TW201307453A - Selectively etching of a polymer matrix on PET - Google Patents

Abstract

The present invention relates to a method for selectively etching and patterning with high resolution of flexible polymer matrices, which may comprise Ag nano tubes.

Description

Method for selectively etching a polymer matrix on polyethylene terephthalate (PET)

The present invention relates to a method of selectively etching and high resolution patterned polymer matrix comprising a silver nanotube.

Micro/nano wires with integrated ohmic contacts have been prepared from batch wafers by metal deposition and patterning, high temperature annealing, and anisotropic chemical etching. Today, a wide range of applications in displays, sensors, medical devices, and other systems are of interest for electrical devices that are formed from high quality single crystal semiconductor nano and microstructures on large area mechanically flexible plastic substrates. A number of methods have been demonstrated to transfer high quality semiconductor materials to plastic substrates.

Conventional photolithography methods, while having many uses for forming the structure and composition of surface features, are expensive and require specialized equipment. In addition, photolithography methods make it difficult to apply patterns to very large and/or non-rigid surfaces such as textiles, paper, and plastics.

In laser-assisted etching methods, the laser beam scans all of the etched pattern dots on the substrate, which, in addition to high accuracy, requires considerable adjustment work and is very time consuming.

On the other hand, however, it is possible to provide an efficient device that can be directly constructed on a wide range of abnormal device substrates, such as plastic or paper. In particular, the transfer of an organized array of such wires to a plastic substrate at low temperatures produces a high quality bendable metal semiconductor field effect transistor; for example, an electrical device is prepared for polyethylene terephthalate [PET] {Y.Sun et al; Applied Physics Letters, 87, 083501 (2005)}. The latter method uses high-quality bulk GaAs wafers as the starting material, the "top-down" assembly process to form micro/nano wires and the transfer technology uses elastic stamps to combine the well-ordered arrays and plastics of these wires. Substrate. In this method, the pattern of photoresist lines is defined at the top of the metal strip. A plurality of openings exist between adjacent metal strips and the openings allow the etchant to diffuse to the GaAs surface to anisotropically etch GaAs. The anisotropic etching produces reverse mesas and undercuts along the surface of the GaAs, causing the assembly of the GaAs lines to be released from the mother wafer.

This apparatus and method for patterning the surface is well known and includes photolithography and soft contact printing techniques such as "microcontact printing" as disclosed in U.S. Patent 5,512,131.

Surface characterization can be made with soft lithography to have lateral dimensions as small as 40 nm, but limits the range of surface features that can be formed using these techniques.

This means that according to the current state of the art, the polymer-based substrate can be selectively etched directly by laser support or by wet chemical or by dry etching after masking. Into any desired structure.

In another method, a paste is used to form a variable surface feature with a complex configuration. The paste is typically applied to the surface by screen printing, spraying, ink jet printing or syringe deposition. However, the lateral dimensions of the surface features produced by these methods are also limited. In particular, it has been found that it is difficult to achieve a lateral dimension of less than 100 μm. In particular, if the pattern that must be patterned or structured is composed of different materials and is uneven, it will be difficult to uniformly and homogeneously The polymer material is selectively patterned.

The wet chemical and dry etch processes include material intensive, time consuming, and expensive processing steps:

A. Masking areas that are not to be etched, for example by

Photolithography: producing a negative or positive image of the etched structure (depending on the photoresist), drying the photoresist, exposing, developing, rinsing, and if necessary drying the surface of the coated substrate

B. Etching the structures by the following methods:

- impregnation method (for example wet etching in a wet chemical bed): immersing the substrates in an etching bath, etching the procedure, repeating the rinsing in a stepped water bath, drying

Spin coating or spraying: applying the etching solution to a rotating substrate. The etching operation may be carried out without/with energy input (for example IR or UV radiation), followed by rinsing and drying

Dry etching, such as, for example, plasma etching in an expensive vacuum unit or etching with a reactive gas in a flow reactor.

As mentioned above, the disadvantages of these etching methods that have been described are due to time consuming, material intensive, expensive processing steps which in some cases have complexity or batching from a process or safety point of view. get on.

It is therefore an object of the present invention to provide a time-saving, inexpensive process for etching polymer surfaces which can be an industrial scale process having high polymer surface efficiencies and throughputs, and which is more conventional than liquid or gas phase. Wet It is much cheaper than dry etching. Moreover, the purpose of the present invention is to provide an inexpensive method for homogenous and uniform structuring and/or patterning of a flexible polymer matrix comprising a second material. In particular, the purpose of the present invention is to provide a suitable method for the selective structuring of polymer matrices comprising silver nanotubes (also known as silver nanowires or silver wires). In particular, the object of the present invention is to provide a method of etching a polymer matrix containing such a silver nanotube, wherein the polymer matrix comprises or consists of polyethylene terephthalate (PET), polyamine Acid ester or poly(ethylene naphthalate) [PEN]. In particular, the object of the present invention is to provide a method of selectively etching a polymer matrix having a silver nanotube on PET.

A number of experiments have been found to provide a new method for selectively etching a polymer matrix containing a silver nanotube (also known as a silver nanowire or a silver wire; hereinafter simply referred to as a silver nanotube), which comprises the following steps a Applying an alkaline etching paste to the plastic substrate, b) heating, and c) cleaning the substrate.

Suitable etching compositions comprise an alkaline etchant selected from the group consisting of KOH, Ca(OH) ₂ , NaOH, TMAH, ethylenediamine, TMEH, SiOH, diethanolamine or triethanolamine.

The etching paste applied in the method comprises a solvent selected from the group consisting of 1,4-butanediol, butyrolactone, ethanol or methanol, preferably 1,4-butanediol. Particularly suitable etching pastes comprise organic and/or inorganic fillers. Thus the applied etch paste can comprise a particulate filler. These fillers may be organic and/or inorganic. These fillers are preferably organic polymer particles.

The etching paste used in accordance with the present invention can be applied to the substrate in a number of different ways. The paste is preferably printed by screen printing. In a particular embodiment of the invention the etching compositions are applied by rotary screen printing, or stencil printing. Another preferred printing method is embossing. Pastes with suitable properties can also be inkjet or dispensed. In some cases it is preferred to eject or micro-spray the paste with ink. However, another option is to apply the etching paste by spraying or by slanting plate coating.

After or during application of the etching composition to the surface, the substrate is heated in step b) to a temperature between about 40 and 140 ° C, preferably between about 60 and 120 ° C. At least a few seconds to a few minutes. In a preferred embodiment, the substrate is heated to a temperature of from about 70 to 90 ° C for at least 1 to 3 minutes. More preferably, the heating step lasts for about 2 minutes, whereby the temperature is about 80 °C.

After the etching, the treated substrate is cleaned using a solvent in step c) and the substrate is dried. This means that the substrate is rinsed with a solvent and dried with air or a stream of nitrogen. The substrate is preferably rinsed with deionized water and dried using dry air or a stream of nitrogen.

One embodiment of the invention is that the method disclosed herein is applicable to the etching of flexible and flexible plastic substrates composed of a polymer. These substrates preferably comprise a polymer selected from the group consisting of polyurethanes, PEN or PET. Experiments have shown that the method is suitable for etching extremely narrow lines or structures having a high resolution of at least 100 μm.

The present invention provides a method of forming features in or on a particularly uneven flexible substrate comprising a polymer matrix. Substrates suitable for processing in accordance with the present invention are not particularly limited by size or planar geometry. The method of the present invention is not limited by surface roughness and can be applied to heterogeneous surface morphology (i.e., substrates having variability in smoothness and roughness).

The surface features produced by the method of the present invention can generally be classified as conformal features, or subtractive features, based on the surface height relative to the plane of the substrate. The surface features produced by the method of the present invention may additionally be classified as penetrating surface features depending on whether the base of the surface features penetrates beneath the substrate plane on which the surface features are formed. As used herein, "penetration distance" means the distance between the lowest point of the substrate and the height of the substrate adjacent the surface feature. More often, the penetration distance of the surface features represents the lowest point relative to the plane of the substrate. Thus, the feature "penetrates" when the lowest point of the feature is below the plane of the substrate on which the feature lies. The non-penetrating surface feature can be said to have a zero penetration distance.

Surface features can be further differentiated according to their composition and function. For example, surface features produced by the method of the present invention include structural surface features and conductive surface features. Finished products including these surface features may also include semiconducting surface features, insulating surface features, and masking surface features. As used herein, "structural surface" means a surface feature having a composition that is similar or identical to the composition of the substrate on which the surface features are located.

"Electrically conductive features" in accordance with the present invention mean surface features having a conductive or semi-conductive composition. The "conductive feature" is preferably a conductive composition Based on. The "conductive features" are preferably based on a composition whose electrical conductivity is based on a composition comprising a metal compound.

Further, "insulating features" means surface features having an electrically insulating composition. By "shading feature" is meant a surface feature that has a composition that does not react with an agent that is reactive with the substrate region adjacent to and surrounding the surface feature. Thus, the masking feature can be used to protect a substrate region during subsequent processing steps such as, but not limited to, etching, deposition, implantation, and surface treatment steps. In some embodiments, the masking feature is removed during or after subsequent processing steps. In accordance with the present invention, a method of selectively etching a surface comprising a polymer and a conductive material is provided, which does not require any masking features.

Feature size and measurement

The surface features produced by the method of the present invention have lateral and vertical dimensions, often defined in units of length, such as angstroms (Å), nanometers (nm), millimeters (mm), centimeters (cm), and the like.

When the surface area of the feature encircling the surface is planar, the lateral dimension of the surface feature can be determined by the vector size between two points on opposite sides of the surface feature, wherein the two points are in the plane of the substrate and wherein The vector is parallel to the plane of the substrate. In some embodiments, two points for determining the lateral dimension of the symmetrical surface feature are also located on the mirror surface of the symmetrical feature. In some embodiments, the lateral dimension of the asymmetrical surface feature can be determined by orthogonally aligning a vector to at least one edge of the surface feature.

When the radius of curvature of the surface of the substrate exceeds 100 μm or more The surface of the substrate is "curved" when the distance on the face, or the distance over the surface of the substrate that is 1 mm or larger, is non-zero. With respect to a curved substrate, the lateral dimension is defined as the size of the circumferential arc segment joining the two points on the opposite side of the surface feature, wherein the circle has a radius corresponding to the radius of curvature of the substrate. The lateral dimension of a curved surface or undulating substrate having a plurality of or varying curvatures can be determined by summing the arc segments of a plurality of circles.

In some embodiments, the surface features produced by the method of the invention have at least one transverse dimension of from about 40 nm to about 100 μm. In some embodiments, at least one lateral dimension of the surface features produced by the method of the invention has about 40 nm, about 50 nm, about 60 nm, about 70 nm, about 80 nm, about 100 nm, about 150 nm, about 200. Nm, about 250 nm, about 300 nm, about 400 nm, about 500 nm, about 600 nm, about 700 nm, about 800 nm, about 900 nm, about 1 μm, about 2 μm, about 3 μm, about 4 μm, A minimum size of about 5 μm, about 10 μm, about 15 μm, or about 20 μm. According to printing techniques, in some embodiments at least one lateral dimension of the surface features produced by the method of the invention has about 100 μm, about 90 μm, about 80 μm, about 70 μm, about 60 μm, about 50 μm, about 40 μm. The largest dimension of about 36 μm, about 30 μm, about 25 μm, about 20 μm, about 15 μm, about 10 μm, about 5 μm, about 2 μm, or about 1 μm. The feature size may be greater than 100 μm in some embodiments, as the resolution achieved depends on the printing technique, but preferred feature sizes of the invention are less than 100 μm and the optimal feature size is less than 40 μm.

Surface features produced by the method of the invention in some embodiments It has a penetration distance of about 3 Å to about 100 μm. In some embodiments, the surface features produced by the method of the invention have about 3 Å, about 5 Å, about 8 Å, about 1 nm, about 2 nm, about 5 nm, about 10 nm, about 15 nm below the surface plane. a minimum penetration distance of about 20 nm, about 30 nm, about 50 nm, about 100 nm, about 500 nm, about 1 μm, about 2 μm, about 5 μm, about 10 μm, or about 20 μm. In some embodiments, the surface features produced by the method of the invention have about 1000 μm, about 90 μm, about 80 μm, about 70 μm, about 60 μm, about 50 μm, about 40 μm, about 30 μm below the surface plane. The maximum penetration distance of about 20 μm, about 10 μm or about 5 μm.

In some embodiments, the surface features produced by the method of the invention have from about 1 000:1 to about 1:100 000, from about 100:1 to about 1:100, from about 80:1 to about 1:80, about 50: 1 to about 1:50, about 20:1 to about 1:20, about 15:1 to about 1:15, about 10:1 to about 1:10, about 8:1 to about 1:8, about 5: An aspect ratio of from 1 to about 1:5, from about 2:1 to about 1:2 or about 1:1 (i.e., the ratio of penetration distance to lateral dimension).

The lateral and/or vertical dimensions of the reduced surface features can be determined using analytical methods that measure the surface topography, such as, for example, scanning atomic force microscopy (AFM) or surface leveling. Conformal surface features are generally not measurable by surface leveling methods. However, if the end of the surface of the conformal feature is a functional group having a polarity different from that of the surrounding surface region, the lateral dimension of the surface feature can be utilized, for example, intermittent contact AFM, functionalized AFM or scanning probe microscopy. Got it.

Surface features can also be utilized based on properties such as, but not limited to, conductivity, resistivity, density, magnetic permeability, porosity, hardness, and combinations thereof, for example, scanning probe microscopy.

In some embodiments, surface features can be utilized, for example, by scanning electron microscopy or transmission electron microscopy to distinguish from surrounding surface areas.

In some embodiments, the surface features have a different composition or morphology than the surrounding surface area. Thus, surface analysis methods can be used to simultaneously determine the composition of the surface features and the lateral dimensions of the surface features. Analytical methods suitable for determining the composition and lateral and vertical dimensions of surface features include, but are not limited to, Auger electron spectroscopy, energy dispersive x-ray spectroscopy, micro Fourier transform infrared spectroscopy, particle induction x- Radiation, Raman spectroscopy, x-ray diffraction, x-ray fluorescence, laser ablation induced coupled plasma mass spectrometry, rasape backscatter spectroscopy/hydrogen forward scattering, secondary ion mass spectrometry, Time-of-flight secondary ion mass spectrometry, x-ray photoelectron spectroscopy, and combinations thereof.

Paste composition

The phrase "paste" according to the present invention means a heterogeneous composition having a viscosity of from about 1 denomination (cP) to about 10 ⁶ cP. "Heterogeneous composition" means a composition having more than one excipient or component. As used herein, "paste" can mean a viscous liquid or a semi-solid. The paste used in conjunction with the present invention in some embodiments has an adjustable viscosity and/or a viscosity that can be controlled by one or more extrinsic conditions. In a preferred embodiment the paste represents a composition having thixotropic properties, which means that the viscosity changes with effective pressure, and more precisely these pastes have beneficial non-Newtonian flow behavior.

In some embodiments, the paste used in conjunction with the present invention has a viscosity of from about 1 cP to about 10 ⁶ cP. In some embodiments, the paste used in conjunction with the present invention has about 1 cP, about 2 cP, about 5 cP, about 10 cP, about 15 cP, about 20 cP, about 25 cP, about 30 cP, about 40 cP, About 50 cP, about 60 cP, about 75 cP, about 100 cP, about 125 cP, about 150 cP, about 175 cP, about 200 cP, about 250 cP, about 300 cP, about 400 cP, about 500 cP, about 750 The minimum viscosity of cP, about 1000 cP, about 1250 cP, about 1500 cP, or about 2000 cP. In some embodiments, the paste used in conjunction with the present invention has about 15 000 cP, about 10 000 cP, about 9 500 cP, about 9 000 cP, about 8 500 cP, about 7 500 cP, about 7 000 cP, about 6 500 cP, approximately 6 000 cP, approximately 5 500 cP, approximately 5 000 cP, approximately 4 000 cP, approximately 3 000 cP, approximately 2 000 cP, approximately 1 000 cP, approximately 500 cP, approximately 250 cP, approximately 100 cP Or a maximum viscosity of about 50 cP. The applied paste preferably exhibits a viscosity of between about 1000 cP and 15 000 cP, but in general the paste is selected to exhibit the optimum viscosity for a particular application.

In some embodiments, the viscosity of the paste used can be controlled. Parameters that can control the viscosity of the paste include, but are not limited to, the average length, molecular weight, and/or degree of crosslinking of the polymer or copolymer; and the presence of the solvent and the concentration of the solvent; the thickener (ie, the viscosity adjusting component) The presence of the thickener (which may be particulate), the concentration of the thickener, the particle size of the particulate component present in the paste, and the free volume of the compound present in the paste. (ie, porosity); swelling of the compound present in the paste; ionic interaction between oppositely charged and/or locally charged species present in the paste (ie, solvent thickener interaction); And their combinations. It is especially preferred to add a thickening agent to the three-dimensional network structure which will change if pressure is applied to the paste composition and will re-establish if the pressure is again lowered.

In a preferred embodiment, the paste suitable for use in conjunction with the present invention comprises a solvent and a thickening agent. In some embodiments, a combination of solvent and thickener can be selected to adjust the viscosity of the paste. Without being bound by any particular theory, the viscosity of the paste is an important parameter in the fabrication of surface features having a lateral dimension of from about 40 nm to about 100 μm.

The viscosity of a printable homogeneous etching paste having a non-Newtonian flow behavior as described in accordance with the present invention is achieved by a thickening agent which forms a network structure or swells in the liquid phase and which varies depending on the desired application area. A printable etch paste having a non-Newtonian flow behavior as described in accordance with the present invention includes an etch paste having a viscosity that has to be dependent on the shear rate, particularly an etch paste having a shear thinning effect. The network structure made from the thickener collapses under shear stress. Repair of the network structure can be carried out without time delay (non-Newtonian etching paste with plastic or pseudoplastic flow behavior) or with time delay (etching paste with thixotropic flow behavior).

Printable homogeneous pastes with non-Newtonian flow behavior are fully homogenized by the addition of a thickener. A particulate thickener such as, for example, a particulate polyoxyalkylene or an acrylic resin can be used.

Thickeners suitable for use in conjunction with the pastes of the present invention include, but are not limited to, a metal salt of a carboxyalkyl cellulose derivative (for example, sodium carboxymethyl cellulose), an alkyl cellulose derivative (for example, methyl cellulose and ethyl cellulose), a partially oxidized alkane Cellulose derivatives (for example, hydroxyethyl cellulose, hydroxypropyl cellulose and hydroxypropyl methylcellulose), starches, polypropylene guanamine gels, poly-N-vinylpyrrolidone Homopolymers, poly(alkyl ethers) (eg, polyethylene oxide and polypropylene oxide), agar, agar, xanthan gum, animal glue, dendrimers, colloidal cerium oxide, and combinations thereof. Other suitable thickeners include the following thickeners

̇-functionalized methacrylate units, especially cationic methacrylate/methacrylamide, such as Borchigel® A PK

̇ functionalized vinyl unit, ie

- Polyhydric alcohols with varying degrees of hydrolysis, especially Mowiol® 47-88 (partially hydrolyzed, ie vinyl acetate and vinyl alcohol units) or Mowiol® 56-98 (fully hydrolyzed) or -polyvinylpyrrolidone Class (PVP), especially PVP K-90 or PVP K-120

These thickeners can be used individually or in combination with other thickeners mentioned above.

According to the present invention, the thickening agent is from about 0.1% to about 15%, from about 0.5% to about 15%, preferably from about 5 to about 15%, from about 6.5% to about 13%, by weight of the paste. A concentration of from 7 to 13%, or from about 8% to about 12%, is present in the etch paste.

The thickener is preferably present in an amount of from about 8 to 15% of the total composition, more preferably Add 10 to 13% of the ground.

In some embodiments, the particle size or body length of the components in the paste may have to be reduced because the lateral dimension of the desired surface features is reduced. For example, to have surface features having a lateral dimension of about 100 nm or less, it may be necessary to reduce or remove the polymer component of the paste composition.

Generally, the paste contains a solvent. Paste according to the present invention suitable solvents include, but are not limited to, water, C ₁ -C ₈ alcohols (e.g., methanol, ethanol, propanol and butanol), C ₆ -C ₁₂ straight chain, branched and cyclic hydrocarbons (for example, hexane and cyclohexane), C ₆ -C ₁₄ aryl and aralkyl hydrocarbons (for example, benzene and toluene), C ₃ -C ₁₀ alkyl ketones (for example, acetone), C ₃ - C ₁₀ esters (eg, ethyl acetate), C ₄ -C ₁₀ alkyl ethers, and combinations thereof. It is preferred to add a solvent (preferably 1,4-butanediol) selected from 1,4-butanediol, butyrolactone, ethanol or methanol or a mixture thereof to produce the paste. In addition to these solvents or a single solvent, the pastes may contain a certain amount of water. If KOH or NaOH is a effective etchant, the paste typically contains water. The KOH, NaOH or Ca(OH) ₂ is typically dissolved in pure water, especially deionized water, prior to preparation of the paste. In some embodiments, the solvent is present in the paste at a concentration of from about 20% to about 65% by weight. In some embodiments, the solvent is about 65%, about 64%, about 63%, about 61%, about 55%, about 50%, about 40%, about 30%, about 25 by weight of the paste. % or about 20% of the maximum concentration is present. In some embodiments, the solvent is a minimum concentration of about 20%, about 22%, about 25%, about 30%, about 40%, about 50%, about 60%, or about 65% by weight of the paste. presence. Therefore, the etching composition may comprise KOH, Ca(OH) ₂ , NaOH, TMAH, ethylenediamine, TMEH, SiOH, diethanolamine and triethanolamine as etchants, and the etchants are soluble in water or a mixture of water and other solvents. in.

In some embodiments of the invention, the paste used additionally comprises an additive having properties beneficial to the intended purpose. Additives of this type are defoamers (such as, for example, those available under the trade name TEGO® Foamex N), thixotropic agents (such as BYK® 410, Borchigel® Thixo2), flow control agents (eg, TEGO® Glide). ZG 400), degassing agents (eg TEGO® Airex 985) and adhesion promoters (eg Bayowet® FT 929). These additives may have a positive effect on the printability of the printing paste and also have a positive effect on the etch depth and results.

In some embodiments, the paste additionally comprises a surfactant. The surfactant present in the paste changes the surface energy of the stamp and/or substrate to which the paste is applied, thereby improving the wetting of the surface by the paste. Surfactants suitable for use in conjunction with the present invention include, but are not limited to, fluorocarbon surfactants including aliphatic fluorocarbon groups (e.g., ZONYL® FSA and FSN fluorosurfactants, EI Du Pont de Nemours and Co., Wilmington, DE), fluorinated alkyl alkoxylates (eg, FUORAD® surfactants, Minnesota Mining and Manufacturing Co., St. Paul, MN), hydrocarbon surfactants having aliphatic groups (eg, An alkylphenol ethoxylate comprising an alkyl group having from about 6 to about 12 carbon atoms, such as a octylphenol ethoxylate available under the tradename TRITON® X-100, Union Carbide, Danbury, CT), Polyoxyalkylene surfactants such as decanes and decanes (for example, polyoxyethylene modified polydimethyl siloxane such as DOW CORNING® Q2-5211 and Q2-5212, Dow Corning Corp., Midland, MI), fluorinated oxane surfactants (eg, fluorinated polydecanes such as LEVELENE® 100, Ecology Chemical Co., Watertown MA); and combinations thereof.

In accordance with a particular embodiment of the invention, a suitable paste additionally must contain an etchant. As used herein, "etchant" means a component that is capable of reacting with a substrate to remove a portion of the substrate. The etchant is therefore used to form a subtractive feature and react with the substrate to form at least one of a volatile material, or a residue, particulate or debris that can diffuse from the substrate, the at least one being capable of For example, a rinse or cleaning procedure is removed from the substrate. Generally, in accordance with the present invention, suitable etchants are KOH, NaOH or Ca(OH) ₂ as previously mentioned, but preferably KOH is used as an etchant and is from about 15% to about 5% by weight of the paste. A concentration of 35%, from about 17% to about 30%, or from about 20% to about 30%, is present in the paste according to the invention. These etchants can be combined with other alkaline etchants mentioned below.

The composition and/or morphology of the substrate that reacts with the etchant is preferably a polymer surface comprising a conductive material. The subtractive feature formed by the reaction of the etchant with the substrate is also not particularly limited as long as the material reactive with the etchant can be removed from the resulting reduced surface features. Without being bound by any particular theory, an etchant may be formed by removing material from such a surface by reaction with the substrate, for example, volatile products, residues removed from the substrate by a rinsing or cleaning procedure, Particles or debris. For example, an etchant can react with a polymer that builds the surface by forming a soluble or volatile species. In some embodiments, the etchant can react with the substrate to form a water soluble ionic species. Suitable for removing residues formed by the reaction of an etchant with a surface Or a method of microparticles is disclosed, for example, in U.S. Patent No. 5,894,853, the disclosure of which is incorporated herein in its entirety by reference.

An etchant suitable for use with the present invention includes an alkaline etchant as described above. The alkaline etchant suitable for use in conjunction with the present invention preferably comprises potassium hydroxide, which may be etchant like sodium hydroxide, calcium hydroxide, ammonium hydroxide, tetraalkylammonium hydroxide, ammonia, ethanolamine, ethylene. The amines and combinations thereof are combined, but the best etchant is potassium hydroxide itself. It has been found that the surface of the flexible polymer comprises or consists of a polymer matrix and a silver nanotube (this term is used herein and the term "silver nanotube" also means between 1 and 100 nm. a "silver wire" and "silver nanowire" having a diameter and a dimension of one hundred nanometers, wherein the polymer matrix comprises or consists of polyethylene terephthalate (PET) , a polyurethane or poly(ethylene naphthalate) [PEN], and if applied comprises from about 15 to 35% by weight of the total composition, preferably between 20 The etching paste to a concentration of 30% KOH can be selectively etched with high resolution.

In a preferred embodiment, the flexible polymer surface comprises a conductive component. As used herein, "conductive component" means a compound or species that is capable of transferring or moving a charge. Conductive components suitable for use with the present invention include, but are not limited to, metals, nanoparticles, polymers, and combinations thereof. In some embodiments, the electrically conductive component is present in the polymer surface at a concentration of from about 1% to about 90% by weight.

Metals suitable for use with the present invention include, but are not limited to, transition metals, aluminum, bismuth, phosphorus, gallium, germanium, indium, tin, antimony, lead, antimony, alloys thereof. And their combinations. In a preferred embodiment of the invention, the polymer surface comprises silver in the form of nanoparticles (i.e., particles having a diameter of 100 nm or less, or from about 0.5 nm to about 100 nm). Nanoparticles suitable for use with the present invention can be homogeneous, multilayered, functionalized, and combinations thereof. It is preferably formed into a nanotube-like tubular shape.

The method of the present invention is particularly useful for etching flexible and flexible plastic substrates composed of a polymer, especially a polymer selected from the group consisting of polyurethane, PET or PEN. Experiments have accordingly shown that the method is suitable for etching very narrow lines or structures having a high resolution of at least 100 μm.

The paste used in the present invention may contain a conductive component and a reactive component. For example, the reactive component present in the paste can promote at least the reaction between the etchant and the substrate, the adhesion between the paste and the substrate being etched, and combinations thereof. The surface features formed by the reaction of the paste composition include subtractive penetration, conformal penetration reduction penetration, and conformal penetration surface features.

The present invention includes the use of an etchant-containing paste that can be applied to fabricate a reduced surface feature having conductive feature inserts therein.

Substrate

Substrates suitable for patterning by the method of the present invention include materials that are capable of contacting the surface of the stamp or screen. Substrates suitable for patterning by the method of the present invention include films, films, laminates, foils, plastics, polymers, and combinations thereof. In some embodiments, the substrate is selected from the group consisting of variations in porosity of any of the above materials.

Substrates that can be patterned by the method of the present invention comprise flexible substrates such as plastics, composites, laminates, films, metal foils, and combinations thereof. In some embodiments, the flexible material can be patterned in a reel-to-reel manner by the method of the present invention. Preferably, the etch paste is transferred to a surface of the substrate that can be etched by printing techniques. In particular, screen printing, screen printing, pad printing, stamp printing, and ink jet printing methods are well known printing methods. Manual application is also possible.

The present invention contemplates the efficiency, efficiency, and efficiency of the processing steps by selecting a paste suitable for a particular substrate (i.e., polyethylene terephthalate (PET), which is typically a low molecular weight polymer that exhibits high burst safety). Cost and speed are optimized.

The etching can be carried out at ambient temperature, such as room temperature. However, the etching reaction can also be activated by energy input, for example by convection and thermal radiation by IR emitters, UV or laser radiation, with the result that the temperature at the reaction site just above the surface is increased to about 300. °C. If applicable, the reaction on the substrate is initiated by at least one type of radiation, for example, by ultraviolet light, which can be used by ultraviolet light-initiated paste, and the ultraviolet light causes the substrate to be front side The reaction of the paste can be initiated by irradiation of the back side of the substrate with ultraviolet light. The reaction is preferably initiated by IR waves and increases the surface temperature. The etching is preferably carried out at a temperature of up to 180 ° C, preferably under mild conditions at a temperature of up to 100 ° C. This means that the etching itself can be carried out in a wide range of temperatures between about 20 and 300 ° C, but depending on the chemistry of the surface being etched, the etching temperature is adjusted from room temperature to 180 ° C. In the scope. However, if a good etching result can be achieved, the temperature can also be adjusted to a temperature of up to 100 ° C. Typically, the etching of the polymer surface is carried out at a lower temperature and the etching of the inorganic surface can be carried out at a higher temperature of up to 300 °C.

Impression, template or screen

As used herein, "stencil" means a three-dimensional object having a score defining a pattern on at least one surface of the stamp. The stamps used in conjunction with the present invention are not particularly limited by geometry and may be flat, curved, smooth, rough, wavy, and combinations thereof. In some embodiments, the stamp can have a three-dimensional shape suitable for conformal contact with the substrate. In some embodiments, the stamp can comprise a plurality of patterned surfaces, the surfaces comprising the same or different patterns. In some embodiments, the stamp comprises a cylinder, wherein one or more scores in the curved face of the cylinder are indicative of the contour of the graphic. Since the cylindrical stamp rolls over the surface, the pattern repeats. The paste or ink can be applied to the cylindrical stamp as it rolls. For stamps having multiple patterned surfaces: the cleaning, application, contacting, removing, and reacting steps can occur simultaneously to apply different surfaces of the same stamp.

The stamps used in accordance with the present invention are not particularly limited by materials and may be comprised of a variety of materials such as, but not limited to, glass (e.g., quartz, sapphire, borosilicate glass), ceramics (e.g., metal carbides, metal nitrogen). Manufactured, metal oxides, plastics, metals, and combinations thereof. In some embodiments, the stamp used in conjunction with the present invention comprises an elastomeric polymer.

As used herein, "elastomer stamp" means a molded three-dimensional object A body comprising an elastomeric polymer and having at least one surface of the stamp having a contoured outline of the pattern. More commonly, a stamp comprising an elastomeric polymer is referred to as an elastomeric stamp. As used herein, "elastomer template" means a molded three-dimensional object comprising an elastomeric polymer and having at least one opening penetrating the opposite surfaces of the template to form an opening in the die face of the three-dimensional object. The elastomeric stamp or stencil may additionally comprise a rigid flexible, porous or woven substrate material, or any other that prevents deformation of the stamp or stencil when the stamp or stencil is used during processing as described herein. mechanism. Similar to the stamp, the elastomeric template used in conjunction with the present invention is not particularly limited by geometry and can be flat, curved, smooth, rough, wavy, and combinations thereof.

Elastomeric polymers suitable for use in conjunction with the present invention include, but are not limited to, polydimethylsiloxane, polysesquioxanes, polyisoprene, polybutadiene, polychloroprene, iron Fluorine and its combination. Other suitable materials and methods for making elastomeric impressions suitable for use in conjunction with the present invention are disclosed in U.S. Patent Nos. 5,512,131; 5,900,160; 6,180,239; and 6,776,094; 10/766,427, herein incorporated by reference in its entirety.

Pastes may be by methods known in the art such as, but not limited to, screen printing, ink jet printing, syringe deposition, spray coating, spin coating, brush coating, and combinations thereof, as well as other common familiarity with coated surfaces. The known application method is applied to the surface of the stamp or the surface of the substrate. In some embodiments, the paste is poured onto the surface of the stamp and the blade is then moved laterally across the surface to ensure that the score in the stamp completely and evenly fills the paste. The scraper can also self-print the surface Remove excess paste. Applying the paste to the substrate or the surface of the stamp may comprise rotating the surface at about 100 revolutions per minute (rpm) to about 5,000 rpm, or from about 1,000 rpm to about 3,000 rpm, while pouring or spraying the paste on the surface. Rotate on the surface.

Preferably, the paste is applied to the stamp to completely and evenly fill at least one of the scores in the surface of the stamp. Without being bound by any particular theory, since the lateral dimension of the score in the stamp is less altered, the viscosity of the paste should be reduced to ensure that the pattern in the stamp is evenly filled during the application step. Improper application of the paste to the stamp can result in the inability to correctly and reproducibly produce surface features having the desired lateral dimensions. Other suitable embodiments for printing are screen printing, web printing, swashplates, and dispensing printing or spraying. If the viscosity of the composition is moderately adjusted, jet printing can also be performed. In some embodiments disclosed above, the composition of the paste can be formulated to control its viscosity such that it can be applied by screen printing. Parameters that can control paste viscosity include, but are not limited to, solvent composition, solvent concentration, thickener composition, thickener concentration, particle size of the component, molecular weight of the polymer component, cross-linking degree of the polymer component, Free volume (i.e., porosity) of the components, swelling of the components, ionic interaction between the paste components (e.g., solvent-thickener interaction), and combinations thereof.

In some embodiments, the viscosity of the paste changes during one or more of the application step, the contacting step, the reaction step, or a combination thereof. For example, when the paste is applied to the surface of the stamp to ensure that the score in the surface of the stamp is completely and evenly filled, the viscosity of the paste is lowered. After the coated stamp is in contact with the substrate, the viscosity of the paste is increased to ensure a horizontal ruler of the score in the stamp. The inch is transferred to the lateral dimension of the surface features formed on the substrate.

Without being bound by a particular theory, the viscosity of the paste can be controlled by external stimuli such as temperature, pressure, pH, with or without reactive species, current, magnetic field, and combinations thereof. For example, increasing the temperature of the paste often reduces its viscosity; and increasing the pressure applied to the paste often increases its viscosity, with the exception of thixotropy.

The pH of the paste increases or decreases the viscosity of the paste as a function of the total solubility of the component mixture as a function of pH, as a function of one or more components of the paste. For example, a weakly acidic aqueous paste containing the polymer having a reduced viscosity often less than the pK _a of the polymer, since the solubility of the polymer will increase under its pK _a. However, if the protonation of the polymer results in an ionic interaction between the mold polymer and another component of the paste which reduces the solubility of the polymer, the viscosity of the paste may increase. Careful selection of the paste component allows the paste viscosity to be controlled over a wide range of pH values.

Transferring the paste from the surface of the stamp or another printing device to the substrate can be achieved between the paste and the surface of the printing device by adhesion between the paste and a region of the substrate. One or more interactions between the paste and the substrate, between the surface of the stamp or printing device and the substrate, and combinations thereof. Without being bound by a particular theory, the adhesion of the paste to the substrate can be achieved by gravity, van der Waals interaction, covalent bonds, ionic interactions, hydrogen bonding, hydrophilic interactions, hydrophobic interactions, magnetic interactions and Combination promotion. Accordingly, the etch paste is preferably formed such that these interactions between the paste and the surface of the stamp or the printing device are minimized and the paste is transferred from the surface of the stamp or the printing device to the substrate. .

In some embodiments, contacting the stamp or elastomeric template or printing screen with the surface of the material can be facilitated by applying the pressure or vacuum to the back side of one or both of the stamp, the template, and the surface. In some embodiments, the application of this pressure or vacuum ensures substantial removal of the paste from the surface of the stamp or template and material. In some embodiments, the application of the pressure or vacuum ensures conformal contact between the surfaces. In some embodiments, the application of the pressure or vacuum may cause bubbles present between the stamp and the surface of the substrate, or bubbles present in the score of the surface of the stamp, or in the paste reaction The rate of occurrence of bubbles previously present in the paste is minimized. Without wishing to be bound by any particular theory, the removal of the bubbles can contribute to the reproducible formation of surface features having a lateral dimension of 100 μm or less.

In some embodiments, the surface of the substrate and/or the surface of the printing device, such as a stamp, can be selectively patterned, functionalized, derivatized, textured, or otherwise pretreated. As used herein, "pretreatment" means chemically or physically modifying the surface prior to application or reaction of the paste. Pretreatment can include, but is not limited to, cleaning, oxidizing, reducing, derivatizing, functionalizing, exposing to reactive gases, exposure to plasma, exposure to thermal energy (eg, convective thermal energy, radiant thermal energy, conductive heat, and combinations thereof), Exposure to electromagnetic radiation (eg, x-rays, ultraviolet light, visible light, infrared light, and combinations thereof), and combinations thereof. Without wishing to be bound by any particular theory, pre-processing the surface of the stamp and/or substrate will increase or decrease the adhesive interaction between the paste and the surface and contribute to the formation of surface features having a transverse dimension of 100 μm or less.

For example, derivatizing the surface of the stamp and/or substrate with a polar functional group (eg, oxidizing the surface) can promote surface wetting by a hydrophilic paste and by thinning The aqueous paste prevents surface wetting. Furthermore, hydrophobic and/or hydrophilic interactions can be used to prevent paste from penetrating the stamp body. For example, derivatization of the surface of the stamp with a fluorocarbon functional group promotes transfer of the paste from the stamp to the surface of the material.

The method of the present invention produces surface features by reacting a paste with a region of the substrate. As used herein, "reaction" means initiating a chemical reaction comprising at least one of the following: reacting one or more components present in the paste with one another to cause one or more components of the paste to react with the surface of the substrate to render a paste One or more components react with the subsurface regions of the substrate, and combinations thereof.

According to the invention, the reaction comprises applying a paste to a substrate. This means, for example, that the reaction is initiated by contact between the paste and the surface of the substrate.

Thus, the reaction of the paste comprises a chemical reaction between the paste and a functional group on the substrate, or a chemical reaction between the paste and a functional group below the surface of the substrate. Accordingly, the method of the present invention comprises reacting a component of the paste or paste not only with the surface of the substrate but also with a region of the substrate below the surface to form an insertion feature or a mosaic feature on the substrate. Without wishing to be bound by any particular theory, the components of the paste can react with the substrate by reacting on the surface of the substrate, or infiltrating and/or diffusing into the substrate. In some embodiments, the penetration of the paste into the surface of the substrate can be facilitated by applying physical pressure or vacuum to the back side of the stamp, template, substrate, or combination thereof.

The reaction between the paste and the substrate changes one or more properties of the substrate, wherein the property change is in the portion of the substrate that reacts with the paste.

Preferably, reacting the paste with the substrate comprises reacting to the plane of the substrate (i.e., the bulk) and the reaction in the sides of the surface of the substrate. For example, the reaction between the etchant and the substrate involves infiltrating the etchant The surface of the substrate (i.e., infiltrated orthogonally to the surface) such that the lateral dimension of the lowest point of the surface feature is approximately equal to the size of the feature at the surface of the substrate.

In some embodiments, the etching reaction also occurs laterally between the paste and the substrate such that the lateral dimension at the bottom of the surface features is narrower than the lateral dimension of the features at the plane of the surface. As used herein, "bottom erosion" refers to the situation when the lateral dimension of the surface features is greater than the lateral dimension of the stamp used to apply the paste forming the surface features. Typically, the undercut is caused by the reaction of an etchant or reactive species with the surface in the lateral dimension and results in the formation of a beveled edge on the subtractive feature.

The paste compositions used in conjunction with the present invention are formulated to minimize the reaction of the paste in the lateral dimensions of the surface (i.e., to minimize undercut). Without wishing to be bound by any particular theory, the undercut is preferably minimized by the use of a photoactivated paste (i.e., a paste that reacts with the surface upon exposure to radiation). Irradiating the paste initiates a reaction between the paste and the surface through the back side of the transparent surface. Because the light only illuminates the surface of the paste that reacts perpendicularly to the surface, the paste along the sidewalls of the reduced surface features is not exposed to ultraviolet light, thereby minimizing lateral etching of the surface. This technique is generally suitable for any reaction initiator for this surface. In some embodiments, the reaction initiator can activate the paste through the back side of the stamp or elastomeric template.

The undercut can also be minimized by using a substrate having an anisotropic composition or structure such that it is etched in a vertical direction compared to the lateral dimension etch preference. Some materials are inherently anisotropic, and anisotropy can also be introduced by, for example, pretreating a substrate with chemicals or radiation and combinations thereof.

The paste reaction can comprise removing the solvent from the paste. Without wishing to be bound by any particular theory, the removal of the solvent from the paste will cure the paste or catalyze the crosslinking reaction between the components of the paste. With regard to a paste containing a solvent having a low boiling point (for example, a boiling point < 60 ° C), the solvent can be removed without heating the surface. Solvent removal can also be achieved by heating the surface, paste, or a combination thereof.

In some embodiments, the reaction comprises exposing the paste to a reaction initiator. Reaction initiators suitable for use in connection with the present invention include, but are not limited to, thermal energy, electromagnetic radiation, sound waves, acids or bases (eg, lowering or raising pH), raising or lowering pressure, alternating or direct current, agitation, sonication Processing and combinations thereof. In some embodiments, the reaction comprises exposing the paste to a plurality of reaction initiators.

Electromagnetic radiation suitable as a reaction initiator can include, but is not limited to, microwave light, infrared light, visible light, ultraviolet light, x-rays, radio frequency, and combinations thereof.

In some embodiments, the stamp or elastomeric template is removed from the substrate prior to the paste reaction. In some embodiments, the stamp or elastomeric template is removed from the substrate after the paste reaction.

In some embodiments, the substrate is patterned using microcontact printing prior to applying the etch paste to the substrate. For example, the ink can be applied to an elastomeric stamp having at least one score in the surface of the elastomeric template of the pattern profile to form a coated elastomeric stamp and the coated impression The mold is in contact with the substrate. The ink is transferred from the surface of the coated elastomeric stamp to the substrate by a pattern defined on the substrate by a pattern in the surface of the elastomeric stamp. The ink adheres to the surface and will At least one of a film, a single layer, a double layer, a self-assembled single layer, and a combination thereof is formed. In some embodiments, the ink will react with the substrate. The paste is then applied to the substrate, wherein the paste is exposed to the substrate or by the ink pattern, screen printing, inkjet printing, ejector deposition, spray coating, spin coating, brush coating, and combinations thereof And one of the substrate regions covered by conventional application methods known to those skilled in the art of coating the surface is reactive. The paste, any residual paste and/or ink and reaction products on the substrate can be removed after the reaction. The resulting patterned substrate comprises a pattern having a transverse dimension determined by a pattern used to apply the ink to the surface of the elastomeric stamp of the substrate, and transferred during the paste deposition process Any pattern to the substrate.

Other preferred printing devices

In a preferred embodiment of the invention, the etching paste is by screen printing, screen printing, pad printing or jet printing methods, which are known in the art. Manual application is also possible.

A printable homogeneous etching paste having a non-Newtonian flow behavior as described in accordance with the present invention can be applied throughout the screen according to the design of the screen, screen, clischee or stamp or cartridge addressing. Above the region, or in accordance with the etched structure mask, is selectively applied only where etching is desired. All masking and lithography steps that were needed early are not necessary. As described above, the etching operation may be performed with or without energy input (eg, in the form of thermal radiation (using an IR emitter)). After the etching is completed, a suitable solvent, preferably deionized water, is used. A printable etch paste and reaction product having a non-Newtonian flow behavior is washed away from the etched surface.

The etch depth in the treated surface layer of variable thickness can be adjusted by varying the following parameters, and in the case of selective structure etching, there is also the outline definition of the etched structure;

浓度 etching composition concentration and composition

Concentration and composition of the solvent used

Concentration and composition of ̇ thickener system

浓度 Concentration and composition of any additional additives (such as defoamers, thixotropic agents, flow control agents, deaerators and adhesion promoters)

可 Viscosity of a printable homogeneous etching paste having a non-Newtonian flow behavior as described in accordance with the present invention

蚀刻 during etching with or without energy input to print the surface of the polymer printed with the paste and the surface layer of the polymer, respectively, and ̇ Input energy into the system printed with the etch paste.

All interactions between the etch paste used and the etched surface described above are also effective when the pastes are applied by means other than the use of flexible stencils or stamps.

Method of the invention

As stated above, it is therefore an object of the present invention to provide an etch medium which can have a high potential throughput for a polymer surface for a simple etching process of the technique. This simple etching method is much cheaper than conventional wet and dry etching methods in liquid or gas phase.

This method has been found to be highly selective to polymer matrices when etching such surfaces and when aligning extremely complex circuits fabricated on suitable flexible polymer surfaces.

The most suitable polymer is PET, which is a polyethylene terephthalate polymer, typically a low molecular weight polymer that exhibits high burst safety. Another suitable polymer is PEN, which is a polymer of dimethyl 2,6-naphthalene dicarboxylate and 1,2-ethanediol and which is also known as poly(ethylene naphthalate). This polymer is commercially available under the trade designation "PEN Polymer 18348" or "Developmental PEN 10533 Polyester".

If the surface made from one of these polymers must be etched in accordance with the method of the present invention, the etch paste is printed on the plastic substrate and heated to a temperature of about 80 ° C for at least 90 s and then rinsed with deionized water. The polymer matrix is therefore etched by a paste containing a solvent, potassium hydroxide (KOH), a thickener, and an organic filler content. The method and paste according to the present invention are particularly useful for screen printing and selective etching of minute structures on a plastic substrate, wherein the etching composition can be applied to an elastomeric stamp which exhibits the elasticity of the outline of the pattern At least one score in the surface of the body stamp to form an etch paste coated elastomeric stamp and to bring the coated stamp into contact with the substrate.

The etch paste compositions can be applied to the surface of the substrate to be etched in a single processing step.

Thus, if a special printing technique is used, the method according to the invention can be highly automated and highly processed, which is suitable for transferring the etching paste to the surface of the substrate being etched. In particular, screen printing, screen printing, and shifting Printing, stamp printing, micro-jet printing, and ink jet printing methods are well known and preferred printing methods for those skilled in the art. Manual application is also possible. But the best is the microcontact printing method.

By varying the following parameters, in particular, the etch depth in the polymer-based substrate surface and its variable thickness layer can be adjusted, and in the case of selective structure etching, there is also a clear outline of the etched structure. degree:

浓度 etching composition concentration and composition

Concentration and composition of the solvent used

Concentration and composition of ̇ thickener system

Concentration and composition of ̇ filler content

浓度 Concentration and composition of any additional additives (such as defoamers, thixotropic agents, flow control agents, deaerators and adhesion promoters)

黏 Viscosity of KOH-based etching paste according to the printability of the present invention

蚀刻 During etching with or without energy input to the etch paste and/or the etched substrate.

The etch may last for a few seconds or minutes, depending on the application of the etched structure, the desired etch thickness, and/or the sharpness of the outline. Typically, the etch period is set to a time in the range of from about 30 seconds to about 20 minutes. The etching time is preferably in the range of from about 1 minute to about 15 minutes, more preferably in the range of from about 3 minutes to about 12 minutes.

The etching composition used in accordance with a preferred embodiment of the present invention is a printable KOH-based etching paste composed of an etchant, a solvent, a thickener and a certain amount of filler. Mix to form the paste. The etching composition used may comprise KOH in the range of from about 15 to 35%, preferably from 20 to 30% by weight of the total composition. The etching composition according to the present invention may comprise from about 20 to 65%, preferably from 25 to 55%, by weight of the total composition of the solvent. The thickener may be added in an amount of from about 8 to 15%, preferably from about 10 to 13% by weight of the total composition. The organic and/or inorganic filler may be incorporated in an amount of from about 5 to 20% by weight of the total composition, preferably from about 8 to 15%, and most preferably from about 10 to 13%. In addition to these components, the etching composition may additionally contain additives such as the above-mentioned surfactants and wetting agents and the like. Suitable additives are mentioned above. These additives may be added in an amount of from about 0.01 to 1%, preferably from about 0.1 to 0.5% by weight of the total composition.

This mixing can be carried out in a suitable container equipped with a suitable agitator. This mixing is preferably carried out in a beaker having a magnetic stir bar. This amount of KOH is therefore mixed with the solvent. The thickener was slowly added while stirring the mixture. Thereafter, a suitable amount of filler, preferably particulate filler, is added while stirring the mixture. This mixing can be carried out at room temperature of about 20 to 30 °C. In order to improve the solubility of the components and shorten the time required for mixing, the temperature may be raised to below the boiling point of the solvent to be added, preferably not higher than 70 °C. The mixing is preferably carried out at a temperature in the range of from about 25 to 60 ° C, especially in the range of from 30 to 50 ° C. The prepared etching paste has storage stability at a general storage temperature.

A printable homogeneous etching paste having a non-Newtonian flow behavior according to the present invention as described previously can be used, in particular, all wanting a full area and/or Or a case of structured etching of a polymer surface or a surface comprising such a system, especially a layer made of a polymer such as polyurethane, PEN or PET.

Therefore, the entire surface, as well as individual structures, can be selectively etched into the uniform, solid, non-porous, and porous polymers to a desired depth, i.e., the etching operation can encompass the microstructure of the deep etched structure. All ranges between etchings, especially in the range of such polymeric materials comprising electrically conductive materials such as metal particles or silver nanotubes.

In particular, screen printing, screen printing, pad printing, stamp printing, and ink jet printing methods are suitable techniques for applying the desired paste. In general, in addition to the above printing method, manual application (for example, brush coating) may be used.

A printable homogeneous etch paste having a non-Newtonian flow behavior in accordance with the present invention can be used in all cases of etching the above-described variable thickness polymer layer in a full area and/or in a structured manner.

DETAILED DESCRIPTION OF THE INVENTION The detailed description of the specific embodiments, and the specific embodiments in the specification, the description of the specific embodiments, the However, each specific embodiment may not necessarily include that particular feature, structure, or characteristic. Furthermore, such phrases are not necessarily referring to the specific embodiments. In addition, the specific features, structures, or characteristics of the present invention are described in connection with the specific embodiments.

In summary, the method according to the invention for etching a flexible polymer substrate with a paste as disclosed thus enables a large number of workpieces to be adapted to The method is cheap to etch on an industrial scale.

Even without any other explanation, it can be assumed that the skilled person can use the above description in the broadest sense. The preferred embodiments and examples are therefore to be considered as illustrative only and are in no way limiting.

For ease of understanding and illustration, the following examples are provided within the scope of the invention. These embodiments are also used to illustrate possible variations.

The complete disclosure of all applications, patents, and publications mentioned in the context is incorporated herein by reference and can be used to clarify an indefinite case.

Needless to say, in the known examples and additionally in the remainder of this summary, the percent reference data for the components present in the compositions is always the sum of the total arrivals of 100% and no more. All percentage data for the components present in the compositions are % by weight or percentage by weight. It is assumed that the temperature is measured in °C.

Example Example 1

50 g KOH (47%)

20 g butyrolactone

10 g Carbopol EZ 2

10 g Vestosint PA 2070

The KOH solution was mixed with butyrolactone. Then 10 g of Carbopol EZ 2 and 10 g of Vestosint PA 2070 were added while stirring. The mixture was stirred for another 2 hours.

Example 2

30 g KOH (47%)

20 g ethanol

10 g Carbopol EZ 2

10 g Vestosint PA 2070

This paste was prepared in the same manner as described in Example 1.

Example 3

60 g KOH (47%)

20 g methanol

10 g Carbopol EZ 2

10 g Vestosint PA 2070

This paste was prepared in the same manner as described in Example 1.

The etching paste is printed on the substrate by a screen printer. However, other methods of printing the etching paste as described above can also be used.

In order to obtain good results, the concentration of the etchant, the application amount of the etching paste, the etching time, and the temperature at the time of etching must be optimized to suit different layers and layer thicknesses.

Claims (17)

A method of selectively etching a polymer matrix comprising a silver nanotube comprising the steps of: a) applying an alkaline etch paste to the plastic substrate, b) heating, and c) cleaning the substrate. The method of claim 1, wherein the applied etching paste comprises an alkaline etchant selected from the group consisting of KOH, Ca(OH) ₂ , NaOH, TMAH, ethylenediamine, TMEH, SiOH, diethanolamine or triethanolamine. The method of claim 1, wherein the applied etching paste comprises a solvent selected from the group consisting of 1,4-butanediol, butyrolactone, ethanol or methanol. The method of claim 1, wherein the applied etching paste comprises 1,4-butanediol as a solvent. The method of any one of claims 1 to 4, wherein the applied etching paste comprises an organic and/or inorganic filler. The method of any one of claims 1 to 4, wherein the applied etching paste comprises organic polymer particles as a particulate filler. The method of any one of claims 1 to 4, wherein the applied etching paste is imprinted on the substrate. The method of any one of claims 1 to 4, wherein the etching paste is applied to the substrate by screen printing, especially rotary screen printing, or stencil printing. The method of any one of claims 1 to 4, wherein the etching paste is applied to the substrate by inkjet, in particular by micro-ejection on. The method of any one of claims 1 to 4 wherein the etching paste is dispensed onto the substrate. The method of any one of claims 1 to 4, wherein the etching paste is applied to the substrate by spraying or by slanting plate coating. The method of any one of claims 1 to 4 wherein the substrate is heated in step b) to a temperature of between about 40 and 140 ° C, preferably between about 80 and 120 ° C. . The method of any one of claims 1 to 4, wherein the substrate is heated at 80 ° C for 2 minutes in step b). The method of any one of claims 1 to 4, wherein the substrate is rinsed with a solvent after etching in step b) and the substrate is dried using dry air or a stream of nitrogen. The method of any one of claims 1 to 4, wherein the substrate is rinsed with deionized water after etching in step b) and the substrate is dried using dry air or a stream of nitrogen. The method of claim 1, wherein the plastic substrate is made of polyurethane or PEN [poly(ethylene naphthalate)] or PET (polyethylene terephthalate). The method of any one of claims 1 to 4 wherein the lines and structures are etched with a resolution of at least 100 μm.