Method for forming a conductive structure

Abstract

This invention provides a method for forming a conductive structure. [Solution] This disclosure provides a method for forming a conductive structure. The method includes the steps of i) applying a conductive ink composition onto a substrate, and ii) irradiating the applied conductive ink composition with an IR laser. The IR laser irradiation is performed with a wavelength of 800 nm to 1150 nm and a pulse duration of 100 femtoseconds to 5000 femtoseconds, and is operated with an absolute value of defocus Z offset in the range of 2 mm to 40 mm.

Description

[Technical Field]

[0001] The present disclosure provides a method for forming a conductive structure including a step of laser irradiation. [Background Art]

[0002] Conventionally, conductive structures for electronic circuits can be formed by photolithography, in which unnecessary portions of a metal layer are removed by etching to provide a desired pattern. However, photolithography typically involves high energy and water consumption, multiple manufacturing steps and a considerable amount of waste material.

[0003] As an alternative to photolithography, printing techniques such as pressure-controlled direct discharge and electrohydrodynamic (EHD) discharge have been researched and developed. In contrast to photolithography, this technique is an additive process rather than a subtractive process and has the advantage of generating less waste material. In general, a printing technique involves extruding an ink composition containing a solvent and metal particles from a nozzle onto the surface of a substrate, drying the printed ink composition to remove the solvent, and sintering the metal particles in the printed ink composition to form a continuous metal line that constitutes a wiring pattern.

[0004] Conventionally, drying and sintering processes are performed thermally, and the printed ink composition, together with the substrate carrying it, is subjected to sintering of metal particles at a high temperature (such as 150°C to 350°C) under single thermal heating. The application of such thermal sintering processes is limited by the thermal stability of the ink composition and the substrate, especially for materials with lower glass transition temperatures and / or decomposition temperatures such as flexible polymers and paper.

[0005] Considering the drawbacks of thermal sintering, photosintering has been developed to perform sintering locally at relatively low temperatures. In particular, laser sintering has attracted attention in recent years. However, since lasers are inherently concentrated energy sources, they must be handled carefully, otherwise defects such as material cracking, delamination, and melting may occur. Complex process control may be required to ensure sufficient sintering effect while minimizing heat accumulation. Some previous works have required multiple irradiations, sometimes using different light sources with different wavelengths. There is still a need in this field to provide methods to address these problems. [Overview of the project] [Problems that the invention aims to solve]

[0006] In view of the aforementioned technical challenges, this disclosure aims to provide a feasible method that can optimize the laser sintering process and produce a conductive structure with good appearance, resistivity, and adhesion to a substrate. [Means for solving the problem]

[0007] The object of this disclosure is a method for forming a conductive structure, i) Applying a conductive ink composition onto a substrate, ii) Irradiating the coated conductive ink composition with an IR laser. This is achieved by providing a method that includes, IR laser irradiation is performed with wavelengths of 800 nm to 1150 nm and pulse durations of 100 femtoseconds to 5000 femtoseconds. IR laser irradiation is controlled by the absolute value of the defocus Z offset in the range of 2 mm to 40 mm.

[0008] In one embodiment of the present disclosure, the IR laser irradiation is operated at an output of 0.1W to 100W.

[0009] In one embodiment of the present disclosure, the IR laser irradiation is operated at a repetition rate of 20 kHz to 2000 kHz.

[0010] In one embodiment of this disclosure, the IR laser irradiation is operated at a scanning speed of 0.1 mm / s to 5000 mm / s.

[0011] In one embodiment of the present disclosure, IR laser irradiation is operated with a hatch pitch of 1 μm to 100 μm.

[0012] In one embodiment of this disclosure, IR laser irradiation is performed in a single step with a single wavelength.

[0013] In one embodiment of the present disclosure, coating is carried out by pressure-controlled direct dispensing, electrohydrodynamic (EHD) dispensing, inkjet printing, aerosol printing, screen printing, flexographic printing, gravure printing, offset printing, or a combination thereof.

[0014] In one embodiment of the present disclosure, the conductive ink composition comprises metal particles, a binder, and a solvent.

[0015] In one embodiment of the present disclosure, the substrate is selected from the group consisting of Cu, Ag, Ti, Ti-Al-Ti laminates, glass, Al2O3, BaTiO3, AlN, TiO2, ZrO2, polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene flangylcarboxylate (PEF), polycarbonate (PC), poly(methyl methacrylate) (PMMA), cyclic olefin polymer (COP), fiber-reinforced composites, and combinations thereof.

[0016] To further illustrate the above-mentioned objectives, technical features, and advantages of this disclosure, this disclosure will be described in detail below with reference to several embodiments. [Modes for carrying out the invention]

[0017] Several embodiments of this disclosure are described in detail below. However, this disclosure can be embodied in various embodiments, and the scope of protection of this disclosure should not be limited to those described herein.

[0018] When used herein, expressions such as “a,” “the,” etc., as used herein and in the claims should include both singular and plural forms unless otherwise specified.

[0019] As used herein, terms such as “first,” “second,” etc., as used herein and in the claims, are used solely to distinguish between the elements or components described herein and do not imply any priority.

[0020] As used herein, the term “focus” refers to the point where incident light converges. In embodiments where two or more lenses or mirrors are used, “focus” should be interpreted as the “equivalent focus” resulting from the combination of these lenses or mirrors.

[0021] The method of this disclosure is described in detail below.

[0022] This disclosure provides a method for forming a conductive structure, comprising i) applying a conductive ink composition onto a substrate, and ii) irradiating the applied conductive ink composition with an IR laser.

[0023] The method for applying the conductive ink composition is not particularly limited and may be any method known in the art. For example, the conductive ink composition may be applied by pressure-controlled direct dispensing, electrohydrodynamic (EHD) dispensing, inkjet printing, aerosol printing, screen printing, flexographic printing, gravure printing, offset printing, or a combination thereof. In one embodiment of the present disclosure, the conductive ink composition is applied to a substrate by pressure-controlled direct dispensing. In another embodiment of the present disclosure, the conductive ink composition is applied to a substrate by electrohydrodynamic (EHD) dispensing.

[0024] After the conductive ink composition is applied to a substrate, it is further processed to form a conductive structure on the substrate. Since conductive ink compositions usually contain a solvent for facilitating handling, it is necessary to remove the solvent so that the conductive components (usually metal particles) in the conductive ink composition can be brought into contact with each other and further melt-integrated. These processes are generally referred to as "drying" and "sintering" processes. In the present disclosure, the drying and sintering processes are performed by IR irradiation using an IR pulse laser. In one embodiment, both the drying and sintering processes are completed in the same one-step IR laser irradiation process.

[0025] In IR laser irradiation, removing the solvent through evaporation brings the metal particles into contact with each other and forms necks that fuse and integrate the particles. On the other hand, some conductive ink compositions also contain a binder. In such embodiments, the binder can partially photodecompose and evaporate during IR laser irradiation, thus leaving a portion of residual binder that can contribute to binding and integrating the metal particles and binding the metal particles to the substrate.

[0026] In one embodiment of the present disclosure, IR laser irradiation is performed in one step at a single wavelength. This simplifies the laser sintering process compared to some previous works that require multiple irradiation steps.

[0027] The method of the present disclosure mainly utilizes IR laser irradiation to dry the solvent and sinter the conductive components (usually metal particles). To achieve the target drying and sintering performance, several operating parameters in the IR laser irradiation process can be considered and adjusted to obtain optimal results. These operating parameters are described in detail below.

[0028] In this disclosure, IR laser irradiation is performed at a wavelength of 800 nm to 1150 nm. Within this range, the solvent can be removed at an optimal evaporation rate, and if a binder is used, it can be partially evaporated or decomposed and left behind. As a result, conductive structures produced using an IR pulsed laser with a wavelength within the above range may have better appearance, resistivity, and adhesion to the substrate compared to those produced using a green pulsed laser or a UV pulsed laser, etc. Specific examples of such IR laser irradiation include those having wavelengths of 808 nm, 830 nm, 850 nm, 905 nm, 915 nm, 920 nm, 940 nm, 950 nm, 980 nm, 1030 nm, 1053 nm, 1060 nm, 1064 nm, or 1150 nm. In one embodiment of this disclosure, the IR laser irradiation has a wavelength of 1030 nm.

[0029] In this disclosure, IR laser irradiation is performed with pulse durations of 100 femtoseconds (fs) to 5000 femtoseconds (fs). Pulse duration is defined as the full width at half maximum (FWHM) of the laser pulse in the pulse energy-time diagram. Longer pulse durations, such as on the order of nanoseconds, have been found to be able to form a melt zone or cause thermal damage to the coated conductive ink composition or substrate. In one embodiment of this disclosure, the pulse duration can be 100 fs to 5000 fs, or 250 fs to 2500 fs, or 400 fs to 1000 fs. For example, the pulse duration may be within the range of 100fs, 150fs, 200fs, 300fs, 400fs, 500fs, 600fs, 700fs, 800fs, 900fs, 1000fs, 1200fs, 1500fs, 2000fs, 2500fs, 3000fs, 3500fs, 4000fs, 4500fs, or 5000fs, or any two of the values ​​described herein.

[0030] In this disclosure, IR laser irradiation is operated using an IR pulsed laser with an absolute value of defocus Z offset in the range of 2 mm to 40 mm. The defocus Z offset refers to the distance between the laser focal point and the first surface of the coated conductive ink composition, i.e., the surface of the coated conductive ink composition away from the substrate. If the focal point is precisely on the first surface, the value of the defocus Z offset is zero. On the other hand, if the laser strikes the first surface before converging to the focal point, the value of the defocus Z offset is defined as negative, and if the laser strikes the first surface after converging to the focal point, the value of the defocus Z offset is defined as positive. When the laser strikes the first surface, a laser spot is generated on the first surface. In this disclosure, by intentionally moving the first surface away from the focal point (hereinafter also referred to as the “offset approach”) and controlling the laser spot size and laser pulse fluence, satisfactory sintering performance can be provided while preventing thermal damage. In one embodiment of this disclosure, the absolute value of the defocus Z offset can be 2 mm to 35 mm, or 2 mm to 30 mm. For example, the defocus Z offset can be -30mm, -25mm, -20mm, -15mm, -10mm, -5mm, -4mm, -3mm, -2mm, 2mm, 3mm, 3.5mm, 4mm, 5mm, 10mm, 15mm, 20mm, 25mm, 27mm, 30mm, 35mm, or 40mm.

[0031] In one embodiment of this disclosure, IR laser irradiation is performed using an IR pulsed laser at an output of 0.1W to 100W, 0.1W to 20W, or 0.5W to 8W. The output is defined as the maximum energy (peak energy) in the pulse energy-time diagram. Higher output may increase the likelihood of thermal damage, while lower output may increase the likelihood of insufficient sintering.

[0032] In one embodiment of the present disclosure, IR laser irradiation is operated using an IR pulsed laser at repetition rates of 20 kHz to 2000 kHz, 30 kHz to 1500 kHz, or 50 kHz to 1200 kHz. Repetition rate refers to the number of laser pulses emitted per unit time. With a fixed total energy, a higher pulse repetition rate spreads the energy over more pulses, resulting in lower energy per pulse or lower output per pulse.

[0033] In one embodiment of the present disclosure, IR laser irradiation is operated using an IR pulsed laser at scanning speeds of 0.1 mm / s to 5000 mm / s, 10 mm / s to 1000 mm / s, and 30 mm / s to 600 mm / s. The scanning speed refers to the linear relative movement per unit time of the laser striking the first surface of the coated conductive ink composition. The scanning speed can be adjusted to tune the laser pulse fluence.

[0034] In one embodiment of the present disclosure, IR laser irradiation is operated using an IR pulsed laser with hatch pitches of 1 μm to 100 μm, 3 μm to 50 μm, and 5 μm to 20 μm. The hatch pitch refers to a set displacement after the laser has scanned one scan line and before scanning another scan line. This can be interpreted as the distance between two adjacent scan lines. Similarly, the hatch pitch can be adjusted to tune the laser pulse fluence.

[0035] To form a conductive structure, the method of this disclosure requires a conductive ink composition and a substrate. Suitable materials for the conductive ink composition and substrate are described in detail below.

[0036] A conductive ink composition generally comprises metal particles for imparting conductivity to a conductive structure manufactured by this method, and a solvent for dissolving or dispersing the metal particles. In one embodiment of this disclosure, the conductive ink composition comprises metal particles, a binder, and a solvent. The binder can be used to enhance the adhesion of the metal particles to each other and to the substrate.

[0037] The type of metal particles is not particularly limited and can be selected based on processability, conductivity, appearance, or availability. In one embodiment of this disclosure, silver is used. In addition, the size of the metal particles can be selected depending on the process conditions, for example, for optimal absorption of a light / heat source. In one embodiment of this disclosure, the average diameter of the metal particles may be in the nanoscale, for example, in the range of 20 nm to 400 nm, or 50 nm to 350 nm, or 100 nm to 160 nm. In one embodiment of this disclosure, the metal particles are silver nanoparticles having an average diameter in the range of 80 nm, 100 nm, 130 nm, 150 nm, 200 nm, or 300 nm, or between any two of the values ​​described herein. The average diameter of the silver nanoparticles can be measured by using a dynamic light scattering particle size analyzer.

[0038] The type of binder can be selected so as to partially evaporate or decompose under a given light / heat source. Examples of binders, but not limited to, include poly(vinyl acetate), poly(vinyl alcohol) (PVA), polydioxanone (PDO), polyacrylamide (PAM), poly(glycolic acid) (PGA), poly-(ε-caprolactone) (PCL), poly(L-lactic acid) (PLLA), polyurethane (PU), polyacrylate, polyvinylpyrrolidone (PVP), poly(vinyl alcohol-coethylene), polyethylene glycol (PEG), poly(tetramethylene ether) glycol (PTMEG), ethylcellulose (EC), cellulose acetate, hydroxypropyl methylcellulose (HPMC), polyvinyl butyral (PVB), and combinations thereof. In more specific embodiments, the binder is selected from the group consisting of polyurethane (PU), polyacrylate, polyvinylpyrrolidone (PVP), ethylcellulose (EC), cellulose acetate, and hydroxypropyl methylcellulose (HPMC). The aforementioned binders can be used alone or in combination.

[0039] The type of solvent can be selected to ensure sufficient dissolution or dispersion of other components of the conductive ink composition, and to obtain an optimal evaporation rate under a given laser light source. The solvent can be used as a single-component solvent or as a mixed solvent of two or more components. In one embodiment of the present disclosure, the solvent is selected from the group consisting of alkoxy alcohols or alkoxy esters, such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, polyethylene glycol monomethyl ether, ethylene glycol monopropyl ether, diethylene glycol monopropyl ether, ethylene glycol monobutyl ether (also called butyl carbitol), triethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, and diethylene glycol mono-2-ethylhexyl ether. In one embodiment of the present disclosure, the solvent may have a boiling point in the range of 160°C to 270°C, for example, between 160°C, 170°C, 200°C, 230°C, 250°C, or 270°C, or any two of the values ​​described herein. In one embodiment of the present disclosure, the solvent does not contain polyols and / or water.

[0040] In embodiments in which the conductive ink composition comprises metal particles, a binder, and a solvent, the amount of metal particles can be in the range of 20 wt% to 95 wt%, 20 wt% to 75 wt%, or 25 wt% to 70 wt%, based on the total weight of the conductive ink composition; the amount of binder can be in the range of 0.1 wt% to 20 wt%, 2.5 wt% to 18 wt%, or 3 wt% to 15 wt%, based on the total weight of the conductive ink composition; and the amount of solvent can be in the range of 4.9 wt% to 79.9 wt%, 10 wt% to 75 wt%, or 25 wt% to 65 wt%, based on the total weight of the conductive ink composition. Furthermore, the amount of binder, based on the total weight of the binder and metal particles, can be in the range of 4 wt% to 45 wt%, 4.5 wt% to 40 wt%, or 5 wt% to 35 wt%.

[0041] In one embodiment of the present disclosure, the conductive ink composition may further include optional components to adapt or improve the physical properties, chemical properties, or processability of the conductive ink composition. Examples of optional components include, but are not limited to, additives such as adhesion promoters, coupling agents, rheology modifiers, dispersants, and surfactants.

[0042] In this disclosure, the material of the substrate is not particularly limited, as long as it can withstand the energy of the light / heat source used in the IR laser irradiation step. In one embodiment of this disclosure, the substrate may be Cu, Ag, Ti, Ti-Al-Ti laminate, glass, Al2O3, BaTiO3, AlN, TiO2, ZrO2, polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene flangylcarboxylate (PEF), polycarbonate (PC), poly(methyl methacrylate) (PMMA), cyclic olefin polymer (COP), fiber-reinforced composite, or a combination thereof.

[0043] Exemplary materials and preparations of conductive ink compositions and substrates are provided in the following Examples section. [Examples]

[0044] Preparation of materials [Preparation example PE1] A 20 wt% PVP solution was prepared using an overhead mechanical stirrer in a 1 L container with a 4C coolant jacket. First, 240 g of butyl carbitol (available from Alfa Chemistry) was added to the container. 60 g of polyvinylpyrrolidone (PVP) (available from Thermo-Fischer) was weighed into a tray. To prevent aggregation of PVP, 10 g of PVP was slowly added every 10 minutes until a total of 60 g of PVP was present in the solution. The solution was stirred for 4 hours until the PVP was completely dissolved.

[0045] 20 g of silver nanoparticle slurry (SDU-005, available from DOWA) was weighed into a vial. Then, a total of 10.2 g of the 20 wt% PVP solution prepared above was added to the vial in stages and mixed using a mixer (model number: ARE-500; available from Thinky). The steps were: adding 1 g of PVP solution and mixing at 1000 rpm for 60 seconds twice; adding 2 g of PVP solution and mixing at 1000 rpm for 60 seconds twice; and adding 7.2 g of PVP solution and mixing at 1000 rpm for 60 seconds twice. After the addition and mixing steps were completed, a conductive ink composition was obtained.

[0046] conductive structure Electrohydrodynamic (EHD) dispensing is performed to apply the conductive ink composition onto a substrate. The conductive ink composition prepared in Preparation Example PE1 is applied to a glass substrate to form parallel wiring lines on the substrate. The nozzle used has an inner diameter of 25 μm and an outer diameter of 55 μm and is positioned at a distance of 100 μm from the substrate. The conductive ink composition is filled and then pumped through the nozzle while the substrate is moved at a speed of 100 mm / s, driven by a voltage of 1 kV.

[0047] After applying the conductive ink composition to the substrate, irradiation is performed at each wavelength using a laser micromachining system (available from CohPros), while the operating parameters are changed according to the examples and comparative examples.

[0048] Test method [Bulk Resistance] The bulk resistivity of a single wiring line on a substrate is tested using a standard four-probe method. A source meter (Keithley 2400, available from Keithley Instruments) is used for the measurement. A fixed current of 0.5 mA is applied, and the real-time voltage drop across the wiring line is measured. The bulk resistivity is then calculated according to the following formula and reported in μΩ·cm units. Bulk resistivity = R × A / L (In the formula, R is the line resistance of the wiring line, L is the length of the wiring line. A is the cross-sectional area of ​​the wiring line (determined by Sensofar S neox).

[0049] [Adhesiveness] A pattern of 10 parallel wiring lines on a glass substrate will be used as a test specimen, and the adhesion of the wiring lines to the substrate will be evaluated by performing a modified cross-hatch tape test according to ASTM D3359.

[0050] First, make a first cut at a 90° angle to the lines through 10 parallel lines. Next, create a second cut through 10 parallel lines, parallel to the first cut and 10mm away from it, and cut these into 10 line segments. Then, create a third cut parallel to the second cut and 10mm away from it, generating another 10 line segments. Repeat the cutting process until a grid of 10 x 10 line segments is created. Then, soft brush the grid to remove debris generated from the cuts.

[0051] Place the tape (3M 610 tape, available from 3M) on the grid and press it smoothly to ensure uniform contact with the line segments. This can be confirmed by the uniform color tone of the contact area. Then, within 90 seconds of applying the tape, remove it by folding the tape 180° in the direction of the line segments (perpendicular to the cutting direction) and pulling it off.

[0052] The sample is then examined under an optical microscope (LSM900, available from Zeiss). Adhesion is evaluated according to the following criteria. 5B: All line segments remain intact, and no delamination occurs. 4B: Less than 5% of the line segments experience delamination. 3B: Less than 5% to 15% of the line segment undergoes delamination. 2B: Less than 15% to 35% of the line segment undergoes delamination. 1B: Less than 35% to 65% of the line segment undergoes delamination. 0B: More than 65% of the line segment undergoes delamination.

[0053] Example E1 and Comparative Examples CE1-CE2 Three different test specimens were prepared as described in the previous section, using an IR laser (Example E1), a green light laser (Comparative Example CE1), and a UV laser (Comparative Example CE2) for the irradiation step, respectively. During the irradiation step, the pulse duration was set to 500 femtoseconds, the defocus Z offset to 3 mm, the power to 2 W, the repetition rate to 100 kHz, the scanning speed to 50 mm / s, and the hatch pitch to 10 μm. The three test specimens were visually inspected and tested for bulk resistivity and adhesion according to the test methods described in the previous section. The results are summarized in Table 1.

[0054] [Table 1]

[0055] As shown in Table 1, fine wiring lines were fabricated by IR laser irradiation (Example E1). On the other hand, irradiation with a green light laser (Comparative Example CE1) or a UV laser (Comparative Example CE2) under the same operating conditions resulted in undesirable results, namely poor appearance and adhesion.

[0056] Examples E2-E4 and Comparative Examples CE3-CE4 A series of test specimens were prepared as described in the previous section, and the irradiation step was performed with a single IR laser having a wavelength of 1030 nm. In the irradiation step, the pulse duration was set to 500 femtoseconds, the power to 3.9 W, the repetition rate to 100 kHz, the scanning speed to 50 mm / s, the hatch pitch to 10 μm, and the defocus Z offset was varied for Examples E2-E4 and Comparative Examples CE3-CE4 according to Table 2. The test specimens were visually inspected and tested for bulk resistivity and adhesion according to the test methods described in the previous section. The results are summarized in Table 2.

[0057] [Table 2]

[0058] As shown in Table 2, at an output of 3.9W, if the IR laser strikes the first surface of the coated conductive ink composition, i.e., when the defocus Z offset = 0 (Comparative Example CE3), the wiring will burn. Adjusting the defocus Z offset to 1 mm (Comparative Example CE4) reduces damage due to burning, but the quality of the wiring line is still poor due to delamination from the substrate. It can be seen that satisfactory results are obtained when the defocus Z offset is adjusted to 2 mm or more (Examples E2-E4). In this case, the appearance, bulk resistivity, and adhesion of the wiring line are all good. This "offset approach" is important because, unlike the conventional "on-focus approach," desirable properties such as line resistivity and resolution are still acceptable.

[0059] Examples E5-E13 A series of test specimens were prepared as described in the previous section, and the irradiation step was performed with a single IR laser having a wavelength of 1030 nm. In the irradiation step, the pulse duration was set to 500 femtoseconds, while the defocus Z offset, power, repetition rate, scanning speed, and hatch pitch were varied for Examples E5 to E13 according to Table 3. The test specimens were visually inspected and tested for bulk resistivity and adhesion according to the test methods described in the previous section. The results are summarized in Table 3.

[0060] [Table 3]

[0061] As shown in Table 3, the results of Examples E5-E6 demonstrate that the "offset approach" is feasible with a negative defocus Z offset. Furthermore, the results of Examples E5-E13 show that operating parameters, including defocus Z offset, output, repetition rate, scan speed, and hatch pitch, can be adjusted to obtain optimal results. From these results, those skilled in the art will recognize that the method of this disclosure has great applicability.

[0062] While several embodiments are provided herein, they are merely illustrative examples and are not intended to limit the scope of protection of this disclosure. Those skilled in the art can develop various modifications based on the disclosed herein without departing from the principles thereof. The scope of protection of this disclosure is defined in the following claims.

Claims

1. A method for forming a conductive structure, i) Applying a conductive ink composition onto a substrate, ii) The process includes irradiating the coated conductive ink composition with an IR laser, The IR laser irradiation is performed with a wavelength of 800 nm to 1150 nm and a pulse duration of 100 femtoseconds to 5000 femtoseconds. The IR laser irradiation is operated by controlling the absolute value of the defocus Z offset in the range of 2 mm to 40 mm.

2. The method according to claim 1, wherein the IR laser irradiation is operated at an output of 0.1 W to 100 W.

3. The method according to claim 1, wherein the IR laser irradiation is operated at a repetition rate of 20 kHz to 2000 kHz.

4. The method according to claim 1, wherein the IR laser irradiation is operated at a scanning speed of 0.1 mm / s to 5000 mm / s.

5. The method according to claim 1, wherein the IR laser irradiation is operated with a hatch pitch of 1 μm to 100 μm.

6. The method according to claim 1, wherein the IR laser irradiation is performed at a single wavelength and in one step.

7. The method according to claim 1, wherein the coating is carried out by pressure-controlled direct discharge, electrohydrodynamic (EHD) discharge, inkjet printing, aerosol printing, screen printing, flexographic printing, gravure printing, offset printing, or a combination thereof.

8. The method according to claim 1, wherein the conductive ink composition comprises metal particles, a binder, and a solvent.

9. The substrate is Cu, Ag, Ti, Ti-Al-Ti laminate, glass, Al 2 O 3 , BaTiO 3 AlN, TiO 2 , ZrO 2 The method according to claim 1, selected from the group consisting of polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethylene flangylcarboxylate (PEF), polycarbonate (PC), poly(methyl methacrylate) (PMMA), cyclic olefin polymer (COP), fiber-reinforced composites, and combinations thereof.

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