A method for controlling surface roughness of a rolled copper foil

Abstract

This invention relates to the field of metal surface treatment technology and discloses a method for controlling the surface roughness of rolled copper foil. The method includes: real-time monitoring and calculation of the time-first derivative of the redox potential of the working fluid; triggering synchronous pulsed injection of hydrogen peroxide and glycine solution when the derivative value negatively exceeds a set warning threshold; the injected glycine complexes with accumulated free copper ions, cutting off the catalytic decomposition path of hydrogen peroxide at its source and maintaining the stability of the working fluid; simultaneously, the forcibly cooled working fluid is vertically impacted on the moving copper foil surface at a set pressure, absorbing and releasing heat to lock the temperature of the micro-reaction zone; 2-mercaptobenzimidazole in the composition preferentially adsorbs at grain boundaries, generating steric hindrance and guiding isotropic surface dissolution. This invention stabilizes the micro-etching system and obtains rolled copper foil with low roughness and uniform surface through closed-loop feeding based on the first derivative of the potential, cold fluid impact temperature control, and additive grain boundary adsorption.

Description

Technical Field

[0001] This invention relates to the field of metal surface treatment technology, specifically to a method for controlling the surface roughness of rolled copper foil. Background Technology

[0002] Due to its excellent flexibility and conductivity, rolled copper foil is widely used in the manufacture of flexible printed circuit boards and high-frequency and high-speed printed circuit boards. In the production process of printed circuit boards, rolled copper foil usually needs to be micro-etched to remove the oxide layer on the surface and give it a specific microstructure, thereby ensuring the bonding strength of subsequent lamination or circuit fabrication processes.

[0003] Traditional micro-etching processes often use a mixture of hydrogen peroxide and acid as the working fluid. In actual continuous production, as the micro-etching reaction proceeds, free copper ions continuously accumulate within the working fluid. These accumulated free copper ions accelerate the decomposition of hydrogen peroxide, leading to a rapid decay of the effective components in the micro-etching solution. This instability of the chemical system causes the etching rate to fluctuate with production time, making it difficult to maintain a consistent surface treatment effect. Simultaneously, the crystal structure of rolled copper foil itself determines that its grain boundaries have high free energy. When traditional micro-etching solutions act on copper foil, they cause deep anisotropic corrosion along the grain boundary direction. This intergranular corrosion behavior creates microscopic pits on the copper foil surface, damaging surface smoothness and resulting in high and uneven overall surface roughness of the treated copper foil. For high-frequency, high-speed printed circuit boards, high and uneven copper foil surface roughness exacerbates the skin effect during high-frequency signal transmission, causing severe signal loss. Therefore, existing conventional micro-etching methods are insufficient to meet the process requirements of low surface roughness and high uniformity for high-frequency, high-speed applications. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for controlling the surface roughness of rolled copper foil, which solves the problems of instability of the micro-etching solution caused by the accelerated decomposition of hydrogen peroxide catalyzed by free copper ions in the existing micro-etching process, and the high surface roughness and poor uniformity of copper foil caused by anisotropic corrosion along grain boundaries.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for controlling the surface roughness of rolled copper foil includes the following steps: The initial rolled bare copper foil is fed into the degreasing section through a continuous conveying system for spray degreasing and water washing pretreatment to obtain pretreated rolled copper foil. The pretreated rolled copper foil is fed into a micro-etching main tank containing a working fluid, which is a multi-component synergistic micro-etching composition. The working fluid in the micro-etching main tank is extracted and introduced into an external heat exchanger to force cooling and stabilize to the first target temperature, thus obtaining the cooled working fluid. The cooled working fluid is pumped into an immersion fluid distributor installed below the liquid surface of the micro-etching main tank, and the upper and lower surfaces of the traveling rolled copper foil are vertically impacted with a set spray pressure, so that the temperature of the micro-reaction zone on the surface of the rolled copper foil is locked at the second target temperature. During the operation of the micro-etching main tank, an automated closed-loop control is initiated to introduce the working fluid into an external detection flow cell equipped with an ultrasonic transducer. The oxidation-reduction potential signal of the working fluid is continuously read as an effective instantaneous value, and the time first derivative of the filtered oxidation-reduction potential value is calculated in real time. When the calculated first time derivative exceeds the set system warning threshold, the metering pump is triggered to synchronously pulse-inject hydrogen peroxide replenishment solution and glycine solution into the micro-etching main tank until the first time derivative returns to the stable baseline. After leaving the micro-etching tank, the rolled copper foil enters the water washing section for cleaning. After removing moisture and baking, the finished rolled copper foil is obtained.

[0006] By adopting the above technical solution, rolled copper foil can obtain an extremely stable etching environment in the micro-etching main tank, thereby achieving uniform control of surface roughness. The reason why this effect can be achieved is closely related to the physical flow field and closed-loop feeding mechanism constructed by this invention.

[0007] In terms of flow field and temperature control, the working fluid after forced cooling is vertically impacted onto the surface of the moving copper foil by an externally set pressure. With the physical impact of the fluid, the working fluid spreads at the liquid-solid interface of the copper foil and establishes a uniform high-viscosity Nernst diffusion layer. Since the injected fluid is cooling fluid, this cold fluid targeted impact can absorb and directly neutralize the large amount of heat released by the micro-etching reaction itself in a timely manner. In this way, the temperature of the micro-reaction zone is forcibly locked near the second target temperature in the macroscopic room temperature bath, preventing the etching rate runaway phenomenon caused by local overheating of the interface.

[0008] At the level of dynamic equilibrium of chemical composition, the basic reaction of the micro-etching process is the interaction of elemental copper with hydrogen peroxide and hydrogen ions, which in turn generates free copper ions and water. As the etching reaction continues, the concentration of free copper ions in the main micro-etching tank continues to rise. These free copper ions, in turn, act as catalysts, causing the hydrogen peroxide in the working fluid to decompose ineffectively into water and oxygen. The large-scale ineffective decomposition of hydrogen peroxide will cause the redox potential of the working fluid to drop rapidly. To curb this vicious cycle, this invention abandons the traditional timed and quantitative replenishment mode and instead monitors the first derivative of the oxidation-reduction potential over time in real time. When the first derivative over time is detected to exceed the warning threshold in a negative direction, it directly indicates that the catalytic decomposition of hydrogen peroxide has entered the acceleration stage. At this critical point, the metering pump is triggered to simultaneously inject hydrogen peroxide replenishment solution and glycine solution in a pulsed manner. The injected glycine molecules can quickly capture free copper ions in the tank solution, and the two combine to form glycine copper complex ions and release hydrogen ions. This coordination process consumes a large amount of catalytically active free copper ions, cutting off the catalytic decomposition pathway of hydrogen peroxide at its source. As the free copper ions are complexed with glycine, the hydrogen peroxide concentration is replenished and stabilized, and the time first derivative of the redox potential of the working solution gradually returns to a stable baseline state, thereby maintaining the kinetic constant of the entire etching microenvironment within a constant range.

[0009] Preferably, the preparation method of the multi-component synergistic micro-etching composition includes the following steps: Add 900 to 1100 parts by weight of deionized water to the mixing tank, and add 100 to 120 parts by weight of concentrated sulfuric acid dropwise while stirring, controlling the system temperature within the range of 29 to 36°C; add 2.0 to 4.0 parts by weight of polyethylene glycol and 10 to 20 parts by weight of glycine sequentially, and stir within the temperature range of 29 to 36°C until the solid is completely dissolved; in a separate auxiliary tank, add 0.05 to 0.1 parts by weight of 2-mercaptobenzimidazole to 5.0 to 8.0 parts by weight of ethylene glycol monobutyl ether, and stir in a sealed container within the temperature range of 24 to 31°C until completely dissolved to form a homogeneous transparent solution, and then pour the mixture into the mixing tank; Add 0.025 to 0.05 parts by weight of sodium chloride to the mixing vessel and stir; then cool to 21 to 26°C, add 35 to 50 parts by weight of hydrogen peroxide and stir to obtain the multi-component synergistic micro-etching composition; the rate of adding concentrated sulfuric acid is 15 to 25 parts / min, and the rate of adding hydrogen peroxide is 8 to 12 parts / min; the rate of adding 2-mercaptobenzimidazole to ethylene glycol monobutyl ether is 0.01 to 0.02 parts / min, and the stirring time is 10 to 15 minutes.

[0010] By adopting the above technical solution, the conventional direct addition of solid additives will result in local uneven concentration. The present invention promotes the formation of a homogeneous transparent solution by combining 2-mercaptobenzimidazole with ethylene glycol monobutyl ether before mixing it into the micro-etching main tank through the auxiliary tank solution preparation method. When the micro-etching composition acts on the copper foil surface, 2-mercaptobenzimidazole molecules can penetrate the Nernst diffusion layer on the copper foil surface and preferentially coordinate and adsorb in the copper foil grain boundaries and microcrack areas in the high free energy state. The adsorbed 2-mercaptobenzimidazole molecules build a significant steric barrier at the grain boundaries, preventing hydrogen ions and hydrogen peroxide from continuing to penetrate into the deeper grain boundaries, thereby forcibly guiding the etching path of the rolled copper foil from anisotropic intergranular corrosion that will produce deep pits to a gradual isotropic surface dissolution direction. Meanwhile, the nonpolar hydrocarbon chains of ethylene glycol monobutyl ether molecules generate intermolecular binding forces with the polyethylene glycol molecular skeleton in the solution preparation vessel, while the hydrophilic groups of ethylene glycol monobutyl ether establish a hydrogen bond network with polar water molecules. This network interaction structure between macromolecules and solvents counteracts the dehydration and coagulation phenomenon caused by the large accumulation of free copper ions in the micro-etching working solution, ensuring that the actual operating temperature of the working solution remains below the thermodynamic cloud point of the free copper ion enrichment state during long-term operation, and avoiding abnormal precipitation of organic additives.

[0011] Preferably, in the preparation method of the multi-component synergistic micro-etching composition, the stirring speed is set to 150 to 180 rpm; and the rate of injecting the mixture into the mixing vessel is 1.5 to 2.5 parts / min.

[0012] By adopting the above technical solution, setting the stirring speed within a specific range and the injection rate of the mixed liquid at a relatively slow speed, sufficient time buffer is provided for the diffusion of organic molecules in strong acid and strong oxidizing environments, preventing local material agglomeration or even degradation caused by instantaneous contact with high-concentration raw materials.

[0013] Preferably, the specific process for pretreatment by spray degreasing and water washing includes: feeding a rolled bare copper foil with an initial surface roughness of 1.5 to 2.0 μm into the degreasing section at a linear speed of 8 to 12 m / min, spraying it with a sodium hydroxide aqueous solution with a mass fraction of 4% to 6% at a temperature of 38 to 42°C for 15 to 30 seconds, followed by spray washing with deionized water at a pressure of 0.2 to 0.3 MPa, and draining the free water on the surface.

[0014] By adopting the above technical solution, a sodium hydroxide solution of appropriate concentration and temperature, combined with subsequent pressure deionized water rinsing, removes the anti-rust coating and residual rolling oil from the surface of the initial rolled copper foil. This pretreatment process provides a uniform initial wetting substrate for the subsequent micro-etching solution to adhere, avoiding the problem of etching blind spots caused by local organic residues.

[0015] Preferably, during the process of extracting and cooling the working fluid and pumping it into the submersible fluid distributor for vertical impact, the control parameters of the physical flow field and temperature of the working fluid are as follows: the working fluid is extracted by a centrifugal pump at a flow rate of 300 to 500 L / min and introduced into an external titanium plate heat exchanger. The first target temperature is 26 to 28°C; the distance between the nozzle of the distributor and the surface of the rolled copper foil is 30 to 50 mm, and the spray pressure is 0.15 to 0.25 MPa; the total processing time of the rolled copper foil in the micro-etching main tank is 45 to 60 seconds; the second target temperature is 28 to 32°C.

[0016] By adopting the above technical solution, the cooling capacity of the external heat exchanger and the jet kinetic energy of the immersion distributor form a mutually supportive flow field control mechanism. After the working fluid is pre-cooled to the first target temperature, it impacts the copper foil surface with a set pressure jet. During this process, the working fluid absorbs the interface temperature rise caused by the etching reaction, which ultimately makes the actual copper foil surface temperature that is reacting constant within the second target temperature range, preventing the etching reaction kinetic parameters from drifting due to heat accumulation.

[0017] Preferably, the specific process of starting automated closed-loop control for signal reading and calculation includes: introducing the working fluid in the micro-etching main tank into an external detection flow cell at a flow rate of 2 to 5 L / min via a bypass circulation pump; an online probe for redox potential of a platinum electrode is installed in the flow cell; an ultrasonic transducer with an operating frequency of 40 kHz inside the flow cell is activated to perform ultrasonic oscillation for 10 to 15 seconds every 5 minutes; a programmable logic controller continuously reads the signal at a sampling frequency of 1 to 2 Hz, and uses an embedded moving average filtering algorithm to take the average value of the redox potential signal for 10 to 15 consecutive seconds as the effective instantaneous value, and calculates the first derivative of time.

[0018] By adopting the above technical solution, in order to prevent the detection electrode from becoming passivated due to long-term immersion, the ultrasonic transducer installed inside the flow cell will periodically turn on to vibrate, forcibly peeling off the microbubbles and chemical passivation film attached to the surface of the platinum probe, thereby ensuring that the redox potential signal collected by the probe truly reflects the current state of the working fluid. Meanwhile, considering the physical pulse interference brought about by the fluid flow itself, a moving average filtering algorithm is introduced to smooth the acquired raw potential signal, thus eliminating electronic and fluid noise interference for the subsequent calculation of the first time derivative.

[0019] Preferably, during the process of triggering the metering pump to synchronously pulse-inject hydrogen peroxide replenishment solution and glycine solution into the micro-etching main tank: the set system warning threshold is -5mV / min to -8mV / min; when the metering pump is triggered, the molar ratio of hydrogen peroxide to glycine injected in the pulse is controlled to be constant in the range of 3:1 to 4:1; the stable baseline is when the first derivative of time recovers to 0mV / min.

[0020] By adopting the above technical solution, once the warning threshold is exceeded and the material replenishment action is triggered, strictly locking the injection molar ratio of hydrogen peroxide and glycine can ensure that while replenishing the consumed oxidant, just enough glycine molecules are provided to complex the excess free copper ions. This linkage compensation mechanism avoids the complete collapse of the internal chemical balance of the working fluid due to the blind replenishment of a single component.

[0021] Preferably, the specific process of the rolled copper foil entering the water washing section for cleaning and subsequent dehydration and baking after leaving the micro-etching main tank includes: cleaning with countercurrent deionized water at 0.2 to 0.3 MPa for 15 to 20 seconds, removing surface moisture by squeezing with pressure rollers, and then sending it into a hot air circulating oven for baking at a temperature of 80 to 100°C for 10 to 20 seconds.

[0022] By adopting the above technical solution, the rolled copper foil that has completed micro-etching is immediately rinsed by countercurrent deionized water, the residual working solution is quickly diluted and peeled off, and the etching reaction is forcibly stopped; then, with the physical squeezing of water by pressure rollers and hot air baking, the secondary blackening or oxidation defects on the copper foil surface caused by the concentration of residual micro-etching solution during the water evaporation process are eliminated.

[0023] This invention provides a method for controlling the surface roughness of rolled copper foil. It has the following beneficial effects: 1. This invention establishes a diffusion layer at the liquid-solid interface by vertically impacting the surface of a rolled copper foil with a set pressure using a cooled working fluid. This cold fluid physical impact can directly neutralize the heat continuously generated by the micro-etching reaction, locking the temperature of the micro-reaction zone on the copper foil surface within the target range. This physical control method avoids sudden changes in the etching rate caused by local heat accumulation, ensuring the uniformity of the roughness distribution on the copper foil surface during continuous processing.

[0024] 2. This invention uses the first derivative of the redox potential over time as the trigger index for closed-loop feeding. When the critical point of accelerated decomposition of hydrogen peroxide is detected, hydrogen peroxide and glycine solution are injected simultaneously. The injected glycine coordinates with the free copper ions accumulated in the system, consuming the catalyst that causes ineffective decomposition of hydrogen peroxide and cutting off the autocatalytic decomposition path. This mechanism inhibits the rapid decay of the effective components of the working solution and maintains the long-term stability of the chemical kinetics of the micro-etching system.

[0025] 3. In this invention, 2-mercaptobenzimidazole is introduced into the micro-etching composition through a pre-dissolving process in an auxiliary tank. When its molecules come into contact with copper foil, they preferentially undergo coordination adsorption in the high free energy grain boundary region, forming steric hindrance. This steric hindrance effect hinders the continuous penetration of the micro-etching solution into the depth of the grain boundary, forcing the anisotropic intergranular corrosion that would originally develop into depth to be transformed into isotropic dissolution that develops laterally along the surface, thereby reducing the overall microscopic surface roughness of the rolled copper foil. Attached Figure Description

[0026] Figure 1 This is a schematic diagram showing the change of the physical properties of the working fluid of the present invention with the concentration of free copper ions. In this diagram, a is a schematic diagram showing the test results of the thermodynamic cloud point changing with the concentration of free copper ions, and b is a schematic diagram showing the test results of the dynamic viscosity changing with the concentration of free copper ions. Figure 2 This is a schematic diagram of the electrochemical performance of the working fluid of the present invention, wherein a is a schematic diagram of the AC impedance spectroscopy test results and b is a schematic diagram of the potentiodynamic polarization curve test results; Figure 3 This is a schematic diagram of the dynamic stability of the working fluid under area disturbance triggering of the present invention. In this diagram, a is a schematic diagram of the test results of the instantaneous concentration of free copper ions changing with the test time, and b is a schematic diagram of the test results of the actual relative concentration of remaining hydrogen peroxide changing with the test time. Figure 4 This is a schematic diagram of the surface roughness of the rolled copper foil after the processing of the present invention, wherein a is a schematic diagram of the spatial distribution test results of the arithmetic mean roughness, and b is a schematic diagram of the ten-point height test results of the micro-unevenness. Figure 5 This is a schematic diagram of the MIT folding resistance of the rolled copper foil after the present invention. In this diagram, a is a schematic diagram of the test results of the number of folding resistance in the belt direction of the rolled copper foil machine, and b is a schematic diagram of the test results comparing the average number of folding resistance in the belt direction and the transverse direction of the rolled copper foil machine. Figure 6 This is a schematic diagram of the peel strength of the rolled copper foil of the present invention, wherein a is a schematic diagram of the average peel strength test results under different aging conditions, and b is a schematic diagram of the test results of the instantaneous peel line load changing with peel displacement. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. The embodiments described below are only intended to illustrate the implementation of the present invention, and the scope of protection of the present invention is not limited to the specific embodiments, but is defined by the claims. Any modifications and substitutions made by those skilled in the art without departing from the spirit and scope of the present invention shall be deemed to fall within the scope of protection of the present invention.

[0028] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0029] Polyethylene glycol is a water-soluble, nonionic homopolymer polymer formed by the condensation polymerization of ethylene oxide and water, with hydroxyl groups at both ends of the chain segments; in this embodiment of the invention, a model with a weight-average molecular weight of 8000 is specifically used; it is a white flake or powder solid at room temperature, and its aqueous solution will undergo phase separation and show a turbidity point under certain temperature and salt concentration; the CAS number is 25322-68-3.

[0030] 2-Mercaptobenzimidazole is a small molecule thiol compound containing a heterocyclic structure. Its molecular structure contains a benzene ring, an imidazole heterocycle, and a free thiol group attached to the imidazole heterocycle. At room temperature, it is a white to off-white crystalline powder. It has extremely low solubility in pure water, belonging to slightly soluble or even sparingly soluble substances, but is soluble in some polar organic solvents. Its CAS number is 583-39-1.

[0031] Ethylene glycol monobutyl ether is a small molecule compound of aliphatic glycol ethers. Its molecular structure exhibits typical amphiphilic characteristics, with a hydrophilic ether bond and alcohol hydroxyl group at one end and a hydrophobic straight-chain butyl group at the other end. It is a colorless and transparent liquid at room temperature and has excellent solubility, being completely miscible with water and a variety of polar and nonpolar organic solvents. Its CAS number is 111-76-2.

[0032] Glycine is an aliphatic amino acid whose molecule contains both a basic primary amino group and an acidic carboxyl group. It appears as a white crystalline powder at room temperature and is soluble in water. In aqueous solutions with a specific pH value, it can undergo bidentate chelation coordination reactions with heavy metal ions through the lone pair electrons of nitrogen and oxygen atoms. Its CAS number is 56-40-6.

[0033] In this embodiment, the unit of measurement for the amount of each material and solvent is uniformly referred to as parts by weight.

[0034] Preparation Example 1: This preparation example provides a method for preparing a multi-component synergistic micro-etching composition, comprising the following steps: First, inject 1000 parts of deionized water into the main mixing vessel equipped with a jacketed cooling system and mechanical stirring. Turn on the mechanical stirring and set the speed to 150 rpm. Add 100 parts of concentrated sulfuric acid dropwise at a rate of 20 parts / min. At the same time, turn on the jacket cooling water to control the system temperature between 29 and 31°C. Stir at 150 rpm for 5 minutes within this temperature range. Then, 2.0 parts of polyethylene glycol and 10 parts of glycine were added sequentially to the main mixing tank, and stirred at 150 rpm for 20 minutes within a temperature range of 29 to 31°C until the solid was completely dissolved. Next, in a separate auxiliary tank, 0.05 parts of 2-mercaptobenzimidazole were added to 5.0 parts of ethylene glycol monobutyl ether at a rate of 0.01 parts / min. The auxiliary tank was sealed and stirred at 200 rpm for 10 minutes within a temperature range of 24 to 26°C to completely dissolve the 2-mercaptobenzimidazole into a homogeneous transparent solution. The mixture was then injected into the main mixing tank at a rate of 2 parts / min. Then, 0.025 parts of sodium chloride were added to the main mixing vessel and stirred at 150 rpm for 5 minutes. Finally, the refrigerant flow rate was adjusted to lower the temperature inside the main mixing vessel to 21 to 23°C, and 35 parts of hydrogen peroxide were added at a rate of 10 parts / min. After the addition was completed, the mixture was stirred at 150 rpm for 10 minutes to obtain the multi-component synergistic micro-etching composition, which is referred to here as composition A.

[0035] Preparation Example 2: This preparation example provides a method for preparing a multi-component synergistic micro-etching composition, comprising the following steps: First, inject 1000 parts of deionized water into the main mixing vessel equipped with a jacketed cooling system and mechanical stirring. Turn on the mechanical stirring and set the speed to 160 rpm. Add 110 parts of concentrated sulfuric acid dropwise at a rate of 20 parts / min. At the same time, turn on the jacket cooling water to control the system temperature at 31 to 33°C. Stir at 160 rpm for 5 minutes within this temperature range. Then, 3.0 parts of polyethylene glycol and 15 parts of glycine were added sequentially to the main mixing tank, and stirred at 160 rpm for 25 minutes within a temperature range of 31 to 33°C until the solid was completely dissolved. Next, in a separate auxiliary tank, 0.08 parts of 2-mercaptobenzimidazole were added to 6.5 parts of ethylene glycol monobutyl ether at a rate of 0.02 parts / min. The auxiliary tank was sealed and stirred at 200 rpm for 12 minutes within a temperature range of 27 to 29°C to completely dissolve the 2-mercaptobenzimidazole into a homogeneous transparent solution. The mixture was then injected into the main mixing tank at a rate of 2 parts / min. Then, 0.035 parts of sodium chloride were added to the main mixing vessel and stirred at 160 rpm for 5 minutes. Finally, the refrigerant flow rate was adjusted to lower the temperature inside the main mixing vessel to 23 to 25°C, and 42 parts of hydrogen peroxide were added at a rate of 10 parts / min. After the addition was completed, the mixture was stirred at 160 rpm for 10 minutes to obtain the multi-component synergistic micro-etching composition, which is referred to here as composition B.

[0036] Preparation Example 3: This preparation example provides a method for preparing a multi-component synergistic micro-etching composition, comprising the following steps: First, inject 1000 parts of deionized water into the main mixing vessel equipped with a jacketed cooling system and mechanical stirring. Turn on the mechanical stirring and set the speed to 180 rpm. Add 120 parts of concentrated sulfuric acid dropwise at a rate of 20 parts / min. At the same time, turn on the jacket cooling water to control the system temperature at 34 to 36°C. Stir at 180 rpm for 5 minutes within this temperature range. Then, 4.0 parts of polyethylene glycol and 20 parts of glycine were added sequentially to the main mixing tank, and stirred at 180 rpm for 30 minutes within a temperature range of 34 to 36°C until the solid was completely dissolved. Next, in a separate auxiliary tank, 0.1 parts of 2-mercaptobenzimidazole were added to 8.0 parts of ethylene glycol monobutyl ether at a rate of 0.02 parts / min. The auxiliary tank was sealed and stirred at 200 rpm for 15 minutes within a temperature range of 29 to 31°C to completely dissolve the 2-mercaptobenzimidazole into a homogeneous transparent solution. The mixture was then injected into the main mixing tank at a rate of 2 parts / min. Then, 0.05 parts of sodium chloride were added to the main mixing vessel and stirred at 180 rpm for 5 minutes. Finally, the refrigerant flow rate was adjusted to lower the temperature inside the main mixing vessel to 24 to 26°C, and 50 parts of hydrogen peroxide were added at a rate of 10 parts / min. After the addition was completed, the mixture was stirred at 180 rpm for 10 minutes to obtain the multi-component synergistic micro-etching composition, which is referred to here as composition C. Example

[0037] This embodiment provides a surface treatment method for rolled copper foil, including the following steps: S1. The rolled bare copper foil with an initial surface roughness of 1.5 μm is fed into the degreasing section through a horizontal continuous conveying system at a linear speed of 8 m / min. It is sprayed with a sodium hydroxide aqueous solution with a mass fraction of 4% at a temperature of 38°C for 15 seconds. Then, it is sprayed with deionized water at a pressure of 0.2 MPa and drained to obtain the pretreated rolled copper foil. S2. The pretreated rolled copper foil is fed into the micro-etching main tank. The composition A obtained in Preparation Example 1 is added to the micro-etching main tank as the working solution. The working solution in the micro-etching main tank is extracted by an acid-resistant centrifugal pump at a flow rate of 300 L / min and introduced into an external titanium plate heat exchanger. The temperature of the working solution is forcibly cooled and stabilized at 26°C by adjusting the flow rate of chilled water in the heat exchanger. S3. The cooled working fluid is directly pumped into the immersion fluid distributor installed below the liquid surface of the micro-etching main tank. The nozzle of the distributor is 30mm away from the surface of the rolled copper foil. The working fluid impacts the upper and lower surfaces of the moving rolled copper foil vertically with a jet pressure of 0.15MPa. The linear speed of the conveyor belt is controlled so that the total processing time of the rolled copper foil in the micro-etching main tank is 45 seconds. Because the reaction interface is targeted and impacted by the cold fluid, the temperature of the micro-reaction zone is locked at 28℃. S4. During the continuous operation of the micro-etching main tank, the automated closed-loop control is activated. The working fluid in the micro-etching main tank is introduced into the external detection flow cell at a flow rate of 2L / min through the bypass circulation pump. The flow cell is equipped with a platinum electrode oxidation-reduction potential online probe. An ultrasonic transducer with a working frequency of 40kHz is installed inside the flow cell. The control program is set to activate ultrasonic oscillation for 10 seconds every 5 minutes. The programmable logic controller system continuously reads the oxidation-reduction potential signal at a sampling frequency of 1Hz. The system program has an embedded moving average filtering algorithm, which takes the average value of the oxidation-reduction potential signal for 10 consecutive seconds as the effective instantaneous value, and calculates the time first derivative of the filtered oxidation-reduction potential value in real time. S5. Set the system warning threshold to -5mV / min. When the calculated first derivative of time crosses the warning threshold in a negative direction, the programmable logic controller immediately outputs a signal to trigger the dual-head proportional metering pump to synchronously and pulse-inject high-concentration hydrogen peroxide replenishment solution and glycine solution into the micro-etching main tank. Control the molar ratio of injected hydrogen peroxide to glycine to remain constant at 3:1 until the first derivative of time returns to the stable baseline of 0mV / min. S6. The rolled copper foil that leaves the micro-etching main tank immediately enters the water washing section and is washed with countercurrent deionized water at 0.2MPa for 15 seconds. After the surface moisture is removed by the pressure rollers, it is sent to the hot air circulating oven and baked at 80℃ for 10 seconds to obtain the finished rolled copper foil with surface treatment. Example

[0038] This embodiment provides a surface treatment method for rolled copper foil, including the following steps: S1. The rolled bare copper foil with an initial surface roughness of 1.8 μm is fed into the degreasing section through a horizontal continuous conveying system at a linear speed of 10 m / min. It is sprayed with a 5% sodium hydroxide aqueous solution at 40°C for 22 seconds, and then sprayed with deionized water at a pressure of 0.25 MPa. The surface free water is drained to obtain the pretreated rolled copper foil. S2. The pretreated rolled copper foil is fed into the micro-etching main tank. The composition B obtained in Preparation Example 2 is added to the micro-etching main tank as the working solution. The working solution in the micro-etching main tank is extracted by an acid-resistant centrifugal pump at a flow rate of 400 L / min and introduced into an external titanium plate heat exchanger. The temperature of the working solution is forcibly cooled and stabilized at 27°C by adjusting the flow rate of chilled water in the heat exchanger. S3. The cooled working fluid is directly pumped into the immersion fluid distributor installed below the liquid surface of the micro-etching main tank. The nozzle of the distributor is 40mm away from the surface of the rolled copper foil. The working fluid impacts the upper and lower surfaces of the moving rolled copper foil vertically with a jet pressure of 0.2MPa. The linear speed of the conveyor belt is controlled so that the total processing time of the rolled copper foil in the micro-etching main tank is 52 seconds. Because the reaction interface is targeted and impacted by the cold fluid, the temperature of the micro-reaction zone is locked at 30℃. S4. During the continuous operation of the micro-etching main tank, the automated closed-loop control is activated. The working fluid in the micro-etching main tank is introduced into the external detection flow cell at a flow rate of 3.5L / min through the bypass circulation pump. A platinum electrode oxidation-reduction potential online probe is installed in the flow cell. An ultrasonic transducer with a working frequency of 40kHz is installed inside the flow cell. The control program is set to activate ultrasonic oscillation for 12 seconds every 5 minutes. The programmable logic controller system continuously reads the oxidation-reduction potential signal at a sampling frequency of 1Hz. The system program has an embedded moving average filtering algorithm, which takes the average value of the oxidation-reduction potential signal for 12 consecutive seconds as the effective instantaneous value, and calculates the time first derivative of the filtered oxidation-reduction potential value in real time. S5. Set the system warning threshold to -6.5mV / min. When the calculated first derivative of time crosses the warning threshold in a negative direction, the programmable logic controller immediately outputs a signal to trigger the dual-head proportional metering pump to synchronously and pulse-inject high-concentration hydrogen peroxide replenishment solution and glycine solution into the micro-etching main tank. Control the molar ratio of injected hydrogen peroxide to glycine to remain constant at 3.5:1 until the first derivative of time returns to the stable baseline of 0mV / min. S6. The rolled copper foil that leaves the micro-etching main tank immediately enters the water washing section and is washed with countercurrent deionized water at 0.25MPa for 18 seconds. After the surface moisture is removed by the pressure rollers, it is sent to the hot air circulating oven and baked at 90℃ for 15 seconds to obtain the finished rolled copper foil with surface treatment. Example

[0039] This embodiment provides a surface treatment method for rolled copper foil, including the following steps: S1. The rolled bare copper foil with an initial surface roughness of 2.0 μm is fed into the degreasing section through a horizontal continuous conveying system at a linear speed of 12 m / min. It is sprayed with a 6% sodium hydroxide aqueous solution at 42°C for 30 seconds, and then sprayed with deionized water at a pressure of 0.3 MPa. The surface free water is drained to obtain the pretreated rolled copper foil. S2. The pretreated rolled copper foil is fed into the micro-etching main tank. The composition C obtained in Preparation Example 3 is added to the micro-etching main tank as the working solution. The working solution in the micro-etching main tank is extracted by an acid-resistant centrifugal pump at a flow rate of 500 L / min and introduced into an external titanium plate heat exchanger. The temperature of the working solution is forcibly cooled and stabilized at 28°C by adjusting the flow rate of chilled water in the heat exchanger. S3. The cooled working fluid is directly pumped into the immersion fluid distributor installed below the liquid surface of the micro-etching main tank. The nozzle of the distributor is 50mm away from the surface of the rolled copper foil. The working fluid impacts the upper and lower surfaces of the moving rolled copper foil vertically with a jet pressure of 0.25MPa. The linear speed of the conveyor belt is controlled so that the total processing time of the rolled copper foil in the micro-etching main tank is 60 seconds. Because the reaction interface is targeted and impacted by the cold fluid, the temperature of the micro-reaction zone is locked at 32℃. S4. During the continuous operation of the micro-etching main tank, the automated closed-loop control is activated. The working fluid in the micro-etching main tank is introduced into the external detection flow cell at a flow rate of 5L / min through the bypass circulation pump. The flow cell is equipped with a platinum electrode oxidation-reduction potential online probe. An ultrasonic transducer with a working frequency of 40kHz is installed inside the flow cell. The control program is set to activate ultrasonic oscillation for 15 seconds every 5 minutes. The programmable logic controller system continuously reads the oxidation-reduction potential signal at a sampling frequency of 1Hz. The system program has an embedded moving average filtering algorithm, which takes the average value of the oxidation-reduction potential signal for 15 consecutive seconds as the effective instantaneous value, and calculates the time first derivative of the filtered oxidation-reduction potential value in real time. S5. Set the system warning threshold to -8mV / min. When the calculated first derivative of time crosses the warning threshold in a negative direction, the programmable logic controller immediately outputs a signal to trigger the dual-head proportional metering pump to synchronously and pulse-inject high-concentration hydrogen peroxide replenishment solution and glycine solution into the micro-etching main tank. Control the molar ratio of injected hydrogen peroxide to glycine to remain constant at 4:1 until the first derivative of time returns to the stable baseline of 0mV / min. S6. The rolled copper foil that leaves the micro-etching main tank immediately enters the water washing section and is washed with countercurrent deionized water at 0.3MPa for 20 seconds. After the surface moisture is removed by the pressure rollers, it is sent to the hot air circulating oven and baked at 100℃ for 20 seconds to obtain the finished rolled copper foil with surface treatment.

[0040] Comparative Example 1: Compared with Example 2, the difference is that the working fluid in step S2 is replaced with a traditional micro-etching base fluid, which contains only 1000 parts of deionized water, 110 parts of concentrated sulfuric acid, 42 parts of hydrogen peroxide and 0.035 parts of sodium chloride. Polyethylene glycol, glycine, 2-mercaptobenzimidazole and ethylene glycol monobutyl ether are not added. At the same time, the automated closed-loop control system and pulse injection program in steps S4 and S5 are turned off. All other aspects are the same.

[0041] Comparative Example 2: Compared with Example 2, the difference is that when preparing the working solution, ethylene glycol monobutyl ether is not added, and 2-mercaptobenzimidazole powder is directly added to the main mixing vessel and mixed with polyethylene glycol. All other aspects are the same.

[0042] Comparative Example 3: Compared with Example 2, the difference is that 2-mercaptobenzimidazole is not added when preparing the working solution, but all other aspects are the same.

[0043] Comparative Example 4: Compared with Example 2, the difference is that the external titanium plate heat exchanger forced cooling and the submerged fluid distributor impact system in steps S2 and S3 are turned off, and natural cooling is achieved solely by the external jacket of the micro-etched main tank. The working fluid flows naturally into the main tank liquid surface in a pressureless state through conventional pipelines. All other aspects are the same.

[0044] Comparative Example 5: Compared with Example 2, the difference is that the external detection flow cell, ultrasonic cleaning, and dynamic closed-loop control triggered by the first derivative of oxidation-reduction potential time in steps S4 and S5 are cancelled. Instead, a fixed amount of hydrogen peroxide and glycine are replenished every 30 minutes according to the system running time. All other aspects are the same.

[0045] Comparative Example 6: Compared with Example 2, the difference is that glycine is not added when preparing the working solution, and when the metering pump is triggered in step S5, only high-concentration hydrogen peroxide replenishment solution is pulsedly injected into the micro-etching main tank, without injecting glycine solution, and the rest are the same.

[0046] Test Example 1: Compositions A, B, and C prepared in Examples 1, 2, and 3 were used as experimental groups; working solutions prepared according to the pure inorganic acid system without organic additives in Comparative Example 1 and Comparative Example 2 containing polyethylene glycol but without ethylene glycol monobutyl ether were used as control groups; 1000 mL of each working solution was measured and placed in a jacketed glass reactor equipped with mechanical stirring.

[0047] Analytical grade copper sulfate pentahydrate powder was added to each group of glass reactors in batches to construct four gradient test points with free copper ion mass concentrations of 0 g / L, 24.6 g / L, 51.8 g / L, and 75.2 g / L. After each addition, the mixture was stirred at a constant temperature of 30°C for 30 minutes.

[0048] After reaching the set copper ion concentration nodes, 100 mL of test solution was extracted and transferred into the sample cell of the transmittance turbidity point analyzer. The sample cell was linearly heated at a heating rate of 1 °C / min. The system temperature was recorded when the transmittance of the detection light at a wavelength of 600 nm suddenly dropped to 50% of the initial value. The recorded temperature was recorded as the thermodynamic turbidity point of the test solution at the corresponding copper ion concentration. The pure inorganic acid system did not show phase separation characteristics and was recorded as having no turbidity point.

[0049] After completing the cloud point sampling, the remaining test liquid in the reactor was forced to a constant temperature of 30°C through refrigerant circulation. Using a coaxial cylindrical testing system configured with a rotary rheometer, the instantaneous dynamic viscosity values ​​of each concentration gradient were tested and recorded under the condition of a constant shear rate of 100 s⁻¹. The arithmetic mean of the data collected for 3 consecutive minutes was taken as the macroscopic viscosity data at the corresponding copper ion concentration. In Table 1, the "-" recorded in the thermodynamic cloud point column of Comparative Example 1 indicates that no physical phase separation occurred in the pure inorganic acid system within the set heating range, and there was no thermodynamic cloud point boundary.

[0050] Table 1: Thermodynamic cloud point and macroscopic viscosity data of each test group at different copper ion concentrations Example 1 0.0 69.4 1.83 Example 1 24.6 63.8 1.87 Example 1 51.8 56.5 1.95 Example 1 75.2 50.1 2.01 Example 2 0.0 72.1 2.14 Example 2 24.6 66.3 2.19 Example 2 51.8 59.2 2.26 Example 2 75.2 53.4 2.38 Example 3 0.0 75.6 2.51 Example 3 24.6 68.7 2.58 Example 3 51.8 61.4 2.64 Example 3 75.2 56.8 2.75 Comparative Example 1 0.0 - 1.02 Comparative Example 1 24.6 - 1.05 Comparative Example 1 51.8 - 1.11 Comparative Example 1 75.2 - 1.16 Comparative Example 2 0.0 56.1 2.08 Comparative Example 2 24.6 41.5 2.03 Comparative Example 2 51.8 28.7 1.42 According to Table 1 and Figure 1 As shown in subplots (a) and (b), the dissolution state of the polymer in the working solution undergoes a physical change as free copper ions accumulate in the system. When the free copper ion concentration reaches 75.2 g / L, the thermodynamic cloud point of the Comparative Example 2 test group without added ethylene glycol monobutyl ether drops from the initial 56.1℃ to 21.3℃. The phase transition critical temperature of 21.3℃ directly penetrates the lower limit of the operating temperature range of 30℃, and the working solution of Comparative Example 2 undergoes phase separation and becomes turbid, with the polyethylene glycol macromolecular chains in the liquid phase agglomerating and precipitating. Corresponding to the rheological characteristics, the dynamic viscosity of Comparative Example 2 decreases after the copper ion concentration exceeds 51.8 g / L, and the system viscosity degrades to the level of a pure inorganic acid system.

[0051] In Examples 1 to 3, the cloud point remained stable between 50.1°C and 56.8°C under a free copper ion concentration of 75.2 g / L, and the liquid phase remained homogeneous. Van der Waals forces were generated between the nonpolar hydrocarbon chains of ethylene glycol monobutyl ether and the polyethylene glycol backbone, and the hydrophilic groups of ethylene glycol monobutyl ether were connected to the polar solvent through hydrogen bonds, maintaining the spatially extended conformation of the polyethylene glycol polymer in the aqueous phase and offsetting the dehydration and coagulation effect caused by hydrated copper ions competing with solvent water molecules.

[0052] At the macroscopic measurement level, the liquid phase viscosity of the system in the example did not decrease with the increase of copper ion concentration, maintaining a stable numerical output; the constant solution viscosity provided the hydrodynamic conditions for the existence of the high-viscosity Nernst diffusion layer at the copper solid-liquid interface, and the diffusion coefficient of the oxidant through the high-viscosity Nernst diffusion layer remained stable, ensuring that the micro-etching system was always in the mass transfer control reaction domain during long-term operation.

[0053] Test Example 2: Compositions A, B, and C prepared in Examples 1, 2, and 3 were used as experimental groups; working solutions prepared according to the pure inorganic acid system of Comparative Example 1 and Comparative Example 3 containing polyethylene glycol and ethylene glycol monobutyl ether but not 2-mercaptobenzimidazole were used as control groups.

[0054] A 10mm×10mm×2mm pure copper test block was used as the working electrode substrate. The electrode test surfaces were progressively polished with 400-grit to 2000-grit silicon carbide wet sandpaper, ultrasonically cleaned with deionized water and anhydrous ethanol, and then dried. The non-test surfaces were insulated and encapsulated with epoxy resin, leaving a 1cm margin. 2 The exposed test area.

[0055] Each set of test solutions was transferred to an electrochemical electrolytic cell. A standard three-electrode system was used, with a prepared pure copper sample block as the working electrode, a large-area platinum sheet as the auxiliary electrode, and a saturated calomel electrode as the reference electrode. The electrochemical workstation was connected, and the water bath jacket was started to maintain the test system at a constant temperature of 28°C.

[0056] Run the open-circuit potential scanning program to monitor the change in open-circuit potential of the working electrode until the potential fluctuation is less than 2mV for 300 consecutive seconds. Record the thermodynamic equilibrium state of adsorption at the electrode surface when the open-circuit potential fluctuation is less than 2mV.

[0057] A sinusoidal AC excitation signal with an amplitude of 10mV is superimposed on a stable open-circuit potential. The scanning frequency range is set from 100kHz to 10mHz. The real and imaginary parts of the system impedance are recorded and Nyquist plots are drawn. The charge transfer resistance data are extracted by fitting an equivalent circuit model.

[0058] After the impedance test is completed, the working electrode is left to stand in the original solution for 5 minutes. The scan rate is set to 1mV / s, and potentiodynamic polarization scan is performed in the potential range of ±250mV relative to the open circuit potential. The Tafel linear extrapolation method is used to fit the strong polarization region of the anode and cathode of the obtained polarization curve, and the self-corrosion potential and self-corrosion current density values ​​are extracted.

[0059] Table 2: Electrochemical kinetic parameters of pure copper under working solution conditions in each test group Example 1 -0.125 2.45 185.6 Example 2 -0.118 2.31 201.4 Example 3 -0.104 2.08 215.8 Comparative Example 1 -0.287 45.28 5.2 Comparative Example 3 -0.211 28.74 14.8 According to Table 2 and Figure 2 Data from subplots (a) and (b) show that in the Comparative Example 1 system based on inorganic acid and hydrogen peroxide, the charge transfer resistance of the pure copper electrode is 5.2 Ω·cm. 2 The corresponding self-corrosion current density reaches 45.28 mA / cm². 2The self-corrosion current density data indicate that the activation energy of the reaction on the exposed copper surface is low in a strong oxidizing environment, and the electron exchange rate at the solid-liquid interface is high. Continuous micro-corrosion processes in industrial settings are often accompanied by localized heating. After introducing polymer components such as polyethylene glycol into the system, the charge transfer resistance of Comparative Example 3 increased to 14.8 Ω·cm. 2 The self-corrosion current density decreased to 28.74 mA / cm². 2 ; The physical boundary layer formed by the polymer on the electrode surface increases the mass transfer resistance of reactant ions, causing local electrochemical reaction rates to converge, but the overall polarization potential shift of the system is limited. In Examples 1 to 3, 2-mercaptobenzimidazole was added to the systems, and the measured charge transfer resistance values ​​were distributed at 185.6 Ω·cm. 2 Up to 215.8 Ω·cm 2 Between these points, the self-corrosion current density decreased to 2.08 mA / cm². 2 Up to 2.45 mA / cm 2 In the range, the self-corrosion potential shifts in the positive direction; the thiol sulfur atom and the imidazole ring nitrogen atom in the 2-mercaptobenzimidazole molecule provide lone pair electrons, which penetrate the outer polymer diffusion layer under the action of ethylene glycol monobutyl ether and chemically coordinate with the copper matrix.

[0060] During the processing of rolled copper foil, a large number of dislocations accumulate at the grain boundaries and microcracks, forming high free energy microregions. 2-Mercaptobenzimidazole molecules undergo coordination adsorption in these high free energy microregions and form steric hindrance, increasing the activation energy corresponding to intergranular dissolution. Under the depolarization effect of trace chloride ions, the dissolution process in the flat crystal region can continue. The microscopic competitive adsorption mode of high and low energy surfaces causes changes in macroscopic polarization data, and the difference in dissolution rate between the grain boundaries and the grain interior gradually narrows. The overall reaction is maintained in the low current range at the kinetic level, which reduces the phenomenon of excessive intergranular dissolution in the corresponding physical processing results.

[0061] Test Example 3: Take 50L of each of the working solutions prepared according to the methods of Example 2, Comparative Example 5 which uses a timed fixed feeding method and has no redox potential control system, and Comparative Example 6 which has no glycine and only pulse injection of hydrogen peroxide replenishment solution, and inject them into three miniature simulation test tanks equipped with automated metering pumps and closed-loop circulation pipelines; start the circulation system and maintain the tank solution temperature at 30°C.

[0062] A continuous strip of rolled copper foil was introduced into the test tank at a constant linear speed of 10 m / min for continuous micro-etching. After the system had been running smoothly for 2 hours, the width of the rolled copper foil fed into the micro-etching tank was doubled and fed continuously for 3 minutes while maintaining the linear speed, thus creating a high-load transient disturbance condition.

[0063] The high-load disturbance condition is triggered at t=0. Within a time window from t=-300s to t=1200s, the instantaneous concentration of free copper ions and the redox potential value in the system are continuously acquired and recorded at a sampling rate of 1Hz using a copper ion selective electrode and a redox potential probe in the flow cell. The programmable logic controller synchronously calculates the time first derivative of the redox potential, records the extreme values ​​of the derivative, and records the response time required for the system to restore the time first derivative to a stable baseline of -0.5 to 0.5mV / min.

[0064] At two points, immediately before the disturbance is triggered (t=0) and at the end of the disturbance test period (t=1200s), 10 mL of working solution samples were removed from the main test tank. The samples were subjected to redox titration using a 0.1 mol / L potassium permanganate standard solution under acidic conditions to determine the total amount of hydrogen peroxide actually consumed in the system. The theoretical hydrogen peroxide consumption was calculated by combining the mass loss of the input copper foil during the high-load transient disturbance condition. The difference between the actual consumption and the theoretical consumption was divided by the actual consumption to calculate the ineffective decomposition rate of hydrogen peroxide under the high-load transient disturbance condition.

[0065] Table 3: Disturbance resistance and hydrogen peroxide consumption data for each test group under sudden high-load disturbance conditions Example 2 1.14 -7.1 43 4.2 Comparative Example 5 6.82 -15.4 312 28.5 Comparative Example 6 8.95 -22.3 >1200 41.7 According to Table 3 and Figure 3 The data from neutron plot (a) and subplot (b) show that during continuous industrial operation, the local high-load etching reaction instantaneously releases a large number of nascent copper ions into the system, directly altering the original thermodynamic equilibrium of the liquid phase system. Observing the data output of Comparative Example 6, since glycine was not introduced as a ligand in the working solution of Comparative Example 6, after the measurement and control system detected the negative abrupt change signal of the redox potential and injected hydrogen peroxide, the concentration of free copper ions in the test tank still showed an upward trend after the disturbance was triggered, with the peak value of free copper ions reaching 8.95 g / L.

[0066] Free copper ions exhibit catalytic activity in the decomposition of hydrogen peroxide in acidic environments. Figure 3 (b) The hydrogen peroxide concentration curve of Comparative Example 6 decreased exponentially, and the ineffective decomposition rate calculated by potassium permanganate titration reached 41.7%. The system did not converge to the initial baseline state within the 1200-second observation period. Comparative Example 5 test group, which contained glycine additive but did not introduce redox potential first derivative feedforward control logic, relied on a fixed mechanical time period for the feeding system of Comparative Example 5 to operate. The measurement and control unit lacked the ability to respond instantaneously to sudden thermodynamic disturbances in the test tank.

[0067] During the high-load transient disturbance period, the peak concentration of free copper ions accumulated to 6.82 g / L, and the corresponding extreme value of the negative derivative of the redox potential reached -15.4 mV / min. The reaction system took 312 seconds to re-establish coordination equilibrium during the subsequent feeding action, during which 28.5% of hydrogen peroxide was ineffectively decomposed. Example 2 showed different kinetic characteristics under the same external disturbance conditions. The time first derivative of the redox potential was introduced into the calculation of the programmable logic controller as a precursor variable. When the system determined that the first derivative reached the preset threshold at a rate of -6.5 mV / min, the control logic instantaneously started the proportional metering pump and synchronously pulsedly injected hydrogen peroxide and glycine solution into the tank.

[0068] Figure 3 (a) The data trajectory shows the chemical coordination process after glycine intervention. The free copper ions newly dissolved at the etched interface are coated with amino and carboxyl structures to form chelates. The peak concentration of free copper ions in the system is limited to 1.14 g / L, which is below the lower limit of the concentration that induces runaway decomposition of hydrogen peroxide. The closed-loop control based on transient derivative linkage shortens the recovery time of the system to 43 seconds, inhibits the autocatalytic decomposition reaction, and the actual measured ineffective decomposition rate of hydrogen peroxide is controlled at 4.2%. The feedforward control logic of the first derivative of redox potential maintains the chemical stability of the oxidant under harsh conditions by adjusting the instantaneous coordination balance.

[0069] Test Example 4: The rolled copper foil obtained after being continuously treated for 1 hour with the working fluids corresponding to Examples 1, 2, and 3, as well as Comparative Example 1 (a pure inorganic acid system) and Comparative Example 4 (a system without forced cooling and immersion fluid distributor, relying on natural cooling and unpressurized liquid injection), was used as test samples.

[0070] A strip of test sample, 2 meters long and 0.5 meters wide, was cut along the machine conveyor belt of the test sample roll. Fifty independent test units with an area of ​​1 cm × 1 cm were evenly divided on the surface of the test sample using a grid method.

[0071] A high-precision stylus-type surface roughness measuring instrument was used, with the stylus scanning speed set to 0.5 mm / s and the evaluation length set to 4.0 mm, to perform unidirectional scanning on each test unit.

[0072] The arithmetic mean roughness and the height of the ten micro-unevenness points of the 50 test units were extracted one by one.

[0073] Summarize the discrete sampling data, calculate and record the arithmetic mean and corresponding standard deviation of the two roughness indices for each group of samples.

[0074] Table 4: Roughness and uniformity values ​​of rolled copper foil surfaces after continuous processing in each test group Example 1 0.134 0.012 0.85 0.06 Example 2 0.125 0.010 0.78 0.05 Example 3 0.128 0.011 0.82 0.05 Comparative Example 1 0.586 0.124 3.45 0.58 Comparative Example 4 0.312 0.087 1.94 0.31 According to Table 4 and Figure 4 As shown in subplots (a) and (b), the average arithmetic mean roughness of the copper foil surface treated in Comparative Example 1, which operates under a pure inorganic acid system, reaches 0.586 μm, the average height of the ten micro-irregularities reaches 3.45 μm, and the standard deviation of the arithmetic mean roughness is 0.124 μm. The inorganic acid system does not form a high-viscosity diffusion layer at the solid-liquid interface of the copper foil, and the redox reaction of hydrogen peroxide is dominated by chemical reaction kinetics.

[0075] The high dislocation density at the grain boundaries of rolled copper foil and the low local reaction activation energy, coupled with the lack of competitive adsorption mechanisms, led to anisotropic dissolution during etching. The intergranular dissolution rate was higher than that within the grains, resulting in macroscopically varying depths of etch pits. This resulted in low overall surface smoothness and fluctuating values. Comparative Example 4 incorporated complete organic components into its formulation but did not employ an external forced fluid distribution and cooling circulation system. Under natural flow conditions, the thickness of the polymer diffusion layer on the copper surface was affected by natural convection and local reaction exothermics, exhibiting an irregular thickness distribution.

[0076] The arithmetic mean roughness of Comparative Example 4 decreased to 0.312 μm. Due to the instability of the hydrodynamic boundary, the standard deviation of the roughness data remained at 0.087 μm, indicating that the surface smoothing effect was non-uniform on the entire wide surface. The measurement data of Examples 1 to 3 showed convergence characteristics. Under the combined action of the formulation components and the specific physical shear force of immersion, the polyethylene glycol molecular chains constructed a uniform viscous Nernst diffusion layer on the copper foil surface. The micro-etching system was in the mass transfer diffusion control domain. The original micro-protrusions on the copper surface penetrated the diffusion layer shallowly and dissolved rapidly upon contact with the high concentration of oxidant. The dissolution of deeper micro-pits was limited due to the long mass transfer path. The steric coordination of 2-mercaptobenzimidazole in the high-energy region of the grain boundary reduced the reaction rate difference between grains.

[0077] In the physical measurement results, the arithmetic mean roughness of the example group was controlled within the range of 0.125 μm to 0.134 μm. The standard deviation of the arithmetic mean roughness and the standard deviation of the ten-point height of the micro-irregularity, which reflect the degree of dispersion, were reduced by an order of magnitude. The micro-reaction field achieved stable and controlled isotropic dissolution on a continuous industrial scale.

[0078] Test Example 5: The rolled copper foils obtained after being continuously treated for 1 hour with the working solutions corresponding to Examples 1, 2, and 3, as well as Comparative Example 1 (a pure inorganic acid system) and Comparative Example 3 (a system containing a polymer but not 2-mercaptobenzimidazole) were used as experimental subjects.

[0079] Using a dedicated high-precision cutting machine, strips of 15mm × 150mm in size were cut along the machine conveyor belt direction and transverse direction of each group of rolled copper foil. Five samples were prepared in parallel in each direction for each test group.

[0080] All the cut strip samples were placed in a constant temperature and humidity chamber set at 23°C and 50% relative humidity and allowed to stand for 24 hours to equilibrate.

[0081] The balanced specimens were sequentially loaded into the test fixture of the MIT flexural fatigue strength tester; the constant tension load of the upper fixture was set to 4.9N, the curvature radius of the folding table was set to 0.38mm, the alternating bending frequency was set to 175 times / min, and the bending angle was 135 degrees to the left and right of the centerline.

[0082] The tester is started to continuously alternate bending the sample. When the sample completely breaks in the bending area and the tension fails, the instrument stops running and records the total number of bends. The single test values ​​of all samples are summarized and the arithmetic mean of each group in different directions is calculated.

[0083] Table 5: Test data of MIT folding fatigue life of rolled copper foil in the machine conveyor direction and transverse direction for each test group Example 1 Machine belt direction 8512 8439 8605 8573 8486 8523 Example 1 Horizontal 8124 8067 8192 8051 8145 8116 Example 2 Machine belt direction 8746 8813 8695 8762 8821 8767 Example 2 Horizontal 8311 8405 8289 8364 8327 8339 Example 3 Machine belt direction 8654 8702 8618 8596 8691 8652 Example 3 Horizontal 8234 8219 8275 8198 8251 8235 Comparative Example 1 Machine belt direction 642 689 615 657 631 647 Comparative Example 1 Horizontal 563 592 548 581 557 568 Comparative Example 3 Machine belt direction 1845 1793 1876 1822 1851 1837 Comparative Example 3 Horizontal 1682 1714 1695 1731 1658 1696 According to Table 5 and Figure 5 Data from neutron plot (a) and subplot (b) show that the numerical differences in macroscopic mechanical parameters correspond to the physical externalization of the corrosion state at the microcrystalline interface; in Comparative Example 1 of the inorganic acid system, the fatigue bending life of the rolled copper foil is extremely low, with an average of 647 cycles in the machine conveyor direction; when the flexible printed circuit board material undergoes alternating strain, the internal fracture of the flexible printed circuit board material originates from the stress concentration area at the surface defect.

[0084] Pure inorganic acid micro-etching solutions lack steric constraint in dissolving metal surfaces. Microcracks and high-density dislocation regions extending along grain boundaries have reaction free energies higher than those within the grains. The etching solution extends longitudinally along the intergranular space, and the V-shaped intergranular grooves left on the copper surface evolve into fatigue cracks under alternating tension, leading to sample fracture. Comparative Example 3, which incorporates a polyethylene glycol diffusion layer in its formulation, achieved a machine conveyor belt life of 1837 cycles. The macroscopic fluid boundary layer provides overall mass transfer resistance, inhibiting local dissolution, but the physical barrier layer fails to recognize the differences between high and low energy crystal planes, and the anisotropic intergranular corrosion mechanism still exists. The average number of flexural cycles for samples from Examples 1 to 3 exceeded 8500 cycles.

[0085] 2-Mercaptobenzimidazole penetrates the liquid-phase diffusion layer to reach the copper solid-liquid interface. 2-Mercaptobenzimidazole constructs steric hindrance for chemical coordination at high-energy regions such as grain boundaries and dislocations, increasing the activation energy barrier for micro-region dissolution. The change in polarization conditions transforms the system from anisotropic intergranular corrosion to isotropic surface dissolution. Micro-etching removes mechanical indentations and loose crystals from the surface of the rolled copper foil without generating new intergranular microcrack defect sources. The intact grain morphology reduces stress concentration during alternating bending, correspondingly increasing the deformation energy consumed in the crack initiation stage, resulting in an increase in fatigue life. The stable output of physical and mechanical data reflects the engineering characteristics of micro-interface reaction remodeling.

[0086] Test Example 6: The rolled copper foils obtained after being continuously treated for 1 hour with the working solutions corresponding to Examples 1, 2, and 3, as well as Comparative Example 1 (a pure inorganic acid system) and Comparative Example 3 (containing a polymer but without 2-mercaptobenzimidazole) were used as experimental subjects.

[0087] The treated surfaces of each group of rolled copper foils were laminated with a 25μm thick polyimide film and placed in a vacuum hot press. The film was kept at constant temperature and pressure for 60 minutes at 185℃ and 3.5MPa to prepare a single-sided flexible copper-clad laminate sample.

[0088] Using standard photolithography and ferric chloride etching processes, parallel test lines with a width of 3.0 mm were fabricated on the surface of each group of flexible copper-clad laminate samples, with 15 independent test lines prepared for each group of samples.

[0089] The 15 test lines in each group were divided into three test batches. The first batch was kept in a normal initial control environment of 23℃ and 50% relative humidity. The second batch was moved into a high temperature aging test chamber and continuously exposed at 150℃ for 168 hours. The third batch was transferred to a constant temperature and humidity test chamber and exposed at 85℃ and 85% relative humidity for 168 hours.

[0090] After the test sample reaches the set environmental exposure period, it is taken out and left to stand for 2 hours to recover. Then it is loaded onto the 90-degree peel test fixture of the universal testing machine. The peel rate is set to 50 mm / min. The load-displacement data during the peel process are continuously recorded. The average load in the stable peel range is extracted and divided by the line width to obtain the interface peel strength value.

[0091] Table 6: 90-degree peel strength data of flexible copper-clad laminates in various service environments for each test group Example 1 1.18 1.12 1.05 11.0 Example 2 1.22 1.15 1.09 10.7 Example 3 1.15 1.07 1.02 11.3 Comparative Example 1 1.04 0.61 0.38 63.5 Comparative Example 3 1.11 0.82 0.64 42.3 According to Table 6 and Figure 6Data from neutron plot (a) and subplot (b) show that in the Comparative Example 1 system etched with pure inorganic acid, the initial peel strength was measured to be 1.04 N / mm under normal conditions. The peel strength of 1.04 N / mm depends on the physical and mechanical interlocking generated by the macroscopic rough morphology between the interfaces. As the service environment changes to a high temperature and high humidity state, the V-shaped intergranular grooves left on the surface of the rolled copper foil during the inorganic etching period become the origin of stress concentration. The polymer resin on the substrate side did not completely expel the gas at the bottom of the extremely narrow gap during the pressing stage. Under the dual 85 operating conditions, water vapor condenses in the cavity and establishes a local vapor pressure. The mechanical interlocking at the interface fails to peel off, and the damp heat environment attenuation rate of Comparative Example 1 reaches 63.5%.

[0092] observe Figure 6 (b) The recorded transient peeling curves show that the linear load in Comparative Example 1 during the tearing process exhibits stick-slip peeling characteristics. The rise in load peak corresponds to the sticking resistance of deeper pits in the local area. The sudden drop in load reflects the interface failure at the stress concentration point. The separation of the material layer shows discontinuity.

[0093] Comparative Example 3 introduced a polymer diffusion layer, which partially suppressed the etching depth and correspondingly improved the peel strength data under thermal and damp heat aging, but still showed a 42.3% damp heat attenuation. The data trajectory of the Example group maintained stable output under three environmental stress states. The steric hindrance effect of the polymer diffusion layer combined with 2-mercaptobenzimidazole reshaped the interface etching dynamics, suppressed deep grain boundary corrosion on the copper surface, and transformed the overall morphology into a uniformly distributed shallow pit. During the hot-pressing composite stage, the molten polyimide resin filled the pits, eliminating the space for interfacial gas to reside. The initial peel strength of the Example group was between 1.15 N / mm and 1.22 N / mm, and remained above 1.02 N / mm after 168 hours of double 85 exposure, with the attenuation rate controlled within 11.3%.

[0094] Figure 6 (b) The instantaneous peeling curve of Example 2 remains stable. The uniform micro-geometric topography evenly distributes the external tearing load to the two-dimensional adhesion surface, eliminating the local peak stress that causes local damage to the interface. The overall copper-clad laminate material establishes service reliability in hydrothermal environment.

[0095] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for controlling the surface roughness of rolled copper foil, characterized in that, Includes the following steps: The initial rolled bare copper foil is fed into the degreasing section through a continuous conveying system for spray degreasing and water washing pretreatment to obtain pretreated rolled copper foil. The pretreated rolled copper foil is fed into a micro-etching tank containing a working fluid, which is a multi-component synergistic micro-etching composition. The working fluid in the micro-etching main tank is extracted and introduced into an external heat exchanger to force cooling and stabilize to the first target temperature, thus obtaining the cooled working fluid. The cooled working fluid is pumped into an immersion fluid distributor installed below the liquid surface of the micro-etching main tank, and the upper and lower surfaces of the traveling rolled copper foil are vertically impacted with a set spray pressure, so that the temperature of the micro-reaction zone on the surface of the rolled copper foil is locked at the second target temperature. During the operation of the micro-etching main tank, an automated closed-loop control is initiated to introduce the working fluid into an external detection flow cell equipped with an ultrasonic transducer. The oxidation-reduction potential signal of the working fluid is continuously read as an effective instantaneous value, and the time first derivative of the filtered oxidation-reduction potential value is calculated in real time. When the calculated first time derivative exceeds the set system warning threshold, the metering pump is triggered to synchronously pulse-inject hydrogen peroxide replenishment solution and glycine solution into the micro-etching main tank until the first time derivative returns to the stable baseline. After leaving the micro-etching tank, the rolled copper foil enters the water washing section for cleaning. After removing moisture and baking, the finished rolled copper foil is obtained.

2. The method for controlling the surface roughness of rolled copper foil according to claim 1, characterized in that, The preparation method of the multi-component synergistic micro-etching composition includes the following steps: Inject 900 to 1100 parts by weight of deionized water into the mixing vessel, and add 100 to 120 parts by weight of concentrated sulfuric acid dropwise while stirring, controlling the system temperature within the range of 29 to 36°C while stirring. Add 2.0 to 4.0 parts by weight of polyethylene glycol and 10 to 20 parts by weight of glycine in sequence, and stir at a temperature range of 29 to 36°C until the solid is completely dissolved; In a separate auxiliary tank, 0.05 to 0.1 parts by weight of 2-mercaptobenzimidazole are added to 5.0 to 8.0 parts by weight of ethylene glycol monobutyl ether and stirred in a closed container at a temperature range of 24 to 31°C until completely dissolved to form a homogeneous transparent solution. The mixture is then injected into a dispensing tank. Add 0.025 to 0.05 parts by weight of sodium chloride to the mixing vessel and stir; then cool to 21 to 26°C, add 35 to 50 parts by weight of hydrogen peroxide and stir to obtain the multi-component synergistic micro-etching composition.

3. The method for controlling the surface roughness of rolled copper foil according to claim 2, characterized in that, In the preparation method of the multi-component synergistic micro-etching composition, the stirring speed is set to 150 to 180 rpm; the rate of injecting the mixture into the mixing vessel is 1.5 to 2.5 parts / min.

4. The method for controlling the surface roughness of rolled copper foil according to claim 1, characterized in that, The specific process for pretreatment involving spray degreasing and water washing includes: Rolled bare copper foil with an initial surface roughness of 1.5 to 2.0 μm is fed into the degreasing section at a linear velocity of 8 to 12 m / min. It is sprayed with a sodium hydroxide aqueous solution with a mass fraction of 4% to 6% at a temperature of 38 to 42°C for 15 to 30 seconds, followed by spray washing with deionized water at a pressure of 0.2 to 0.3 MPa, and the surface free water is drained.

5. The method for controlling the surface roughness of rolled copper foil according to claim 1, characterized in that, During the process of extracting and cooling the working fluid and pumping it into the submersible fluid distributor for vertical impact, the control parameters for the physical flow field and temperature of the working fluid are as follows: The working fluid is drawn out using a centrifugal pump at a flow rate of 300 to 500 L / min and introduced into an external titanium plate heat exchanger. The first target temperature is 26 to 28°C; The distance between the nozzle of the distributor and the surface of the rolled copper foil is 30 to 50 mm, and the spraying pressure is 0.15 to 0.25 MPa; the total processing time of the rolled copper foil in the micro-etching main tank is 45 to 60 seconds; The second target temperature is 28 to 32°C.

6. The method for controlling the surface roughness of rolled copper foil according to claim 1, characterized in that, The specific process of initiating automated closed-loop control for signal reading and calculation includes: The working fluid in the micro-etching main tank is introduced into the external detection flow cell at a flow rate of 2 to 5 L / min via a bypass circulation pump. The flow cell is equipped with an online probe for the redox potential of a platinum electrode. The ultrasonic transducer inside the flow cell operates at a frequency of 40kHz and activates ultrasonic oscillation for 10 to 15 seconds every 5 minutes. The programmable logic controller system continuously reads signals at a sampling frequency of 1 to 2 Hz. Through an embedded moving average filtering algorithm, it takes the average value of the redox potential signal over 10 to 15 consecutive seconds as the effective instantaneous value and calculates the first derivative of time.

7. The method for controlling the surface roughness of rolled copper foil according to claim 1, characterized in that, During the process of triggering the metering pump to synchronously pulse-inject hydrogen peroxide replenishment solution and glycine solution into the micro-etching main tank: The set system warning threshold is -5mV / min to -8mV / min; When the metering pump is triggered, the molar ratio of hydrogen peroxide to glycine injected in a pulse is kept constant within the range of 3:1 to 4:

1. The stable baseline is defined as the time-first derivative recovering to 0 mV / min.

8. The method for controlling the surface roughness of rolled copper foil according to claim 1, characterized in that, The specific process of the rolled copper foil entering the water washing section for cleaning after leaving the micro-etching main tank, as well as subsequent dehydration and baking, includes: The surface moisture is removed by squeezing with countercurrent deionized water at 0.2 to 0.3 MPa for 15 to 20 seconds. After that, it is sent into a hot air circulating oven and baked at 80 to 100°C for 10 to 20 seconds.

9. The method for controlling the surface roughness of rolled copper foil according to claim 2, characterized in that, In the preparation method of the multi-component synergistic micro-etching composition, the rate of adding concentrated sulfuric acid is 15 to 25 parts / min, and the rate of adding hydrogen peroxide is 8 to 12 parts / min.

10. The method for controlling the surface roughness of rolled copper foil according to claim 2, characterized in that, In the preparation method of the multi-component synergistic micro-etching composition, the addition rate of 2-mercaptobenzimidazole to ethylene glycol monobutyl ether is 0.01 to 0.02 parts / min, and the stirring time is 10 to 15 minutes.

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