Fluid application method for improved roll-to-roll pattern formation

Abstract

Methods, apparatus and systems are disclosed by which patterned layers can be formed in a roll-to-roll process using a variable and programmable means for applying liquids and solutions used in the patterning process.

Claims

1. A continuous roll-to-roll method for forming a desired pattern on a flexible substrate of desired length, the method comprising: a. providing a rotary-shaped template surface comprising a 3D relief pattern in a roll-to-roll embossing process; b. providing a substrate having a surface for receiving a complementary relief pattern complementary to that of the 3D relief pattern; c. providing a fluid applicator operative to apply a fluid selectively in relationship to the 3D relief pattern of the template; d. contacting together the substrate and the rotary-shaped template with the intervening selectively applied fluid; e. solidifying the fluid wherein the complementary relief pattern is formed; and f. by use of a continuous roll-to-roll process, removing the substrate containing the complementary relief pattern from the rotary template surface; wherein the fluid is a polymer-softening solvent or an etchant.

2. The method of claim 1 in which the fluid is a radiation-curable monomer.

3. A continuous roll-to-roll method for forming a desired pattern on a flexible substrate of desired length, the method comprising: a. providing a rotary-shaped template surface comprising a 3D relief pattern in a roll-to-roll embossing process; b. providing a substrate having a surface for receiving a complementary relief pattern complementary to that of the 3D relief pattern; c. providing a fluid applicator operative to apply a fluid selectively in relationship to the 3D relief pattern of the template; d. contacting together the substrate and the rotary-shaped template with the intervening selectively applied fluid; e. solidifying the fluid, wherein the complementary relief pattern is formed; and f. by use of a continuous roll-to-roll process, removing the substrate containing the complementary relief pattern from the rotary template surface; wherein the fluid applicator comprises multiple rows of applicator arrays, and wherein rows of applicator arrays dispense different fluids.

4. The method of claim 3 in which the fluid applicator comprises an ink jet head array.

5. The method of claim 3 in which the fluids differ in physico-chemical properties.

6. The method of claim 5 in which the differing property is viscosity.

7. The method of claim 3 in which the fluids are different solvents.

8. The method of claim 1 in which the dispensers are controlled by computer.

9. The method of claim 8 in which the fluid is dispensed in a pre-defined pattern.

10. The method of claim 9 in which the pattern is a specific relationship to the template pattern.

11. The method of claim 8 in which electronic and/or optical means are used to synchronize the fluid application.

12. The method of claim 4 in which the ink jet nozzles can dispense variable fluid volumes.

13. The method of claim 9 in which deposition at template seams or defects is avoided.

14. A continuous roll-to-roll method for forming a desired pattern on a flexible substrate of desired length, the method comprising: a. providing a rotary-shaped template surface comprising a 3D relief pattern in a roll-to-roll embossing process; b. providing a substrate having a surface for receiving a complementary relief pattern complementary to that of the 3D relief pattern; c. providing a fluid applicator operative to apply a fluid selectively in relationship to the 3D relief pattern of the template; d. contacting together the substrate and the rotary-shaped template with the intervening selectively applied fluid; e. solidifying the fluid, wherein the complementary relief pattern is formed; and f. by use of a continuous roll-to-roll process, removing the substrate containing the complementary relief pattern from the rotary template surface; wherein the 3D relief pattern of the rotary template is formed by an opaque metal layer on a transparent cylindrical substrate in the form of a rotary photomask.

15. The method of claim 14 in which radiation exposure through the rotary photomask is used to solidify the applied fluid.

16. The method of claim 15 in which the fluid is a radiation-curable monomer.

17. The method of claim 1 in which the fluid is applied to the substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 depicts multiple-nozzle fluid application to moving web.

(2) FIG. 2 depicts multiple-nozzle fluid application to moving web with array rotation for higher resolution.

(3) FIG. 3 depicts multiple-nozzle fluid application onto moving web using multiple arrays.

(4) FIG. 4 depicts multiple-nozzle arrays with different fluids.

(5) FIG. 5 depicts synchronized patterning of substrate using multiple-nozzle array.

(6) FIG. 6 depicts synchronized patterning of substrate using multiple-nozzle arrays and multiple fluids.

(7) FIG. 7 shows a method for encoding patterns into variable data.

(8) FIG. 8 depicts the synchronized patterning of substrate using multiple-nozzle arrays and multiple fluids.

(9) FIG. 9 is a schematic depiction of the selective application of fluid to patterning drum.

(10) FIG. 10 is a schematic depiction of the selective application of fluid to substrate.

DETAILED DESCRIPTION

(11) As used herein, the term substrate is used to denote a support film that carries the replicated pattern, in some cases as formed directly into the surface of the film itself or as an applied layer over the substrate. In roll-to-roll manufacturing terminology, the substrate is also referred to in the art as a web, base, or foil (the last term often encompassing flexible metal substrates as well). The process of replicating a pattern is variously referred to as stamping, molding, embossing, imprinting, forming, where the prefixes micro- and nano- are often added to denote a general size range of the replicated features. The term nanoimprint lithography has more recently been used to describe the replication of nanoscale features. In continuous roll-to-roll replication, the element that forms the pattern replica is variously described as a rotary stamp or tool, embossing drum, imprinting cylinder, printing sleeve, belt, etc.

(12) FIG. 1 illustrates a normal incidence view of a flexible substrate prior to coming into contact with the rotary patterning template (not shown). Substrate 100 travels under dispenser array 101, after which dispensed fluid 102 can be seen deposited onto the substrate. The electronic controls for the dispense is not shown. Illustrated here is a uniform application of fluid from each dispenser orifice at low linear nozzle density, but current technology allows tens to hundreds of nozzles per linear inch to be utilized.

(13) In FIG. 2 is illustrated the ability to achieve higher density with a dispenser array. In this case the same dispenser shown in FIG. 1 (101) is rotated around its normal axis (201) such that the nozzles are closer together, resulting in the output 202 to have higher spatial density. Vibrating the array in the cross-web direction 203 can also be used to increase the spacing density. It should be noted that although a linear array of dispenser nozzles is shown for simplicity, a 2D array can also be used for even greater density.

(14) Shown in FIG. 3 is a fluid application configuration using multiple linear dispensers. Here substrate 100 is fed under head array 301, consisting of individual head arrays 303, 304, 305. The output from all heads is shown as 302. Note that each of 303, 304, 305 can be individually rotated (not shown) for different linear densities (they can be space apart in the web travel direction to accommodate this rotation). Note dispense flow is simplified to more clearly show the fluid path from each nozzle.

(15) The use of different fluids being dispensed from different heads is illustrated in FIG. 4, where the input substrate 100 is fed under dispensers 401, with individual arrays 403, 404, 405 allowing various possible printing configurations. For example, multiple nozzles at the same cross-web position can be fired together to give higher fluid coverage (406). Other nozzles can be fired to dispense only a certain fluid in a certain area (407), or even no fluid (408). In this sketch, heavier line weights are used to denote different physical fluid properties, such as viscosity or surface tension.

(16) The use of image-wise fluid dispensing is illustrated in FIG. 5. Here, head array 301 is used to print a specific pattern 502 comprising various pattern elements (lines, squares, hexagons, etc.). In this case the dispensed pattern corresponds to the template pattern on the rotary tool and is designed to apply the pattern replication fluid only where required.

(17) Synchronizing the image-wise fluid output to the pattern of the drum template is shown schematically in FIG. 6. Fluid pattern 602 corresponds to template pattern 608 on rotary drum 613. In order to assure that both patterns align (i.e., fluid pattern 614 with template pattern 615), an opto-electric sensor 609 is used to determine the position of a particular template pattern element (or alignment mark) and fire the dispenser pattern at the correct time such that the fluid pattern will align with the template pattern when it arrives at the template 608 on the drum 613. The detection electronics 610 drives the print trigger 611 at the appropriate time for the patterns to be synchronized.

(18) FIG. 7 illustrates a variation of that illustrated in FIG. 6. Here the template pattern 708 is mounted on rotary drum 613 and consists of an optical element, such as security hologram or optical variable device (OVD). Head array 301 dispenses a radiation curable monomer fluid onto substrate 100 in a specific pattern 714. Exposure of the fluid while in contact with the template pattern (not shown) results in the cured polymer 715 containing the template pattern. When necessary to synchronize the printed fluid with the pattern, sensor 709 sends the position signal the processing unit 610, which in turn triggers the fluid applicator 611.

(19) FIG. 8 illustrates the use of different fluids to optimize the fidelity of the replicated pattern. An array of dispensing nozzles 401 produces on substrate 100 a fluid pattern 802 consisting of fluid 806, 807, 808, each having different physical or chemical characteristics (e.g., viscosity) and each being dispensed by a different array (403, 404, 405). Each fluid element is optimized for its corresponding pattern element. For example, 806 might be a higher viscosity radiation curable monomer for a large-volume template element, whereas 808 might be a lower viscosity monomer required for very small pattern elements. As with the process shown in FIG. 6, the variable-material pattern is synchronized with the rotary template pattern.

(20) A side view sketch of a roll-to-roll process of the present invention, where the fluid is dispensed directly onto the template instead of the substrate, is given in FIG. 9. Substrate 100 is transported into nip 917, where it comes into contact with fluid 902, in this case a radiation curable monomer, which was applied using array dispenser 401 onto the rotary template 613. Internal radiation source 916 causes solidification of the applied monomer, and the formed pattern is continuously removed as the substrate with patterned layer 918 is transported to the rewind station (web transport, control, and synchronization are not shown). Note that for internal radiation curing, drum template 916 must be transparent to the radiation required for solidification of the monomer fluid. The rotary template 613 can also be a rotary metal-on-glass photomask, where in this case the openings in the mask allow radiation to pass and expose the monomer (photoresist) fluid applied by the dispenser. For small features, the photomask process generally does not achieve the small feature sizes that the molding process can achieve due to light scattering, diffraction and other optical issues.

(21) The process in FIG. 10 is similar to that in FIG. 9, except in this case fluid 802 is applied to incoming substrate 100 rather that to the template pattern 613, and exposure source 916 causes fluid 802 to solidify, after which time it is separated from the rotary template 613 as patterned substrate 918.