Photosensitive solution for preparing metal film and method for preparing patterned metal conductive film through light induction

Abstract

The invention provides a photosensitive solution for preparing a metal thin film and a method for preparing a patterned metal conductive thin film through light induction, and belongs to the technical field of metal conductive thin films. The photosensitive solution for preparing the metal film comprises a soluble metal source, a photosensitive reagent, a tertiary amine additive, a surfactant, an organic acid salt additive and a solvent. The photosensitive solution provided by the invention is high in efficiency of preparing metal nanoparticles through light induction, and is suitable for preparing a metal conductive film through a light projection patterning technology of visible light. The method for preparing the patterned metal conductive thin film through light induction has the advantages of being simple in process, high in efficiency and integrated, and generation and patterning of the metal material can be achieved only through one-step light projection.

Description

Technical Field

[0001] The present invention relates to the technical field of metal conductive films, and in particular to a photosensitive solution for preparing metal films and a method for preparing patterned metal conductive films by light induction. Background Art

[0002] In the field of electronic devices, the integrated and patterned manufacturing of metal conductive films is crucial to improving actual production efficiency, reducing costs, improving product quality, and expanding the scope of application. Light projection metal patterning technology is to induce a light-sensitive solution into a patterned metal layer under light projection conditions. Compared with subtractive manufacturing methods such as laser cutting, light projection metal patterning has the advantages of simple process and high efficiency.

[0003] However, there are few studies on the integrated process of using light projection metal patterning technology to make flexible conductive films. This is because the range of metal materials it is applicable to is narrow and the preparation efficiency is limited by the photosensitive reagent. The ability of light-induced free radical reduction to synthesize metal nanoparticles is not as good as that of conventional common reducing agents such as sodium borohydride. Therefore, the light-induced method is usually used to synthesize metals that are easy to reduce, such as silver (Ag), which is the most widely used material, followed by gold (Au). Only a few studies have reported on copper (Cu) and palladium (Pd), and materials other than silver are usually prepared with low efficiency.

[0004] In addition, there are not many photoinitiators that can generate reducing free radicals. The commonly used ones are Irgacure 651 (α,α'-diphenylbenzil ketal), TPO (2,4,6-trimethylbenzoyl, diphenylphosphine oxide), benzophenone (BP), etc. The free radicals with reducing effects generated by them are dimethoxybenzyl radicals, diphenylphosphinoyl radicals, benzhydryl radicals (a kind of carbonyl radical), and α-aminoalkyl radicals. All of the above photoinitiators are ultraviolet (UV) initiators. Only one of the two free radicals generated by each molecule of initiator under light excitation has reducing properties, so the efficiency of reducing metal salts is low.

[0005] And UV light itself has safety issues in practical applications. UV generally uses mercury lamps, which generate heat when used, which poses a safety hazard in actual factory production, and the operation of ultraviolet rays needs to avoid direct exposure to the skin to prevent skin cancer.

[0006] In summary, there are currently few photosensitive solution systems that can be used for visible light projection metal patterning technology. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide a photosensitive solution for preparing a metal film and a method for light-induced preparation of a patterned metal conductive film. The photosensitive solution provided by the present invention has high efficiency in light-induced preparation of metal nanoparticles and is suitable for preparing metal conductive films by visible light light projection patterning technology.

[0008] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0009] The present invention provides a photosensitive solution for preparing a metal film, which comprises the following components in terms of molar concentration:

[0010]

[0011] and solvents;

[0012] The soluble metal source includes one or more of a soluble silver compound, a soluble palladium compound, a soluble gold compound and a soluble copper compound.

[0013] Preferably, the photosensitizer includes one or more of camphorquinone, thioacridone / iodonium salt system, eosin dye and ketocoumarin dye;

[0014] The tertiary amine auxiliary agent includes one or more of aliphatic tertiary amines, ethanolamine tertiary amines, tertiary amine type benzoic acid esters and active amines.

[0015] Preferably, the surfactant includes one or more of a sulfate surfactant, a quaternary ammonium salt surfactant, an amino acid surfactant and a non-ionic polymer surfactant;

[0016] The organic acid salt additive includes one or more of acetate, citrate, malate, gluconate and tartrate;

[0017] The solvent is an alcohol solvent.

[0018] The present invention provides a method for preparing a patterned metal conductive film by light induction, comprising the following steps:

[0019] Performing a first plasma treatment on the surface of the substrate to obtain an activated substrate;

[0020] Applying the above-mentioned photosensitive solution for preparing the metal thin film on the surface of the activated substrate, projecting a patterned visible light source onto the liquid-solid interface between the photosensitive solution and the activated substrate, inducing the photosensitive solution in the illuminated area to undergo an oxidation-reduction reaction, and obtaining a metal nanoparticle film on the surface of the substrate;

[0021] The metal nanoparticle film is subjected to a second plasma treatment to obtain a patterned metal conductive film.

[0022] Preferably, the power of the first plasma treatment and the second plasma treatment are independently 60 to 1200 W, and the time is independently 30 to 400 s.

[0023] Preferably, the amount of the photosensitive solution applied is 0.01 to 10 mL / cm 2 .

[0024] Preferably, the illumination intensity of the patterned visible light source is 10 to 10 6 mW / cm 2 ;

[0025] The temperature of the oxidation-reduction reaction is 10-120° C., and the time is 5 min-24 h.

[0026] Preferably, the thickness of the patterned metal conductive film is 20-200 nm.

[0027] Preferably, after the second plasma treatment, the method further comprises performing chemical copper plating or electrolytic copper plating on the surface of the patterned metal conductive film to obtain a patterned metal conductive film containing a copper thickening layer;

[0028] The thickness of the copper thickening layer obtained by the chemical copper plating is 0.1 to 5 μm;

[0029] The thickness of the copper thickening layer obtained by copper electroplating is 0.1-10 μm.

[0030] Preferably, after the chemical copper plating or electroplating copper, the process further comprises chemical tin plating on the surface of the obtained copper thickening layer to obtain a patterned metal conductive film containing the copper thickening layer and the tin layer;

[0031] The thickness of the tin layer is 0.1-10 μm.

[0032] The present invention provides a photosensitive solution for preparing a metal film, which comprises the following components in terms of molar concentration: 0.001-5 mol / L of a soluble metal source; 0.01-1 mol / L of a photosensitizer; 0.01-1 mol / L of a tertiary amine auxiliary agent; 0.001-5 mol / L of a surfactant; 0.01-1 mol / L of an organic acid salt additive; and a solvent; the soluble metal source comprises one or more of a soluble silver compound, a soluble palladium compound, a soluble gold compound, and a soluble copper compound. In the present invention, the tertiary amine auxiliary agent is a hydrogen donor for the photosensitizer, and the free radicals generated by dehydrogenation can be used to reduce the metal compound. The present invention uses a tertiary amine auxiliary agent as a photosensitizer auxiliary agent, which can induce the photosensitizer to generate dual reducing free radicals under visible light conditions, greatly improving the efficiency of the photochemical reduction reaction. The present invention adds an organic acid salt additive, which can be adsorbed on the surface of metal nanoparticles. The metal nanoparticles generate a surface plasma resonance effect under visible light irradiation, which triggers the organic acid additive adsorbed on the surface of the metal nanoparticles to undergo a redox reaction with the metal salt, and the metal salt is reduced to a metal element, further accelerating the generation of metal nanoparticles. In the present invention, the surfactant prevents the aggregation of particles by coating the surface of the metal nanoparticles, and can control the growth of particles, thereby achieving the purpose of preparing small-sized nanoparticles. In addition, the photosensitive solution of the present invention has a wide range of applications and can be used to prepare conductive films of various metals such as silver, palladium, gold, copper, and tin.

[0033] The present invention provides a method for preparing a patterned metal conductive film by light induction. The method of the present invention has the advantages of simple process and integration. The light projection patterning technology belongs to additive manufacturing technology, that is, directly adding conductive materials on the substrate. Compared with subtractive manufacturing, the process is simple and efficient. Only one step of light projection is required to realize the generation and patterning of metal materials. Furthermore, the scheme of the present invention integrates light projection patterning technology, plasma treatment and copper plating technology, which is easy to realize integrated manufacturing from raw materials to conductive film products, and is a further development of existing technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A flow chart for the preparation of patterned metal conductive films prepared by light induction;

[0035] Figure 2 The SEM images of the silver nanoparticle films obtained in Example 1 and Comparative Examples 1 to 3;

[0036] Figure 3 Reaction mechanism for preparing metal nanoparticle films from photosensitive solutions;

[0037] Figure 4 The patterned metal conductive film image was prepared by light induction;

[0038] Figure 5 Results of plasma treatment of metal nanoparticle films to improve electrical conductivity;

[0039] Figure 6 Test results of improving the conductivity of metal film for chemical copper plating;

[0040] Figure 7 Silver samples with different patterns and samples after copper plating;

[0041] Figure 8 Different metal samples prepared by photoinduced patterning process. DETAILED DESCRIPTION

[0042] The present invention provides a photosensitive solution for preparing a metal film, which comprises the following components in terms of molar concentration:

[0043]

[0044] and solvents;

[0045] The soluble metal source includes one or more of a soluble silver compound, a soluble palladium compound, a soluble gold compound and a soluble copper compound.

[0046] The photosensitive solution for preparing a metal film provided by the present invention comprises a soluble metal source of 0.001 to 5 mol / L. In the present invention, the soluble metal source comprises one or more of a soluble silver compound, a soluble palladium compound, a soluble gold compound and a soluble copper compound. In the present invention, the soluble silver compound is preferably one or more of silver nitrate, silver oxalate, silver oxide, silver chloride, silver hexafluorophosphate and silver hexafluoroantimonate, more preferably one or more of silver nitrate, silver oxalate and silver hexafluorophosphate, and most preferably silver nitrate; when the soluble metal source is a soluble silver compound, the concentration of the soluble silver compound is preferably 0.01 to 2 mol / L, more preferably 1 mol / L.

[0047] In the present invention, the soluble palladium compound is preferably one or more of potassium chloropalladate, palladium chloride, palladium acetate, palladium sulfate and palladium nitrate, more preferably potassium chloropalladate and / or palladium chloride, most preferably potassium chloropalladate; when the soluble metal source is a soluble palladium compound, the concentration of the soluble palladium compound is preferably 0.001 to 1 mol / L, more preferably 0.01 to 0.1 mol / L, and further preferably 0.05 mol / L.

[0048] In the present invention, the soluble gold compound is preferably chloroauric acid and / or gold chloride, more preferably chloroauric acid; when the soluble metal source is a soluble gold compound, the concentration of the soluble gold compound is preferably 0.001 to 1 mol / L, more preferably 0.01 to 0.1 mol / L, and further preferably 0.08 mol / L.

[0049] In the present invention, the soluble copper compound is preferably one or more of copper sulfate, copper acetate, copper chloride and copper nitrate, more preferably copper sulfate and / or copper acetate, and further preferably copper sulfate; when the soluble metal source is a soluble copper compound, the concentration of the soluble copper compound is preferably 0.001 to 1 mol / L, more preferably 0.01 to 0.1 mol / L, and further preferably 0.06 mol / L.

[0050] The photosensitive solution for preparing a metal film provided by the present invention includes 0.01 to 1 mol / L of a photosensitive agent, preferably 0.05 to 0.1 mol / L, and more preferably 0.05 mol / L. In the present invention, the photosensitive agent preferably includes one or more of a visible light initiator camphorquinone, a thioacridone / iodonium salt system, an eosin dye, and a coumarin ketone dye. In the present invention, the thioacridone / iodonium salt system is preferably 4-methylthioacridone / diphenyliodonium salt or 4-methoxythioacridone / diphenyliodonium salt, and the coumarin ketone dye is preferably 3,3'-di(7-diethylamino)coumarin ketone or coumarin 343. In the present invention, the photosensitive agent is more preferably camphorquinone and / or eosin dye, and more preferably camphorquinone. The present invention controls the photosensitive agent in the above-mentioned amount, which can maximize the preparation efficiency of metal nanoparticles.

[0051] The photosensitive solution for preparing a metal film provided by the present invention comprises 0.01 to 1 mol / L of a tertiary amine auxiliary agent, preferably 0.02 to 0.15 mol / L, and more preferably 0.025 mol / L. In the present invention, the tertiary amine auxiliary agent comprises one or more of aliphatic tertiary amines, ethanolamine-type tertiary amines, tertiary amine-type benzoic acid esters and active amines. In the present invention, the aliphatic tertiary amine can be selected from triethylamine, the ethanolamine-type tertiary amine can be selected from one or more of triethanolamine, N-methyldiethanolamine, N,N-dimethylethanolamine and N,N-diethylethanolamine, the tertiary amine-type benzoic acid ester can be selected from one or more of ethyl 4-dimethylaminobenzoate (EDMAB), 2-ethylhexyl N,N-dimethylbenzoate and dimethylaminobenzoate, and the active amine can be selected from tertiary amine acrylate. In the present invention, the tertiary amine auxiliary agent is more preferably a tertiary amine type benzoate and / or an ethanol type tertiary amine, and is further preferably a tertiary amine type benzoate, specifically ethyl 4-dimethylaminobenzoate. In the present invention, the tertiary amine auxiliary agent is a photosensitizer auxiliary agent, which is a hydrogen donor for the photosensitizer, and the free radicals generated by dehydrogenation can be used to reduce the metal compound.

[0052] The photosensitive solution for preparing a metal film provided by the present invention comprises 0.001 to 5 mol / L of a surfactant, preferably 0.01 to 2 mol / L, and more preferably 0.02 to 1 mol / L. In the present invention, the surfactant preferably comprises one or more of a sulfate surfactant, a quaternary ammonium salt surfactant, an amino acid surfactant, and a nonionic polymer surfactant. In the present invention, the sulfate surfactant is preferably sodium dodecyl sulfate and / or sodium dodecylbenzene sulfonate, the quaternary ammonium salt surfactant is preferably hexadecyltrimethylammonium chloride and / or hexadecyltrimethylammonium bromide, the amino acid surfactant is preferably sodium N-lauroyl sarcosinate and / or sodium N-decanoyl sarcosinate (NDSS), and the nonionic polymer surfactant is preferably polyvinyl pyrrolidone (PVP) and / or polyvinyl alcohol. In the present invention, the surfactant is more preferably sodium N-decanoyl sarcosinate or polyvinyl pyrrolidone. When the surfactant is sodium N-decanoyl sarcosinate, the amount of sodium N-decanoyl sarcosinate is preferably 0.01-0.2 mol / L, more preferably 0.02-0.1 mol / L, and further preferably 0.03 mol / L; when the surfactant is polyvinyl pyrrolidone, the amount of polyvinyl pyrrolidone is preferably 0.001-5 mol / L, more preferably 0.01-2 mol / L, and further preferably 1 mol / L. In the present invention, the surfactant prevents the aggregation of the particles by coating the surface of the metal nanoparticles, and can control the growth of the particles, thereby achieving the purpose of preparing small-sized nanoparticles.

[0053] The photosensitive solution for preparing a metal film provided by the present invention includes 0.01 to 1 mol / L of an organic acid salt additive, preferably 0.02 to 0.15 M, and more preferably 0.025 M. In the present invention, the organic acid salt additive preferably includes one or more of acetate, citrate, malate, gluconate and tartrate, and the organic acid salt is preferably a sodium salt or a potassium salt. In the present invention, the organic acid salt additive is more preferably sodium citrate and / or sodium tartrate. In the present invention, the organic acid salt additive can cooperate with the surface plasmon resonance (LSPR) effect of metal nanoparticles under visible light irradiation to further reduce the metal compound, which can enhance the efficiency of light-induced preparation of metal conductive films.

[0054] The present invention adopts a combination of a photosensitizer, a tertiary amine auxiliary agent, and an organic acid salt additive, which can generate two (double) reducing free radicals, namely, a carbonyl free radical and an α-aminoalkyl free radical, under the induction of visible light, thereby greatly improving the efficiency of the photochemical reduction reaction. At the same time, the metal nanoparticles generate a surface plasma resonance effect under the irradiation of visible light, which triggers a reduction reaction of the metal salt on the surface of the nanoparticles, further accelerating the growth of the particles.

[0055] The photosensitive solution for preparing a metal film provided by the present invention further comprises a solvent. In the present invention, the solvent is preferably an alcohol solvent, more preferably one or more of methanol, ethanol, ethylene glycol, propanol, glycerol, isopropanol, n-butanol and isobutanol, further preferably ethylene glycol and / or glycerol, and ethylene glycol is preferred. The present invention uses an alcohol solvent as the solvent of the photosensitive solution, which has good solubility for each component.

[0056] In the present invention, the method for preparing the photosensitive solution for preparing the metal thin film preferably comprises the following steps:

[0057] The photosensitive solution for preparing the metal film is obtained by mixing a soluble metal source, a photosensitizer, a tertiary amine auxiliary agent, a surfactant, an organic acid salt additive and a solvent.

[0058] The present invention has no special requirements for the mixing method, and any mixing method known in the art may be used, such as stirring mixing.

[0059] The present invention provides a method for preparing a patterned metal conductive film by light induction, comprising the following steps:

[0060] Performing a first plasma treatment on the surface of the substrate to obtain an activated substrate;

[0061] Applying the above-mentioned photosensitive solution for preparing the metal thin film on the surface of the activated substrate, projecting a patterned visible light source onto the liquid-solid interface between the photosensitive solution and the activated substrate, inducing the photosensitive solution in the illuminated area to undergo an oxidation-reduction reaction, and obtaining a metal nanoparticle film on the surface of the substrate;

[0062] The metal nanoparticle film is subjected to a second plasma treatment to obtain a patterned metal conductive film.

[0063] The present invention performs a first plasma treatment on the surface of the substrate to obtain an activated substrate. In the present invention, the material of the substrate is preferably one or more of glass, polyester, polyimide, polyethylene, polymethyl methacrylate, soluble polytetrafluoroethylene, polydimethylsiloxane and polyacrylate. The present invention has no special requirements for the thickness of the substrate, and a film substrate or a plate substrate with a thickness well known in the art can be used.

[0064] In the present invention, the plasma equipment used for the first plasma treatment is preferably a vacuum plasma cleaner or an atmospheric plasma cleaner. In the present invention, the gas source used to generate plasma is one or more of air, nitrogen, hydrogen, oxygen, argon and helium, more preferably air. In the present invention, the gas source can be a single gas or a mixed gas. When the gas source is a mixed gas, the present invention has no special requirements for the composition ratio of the mixed gas. In the present invention, the flow rate of the gas source is preferably 50 to 500 mL / min -1 , more preferably 250 mL / min -1 .

[0065] In the present invention, the power of the first plasma treatment is preferably 60 to 1200 W, more preferably 90 to 300 W, and further preferably 180 W; the time of the first plasma treatment is preferably 30 to 400 s, more preferably 60 to 300 s, and most preferably 60 s. The present invention can clean and activate the substrate through the first plasma treatment, so that active groups such as hydroxyl, amine, and carboxyl groups with good affinity with metal materials are generated on its surface, thereby enhancing the adhesion of the metal film on the substrate.

[0066] After obtaining the activated substrate, the photosensitive solution for preparing the metal thin film is applied to the surface of the activated substrate, and a patterned visible light source is projected onto the liquid-solid interface between the photosensitive solution and the activated substrate to induce the photosensitive solution in the illuminated area to undergo an oxidation-reduction reaction, thereby obtaining a metal nanoparticle film on the surface of the substrate. In the present invention, the application amount of the photosensitive solution is preferably 0.01 to 10 mL / cm 2 , more preferably 0.1 to 1.0 mL / cm 2 , more preferably 0.15 mL / cm 2In the present invention, the application method is preferably drop coating.

[0067] In the present invention, the patterned visible light source projection technology uses visible light with digital light processing (DLP) function as a light source, which can project a pre-drawn pattern onto the liquid-solid interface of the photosensitive solution and the activated substrate, thereby inducing a redox reaction in the illuminated area.

[0068] In the present invention, the visible light source is preferably one of blue light, green light and red light, more preferably blue light. In the present invention, the illumination intensity of the patterned visible light source is preferably 10 to 10 6 mW / cm 2 , more preferably 40 to 300 mW / cm 2 , more preferably 300mW / cm 2 . In the present invention, the illumination time of the patterned visible light source (i.e., the time of the redox reaction) is preferably 5 min to 24 h, more preferably 20 min to 4 h, and further preferably 40 min. In the present invention, the temperature of the redox reaction is preferably 10 to 120°C, more preferably 20 to 80°C, and further preferably room temperature. The present invention induces a redox reaction in the illuminated area through light projection patterning to generate metal nanoparticles, forming patterned metal nanoparticles consistent with the pattern. In the present invention, the metal in the metal nanoparticle film preferably exists in a single substance form.

[0069] After the redox reaction, the present invention preferably washes the obtained metal nanoparticle film. In the present invention, the washing is preferably performed by rinsing with ethanol and water.

[0070] After obtaining the metal nanoparticle film, the present invention performs a second plasma treatment on the metal nanoparticle film to obtain a patterned metal conductive film. In the present invention, the power of the second plasma treatment is preferably 60 to 1200 W, more preferably 90 to 300 W, and further preferably 180 W; the time of the second plasma treatment is preferably 30 to 400 s, more preferably 60 to 300 s, and most preferably 300 s. Through the second plasma treatment, the present invention can remove the surfactant coated on the surface of the metal nanoparticles through plasma, and at the same time, cause the nanoparticles to fuse, thereby forming a continuous, uniform, and conductive metal film.

[0071] In the present invention, the thickness of the patterned metal conductive film is preferably 20 to 200 nm, and more preferably 50 to 100 nm.

[0072] In the present invention, after the second plasma treatment, it is also preferably included to perform chemical copper plating or electroplating on the surface of the patterned metal conductive film to obtain a patterned metal conductive film containing a copper thickening layer. In the present invention, the thickness of the copper thickening layer obtained by the chemical copper plating is preferably 0.1-5 μm, more preferably 0.5-2 μm; the present invention has no special requirements for the chemical copper plating method, and the thickness of the copper thickening layer can be achieved by using the chemical copper plating method known in the art. As a specific embodiment of the present invention, the chemical copper plating solution used in the chemical copper plating includes 15g / L of copper sulfate, 94g / L of potassium sodium tartrate, 20g / L of sodium hydroxide and 77mL / L of formaldehyde, and the solvent is deionized water. In the present invention, the temperature of the chemical copper plating is preferably room temperature, and the time is preferably 1-120min, more preferably 2-60min, and further preferably 2.5min.

[0073] In the present invention, the thickness of the copper thickening layer obtained by the copper electroplating is preferably 0.1 to 10 μm, more preferably 1 to 5 μm. The present invention has no special requirements for the copper electroplating method, and the copper electroplating method well known in the art can be used to make the thickness of the copper thickening layer meet the requirements. As a specific embodiment of the present invention, the copper electroplating solution used in the copper electroplating is commercially available, the copper electroplating temperature is room temperature, and the DC current density is 2 mA / cm 2 The electroplating time is 1 to 60 minutes, preferably 4.5 minutes.

[0074] The present invention thickens the metal conductive layer through the chemical copper plating or the electrolytic copper plating, thereby improving the conductive performance of the film.

[0075] In the present invention, after the chemical copper plating or electroplating copper, it also includes chemical tin plating on the surface of the obtained copper thickening layer to obtain a patterned metal conductive film containing a copper thickening layer and a tin layer. In the present invention, the thickness of the tin layer is preferably 0.1 to 10 μm, more preferably 1 to 5 μm. The present invention has no special requirements for the chemical tin plating method, and the chemical tin plating method well known in the art can be used to make the thickness of the tin layer meet the requirements. As a specific embodiment of the present invention, the source of the chemical tin plating solution used for the chemical tin plating is commercially available, the temperature of the chemical tin plating is room temperature, and the time is 1 to 300 s, more preferably 15 s.

[0076] As a specific embodiment of the present invention, the preparation flow chart of the light-induced patterned metal conductive film is as follows: Figure 1 shown.

[0077] The following is a detailed description of a photosensitive solution for preparing a metal film and a method for light-induced preparation of a patterned metal conductive film provided by the present invention in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0078] Example 1

[0079] The formula of the photosensitizing solution is as follows:

[0080]

[0081] The solvent is ethylene glycol.

[0082] Comparative Example 1

[0083] The formula of the photosensitizing solution is as follows:

[0084]

[0085] The solvent is ethylene glycol.

[0086] Comparative Example 2

[0087] The formula of the photosensitizing solution is as follows:

[0088]

[0089] The solvent is ethylene glycol.

[0090] Comparative Example 3

[0091] The formula of the photosensitizing solution is as follows:

[0092]

[0093] The solvent is ethylene glycol.

[0094] Test Example 1

[0095] The photosensitive solutions obtained in Example 1 and Comparative Examples 1 to 3 were applied to the surface of the polyester PET substrate at an application rate of 0.15 mL / cm 2 ; The above photosensitive solution was irradiated with blue light at room temperature with an illumination intensity of 300 mW / cm 2 The photoinduced synthesis time is 1 hour. The scanning electron microscope (SEM) photos of the silver nanoparticle films obtained in Example 1 and Comparative Examples 1 to 3 are as follows: Figure 2 shown. Figure 2 In the figure, A is the SEM image of Comparative Example 3, B is the SEM image of Comparative Example 2, C is the SEM image of Comparative Example 1, and D is the SEM image of Example 1.

[0096] from Figure 2 Scanning electron microscope photos show that the silver nanoparticles prepared by the four formulations are numerous and relatively dense. Figure 2 A) and Comparative Example 2 (corresponding to Figure 2In B), it can be seen that the particle size is larger when PVP is used as a surfactant, and NDSS surfactant is more conducive to the generation of small-sized nanoparticles; the advantage of PVP as a surfactant is that the nanoparticles are tightly connected, which is more conducive to conductive properties.

[0097] Figure 2 C (corresponding to Example 1) uses sodium citrate as an additive. On the one hand, it replaces PVP and NDSS as a surfactant. More importantly, sodium citrate can also cooperate with the surface plasmon resonance (LSPR) effect of silver nanoparticles under visible light irradiation to reduce silver ions.

[0098] Figure 2 In D (corresponding to Example 1), PVP and sodium citrate are used at the same time, and the obtained silver nanoparticle film is the most dense, the particle continuity is the best, and the coverage rate of the nanoparticles on the substrate is the highest. At the same time, the generated nanoparticles are small in size, which is more conducive to the subsequent plasma sintering to improve the conductivity. Therefore, by adding organic acid salt additives such as sodium citrate to the basic formula of the photosensitive solution containing a surfactant, light-induced ① free radical reduction of silver ions and ② surface plasmon resonance (LSPR)-induced additive reduction of silver ions can be achieved simultaneously, thereby more efficiently preparing a metal conductive film with better performance.

[0099] The reaction mechanism of preparing metal nanoparticle films with photosensitive solutions is shown in Figure 3 , Figure 3 (A) is the reaction mechanism of the photoinduced reduction of silver ions by camphorquinone (CQ) and its auxiliary agent ethyl 4-dimethylaminobenzoate (EDMAB) to prepare silver nanoparticles, and (B) is the redox reaction mechanism of sodium citrate and silver ions under light conditions. Figure 3 As shown in (A), the photosensitizer camphorquinone CQ and its auxiliary EDMAB can generate two reducing free radicals under blue light irradiation. Figure 3 As can be seen from (B), sodium citrate further reduces silver ions, thereby enhancing the efficiency of light-induced preparation of metal conductive films.

[0100] It should be noted that:

[0101] ① Figure 3(A) shows the redox reaction between the photosensitizer and its auxiliary agent and the metal ion under light. The mechanism is that the photosensitizer is excited under light to extract the hydrogen atom in the auxiliary agent (the photosensitizer auxiliary agent is therefore also called a hydrogen donor), thereby generating two types of reducing free radicals, namely, carbonyl free radicals and α-aminoalkyl free radicals. This mechanism is not only applicable to camphorquinone (CQ) and its auxiliary agent 4-dimethylaminobenzoic acid ethyl ester (EDMAB), but also to other photosensitizers and auxiliary agents that can generate the same type of reducing free radicals, including but not limited to eosin dye, N-methyldiethanolamine, triethanolamine, etc.;

[0102] ② Figure 3 The redox reaction under visible light irradiation shown in (B) is not limited to occurring only between sodium citrate and metal ions. Its mechanism is that metal nanoparticles undergo a localized plasma resonance effect under visible light irradiation. Under the plasma-mediated effect, the redox reaction between the organic acid salt additives (including but not limited to sodium citrate, sodium acetate, sodium malate, etc.) adsorbed on the surface of the particles and the metal ions can be induced and catalyzed, thereby producing more metal elements, promoting the growth of metal nanoparticles, and thereby improving the preparation efficiency of metal nanoparticle films.

[0103] Example 2

[0104] The method for preparing a patterned metal conductive film by light induction comprises the following steps:

[0105] (1) According to the formula of Example 1, the raw materials are mixed to obtain a photosensitizing solution;

[0106] (2) Using polyester PET film as the substrate, a vacuum plasma cleaning machine was used to perform the first plasma treatment on the substrate surface. The gas source was air with a flow rate of 250 mL / min. -1 The power of the first plasma treatment is 180 W, the time is 60 s, and an activated substrate is obtained.

[0107] (3) Apply the photosensitive solution to the surface of the activated substrate at an application rate of 0.15 mL / cm 2 , and then use visible light (blue light) with digital light processing (DLP) as the light source to draw the pre-drawn graphics ( Figure 4 C) is projected onto the surface of the photosensitive solution and subjected to light synthesis at room temperature with a light intensity of 300 mW / cm 2 The time is 1h. The sample is rinsed with ethanol and water, and after drying, the sample is subjected to the second plasma treatment, the gas source is air, and the flow rate is 250mL / min -1 The power of the first plasma treatment is 180W, the time is 60s, and the obtained Figure 4 The patterned metallic silver circuit shown in A.

[0108] (4) Electroless copper plating is performed on the surface of the patterned metal silver circuit. The solvent of the electroless copper plating solution is deionized water, containing copper sulfate (15 g / L), potassium sodium tartrate (94 g / L), sodium hydroxide (20 g / L) and formaldehyde solution (77 mL / L). The copper plating is performed at room temperature for 2.5 min to obtain a patterned circuit containing a copper thickening layer, such as Figure 4 As shown in B and D.

[0109] Figure 4 This is a picture of patterned metal conductive film prepared by light-induced polymerization. Figure 4 In the figure, A is a patterned metal silver circuit prepared on a polyester (PET) film (the green background is the desktop where the sample is placed), B is a patterned circuit containing a copper thickening layer prepared on a PET film (the green background is the desktop where the sample is placed), C is the corresponding light projection pattern during the preparation process, and D is a patterned circuit containing a copper thickening layer prepared on a PET film (handheld actual picture).

[0110] Example 3 Plasma treatment of metal nanoparticle films to improve conductivity

[0111] The silver nanoparticle film was prepared in the same manner as in Example 1, except that the photoinduced synthesis time was extended to 90 min. The SEM image of the obtained silver nanoparticle film is shown in FIG. Figure 5 As shown in A. It can be seen that as the light-induced synthesis time increases, the particle size of the silver nanoparticles increases significantly.

[0112] Based on the obtained silver nanoparticle film, an air plasma treatment at 180W for 60s was used to obtain a silver conductive film. The SEM image of the obtained silver conductive film is shown in FIG. Figure 5 As shown in B. It can be seen that after plasma treatment, the boundaries of the independent silver nanoparticles are melted and connected to form an obvious sintering neck, and a continuous conductive path is formed between the particles, thereby enhancing the conductivity of the silver particle layer.

[0113] The conductivity of the samples was changed by changing the power of plasma treatment (maintained for 60 seconds). Figure 5 As shown in C. It can be seen that if a lower power plasma treatment is used, the conductivity of the obtained sample decreases.

[0114] The conductivity of the obtained samples was changed by changing the photoinduced synthesis time (the plasma treatment power was 180 W and the treatment time was 60 s). Figure 5 As shown in D. It can be seen that the current plasma treatment process has a significant effect on improving the conductivity of silver samples with different synthesis times, and the metal film obtained after plasma treatment of samples with long synthesis time has better conductivity.

[0115] Figure 5 A graph showing the results of plasma treatment of metal nanoparticle films to improve conductivity. Figure 5 In the figure, A is the SEM photo of the silver nanoparticle film synthesized by light-induced synthesis, B is the SEM photo of the sample after plasma treatment, C is the conductivity change diagram of the sample after plasma treatment with different powers, and D is the conductivity change diagram of the sample after plasma treatment with different light-induced synthesis times.

[0116] Example 4: Chemical copper plating to improve the conductivity of metal films

[0117] The metal conductive film was prepared in the same manner as in Example 2, except that the time of light irradiation synthesis was changed. The square resistance of the obtained silver conductive film and the silver conductive film containing a copper thickening layer was as follows: Figure 6 As shown in A in the figure. It can be seen that the square resistance of the three silver samples with different synthesis time is greatly reduced after chemical copper plating, which are 0.35, 0.34 and 0.31Ω / □ respectively. This is because the metal layer is more dense after copper plating. Taking the light synthesis time of 20min as an example, the SEM image of the silver conductive film before copper plating is shown in Figure 6 As shown in C, the SEM image of the silver conductive film after copper plating is as follows Figure 6 As shown in D in the figure, the cross-sectional SEM image of the silver conductive film after copper plating is as follows Figure 6 As shown in E. It can be seen that the silver conductive film is more dense after copper plating, and the thickening of the metal layer increases its conductivity. The thickness of the metal layer after chemical copper plating is about 200nm.

[0118] The SEM photo of the silver conductive film after copper plating and the corresponding sample element analysis (EDS) are shown in the figure below: Figure 6 As shown in B, it can be seen that the sample contains Cu and Ag, indicating that chemical copper plating on silver is successful, and the oxygen (O) element mainly comes from the polyester PET film substrate.

[0119] The test results of chemical copper plating to improve the conductivity of metal films are shown in the figure Figure 6 shown. Figure 6 In the figure, A is the change in conductivity of the silver sample before and after copper plating with different photoinduced synthesis times, B is the SEM photo of the sample after copper plating (upper right) and the corresponding sample element analysis (EDS) diagram, C is the SEM photo of the sample before copper plating, D is the SEM photo of the sample after copper plating, and E is a cross-sectional view of the copper-plated metal film.

[0120] Example 5: Electroplating copper to thicken metal film and improve conductivity

[0121] A silver conductive film was prepared by referring to steps (1) to (3) of Example 2 (the difference is that the light projection pattern is different), and copper was electroplated on the silver conductive film. The copper plating solution was a purchased finished product (purchased from Yancheng Haofan New Energy Technology Co., Ltd.), and the current density used for copper electroplating was 2 mA / cm 2, time is 4.5min, room temperature conditions.

[0122] Silver samples with different patterns and samples after copper plating are shown in Figure 2. Figure 7 As shown in A and B in the figure. The SEM image and elemental analysis spectrum after copper electroplating are shown in Figure 7 As shown in C. It can be seen that the elemental analysis results of the sample after copper plating confirm that the copper electroplating is successful.

[0123] The SEM cross-sectional image of the sample after copper plating is shown in Figure 7 As shown in D in the figure. It can be seen that the thickness of the metal film increases to about 1 μm after copper electroplating, and the square resistance of the sample is 0.04 Ω / □, which is about 10 times higher than the conductivity of the chemical copper plating sample, indicating that the copper electroplating effect is good. The key to the success of copper electroplating lies in the light-induced synthesis of the silver conductive film and the enhanced conductivity after plasma treatment. In the current research, most of them adopt the method of preparing the silver film first and then chemically plating copper, and there are few direct copper electroplating. The main reason is that the prepared silver film has poor conductivity and cannot be used as an electrode for electroplating. The present invention solves this problem.

[0124] Example 6 Preparation of various metal films by light-induced patterning process

[0125] (1) A silver conductive film after chemical copper plating was prepared by referring to steps (1) to (4) of Example 2 (the difference is that the light projection pattern is different), and tin is further plated on the surface of the copper layer. The chemical tin plating solution is purchased directly from Dongguan Beichen Hardware Technology Co., Ltd., model HG078, and the chemical tin plating is performed at room temperature for 15 seconds.

[0126] The Ag-Cu-Sn sample prepared by photoinduced patterning process and its elemental analysis are shown in Figure 2. Figure 8 As shown in A in FIG. 1 , it can be seen that the corresponding Ag, Cu, and Sn components are detected, indicating that the preparation of the copper-plated and tin-plated metal conductive film on silver is successfully achieved by adopting the formula and process of the present invention.

[0127] (2) According to the formula of Example 1, the difference is that silver nitrate is replaced by potassium chloropalladate to obtain a photosensitive solution containing a Pd component.

[0128] Referring to the method of steps (1) to (4) of Example 2, a patterned metal palladium sample is prepared (the difference is that the metal in the photosensitive solution is different), and copper and tin are further plated on the surface of the patterned metal palladium sample. The obtained palladium copper and tin plated (Pd-Cu-Sn) sample and its elemental analysis diagram are as follows: Figure 8 As shown in B.

[0129] (3) According to the formula of Example 1, the difference is that silver nitrate is replaced by chloroauric acid and copper sulfate, respectively, to obtain a photosensitive solution containing Au component and a photosensitive solution containing Cu component, respectively.

[0130] Referring to steps (1) to (3) of Example 2, the photosensitive solution containing Ag, the photosensitive solution containing Au, the photosensitive solution containing Pd, and the photosensitive solution containing Cu of Example 1 were used to prepare patterned samples of single metals. Patterned samples of single metals silver, gold, palladium, and copper and their corresponding elemental analysis diagrams are shown in FIG. Figure 8 As shown in C.

[0131] It can be seen that the method for light-induced preparation of patterned metal conductive films provided by the present invention can prepare and is not limited to the preparation of patterned films of a single metal (such as silver, gold, palladium, copper, platinum) and multi-metal (silver-copper, palladium-copper, silver-copper-tin, palladium-copper-tin), etc., which fully demonstrates that the method of the present invention has a wide range of material applicability.

[0132] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A photosensitive solution for preparing a metal thin film, characterized in that: In terms of molar concentration, it includes the following ingredients: Soluble metal source 0.001~5mol / L; Photosensitizer 0.01~1mol / L; Tertiary amine additives: 0.01~1mol / L; Surfactant 0.001~5mol / L; Organic acid salt additive 0.01~1mol / L; and solvents; The soluble metal source includes one or more of a soluble silver compound, a soluble palladium compound, a soluble gold compound and a soluble copper compound.

2. The photosensitive solution for preparing a metal thin film according to claim 1, characterized in that: The photosensitizer includes one or more of camphorquinone, thioacridone / iodonium salt system, eosin dye and ketocoumarin dye; The tertiary amine auxiliary agent includes one or more of aliphatic tertiary amines, ethanolamine tertiary amines, tertiary amine type benzoic acid esters and active amines.

3. The photosensitive solution for preparing a metal thin film according to claim 1 or 2, characterized in that: The surfactant includes one or more of sulfate surfactants, quaternary ammonium salt surfactants, amino acid surfactants and non-ionic polymer surfactants; The organic acid salt additive includes one or more of acetate, citrate, malate, gluconate and tartrate; The solvent is an alcohol solvent.

4. A method for preparing a patterned metal conductive film by light induction, characterized in that: The following steps are involved: Performing a first plasma treatment on the surface of the substrate to obtain an activated substrate; Applying the photosensitive solution for preparing a metal thin film according to any one of claims 1 to 3 on the surface of the activated substrate, projecting a patterned visible light source onto the liquid-solid interface between the photosensitive solution and the activated substrate, inducing the photosensitive solution in the illuminated area to undergo an oxidation-reduction reaction, and obtaining a metal nanoparticle film on the surface of the substrate; The metal nanoparticle film is subjected to a second plasma treatment to obtain a patterned metal conductive film.

5. The method according to claim 4, characterized in that The power of the first plasma treatment and the second plasma treatment are independently 60 to 1200 W, and the time is independently 30 to 400 s.

6. The method according to claim 4 or 5, characterized in that: The amount of the photosensitive solution applied is 0.01-10 mL / cm 2 .

7. The method according to claim 4, characterized in that The illumination intensity of the patterned visible light source is 10 to 10 6 mW / cm 2 ; The temperature of the oxidation-reduction reaction is 10-120° C., and the time is 5 min-24 h.

8. The method according to claim 4, characterized in that The thickness of the patterned metal conductive film is 20-200 nm.

9. The method according to claim 4, characterized in that After the second plasma treatment, the method further comprises performing chemical copper plating or electrolytic copper plating on the surface of the patterned metal conductive film to obtain a patterned metal conductive film containing a copper thickening layer; The thickness of the copper thickening layer obtained by the chemical copper plating is 0.1 to 5 μm; The thickness of the copper thickening layer obtained by copper electroplating is 0.1-10 μm.

10. The method according to claim 9, characterized in that After the chemical copper plating or electroplating, the method further comprises chemically plating tin on the surface of the obtained copper thickening layer to obtain a patterned metal conductive film containing the copper thickening layer and the tin layer; The thickness of the tin layer is 0.1-10 μm.

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