A modified micro-etching solution and a method for treating carbon powder in the micro-etching solution for the circuit board industry

Abstract

The present invention provides a modified micro-etching solution and a method for treating carbon powder in the micro-etching solution for the circuit board industry. The method comprises the following steps: treating the micro-etching solution containing carbon powder with a mixed acid solution, ultrasonicating, and obtaining a pre-treated carbon powder micro-etching solution; mixing the pre-treated carbon powder micro-etching solution with an activation solution under an inactive atmosphere, refluxing, centrifuging, and drying, to obtain a surface-activated carbon powder micro-etching solution; and subjecting the surface-activated carbon powder micro-etching solution to three-stage gradient polymerization with a mixture containing aniline monomer, ammonium persulfate, and dodecylbenzenesulfonic acid, to obtain a modified micro-etching solution. The modified micro-etching solution provided by the present invention has improved electrolysis efficiency, with a copper recovery rate increased from 78% to 92%; enhanced process stability, with fluctuations in carbon powder concentration within ±5%; extended equipment life, and its anode maintenance cycle can be extended from 200 hours to 1500 hours; and increased recycling rate to 85%, significantly improving environmental benefits.

Description

Technical Field

[0001] The invention provides a modified micro-etching solution and a method for treating carbon powder in the micro-etching solution in the circuit board industry, belonging to the technical field of printed circuit board manufacturing. Background Art

[0002] Black hole technology involves depositing a layer of high-quality, black, conductive nanocarbon on the hole walls. This layer's excellent conductivity is then used for subsequent electroplating. It's a critical process in circuit board manufacturing. Currently, the following technologies are commonly used in PCB black hole production: 1. Physical adsorption: Carbon black / graphite particles are directly adsorbed onto the hole walls to form a conductive layer; 2. Chemical modification: Silane coupling agent surface treatment improves dispersion; and 3. Mechanical filtration: Filtering suspended carbon powder using a bag or filter element.

[0003] The existing PCB black hole process technology has the following defects: 1. Conductive carbon powder migration problem: 0.2-0.3μm carbon powder is driven by the electric field to migrate in a directional manner during electrolysis (migration rate> 0.5cm 2 / (V·s)); 2. Anode carbon film accumulation: A conductive carbon film (resistivity <10 3 Ω·m), resulting in a short circuit between the anode and cathode; 3. Insufficient surface modification: Traditional modifiers only improve dispersibility but fail to block the conductive path (surface resistance increases by less than two orders of magnitude); 4. Poor process stability: Fixed electrolysis parameters lead to fluctuations in carbon powder concentration exceeding ±30%; 5. Micro-etching solution reuse rate is less than 35%. Therefore, the present invention provides a treatment method for improving the conductive properties of carbon powder in the micro-etching solution of the black hole process through surface modification technology, which is used to solve the short circuit problem caused by conductive carbon powder migration during electrolytic copper extraction. Summary of the Invention

[0004] Based on the above technical deficiencies, the present invention provides a treatment method for improving the conductive properties of carbon powder in black hole micro-etching solution through surface modification technology, which is used to solve the short circuit problem caused by the conductive migration of carbon powder during electrolytic copper extraction. The present invention forms a 50-100nm polyaniline coating on the surface of the carbon powder in the modified micro-etching solution through a gradient grafting process. It innovatively adopts impedance feedback control (accuracy ±0.5%) and three-stage temperature control (0-25℃), combined with a three-stage filtration system (200μm→0.5μm). After treatment, the surface resistance of the modified micro-etching solution reaches 1.8×10 8 Ω·m, electrolytic copper purity of 99.2%, and modified micro-etching liquid recycling rate of 85%; it solves the short circuit problem caused by carbon powder conductive migration during the electrolytic copper extraction process of PCB black hole process micro-etching liquid.

[0005] The technical problems to be solved by the present invention are: 1. cutting off the conductive migration path of carbon powder, 2. eliminating the accumulation of carbon film on the anode surface, 3. improving the stability of the electrolysis process and 4. realizing online regeneration of the micro-etching solution.

[0006] According to one aspect of the present invention, a method for treating carbon powder in micro-etching liquid in the circuit board industry is provided, the method comprising the following steps:

[0007] Step S1: treating the micro-etching solution containing carbon powder with a mixed acid solution and ultrasonicating to obtain a pre-treated carbon powder micro-etching solution;

[0008] Step S2: In an inactive atmosphere, the pre-treated carbon powder micro-etching solution is mixed with the activation solution, refluxed, centrifuged, and dried to obtain a surface-activated carbon powder micro-etching solution;

[0009] Step S3: The carbon powder micro-etching solution subjected to surface activation treatment is subjected to three-stage gradient polymerization with a mixture containing aniline monomer, ammonium persulfate, and dodecylbenzenesulfonic acid to obtain a modified micro-etching solution.

[0010] Optionally, in step S1 , the liquid-to-solid ratio of the mixed acid solution to the micro-etching solution containing carbon powder is 3:1 to 8:1.

[0011] Optionally, in step S1 , the liquid-to-solid ratio of the mixed acid solution to the carbon powder-containing micro-etching solution is independently selected from any value of 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, or a range between any two of the above values.

[0012] Optionally, the mixed acid includes concentrated sulfuric acid and concentrated nitric acid, and the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1.

[0013] Optionally, the ultrasonic temperature is 50-70° C., the ultrasonic time is 20-40 min, and the ultrasonic power density is 80-150 W / L.

[0014] Optionally, the temperature of ultrasound is independently selected from any value among 50°C, 55°C, 60°C, 65°C, 70°C or a range between any two of the above values.

[0015] Optionally, the ultrasound time is independently selected from any value among 20 min, 25 min, 30 min, 35 min, 40 min or a range between any two of the above.

[0016] Optionally, the power density of the ultrasound is any value among 80W / L, 90W / L, 100W / L, 110W / L, 120W / L, 130W / L, 140W / L, 150W / L, or a range between any two of the above values.

[0017] Optionally, in step S2, the activation solution includes γ-aminopropyltriethoxysilane, tetraethoxysilane and ethanol.

[0018] Optionally, the mass percentage of γ-aminopropyltriethoxysilane in the activation solution is 2.0-3.0 wt.%.

[0019] Optionally, the mass percentage of tetraethoxysilane in the activation solution is 0.5-1.0 wt.%.

[0020] Optionally, the solid-to-liquid ratio of the pre-treated carbon powder micro-etching solution to the activation solution is 1:10 to 1:15.

[0021] Optionally, in step S2, the inert atmosphere is selected from at least one of nitrogen, argon, and helium.

[0022] Optionally, the reflux temperature is 75-85° C., and the reflux time is 1.5-2.5 h.

[0023] Optionally, the reflux temperature is independently selected from any value among 75°C, 76°C, 78°C, 80°C, 82°C, 85°C or a range between any two of the above values.

[0024] Optionally, the reflux time is independently selected from any value among 1.5h, 1.8h, 2h, 2.2h, 2.5h or a range between any two of the above values.

[0025] Optionally, the drying temperature is 50-80° C., and the drying time is 4-8 hours.

[0026] Optionally, in step S3, the concentration of aniline monomer is 0.3-0.8 mol / L, and the concentration of ammonium persulfate is 0.15-0.4 mol / L.

[0027] Optionally, in step S3, the concentration of the aniline monomer is independently selected from any value among 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, or a range between any two of the above values.

[0028] Optionally, the concentration of ammonium persulfate is independently selected from any value among 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, or a range between any two of the above values.

[0029] Optionally, in step S3, the three-stage gradient polymerization includes a pre-oxidation stage, a chain growth stage and a cross-linking stage.

[0030] Optionally, in step S3, a pre-oxidation stage is carried out after adding aniline monomer, a chain growth stage is carried out after adding ammonium persulfate and the temperature is raised, and a cross-linking stage is carried out after adding dodecylbenzenesulfonic acid. The chain growth stage plays a key role in the orderly arrangement of the molecular chains. The absence of the chain growth stage will result in a disordered molecular chain structure of the modified carbon powder, which cannot meet the use requirements.

[0031] Optionally, the temperature of the pre-oxidation stage is 0-5° C., and the time of the pre-oxidation stage is 30-45 minutes.

[0032] Optionally, the temperature of the pre-oxidation stage is independently selected from any value of 0°C, 1°C, 2°C, 3°C, 4°C, 5°C or a range between any two of the above values.

[0033] Optionally, the time of the pre-oxidation stage is independently selected from any value among 30 min, 32 min, 35 min, 40 min, 45 min or a range between any two of the above.

[0034] Optionally, the temperature of the chain extension stage is 15-20° C., and the time of the chain extension stage is 60-120 min.

[0035] Optionally, the temperature of the chain extension stage is independently selected from any value among 15°C, 16°C, 17°C, 18°C, 19°C, 20°C or a range between any two of the above values.

[0036] Optionally, the duration of the chain extension phase is independently selected from any value among 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, 120 min, or a range between any two of the above.

[0037] Optionally, the temperature of the cross-linking stage is 25-28° C., and the time of the cross-linking stage is 100-150 min.

[0038] Optionally, the temperature of the cross-linking stage is independently selected from any value among 25°C, 26°C, 27°C, 28°C or a range between any two of the above values.

[0039] Optionally, the time of the cross-linking stage is independently selected from any value among 100 min, 110 min, 120 min, 130 min, 140 min, 150 min or a range between any two of the above values.

[0040] Optionally, in step S3, the added concentration of dodecylbenzenesulfonic acid is 0.08-0.15 mol / L.

[0041] Optionally, in step S3, the added concentration of dodecylbenzenesulfonic acid is independently selected from any value among 0.08 mol / L, 0.09 mol / L, 0.10 mol / L, 0.11 mol / L, 0.12 mol / L, 0.13 mol / L, 0.14 mol / L, 0.15 mol / L, or a range between any two of the above values.

[0042] Optionally, during the cross-linking stage, the pH value of the reaction system needs to be controlled to be 1.3-1.7.

[0043] Optionally, during the cross-linking stage, the pH value of the reaction system needs to be controlled to be independently selected from any value among 1.3, 1.4, 1.5, 1.6, 1.7, or a range between any two of the above values.

[0044] Optionally, after the cross-linking stage, NaOH solution is added to adjust the pH value of the reaction system to 9.0-10.5 at a rate of 0.5-1.5 pH / min.

[0045] According to another aspect of the present application, a modified micro-etching solution prepared by the above-mentioned treatment method is provided, wherein the thickness of the polyaniline coating layer coated on the surface of the carbon powder in the modified micro-etching solution is 50-100 nm.

[0046] Optionally, the porosity of the polyaniline coating layer is 15-30%, the average pore size of the polyaniline coating layer is 3-10 nm, and the specific surface area of ​​the polyaniline coating layer is 50-80 m 2 / g.

[0047] Optionally, the surface resistivity of the modified micro-etching solution is ≥1×10 8 Ω·m, the Zeta potential of the modified micro-etching solution is -35mV~-40mV, and the electrolytic mobility of the modified micro-etching solution is less than 0.05cm 2 / (V·s).

[0048] Optionally, the modified micro-etching solution has a dispersion stability of >48h at a pH value of 1.0-2.0.

[0049] As an optional embodiment, the present invention is implemented by the following technical solutions:

[0050] A method for treating carbon powder in micro-etching liquid in the circuit board industry comprises the following steps:

[0051] (a) Acid pretreatment of the microetching solution containing carbon powder: using a mixed acid system with a volume ratio of H2SO4 to HNO3 of 3:1, ultrasonic treatment was performed at a temperature of 50-70°C for 20-40 minutes;

[0052] (b) Surface activation treatment: using an ethanol solution containing γ-aminopropyltriethoxysilane and tetraethoxysilane at a concentration of 2.0-3.0 wt%, reflux at 75-85°C under nitrogen protection for 1.5-2.5 hours, centrifuge, and dry;

[0053] (c) In situ graft polymerization: A three-stage gradient temperature polymerization was carried out in a reaction system containing aniline monomer concentrations of 0.3-0.8 mol / L, ammonium persulfate concentrations of 0.15-0.4 mol / L, and dodecylbenzenesulfonic acid concentrations of 0.08-0.15 mol / L, with the pH of the reaction system controlled within the range of 1.3-1.7;

[0054] (d) Dedoping and curing: NaOH solution is added to adjust the pH value of the reaction system to 9.0-10.5. The pH value adjustment converts the polyaniline into an insulating state, forming a nanoscale coating layer of 50-100 nm.

[0055] Optionally, in step (a), the ultrasonic treatment uses a titanium alloy ultrasonic treatment tank, the frequency range of the ultrasonic treatment tank is 40±5kHz, and the volume is 300-800L.

[0056] Optionally, in steps (b), (c), and (d), the reactions are carried out in a fluidized bed reactor. The parameters of the fluidized bed reactor are: diameter Φ800-1500 mm, and material 316L stainless steel or Hastelloy C276.

[0057] Optionally, in step (c), a gradient temperature control system is used in the gradient temperature polymerization, and the parameters of the gradient temperature control system are: temperature control accuracy ±0.5°C, and temperature adjustment range -10°C to 80°C.

[0058] Optionally, the gradient temperature control system includes a segmented graphite coil heat exchanger, and each temperature zone has an independent temperature control accuracy of ±0.3°C.

[0059] Optionally, in step (b), after reflow, a vacuum drying unit is used for drying, and the parameters of the vacuum drying unit are: working pressure ≤ 50 Pa, equipped with a microwave-assisted heating device (frequency 2450±50 MHz).

[0060] Optionally, the vacuum drying unit is equipped with an online moisture monitor with a detection accuracy of ±0.1% moisture content.

[0061] Optionally, the surface resistivity of the modified micro-etching solution is ≥1×10 8 Ω·m (ASTM D257 standard measurement), Zeta potential is stable at -35mV to -40mV (measured at pH=1.5), electrolytic mobility is less than 0.05cm 2 / (V·s)(0.5A / dm 2 electric field strength).

[0062] Optionally, the modified micro-etching solution has a dispersion stability of >48 hours (particle size change rate <5%) in an environment with a pH of 1.0-2.0.

[0063] Optionally, the modified micro-etching solution is applied to a pulse electrolytic copper extraction device (switching cycle 25-35s forward / 3-8s reverse), a three-stage gradient filtration module (200μm metal filter → 1μm ceramic membrane → 0.5μm electrophoresis filter element).

[0064] Optionally, the modified micro-etching solution is applied to a pulse electrolysis device equipped with: a titanium-plated iridium anode plate (iridium content 15-20wt%); a 316L stainless steel cathode plate; and an online impedance monitoring module (detection frequency 1kHz-100kHz).

[0065] Optionally, when the modified micro-etching solution is used, a cyclone electrophoresis pretreatment unit is also provided. The technical parameters include: electric field strength 500-1000 V / m; centrifugal factor 80-150 G; processing flow rate 5-15 m 3 / h.

[0066] The beneficial effects that the present invention can produce include:

[0067] 1) The present invention forms a 50-100nm polyaniline coating on the surface of carbon powder in the modified micro-etching solution through a gradient grafting process. The invention innovatively adopts impedance feedback control (accuracy ±0.5%) and three-stage temperature control (0-25°C), combined with a three-stage filtration system (200μm→0.5μm). Through the three-stage temperature control, the micro-etching solution containing carbon powder can be modified through the pre-oxidation stage, chain growth stage and cross-linking stage, so that the molecular chains in the modified micro-etching solution grow in an orderly manner. The electrolysis efficiency of the modified micro-etching solution after treatment is improved, and its copper recovery rate is increased from 78% to 92% (Cu 2+ 40g / L working conditions), the electrolytic copper purity is 99.2%, which solves the short circuit problem caused by the conductive migration of carbon powder in the electrolytic copper extraction process; the process stability of the modified micro-etching solution is enhanced, and the fluctuation of the carbon powder concentration is controlled within ±5%; the use of the modified micro-etching solution can extend the life of the equipment and extend its anode maintenance cycle from 200h to 1500h; the reuse rate of the modified micro-etching solution prepared by the present invention is increased to 85%, which can significantly improve environmental benefits.

[0068] 2) The modified micro-etching solution prepared by the method for treating carbon powder in micro-etching solution for circuit board industry provided by the present invention has a surface resistivity of 1.8×10 8 Ω·m compared to the surface resistivity of the micro-etching solution prepared by the traditional process of 2.5×10 5The Ω·m was increased by 719 times; the copper recovery rate of the modified micro-etching solution in the electrolytic copper extraction process was 92%, an increase of 18% compared to the copper recovery rate of 78% of the micro-etching solution prepared by the traditional process; the maintenance cycle of the modified micro-etching solution was 1500 hours, an increase of 650% compared to the maintenance cycle of 200 hours of the micro-etching solution prepared by the traditional process; the reuse rate of the modified micro-etching solution was 85%, an increase of 183% compared to the reuse rate of 30% of the micro-etching solution prepared by the traditional process. DETAILED DESCRIPTION

[0069] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0070] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0071] Example 1

[0072] Experimental Materials:

[0073] Micro-etching liquid containing carbon powder: taken from the black hole process waste liquid of PCB factory, D 50 =0.25μm, specific surface area 85m 2 / g.

[0074] Chemical reagents:

[0075] Mixed acid system: concentrated sulfuric acid (98%) and concentrated nitric acid (65%) prepared in a volume ratio of 3:1; aniline monomer: Aladdin reagent, purity ≥99.5%, purified by vacuum distillation; SDBS (sodium dodecylbenzenesulfonate): Comeo Chemical, analytical grade.

[0076] Main equipment:

[0077] Ultrasonic processor: Sonics VCX750 (20-40 kHz adjustable); polymerization reactor: 500 mL jacketed glass reactor (with mechanical stirring); freeze dryer: Labconco FreeZone 4.5 L.

[0078] Process implementation steps

[0079] Step 1: Pre-treat the micro-etching solution containing carbon powder with acid

[0080] 1. Take 200g of micro-etching solution containing carbon powder and add it to mixed acid solution (H2SO4:HNO3=3:1 v / v), with a liquid-to-solid ratio of 5:1;

[0081] 2. Turn on ultrasonic treatment (40kHz, power density 100W / L) at 60℃ for 30 minutes to evenly mix the micro-etching solution containing carbon powder and the mixed acid solution;

[0082] 3. Treat with a polymerization reactor at 60°C for 30 minutes;

[0083] 4. Wash with deionized water after vacuum filtration until neutral. After the conductivity of the pre-treated carbon powder micro-etching solution is less than 5μS / cm, perform surface activation treatment.

[0084] Step 2: Surface activation

[0085] 1. Prepare activation solution: APTES (γ-aminopropyltriethoxysilane) 2.5wt%; TEOS (tetraethoxysilane) 0.8wt%; ethanol / water = 95 / 5 (v / v);

[0086] 2. Mix the pretreated carbon powder micro-etching solution and the activation solution in a solid-liquid ratio of 1:10; 3. Reflux at 80°C for 2 hours under nitrogen protection; 4. Centrifuge and vacuum dry at 60°C for 6 hours to obtain the surface activated carbon powder micro-etching solution.

[0087] Step 3: In situ graft polymerization

[0088] Aniline monomer with a concentration of 0.5 mol / L was prepared and pre-cooled to 0°C for use; a surface activated carbon powder micro-etching solution was added and pre-oxidized at 0°C. After stirring at 300 rpm for 30 minutes, ammonium persulfate with a concentration of 0.25 mol / L was slowly added dropwise to the aniline monomer at a rate of 1 mL / min, the temperature was raised to 15°C, and the reaction was carried out at 500 rpm for 90 minutes; then sodium dodecylbenzene sulfonate (SDBS) with a concentration of 0.12 mol / L was added, the pH value of the reaction was controlled to 1.5, the temperature was raised to 25°C again, and the reaction was carried out at 200 rpm for 120 minutes. NaOH solution was added to adjust the pH value of the system to 9.5 at a rate of 0.5 pH / min. After the reaction, the product was collected by centrifugation to obtain a modified micro-etching solution. The nano-scale coating layer on the surface of the carbon powder in the micro-etching solution was 80 nm, the porosity of the polyaniline coating layer was 20%, the average pore size was 8 nm, and the specific surface area was 60 m 2 / g;

[0089] Step 4: Post-processing and characterization

[0090] 1. The modified micro-etching solution was freeze-dried under vacuum freeze-drying conditions (-50°C, 10Pa, 24h), and then subjected to particle size analysis and electrochemical performance testing. The specific testing equipment and conditions are as follows:

[0091] 2. Particle size analysis: Mastersizer 3000 laser particle size analyzer;

[0092] 3. Electrochemical test: PARSTAT 4000 electrochemical workstation.

[0093] The specific experimental results after testing are shown in Table 1 below.

[0094] Table 1: Comparison of performance parameters of micro-etching fluid before and after modification

[0095]

[0096] It can be seen from Table 1 that the surface resistivity of the modified micro-etching solution is 1.8×10 8 Ω·m; the copper recovery rate of the modified micro-etching solution in the electrolytic copper extraction process was 92%, which was 14% higher than the copper recovery rate of 78% of the micro-etching solution before modification; the agglomeration index of the modified micro-etching solution was 1.12, and the Zeta potential (pH=1.5) of the modified micro-etching solution was -38mV, compared with -25mV of the micro-etching solution before modification. The larger the absolute value of the Zeta potential, the stronger the electrostatic repulsion between particles and the more stable the dispersion system.

[0097] Example 2

[0098] Experimental Materials:

[0099] Micro-etching liquid containing carbon powder: taken from the black hole process waste liquid of PCB factory, D 50 =0.25μm, specific surface area 85m 2 / g.

[0100] Chemical reagents:

[0101] Mixed acid system: concentrated sulfuric acid (98%) and concentrated nitric acid (65%) prepared in a volume ratio of 3:1; aniline monomer: Aladdin reagent, purity ≥99.5%, purified by vacuum distillation; SDBS (sodium dodecylbenzenesulfonate): Comeo Chemical, analytical grade.

[0102] Main equipment:

[0103] Ultrasonic processor: Sonics VCX750 (20-40 kHz adjustable); polymerization reactor: 500 mL jacketed glass reactor (with mechanical stirring); freeze dryer: Labconco FreeZone 4.5 L.

[0104] Process implementation steps

[0105] Step 1: Pre-treat the micro-etching solution containing carbon powder with acid

[0106] 1. Take 200g of micro-etching solution containing carbon powder and add it to mixed acid solution (H2SO4:HNO3=3:1 v / v), with a liquid-to-solid ratio of 3:1;

[0107] 2. Turn on ultrasonic treatment (40kHz, power density 80W / L) at 70℃ for 20 minutes to evenly mix the micro-etching solution containing carbon powder and the mixed acid solution;

[0108] 3. Treat with a polymerization reactor at a constant temperature of 50°C for 40 minutes;

[0109] 4. Wash with deionized water after vacuum filtration until neutral. After the conductivity of the pre-treated carbon powder micro-etching solution is less than 5μS / cm, perform surface activation treatment.

[0110] Step 2: Surface activation

[0111] 1. Prepare activation solution: APTES (γ-aminopropyltriethoxysilane) 2.0wt%; TEOS (tetraethoxysilane) 0.5wt%; ethanol / water = 95 / 5 (v / v);

[0112] 2. Mix the pretreated carbon powder micro-etching solution and the activation solution in a solid-liquid ratio of 1:12; 3. Reflux at 75°C for 2.5 hours under argon protection; 4. Centrifuge and vacuum dry at 50°C for 8 hours to obtain the surface activated carbon powder micro-etching solution.

[0113] Step 3: In situ graft polymerization

[0114] Aniline monomer with a concentration of 0.3 mol / L was prepared and pre-cooled to 0°C for use; a surface activated carbon powder micro-etching solution was added and pre-oxidized at 2°C, and after stirring at 300 rpm for 40 minutes, ammonium persulfate with a concentration of 0.15 mol / L was slowly added dropwise to the aniline monomer at a rate of 1 mL / min, the temperature was raised to 18°C, and the reaction was carried out at 500 rpm for 120 minutes; then sodium dodecylbenzene sulfonate (SDBS) with a concentration of 0.08 mol / L was added, the pH value of the reaction was controlled to 1.3, the temperature was raised to 26°C again, and the reaction was carried out at 200 rpm for 150 minutes until the reaction was completed, NaOH solution was added to adjust the pH value of the system to 9.0 at a rate of 1.0 pH / min, and the product was collected by centrifugation after the reaction was completed to obtain a modified micro-etching solution, wherein the nano-scale coating layer on the surface of the carbon powder in the micro-etching solution was 50 nm, the porosity of the polyaniline coating layer was 15%, the average pore size was 3 nm, and the specific surface area was 50 m 2 / g;

[0115] Step 4: Post-processing and characterization

[0116] 1. The modified micro-etching solution was freeze-dried under vacuum freeze-drying conditions (-50°C, 10Pa, 24h), and then subjected to particle size analysis and electrochemical performance testing. The specific testing equipment and conditions are as follows:

[0117] 2. Particle size analysis: Mastersizer 3000 laser particle size analyzer;

[0118] 3. Electrochemical test: PARSTAT 4000 electrochemical workstation.

[0119] The specific experimental results after testing are shown in Table 2 below.

[0120] Table 2: Comparison of performance parameters of micro-etching fluid before and after modification

[0121]

[0122] It can be seen from Table 2 that the surface resistivity of the modified micro-etching solution is 1.7×10 8 Ω·m; the copper recovery rate of the modified micro-etching solution in the electrolytic copper extraction process was 90%, which was 12% higher than the copper recovery rate of 78% of the micro-etching solution before modification; the agglomeration index of the modified micro-etching solution was 1.10, and the Zeta potential (pH=1.5) of the modified micro-etching solution was -35mV, compared with -25mV of the micro-etching solution before modification. The larger the absolute value of the Zeta potential, the stronger the electrostatic repulsion between particles and the more stable the dispersion system.

[0123] Example 3

[0124] Experimental Materials:

[0125] Micro-etching liquid containing carbon powder: taken from the black hole process waste liquid of PCB factory, D 50 =0.25μm, specific surface area 85m 2 / g.

[0126] Chemical reagents:

[0127] Mixed acid system: concentrated sulfuric acid (98%) and concentrated nitric acid (65%) prepared in a volume ratio of 3:1; aniline monomer: Aladdin reagent, purity ≥99.5%, purified by vacuum distillation; SDBS (sodium dodecylbenzenesulfonate): Comeo Chemical, analytical grade.

[0128] Main equipment:

[0129] Ultrasonic processor: Sonics VCX750 (20-40 kHz adjustable); polymerization reactor: 500 mL jacketed glass reactor (with mechanical stirring); freeze dryer: Labconco FreeZone 4.5 L.

[0130] Process implementation steps

[0131] Step 1: Pre-treat the micro-etching solution containing carbon powder with acid

[0132] 1. Take 200g of micro-etching solution containing carbon powder and add it to mixed acid solution (H2SO4:HNO3=3:1 v / v), with a liquid-to-solid ratio of 8:1;

[0133] 2. Start ultrasonic treatment (40kHz, power density 150W / L) at 50℃ for 40 minutes to evenly mix the micro-etching solution containing carbon powder and the mixed acid solution;

[0134] 3. Treat with a polymerization reactor at 70°C for 20 minutes;

[0135] 4. Wash with deionized water after vacuum filtration until neutral. After the conductivity of the pre-treated carbon powder micro-etching solution is less than 5μS / cm, perform surface activation treatment.

[0136] Step 2: Surface activation

[0137] 1. Prepare activation solution: APTES (γ-aminopropyltriethoxysilane) 3.0 wt%; TEOS (tetraethoxysilane) 1.0 wt%; ethanol / water = 95 / 5 (v / v);

[0138] 2. Mix the pretreated carbon powder micro-etching solution and the activation solution in a solid-liquid ratio of 1:15; 3. Reflux at 85°C for 1.5 hours under argon protection; 4. Centrifuge and vacuum dry at 80°C for 4 hours to obtain the surface activated carbon powder micro-etching solution.

[0139] Step 3: In situ graft polymerization

[0140] Aniline monomer with a concentration of 0.8 mol / L was prepared and pre-cooled to 5°C for standby use; a surface activated carbon powder micro-etching solution was added and pre-oxidized at 5°C, and after reacting for 45 minutes under stirring at 300 rpm, ammonium persulfate with a concentration of 0.4 mol / L was slowly added dropwise to the aniline monomer at a rate of 1 mL / min, the temperature was raised to 20°C, and the reaction was carried out under stirring at 500 rpm for 120 minutes; then sodium dodecylbenzene sulfonate (SDBS) with a concentration of 0.15 mol / L was added, the pH value of the reaction was controlled to 1.7, the temperature was raised to 28°C again, and the reaction was carried out under stirring at 200 rpm for 100 minutes until the reaction was completed, NaOH solution was added to adjust the pH value of the system to 10.5 at a rate of 1.5 pH / min, and the product was collected by centrifugation after the reaction was completed to obtain a modified micro-etching solution, wherein the nano-scale coating layer on the surface of the carbon powder in the micro-etching solution was 100 nm, the porosity of the polyaniline coating layer was 30%, the average pore size was 10 nm, and the specific surface area was 80 m 2 / g;

[0141] Step 4: Post-processing and characterization

[0142] 1. The modified micro-etching solution was freeze-dried under vacuum freeze-drying conditions (-50°C, 10Pa, 24h), and then subjected to particle size analysis and electrochemical performance testing. The specific testing equipment and conditions are as follows:

[0143] 2. Particle size analysis: Mastersizer 3000 laser particle size analyzer;

[0144] 3. Electrochemical test: PARSTAT 4000 electrochemical workstation.

[0145] The specific experimental results after testing are shown in Table 3 below.

[0146] Table 3: Comparison of performance parameters of micro-etching fluid before and after modification

[0147]

[0148] It can be seen from Table 3 that the surface resistivity of the modified micro-etching solution is 1.9×10 8 Ω·m; the copper recovery rate of the modified micro-etching solution in the electrolytic copper extraction process was 93%, which was 15% higher than the copper recovery rate of 78% of the micro-etching solution before modification; the agglomeration index of the modified micro-etching solution was 1.10, and the Zeta potential (pH=1.5) of the modified micro-etching solution was -39mV, compared with -25mV of the micro-etching solution before modification. The larger the absolute value of the Zeta potential, the stronger the electrostatic repulsion between particles and the more stable the dispersion system.

[0149] Example 4 (Industrial Mass Production System)

[0150] (1) Equipment configuration and process control, core equipment list:

[0151] Continuous ultrasonic treatment system: processing capacity 500kg / h;

[0152] Titanium alloy tank: 40kHz dual-frequency ultrasonic wave, power density 80-120W / L;

[0153] Fluidized bed polymerization reactor: Hastelloy C276 material, Φ1200×3000mm, equipped with high-precision temperature control system (±0.2℃);

[0154] Intelligent centrifugal separation system, horizontal spiral centrifuge, G value 3000G, carbon powder recovery rate ≥ 99.5%;

[0155] Vacuum belt dryer: processing capacity 500kg / h, working vacuum degree ≤10Pa, microwave assisted heating (2450MHz, power adjustable).

[0156] (2) Key points of mass production process control

[0157] Table 4: Process parameter monitoring system

[0158]

[0159] (3) Deepen the comparative experimental data table:

[0160] Table 5: Temperature gradient scheme design (other parameters fixed)

[0161]

[0162] The process parameter monitoring system in Table 4 was used to modify the micro-etching solution containing carbon powder according to the temperature gradient scheme shown in Table 5 to prepare a modified micro-etching solution. The specific modified micro-etching solutions prepared are shown in Tables 6 and 7 below.

[0163] Table 6: Effect of temperature gradient on the coating properties of carbon powder in modified micro-etching solution

[0164]

[0165] As can be seen from Table 6, the experimental group A was subjected to a gradient temperature increase treatment according to the temperature range of the stage gradient. The coating thickness in group A was within the 50-100 nm level, the thickness deviation was small, and the surface resistivity, electrolytic mobility and combined strength of the modified micro-etching solution all met the requirements; the gradient temperature increase in the other three groups was not within the range of the stage gradient temperature increase, and the coating thickness, thickness deviation, electrolytic mobility and combined strength of the carbon powder in the modified micro-etching solution prepared therefrom could not meet the requirements.

[0166] Table 7: Relationship between temperature gradient and coating thickness

[0167]

[0168] In Table 7, Note: For the compression type D group, stage II is cancelled and the process goes directly from stage I to stage III.

[0169] As can be seen from Table 7, in the stepped three-stage heating group A, the thickness of the polyaniline coating on the surface of the carbon powder in the modified micro-etching solution is 85nm, and the crystallinity is 78.5%, which meets the requirements; in the high-temperature group B, the coating thickness is low and cannot meet the requirements; the temperature of the low-temperature group C is lower than the temperature of the three stages of group A, and its coating thickness meets the requirements, and its effect on the coating thickness is smaller than that of the high-temperature group B; the compression group D does not proceed to the second stage of chain growth and directly enters the third stage of cross-linking. Its coating thickness is thick and the crystallinity is high, which cannot meet the use requirements; the temperature is too high, the chain growth is faster, and the coating thickness is too thick, so it cannot meet the requirements.

[0170] Taking the temperature gradient of the optimal temperature gradient group A as the specific operating condition, 5 parallel experiments were carried out on the micro-etching solution containing carbon powder. The specific experimental results are shown in Table 8 below.

[0171] Table 8: Optimal temperature gradient verification experiment (n=5)

[0172]

[0173] It can be seen from Table 8 that within the optimal temperature gradient range, the thickness of the polyaniline coating on the surface of the carbon powder in the modified micro-etching solution, as well as the resistivity, mobility and copper recovery rate of the modified micro-etching solution all meet the requirements, and the values ​​of the five parallel experiments are basically consistent.

[0174] Through the above experiments, it was found that the stepped temperature control (Group A) achieved the best balance between thickness uniformity (±14.1%) and electrical properties; although the compression scheme (Group D) achieved the maximum thickness, the thickness deviation increased by 33.3% and the bonding strength decreased; for every 5°C increase in the temperature gradient, the polymerization rate increased by 120% but the crystallinity decreased by 8-12%; Stage II (15-20°C) plays a key role in the orderly arrangement of molecular chains, and its absence will lead to a disordered structure (Group D).

[0175] In summary, in order to ensure the quality of the modified micro-etching solution, the present invention implements the following quality assurance measures on the modified micro-etching solution:

[0176] 1. Take samples from each batch to test the integrity of the coating layer on the carbon powder surface in the modified micro-etching solution:

[0177] Observation: Accelerating voltage 5kV, observe more than 50 particles, coating thickness qualification standard: 50-100nm (±15% deviation allowed);

[0178] 2. Process abnormality warning mechanism: Automatic shutdown is triggered when impedance mutation is greater than 5%, and emergency cooling is activated when temperature fluctuation is greater than ±1°C;

[0179] 3. Product grading standards: AA grade: coating integrity ≥ 95%, resistivity ≥ 1×10 8 Ω·m; Grade A: coating integrity ≥90%, resistivity ≥5×10 7 Ω·m; Class B: coating integrity ≥85%, resistivity ≥1×10 7 Ω·m; Only modified micro-etching fluids that have passed quality assurance can be used.

[0180] Comparative Example:

[0181] The modified micro-etching solution prepared by the present invention is compared with the traditional silane-modified micro-etching solution process. The specific contents are shown in Tables 9 to 11 below.

[0182] Table 9: Comparison of modified micro-etching solution and traditional silane-modified micro-etching solution process

[0183]

[0184] It can be seen from Table 9 that the surface resistivity of the modified micro-etching solution is 1.8×10 8Ω·m compared to the surface resistivity of the micro-etching solution prepared by the traditional process of 2.5×10 5 The Ω·m value increased by 719 times. The copper purity of the modified micro-etching solution during electrolytic copper extraction was 99.2%, a 2.4% increase compared to the 96.8% copper purity of the micro-etching solution prepared by the traditional process. The anode maintenance cycle of the modified micro-etching solution was 1500 hours, a 650% increase compared to the 200-hour maintenance cycle of the modified micro-etching solution prepared by the traditional process. The electrolytic mobility of the modified micro-etching solution was 0.03 cm 2 / (V·s), compared with the micro-etching solution prepared by traditional process, the recycling rate is 0.51cm 2 / (V·s) decreased by 94%.

[0185] Table 10: Comparison of core performance of modified microetching fluids compared to conventional silane modification processes (laboratory scale)

[0186]

[0187] It can be seen from Table 10 that the surface resistivity of the modified micro-etching solution is 1.8×10 8 Ω·m compared with the surface resistivity of the modified micro-etching solution prepared by the traditional process of 2.5×10 5 Ω·m increased by 719 times; electrolytic mobility was 0.03cm 2 / (V·s) Compared with the 0.51cm of the modified micro-etching solution of the traditional process 2 / (V·s) increased by 94.1%; after electrolytic copper extraction of the modified micro-etching solution, copper recovery increased by 18.2%, carbon powder sedimentation rate increased by 82.2%, and anode polarization resistance increased by 646%; solution conductivity increased by 646%, and solution conductivity increased by 86.2%, all of which met the requirements.

[0188] Table 11: Process stability comparison (production data for 3 consecutive months)

[0189]

[0190] As can be seen from Table 11, the purity of electrolytic copper after the modified micro-etching solution is used for electrolytic copper extraction is increased by 6.2 times, the carbon powder concentration fluctuation is increased by 9.8 times, the anode voltage fluctuation is increased by 8 times, the current efficiency fluctuation is increased by 9.4 times, and the energy consumption fluctuation is increased by 8.6 times, all of which meet the requirements.

[0191] The modified micro-etching solution of the present invention and the modified micro-etching solution prepared by the traditional process were subjected to a dispersion stability test for 48 hours in an environment with a pH value of 1.0-2.0. The specific test results are shown in Table 12.

[0192] Table 12: Comparison of electrolytic mobility at different pH values

[0193]

[0194] In Table 12: In the pH range of 1.0-2.0, the mobility of the micro-etching solution modified by the present invention fluctuates within a range of ±0.005 within 48 hours, while the mobility of the micro-etching solution modified by the traditional process fluctuates within a range of ±0.15 within 48 hours, which is larger than the fluctuation range of the micro-etching solution modified by the present invention and is more unstable. Therefore, the dispersion stability of the micro-etching solution modified by the present invention in an environment with a pH value of 1.0-2.0 is greater than 48 hours.

[0195] In summary, the electrolysis efficiency of the modified micro-etching solution prepared by the method for treating carbon powder in the micro-etching solution of the circuit board industry provided by the present invention is improved, and the copper recovery rate of the electrolytic copper extraction treatment is increased from 78% to 92% (Cu 2+ 40g / L working conditions); the process stability of the modified micro-etching solution is enhanced, and the fluctuation of the carbon powder concentration therein is controlled within ±5%; the use of the modified micro-etching solution can extend the life of the equipment and extend its anode maintenance cycle from 200h to 1500h; the reuse rate of the modified micro-etching solution prepared by the present invention can be increased to 85%, which can significantly improve environmental benefits and is particularly suitable for solving the short circuit problem caused by the conductive migration of carbon powder in the copper extraction process.

[0196] The above descriptions are merely a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application discloses the preferred embodiments as above, they are not intended to limit the present application. Any technical personnel familiar with the present profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for treating carbon powder in micro-etching solution in the circuit board industry, characterized in that: The processing method comprises the following steps: Step S1: treating the micro-etching solution containing carbon powder with a mixed acid solution and ultrasonicating to obtain a pre-treated carbon powder micro-etching solution; Step S2: mixing the pre-treated carbon powder micro-etching solution with the activation solution under an inactive atmosphere, refluxing, centrifuging, and drying to obtain a surface-activated carbon powder micro-etching solution; Step S3: subjecting the surface activated carbon powder micro-etching solution to a mixture containing aniline monomer, ammonium persulfate, and dodecylbenzenesulfonic acid, respectively, to three-stage gradient polymerization to obtain a modified micro-etching solution; In step S3, the three-stage gradient polymerization includes a pre-oxidation stage, a chain growth stage, and a cross-linking stage; The temperature of the pre-oxidation stage is 0-5°C, and the time of the pre-oxidation stage is 30-45 minutes; The temperature of the chain extension stage is 15-20°C, and the time of the chain extension stage is 60-120 minutes; The temperature of the cross-linking stage is 25-28°C, and the time of the cross-linking stage is 100-150 minutes; After the cross-linking stage, NaOH solution is added to adjust the pH value of the reaction system to 9.0-10.5 at a rate of 0.5-1.5 pH / min.

2. The processing method according to claim 1, characterized in that In step S1, the liquid-to-solid ratio of the mixed acid solution to the carbon powder-containing micro-etching solution is 3:1 to 8:1; The mixed acid solution includes concentrated sulfuric acid and concentrated nitric acid, and the volume ratio of concentrated sulfuric acid to concentrated nitric acid is 3:1; The ultrasonic temperature is 50-70° C., the ultrasonic time is 20-40 min, and the ultrasonic power density is 80-150 W / L.

3. The processing method according to claim 1, characterized in that In step S2, the activation solution includes γ-aminopropyltriethoxysilane, tetraethoxysilane and ethanol; The mass percentage of γ-aminopropyltriethoxysilane in the activation solution is 2.0-3.0 wt.%; The mass percentage of tetraethoxysilane in the activation solution is 0.5-1.0 wt.%; The solid-to-liquid ratio of the pretreated carbon powder micro-etching solution to the activation solution is 1:10-1:

15.

4. The processing method according to claim 1, characterized in that In step S2, the inert atmosphere is selected from at least one of nitrogen, argon, and helium; The reflux temperature is 75-85° C., and the reflux time is 1.5-2.5 h; The drying temperature is 50-80° C., and the drying time is 4-8 hours.

5. The processing method according to claim 1, characterized in that In step S3, the concentration of the aniline monomer is 0.3-0.8 mol / L, and the concentration of the ammonium persulfate is 0.15-0.4 mol / L.

6. The processing method according to claim 1, characterized in that In step S3, the addition concentration of dodecylbenzenesulfonic acid is 0.08-0.15 mol / L; During the cross-linking stage, the pH value of the reaction system needs to be controlled to be 1.3-1.

7.

7. The modified micro-etching solution prepared by the treatment method according to any one of claims 1 to 6, characterized in that: The thickness of the polyaniline coating layer coated on the surface of the carbon powder in the modified micro-etching solution is 50-100 nm; The porosity of the polyaniline coating layer is 15-30%, the average pore size of the polyaniline coating layer is 3-10 nm, and the specific surface area of ​​the polyaniline coating layer is 50-80 m 2 / g.

8. The modified micro-etching solution according to claim 7, characterized in that: The surface resistivity of the modified micro-etching solution is ≥1×10 8 Ω·m, the Zeta potential of the modified micro-etching solution is -35mV~-40mV, and the electrolytic mobility of the modified micro-etching solution is less than 0.05cm 2 / (V·s).

9. The modified micro-etching solution according to claim 7, characterized in that: The modified micro-etching solution has a dispersion stability of more than 48 hours at a pH value of 1.0-2.0.

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