Nickel-based conductive paste for aerosol jet printing, preparation method and application

Abstract

The present invention discloses a nickel-based conductive paste, a preparation method and an application for aerosol jet printing, wherein the nickel-based conductive paste comprises the following components by mass percentage: nano nickel or nickel-based alloy powder: 0.5-10wt%, small molecule dispersant: 60-95wt%, surfactant: 0.5-12wt%. The method comprises: weighing a set proportion of dispersant and surfactant for mixing and dispersing, and slowly adding a set proportion of nano nickel powder or nickel-based alloy during stirring and continuously dispersing for a certain time to obtain a primary slurry; the primary slurry is allowed to stand for half an hour, and 95% of the volume of the primary slurry is sucked from top to bottom with a pipette to obtain a nickel-based conductive paste; wherein the stirring mode is ultrasonic dispersion or mechanical stirring, the mechanical stirring rate is 100-400rpm, and the stirring time is 10-60min; the ultrasonic dispersion power is 30-200W, and the ultrasonic time is 3-30min. The present invention solves the problem that nickel-based conductive paste in the prior art is difficult to be used in aerosol jet printing.

Description

Technical Field

[0001] The present invention relates to the technical field of conductive materials, and in particular to a nickel-based conductive paste for aerosol jet printing, a preparation method and an application thereof. Background Art

[0002] Metallic nickel is a good electromagnetic shielding material. Nickel-based coatings are widely used in industrial electromagnetic shielding, especially in the medical and military fields, and can meet the needs of most customers. Therefore, it is very important to develop nickel-based electromagnetic shielding films and corresponding preparation technologies.

[0003] Aerosol jet printing technology, as a non-contact, fast, low-cost, and environmentally friendly micro-scale additive manufacturing technology, has aroused great interest. Compared with inkjet printing technology, aerosol jet printing technology has a series of advantages such as high material compatibility, nozzles are not easy to clog, and the printing substrate form is not limited (flat or curved). It can realize the deposition of atomized droplets in specific areas through numerical control. Therefore, this technology can realize the printing and preparation of nickel-based thin films on non-planar device surfaces.

[0004] One of the key conditions for aerosol jet printing of nickel-based electromagnetic shielding conductive films is the preparation of nickel-based slurry. This technology requires that nano nickel-based powders can be stably dispersed in the slurry, and that the nickel-based slurry can be evenly atomized into micro droplets by ultrasound or pneumatics and then stably transported to the print head by the carrier gas flow.

[0005] Nickel-based nanopowders are prone to agglomeration due to their magnetic properties, so conventional nickel-based slurries contain a large amount of polymer resin as a stabilizer, which increases the viscosity of the slurry, making it difficult to atomize and transport it through airflow, and easily clogs the nozzle, making it difficult to use in aerosol jet printing. In addition, conventional slurries need to be subjected to high temperature or laser sintering to remove insulating materials after traditional spraying or screen printing in order to make the nickel-based film have a low resistance, which limits its use conditions. Summary of the invention

[0006] In view of this, an object of the present invention is to provide a nickel-based conductive paste for aerosol jet printing, a preparation method and an application thereof, aiming to solve at least one problem raised in the background technology.

[0007] The embodiment of the present invention is implemented as follows:

[0008] A nickel-based conductive paste comprises the following components by mass percentage:

[0009] Nano nickel or nickel-based alloy powder: 0.5-10wt%, small molecule dispersant: 60-95wt%, surfactant: 0.5-12wt%.

[0010] Furthermore, in the above-mentioned nickel-based conductive paste, the nickel-based powder mainly includes one or more of nano nickel, nickel-copper, nickel-silver, and nickel-iron alloy.

[0011] Furthermore, in the above nickel-based conductive paste, the size of the nickel-based powder is 5-500nm.

[0012] Furthermore, in the above nickel-based conductive slurry, the small molecule dispersant is a compound of water, ethanol, ethylene glycol, isopropanol, kerosene, terpineol, dihydroterpineol, tetrahydrofuran, and ethyl acetate.

[0013] Furthermore, in the above nickel-based conductive paste, the surfactant is a compound of oleic acid, 2H, 2H-perfluorooctanoic acid, oleylamine, diethanolamine oleate, citric acid, oxalic acid, disodium ethylenediaminetetraacetate, sodium pyrophosphate, and lauryl alcohol polyoxyethylene ether.

[0014] Another object of the present invention is to provide a method for preparing a nickel-based conductive paste, which is used to prepare the nickel-based conductive paste according to any one of the above claims, and the method comprises:

[0015] Weigh a set proportion of dispersant and surfactant, mix and disperse them, and slowly add a set proportion of nano nickel powder or nickel-based alloy during the dispersion process and continue to disperse for a certain period of time to obtain a primary slurry;

[0016] The primary slurry is allowed to stand for half an hour, and 95% of the volume of the primary slurry is sucked from top to bottom with a pipette to obtain a nickel-based conductive slurry;

[0017] The dispersion method is ultrasonic dispersion or mechanical stirring, the mechanical stirring rate is 100-400 rpm, and the stirring time is 10-60 min; the ultrasonic dispersion power is 30-200 W, and the ultrasonic time is 3-30 min.

[0018] Another object of the present invention is to provide an application method of the nickel-based conductive paste prepared by the above-mentioned preparation method, the application method comprising:

[0019] Draw the conductive film pattern to be printed using CAD software, and import the conductive film pattern into the aerosol jet printer operating software for identification;

[0020] The nickel-based conductive paste is printed in a pneumatic or ultrasonic atomization mode by using an aerosol jet printing method, and a stable transport gas is obtained by adjusting the atomization airflow and the virtual impactor negative pressure airflow;

[0021] The corresponding print head is selected, and the nickel-based conductive film is finally obtained with the preset bound airflow, workbench temperature, printing speed and number of printing cycles.

[0022] Furthermore, in the above application method, the atomization method selected is pneumatic or ultrasonic atomization. When the size of nickel-based particles is 5-15nm, ultrasonic atomization is selected, the atomization frequency is 1.7 MHz, the carrier gas flow rate is 3-10Sccm, and the bound gas flow rate is 120-180Sccm; when the size of nickel-based particles is 16-500nm, pneumatic atomization is selected, the atomization gas flow rate is 0.5-2NL / min, the virtual impactor negative pressure gas flow rate is -1.5-(-3)Pa, and the bound gas flow rate is 50-300Sccm.

[0023] Furthermore, in the above application method, the printing nozzle diameter is 300-1000 μm, the workbench temperature is 20-120° C., the printing speed is 5-30 mm / s, the height of the printing nozzle from the printing bottom is 5-20 mm, and the number of repeated printings is 1-10.

[0024] Furthermore, in the above application method, the resistivity of the conductive film is less than 4Ωcm -2 , the electromagnetic shielding effect reaches 45.5dB.

[0025] Compared with the prior art, the nickel-based conductive slurry proposed in the present invention not only promotes the dispersion of nickel-based powders but also effectively inhibits their oxidation by adding surfactants. By adjusting the type and proportion of addition to control the boiling point and surface tension of the droplets, the Marangoni flow inside the droplets can be enhanced, and the coffee ring effect produced during the drying process of the droplets can be effectively inhibited, thereby improving the dispersion effect of the nickel-based powder in the slurry, so that it can be evenly atomized into micro-droplets by ultrasound or pneumatics and then stably transported to the printing nozzle by the carrier gas flow, thereby solving the problem in the prior art that the increased viscosity of the slurry is not conducive to its atomization and airflow transmission, and it is easy to clog the nozzle, so it is difficult to be suitable for aerosol jet printing.

[0026] In addition, the present invention can also have at least the following beneficial effects:

[0027] 1. The above nickel-based conductive slurry can be used for aerosol jet printing of nickel-based electromagnetic shielding films, which can effectively solve the problems of high viscosity, poor atomization effect, and large proportion of non-conductive fillers in traditional metal slurries. Aerosol jet printing technology can be used to achieve high-performance nickel-based film printing and preparation on non-planar structure surfaces.

[0028] 2. The addition of citric acid, stearic acid, sodium pyrophosphate, etc. as surfactants not only promotes the dispersion of nickel-based powders, but also effectively inhibits its oxidation.

[0029] 3. The addition of diethanolamine oleate can anchor the acidic sites on the surface of nickel-based particles, making up for the defect of only using weakly acidic surfactants to anchor the alkaline sites on the surface in the traditional method, and synergistically improving the dispersion effect of nickel-based powder in the slurry.

[0030] 4. Small molecule, low viscosity, low boiling point dispersants or additives are conducive to the formation of atomized droplets (especially for ultrasonic atomization) and the rapid drying of atomized droplets on the surface of the printed substrate.

[0031] 5. There is no need to add high-boiling-point polymer resin binder to the slurry, and low-resistance nickel-based film can be obtained without high-temperature sintering.

[0032] 6. By adjusting the addition type and proportion to control the boiling point and surface tension of the droplets, the Marangoni flow inside the droplets can be enhanced, the coffee ring effect produced during the droplet drying process can be effectively suppressed, and the final nickel-based film can be more uniform and dense. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram showing the conductive film printed by the nickel-based conductive paste prepared in Example 2 of the present invention under a microscope;

[0034] Figure 2 This is a schematic diagram showing the conductive film printed by the nickel-based conductive paste prepared in Example 6 of the present invention under a microscope;

[0035] Figure 3 This is a schematic diagram showing the conductive film printed out of the nickel-based conductive paste prepared in Comparative Examples 1 and 2 of the present invention under a microscope.

[0036] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0037] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Several embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0038] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0040] Aerosol jet printing technology, as a non-contact, fast, low-cost, and environmentally friendly micro-scale additive manufacturing technology, has aroused great interest. Compared with inkjet printing technology, aerosol jet printing technology has a series of advantages such as high material compatibility, nozzles are not easy to clog, and the printing substrate form is not limited (flat or curved). It can realize the deposition of atomized droplets in specific areas through numerical control. Therefore, this technology can realize the printing preparation of nickel-based conductive films on non-planar device surfaces.

[0041] One of the key conditions for aerosol jet printing of nickel-based electromagnetic shielding conductive films is the preparation of nickel-based slurry. This technology requires that nano nickel-based powders can be stably dispersed in the slurry, and that the nickel-based slurry can be evenly atomized into micro droplets by ultrasound or pneumatics and then stably transported to the print head by the carrier gas flow.

[0042] In the prior art, nickel-based slurry contains a large amount of polymer resin as a stabilizer, which increases the viscosity of the slurry and is not conducive to its atomization and air flow transmission, and is easy to clog the nozzle, so it is difficult to be applied to aerosol jet printing.

[0043] Therefore, the present invention proposes a nickel-based conductive paste for aerosol jet printing, a preparation method and an application thereof to solve the problem in the prior art that conductive paste is difficult to apply to aerosol jet printing.

[0044] Wherein, the nickel-based conductive paste comprises the following components by mass percentage:

[0045] Nano nickel or nickel-based alloy powder: 0.5-10wt%, small molecule dispersant: 60-95wt%, surfactant: 0.5-12wt%.

[0046] Specifically, the nickel-based powder mainly includes one or more of nano nickel, nickel copper, nickel silver, and nickel iron alloy, and the size of the nickel-based powder is 5-500nm. The small molecule dispersant is a compound of water, ethanol, ethylene glycol, isopropanol, kerosene, terpineol, dihydroterpineol, tetrahydrofuran, and ethyl acetate, so that it accounts for 60-95wt% of the entire slurry, preferably 75-90wt%. The preferred solvent and the ratio are ethanol (7-9): ethylene glycol (0.2-1): tetrahydrofuran (0.1-0.5). The surfactant is a compound of oleic acid, 2H, 2H-perfluorooctanoic acid, oleylamine, diethanolamine oleate, citric acid, oxalic acid, disodium ethylenediaminetetraacetate, sodium pyrophosphate, and lauryl alcohol polyoxyethylene ether. The preferred surfactant and the ratio are citric acid (0.5-1.5): diethanolamine oleate (1): nafion (0.2); the total addition amount is 0.5-12wt% of the slurry, preferably 2-5wt%.

[0047] On the other hand, the present invention also provides a method for preparing a nickel-based conductive paste, which is used to prepare the above-mentioned nickel-based conductive paste, and the method comprises:

[0048] Weigh a dispersant and a surfactant in a set ratio, mix and stir, and slowly add a nano nickel powder or a nickel-based alloy in a set ratio during the stirring process and continue stirring for a certain period of time to obtain a primary slurry;

[0049] The primary slurry is allowed to stand for half an hour, and 95% of the volume of the primary slurry is sucked from top to bottom with a pipette to obtain a nickel-based conductive slurry;

[0050] The stirring method is ultrasonic stirring or mechanical stirring, the mechanical stirring rate is 100-400 rpm, and the stirring time is 10-60 min; the ultrasonic stirring power is 30-200 W, and the ultrasonic time is 3-30 min.

[0051] Preferably, the nickel-based powder is nickel or nickel-silver alloy, the particle size is 2-50 nm, the stirring rate is 100-250 rpm, the stirring time is 10-30 min, the ultrasonic power is 50-100 W, and the ultrasonic time is 4-15 min.

[0052] The present invention also provides an application method of the nickel-based conductive paste prepared by the above-mentioned preparation method, and the application method comprises:

[0053] Draw the conductive film pattern to be printed using CAD software, and import the conductive film pattern into the aerosol jet printer operating software for identification;

[0054] The aerosol jet printing method is selected to print the nickel-based conductive paste in a pneumatic atomization mode, and a stable transport gas is obtained by adjusting the atomization airflow and the virtual impactor negative pressure airflow;

[0055] The corresponding print head is selected, and the nickel-based conductive film is finally obtained with the preset bound airflow, workbench temperature, printing speed and number of printing cycles.

[0056] In the specific implementation, the pattern format can be .dxf, and the selected atomization method is pneumatic atomization or ultrasonic atomization. When the nickel-based particle size is 5-15nm, ultrasonic atomization is selected, the atomization frequency is 1.7 MHz, the carrier gas flow rate is 3-10Sccm, and the bound gas flow is 120-180Sccm. When the nickel-based particle size is 16-500nm, pneumatic atomization is selected, the atomization gas flow is 0.5-2NL / min, the virtual impactor negative pressure gas flow is -1.5-(-3)Pa, the bound gas flow is 50-300Sccm, the printing nozzle diameter is 300-1000μm, the workbench temperature is 20 to 120℃, the printing speed is 5-30mm / s, the height of the printing nozzle from the printing bottom is 5-20mm, and the number of repeated printing is 1-10.

[0057] Preferably, the amount of nickel-based conductive slurry added is 20-40 mL, the atomizing airflow is 1-1.5 NL / min, the virtual impactor negative pressure airflow is -2 - (-2.6) Pa, the printing nozzle diameter is 500-700 μm, the bound airflow is 100-200 Sccm, the workbench temperature is 60-120 ° C, the printing speed is 10-20 mm / s, the height of the printing nozzle from the printing bottom is 10-15 mm, and the number of repeated printings is 4-6.

[0058] In order to facilitate understanding of the present invention, the present invention will be described more fully below with reference to relevant embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0059] Example 1

[0060] 85 g of anhydrous ethanol, 10 g of dihydroterpineol, and 5 g of tetrahydrofuran were ultrasonically mixed to form a uniform mixed dispersant.

[0061] 4 g of citric acid, 3.1 g of diethanolamine oleate and 0.62 g of nafion solution were added to the mixed dispersant, and ultrasonic mixing was continued to obtain a uniform solution.

[0062] 3 g of nickel powder with an average particle size of 50 nm was weighed and added to the mixed solution, and the particles were dispersed by mechanical stirring of a polymer resin material. The stirring rate was 300 rpm and the stirring time was 40 min. After the stirring was completed, a primary nickel conductive slurry was obtained.

[0063] After the primary nickel conductive paste is left to stand for half an hour, 95% of the total volume is pipetted from top to bottom with a pipette to obtain the expected nickel-based conductive paste.

[0064] PET was selected as the substrate, and the obtained nickel-based conductive slurry was subjected to aerosol jet printing. The amount of nickel-based conductive slurry added was 30 mL, the atomizing airflow was 1 NL / min, the virtual impactor negative pressure airflow was -2 Pa, the printing nozzle diameter was 700 μm, the bound airflow was 100 Sccm, the workbench temperature was 80 ° C, the printing speed was 10 mm / s, the height of the printing nozzle from the printing bottom was 12 mm, the number of repeated printings was 4, and after the printing was completed, the nickel-based conductive film was taken out to obtain.

[0065] Example 2

[0066] 85 g of anhydrous ethanol, 10 g of dihydroterpineol, and 5 g of tetrahydrofuran were ultrasonically mixed to form a uniform mixed dispersant.

[0067] 4 g of citric acid, 3.1 g of diethanolamine oleate and 0.62 g of nafion solution were added to the mixed dispersant, and ultrasonic mixing was continued to obtain a uniform solution.

[0068] 3 g of nickel powder with an average particle size of 50 nm was weighed and added to the mixed solution, and ultrasonic dispersion was continued. The ultrasonic power was 50 W and the ultrasonic time was 10 min. After the ultrasonic dispersion was completed, a primary nickel conductive slurry was obtained.

[0069] After the primary nickel conductive paste is left to stand for half an hour, 95% of the total volume is pipetted from top to bottom with a pipette to obtain the expected nickel-based conductive paste.

[0070] PET was selected as the substrate, and the obtained nickel-based conductive slurry was subjected to aerosol jet printing. The amount of nickel-based conductive slurry added was 20 mL, the atomizing airflow was 1.5 NL / min, the virtual impactor negative pressure airflow was -2 Pa, the printing nozzle diameter was 600 μm, the bound airflow was 100 Sccm, the workbench temperature was 100 ° C, the printing speed was 10 mm / s, the height of the printing nozzle from the printing bottom was 10 mm, the number of repeated printings was 4, and after the printing was completed, the nickel-based conductive film was taken out to obtain.

[0071] Example 3

[0072] Weigh 90 g of anhydrous ethanol, 10 g of kerosene, and 5 g of tetrahydrofuran and mix them by ultrasonication to form a uniform mixed dispersant.

[0073] 5 g of sodium pyrophosphate, 3 g of lauryl alcohol polyoxyethylene ether and 0.62 g of nafion solution were added to the mixed dispersant, and ultrasonic mixing was continued to obtain a uniform solution.

[0074] 3.5 g of nickel powder with an average particle size of 20 nm was weighed and added to the mixed solution, and ultrasonic dispersion was continued. The ultrasonic power was 50 W and the ultrasonic time was 10 min. After the ultrasonic dispersion was completed, a primary nickel conductive slurry was obtained.

[0075] After the primary nickel conductive paste is left to stand for half an hour, 95% of the total volume is pipetted from top to bottom with a pipette to obtain the expected nickel-based conductive paste.

[0076] PET was selected as the substrate, and the obtained nickel-based conductive slurry was subjected to aerosol jet printing. The amount of nickel-based conductive slurry added was 20 mL, the atomizing airflow was 1.2 NL / min, the virtual impactor negative pressure airflow was -2.2 Pa, the printing nozzle diameter was 500 μm, the bound airflow was 200 Sccm, the workbench temperature was 60 ° C, the printing speed was 10 mm / s, the height of the printing nozzle from the printing bottom was 10 mm, the number of repeated printings was 4, and the printing was completed and the nickel-based conductive film was taken out to obtain.

[0077] Example 4

[0078] Weigh 90 g of anhydrous ethanol, 8 g of ethylene glycol, and 5 g of oleyl alcohol and mix them by ultrasonication to form a uniform mixed dispersant.

[0079] 4.5 g of oleic acid, 2.5 g of oleylamine and 0.5 g of nafion solution were added to the mixed dispersant, and ultrasonic mixing was continued to obtain a uniform solution.

[0080] Weigh 2 g of nickel-silver alloy powder with an average particle size of 100 nm and add it to the mixed solution, and continue to perform ultrasonic dispersion. The ultrasonic power is 100 W and the ultrasonic time is 12 min. After the ultrasonic dispersion is completed, a primary nickel conductive slurry is obtained.

[0081] After the primary nickel conductive paste is left to stand for half an hour, 95% of the total volume is pipetted from top to bottom with a pipette to obtain the expected nickel-based conductive paste.

[0082] Single crystal silicon was selected as the substrate, and the obtained nickel-based conductive slurry was subjected to aerosol jet printing. The amount of nickel-based conductive slurry added was 40 mL, the atomizing airflow was 1.5 NL / min, the virtual impactor negative pressure airflow was -2.2 Pa, the printing nozzle diameter was 700 μm, the bound airflow was 200 Sccm, the workbench temperature was 100 ° C, the printing speed was 20 mm / s, the height of the printing nozzle from the printing bottom was 12 mm, the number of repeated printings was 4, and the printing was completed and the nickel-based conductive film was taken out to obtain.

[0083] Example 5

[0084] Weigh 90 g of anhydrous ethanol, 6 g of ethylene glycol, and 3 g of ethyl acetate and mix them by ultrasonication to form a uniform mixed dispersant.

[0085] 4.2 g of stearic acid, 2 g of lauryl alcohol polyoxyethylene ether and 0.5 g of nafion solution were added to the mixed dispersant, and ultrasonic mixing was continued to obtain a uniform solution.

[0086] Weigh 2 g of nickel-iron alloy powder with an average particle size of 200 nm and add it to the mixed solution, and continue to perform ultrasonic dispersion. The ultrasonic rate is 100 W and the ultrasonic time is 15 min. After the ultrasonic dispersion is completed, a primary nickel conductive slurry is obtained.

[0087] After the primary nickel conductive paste is left to stand for half an hour, 95% of the total volume is pipetted from top to bottom with a pipette to obtain the expected nickel-based conductive paste.

[0088] Single crystal silicon was selected as the substrate, and the obtained nickel-based conductive slurry was subjected to aerosol jet printing. The amount of nickel-based conductive slurry added was 30 mL, the atomizing airflow was 1.2 NL / min, the virtual impactor negative pressure airflow was -2 Pa, the printing nozzle diameter was 700 μm, the bound airflow was 100 Sccm, the workbench temperature was 100 ° C, the printing speed was 10 mm / s, the height of the printing nozzle from the printing bottom was 10 mm, the number of repeated printings was 4, and after the printing was completed, the nickel-based conductive film was taken out to obtain.

[0089] Example 6

[0090] Weigh 90 g of isopropanol, 10 g of ethylene glycol, and 1.5 g of terpineol and mix them by ultrasonication to form a uniform mixed dispersant.

[0091] 4.2 g of stearic acid, 2 g of diethanolamine oleate and 0.5 g of nafion solution were added to the mixed dispersant, and ultrasonic mixing was continued to obtain a uniform solution.

[0092] Weigh 1 g of nickel-iron alloy powder with an average particle size of 200 nm and add it to the mixed solution, and continue to perform ultrasonic dispersion. The ultrasonic rate is 100 W and the ultrasonic time is 15 min. After the ultrasonic dispersion is completed, a primary nickel conductive slurry is obtained.

[0093] After the primary nickel conductive paste is left to stand for half an hour, 95% of the total volume is pipetted from top to bottom with a pipette to obtain the expected nickel-based conductive paste.

[0094] PET was selected as the substrate, and the obtained nickel-based conductive paste was subjected to aerosol jet printing. The printing conditions were the same as those in Example 2. After repeating the printing 4 times, a uniform and dense conductive film was obtained.

[0095] Example 7

[0096] Weigh 90 g of anhydrous ethanol, 5 g of kerosene, and 5 g of tetrahydrofuran and mix them by ultrasonication to form a uniform mixed dispersant.

[0097] 5 g of sodium pyrophosphate and 0.5 g of nafion solution were added to the mixed dispersant, and ultrasonic mixing was continued to obtain a uniform solution.

[0098] 3.5 g of nickel powder with an average particle size of 10 nm was weighed and added to the mixed solution, and ultrasonic dispersion was continued. The ultrasonic power was 50 W and the ultrasonic time was 10 min. After the ultrasonic dispersion was completed, a primary nickel conductive slurry was obtained.

[0099] After the primary nickel conductive paste is left to stand for half an hour, 95% of the total volume is pipetted from top to bottom with a pipette to obtain the expected nickel-based conductive paste.

[0100] PET was selected as the substrate, and the obtained nickel-based conductive slurry was subjected to aerosol jet printing by ultrasonic atomization. The amount of nickel-based conductive slurry added was 5 mL, the ultrasonic atomization frequency was 1.7 MHz, the carrier gas flow rate was 5 Sccm, the bound gas flow rate was 150 Sccm, and the workbench temperature was 50°C. The printing speed was 10 mm / s, the height of the printing nozzle from the bottom of the printing was 5 mm, the number of repeated printings was 6, and the nickel-based conductive film was obtained after the printing was completed and taken out.

[0101] In order to compare with the above-mentioned embodiments of the present invention, the present invention also provides the following comparative examples.

[0102] Comparative Example 1

[0103] 3 g of nickel powder with an average particle size of 50 nm was weighed and added to 100 g of anhydrous ethanol for ultrasonic dispersion. The ultrasonic power was 50 W and the ultrasonic time was 10 min. After the ultrasonic dispersion was completed, a primary nickel conductive slurry was obtained.

[0104] After the primary nickel conductive paste is left to stand for half an hour, 95% of the total volume is pipetted from top to bottom with a pipette to obtain the expected nickel-based conductive paste.

[0105] PET was selected as the substrate, and the obtained nickel-based conductive paste was subjected to aerosol jet printing. The printing conditions were the same as those in Example 2. After repeated printing for 4 times, no uniform and dense film could be obtained ( Figure 3 a) and is not conductive.

[0106] Comparative Example 2

[0107] 95 g of anhydrous ethanol and 5 g of oleic acid were ultrasonically mixed to form a uniform mixed solution.

[0108] 3 g of nickel powder with an average particle size of 50 nm was weighed and added to the above mixed solution for ultrasonic dispersion. The ultrasonic power was 50 W and the ultrasonic time was 10 min. After the ultrasonic dispersion was completed, a primary nickel conductive slurry was obtained.

[0109] After the primary nickel conductive paste is left to stand for half an hour, 95% of the total volume is pipetted from top to bottom with a pipette to obtain the expected nickel-based conductive paste.

[0110] PET was selected as the substrate, and the obtained nickel-based conductive paste was subjected to aerosol jet printing. The printing conditions were the same as those in Example 2. After 4 reprints, the solvent that had not evaporated in time still existed on the surface of the sample, and a uniform nickel-based film could not be formed ( Figure 3 b) and is not conductive.

[0111] Comparative Example 3

[0112] A certain brand of nickel conductive paste with a polymer resin binder was selected, and PET was used as the substrate for aerosol jet printing. Except for the maximum diameter (1000 μm) of the printing nozzle, the other printing conditions were the same as those in Example 2. First, the paste could not be uniformly atomized into micro droplets. Second, during the printing process, the materialized droplets were very easy to clog the print nozzle, resulting in the inability to form a uniform nickel-based film.

[0113] The nickel-based electromagnetic shielding films prepared from the nickel-based conductive pastes obtained in Examples 2 and 6 and Comparative Examples 1 and 2 by means of aerosol jet printing technology were respectively subjected to microscopic observation.

[0114] Combination Figures 1 to 3 It can be clearly seen that the conductive films printed in Example 2 and Example 6 are uniform and dense. Comparative Examples 1 and 2 cannot obtain uniform and dense films and are not conductive.

[0115] It can be clearly seen from the above embodiments and comparative examples that:

[0116] The addition of citric acid, stearic acid, sodium pyrophosphate and the like as surfactants not only promotes the dispersion of nickel-based powders, but also effectively inhibits its oxidation. The addition of diethanolamine oleate can anchor the acidic sites on the surface of nickel-based particles, making up for the defect of only using weakly acidic surfactants to anchor the alkaline sites on the surface in the traditional method, and synergistically improves the dispersion effect of nickel-based powders in the slurry. Small molecule, low viscosity, low boiling point dispersants or additives are conducive to the formation of atomized droplets (especially for ultrasonic atomization) and the rapid drying of atomized droplets on the printed substrate surface. No high boiling point polymer resin binder is required in the slurry, and a low resistance nickel-based film can be obtained without high temperature sintering. By adjusting the addition type and proportion to control the boiling point and surface tension of the droplets, the Marangoni flow inside the droplets can be enhanced, the coffee ring effect generated during the drying process of the droplets can be effectively inhibited, and the final nickel-based film can be more uniform and dense. However, the conductive slurry formed by adding oleic acid or polymer resin binders for the dispersion of traditional nickel nanoparticles is not suitable for aerosol jet printing technology.

[0117] 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.

[0118] The nickel-based slurry described above is mainly used for printing and preparing electromagnetic shielding films, but is also suitable for aerosol jet printing and preparing other nickel-based electronic information electronic devices.

[0119] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for applying a nickel-based conductive paste, characterized in that: The nickel-based conductive paste is printed by aerosol jet to obtain a dense conductive film, and the application method includes: Draw the conductive film pattern to be printed using CAD software, and import the conductive film pattern into the aerosol jet printer operating software for identification; The aerosol jet printing method is selected to print the nickel-based conductive paste in a pneumatic or ultrasonic atomization mode, and a stable transport gas is obtained by adjusting the atomization airflow and the virtual impactor negative pressure airflow; Select the corresponding print head, and finally obtain the nickel-based conductive film with the preset bound airflow, workbench temperature, printing speed and number of printing cycles; Wherein, the nickel-based conductive paste comprises the following components by mass percentage: Nano nickel or nickel-based alloy powder: 0.5-10wt%, small molecule dispersant: 60-95wt%, surfactant: 0.5-12wt%; Wherein, the small molecule dispersant is a compound of ethanol, ethylene glycol, isopropanol, kerosene, terpineol, dihydroterpineol, tetrahydrofuran, and ethyl acetate; The surfactant is a compound of diethanolamine oleate, citric acid and nafion solution, and the ratio of diethanolamine oleate, citric acid and nafion solution is 1:0.5-1.5:0.2; The size of nano nickel or nickel-based alloy powder is 5-500nm.

2. The application method according to claim 1, characterized in that: The selected atomization method is pneumatic or ultrasonic atomization. When the nickel-based particle size is 5-15nm, ultrasonic atomization is selected, the atomization frequency is 1.7 MHz, the carrier gas flow rate is 3-10Sccm, and the bound gas flow is 120-180Sccm; when the nickel-based particle size is 16-500nm, pneumatic atomization is selected, the atomization gas flow is 0.5-2NL / min, the virtual impactor negative pressure gas flow is -1.5-(-3)Pa, and the bound gas flow is 50-300Sccm.

3. The application method according to claim 1, characterized in that: The diameter of the printing nozzle is 300-1000 μm, the temperature of the workbench is 20-120° C., the printing speed is 5-30 mm / s, the height of the printing nozzle from the printing bottom is 5-20 mm, and the number of repeated printings is 1-10.

4. The application method according to claim 1, characterized in that: The resistivity of the conductive film is less than 4Ωcm -2 , the electromagnetic shielding effect reaches 45.5dB.

5. The application method according to claim 1, characterized in that: The preparation method of the nickel-based conductive paste comprises: Weigh a set proportion of dispersant and surfactant, mix and disperse them, and slowly add a set proportion of nano nickel powder or nickel-based alloy during the dispersion process and continue to disperse for a certain period of time to obtain a primary slurry; The primary slurry is allowed to stand for half an hour, and 95% of the volume of the primary slurry is sucked from top to bottom with a pipette to obtain a nickel-based conductive slurry; The dispersion method is ultrasonic dispersion or mechanical stirring, the mechanical stirring rate is 100-400 rpm, and the stirring time is 10-60 min; the ultrasonic dispersion power is 30-200 W, and the ultrasonic time is 3-30 min.

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