A method for manufacturing a high-conductivity hvlp copper foil

Abstract

The present application belongs to the technical field of copper foil preparation for printed circuit board, and discloses a preparation method of high-conductivity HVLP copper foil, which comprises an electrolytic foil forming stage and a multi-step surface treatment process. In the electrolytic foil forming stage, a foil additive system composed of hydroxyethyl cellulose, gelatin, polydithiodipropyl sulfone sodium, polyethylene glycol and chloride ions is introduced into the copper sulfate electrolyte to realize compact deposition and grain structure regulation of the copper foil. In the surface treatment stage, the original foil is sequentially subjected to first roughening, first solidification, second roughening, second solidification, blackening, graying, passivation and silane coupling agent coating treatment. In the roughening process, a roughening additive system composed of aliphatic sulfonated condensate and polyether compound is used to maintain a low surface profile while building a uniform and stable micro bonding structure. Through the above process, HVLP copper foil with low profile, high conductivity and good bonding performance can be prepared.

Description

Technical Field

[0001] This invention belongs to the field of copper foil preparation technology for printed circuit boards, and specifically relates to a method for preparing high conductivity HVLP copper foil. Background Technology

[0002] High-frequency, high-speed electrolytic copper foil (HVLP) is widely used in high-frequency, high-speed circuit boards due to its low surface profile and high bonding strength. Under high-frequency signal transmission conditions, due to the skin effect, current is mainly concentrated on the conductor surface. Increased surface roughness of the copper foil leads to enhanced signal reflection and scattering, resulting in increased transmission loss. Current HVLP copper foil manufacturing processes typically include two main stages: electrolytic foil formation and surface treatment. In the foil formation stage, grain refiners, leveling agents, and inhibitors are introduced into the copper sulfate electrolyte to achieve dense copper foil deposition and grain structure control. In the surface treatment stage, a roughening and curing electrochemical process is used to construct a microscopic nodular structure on the copper foil surface while maintaining a low macroscopic profile, thereby improving the bonding performance between the copper foil and the resin substrate.

[0003] CN110453252B discloses a method for manufacturing HVLP copper foil for high-frequency, high-speed copper-clad laminates. This method employs an additive system containing hydrolyzed collagen, sodium polydithiopropane sulfonate, polyethylene glycol, and chloride ions during the foil-making stage, and incorporates multiple roughening and curing processes in subsequent surface treatment to achieve precise control of the copper foil surface structure. CN114990654B proposes an electrolytic copper foil surface treatment process that introduces heteropolyacid salts and sulfur-containing amino acid additives into the roughening and curing solutions to construct nanoscale nodular structures on the copper foil surface, meeting the bonding performance requirements under low roughness conditions. However, existing technologies generally suffer from complex process flows and numerous additive systems, placing higher demands on process stability and cost control in actual production. Furthermore, the residue of some organic additives in the copper foil can affect the conductivity of copper. Summary of the Invention

[0004] To address the shortcomings mentioned in the background art, the present invention aims to provide a method for preparing high-conductivity HVLP copper foil. By introducing a specific foil additive system during the electrolytic foil production stage and employing a roughening additive system containing aliphatic sulfonated condensates and polyether compounds during the surface treatment stage, the method maintains the low surface profile of the copper foil while ensuring its conductivity, thereby achieving a relatively simplified process and stable overall performance in the preparation of HVLP copper foil.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing a highly conductive HVLP copper foil includes the following steps:

[0007] S1. Electrolytic foil electrolyte is injected into an electrolytic cell, with a titanium roller as the cathode and a lead-silver alloy plate as the anode. Direct current is applied to perform electrolytic deposition to obtain the original foil.

[0008] The electrolyte for the electrolytic foil contains a foil additive system, which is composed of hydroxyethyl cellulose, gelatin, sodium polydithiopropane sulfonate, polyethylene glycol, and chloride ions.

[0009] S2. The original foil is subjected to a first roughening treatment, a first curing treatment, a second roughening treatment, a second curing treatment, a blackening treatment, an ashing treatment, a passivation treatment, and a silane coupling agent coating treatment in sequence.

[0010] The roughening liquid used in the first and second roughening treatments contains a roughening additive system, which is composed of aliphatic sulfonated condensates and polyether compounds.

[0011] S3. The copper foil coated with the silane coupling agent is washed and dried to obtain a highly conductive HVLP copper foil.

[0012] More preferably, the addition amounts of each component in the raw foil additive system in step S1 are as follows: hydroxyethyl cellulose 0.5~2.0ppm, gelatin 90~130ppm, sodium polydithiopropane sulfonate 40~68ppm, polyethylene glycol 10~30ppm, and chloride ions 25~35ppm.

[0013] More preferably, the molecular weight of the gelatin in step S1 is 10,000 to 15,000 Daltons, and the molecular weight of the polyethylene glycol is 8,000 to 12,000 Daltons.

[0014] More preferably, the Cu in the electrolyte of the electrolytic green foil in step S1 2+ The concentration of H2SO4 is 85~100g / L, and the concentration of H2SO4 is 90~120g / L; the process parameters for the electrolytic foil production step are: electrolyte temperature 50±5℃, current density 30000~48000A / dm³. 2 Electrolysis time: 3-6 seconds.

[0015] More preferably, in step S2, the amounts of each component in the roughening additive system added to the roughening liquid used in the first roughening treatment and the second roughening treatment are: 0.2-0.8 ppm of aliphatic sulfonated condensate and 0.2-1.0 ppm of polyether compound; and the chloride ion concentration in the roughening liquid used in the second roughening treatment is 10-40 ppm.

[0016] More preferably, the aliphatic sulfonated condensate is selected from one or more of sulfonated acetone formaldehyde condensate, sulfonated butanone formaldehyde condensate, and sulfonated cyclohexanone formaldehyde condensate, and its molecular weight is 2000~10000 Daltons.

[0017] The polyether compound is selected from one or more of polyethylene glycol, polypropylene glycol, polyethylene glycol methyl ether, polyoxyethylene polyoxypropylene, polyoxyethylene alkyl ether, and polyethylene oxide, and its molecular weight is 6,000 to 10,000 Daltons.

[0018] More preferably, in step S2, the process parameters for the first roughening treatment and the second roughening treatment are as follows:

[0019] The process parameters for the first roughening treatment are: temperature 28±2 ℃, current density 15~30 A / dm. 2 Inlet flow rate: 6–12 m³ 3 / h, processing time 3-6 s, and Cu in the first roughening solution 2+ The concentration of [unspecified substance] is 10–20 g / L, and the concentration of H2SO4 is 150–200 g / L;

[0020] The process parameters for the second roughening treatment are: temperature 28±2 ℃, current density 8~12 A / dm. 2 Inlet flow rate: 6–12 m³ 3 / h, processing time 3-6 s, and Cu in the second roughening solution 2+ The concentration of the substance is 10–20 g / L, and the concentration of H2SO4 is 150–200 g / L.

[0021] More preferably, in step S2, the process parameters for the first curing treatment and the second curing treatment are as follows:

[0022] The process parameters for the first curing treatment are: temperature 40±5 ℃, liquid flow rate 10~20 m³ / h. 3 / h, current density 15~25 A / dm 2 The processing time is 3-6 seconds, and the Cu in the first curing solution... 2+ The concentration of [unspecified substance] is 50–60 g / L, and the concentration of H2SO4 is 90–130 g / L;

[0023] The process parameters for the second curing treatment are: temperature 40±5 ℃, liquid flow rate 10~20 m³ / h. 3 / h, current density 15~20 A / dm 2 The processing time is 3-6 seconds, and the Cu in the second curing solution... 2+ The concentration of HCl is 50–60 g / L, and the concentration of H2SO4 is 90–130 g / L.

[0024] More preferably, in step S2, the process parameters for the blackening treatment and the ashing treatment are as follows:

[0025] The process parameters for the blackening treatment are: temperature 38±2 ℃, liquid flow rate 8~16 m³ / s. 3 / h, current density 3~5A / dm 2 Processing time: 3-6 seconds;

[0026] The process parameters for the ashing treatment are: temperature 40±2 ℃, liquid flow rate 8~16 m³ / s. 3 / h, current density 8~10 A / dm 2 Processing time: 3-6 seconds.

[0027] More preferably, in step S2, the passivation process parameters are: temperature 28±2 ℃, and influent flow rate 4~18 m³ / s. 3 / h, current density 15~200 A / dm 2 The processing time is 3–6 s, and the concentration of hexavalent chromium ions in the passivation solution is 1.0–1.3 g / L;

[0028] The silane coupling agent used in the silane coupling agent coating treatment is 3-glycidyl etheroxypropyltrimethoxysilane, and its coating concentration is 1.8 g / L.

[0029] The beneficial effects of this invention are:

[0030] This invention introduces a foil-forming additive system composed of hydroxyethyl cellulose, gelatin, sodium polydithiopropane sulfonate, polyethylene glycol, and chloride ions during the electrolytic foil-forming stage. Through the synergistic adsorption and regulation of various organic components at the copper deposition interface, uniform nucleation and controlled growth of copper grains are achieved, which is beneficial for forming a dense and continuous copper foil matrix structure. This reduces the intrinsic surface roughness while avoiding the adverse effects of excessive grain refinement on the integrity of the copper lattice and conductivity. In the surface treatment stage, this invention uses an additive system composed of aliphatic sulfonated condensates and polyether compounds in the roughening process. This system provides stable electrochemical adsorption sites through sulfonic acid groups and forms a moderate steric hindrance effect at the deposition interface with the help of the aliphatic backbone and polyether structure. This makes the distribution of the microscopic nodular structures formed during the roughening process more uniform and the scale more controllable, effectively increasing the effective contact area of ​​the copper foil surface while maintaining the macroscopic low profile characteristics. Compared to traditional processes that rely on repeated roughening or complex inorganic additive systems, the roughening control method employed in this invention reduces process complexity while improving process stability and repeatability. Furthermore, by incorporating appropriate curing, alloying, passivation, and silane coupling agent coating steps in subsequent processing steps, this invention can further enhance the heat resistance, oxidation resistance, and interfacial stability between the copper foil and the resin substrate without increasing the process burden. Attached Figure Description

[0031] The invention will now be further described with reference to the accompanying drawings.

[0032] Figure 1 The SEM image of the HVLP copper foil sample prepared in Example 3 of this invention is magnified 3000 times.

[0033] Figure 2 The SEM image of the HVLP copper foil sample prepared in Comparative Example 1 of this invention is magnified 3000 times. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1: A method for preparing a highly conductive HVLP copper foil, which is carried out according to the following steps.

[0036] S1. A copper sulfate electrolyte is injected into an electrolytic cell, using a titanium roller as the cathode and a lead-silver alloy plate as the anode, and a direct current is applied to perform electrolytic deposition to prepare the raw foil. The electrolyte for electrolytic deposition of the raw foil contains Cu... 2+The concentration of the electrolyte was 85 g / L, the concentration of H2SO4 was 90 g / L, and a raw foil additive system was added, comprising 0.5 ppm hydroxyethyl cellulose, 90 ppm gelatin, 40 ppm sodium dithiopropane sulfonate, 10 ppm polyethylene glycol, and 25 ppm chloride ions. The molecular weight of the gelatin was 10,000 Daltons, and the molecular weight of the polyethylene glycol was 8,000 Daltons. During the electrolysis of the raw foil, the electrolyte temperature was controlled at 45 °C, and the current density was controlled at 30,000 A / dm³. 2 The electrolysis time is 3 seconds.

[0037] S2. The above-mentioned electrolytic foil is subjected to a first roughening treatment, a first curing treatment, a second roughening treatment, a second curing treatment, a blackening treatment, an ashing treatment, a passivation treatment, and a silane coupling agent coating treatment in sequence.

[0038] The first roughening treatment employs a roughening solution containing a roughening additive system, wherein Cu in the roughening solution... 2+ The concentration of [unspecified substance] was 10 g / L, the concentration of H2SO4 was 150 g / L, and the amount of aliphatic sulfonated condensate sulfonated acetone-formaldehyde condensate added to the roughening additive system was 0.2 ppm, and the amount of polyether compound polyethylene glycol added was 0.2 ppm. The process conditions for the first roughening treatment were: temperature 26 ℃, current density 15 A / dm³. 2 Inlet flow rate 6 m 3 / h, processing time 3 seconds.

[0039] The first curing process is then carried out, in which Cu is added to the curing solution. 2+ The concentration of the active ingredient was 50 g / L, the concentration of H2SO4 was 90 g / L, the curing temperature was 40 ℃, and the influent flow rate was 10 m³ / L. 3 / h, current density is 15 A / dm 2 The processing time is 3 seconds.

[0040] The Cu in the roughening solution used in the second roughening treatment 2+ The concentration of [unspecified substance] was 10 g / L, the concentration of H2SO4 was 150 g / L, the concentration of chloride ions was 10 ppm, and 0.2 ppm of sulfonated acetone-formaldehyde condensate and 0.2 ppm of polyethylene glycol were added simultaneously. The second roughening treatment was carried out at a temperature of 26 ℃ and a current density of 8 A / dm³. 2 The inlet flow rate is 6 m³ / s. 3 / h, processing time is 3 s.

[0041] Immediately after the second roughening treatment, the second curing treatment is carried out. The composition of the curing solution and the process conditions used in the second curing treatment are the same as those in the first curing treatment.

[0042] After the second curing process, the copper foil undergoes blackening and ashing treatments. The blackening treatment uses a Zn-containing agent. 2+ 0.2 g / L, Ni 2+ A blackening solution with 1.5 g / L potassium pyrophosphate and 70 g / L potassium pyrophosphate was prepared at 38 °C with an influent flow rate of 8 m³ / L. 3 / h, current density 3 A / dm 2 The solution was treated for 3 seconds under the specified conditions. Subsequently, without drying, it was directly ashed. The ashing solution used contained Zn. 2+ The concentration of Ni is 5 g / L. 2+ The concentration of the active ingredient was 0.1 g / L, and the concentration of potassium pyrophosphate was 100 g / L, and the solution was prepared at 40 °C with an influent flow rate of 8 m³ / L. 3 / h, Current density 8 A / dm 2 Under the condition of processing for 3 seconds.

[0043] After ashing, the copper foil undergoes passivation. The passivation solution used contains 1.0 g / L of hexavalent chromium ions. During the passivation process, the temperature is controlled at 28 ℃, and the influent flow rate is controlled at 4 m³ / L. 3 / h, current density controlled at 15 A / dm 2 The passivation process was carried out for 3 seconds. After the passivation process was completed, the copper foil was washed with water and then coated with 3-glycidyl etheroxypropyltrimethoxysilane as a silane coupling agent at a concentration of 1.8 g / L.

[0044] S3. The copper foil that has undergone all the above surface treatments is thoroughly washed with water and dried in a drying device to finally obtain a high conductivity HVLP copper foil.

[0045] Example 2: A method for preparing a highly conductive HVLP copper foil, which is carried out according to the following steps.

[0046] S1. A copper sulfate electrolyte is injected into an electrolytic cell, using a titanium roller as the cathode and a lead-silver alloy plate as the anode. A direct current is applied to perform electrolytic deposition to prepare the raw foil. In the electrolyte for electrolytic deposition of the raw foil, Cu... 2+ The concentration of the electrolyte was 100 g / L, and the concentration of H2SO4 was 120 g / L. A green foil additive system was added to the electrolyte, with the following amounts of components: hydroxyethyl cellulose 2.0 ppm, gelatin 130 ppm, sodium polydithiopropane sulfonate 68 ppm, polyethylene glycol 30 ppm, and chloride ions 35 ppm. The molecular weight of the gelatin was 15,000 Daltons, and the molecular weight of the polyethylene glycol was 12,000 Daltons. During the electrolysis of the green foil, the electrolyte temperature was controlled at 55 °C, and the current density was controlled at 48,000 A / dm³. 2 Electrolysis for 6 s.

[0047] S2. The above-mentioned electrolytic foil is subjected to a first roughening treatment, a first curing treatment, a second roughening treatment, a second curing treatment, a blackening treatment, an ashing treatment, a passivation treatment, and a silane coupling agent coating treatment in sequence.

[0048] Cu in the first roughening solution 2+ The concentration of the active ingredient was 20 g / L, the concentration of H2SO4 was 200 g / L, and a roughening additive system was added, wherein the amount of the aliphatic sulfonated condensate sulfonated butanone-formaldehyde condensate added was 0.8 ppm, and the amount of the polyether compound polypropylene glycol added was 1.0 ppm. During the roughening process, the temperature was controlled at 30 ℃, and the current density was controlled at 30 A / dm³. 2 The inlet flow rate is controlled at 12 m³ / s. 3 / h, processing time is 6 s.

[0049] After the first roughening treatment, the copper foil undergoes a first curing treatment. The Cu in the first curing solution... 2+ The concentration of the active ingredient was 60 g / L, and the concentration of H2SO4 was 130 g / L. During the curing process, the temperature was controlled at 40 ℃, and the current density was controlled at 25 A / dm³. 2 The inlet flow rate is controlled at 20 m³. 3 / h, processing time is 6 s.

[0050] Cu in the second roughening solution 2+ The concentration of [unspecified ingredient] was 20 g / L, the concentration of H2SO4 was 200 g / L, and a roughening additive system was added, wherein the addition amount of sulfonated methyl ethyl ketone formaldehyde condensate was 0.8 ppm, the addition amount of polypropylene glycol was 1.0 ppm, and the chloride ion concentration was controlled at 40 ppm. During the treatment process, the temperature was controlled at 30 ℃, and the current density was controlled at 12 A / dm³. 2 The inlet flow rate is controlled at 12 m³. 3 / h, processing time is 6 s.

[0051] Repeat the first curing step for the second curing process, then sequentially perform blackening and ashing treatments on the copper foil. The blackening treatment uses a Zn-containing material. 2+ Ni 2+ And the blackening solution of potassium pyrophosphate, in which Zn 2+ The concentration of Ni is 0.4 g / L. 2+ The concentration of the active ingredient was 1.8 g / L, and the concentration of potassium pyrophosphate was 90 g / L; the influent flow rate was controlled at 16 m³ / L at 40 °C. 3 / h, current density is 5 A / dm 2 The process lasts 6 seconds, forming an alloyed blackening layer on the copper foil surface. After the blackening treatment, the foil is directly subjected to ashing without drying. The Zn in the ashing solution...2+ The concentration of Ni is 6 g / L. 2+ The concentration of the active ingredient was 0.5 g / L, and the concentration of potassium pyrophosphate was 130 g / L; the influent flow rate was controlled at 16 m³ / L at 42 ℃. 3 / h, current density is 10 A / dm 2 The blackening layer was stabilized after 6 seconds of processing.

[0052] After ashing, the copper foil undergoes passivation. The concentration of hexavalent chromium ions in the passivation solution is 1.3 g / L. During the passivation process, the temperature is controlled at 30 ℃ and the influent flow rate is controlled at 18 m³ / L. 3 / h, current density controlled at 200 A / dm 2 The treatment time was 6 s. Subsequently, a silane coupling agent coating treatment was performed using 3-glycidyl etheroxypropyltrimethoxysilane at a concentration of 1.8 g / L.

[0053] S3. The copper foil that has undergone all the above surface treatments is thoroughly washed with water and dried in a drying device to obtain a high conductivity HVLP copper foil.

[0054] Example 3: A method for preparing a highly conductive HVLP copper foil, which is carried out according to the following steps.

[0055] S1. A copper sulfate electrolyte is injected into an electrolytic cell, using a titanium roller as the cathode and a lead-silver alloy plate as the anode. A direct current is applied to perform electrolytic deposition to prepare the raw foil. In the electrolyte for electrolytic deposition of the raw foil, Cu... 2+ The concentration of the electrolyte was 92.5 g / L, and the concentration of H2SO4 was 105 g / L. A green foil additive system was added to the electrolyte, with the following amounts of components: hydroxyethyl cellulose 1.25 ppm, gelatin 110 ppm, sodium polydithiopropane sulfonate 54 ppm, polyethylene glycol 20 ppm, and chloride ions 30 ppm; wherein the molecular weight of the gelatin was 12,500 Daltons, and the molecular weight of the polyethylene glycol was 10,000 Daltons. During the electrolysis of the green foil, the electrolyte temperature was controlled at 50 °C, and the current density was controlled at 39,000 A / dm³. 2 The electrolysis time is 4.5s.

[0056] S2. The above-mentioned electrolytic foil is subjected to a first roughening treatment, a first curing treatment, a second roughening treatment, a second curing treatment, a blackening treatment, an ashing treatment, a passivation treatment, and a silane coupling agent coating treatment in sequence.

[0057] The roughening solutions used in both the first and second roughening treatments contain a roughening additive system. This roughening additive system consists of an aliphatic sulfonated condensate, sulfonated cyclohexanone formaldehyde condensate, and a polyether compound, polyethylene glycol methyl ether. The addition amount of both the sulfonated cyclohexanone formaldehyde condensate and the polyethylene glycol methyl ether is 0.5 ppm.

[0058] During the first roughening process, the temperature was controlled at 28 ℃ and the current density was controlled at 22.5 A / dm. 2 The inlet flow rate is controlled at 9 m. 3 / h, processing time is 4.5 s, and Cu in the first roughening solution 2+ The concentration of HCl is 15 g / L, and the concentration of H2SO4 is 175 g / L.

[0059] After the first roughening treatment is completed, the first curing treatment is carried out. During the first curing treatment, the temperature is controlled at 40℃ and the liquid flow rate is controlled at 15 m³ / s. 3 / h, current density controlled at 20 A / dm 2 The processing time was 4.5 seconds, and the Cu in the first curing solution was... 2+ The concentration of HCl was 55 g / L, and the concentration of H2SO4 was 110 g / L.

[0060] The copper foil is then subjected to a second roughening treatment, with the same process conditions as the first roughening treatment, and the chloride ion concentration in the second roughening solution is 25 ppm. After the second roughening treatment, a second curing treatment is performed, with the same process conditions as the first curing treatment.

[0061] After the second curing process is completed, the copper foil is subjected to blackening, ashing, and passivation treatments in sequence.

[0062] In the blackening solution used for blackening treatment, Zn 2+ The concentration was 0.3 g / L, Ni 2+ The concentration of the active ingredient was 1.65 g / L, and the concentration of potassium pyrophosphate was 80 g / L; the temperature was controlled at 38 ℃, and the influent flow rate was controlled at 12 m³ / L. 3 / h, current density controlled at 4 A / dm 2 The processing time is 4.5 seconds.

[0063] After the blackening treatment is completed, the ashing treatment is carried out directly without drying. The Zn in the ashing solution... 2+ The concentration was 5.5 g / L, Ni 2+ The concentration of the active ingredient was 0.3 g / L, and the concentration of potassium pyrophosphate was 115 g / L. During the ashing process, the temperature was controlled at 40 ℃, and the influent flow rate was controlled at 12 m³ / L. 3 / h, current density controlled at 9 A / dm2 The processing time was 4.5 s. Following this, passivation was performed, during which the temperature was controlled at 28 ℃ and the influent flow rate at 11 m³ / s. 3 / h, current density controlled at 107.5A / dm 2 The processing time was 4.5 s, and the concentration of hexavalent chromium ions in the passivation solution was 1.15 g / L.

[0064] S3. The passivated copper foil is coated with a silane coupling agent, specifically 3-glycidyl etheroxypropyltrimethoxysilane, at a concentration of 1.8 g / L. After coating, the copper foil is washed and dried to obtain the high-conductivity HVLP copper foil product.

[0065] Comparative Example 1: A method for preparing a highly conductive HVLP copper foil, comprising the following steps.

[0066] S1. Copper sulfate electrolyte is injected into an electrolytic cell, a titanium roller is used as the cathode and a lead-silver alloy plate is used as the anode, and direct current is applied to perform electrolytic deposition to prepare the original foil. The specific parameters are the same as the preparation steps in Example 3.

[0067] S2. The obtained original foil is subjected to the following treatments in sequence: first roughening treatment, first curing treatment, second roughening treatment, second curing treatment, blackening treatment, ashing treatment, passivation treatment, and silane coupling agent coating treatment.

[0068] The roughening solutions used in the first and second roughening treatments do not contain aliphatic sulfonated condensates or polyether compounds, but only copper salts, sulfuric acid, and conventional conductive salt systems. The remaining process parameters are the same as in Example 3. Specifically, the process parameters for the first roughening treatment are: temperature 28 ℃, current density 22.5 A / dm³. 2 Inlet flow rate 9 m 3 / h, processing time 4.5s; the process parameters for the second roughening treatment are: temperature 28 ℃, current density 10 A / dm 2 Inlet flow rate 9 m 3 / h, processing time 4.5 s.

[0069] The process parameters for the first and second curing treatments are the same as in Example 3, and the Cu in the curing solution is... 2+ The concentration was 55 g / L, the H2SO4 concentration was 110 g / L, and the blackening, ashing, and passivation treatment steps were the same as in Example 3.

[0070] S3. The passivated copper foil was coated with a silane coupling agent, the silane coupling agent being 3-glycidyl etheroxypropyltrimethoxysilane, with a coating concentration of 1.8 g / L; subsequently, the copper foil was washed with water and dried to obtain the comparative HVLP copper foil.

[0071] Comparative Example 2: A method for preparing a highly conductive HVLP copper foil, comprising the following steps.

[0072] S1. Copper sulfate electrolyte is injected into an electrolytic cell, a titanium roller is used as the cathode and a lead-silver alloy plate is used as the anode, and direct current is applied to perform electrolytic deposition to prepare the original foil. The specific parameters are the same as the preparation steps in Example 3.

[0073] S2. The obtained original foil is subjected to the following treatments in sequence: first roughening treatment, first curing treatment, second roughening treatment, second curing treatment, blackening treatment, ashing treatment, passivation treatment, and silane coupling agent coating treatment.

[0074] In the roughening solutions used for the first and second roughening treatments, only sulfonated cyclohexanone formaldehyde condensate was added as a roughening additive; no polyether compounds were added. The amount of sulfonated cyclohexanone formaldehyde condensate added was 0.5 ppm. The remaining basic components and process parameters of the solution remained consistent with those in Example 3. The process parameters for the first roughening treatment were: temperature 28 ℃, current density 22.5 A / dm³. 2 Inlet flow rate 9 m 3 / h, processing time 4.5 s; the process parameters for the second roughening treatment are: temperature 28 ℃, current density 10 A / dm 2 Inlet flow rate 9 m 3 / h, processing time 4.5 s.

[0075] After roughening treatment, the first and second curing treatments are performed sequentially, with Cu in the curing solution. 2+ The concentration of the solvent was 55 g / L, and the concentration of H2SO4 was 110 g / L. The process parameters were the same as in Example 3. After the curing treatment was completed, blackening treatment, ashing treatment and passivation treatment were performed in sequence. The solution composition and process parameters used in each process were the same as in Example 3.

[0076] S3. The passivated copper foil was coated with a silane coupling agent, the silane coupling agent being 3-glycidyl etheroxypropyltrimethoxysilane, with a coating concentration of 1.8 g / L; subsequently, the copper foil was washed with water and dried to obtain the HVLP copper foil of Comparative Example 2.

[0077] Performance testing

[0078] The surface profile, peel strength, conductivity and microstructure of the copper foil samples of Examples 1-3 and Comparative Examples 1-2 were tested according to national standards and industry-standard testing methods.

[0079] Surface profile test: The surface profile of the copper foil was tested using a three-dimensional white light interferometer. The arithmetic mean roughness Ra and the maximum profile height Rz were determined in accordance with GB / T 1031-2009 "Product Geometric Technical Specification Surface Structure Profile Method".

[0080] Peel strength test: Each copper foil sample was pressed with an epoxy fiberglass substrate and the peel strength was tested according to IPC-TM-650 2.4.8 "Peel Strength Test Method".

[0081] Conductivity test: The volume resistivity of the copper foil of each sample was tested using the four-probe method, and the test method was in accordance with GB / T 3048.2-2007 "Electrical Performance Test Methods for Wires and Cables - Resistivity Test".

[0082] Microstructure characterization: The surface and cross-sectional microstructure of the copper foil samples were observed using scanning electron microscopy (SEM).

[0083] The performance test results are shown in Table 1 below.

[0084] Table 1 Sample performance analysis results

[0085]

[0086] As shown in Table 1, Examples 1-3 are significantly superior to the comparative samples in terms of surface profile and conductivity. Regarding surface profile, the Ra values ​​of Examples 1-3 are all below 0.20 μm, and the Rz value gradually decreases from 1.45 μm to 1.08 μm, significantly smaller than Comparative Examples 1 and 2. This indicates that the present invention can effectively refine the copper nodule size and reduce surface roughness, which is beneficial for meeting the requirements of high-frequency, high-speed circuit boards for low-profile copper foil. In terms of conductivity, the volume resistivity of the copper foil in the examples is all below 1.80 μΩ·cm, and Example 3 reaches 1.75 μΩ·cm, superior to the comparative samples. This shows that the fine and uniform dense copper nodule structure helps reduce grain boundary scattering and improve electron transport efficiency. In contrast, although the comparative samples have higher peel strength, their copper nodule size is larger and the structure is uneven, which is detrimental to high-frequency signal transmission.

[0087] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0088] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A method for preparing a highly conductive HVLP copper foil, characterized in that, Includes the following steps: S1. Electrolytic foil electrolyte is injected into an electrolytic cell, with a titanium roller as the cathode and a lead-silver alloy plate as the anode. Direct current is applied to perform electrolytic deposition to obtain the original foil. The electrolyte for the electrolytic foil contains a foil additive system, which is composed of hydroxyethyl cellulose, gelatin, sodium polydithiopropane sulfonate, polyethylene glycol, and chloride ions. S2. The original foil is subjected to a first roughening treatment, a first curing treatment, a second roughening treatment, a second curing treatment, a blackening treatment, an ashing treatment, a passivation treatment, and a silane coupling agent coating treatment in sequence. The roughening liquid used in the first and second roughening treatments contains a roughening additive system, which is composed of aliphatic sulfonated condensates and polyether compounds. S3. The copper foil coated with the silane coupling agent is washed and dried to obtain a highly conductive HVLP copper foil. In step S2, the amounts of each component in the roughening additive system added to the roughening solution used in the first and second roughening treatments are: 0.2-0.8 ppm for aliphatic sulfonated condensate and 0.2-1.0 ppm for polyether compounds; and the chloride ion concentration in the roughening solution used in the second roughening treatment is 10-40 ppm. The aliphatic sulfonated condensate is selected from one or more of sulfonated acetone formaldehyde condensate, sulfonated butanone formaldehyde condensate, and sulfonated cyclohexanone formaldehyde condensate, and its molecular weight is 2000~10000 Daltons. The polyether compound is selected from one or more of polyethylene glycol, polypropylene glycol, polyethylene glycol methyl ether, polyoxyethylene polyoxypropylene, polyoxyethylene alkyl ether, and polyethylene oxide, and its molecular weight is 6,000 to 10,000 Daltons.

2. The preparation method according to claim 1, characterized in that, The addition amounts of each component in the raw foil additive system described in step S1 are as follows: hydroxyethyl cellulose 0.5~2.0ppm, gelatin 90~130ppm, sodium polydithiopropane sulfonate 40~68ppm, polyethylene glycol 10~30ppm, and chloride ions 25~35ppm.

3. The preparation method according to claim 1, characterized in that, The gelatin in step S1 has a molecular weight of 10,000 to 15,000 Daltons, and the polyethylene glycol has a molecular weight of 8,000 to 12,000 Daltons.

4. The preparation method according to claim 1, characterized in that, Cu in the electrolyte of the electrolytic green foil in step S1 2 + The concentration of H2SO4 is 85~100 g / L, and the concentration of H2SO4 is 90~120 g / L; the process parameters for the electrolytic foil production step are: electrolyte temperature 50±5℃, current density 30000~48000 A / dm³. 2 Electrolysis time: 3-6 seconds.

5. The preparation method according to claim 1, characterized in that, In step S2, the process parameters for the first roughening treatment and the second roughening treatment are as follows: The process parameters for the first roughening treatment are: temperature 28±2 ℃, current density 15~30 A / dm. 2 Inlet flow rate: 6–12 m³ 3 / h, processing time 3-6 s, and Cu in the first roughening solution 2+ The concentration of [unspecified substance] is 10–20 g / L, and the concentration of H2SO4 is 150–200 g / L; The process parameters for the second roughening treatment are: temperature 28±2 ℃, current density 8~12 A / dm. 2 Inlet flow rate: 6–12 m³ 3 / h, processing time 3-6 s, and Cu in the second roughening solution 2+ The concentration of the substance is 10–20 g / L, and the concentration of H2SO4 is 150–200 g / L.

6. The preparation method according to claim 1, characterized in that, In step S2, the process parameters for the first curing treatment and the second curing treatment are as follows: The process parameters for the first curing treatment are: temperature 40±5 ℃, liquid flow rate 10~20 m³ / h. 3 / h, current density 15~25 A / dm 2 The processing time is 3-6 seconds, and the Cu in the first curing solution... 2+ The concentration of [unspecified substance] is 50–60 g / L, and the concentration of H2SO4 is 90–130 g / L; The process parameters for the second curing treatment are: temperature 40±5 ℃, liquid flow rate 10~20 m³ / h. 3 / h, current density 15~20 A / dm 2 The processing time is 3-6 seconds, and the Cu in the second curing solution... 2+ The concentration of HCl is 50–60 g / L, and the concentration of H2SO4 is 90–130 g / L.

7. The preparation method according to claim 1, characterized in that, In step S2, the process parameters for the blackening treatment and the ashing treatment are as follows: The process parameters for the blackening treatment are: temperature 38±2 ℃, liquid flow rate 8~16 m³ / s. 3 / h, current density 3~5 A / dm 2 Processing time: 3-6 seconds; The process parameters for the ashing treatment are: temperature 40±2 ℃, liquid flow rate 8~16 m³ / s. 3 / h, current density 8~10 A / dm 2 Processing time: 3-6 seconds.

8. The preparation method according to claim 1, characterized in that, In step S2, the passivation process parameters are: temperature 28±2 ℃, and influent flow rate 4~18 m³ / s. 3 / h, current density 15~200 A / dm 2 The processing time is 3–6 s, and the concentration of hexavalent chromium ions in the passivation solution is 1.0–1.3 g / L; The silane coupling agent used in the silane coupling agent coating treatment is 3-glycidyl etheroxypropyltrimethoxysilane, and its coating concentration is 1.8 g / L.

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