Low solid packed mixed silver photocurable printing conductive ink and preparation method and printing method thereof

Abstract

The application discloses a low-solid-phase filling mixed silver photocuring printing conductive ink and a preparation method and a printing method thereof, relates to a photocuring printing conductive ink and a preparation method and a printing method thereof. The application solves the problem that the existing photocuring technology cannot simultaneously have high precision and excellent conductive circuit printing. The low-solid-phase filling mixed silver photocuring printing conductive ink is prepared from a prepolymer, active monomers, a photoinitiator, a dispersing agent, silver powder and a silver precursor. The preparation method comprises the following steps: 1, weighing; 2, mixing and dissolving the weighed prepolymer, active monomers and silver precursor to form a uniform solution, then adding the dispersing agent and silver powder and uniformly mixing, and finally adding the photoinitiator and vacuum deaerating. The printing method comprises the following steps: 1, coating or spraying on a plane or curved surface substrate; 2, ultraviolet light path scanning curing; 3, light treatment or heat treatment. The application is used for the low-solid-phase filling mixed silver photocuring printing conductive ink and the preparation and printing thereof.

Description

Technical Field

[0001] This invention relates to photocurable conductive inks for printing, their preparation methods, and printing methods. Background Technology

[0002] With the development and transformation of additive manufacturing technology, its ability to achieve customized and complex structural design and manufacturing has shown great application potential in the field of electronic component manufacturing. Photopolymerization technology, an emerging method for forming circuits, offers higher printing precision compared to inkjet printing, direct writing, or screen printing. Furthermore, as a non-contact printing method, it can achieve complex molding on non-planar substrate surfaces. Therefore, this method can not only improve the performance and quality of electronic components but also enable multifunctionality and broaden their application range.

[0003] However, unlike ceramic materials, metal fillers and resin slurries typically have a large refractive index difference and a high extinction coefficient, and the solid content of the filler is a prerequisite for preparing circuits with high conductivity. Therefore, the use of photopolymerization technology to print high-precision circuits with excellent conductivity is greatly limited. Summary of the Invention

[0004] This invention aims to solve the problem that existing photopolymerization technology cannot simultaneously achieve high precision and excellent conductivity in circuit printing, and thus provides a low-solid-phase filled mixed silver photopolymerization conductive ink, its preparation method, and printing method.

[0005] A low-solid-phase filled mixed silver photocurable conductive ink for printing is prepared by mass fractions of 10 to 30 parts prepolymer, 20 to 30 parts active monomer, 0.5 to 4 parts photoinitiator, 1 to 5 parts dispersant, 20 to 30 parts silver powder and 5 to 20 parts silver precursor.

[0006] The photoinitiator is ethyl 2,4,6-trimethylbenzoylphenylphosphonate;

[0007] The silver powder is in the form of flakes with a particle size of 0.1 μm to 10 μm;

[0008] The silver precursor is silver trifluoroacetate.

[0009] A method for preparing a low-solid-phase filled mixed silver photocurable conductive ink for printing, comprising the following steps:

[0010] 1. Weigh out 10 to 30 parts of prepolymer, 20 to 30 parts of active monomer, 0.5 to 4 parts of photoinitiator, 1 to 5 parts of dispersant, 20 to 30 parts of silver powder, and 5 to 20 parts of silver precursor by weight.

[0011] 2. The weighed prepolymer, active monomer and silver precursor are mixed and dissolved to form a homogeneous solution. Then the dispersant and silver powder are added and mixed evenly. Finally, the photoinitiator is added and vacuum degassing is performed to obtain a low solid phase filled mixed silver photocurable conductive ink for printing.

[0012] A method for printing a low-solid-phase filled mixed silver photocurable conductive ink, comprising the following steps:

[0013] 1. Apply or spray low-solid-phase filled mixed silver photocurable conductive ink onto a flat or curved substrate;

[0014] 2. Circuit design using modeling software, under the conditions of ultraviolet light wavelength of 350nm~420nm, power of 5mW~10mW and scanning speed of 5mm / s~30mm / s, ultraviolet light path scanning and curing are performed according to the preset printing pattern;

[0015] 3. Clean the ink outside the pattern with isopropanol solution, and then perform light treatment or heat treatment to complete the printing method of low solid phase filled mixed silver photocurable conductive ink.

[0016] The beneficial effects of this invention are:

[0017] This invention combines a low-solid-content silver filler (20-30 parts silver powder) with a precursor silver that is soluble in photosensitive material systems. This not only reduces the amount of solid filler used, thus mitigating severe linewidth miscuring caused by light scattering effects, but also, because the selected precursor silver is soluble in photosensitive materials, the low-solid-content filler facilitates rapid curing under low-dose UV exposure, resulting in a conductive film with excellent mechanical strength and adhesion. Secondly, the precursor silver, after curing, can be reduced by light and heat to form nano-silver particles between the flake-like elemental silver particles. This allows for conductive pathways even with low-solid-content filler, eliminating the need for high-temperature sintering, which is beneficial for the application of conductive inks in more electronic component fields, while also providing high-precision and excellent conductive circuit printing. Furthermore, by adjusting the ratio of prepolymer to active monomer and using low-solid-content filler, this invention produces a photocurable conductive ink with a low viscosity (0.5 Pa·s to 1 Pa·s), which facilitates uniform coating thickness on planar or curved substrates through coating or spraying. Attached Figure Description

[0018] Figure 1 This is a SEM image of the conductive pattern printed on the substrate in step three of the printing method in Example 1.

[0019] Figure 2The images shown are SEM images of the conductive patterns before and after heat treatment in steps two and three of the printing method in Example 3. a is after heat treatment, and b is before heat treatment.

[0020] Figure 3 This is a physical image of the conductive pattern printed on the curved substrate in step three of the printing method in Example 5. Detailed Implementation

[0021] Specific Implementation Method 1: This implementation method is a low solid phase filled mixed silver photocurable conductive ink for printing, which is prepared by mass parts of 10 to 30 parts of prepolymer, 20 to 30 parts of active monomer, 0.5 to 4 parts of photoinitiator, 1 to 5 parts of dispersant, 20 to 30 parts of silver powder and 5 to 20 parts of silver precursor.

[0022] The photoinitiator is ethyl 2,4,6-trimethylbenzoylphenylphosphonate;

[0023] The silver powder is in the form of flakes with a particle size of 0.1 μm to 10 μm;

[0024] The silver precursor is silver trifluoroacetate.

[0025] The beneficial effects of this embodiment are:

[0026] This embodiment uses a combination of silver filler with a low solid content (20-30 parts silver powder) and a precursor silver that is soluble in the photosensitive material system. This not only reduces the amount of solid filler used, thus mitigating the severe linewidth miscuring caused by light scattering effects, but also, because the selected precursor silver is soluble in the photosensitive material, the low solid content allows for rapid curing under low-dose UV exposure, resulting in a conductive film layer with excellent mechanical strength and adhesion. Secondly, the precursor silver, after curing, can be reduced by light and heat to form nano-silver particles between the flake-like elemental silver particles. This allows for conductive pathways even with low solid content, eliminating the need for high-temperature sintering, which is beneficial for the application of conductive inks in more electronic component fields, while also providing high-precision and excellent conductive circuit printing. Furthermore, by adjusting the ratio of prepolymer to active monomer and using low solid content filling, this embodiment produces a photocurable conductive ink with a low viscosity (0.5 Pa·s to 1 Pa·s), which facilitates uniform coating thickness on planar or curved substrates through coating or spraying.

[0027] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the prepolymer is epoxy acrylate or polyurethane acrylate. Everything else is the same as in Specific Implementation Method One.

[0028] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the active monomer is isobornyl acrylate, 1,6-hexanediol diacrylate, or polyethylene glycol diacrylate. Everything else is the same as in Specific Implementation Method One or Two.

[0029] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the dispersant is BYK110 or polyethylene glycol 200. Everything else is the same as in Specific Implementation Methods One to Three.

[0030] Specific Implementation Method 5: This implementation method provides a method for preparing a low-solid-phase filled mixed silver photocurable conductive ink, which is carried out according to the following steps:

[0031] 1. Weigh out 10 to 30 parts of prepolymer, 20 to 30 parts of active monomer, 0.5 to 4 parts of photoinitiator, 1 to 5 parts of dispersant, 20 to 30 parts of silver powder, and 5 to 20 parts of silver precursor by weight.

[0032] 2. The weighed prepolymer, active monomer and silver precursor are mixed and dissolved to form a homogeneous solution. Then the dispersant and silver powder are added and mixed evenly. Finally, the photoinitiator is added and vacuum degassing is performed to obtain a low solid phase filled mixed silver photocurable conductive ink for printing.

[0033] Specific Implementation Method Six: This implementation method provides a printing method for a low-solid-phase filled mixed silver photocurable conductive ink, which is carried out according to the following steps:

[0034] 1. Apply or spray low-solid-phase filled mixed silver photocurable conductive ink onto a flat or curved substrate;

[0035] 2. Circuit design using modeling software, under the conditions of ultraviolet light wavelength of 350nm~420nm, power of 5mW~10mW and scanning speed of 5mm / s~30mm / s, ultraviolet light path scanning and curing are performed according to the preset printing pattern;

[0036] 3. Clean the ink outside the pattern with isopropanol solution, and then perform light treatment or heat treatment to complete the printing method of low solid phase filled mixed silver photocurable conductive ink.

[0037] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that the substrate mentioned in step one is a glass substrate, a ceramic substrate, or a plastic substrate. Everything else is the same as in Specific Implementation Method Six.

[0038] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Six or Seven in that: in step one, a low-solid-phase filled mixed silver photocurable conductive ink is coated or sprayed onto a flat or curved substrate with a coating thickness of 20μm to 100μm. Everything else is the same as in Specific Implementation Method Six or Seven.

[0039] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods Six to Eight in that the mass percentage of the isopropanol solution mentioned in step three is 30% to 60%. Everything else is the same as in Specific Implementation Methods Six to Eight.

[0040] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods Six to Nine in that the light treatment described in step three is specifically performed at a wavelength of 350nm to 420nm and a power density of 20mW / cm². 2 ~80mW / cm 2 Under the specified conditions, the light treatment lasts for 10 to 30 minutes; the heat treatment described in step three is specifically performed at a temperature of 100°C to 200°C for 30 to 60 minutes. Other aspects are the same as in specific embodiments six to nine.

[0041] The beneficial effects of the present invention are verified using the following embodiments:

[0042] Example 1:

[0043] A low-solid-phase filled mixed silver photocurable conductive ink for printing is prepared by mass fractions of 22 parts prepolymer, 24 parts active monomer, 2 parts photoinitiator, 2 parts dispersant, 20 parts silver powder and 20 parts silver precursor.

[0044] The photoinitiator is ethyl 2,4,6-trimethylbenzoylphenylphosphonate;

[0045] The silver powder is in the form of flakes with an average particle size of 1 μm;

[0046] The silver precursor is silver trifluoroacetate.

[0047] The prepolymer is polyurethane acrylate.

[0048] The active monomer is polyethylene glycol diacrylate.

[0049] The dispersant is BYK110.

[0050] The preparation method of the above-mentioned low-solid-phase filled mixed silver photocurable conductive ink is carried out according to the following steps:

[0051] 1. Weigh out 22 parts of prepolymer, 24 parts of reactive monomer, 2 parts of photoinitiator, 2 parts of dispersant, 20 parts of silver powder, and 20 parts of silver precursor by weight.

[0052] 2. The weighed prepolymer, active monomer and silver precursor are mixed and dissolved to form a homogeneous solution. Then the dispersant and silver powder are added and mixed evenly. Finally, the photoinitiator is added and vacuum degassing is performed to obtain a low solid phase filled mixed silver photocurable conductive ink for printing.

[0053] The above-mentioned printing method for a low-solid-phase filled mixed silver photocurable conductive ink is carried out according to the following steps:

[0054] 1. Under the condition of a coating speed of 10 mm / s and a coating thickness of 20 μm, a photocurable conductive ink with low solid phase filled mixed silver is applied to a planar substrate.

[0055] 2. Circuit design using modeling software, under the conditions of ultraviolet light wavelength of 405nm, power of 10mW and scanning speed of 20mm / s, ultraviolet light path scanning and curing are performed according to the preset printing pattern.

[0056] 3. Clean the ink outside the pattern with a 50% isopropanol solution, then perform a cleaning process at a wavelength of 405nm and a power density of 40mW / cm². 2 Under these conditions, the substrate was treated with light for 10 minutes to obtain the conductive pattern printed on the substrate.

[0057] The substrate mentioned in step one is an alumina ceramic substrate.

[0058] Example 2: This example differs from Example 1 in the following ways: Printing method: In step two, the scanning speed is 10 mm / s; in step three, the light treatment is replaced with heat treatment, specifically heat treatment at 120°C for 30 minutes. Everything else is the same as in Example 1.

[0059] Example 3: This example differs from Example 1 in the following ways: Printing method: In step one, the coating thickness is 40 μm; in step two, the scanning speed is 10 mm / s; in step three, the light treatment is replaced with heat treatment, specifically heat treatment at 120°C for 30 minutes. Everything else is the same as in Example 1.

[0060] Example 4: This example differs from Example 1 in that it is a low-solid-phase filled mixed silver photocurable conductive ink for printing, which is prepared by mass fractions of 24 parts prepolymer, 30 parts active monomer, 3 parts photoinitiator, 3 parts dispersant, 30 parts silver powder and 10 parts silver precursor.

[0061] The silver powder is in flake form with an average particle size of 0.5 μm;

[0062] The active monomer is 1,6-hexanediol diacrylate;

[0063] Printing method: In step two, the power is 20mW; in step three, the light treatment is replaced with heat treatment, specifically heat treatment at 120℃ for 60 minutes. Everything else is the same as in Example 1.

[0064] Example 5: This example differs from Example 1 in that the planar substrate is replaced with a curved substrate in step one; the substrate is an acrylic plastic substrate with a radius of curvature of 2.5 cm. Everything else is the same as in Example 1.

[0065] Comparative Experiment 1: The difference between this embodiment and Embodiment 1 is that the printing method is: the lighting process in step three is omitted. Everything else is the same as Embodiment 1.

[0066] Comparative Experiment 2: This example differs from Example 3 in that the silver precursor is omitted from the low-solid-phase filled mixed silver photocurable conductive ink, and the silver powder content is 29.8 parts; the heat treatment in step 3 is also omitted. Everything else is the same as in Example 3.

[0067] Calculations show that m(C2F2O2Ag) / m(Ag) = 221 / 108. Theoretically, 20 parts of silver trifluoroacetate can be reduced to 9.8 parts of elemental silver. Therefore, the silver content is the same in Comparative Experiment 2 and Example 3.

[0068] Test method:

[0069] 1. Viscosity test: The low solid phase filled mixed silver photocurable conductive ink was tested at room temperature using the HAAKE rheometer parallel plate method with a plate diameter of 30 mm and a plate gap of 0.45 mm.

[0070] 2. Polymerization Rate: The modulus change of the low-solid-phase filled silver-mixed photocurable conductive ink was measured in real time under continuous ultraviolet light irradiation. The polymerization rate was evaluated by the maximum value of the derivative of the modulus with respect to time. The wavelength of the ultraviolet curing unit was 405 nm, and the irradiation intensity was 1% of the peak radiation intensity, which was 10300 mW / cm². 2 .

[0071] 3. Line width resolution test: The conductive pattern printed on the substrate is measured using a high-definition optical microscope.

[0072] 4. Morphology test of the sample after photothermal treatment: The conductive pattern printed on the substrate was observed using a scanning electron microscope.

[0073] 5. Resistance: Connect the two ends of the conductive pattern printed on the substrate to the red and black probes of a multimeter to test its resistance value.

[0074] 6. Conductivity: Print six 1cm×1cm square conductive films according to the method in the example, test them with a four-probe resistance meter, and take the average value.

[0075] 7. Pencil Hardness: Using pencils of different hardness, lines are drawn on the surface of the conductive pattern printed on the substrate, and the abrasion resistance is evaluated by observing the scratches.

[0076] The test results are shown in Table 1:

[0077] Table 1

[0078]

[0079] In the table, “——” represents the establishment of a non-conductive path, i.e., a non-conductive state; the specific meaning of the incorrect curing width in the table is the difference between the actual curing test line width value and the designed line width, which is designed to be 40μm.

[0080] As shown in Table 1, the low-solid-phase filled mixed silver photocurable conductive ink not only exhibits high polymerization rate and printing linewidth accuracy, but also excellent electrical conductivity and pencil hardness, enabling the printing and molding of precise conductive layers on planar or curved substrates. Comparison of Examples 1 and 2 with Comparative Experiment 1 demonstrates that this photocurable conductive ink can establish a conductive network after light irradiation or low-temperature heat treatment, giving the conductive film excellent electrical properties. This is applicable to the circuit fabrication and connection of various high-precision electronic components. Comparison of Example 3 with Comparative Experiment 2 shows that using micron- or submicron-sized flake silver powder and silver trifluoroacetate as a mixed silver source, nano-silver can be generated between the flake silver particles after low-temperature heat treatment, thus creating an effective conductive path and achieving excellent electrical properties. Pure flake silver particles, however, cannot achieve interparticle bonding and are therefore non-conductive. Furthermore, comparison of Example 3 and Comparative Experiment 2 shows that the filling of more flake silver particles reduces the polymerization rate of the conductive ink and the pencil hardness of the conductive film.

[0081] Figure 1 This is a SEM image of the conductive pattern printed on the substrate in step three of the printing method in Example 1. As shown in the image, after light irradiation, silver trifluoroacetate has been reduced to silver nanoparticles, which fill the spaces between the sheet-like silver particles. This allows the sheet-like particles to establish conductive paths through the silver nanoparticles, greatly reducing the tunneling resistance.

[0082] Figure 2 The images show SEM images of the conductive patterns before and after heat treatment in steps two and three of the printing method in Example 3. Image a shows the pattern after heat treatment, and image b shows the pattern before heat treatment. As can be seen from the images, after heat treatment, silver trifluoroacetate is thermally reduced to silver nanoparticles, filling the spaces between the micron-sized silver flakes. However, the conductive pattern layer without heat treatment does not produce silver nanoparticles; the spaces between the flake-shaped silver particles are completely filled by polymer, hindering the formation of conductive paths.

[0083] Figure 3This is a photograph of the conductive pattern printed on the curved substrate in step three of the printing method in Example 5. As shown in the figure, the low-solid-phase filled mixed silver photocurable conductive ink of Example 5 can achieve good printing on the curved substrate under ultraviolet light scanning. After cleaning, the conductive pattern structure is clear and maintains good adhesion to the substrate without peeling off.

Claims

1. A low solid packed silver hybrid photocurable printing conductive ink, characterized by It is prepared by 22-24 parts of prepolymers, 20-30 parts of active monomers, 2-3 parts of photoinitiators, 2-3 parts of dispersants, 20-30 parts of silver powder and 5-20 parts of silver precursor by mass fraction; The prepolymers are epoxy acrylate or polyurethane acrylate; The active monomers are isobornyl acrylate, 1,6-hexanediol diacrylate or polyethylene glycol diacrylate; The photoinitiator is 2,4,6-trimethylbenzoyl phenyl ethyl phosphonate; The silver powder is flaky silver powder with a particle size of 0.1-1 μm; The silver precursor is silver trifluoroacetate; The printing method of the above low solid phase filling mixed silver photocuring printing conductive ink is as follows: I. The low solid phase filling mixed silver photocuring printing conductive ink is coated or sprayed on a flat or curved substrate; II. Circuit design is performed using modeling software, and the printing pattern is scanned and cured under the conditions of ultraviolet wavelength of 350-420 nm, power of 5-10 mW and scanning speed of 5-30 mm / s; III. The ink outside the pattern is cleaned with isopropanol solution, and then light treatment or heat treatment is performed, thereby completing the printing method of the low solid phase filling mixed silver photocuring printing conductive ink; The light treatment is specifically under the condition of wavelength of 350nm-420nm and power density of 20mW / cm 2 80mW / cm 2 for 10-30min; and the heat treatment is specifically under the condition of temperature of 100-200℃ for 30-60min.

2. The low solid content silver hybrid light-cured printing conductive ink according to claim 1, wherein The dispersant is BYK110 or polyethylene glycol 200.

3. The low solid content silver hybrid light-cured printing conductive ink according to claim 1, wherein The substrate in step I is a glass substrate, a ceramic substrate or a plastic substrate.

4. The low solid content silver hybrid light-cured printing conductive ink according to claim 1, wherein In step I, the low solid phase filling mixed silver photocuring printing conductive ink is coated or sprayed on a flat or curved substrate with a coating thickness of 20-100 μm.

5. The low solid content silver hybrid printed conductive ink according to claim 1, wherein The mass percentage of the isopropanol solution in step III is 30-60%.

6. The method for preparing a low-solid-phase filled mixed silver photocurable conductive ink for printing as described in claim 1, characterized in that... It is performed as follows: I. 22-24 parts of prepolymers, 20-30 parts of active monomers, 2-3 parts of photoinitiators, 2-3 parts of dispersants, 20-30 parts of silver powder and 5-20 parts of silver precursor are weighed by mass fraction; II. The weighed prepolymers, active monomers and silver precursor are mixed and dissolved to form a uniform solution, then the dispersant and silver powder are added and mixed uniformly, and finally the photoinitiator is added and vacuum degassed to obtain the low solid phase filling mixed silver photocuring printing conductive ink.

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