Method for forming conductive wiring layer using light sintering and conductive wiring layer formed by using same

Abstract

The present invention provides a method for forming a conductive wiring layer using light sintering, and a conductive wiring layer formed by using same. According to an embodiment of the present invention, the method for forming a conductive wiring layer using light sintering includes: a conductive paste layer forming step of forming a conductive paste layer including conductive powder on a substrate; a mask arranging step of arranging a mask on the conductive paste layer; a main light irradiation step of irradiating light to the conductive paste layer by using the mask to form a photo-sintered region in which the conductive powder is photo-sintered; and a conductive wiring layer forming step of removing a non-photosintered region of the conductive paste layer so that a conductive wiring layer is formed in the photo-sintered region.

Description

Method for forming a conductive wiring layer using optical sintering and a conductive wiring layer formed using the same

[0001] The technical idea of ​​the present invention relates to a conductive wiring layer, and more specifically, to a method for forming a conductive wiring layer using optical sintering and a conductive wiring layer formed using the same.

[0002] The present invention relates to the Excellent Corporate Research Institute Promotion Project (ATC+) (Project No. 20014176, Project Unique No. 1415187319) carried out with support from the Korea Institute of Industrial Technology Planning and Evaluation with funding from the Ministry of Trade, Industry and Energy.

[0003] Wiring in conventional mobile communication components or semiconductor devices is typically formed through photolithography or damascene processes, which involve deposition, exposure, and development. Consequently, these processes require expensive equipment, such as deposition equipment, and additional materials, such as photoresist.

[0004] Alternatively, methods have been proposed to form wiring by performing high-temperature metallization using metal foil or conductive powder. In this case, the metallization process requires a specific energy source, and the process of metallizing the pattern is performed separately after forming the conductive powder pattern in the shape of the wiring. Furthermore, numerous processes, such as bonding, photolithography, and etching, are required, requiring additional equipment, requiring significant processing time and costs, and causing physical, chemical, and environmental problems. Furthermore, the metallization of the conductive powder requires high temperatures exceeding 600°C, which can lead to issues such as migration and diffusion to the substrate, and the generation of carbon dioxide during the process, which can cause environmental problems.

[0005] The technical problem to be achieved by the technical idea of ​​the present invention is to provide a method for forming a conductive wiring layer using optical sintering that can be performed at low temperatures and a conductive wiring layer formed using the method.

[0006] However, these tasks are exemplary and the technical idea of ​​the present invention is not limited thereto.

[0007] According to one aspect of the present invention, a method for forming a conductive wiring layer using optical sintering and a conductive wiring layer formed using the same are provided.

[0008] According to one embodiment of the present invention, the method for forming a conductive wiring layer using photo-sintering may include a conductive paste layer forming step of forming a conductive paste layer including conductive powder on a substrate; a mask placing step of placing a mask on the conductive paste layer; a main light irradiation step of irradiating light to the conductive paste layer using the mask to form a photo-sintered region in which the conductive powder is photo-sintered; and a conductive wiring layer forming step of removing an unsintered region in which the photo-sintered region of the conductive paste layer is not sintered so that a conductive wiring layer is formed in the photo-sintered region.

[0009] According to one embodiment of the present invention, after performing the step of forming the conductive paste layer, a preliminary drying step of drying the conductive paste layer may be further included.

[0010] According to one embodiment of the present invention, after performing the step of forming the conductive paste layer, a pressing step of pressing the conductive paste layer may be further included.

[0011] According to one embodiment of the present invention, after performing the step of placing the mask, a preliminary light irradiation step of irradiating light to the conductive paste layer using the mask to dry the conductive paste layer may be further included.

[0012] According to one embodiment of the present invention, a drying step of drying the conductive wiring layer may be further included.

[0013] According to one embodiment of the present invention, the step of forming the conductive paste layer may form the conductive paste on the substrate using screen printing, inkjet printing, gravure printing, or flexography.

[0014] According to one embodiment of the present invention, the main light irradiation step is 1 J / cm 2 30 J / cm 2 It can be performed using light having a pulse intensity in the range of 0.1 ms to 60 ms, a pulse gap in the range of 0.1 ms to 60 ms, and a pulse number in the range of 1 to 100.

[0015] According to one embodiment of the present invention, the main light irradiation step can be performed by at least one of a single shot irradiating light once, a multi-shot irradiating the same light multiple times, and a step shot irradiating light multiple times while changing the light.

[0016] According to one embodiment of the present invention, the step shot can be performed while changing the pulse intensity of the light.

[0017] According to one embodiment of the present invention, in the conductive wiring layer forming step, the removal of the unsintered region can be performed using distilled water or a basic solution containing sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or a mixture thereof as a developing solution.

[0018] According to one embodiment of the present invention, the conductive powder may include copper (Cu), silver (Ag), gold (Au), aluminum (Al), nickel (Ni), palladium (Pd), titanium oxide (TiO), or a combination thereof.

[0019] According to one embodiment of the present invention, the conductive powder may include a first powder having a first diameter in the range of 1 μm to 10 μm in an amount of 50 wt% to 90 wt%, and a second powder having a second diameter in the range of 20 nm to 1000 nm in an amount of 10 wt% to 50 wt%.

[0020] According to one embodiment of the present invention, the conductive powder may have at least one shape among a spherical shape, a square shape, a wire shape, a plate shape, a nanotube shape, a rod shape, and a whisker shape.

[0021] According to one embodiment of the present invention, the substrate may include a silicon substrate, a wafer, a glass substrate, a metal substrate, a ceramic substrate, a polymer substrate, a rigid substrate, a flexible substrate, a low-k film substrate, or a ceramic sheet substrate.

[0022] According to one embodiment of the present invention, the conductive paste forming the conductive paste layer may include the conductive powder, a dispersant, and a solvent.

[0023] According to one embodiment of the present invention, the conductive paste may further include a polymer resin for improving at least one of the properties of the conductive paste layer, such as adhesion to a substrate, shape retention, viscosity control, leveling, and photosensitivity.

[0024] According to one embodiment of the present invention, the polymer resin may include at least one of polyvinyl butyral, polyvinyl pyrrolidone, ethylene carbonate, polyvinyl alcohol, polyvinyl chloride, polyethylene, and polypropylene.

[0025] According to one embodiment of the present invention, the polymer resin may include a photosensitive polymer resin including at least one of an epoxy resin, an acrylate resin, a polyurethane resin, and a polyester resin.

[0026] According to one embodiment of the present invention, the polymer resin may include a photosensitive polymer resin including at least one of an oligomer, a monomer, and a photoinitiator.

[0027] According to one embodiment of the present invention, the conductive wiring layer can be formed using the method for forming a conductive wiring layer using the above-described optical sintering.

[0028] According to the technical idea of ​​the present invention, the method for forming a conductive wiring layer using optical sintering allows the use of substrates that may be damaged at high temperatures, since the formation of the conductive wiring layer is performed at low temperatures rather than high-temperature metallization. In addition, since a conductive paste layer is formed over the entire substrate and then metallization by optical sintering is used to form a pattern, the fixation and stability of the pattern can be superior compared to a method in which the pattern itself is screen-printed. In addition, since optical sintering is possible at a low temperature of 300°C or less for a short time, it is efficient and can reduce process time and cost. In addition, the conductive wiring layer has excellent straightness and surface roughness, so that the resistance of the wiring layer can be reduced and the skin effect can be minimized, and therefore, it can be applied to high-frequency circuits such as millimeter waves.

[0029] The method for forming a conductive wiring layer using optical sintering according to the present invention can be applied to various electronic industries, including displays, lighting, energy, and sensors. Furthermore, it can be applied to existing rigid substrates, as well as flexible substrates that can be bent, folded, or rolled. This allows for the creation of practical and portable electronic products. In particular, since optical sintering is possible at temperatures of approximately 300°C, it can be applied to polymer-based substrates that can be deformed at temperatures exceeding 300°C.

[0030] The method for forming a conductive wiring layer using optical sintering according to the present invention can be applied to radio frequency identification tags (RFID tags), near field communication (NFC) devices, solar cells, etc., and can be applied to disposable electronics, wearable electronics, deformable batteries, etc.

[0031] The effects of the present invention described above are illustrative, and the scope of the present invention is not limited by these effects.

[0032] FIG. 1 is a flowchart illustrating a method for forming a conductive wiring layer using optical sintering according to one embodiment of the present invention.

[0033] Figures 2 to 7 are cross-sectional views illustrating a method for forming a conductive wiring layer using optical sintering according to one embodiment of the present invention, step by step.

[0034] FIG. 8 is a schematic diagram illustrating optical sintering of conductive powder in a method for forming a conductive wiring layer using optical sintering according to one embodiment of the present invention.

[0035] FIG. 9 is a photograph of the surface of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to an embodiment of the present invention.

[0036] FIG. 10 is a scanning electron microscope photograph of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to an embodiment of the present invention.

[0037] Fig. 11 is a graph showing the surface roughness of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to one embodiment of the present invention.

[0038] FIG. 12 is a photograph of the surface of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to an embodiment of the present invention, according to the process steps.

[0039] Fig. 13 is a scanning electron microscope photograph of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to an embodiment of the present invention.

[0040] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Embodiments of the present invention are provided to more completely explain the technical idea of ​​the present invention to those skilled in the art. The following embodiments may be modified in various different forms, and the scope of the technical idea of ​​the present invention is not limited to the following embodiments. Rather, these embodiments are provided to more faithfully and completely convey the technical idea of ​​the present invention to those skilled in the art. Like reference numerals throughout this specification denote like elements. Furthermore, various elements and areas in the drawings are schematically drawn. Therefore, the technical idea of ​​the present invention is not limited by the relative sizes or intervals drawn in the attached drawings.

[0041] In this specification, a layer formed "on" another layer may refer to a layer formed directly above the other layer, or may refer to an intermediate layer or layers formed on another layer. It should be noted that the meanings of "upper" and "lower" in this specification are relative, and the direction upward from the substrate is described as "upper", and the direction downward is described as "lower."

[0042] Due to the trend of industrial diversification, printing technology is evolving with a variety of materials. Research is underway on photonics sintering, a method capable of forming circuit wiring layers without substrate deformation or deterioration. This photonics sintering method has been commercialized in some processes in the flexible electronics industry, and active research is underway in applications that can leverage the benefits of rapid sintering.

[0043] The optical sintering method can form a highly conductive wiring layer by irradiating ink or paste containing conductive powder with strong pulsed light to sinter at a high speed ranging from several ms to tens of ms, which is different from the conventional high-temperature and long-time sintering.

[0044] The present invention relates to optical sintering of inorganic and organic materials, and studies the changes in the electrical and physical properties of inorganic and organic materials due to optical sintering. Furthermore, when optically sintering printed compositions, process variables such as the intensity, amount, and time of optical energy, as well as differences in sintering degree, were analyzed. Accordingly, the influence of optical energy on the composition of inorganic and organic materials was analyzed, and an appropriate paste composition was derived. These results of the present invention can be applied to various electronic components, such as high-frequency band communication components.

[0045] Optical sintering offers the following advantages: Because it utilizes light for sintering, it enables high-speed, large-area sintering. It also allows for effective, selective sintering of required areas. It also allows for sintering at relatively low temperatures. Furthermore, the process is simple and ensures product uniformity.

[0046] The method for forming a conductive wiring layer using optical sintering according to the technical idea of ​​the present invention involves performing optical sintering locally on a region corresponding to the wiring layer using a mask to metallize the region, and removing the region not sintered due to being covered by the mask using a developer. Therefore, the patterning process and the metallization process can be performed in a single process.

[0047] FIG. 1 is a flowchart illustrating a method for forming a conductive wiring layer using optical sintering according to one embodiment of the present invention.

[0048] Referring to FIG. 1, a method (S1) for forming a conductive wiring layer using photo-sintering includes: a conductive paste layer forming step (S10) of forming a conductive paste layer including conductive powder on a substrate; a preliminary drying step (S20) of drying the conductive paste layer; a pressing step (S30) of pressing the conductive paste layer; a mask placing step (S40) of placing a mask having a pattern formed on the conductive paste layer; a preliminary light irradiation step (S50) of irradiating light onto the conductive paste layer using the mask to dry the conductive paste layer; a main light irradiation step (S60) of irradiating light onto the conductive paste layer using the mask to form a photo-sintered region in which the conductive powder is photo-sintered; a conductive wiring layer forming step (S70) of removing an unsintered region of the conductive paste layer so that a conductive wiring layer is formed in the photo-sintered region; and a drying step (S80) of drying the conductive wiring layer.

[0049] At least one of the above-mentioned preliminary drying step (S20), the above-mentioned pressing step (S30), the above-mentioned preliminary light irradiation step (S50), and the above-mentioned drying step (S80) is optional and may be omitted.

[0050] Figures 2 to 7 are cross-sectional views illustrating a method for forming a conductive wiring layer using optical sintering according to one embodiment of the present invention, step by step.

[0051] Referring to FIGS. 1 and 2, the conductive paste layer forming step (S10) can be performed by forming a conductive paste layer (20) including conductive powder on a substrate (10).

[0052] The conductive paste layer (20) can be formed on the substrate (10) using screen printing, inkjet printing, gravuring, or flexography. However, this is exemplary and the technical idea of ​​the present invention is not limited thereto.

[0053] The conductive paste layer (20) can be formed over the entire surface of the substrate (10) or locally.

[0054] The substrate (10) may include various substrates, and since the light sintering has a low process temperature of about 300°C or a high process temperature of about 1000°C, the light application time is very short, on the order of milliseconds, so it may include a substrate that is weak to high temperatures or a temperature-sensitive substrate. The substrate (10) may include, for example, a silicon substrate, a wafer, a glass substrate, a metal substrate, a ceramic substrate, a polymer substrate, a rigid substrate, a flexible substrate, a low-k film substrate, or a ceramic sheet substrate. However, this is an example, and the technical idea of ​​the present invention is not limited thereto.

[0055] The conductive paste forming the conductive paste layer (20) may include a conductive powder, a dispersant, and a solvent. The conductive paste may further include a polymer resin.

[0056] The conductive powder may include a metal or an oxide, for example, copper (Cu), silver (Ag), gold (Au), aluminum (Al), nickel (Ni), palladium (Pd), titanium oxide (TiO), or a combination thereof. The combination may include simple mixtures and alloys of the above-described metal materials. In addition, the conductive powder may include a core-shell material in which another metal has a core-shell structure, for example, a silver core-copper shell material, or a copper core-silver shell material.

[0057] The conductive powder may have a diameter capable of being photo-sintered, and for this purpose, it is preferable to have a diameter in the nano-millimeter range. The conductive powder may have a diameter in the range of, for example, 20 nm to 10 μm. The conductive powder may have a micro-sized diameter of, for example, 10 μm or less, and may have a first diameter in the range of, for example, 1 μm to 10 μm. Alternatively, the conductive powder may have a nano-sized diameter of, for example, 1000 nm or less, and may have a second diameter in the range of, for example, 20 nm to 1000 nm.

[0058] The conductive powder may be a mixed powder in which a first powder having a first diameter in the range of 1 μm to 10 μm and a second powder having a second diameter in the range of 20 nm to 1000 nm are mixed. The conductive powder may contain the first powder in the range of 50 wt% to 90 wt% and the second powder in the range of 10 wt% to 50 wt%.

[0059] The conductive powder may be a mixed powder comprising three or more powders having different diameters. In this way, by using a conductive powder comprising a mixture of powders having different diameters, the density of the formed conductive wiring layer can be increased.

[0060] The conductive powder may have various shapes, for example, at least one of a spherical type, an angular type, a wire type, a flake type, a nano tube type, a rod type, and a whisker type.

[0061] The dispersant can perform the function of uniformly dispersing solid particles such as the conductive powder in a solvent and preventing the solid particles from separating, agglomerating, or precipitating. The dispersant can reduce the interfacial tension between the inorganic powder and the polymer resin solution and can act through electrostatic repulsion or a steric effect. In particular, when the conductive powder has a diameter of nano-millimeters, it is preferable to include the dispersant. The dispersant can include various surfactants, and can include, for example, a saturated fatty acid or an unsaturated fatty acid, and can include, for example, a polycarboxylic acid-based material, an alkylamine-based material, a silicone-based material, and the like. The dispersant may include, for example, 2-Ethylhexyl 2-propenoate reaction products with ethylenediamine-ethylenimine polymer, a compound with polyethylene-polypropylene glycol monobutyl etherphosphate, a mixture of quaternary ammonium hydroxide, and the like.

[0062] The solvent may include an alcohol-based substance, an ether-based substance, or an ester-based substance, and may be polar or nonpolar. For example, the solvent may include a substance having a mean boiling point of 150°C or higher, such as diethylene glycol monoethyl ether acetate (ECA), ethylene glycol monobutyl ether acetate (BCA), alpha-terpineol, or hexylene glycol (HG).

[0063] The polymer resin may be added to improve at least one of the following properties: adhesion to the substrate of the conductive paste layer, shape retention, viscosity control, leveling, and photosensitivity. The polymer resin may include various polymer materials, such as high-polymer and synthetic polymer compound forms.

[0064] The polymer resin may include, for example, at least one of polyvinyl butyral (PVB), polyvinyl pyrrolidone (PVP), ethylene carbonate (EC), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyethylene (PE), and polypropylene (PP). Such a polymer resin may implement improved properties for adhesion of the conductive paste layer to the substrate, shape retention, viscosity control, and leveling.

[0065] Additionally, the polymer resin may include a photopolymer resin. The photopolymer resin may include various photosensitive materials and may include at least one of an oligomer, a monomer, and a photoinitiator.

[0066] The above oligomer may include, for example, at least one of an epoxy resin, an acrylate resin, a polyurethane resin, and a polyester resin.

[0067] The epoxy resin may include, for example, bisphenol A type epoxy, bisphenol F type epoxy, phenol novolac type epoxy, cresol novolac type epoxy, trisphenol methane type epoxy, biphenyl type epoxy, aliphatic type glycidyl ether, alicyclic epoxy, etc.

[0068] The above acrylate resin may include a resin synthesized using acrylate or methacrylate as a main monomer, may include acrylic acid and methacrylic acid or derivatives thereof, such as esters, nitriles, amides, etc., and may include various resins obtained by polymerizing olefin monomers. The above acrylate resin may include, for example, polymethyl methacrylate (PMMA), polyacrylic acid (PAA), polyacrylamide, polyacrylonitrile (PAN), butyl acrylate, 2-chloroethyl vinyl ether, etc.

[0069] The polyurethane resin may include, for example, ethylene glycol, propylene glycol, diethylene glycol, neopentyl glycol, 1,6-hexanediol, 1,4-butanediol, polytetramethylene glycol, polybutadiene diol, bisphenol A polyethoxydiol, triethylene propane, and the like.

[0070] The polyester resin may include, for example, carboxylated polyester acrylate, polyester triacrylate oligomer, polyester hexaacrylate oligomer, acid modified polyester acrylate, chlorinated polyester acrylate, etc.

[0071] The above monomer can react with other monomer molecules to form larger polymer chains or three-dimensional networks through a polymerization process. The above monomer has a molecular weight of 1,000 or less, and acts as a cross-linking agent and diluent for the oligomer, and can adjust the working viscosity while participating in the UV curing reaction to form part of the layer.

[0072] The above monomer may include various monomer materials and may include a material having a functional group in the range of 1 to 3.

[0073] The above monofunctional monomers include, for example, N-methoxymethyl methacrylamide, N-ethoxymethyl methacrylamide, N-alkoxymethyl methacrylamide, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl polyethoxy methacrylate, ethylcarbitol methacrylate, carbitol methacrylate, Tetrahydropropryl methacrylate, N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate, 3-(N,N-dimethylamino)propyl methacrylate, 3-(N,N-dimethylamino)propyl methacrylamide, N,N-diethylaminoethyl vinylether, 4-vinylpyridine methacrylamide, N-vinylpyrrolidone, N-vinyl caprolactam, acrylic morpholino morpholino), N,N,N-dimethylamino methacrylate, N,N-dimethyl methacrylamide, dicyclopentenyl methacrylate, dicyclopentenyloxyethyl methacrylate, hydrogenated dicyclopentenyl methacrylate, isobornyl methacrylate, cyclohexane-1,4-dimethylolmono methacrylate, o-phenyl·phenyloxyethyl methacrylate, o-phenyl·phenyloxyethyloxyethyl(meth) acrylate, phenyloxyethyl It may include phenyloxyethyl methacrylate, tribromphenyloxyethyl methacrylate, phenoxyethyl methacrylate, etc.

[0074] The above bifunctional monomers include, for example, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, 1,9-Nomendiol dimethacrylate, neopentyl glycol polypropoxy dimethacrylate, hydroxypivalic acid neopentyl glycol dimethacrylate, bisphenyl A polyethoxy dimethacrylate, bisphenol F polyethoxy dimethacrylate, polyethylene glycol dimethacrylate, It may include bis[methacryloyloxyethyl]hydroxyethyl isocyanurate, etc.

[0075] The above three functional monomers may include, for example, trimethylolpropane triacrylate (TMPTA), trimethylolpropane ethoxylate triacrylate (TMP3EOTA), ethoxylated trimethylolpropane triacrylate (TMP6EOTA), glyceryl propoxy triacrylate (G3POTA), and the like.

[0076] The photoinitiator can absorb energy from a light source, thereby inducing a photopolymerization reaction in the oligomer and the monomer. The photoinitiator can include various photoinitiators depending on the light used, such as short-wavelength light or long-wavelength light. For example, the photoinitiator can include, for example, an ultraviolet photoinitiator, a visible light photoinitiator, a near-infrared photoinitiator, a two-photon absorbing photoinitiator, a cationic photoinitiator, etc.The photoinitiator may be, for example, 4-methylbenzophenone, 4,4'-bis(diethylamino) benzophenone, 4-benzoyl-4'-methyldiphenylsulfide, ethyl phenlglyoxylate, ethyl o-benzoylbenzoate, 4-phenyl benzophenone, benzil dimethylketal, 2-ethylhexyl-4-dimethyl aminobenzoate, ethyl-4-dimethyl aminobenzoate, Hydroxy-2-methylphayl-propane-1-one, 1-hydroxycyclohexylphenylketone, sopropyl thioxanthone, 2,4-diethyl thioxanthone, 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, ethyl(2,4,6-trimethylbenzoyl)phenyl phosphinate It may include 2-benzyl-2-(dimethylamino)-1-[4-(morpholinyl)phenyl]-1-butanone, bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide, etc.

[0077] The proportions of the materials constituting the conductive paste may vary depending on the desired purpose. For example, in the conductive paste, the conductive powder may be 50 wt% to 90 wt%, the polymer resin may be 1 wt% to 10 wt%, the dispersant may be 0.1 wt% to 1 wt%, and the remainder may be the solvent. In addition, the oligomer may be 1 wt% to 10 wt%, the monomer may be 0.1 wt% to 1 wt%, and the photoinitiator may be 0.1 wt% to 1 wt%. However, this is merely exemplary and the technical idea of ​​the present invention is not limited thereto.

[0078] Referring to FIGS. 1 and 3, the preliminary drying step (S20) can be performed by drying the conductive paste layer (20).

[0079] In the above-described preliminary drying step (S20), the conductive paste layer (20) may be heated to a temperature ranging from 50°C to 100°C using a heater or the like to remove the solvent contained in the conductive paste layer (20). By this preliminary drying, the conductive paste layer (20) may be solidified. The preliminary drying may be performed by heat drying, and may be performed, for example, at a temperature ranging from 60°C to 100°C for 1 minute to 10 minutes. The preliminary drying may be performed, for example, by indirect hot air drying, direct hot air drying, far infrared drying, high-frequency heating, etc. However, this is merely exemplary, and the technical idea of ​​the present invention is not limited thereto. The above-described preliminary drying step (S20) is optional and may be omitted.

[0080] Referring to FIGS. 1 and 4, the pressing step (S30) can be performed by pressing the conductive paste layer (20) by using air pressure or a load.

[0081] By the above pressing step (S30), the internal pores of the conductive paste layer (20) can be reduced, the uniformity of height can be secured, and the thickness of the conductive paste layer (20) can be reduced. The pressing step (S30) is optional and can be omitted.

[0082] The conductive paste layer (20) can be physically flattened by the pressing described above. Alternatively, the conductive paste layer (20) can be physically flattened by dry leveling even when pressing is not performed.

[0083] The conductive paste layer (20) after performing the above pressing step (S30) may have various thicknesses that allow for photo-sintering, for example, may have a thickness of 20 μm or less, or may have a thickness in the range of 1 μm to 20 μm. However, this is exemplary and the technical idea of ​​the present invention is not limited thereto.

[0084] Referring to FIG. 1 and FIG. 5, the mask placement step (S40) can be performed by placing a mask (90) on a conductive paste layer (20).

[0085] The mask (90) may be placed in contact with the conductive paste layer (20) or may be placed spaced apart from it and not in contact. A pattern is formed on the mask (90), and the pattern can block light in a subsequent light irradiation step.

[0086] The mask (90) may be composed of glass, plastic, metal, paper, fiber, etc. The mask (90) may be a perforated type formed by forming an opening through which a material is removed, or a non-perforated type formed by forming a transparent area in the mask.

[0087] The above non-penetrating mask may be made of a transparent material, for example, a soda lime glass-based chrome (Cr) pattern mask, a quartz glass-based chrome pattern mask, a positive film patterning mask, etc.

[0088] The above-mentioned penetrating mask may be made of an opaque material, for example, a metal mask, a stainless steel mask, a ceramic sheet patterning mask, a film patterning mask, a paper patterning mask, etc.

[0089] However, this is exemplary and the technical idea of ​​the present invention is not limited thereto.

[0090] In addition, in the step of placing the mask (S30), the conductive paste layer (20) can be preheated to a temperature in the range of about 80°C to 120°C by being placed on a hot plate or the like.

[0091] Referring to FIG. 1 and FIG. 6, the preliminary light irradiation step (S50) and the main light irradiation step (S60) can be performed by irradiating light to the conductive paste layer (20) using a mask (90).

[0092] The above preliminary light irradiation step (S50) can be performed by irradiating light onto the conductive paste layer (20) using a mask (90) to dry the conductive paste layer (20). Accordingly, organic substances not removed from the conductive paste layer (20) in the preliminary drying step (S20) can be volatilized and removed. The light used in the preliminary light irradiation step (S50) can have a condition in which the conductive powder of the conductive paste layer (20) is not photo-sintered. The preliminary light irradiation step (S50) is optional and can be omitted.

[0093] The above main light irradiation step (S60) can be performed by irradiating light to the conductive paste layer (20) using a mask (90) to form a light-sintered area (22) in which the conductive powder is light-sintered.

[0094] The area of ​​the conductive paste layer (20) irradiated with light by the above-described photosintering can form a photosintered area (22). The area where light is blocked by the pattern of the mask (90) and not irradiated can form an unsintered area (24).

[0095] The above light can be obtained from various light sources, for example, an intense pulsed light (IPL) source can be used, and for example, a xenon flash lamp can be used.

[0096] For example, in the high-density pulse light source, some wavelength bands within the range of 100 nm to 1500 nm can be blocked, or only some wavelength bands can be selectively irradiated. In addition, selective light sources can be irradiated by cutting off / band passing through optical pulse filtering.

[0097] The above light is, for example, 1 J / cm 2 30 J / cm 2 It may have a pulse intensity in the range of 0.1 ms to 60 ms, a pulse gap in the range of 0.1 ms to 60 ms, and a pulse number in the range of 1 to 100 times. However, this is exemplary and the technical idea of ​​the present invention is not limited thereto.

[0098] The above light irradiation can be performed by at least one of a single shot in which light is irradiated once, a multi shot in which the same light is irradiated multiple times, and a step shot in which light is irradiated multiple times while changing the light. The step shot can be performed by changing the pulse intensity of the light, such as by increasing or decreasing it.

[0099] Referring to FIGS. 1 and 7, the conductive wiring layer forming step (S70) may be performed by removing the non-photosintered unsintered region (24) of the conductive paste layer (20) to form the conductive wiring layer (30). The non-sintered region (24) may be removed so that the substrate (10) is exposed. Accordingly, the remaining photosintered region (22) may form the conductive wiring layer (30).

[0100] The removal of the above-mentioned non-sintered region (24) can be performed using a developer, and this can be referred to as a development process. At this time, the photo-sintered region (22) is not removed by the developer.

[0101] The developer may be distilled water or an alkaline solution. The developer may include a metal salt, an alkaline rare earth metal salt, or a mixture thereof, for example, sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), potassium carbonate (K2CO3), or a mixture thereof. The developer may have a concentration in the range of 1 g / L to 10 g / L and a temperature in the range of 25°C to 40°C.

[0102] The above phenomenon can be performed using a wet method, for example, by applying, dipping, spraying, or puddle method. However, these are exemplary and the technical idea of ​​the present invention is not limited thereto.

[0103] The above application method can be performed by applying a developer on the conductive paste layer (20), developing it, and then removing the unsintered area (24) by washing it with distilled water or the like.

[0104] The above immersion method can be performed by immersing the structure of the substrate (10) and the conductive paste layer (20) in a container containing a developer, developing the structure, and then washing and removing the unsintered region (24) with distilled water or the like. Specifically, the immersion method can be performed by placing a developer containing only distilled water or a developer containing an alkaline substance in a container, and immersing the structure in the container. The cleaning can utilize ultrasonic cleaning, and the ultrasonic frequency can be in the range of 28 kHz to 300 kHz, the ultrasonic power can be in the range of 100 W to 1000 W, the temperature can be in the range of 25°C to 40°C, and the ultrasonic operating time can be in the range of 1 second to 5 minutes.

[0105] The spray method can be performed by spraying a developer through a nozzle onto the conductive paste layer (20) to develop it, and then washing and removing the unsintered region (24) with distilled water or the like. Specifically, the spray method can be performed by directly spraying a developer containing only distilled water or a developer containing an alkaline substance onto the structure using a nozzle. The nozzle can be flat or full cone, the temperature can range from 25°C to 40°C, the developing time can be 5 minutes or less, and the distilled water washing time can be 5 minutes or less. In addition, air drying to remove moisture can be performed within 5 minutes.

[0106] The above puddle method can be performed by providing a developer on a conductive paste layer (20), developing using surface tension, and then removing the unsintered area (24) by washing it with distilled water or the like.

[0107] However, this is exemplary and the technical idea of ​​the present invention is not limited thereto.

[0108] The above drying step (S80) may be performed by drying the conductive wiring layer (30). By drying, the developer remaining from the conductive wiring layer may be removed. The drying may be performed by heat drying, and may be performed, for example, at a temperature ranging from 60°C to 100°C for 1 to 10 minutes. The drying may be performed, for example, by indirect hot air drying, direct hot air drying, far infrared drying, high-frequency heating, etc. However, this is merely exemplary, and the technical idea of ​​the present invention is not limited thereto. The drying step (S80) is optional and may be omitted.

[0109] The conductive wiring layer (30) formed using the method for forming a conductive wiring layer using optical sintering according to the technical idea of ​​the present invention can be applied to various fields requiring a wiring layer. For example, it can be applied to mobile communication components, mobile communication modules, electrical devices, electronic devices, semiconductor devices, etc. In particular, the conductive wiring layer (30) can be applied as a wiring layer in a substrate that can be destroyed at high temperatures, such as a flexible printed circuit board.

[0110] FIG. 8 is a schematic diagram illustrating optical sintering of conductive powder in a method for forming a conductive wiring layer using optical sintering according to one embodiment of the present invention.

[0111] Referring to Fig. 8, the conductive powder (26) included in the conductive paste layer is individually separated before photo-sintering.

[0112] On the other hand, after performing photo-sintering, the conductive powders (26) undergo a sintering phenomenon on the surface to form a photo-sintered conductive powder sintered body (28). The light used in the photo-sintering can be used as metallization energy for the conductive powder (26). A conductive wiring layer (30) can be formed by the conductive powder sintered body (28).

[0113] Experimental example

[0114] Below, preferred experimental examples are presented to aid understanding of the present invention. However, the following experimental examples are provided solely to aid understanding of the present invention, and the present invention is not limited to the following experimental examples.

[0115] A conductive paste containing conductive powder, dispersant, and solvent was prepared.

[0116] In the above conductive paste, the conductive powder is silver (Ag) powder, and flake silver powder with a diameter of 7 μm or less, spherical silver powder with a diameter of 7 μm or less, and nano silver powder with a diameter of 300 nm or less were prepared.

[0117] The solvent was diethylene glycol monoethyl ether (ECA).

[0118] The dispersants were 2-propenoate reaction products with ethylenediamine-ethylenimine polymer and a compound with polyethylene-polypropylene glycol monobutyl etherphosphate.

[0119] Polyvinyl butyral (PVB) or polyvinyl pyrrolidone (PVP) was added as a polymer resin to some of the above conductive paste.

[0120] Epoxy or acrylate was added as a photosensitive polymer resin to some of the above conductive paste.

[0121] Table 1 is a table showing the materials and contents (weight%) constituting the conductive paste.

[0122] Separator plate type silver powder (7 μm or less) Spherical silver powder (7 μm or less) Nano silver powder (300 nm or less) Polymer resin solvent dispersant Experimental example 19000091 Experimental example 20900091 Experimental example 30090091 Experimental example 463270091 Experimental example 563027091 Experimental example 663027 Epoxy 4.54.51 Experimental example 763027 Acrylate 4.54.51 Experimental example 863027 PVB 4.54.51 Experimental example 963027 PVP 4.54.51

[0123] The above conductive paste was formed by mixing the above-described materials, then mixing at high speed and then mixing with a 3-roll mixer.

[0124] The above conductive paste was screen-printed onto a glass substrate to form a square conductive paste layer. The scraper speed was 50 mm / sec, the squeegee speed was 50 mm / sec, and the gap between the substrate and the screen was 1.2 mm.

[0125] The conductive paste layer was irradiated with light to perform photosintering. The light was irradiated with pulse intensities shown in the table below. The light was irradiated with single shots, multi-shots, and step shots.

[0126] The resistivity of the photo-sintered structure was measured using a four-point probe. The microstructure was observed using a scanning electron microscope. In addition, a cross-cut adhesion test was performed on the structure.

[0127] Results and Analysis

[0128] Hereinafter, with reference to Tables 2 to 5 and FIGS. 9 to 11, the characteristics of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to an embodiment of the present invention will be examined.

[0129] Table 2 shows the results of a cross-cut adhesion test of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to one embodiment of the present invention.

[0130] Tables 3 to 5 show the results of resistivity measurements of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to an embodiment of the present invention. Table 3 shows the single-shot results, Table 4 shows the multi-shot results, and Table 5 shows the step-shot results.

[0131] Classification Results Experimental Example 14B Experimental Example 24B Experimental Example 34B Experimental Example 45B Experimental Example 55B Experimental Example 64B Experimental Example 74B Experimental Example 85B Experimental Example 94B

[0132] Resistivity (μΩ cm) 5.5 J / cm 2 6.0 J / cm 2 6.5 J / cm 2 7.0 J / cm 2 Experimental Example 110.59.57.56.5 Experimental Example 219.017.515.5-Experimental Example 310.09.0--Experimental Example 420.016.514.011.0 Experimental Example 511.510.08.07.0 Experimental Example 611.58.57.0-Experimental Example 78.57.55.5-Experimental Example 811.59.58.57.5 Experimental Example 914.012.010.58.5

[0133] Resistivity (μΩ cm) 3.0 J / cm 2 3.0 J / cm per session 2 2 times 3.0 J / cm 2 3rd Experiment Example 1 - 8.09.0 Experiment Example 2 17.511.0 - Experiment Example 3 - 79.080.0 Experiment Example 4 13.511.5 Experiment Example 5 12.510.011.0 Experiment Example 6 80.0 - Experiment Example 7 80.080.0 - Experiment Example 8 19.014.014.0 Experiment Example 9 - 22.015.5

[0134] Resistivity (μΩ cm) 1.5 => 2.5 => 3.5 J / cm 2 3.0 => 3.25 => 3.5 J / cm 2 Experimental Example 17.57.0 Experimental Example 226.030.0 Experimental Example 319.519.0 Experimental Example 416.513.0 Experimental Example 510.511.5 Experimental Example 612.07.5 Experimental Example 718.510.0 Experimental Example 88.57.5 Experimental Example 99.59.5

[0135] FIG. 9 is a photograph of the surface of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to an embodiment of the present invention.

[0136] FIG. 10 is a scanning electron microscope photograph of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to an embodiment of the present invention.

[0137] Figures 9 and 10 show photographs of the structure of Experimental Example 5. Surface photographs of after printing, single shot, multi shot, and step shot, as well as surface microstructure observed with a scanning electron microscope, are shown. Here, the single shot was 7.0 J / cm 2 and the multi-shot was 3.0 J / cm 2 It was 3 times, and the step shot was 3.0 => 3.25 => 3.5 J / cm 2 was the condition.

[0138] Fig. 11 is a graph showing the surface roughness of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to one embodiment of the present invention.

[0139] Analysis of the cross-cut adhesion test results shows that all cases exhibit 4B or higher. In addition, the mixed powder of Experimental Example 4 exhibited the greatest adhesion, followed by the polymer-mixed cases of Experimental Examples 5 and 8, and then the single powder.

[0140] The resistivity varied depending on the shape, size, and mixing of the silver powder, and it was found that in order to implement a resistivity of less than 30 μΩ cm, it was possible for the silver powder to be in the form of a plate, nanopowder, spherical, and mixed form. The resistivity increased in the order of the plate, nanopowder, and spherical form of the silver powder. That is, since the plate-shaped silver powder of Experimental Example 1 showed the lowest resistivity, it is analyzed that the conductivity of the conductive wiring layer will be the highest. In addition, the plate-shaped and nano silver powder-mixed form of Experimental Example 5 also showed a relatively low resistivity.

[0141] Additionally, the resistivity varied depending on the light irradiation conditions, and it was found that single-shot, multi-shot, and step-shot were all possible to achieve a resistivity of less than 30 μΩ cm. Overall, low resistivity was observed in single-shot, and the resistivity decreased as the light pulse intensity increased.

[0142] Analysis of the microstructure shows that the particle size changes due to photo-sintering by single shot, multi-shot, and step shot, and that larger bonds are formed between particles.

[0143] When examining the surface roughness, Experimental Example 1 had a centerline average roughness (Ra) of 0.83 μm and a ten-point average roughness (Rz) of 3.68 μm, and Experimental Example 5 had a centerline average roughness (Ra) of 0.77 μm and a ten-point average roughness (Rz) of 1.03 μm. Therefore, Experimental Example 5 exhibited more uniform surface roughness. Therefore, the case where nano silver powder is mixed can exhibit better surface characteristics.

[0144] For reference, in the graph of Fig. 11, the X-axis represents the distance in one direction of the experimental specimen on which surface roughness was performed, and there were a total of 2500 points. The total measured length was approximately 770 μm, and 1 point was approximately 0.3 μm.

[0145] FIG. 12 is a photograph of the surface of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to an embodiment of the present invention, according to the process steps.

[0146] Fig. 13 is a scanning electron microscope photograph of a photo-sintered structure formed using a method for forming a conductive wiring layer using photo-sintering according to an embodiment of the present invention.

[0147] In Figures 12 and 13, the surface shape and microstructure of the structure of Experimental Example 5 are shown. In addition, similar results to Experimental Example 5 were obtained in other experimental examples.

[0148] Referring to Fig. 12, the surface topography immediately after printing, immediately after photo sintering, and immediately after developing of a conductive paste layer formed over the entire substrate is shown. After photo sintering of the conductive paste layer formed over the entire substrate, it can be seen that a relatively bright photo sintered region (22) and a relatively dark unsintered region (24) are formed. Immediately after developing, i.e., after removing the unsintered region, an exemplary conductive wiring layer composed of a patterned photo sintered region can be formed.

[0149] Referring to Figure 13, the microstructure of the surface and cross section of the photo-sintered structure immediately after printing and immediately after photo-sintering are shown. Immediately after printing, individualized silver powders were observed on the surface and cross section, and immediately after photo-sintering, it was observed that the silver powders formed a sintered body through photo-sintering.

[0150] In 5G applications utilizing high-frequency bands, controlling the roughness of the electrode surface is crucial. As the current frequency increases, most of the current flows closer to the conductor surface, resulting in transmission loss. This is known as the skin effect and skin depth. When verifying the controllability of surface roughness related to the transmission loss required in high-frequency bands, surface conditions can vary depending on the powder mixture.

[0151] It will be apparent to a person skilled in the art to which the technical idea of ​​the present invention pertains that the technical idea of ​​the present invention described above is not limited to the above-described embodiments and the attached drawings, and that various substitutions, modifications, and changes are possible within a scope that does not depart from the technical idea of ​​the present invention.

Claims

1. A conductive paste layer forming step of forming a conductive paste layer containing conductive powder on a substrate; A mask placement step of placing a mask on the conductive paste layer; A main light irradiation step of irradiating light onto the conductive paste layer using the mask to form a light-sintered region in which the conductive powder is light-sintered; and Including a conductive wiring layer forming step of removing a non-photosintered unsintered area of ​​the conductive paste layer so that a conductive wiring layer is formed in the photosintered area. Method for forming a conductive wiring layer using optical sintering.

2. In paragraph 1, After performing the step of forming the conductive paste layer, Further comprising a pre-drying step of drying the conductive paste layer, Method for forming a conductive wiring layer using optical sintering.

3. In paragraph 1, After performing the step of forming the conductive paste layer, Further comprising a pressing step of pressing the conductive paste layer, Method for forming a conductive wiring layer using optical sintering.

4. In paragraph 1, After performing the steps of placing the above mask, Further comprising a preliminary light irradiation step of drying the conductive paste layer by irradiating light onto the conductive paste layer using the mask. Method for forming a conductive wiring layer using optical sintering.

5. In paragraph 1, Further comprising a drying step of drying the conductive wiring layer, Method for forming a conductive wiring layer using optical sintering.

6. In paragraph 1, The step of forming the conductive paste layer is: Forming a conductive paste on the substrate using screen printing, inkjet printing, gravure printing, or flexography, Method for forming a conductive wiring layer using optical sintering.

7. In paragraph 1, The above main light irradiation step is, 1 J / cm 2 30 J / cm 2 Performed using light having a pulse intensity in the range of 0.1 ms to 60 ms, a pulse gap in the range of 0.1 ms to 60 ms, and a pulse number in the range of 1 to 100. Method for forming a conductive wiring layer using optical sintering.

8. In paragraph 1, The above main light irradiation step is, Performed with at least one of a single shot that irradiates light once, a multi-shot that irradiates the same light multiple times, and a step shot that irradiates light multiple times while changing it. Method for forming a conductive wiring layer using optical sintering.

9. In paragraph 8, The above step shot is, Performed while changing the pulse intensity of the above light, Method for forming a conductive wiring layer using optical sintering.

10. In paragraph 1, In the above conductive wiring layer forming step, The removal of the above-mentioned unsintered area is performed by using a basic solution containing distilled water or sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate or a mixture thereof as a developing solution. Method for forming a conductive wiring layer using optical sintering.

11. In paragraph 1, The above conductive powder is, Containing copper (Cu), silver (Ag), gold (Au), aluminum (Al), nickel (Ni), palladium (Pd), titanium oxide (TiO), or a combination thereof. Method for forming a conductive wiring layer using optical sintering.

12. In paragraph 1, The above conductive powder is, A first powder having a first diameter in the range of 1 μm to 10 μm is included in an amount of 50 wt% to 90 wt%, A second powder having a second diameter ranging from 20 nm to 1000 nm, comprising from 10 wt% to 50 wt%, Method for forming a conductive wiring layer using optical sintering.

13. In paragraph 11, The above conductive powder is, Having at least one shape among spherical, square, wire-like, plate-like, nano-tubular, rod-like, and whisker-like, Method for forming a conductive wiring layer using optical sintering.

14. In paragraph 1, The above substrate is, Including a silicon substrate, wafer, glass substrate, metal substrate, ceramic substrate, polymer substrate, rigid substrate, flexible substrate, low-k film substrate, or ceramic sheet substrate, Method for forming a conductive wiring layer using optical sintering.

15. In paragraph 1, The conductive paste forming the above conductive paste layer is Comprising the conductive powder, dispersant, and solvent, Method for forming a conductive wiring layer using optical sintering.

16. In paragraph 15, The above conductive paste, Further comprising a polymer resin for improving at least one of the properties of the conductive paste layer, adhesion to the substrate, shape retention, viscosity control, leveling, and photosensitivity. Method for forming a conductive wiring layer using optical sintering.

17. In paragraph 16, The above polymer resin is, Comprising at least one of polyvinyl butyral, polyvinyl pyrrolidone, ethylene carbonate, polyvinyl alcohol, polyvinyl chloride, polyethylene, and polypropylene, Method for forming a conductive wiring layer using optical sintering.

18. In paragraph 16, The above polymer resin is, Comprising a photosensitive polymer resin comprising at least one of an epoxy resin, an acrylate resin, a polyurethane resin, and a polyester resin; Method for forming a conductive wiring layer using optical sintering.

19. In paragraph 16, The above polymer resin is, Comprising a photosensitive polymer resin comprising at least one of an oligomer, a monomer, and a photoinitiator; Method for forming a conductive wiring layer using optical sintering.

20. Formed using the method for forming a conductive wiring layer using optical sintering according to Article 1, Conductive wiring layer.

Images