SUBSTRATE, CHARGED PARTICLE DEVICE FOR TREATMENT OF A COATING, AND APPARATUS FOR PROCESSING OF A FLEXIBLE

SUBSTRATE

TECHNICAL FIELD

[1] Embodiments of the present disclosure relate to methods, devices and apparatuses for processing of a flexible substrate, particularly treating a coating on a flexible substrate using charged particles. In particular, embodiments of the present disclosure relate to methods, devices and apparatuses for treating a liquid monomer coating on a flexible substrate in vacuum conditions using an electron beam.

BACKGROUND

[2] Processing of flexible substrates, such as plastic films, foils or paper, is in high demand in the packaging industry, semiconductor industries and other industries. For example, processing can include coating a flexible substrate with a desired material for a particular application. For instance, materials used for coating flexible substrates can include polymers, dyes, metals, semiconductors or dielectric materials. Typically, systems performing this task include a process drum for transporting the substrate through a processing region, e.g. in order to coat or print the substrate. Such processing systems are typically referred to as rotary systems or roll-to-roll (R2R) systems.

[3] For obtaining high quality coatings on flexible substrates, there remain several challenges to be mastered. In particular, in coating or printing systems using a liquid coating material, the liquid coating material supplied needs to be accurately and uniformly provided on the flexible substrate. Further, the liquid coating material needs to be uniformly stabilized or cured on the flexible substrate. For curing liquid coating materials on flexible substrates, different types of charged particle sources, e.g. electron sources, can be used. In view of the continuous demand to provide thinner and larger flexible substrates with highly homogenous and thin coatings, improved methods, devices and apparatuses for curing liquid coating materials are of high interest. SUMMARY

[4] In light of the above, a method of treating a coating on a flexible substrate, a charged particle device for treatment of a coating on a flexible substrate, and an apparatus for processing of a flexible substrate according to the independent claims are provided. Further aspects, advantages, and features are apparent from the dependent claims, the description, and the accompanying drawings.

[5] According to an aspect of the present disclosure, a method of treating a coating on a flexible substrate is provided. The method includes providing a first beam of charged particles with a first energy El on the coating, providing a second beam of charged particles with a second energy on the coating, and providing a third beam of charged particles with a third energy E3 on the coating. The third energy E3 is different from at least one of the first energy El and the second energy E2.

[6] According to another aspect of the present disclosure, a charged particle device for treatment of a coating on a flexible substrate is provided. The charged particle device includes a first linear source for providing a first beam of charged particles with a first energy on the coating. Additionally, the charged particle device includes a second linear source for providing a second beam of charged particles with a second energy E2 on the coating. Further, the particle device includes a third linear source for providing a third beam of charged particles with a third energy E3 on the coating. The third energy E3 is different from at least one of the first energy El and the second energy E2.

[7] According to a further aspect of the present disclosure, an apparatus for processing of a flexible substrate is provided. The apparatus includes a processing drum for guiding the flexible substrate. Additionally, the apparatus includes a printing arrangement for printing a coating on the flexible substrate. Further, the apparatus includes a charged particle device for treatment of the coating on the flexible substrate. The charged particle device includes a first linear source for providing a first beam of charged particles with a first energy on the coating. Additionally, the charged particle device includes a second linear source for providing a second beam of charged particles with a second energy E2 on the coating. Further, the particle device includes a third linear source for providing a third beam of charged particles with a third energy E3 on the coating. The third energy E3 is different from at least one of the first energy El and the second energy E2. In particular, the apparatus for processing of a flexible substrate includes a charged particle device according to any embodiments described herein.

[8] According to a yet further aspect of the present disclosure, a method of manufacturing a device including a coated flexible substrate is provided. The method of manufacturing a device includes using a method of treating a coating on a flexible substrate. The method of treating a coating on a flexible substrate includes providing a first beam of charged particles with a first energy El on the coating, providing a second beam of charged particles with a second energy on the coating, and providing a third beam of charged particles with a third energy E3 on the coating The third energy E3 is different from at least one of the first energy El and the second energy E2. Additionally or alternatively, the method of manufacturing a device including a coated flexible substrate includes using a charged particle device for treatment of a coating on a flexible substrate. The charged particle device includes a first linear source for providing a first beam of charged particles with a first energy on the coating. Additionally, the charged particle device includes a second linear source for providing a second beam of charged particles with a second energy E2 on the coating. Further, the particle device includes a third linear source for providing a third beam of charged particles with a third energy E3 on the coating. The third energy E3 is different from at least one of the first energy El and the second energy E2. In particular, the method of manufacturing a device including a coated flexible substrate includes using at least one of the method of treating a coating on a flexible substrate according to any embodiments described herein and the charged particle device according to any embodiments described herein. [9] Embodiments are also directed at apparatuses for carrying out the disclosed methods and include apparatus parts for performing the described method aspect. These method aspects may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, embodiments according to the disclosure are also directed at methods for operating the described apparatus. The methods for operating the described apparatus include method aspects for carrying out every function of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS [10] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following: FIG. 1 shows a schematic representation for illustrating a method of treating a coating on a flexible substrate according to embodiments described herein;

FIGS. 2 to 5 show schematic representations for illustrating a method of treating a coating on a flexible substrate according to further embodiments described herein; FIGS. 6 A and 6B show flowcharts for illustrating a method of treating a coating on a flexible substrate according to embodiments described herein;

FIG. 7 shows a diagram for illustrating an exemplary energy dose distribution in a coating by employing the method of treating a coating according to embodiments described herein; FIG. 8 shows a schematic view of a charged particle device for treatment of a coating on a flexible substrate according to embodiments described herein; FIG. 9 shows a schematic view of a charged particle device for treatment of a coating on a flexible substrate according to further embodiments described herein;

FIG. 10 shows a schematic view of a linear source according to embodiments described herein;

FIG. 11 shows a schematic view of an apparatus for processing of a flexible substrate according to embodiments described herein; and

FIG. 12 shows a flowchart for illustrating a method of manufacturing a device including a coated flexible substrate according to embodiments described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

[11] Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to same components. Only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the disclosure and is not meant as a limitation of the disclosure. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.

[12] With exemplary reference to FIG. 1, a method of treating a coating 11 on a flexible substrate 10 according to the present disclosure is described. According to embodiments which can be combined with other embodiments described herein, the method includes providing a first beam 111 of charged particles with a first energy Ei on the coating 11. Additionally, the method includes providing a second beam 112 of charged particles with a second energy on the coating 11. Further, the method includes providing a third beam 113 of charged particles with a third energy E on the coating 11. The third energy E ₃ is different from at least one of the first energy Ei and the second energy E ₂ . [13] Accordingly, it is to be understood that the energy dose applied to the coating can be adjusted, particularly by selecting the first energy Ei, the second energy E2, and the third energy E . Compared to the state of the art, the method of treating a coating on a flexible substrate as described herein beneficially provides for improved curing of the coating. In particular, by employing the method of treating a coating of the present disclosure, the energy absorption in the coating, e.g. for curing and/or polymerization of the coating, can be optimized. Accordingly, embodiments of the method of treating a coating as described herein provide for improved curing quality, e.g. in terms of curing homogeneity. Further, the method of treating a coating as described herein is particularly well suited for curing and/or polymerizing coatings having a coating thickness of less than 1 pm, particularly less than 0.5 pm, or even less than 0.3 pm. It is to be understood that embodiments of the method of treating a coating as described herein can also be used for curing and/or polymerizing coatings having a coating thickness of more than 1 pm. In particular, it is to be understood that by selecting the proper energies for the respective beams, the curing and/or polymerization efficiency can be optimized for a particular selected coating thickness. Moreover, by employing the method of treating a coating as described herein, the curing speed and/or polymerization speed of coatings can be increased. In other words, compared to the state of the art, embodiments of the method of treating a coating as described herein provide for a reduction of curing time and/or polymerization time. Thus, embodiments of the present disclosure beneficially provide for improved curing and/or polymerization of thin coatings (e.g. coatings with a coating thickness of less than 1 pm, particularly a coating thickness of less than 0.5 pm) while curing time and/or polymerization time can be reduced, such that the overall process costs can be decreased.

[14] As exemplarily indicated by the double sided arrow in FIG. 1, typically the flexible substrate is moved in a transport direction T while treating the coating on the flexible substrate. Accordingly, the method of treating the coating on the flexible substrate may include moving the flexible substrate in a transport direction T. For instance, moving the flexible substrate may include moving the flexible substrate at a speed v _s of 1 m/s < v _s < 15 m/s, particularly 2 m/s < v _s < 10 m/s, more particularly 3 m/s < v _s < 7 m/s, e.g. v _s = 4.5 m/s ± 0.5 m/s or v _s = 6.0 m/s ± 0.5 m/s. According to another example, the speed v _s at which the flexible substrate is moved can be 12 m/s < v _s < 15 m/s. In particular, it is to be understood that by increasing the number of sources for providing beams of charged particles on the coating, the speed for moving the flexible substrate can be increased.

[15] Before various further embodiments of the present disclosure are described in more detail, some aspects with respect to some terms used herein are explained.

[16] In the present disclosure, a“coating” can be understood as a layer or film provided on a substrate as described herein. For instance, the coating can be a liquid coating provided on the substrate. Typically, the coating is a monomer coating, particularly a liquid monomer coating. For instance, the coating can be a liquid acrylic monomer coating. Typically, the coating has a coating thickness T _c of 0.1 pm < T _c < 1.0 pm, particularly 0.1 pm < T _c < 0.7 pm, more particularly 0.1 pm < T _c < 0.5 pm. Alternatively, the coating may have a coating thickness T _c of more than 1.0 pm, e.g. 1.0 pm < T _c < 10 pm.

[17] In the present disclosure, a“flexible substrate” may be characterized in that the substrate is bendable. For example, the flexible substrate may be a foil or a web. In particular, it is to be understood that embodiments as described herein can be utilized for processing any kind of flexible substrates, e.g. for manufacturing coatings or electronic devices on flexible substrates. For example, a substrate as described herein may include materials like PET, HC-PET, PE, PI, PU, OPP, CPP, PLA, PHA, TaC, one or more metals, paper, combinations thereof, and already coated substrates like Hard Coated PET (e.g. HC-PET, HC-TAC) and the like. Typically, the flexible substrate is a polymeric flexible substrate. The flexible substrate may have a substrate thickness T _s of T _s < 150 pm, particularly 5 pm < T _s < 150 pm, more particularly 5 pm < T _s < 20 pm, e.g. T _s = 12 pm ± 1 pm.

[18] In the present disclosure,“charged particles” can be understood as particles with an electric charge. For instance, charged particles can be ions or electrons. According to an example, the charged particles are electrons.

[19] As exemplarily illustrated in FIGS. 1 and 2, according to embodiments which can be combined with other embodiments described herein, the method of treating the coating 11 on the flexible substrate 10 further includes at least partially superimposing the first beam 111, the second beam 112 and the third beam 113. For instance, as exemplarily shown in FIG. 1, the first beam 111 with the first energy Ei can be at least partially superimposed with the second beam 112 with the second energy E2. Further, FIG. 1 shows that the second beam 112 with the second energy E2 can be at least partially superimposed with the third beam 113 with the third energy E . As exemplarily shown in FIG. 1, the individual beams (i.e. the first beam 111, the second beam 112 and the third beam 113) of charge particles may have a cone-like shape. For instance, the cone-like shape can be substantially symmetric with respect to a main direction of the respective beam. In FIGS. 1 and 2, the first main direction 11M of the first beam 111, the second main direction 12M of the second beam 112, and the third main direction 13M of the third beam 113 are indicated. Alternatively, the first beam 111, the second beam 112 and the third beam 113 can be separated. In other words, the first beam 111, the second beam 112 and the third beam 113 may not be superimposed.

[20] As exemplarily shown in FIG. 2, the first beam 111 with the first energy Ei can be at least partially superimposed with the second beam 112 with the second energy E ₂ as well as with the third beam 113 with the third energy E ₃ . Accordingly, the second beam 112 with the second energy E can be at least partially superimposed with the first beam 111 with the first energy Ei as well as with the third beam 113 with the third energy E ₃ . The third beam 113 with the third energy E ₃ can be at least partially superimposed with the first beam 111 with the first energy Ei as well as with the second beam 112 with the second energy E . In particular, as exemplarily shown in FIG. 2, the first beam 111, the second beam 112 and the third beam 113 may be inclined towards each other, such that the first beam 111, the second beam 112 and the third beam 113 are at least partially superimposed with each other.

[21] As exemplarily shown in FIG. 2, typically the first beam 111 has a first main direction 11M, the second beam 112 has a second main direction 12M, and the third beam 113 has a third main direction 13M. Further, as shown in FIG. 2, a first inclination angle (X12 may be provided between the first main direction 11M and the second main direction 12M. The first inclination angle (X12 can be 2° < (X12 £ 60°, particularly 5° < cq ₂ £ 45°, more particularly 10° < a £ 30°. A second inclination angle a ₂₃ may be provided between the second main direction 12M and the third main direction 13M. The second inclination angle (X ₂₃ can be 2° < <¾ < 60°, particularly 5° < a ₂₃ < 45°, more particularly 10° < a ₂₃ < 30°. According to embodiments which can be combined with other embodiments described herein, the absolute value of the first inclination angle ai ₂ corresponds to the absolute value of the second inclination angle a _23.

[22] According to embodiments which can be combined with other embodiments described herein, the first energy Ei is 3 keV < Ei < 5 keV, particularly Ei = 4 keV ± 0.5 keV. The second energy E ₂ can be 3 keV < E ₂ < 5 keV, particularly E ₂ = 4 keV ± 0.5 keV. The third energy E can be 4 keV < E ₂ < 6 keV, particularly E = 5 keV ± 0.5 keV. It is to be understood that selecting the first energy El, the second energy E2 and the third energy E ₃ as specified herein can be beneficial for providing improved curing and/or polymerization of thin coatings (e.g. coatings with a coating thickness of less than 1 pm, particularly a coating thickness of equal to or less than 0.5 pm), e.g. with respect to a reduction of curing/ polymerization time, curing/ polymerization homogeneity and curing/ polymerization quality. It is to be understood that the values for the first energy Ei, the second energy E ₂ , and the third energy E can be adjusted according to the material employed for the coating and/or according to the thickness of the coating.

[23] With exemplary reference to FIG. 3, according to embodiments which can be combined with other embodiments described herein, moving the flexible substrate in the transport direction T may include using a processing drum 310. The processing drum 310 is configured for guiding the flexible substrate. In the present disclosure, a “processing drum” can be understood as a drum or a roller having a substrate support surface for contacting the flexible substrate. In particular, the processing drum can be rotatable about a rotation axis 311 in a rotation direction R, as exemplarily indicated in FIG. 3. Typically, the processing drum includes a substrate guiding region. 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 may be adapted to be (at least partly) in contact with the flexible substrate during guiding of the flexible substrate. [24] With exemplarily reference to FIGS. 4 and 5, according to embodiments which can be combined with other embodiments described herein, the method of treating the coating 11 on the flexible substrate 10 further includes providing a fourth beam 114 of charged particles with a fourth energy E ₄ on the coating 11. The fourth energy E ₄ is different from at least one of the first energy Ei, the second energy E ₂ and the third energy E ₃ . Accordingly, the curing/ polymerization quality of the coating can further be improved.

[25] According to embodiments which can be combined with other embodiments described herein, the method of treating the coating 11 on the flexible substrate 10 further includes at least partially superimposing the fourth beam 114 with at least one of the first beam 111, the second beam 112 and the third beam 113. For instance, as exemplarily shown in FIG. 4, the fourth beam 114 with the fourth energy E ₄ may be at least partially superimposed with the third beam 113 of third energy E ₃ . Although not explicitly shown, it is to be understood that the fourth beam 114 may additionally or alternatively be superimposed with the first beam 111 and/or the second beam 112. Alternatively, the fourth beam 114 may be separated from the first beam 111, the second beam 112 and the third beam 113. In other words, the fourth beam 114 may not be superimposed with one or more of the first beam 111, the second beam 112 and the third beam 113.

[26] According to embodiments which can be combined with other embodiments described herein, the fourth energy E ₄ is 6.5 keV < E4 < 8.5 keV, particularly E ₄ = 7.5 keV ± 0.5 keV.

[27] As exemplarily shown in FIG. 5, the first beam 111 with the first energy Ei can be at least partially superimposed with the second beam 112 with the second energy E ₂ as well as with the third beam 113 with the third energy E ₃ and the fourth beam 114 with the fourth energy E ₄ . Accordingly, the second beam 112 with the second energy E can be at least partially superimposed with the first beam 111 with the first energy Ei as well as with the third beam 113 with the third energy E and the fourth beam 114 with the fourth energy E ₄ . The third beam 113 with the third energy E ₃ can be at least partially superimposed with the first beam 111 with the first energy Ei as well as with the second beam 112 with the second energy E ₂ and the fourth beam 114 with the fourth energy E ₄ . In particular, as exemplarily shown in FIG. 5, the first beam 111, the second beam 112, the third beam 113 and the fourth beam 114 may be inclined towards each other, such that the first beam 111, the second beam 112, the third beam 113 and the fourth beam 114 can be at least partially superimposed with each other.

[28] As exemplarily shown in FIG. 5, typically the fourth beam 114 has a fourth main direction 14M. Further, as shown in FIG. 5, a third inclination angle 0 ₃₄ may be provided between the third main direction 13M and the fourth main direction 14M. The third inclination angle (X34 can be 2° < 0. ₃₄ < 60°, particularly 5° < (X34 < 45°, more particularly 10° < (X34 < 30°. According to embodiments which can be combined with other embodiments described herein, the absolute value of the third inclination angle (X34 corresponds to the absolute value of the first inclination angle (X12 and/or to the absolute value of the second inclination angle (X23.

[29] FIGS. 6A and 6B show flowcharts for illustrating a method 160 of treating a coating on a flexible substrate according to embodiments of the present disclosure. Block 161 in FIGS. 6 A and 6B represents providing a first beam 111 of charged particles with a first energy El on the coating 11, as described herein. Block 162 in FIGS. 6 A and 6B represents providing a second beam 112 of charged particles with a second energy E2 on the coating 11, as described herein. Block 163 in FIGS. 6 A and 6B represents providing a third beam 113 of charged particles with a third energy E3 on the coating 11, as described herein. Block 164 in FIG. 6B represents providing a fourth beam 114 of charged particles with a fourth energy E4 on the coating 11, as described herein. It is to be understood that typically the flexible substrate is moved in a transport direction while the first beam 111 and/or the second beam 112 and/or the third beam 113 and or the fourth beam 114 are provided on the coating 11 on the flexible substrate 10.

[30] It is to be understood that embodiments of the present disclosure are not limited to three or four sources for providing respective beams of charged particles with respective energies on the coating. The embodiments described herein are for explanation of the concept of the method of treating a coating on a flexible substrate, the charged particle device for treatment of a coating on a flexible substrate, and the apparatus for processing of a flexible substrate as described herein. Accordingly, it is to be understood that more than four sources (i.e. a multitude of more than four sources) for providing respective beams of charged particles with a respective energies on the coating can be implemented.

[31] FIG. 7 shows a diagram for illustrating an exemplary energy dose distribution in a coating by employing a method of treating a coating according to embodiments described herein. In particular, FIG. 7 shows the normalized energy dose as a function of penetration depth x. In FIG. 7, an example with a coating thickness T _c of T _c =500 nm is shown. It is to be understood that at x = 0 nm, the beams of charged particles hit the surface of the coating. Further, it is to be understood that after having passed the coating, the beams of charged particles enter the flexible substrate on which the coating is provided. Accordingly, in the example shown in FIG. 7, the energy dose in the flexible substrate is the energy dose depicted at x > 500 nm.

[32] In the example shown in FIG. 7, the first curve Cl represents the energy dose distribution in the coating and the substrate resulting by conducting the method as described herein with a first energy Ec of E _| = 4 keV, a second energy E ₂ of E ₂ = 4 keV, a third energy E of E = 5 keV, and a fourth energy E ₄ of E ₄ = 7.5 keV, when the flexible substrate is moved at a speed v _s = 6.0 m/s. For comparison, the second curve C ₂ represents the energy dose distribution in the coating and the substrate resulting providing a first energy E ₁ a second energy E ₂ , a third energy E ₃ and a fourth energy E ₄ of Ei = E ₂ = E = E4 = 7.5 keV, when the flexible substrate is moved at a speed v _s = 6.0 m/s.

[33] As can be seen from FIG. 7, the variation of the electron energies changes the penetration depth of the electrons into the material to be cured and hence can be optimized to deposit the energy precisely where the curing is supposed to happen. The area under the respective curves for 0 nm < x < 500 nm reflects the dose, i.e. the amount of energy deposited in the mass of the coating, and is higher for the first curve Ci compared to the second curve C ₂ . It is to be understood that FIG. 7 only shows a non-limiting example for illustrating the advantage of the embodiments of the present disclosure. [34] Generally, it has been found that by providing at least three beams of charged particles in which at least one of the at least three beams has a different energy than the at least other two beams, the energy dose absorption in the coating can be increased, such that curing and/or polymerization of the coating can be improved.

[35] With exemplary reference to FIG. 8, a charged particle device 100 for treatment of a coating on a flexible substrate according to the present disclosure is described. It is to be understood that the method of treating a coating according to embodiments described herein can be conducted by using the charged particle device as described herein. According to embodiments which can be combined with other embodiments described herein, the charged particle device 100 includes a first linear source 110 for providing a first beam 111 of charged particles with a first energy El on the coating 11. Additionally, the charged particle device 100 includes a second linear source 120 for providing a second beam 112 of charged particles with a second energy E2 on the coating 11. Further, the charged particle device 100 includes a third linear source 130 for providing a third beam 113 of charged particles with a third energy E3 on the coating 11. The third energy E3 is different from at least one of the first energy El and the second energy E2. Accordingly, it is to be understood that each of the first linear source 110, the second linear source 120 and the third linear source 130 is a source for forming a beam of charged particles for the treatment of the coating on the substrate moving along a transport direction T. Typically, a“linear source” as described herein is an electron source.

[36] According to embodiments herein, the charged particle device may be used in polymerization reactions that may, for example, form polymer films on flexible substrates. In particular, the charged particle device can be used for polymerization of a monomer coating as described herein.

[37] According to embodiments which can be combined with other embodiments described herein, the first linear source 110 has a first slit opening 115 extending along a length L of the first linear source 110. The second linear source 120 has a second slit opening 125 extending along a length L of the second linear source 120. The third linear source 130 has a third slit opening 135 extending along a length L of the third linear source 130. As exemplarily shown in FIG. 8, typically, the length L of the first linear source is substantially equal to the length L of the second linear source and/or the length of the third linear source.

[38] According to embodiments which can be combined with other embodiments described herein, the first slit opening 115, the second slit opening 125, and the third slit opening 135 are substantially parallel. As exemplarily indicated in FIGS. 8 and 9, typically a slit opening as described herein has a width W. Further, from FIGS. 8 and 9 it is to be understood that the length of a slit opening as described herein is at least 80% of the length L of a linear source as described herein, particularly at least 90% of the length L of a linear source as described herein. [39] Typically, the aspect ratio AR of the width of the slit opening as described herein to the length of the slit opening as described herein is AR < 1/5, particularly AR < 1/10, more particularly AR < 1/20.

[40] According to embodiments which can be combined with other embodiments described herein, the first slit opening 115, the second slit opening 125, and the third slit opening 135 are inclined towards each other. In particular, it is to be understood that the first linear source 110, the second linear source 120 and the third linear source can be arranged such that the first slit opening 115 provides for a first main direction 11M, the second slit opening 125 provides for second main direction 12M, and the third slit opening 135 provides for a third main direction 13M, as exemplarily described with reference to FIG. 2.

[41] With exemplary reference to FIG. 9, according to embodiments which can be combined with other embodiments described herein, the charged particle device includes a fourth linear source 140 for providing a fourth beam 114 of charged particles with a fourth energy E4 on the coating 11. The fourth energy E4 is different from at least one of the first energy El, the second energy E2 and the third energy E3. As exemplarily shown in FIG. 9, the fourth linear source 140 has a fourth slit opening 145 extending along a length of the fourth linear source 140. Typically, the fourth slit opening 145 is substantially parallel to the first slit opening 115, the second slit opening 125, and the third slit opening 135. [42] Further, as exemplarily shown in FIG. 9, the fourth slit opening 145 can be inclined to at least one of the first slit opening 115, the second slit opening 125, and the third slit opening 135. In particular, it is to be understood that the fourth linear source 140 can be arranged such that the fourth slit opening 145 provides for a fourth main direction 14M, as exemplarily described with reference to FIG. 5.

[43] With reference to FIG. 10, a linear source 200 according to embodiments of the present disclosure is described. It is to be understood that features described with reference to the linear source shown in FIG. 10 may apply to the first linear source 110 and/or the second linear source 120 and/or the third linear source 130 and/or the and/or the fourth linear source 140, as described herein.

[44] In particular, FIG. 10 shows a section of a linear source 200 for providing a beam of charged particles for treatment of a coating on a flexible substrate treatment. The section shown in FIG. 10 is in a cross-section along a direction, which is perpendicular to a longitudinal axis of the linear source. In FIG. 10, the longitudinal axis of the linear source may be defined as the direction into and out of the page.

[45] According to embodiments, which can be combined with other embodiments described herein, the linear source 200 may include a housing 210. The housing 210 may provide a first electrode. According to embodiments herein, the first electrode may be the anode, which may optionally be grounded. The housing 210 may have a back wall 212 and a front wall 214. The front wall 214 and the back wall 212 of the housing 210 may be connected to each other via a first side wall 211 and a second side wall 213. According to embodiments herein, the first side wall 211 and the second side wall 213 may be arranged parallel to each other.

[46] In embodiments described herein, the front wall 214 of the housing 210 includes an extraction aperture, which may also be referred to as slit opening 216. The slit opening 216 may be adapted for enabling a beam of charged particles passing from the inside of the housing to the outside of the housing. According to embodiments herein, the slit opening 216 may divide the front wall 214 of the housing 210 into a first front wall portion 215 and a second front wall portion 217. The first front wall portion 215 and the second front wall portion 217 may be symmetric with respect to the line of symmetry 201 defined as a plane dividing the linear source 200 into equal halves. For instance, the line of symmetry 201 may be perpendicular to the back wall 212 of the housing 210 of the linear source 200. The slit opening 216 typically extends along the length direction of the linear source 200. In the exemplary embodiment shown in Fig. 10, the length direction of the linear source 200 may be described as the direction into or out of the page.

[47] According to embodiments, which can be combined with other embodiments described herein, the front wall 214 of the housing 210 including the first front wall portion 215 and/or the second front wall portion 217 may be configured to be arranged towards a second electrode 220. For instance, the first front wall portion 215 and/or the second front wall portion 217 may be inclined towards the second electrode 220, particularly with an inclination having a first end of the front wall portion adjacent to the slit opening closer to the cathode as compared to an opposing end of the respective front wall portion.

[48] Typically, during operation of the linear source 200, plasma may be formed within the housing 210, in the space 202 between the second electrode 220 and the front wall 214 of the housing 210. Further, end walls (not shown in the figures) may cover either end of the housing of the linear source 200. Further, the linear source 200 may include at least one connection element selected from the group consisting of: a connection element for electrical power, a connection element for a gas, and a connection element for a cooling fluid.

[49] The second electrode 220 may be arranged within the housing 210. The second electrode may be the cathode and may include materials with a low sputter rate but a high secondary electron co-efficient such as, for example, graphite and carbon fibre composites (CFC). In embodiments herein, the second electrode may extend in a direction parallel to the length direction of the linear source.

[50] According to embodiments, which can be combined with other embodiments described herein, the second electrode 220 has at least a first side 222 facing the slit opening 216 of the housing 210 (i.e. the first side of the second electrode may also be referred to as a front side of the second electrode). The first side 222 may be curved. The curvature of the first side 222 may increase the extraction efficiency of the linear source 200. For example, the first side 222 may be curved away from the slit opening 216 and be referred to as a concave first side, which may increase the surface area of the second electrode 220 and which may help to focus the beam of charged particles emitted from the second electrode towards the slit opening 216. The second electrode 220 may also have a second side 224 facing the back wall 212 of the housing 210 (i.e. the second side of the second electrode may also be referred to as a rear side of the second electrode).

[51] According to embodiments, which may be combined with other embodiments described herein, the second electrode 220 has one or more beam shaping extensions 225. The one or more beam shaping extensions 225 protrude from the second electrode 220 in a direction towards the front wall 214 of the housing 210. Accordingly, the second electrode including the beam shaping protrusions may have a U-shape or C-shape form. Generally, the one or more beam shaping extensions may extend in a direction parallel to the longitudinal direction of the second electrode 220. Not limited to any one particular embodiment described herein, the second electrode may include a single beam shaping extension, two beam shaping extensions or a plurality of beam shaping extensions.

[52] According to embodiments herein, the one or more beam shaping extensions 225 may be configured to guide a charged particle beam emanating from the second electrode 220 through the slit opening 216 in order to further increase the extraction efficiency of the linear source 200. In particular, the one or more beam shaping extensions may be adapted such that during operation, electric field lines are formed between the one or more beam shaping extensions 225 and the housing 210 of the linear source 200 guide electrons, which are generated by the interaction of ions from the plasma with the second electrode 220, towards the slit opening 216. An exemplary trajectory of the beam of charged particles including the Coulomb repulsion of electrons by space charge is illustrated in FIG. 10 (see reference number 205).

[53] For example, as shown in FIG. 10, the second electrode 220 of the linear source 200 may include a first beam shaping extension and a second beam shaping extension. The first beam shaping extension and the second beam shaping extension may be arranged at opposite ends of the second electrode 220. According to embodiments herein, the first beam shaping extension and/or the second beam shaping extension may be integrally formed with the second electrode or be manufactured separately and connected to the second electrode during assembly of the second electrode.

[54] Generally, the one or more beam shaping extensions 225 of the second electrode 220 may be arranged to be spaced away from the first side wall 211 and the second side wall 213 of the housing 210 respectively. The second electrode 220 may also be spaced away from the back wall 212 of the housing 210. Accordingly, a dark space may be formed between the beam shaping extensions 225 and the interior surfaces of the housing 210.

[55] According to embodiments herein, the dark space may prevent plasma generation, which may increase the energy efficiency of the linear source 200 due to reducing the formation of plasma in unwanted spaces within the housing 210 of the linear source 200. A further advantageous effect of the dark space, which contributes to the overall improved energy efficiency of the linear source 200, may be to prevent energy loss due to excessive heating of the housing 210.

[56] According to embodiments herein, the linear source 200 may include a cooling system 250 for cooling the housing 210, which may further improve the energy efficiency of the linear source 200. For instance, the cooling system 250 can include at least one passageway to accommodate a cooling fluid. The cooling system 250 may be arranged to cool the back wall 212 of the housing 210. Not limited to any particular embodiment described herein, the cooling system may further be configured to cool at least one of the first side wall 211, second side wall 213 and front wall 214 of the housing 210.

[57] With exemplary reference to FIG. 11, an apparatus 300 for processing of a flexible substrate 10 according to the present disclosure is described. According to embodiments which can be combined with other embodiments described herein, the apparatus 300 includes a processing drum 310 for guiding the flexible substrate. Additionally, the apparatus 300 includes a printing arrangement 320 for printing a coating on the flexible substrate. Further, the apparatus 300 includes a charged particle device 100 for treatment of the coating 11 on the flexible substrate 10. The charged particle device 100 is a charged particle device 100 according to any embodiments described herein.

[58] With exemplary reference to FIG. 11, the printing arrangement 320 may include a supply device 321 for supplying a liquid coating material. For instance, the supply device 321 can be a monomer reservoir. Further, the printing arrangement 320 may include a first roller 322 (e.g. an anilox roller) and a second roller 324 (e.g. a transfer roller). In particular, the first roller 322 may be arranged parallel to the processing drum 310 and the second roller 324. Between the transfer roller and the processing drum 310, the flexible substrate may be transported during processing, e.g. coating or printing of the flexible substrate. Accordingly, it is to be understood that the liquid coating material can be applied to the surface of the first roller 322, e.g. the surface of an anilox roller, from the reservoir while the surface of the first roller 322 passes through the reservoir. Further, as exemplarily shown in FIG. 11, typically the printing arrangement 320 includes a doctor blade assembly 323 having at least one elongated doctor blade extending in a parallel direction to the rotation axis of the first roller 322.

[59] With exemplary reference to the flowchart shown in FIG. 12, a method 400 of manufacturing a device including a coated flexible substrate according to the present disclosure is described. The method 400 of manufacturing a device including a coated flexible substrate includes using the method of treating a coating 11 on a flexible substrate 10 according to any embodiments described herein (represented by block 410 in FIG. 12). Additionally or alternatively, the method 400 of manufacturing a device including a coated flexible substrate includes using a charged particle device 100 according to any embodiments described herein (represented by block 420 in FIG. 12).

[60] Accordingly, embodiments of the present disclosure beneficially provide for improved curing and/or polymerization of a coating. In particular, embodiments of the present disclosure provide for an optimized energy absorption in the coating, e.g. for curing and/or polymerization of the coating, such that curing quality can be improved, e.g. in terms of curing homogeneity. Further, embodiments of the present disclosure are particularly well suited for curing and/or polymerizing coatings having a coating thickness of less than 1 pm, more particularly less than 0.5 pm. Moreover, by employing embodiments of the present disclosure, the curing speed and/or polymerization speed of coatings can be increased, such that beneficially a reduction of curing time and/or polymerization time can be provided. Accordingly, beneficially the overall process costs can be decreased.

[61] This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the described subject-matter, including making and using any apparatus or system and performing any incorporated methods. While various specific embodiments have been disclosed in the foregoing, mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope is defined by the claims, and other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

[62] While the foregoing is directed to embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope is determined by the claims that follow.