating (120) and the flexible substrate (10) configured to provide a charge affinity difference ΔCA of 50 nC / J≦ΔCA≦200 nC / J.

2. A vacuum processing apparatus (200) for processing a flexible substrate (10), comprising: a first spool chamber (210) for housing a storage spool (212) for supplying the flexible substrate (10); a processing chamber (220) disposed downstream from the first spool chamber (210), the processing chamber (220) comprising a plurality of processing units (221) with at least one deposition unit, and a roller device (100) for guiding the flexible substrate past the plurality of processing units (221), the roller device comprising a support surface (110) for contacting the flexible substrate (10), the support surface (110) having a coating (120) comprising an electronegative polymer, the coating (120) and the flexible substrate (10) configured to provide a charge affinity difference ΔCA of 50 nC / J≦ΔCA≦200 nC / J; and a second spool chamber (250) disposed downstream from said processing chamber (220) for accommodating a take-up spool (252) for taking up said flexible substrate (10) after processing; A vacuum processing apparatus (200) comprising:

3. 3. The vacuum processing apparatus (200) of claim 2, wherein the roller device (100) is a processing drum, the processing drum being connected to a device (240) for applying an electrical potential to the processing drum.

4. A method (300) for processing a flexible substrate (10) in a vacuum processing apparatus (200), comprising: unloading the flexible substrate (10) from a storage spool (212) disposed within a first spool chamber (210); processing the flexible substrate (10) while guiding the flexible substrate by a roller device (100) disposed within a processing chamber (220), the roller device (100) comprising a support surface (110) for contacting the flexible substrate (10), the support surface (110) having a coating (120) comprising an electronegative polymer, the coating (120) and the flexible substrate (10) configured to provide a charge affinity difference ΔCA of 50 nC / J≦ΔCA≦200 nC / J; After processing, winding the flexible substrate onto a take-up spool (252) located within a second spool chamber (250). The method includes:

5. The method of claim 4, further comprising applying (340) an electrical potential to the roller device (100).

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