CN114724772A - Preparation method and application of conductive silver carbon paste - Google Patents

Preparation method and application of conductive silver carbon paste Download PDF

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Publication number
CN114724772A
CN114724772A CN202210447063.6A CN202210447063A CN114724772A CN 114724772 A CN114724772 A CN 114724772A CN 202210447063 A CN202210447063 A CN 202210447063A CN 114724772 A CN114724772 A CN 114724772A
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silver
conductive
carbon
black
conductive silver
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郭文杰
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South China University of Technology SCUT
Guangzhou Institute of Modern Industrial Technology
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South China University of Technology SCUT
Guangzhou Institute of Modern Industrial Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
    • H01B1/20—Conductive material dispersed in non-conductive organic material
    • H01B1/24—Conductive material dispersed in non-conductive organic material the conductive material comprising carbon-silicon compounds, carbon or silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B13/00—Apparatus or processes specially adapted for manufacturing conductors or cables
    • H01B13/0016—Apparatus or processes specially adapted for manufacturing conductors or cables for heat treatment
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/0011—Working of insulating substrates or insulating layers
    • H05K3/0055—After-treatment, e.g. cleaning or desmearing of holes
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
    • H05K3/42—Plated through-holes or plated via connections
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
    • H05K3/42—Plated through-holes or plated via connections
    • H05K3/423—Plated through-holes or plated via connections characterised by electroplating method
    • H05K3/424—Plated through-holes or plated via connections characterised by electroplating method by direct electroplating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention relates to the technical field of printed circuit board processing, and discloses a preparation method and application of conductive silver carbon paste. The preparation method comprises the steps of soaking nanoscale conductive carbon black in nitric acid and hydrogen peroxide, dispersing the nanoscale conductive carbon black in ethylene glycol, adding a silver nitrate solution and polyvinylpyrrolidone, mixing, adjusting the pH value of the mixture to be alkalescent, transferring the mixture into a hydrothermal reaction kettle for reaction, cooling, filtering, washing, drying, putting the mixture into an atmosphere furnace for calcination to obtain silver-loaded nano carbon black, and finally grinding and mixing the silver-loaded nano carbon black, a surfactant and pure water to obtain conductive silver carbon slurry. The conductive silver carbon paste has the beneficial effects that the conductive silver carbon paste provides a conductive silver carbon layer superior to a conductive carbon layer formed by carbon black or graphite for the metallization of the hole wall of the glass fiber layer of the printed circuit board, the black hole manufacturing process is simplified, and the production efficiency is improved.

Description

Preparation method and application of conductive silver carbon paste
Technical Field
The invention relates to the technical field of printed circuit board processing, in particular to a preparation method and application of conductive silver carbon paste prepared by metallization of holes of a printed circuit board.
Background
In the manufacturing process of printed circuit boards (PCB, FPC), conduction of interlayer conductors is achieved by drilling and then hole metallization techniques. The traditional technology is to adopt a chemical copper deposition (PTH) method to complete the hole metallization technology, but PTH solution contains various chemical substances which are harmful to ecological environment, such as EDTA, NTA, EDTP and formaldehyde which is easy to cause cancer, the wastewater treatment is complex and the cost is high; in addition, the stability of the PTH solution is poor, and the analysis and maintenance of the solution are complex; meanwhile, the PTH copper plating layer has poor mechanical properties and a complicated process flow. The technology of the black hole direct electroplating is produced in the background. The black hole direct electroplating technology is divided into a black hole technology and a black shadow technology, wherein the black hole technology uses carbon black as a conductive medium, utilizes the physical adsorption characteristic and the electric adsorption characteristic of the carbon black, deposits a layer of carbon black as a conductive layer on the hole wall of a glass fiber board with a drilled through hole of a circuit board, and then electroplates copper, thereby realizing interlayer communication; the black shadow technology is similar to the black shadow technology, graphite replaces conductive carbon black, the graphite is deposited on the hole wall of a glass fiber board of a drilled through hole of the printed circuit board to be used as a conductive layer, and then copper is electroplated, so that interlayer communication is realized. Both aims to provide a basic conductive base layer for copper plating on the wall of the through hole, and the process flow of the horizontal production line for manufacturing the black hole or the shadow of the printed circuit board is as follows:
cleaning whole hole → primary black hole → whole hole → secondary black hole → micro-etching → anti-oxidation → discharging material
The basic functions of the steps of the process flow are as follows:
cleaning the whole hole: a weakly alkaline composite aqueous solution is used to treat the via holes on the printed circuit board. On one hand, the method is used for removing scraps on the hole wall of the drilled hole and cleaning the hole wall, on the other hand, the active ingredients of the composite solution can adjust the surfaces of glass fibers and resin which originally have negative charges on the hole wall into surfaces with positive charges, so that the base material after the hole-finishing treatment can fully adsorb black liquid to form a uniform and compact conducting layer;
primary black hole: the conductive carbon black/fine graphite composite material mainly comprises conductive carbon black/fine graphite, a surfactant, deionized water and the like, wherein the conductive carbon black/fine graphite in the mixed solution is negatively charged. After the printed circuit board after cleaning treatment enters the groove, a layer of conductive carbon black/graphite is formed on the surface of the hole wall of the printed circuit board under the adsorption action of positive charges on the surface of the hole wall of the printed circuit board;
hole trimming: the whole hole is the repetition of the cleaning and whole hole process, and the main reason is that the electrical property of the glass fiber layer of the printed circuit board is not easy to change, and a carbon black/graphite layer meeting the requirements cannot be formed on the wall of the conducting hole of the printed circuit board by the black hole once, so secondary treatment is needed;
secondary black hole: the secondary black holes are repeated substantially in the primary black holes, so that a carbon black/graphite layer meeting the requirements is formed on the wall of the conducting hole of the printed circuit board;
micro-etching: in the process of pore formation, the carbon black/graphite can be adsorbed on the pore wall and also can be adsorbed on the inner copper ring and the surface of the copper-clad layer of the substrate, and in order to ensure that the electroplated copper has good binding force with the matrix copper, the carbon black/graphite on the copper layer needs to be removed. After the printed circuit board after the secondary black hole is put into the groove, the carbon black/graphite layer is slightly expanded by the microetching liquid to generate a micropore channel. The micro-pore channels of the micro-etching liquid are contacted with the copper layer of the printed circuit board, the copper surface is micro-etched by 1-2 mu m, the carbon black/graphite layer at the position is separated from the copper surface and falls off, and the carbon black/graphite layer on the non-conductor surface of the hole wall is kept in the original state, so that a good conductive layer is provided for direct electroplating.
Antioxidation: after the printed circuit board subjected to the microetching treatment enters the groove, passivating the copper-clad layer of the printed circuit board subjected to the microetching treatment by using a copper surface passivation liquid medicine;
discharging: and (4) transferring the printed circuit board subjected to the oxidation resistance treatment to a copper plating process.
The black hole direct electroplating technology comprises a black hole technology and a black shadow technology, overcomes the defects of a chemical copper deposition process, slowly replaces the traditional chemical copper deposition process, and brings great help to the upgrading and benefit improvement of the traditional circuit board processing. However, both of them have certain defects, especially in the double-sided printed circuit board and thick plate hole metallization, because the black hole technology uses carbon black as a conductive medium, limited by the conductivity of the carbon black material, after a conductive layer is formed on the hole wall of the glass fiber insulating board of the printed circuit board, the plating ability is not enough when copper is electroplated, so that the method can only be applied to the field of thin plates or soft plates; the black shadow technology uses graphite as a conductive medium, although the conductivity is better than that of carbon black, because the particle size of the graphite is larger (more than 1000nm), residual ink is easily formed on the wall of a copper-coated hole of a printed circuit board, and the subsequent reliability defect is caused; the two methods have the common defects that the manufacturing process is long, namely, secondary cleaning and secondary black holes are needed, and the production efficiency is low.
In order to solve the above problems, in the patent "aqueous solution of silver-carbon composite material and method for preparing the same, silver-carbon composite unit, electrical conductor, and method for preparing electrical conductor", a plurality of carbon materials are dispersed in water to form an aqueous solution, then the aqueous solution of silver salt is sprayed in the form of atomized droplets and added to the dispersion of carbon materials, and the resulting mixture is subjected to ultrasonic treatment to form the aqueous solution of silver-carbon composite material. The patent does not indicate whether it is suitable for a black hole direct plating process.
According to the patent, a black hole liquid and a silver nanowire are prepared firstly, the black hole liquid and the silver nanowire are mixed to form the circuit board conductive liquid, and the hole resistance of the circuit board is tested to be 1.6-1.9 kiloohms. The patent "a black hole reagent and black hole method for high-activity printed circuit board" only discloses the composition of the black hole reagent, and the preparation method is not described in detail. The patent "a water-soluble conductive nano metal carbon paste and conductive nano metal carbon film liner tube" grinds nonferrous metal powder with a particle size of 15-60 nm, conductive carbon black with a particle size of 100-1000 nm and a surfactant together, so that the nonferrous metal powder is embedded in the carbon black and dispersed in water, thereby forming the water-soluble conductive nano metal carbon paste, overcoming the defects of a black hole technology and a black shadow technology, improving the production efficiency, but only relying on the grinding effect to enable the metal powder to be embedded in the carbon black, and the method can be further improved. According to the patent, silver powder with the particle size of 5-60 nm, conductive carbon black with the particle size of 100-900 nm and a surfactant are ground together, so that the silver powder is embedded in the carbon black and dispersed in water, the water-soluble conductive nano silver carbon paste is formed, the defects of a black hole technology and a black shadow technology are overcome, the production efficiency is improved, the silver powder is embedded in the carbon black only by the grinding effect, and the method needs to be further improved.
Disclosure of Invention
In order to solve the problems, the invention provides a preparation method of conductive silver carbon paste. The method can ensure that silver is firmly adsorbed on the surface of carbon black in an atomic form, thoroughly overcome the defects of a black hole technology and a shadow technology, simplify the hole metallization preparation and improve the production efficiency.
The invention is realized by the following technical scheme:
a preparation method of conductive silver carbon paste comprises the following steps:
(1) soaking the nanoscale conductive carbon black in nitric acid, washing the nanoscale conductive carbon black to be neutral by using pure water, soaking the nanoscale conductive carbon black in hydrogen peroxide with the mass percentage concentration of 5% for 110-130 minutes, filtering, washing and drying for later use;
(2) adding the conductive carbon black treated in the step (1) into ethylene glycol, and performing ultrasonic dispersion for about 30 minutes; adding silver nitrate glycol solution, adding polyvinylpyrrolidone, stirring the mixed solution, and after the solution is uniformly dispersed, adjusting the pH value of the solution system to 9.8-10.2 by using alkaline solution;
(3) transferring the reaction solution into a hydrothermal reaction kettle for reaction, cooling to room temperature, filtering, washing and drying;
(4) placing the dried sample in a tubular furnace, and carrying out heat treatment in a reducing atmosphere to obtain silver-loaded nano carbon black, namely a silver-carbon composite;
(5) and finally, grinding and mixing the silver-carbon composite, the surfactant and pure water to obtain the conductive silver-carbon slurry.
Further, the particle size of the nano-scale conductive carbon black in the step (1) is 10-100 nm, and the preferable particle size is 20-50 nm.
Further, the conductive carbon black of step (1) may be selected from carbon black VUBCAN XC-72R and VUBCAN XC-72, superconductive carbon black PRINTEX XE2-B, Ketjenblack EC-300J, etc.
Further, the concentration of the nitric acid in the step (1) is 1.8-2.2 mol/L; the time of the nitric acid soaking treatment is 8-10 hours.
Further, in the step (2), the mass ratio of the silver to the conductive carbon black is 1 (1000-5000).
Further, the alkaline solution in the step (2) is 0.1mol/L of sodium hydroxide in glycol.
Further, the reaction temperature in the step (3) is 170-190 ℃, and the reaction time is 8-12 hours; and (4) drying at the temperature of 75-85 ℃ for 110-130 minutes in the step (3).
Further, the temperature of the heat treatment in the step (4) is 290-310 ℃, and the time is 110-130 minutes; and (4) the reducing atmosphere in the step (4) is a 10% hydrogen and 90% nitrogen atmosphere.
Further, the mass concentration of the silver-carbon composite in the step (5) is 10-50 g/L.
Further, the surfactant in the step (5) comprises a wetting agent, a penetrating agent, a dispersing agent, a blocking agent and a defoaming agent; the mass concentration of the surfactant is 0.1-1.0 g/L.
The mechanism of the conductive silver carbon paste is as follows: under the experimental conditions, silver ions are reduced and firmly adsorbed on the surface of the carbon black in a monomolecular layer form, so that the resistivity of the carbon black is greatly improved, and the consumption of silver is low; the silver-loaded carbon powder forms a stable dispersion system in water by grinding under the action of a surfactant.
The invention also provides application of the conductive silver carbon paste prepared by the preparation method in a printed circuit board. The method comprises the following steps:
(1) cleaning the whole hole. A weakly alkaline composite aqueous solution is used to treat the via holes on the printed circuit board. On one hand, the method is used for removing scraps on the hole wall of the drilled hole and cleaning the hole wall, on the other hand, the active ingredients of the composite solution can adjust the surfaces of glass fibers and resin which originally have negative charges on the hole wall into surfaces with positive charges, so that the base material after the hole-finishing treatment can fully adsorb black liquid to form a uniform and compact conducting layer;
(2) and (4) black holes. After the printed circuit board after cleaning treatment enters the groove, the conductive carbon black loaded with silver and having negative charges in the conductive silver carbon slurry can be firmly and uniformly deposited on the surface of the hole wall of the printed circuit board under the adsorption action of the positive charges on the surface of the hole wall of the printed circuit board to form a conductive layer;
(3) and (7) micro-etching. In the process of pore formation, carbon black is adsorbed on the pore walls and also on the surfaces of the inner copper ring and the copper-clad layer of the substrate, and in order to ensure that the electroplated copper has good binding force with the matrix copper, the carbon black/graphite on the copper layer needs to be removed. After the printed circuit board after the secondary black hole is put into the groove, the carbon black layer is slightly expanded by the microetching liquid, and a micropore channel is generated. The micro-pore channels of the micro-etching liquid are contacted with the copper layer of the printed circuit board, the copper surface is micro-etched by 1-2 mu m, the carbon black/graphite layer at the position is separated from the copper surface and falls off, and the carbon black/graphite layer on the non-conductor surface of the hole wall is kept in the original state, so that a good conductive layer is provided for direct electroplating.
(4) And (4) oxidation resistance. After the printed circuit board subjected to the microetching treatment is put into the tank, passivating the copper-clad plate of the microetching printed circuit board by using a copper surface passivation liquid medicine;
(5) and (6) discharging. And (4) transferring the printed circuit board subjected to the oxidation resistance treatment to a copper plating process.
The invention adopts the technical scheme that the beneficial effects are as follows:
(1) the conductive carbon film formed by the conductive silver carbon paste reaches the level of a conductive level, provides a conductive silver carbon layer superior to a conductive carbon layer formed by carbon black or graphite for the metallization of the pore wall of a glass fiber layer of a printed circuit board, simplifies the black pore manufacturing process, can achieve the effect by blackening once, and improves the production efficiency.
(2) The preparation method provided by the invention can ensure that silver is firmly adsorbed on the surface of carbon black in an atomic form, and thoroughly solves the defects of a black hole technology and a black shadow technology.
Detailed Description
The technical solutions of the present invention will be further described in detail with reference to examples, but the scope of the present invention is not limited to the scope shown in the examples.
Example 1
A method of making a conductive silver carbon paste, the method comprising the steps of:
(1) 100g of Germany superconducting carbon black PRINTEX XE2-B (the grain diameter is 30nm) is added into 2mol/L nitric acid to be soaked for 9 hours and washed by pure water to be neutral; soaking the mixture for 2 hours by using hydrogen peroxide with the mass percentage concentration of 5 percent, filtering, washing and drying the mixture for later use;
(2) adding the conductive carbon black treated in the step (1) into ethylene glycol for ultrasonic dispersion for 30 minutes; adding 10mL of silver nitrate glycol solution (the mass concentration is 15.8g/L), adding 10mL of polyvinylpyrrolidone, stirring the mixed solution, and after the solution is uniformly dispersed, adjusting the pH value of the solution system to 9.8-10.2 by using 0.1mol/L of sodium hydroxide glycol solution;
(3) transferring the reaction liquid into a hydrothermal reaction kettle, reacting for 11 hours at 180 ℃, cooling to room temperature, filtering, washing, and vacuum drying for 2 hours at 80 ℃;
(4) placing the dried sample in a tube furnace, and carrying out heat treatment for 120 minutes at 300 ℃ in an atmosphere of 10% hydrogen and 90% nitrogen to obtain a silver-carbon composite;
(5) adding the silver-carbon complex and surfactant (including sodium dodecyl benzene sulfonate, fatty alcohol-polyoxyethylene ether, fatty alcohol-polyoxyethylene sulfate, polyvinyl alcohol and acetone) into pure water. Wherein the mass concentration of the silver-carbon composite is 10 g/L; and the mass concentration of the surfactant is 0.1g/L, and the conductive silver carbon slurry is obtained by grinding and mixing for 2 hours by using a ball mill.
Example 2
A method of making a conductive silver carbon paste, the method comprising the steps of:
(1) 100g of carbon black VULCAN XC-72R (particle size 50nm) is added into 1.8mol/L nitric acid to be soaked for 10 hours and is washed to be neutral by pure water; soaking the mixture for 2 hours by using hydrogen peroxide with the mass percentage concentration of 5 percent, filtering, washing and drying the mixture for later use;
(2) adding the conductive carbon black treated in the step (1) into ethylene glycol, and performing ultrasonic dispersion for about 30 minutes; adding 4mL of silver nitrate glycol solution (the mass concentration is 15.8g/L), adding 10mL of polyvinylpyrrolidone, stirring the mixed solution, and after the solution is uniformly dispersed, adjusting the pH value of the solution system to 9.8-10.2 by using 0.1mol/L of sodium hydroxide glycol solution;
(3) transferring the reaction liquid into a hydrothermal reaction kettle, reacting for 12 hours at 170 ℃, cooling to room temperature, filtering, washing, and vacuum drying for 130 minutes at 75 ℃;
(4) placing the dried sample in a tube furnace, and carrying out heat treatment for 130 minutes in an atmosphere of 10% hydrogen and 90% nitrogen at 290 ℃ to obtain a silver-carbon composite;
(5) adding the sample and surfactant (including sodium dodecyl benzene sulfonate, fatty alcohol-polyoxyethylene ether, fatty alcohol-polyoxyethylene sulfate, polyvinyl alcohol, and acetone) into pure water. Wherein the mass concentration of the silver-carbon composite is 30 g/L; and the mass concentration of the surfactant is 0.5g/L, and the conductive silver carbon slurry is obtained by grinding and mixing for 2 hours by using a ball mill.
Example 3
A method of making a conductive silver carbon paste, the method comprising the steps of:
(1) 100g of Ketjenblack EC-300J (particle size 50nm) of Japanese Ketjenblack is added into 2.2mol/L nitric acid to be soaked for 8 hours and washed to be neutral by pure water; soaking the mixture for 2 hours by using hydrogen peroxide with the mass percentage concentration of 5 percent, filtering, washing and drying the mixture for later use;
(2) adding the conductive carbon black treated in the step (1) into ethylene glycol, and performing ultrasonic dispersion for 30 minutes; adding 2mL of silver nitrate glycol solution (the mass concentration is 15.8g/L), adding 10mL of polyvinylpyrrolidone, stirring the mixed solution, and after the solution is uniformly dispersed, adjusting the pH value of the solution system to 9.8-10.2 by using 0.1mol/L of sodium hydroxide glycol solution;
(3) transferring the reaction liquid into a hydrothermal reaction kettle, reacting for 10 hours at 190 ℃, cooling to room temperature, filtering, washing, and vacuum drying for 110 minutes at 85 ℃;
(4) placing the dried sample in a tube furnace, and carrying out heat treatment for 110 minutes at the temperature of 310 ℃ in the atmosphere of 10% hydrogen and 90% nitrogen to obtain a silver-carbon composite;
(5) adding the sample and surfactant (including sodium dodecyl benzene sulfonate, fatty alcohol-polyoxyethylene ether, fatty alcohol-polyoxyethylene sulfate, polyvinyl alcohol, and acetone) into pure water. Wherein the mass concentration of the silver-carbon composite is 50 g/L; and the mass concentration of the surfactant is 1.0g/L, and the conductive silver carbon slurry is obtained by grinding and mixing for 2 hours by using a ball mill.
Application example 1
A method for manufacturing black holes in printed circuit board holes by using conductive silver carbon paste comprises the following steps:
(1) and (4) cleaning. Processing the printed circuit board with the drilled holes by using a commercially available cleaning and pore-finishing agent;
(2) and (4) black holes. Putting the printed circuit board after the cleaning treatment into the black hole groove filled with the conductive silver carbon paste prepared in the embodiment, and performing black hole treatment;
(3) and (5) micro-etching. Treating the printed circuit board by adopting a commercially available microetching solution;
(4) and (4) oxidation resistance. Treating the printed circuit board by using commercially available antioxidant liquid;
(5) cleaning, drying and discharging.
Comparative example 1
(1) And (4) cleaning. Processing the printed circuit board with the drilled holes by using a commercially available cleaning and hole-trimming agent;
(2) and (4) black holes. Putting the printed circuit board after the cleaning treatment into a black hole groove filled with a black hole liquid sold in the market, and carrying out black hole treatment;
(3) and (5) micro-etching. Treating the printed circuit board by adopting a commercially available microetching solution;
(4) and (4) oxidation resistance. Treating the printed circuit board by using commercially available antioxidant liquid;
(5) cleaning, drying and discharging.
Comparative example 2
(1) And (4) cleaning. Processing the printed circuit board with the drilled holes by using a commercially available cleaning and hole-trimming agent;
(2) and (5) performing black hole treatment. Placing the printed circuit board after cleaning treatment into a black hole groove filled with a commercially available black hole liquid, and performing black hole treatment;
(3) and (4) hole preparation. Treating the printed circuit board treated in the step (2) by using a commercially available pore-forming agent;
(4) and (5) secondary black hole forming. Repeating the black hole operation for one time;
(5) and (5) micro-etching. Treating the printed circuit board by adopting a commercially available microetching solution;
(6) and (4) oxidation resistance. Treating the printed circuit board by using commercially available antioxidant liquid;
(7) cleaning, drying and discharging.
Comparative experiment 1
Manufacturing a test board: FR4 double-sided board, thickness of 1.6 mm, area of 60 × 100 mm, 0.3 mm hole 20, 0.5 mm hole 20, 1.0 mm hole 20.
The experimental results are as follows:
by applying example 1, 60 holes were plated through and the surface resistance of the conductive film was 10 ohms.
Comparative example 1, which was prepared as described above, 7 holes were not plated through, and the surface resistance of the conductive film was 5000 ohms.
Comparative example 2, prepared as described above, had 3 holes and light micro-cracks, and the surface resistance of the conductive film was 1000 ohms.
Comparative experiment 2
Cutting into a length of 10cm and a cross-sectional area of 1cm2The high-density sponge is soaked in a black pore liquid sold in the market, and after the sponge is fully extruded and dried, the resistance of the two ends of the sponge is measured to be 30 kiloohms.
Cutting to obtain a product with a length of 10cm and a cross-sectional area of 1cm2The high-density sponge prepared in the example was immersed in the conductive silver carbon paste, sufficiently extruded and dried, and then the resistance at both ends was measured to be 800 ohms.
From the results of comparative experiment 1, it can be found that: compared with the commercially available black pore liquid, the conductive silver carbon paste prepared by the invention simplifies the black pore preparation process under the same conditions, and the formed carbon film has lower resistance. From the results of comparative experiment 2, it can be found that: compared with the commercial black pore liquid, the resistance of the carbon film formed by the conductive silver carbon paste prepared by the invention is reduced to 2.7% under the same conditions.
Experiments prove that the conductive carbon film formed by the conductive silver carbon paste reaches the level of the conductive level, provides a conductive silver carbon film superior to the conductive carbon film formed by carbon black/graphite for metallization of the pore wall of the glass fiber layer of the printed circuit board, and can achieve the effect by blackening once. The silver is firmly adsorbed on the surface of the carbon black in an atomic form, so that the defects of a black hole technology and a black shadow technology are thoroughly overcome, the black hole manufacturing procedure is simplified, and the production efficiency is improved.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims (10)

1. The preparation method of the conductive silver carbon paste is characterized by comprising the following steps:
(1) soaking the nanoscale conductive carbon black in nitric acid, washing with pure water to neutrality, soaking with hydrogen peroxide, filtering, washing, and drying;
(2) adding the conductive carbon black treated in the step (1) into ethylene glycol for ultrasonic dispersion; adding silver nitrate glycol solution, adding polyvinylpyrrolidone, stirring the mixed solution, and adjusting the pH value of the solution system by using alkaline solution after the solution is uniformly dispersed;
(3) transferring the reaction solution into a hydrothermal reaction kettle for reaction, cooling to room temperature, filtering, washing and drying;
(4) placing the dried sample in a tubular furnace, and carrying out heat treatment in a reducing atmosphere to obtain silver-loaded nano carbon black, namely a silver-carbon composite;
(5) and finally, grinding and mixing the silver-carbon composite, the surfactant and pure water to obtain the conductive silver-carbon slurry.
2. The method for preparing conductive silver carbon paste according to claim 1, wherein the particle size of the nano-scale conductive carbon black in the step (1) is 10-100 nm.
3. The method for preparing conductive silver carbon paste according to claim 1, wherein the concentration of the nitric acid in the step (1) is 1.8-2.2 mol/L; the time of the nitric acid soaking treatment is 8-10 hours.
4. The method for preparing the conductive silver carbon paste according to claim 1, wherein in the step (2), the mass ratio of the silver to the conductive carbon black is 1 (1000-5000).
5. The method for preparing conductive silver carbon paste according to claim 1, wherein the alkaline solution in the step (2) is 0.1mol/L of sodium hydroxide in ethylene glycol; the pH of the solution system is adjusted to 9.8-10.2.
6. The method for preparing conductive silver carbon paste according to claim 1, wherein the reaction temperature in the step (3) is 170-190 ℃, and the reaction time is 8-12 hours; and (4) drying at the temperature of 75-85 ℃ for 110-130 minutes in the step (3).
7. The method for preparing conductive silver carbon paste according to claim 1, wherein the temperature of the heat treatment in the step (4) is 290-310 ℃ and the time is 110-130 minutes; and (4) the reducing atmosphere in the step (4) is a 10% hydrogen and 90% nitrogen atmosphere.
8. The method for preparing conductive silver carbon paste according to claim 1, wherein the mass concentration of the silver carbon composite in the step (5) is 10-50 g/L.
9. The method for preparing conductive silver carbon paste according to claim 1, wherein the surfactant in the step (5) comprises a wetting agent, a penetrating agent, a dispersing agent, a blocking agent, an antifoaming agent; the mass concentration of the surfactant is 0.1-1.0 g/L.
10. Use of the conductive silver carbon paste prepared by the preparation method according to any one of claims 1 to 9 in a printed circuit board.
CN202210447063.6A 2022-04-26 2022-04-26 Preparation method and application of conductive silver carbon paste Pending CN114724772A (en)

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