Ultra-low profile high peel copper foil, method of making and use thereof

Abstract

This invention relates to the field of electrolytic aluminum foil for communication applications, and discloses an ultra-low profile, high peel strength copper foil, its preparation method, and its application. A method for preparing copper foil includes the following steps: (1) electrodepositing an electroplating solution to obtain a raw copper foil; (2) placing the raw copper foil into a micro-roughening solution for micro-roughening to obtain a micro-roughened copper foil; (3) placing the micro-roughened copper foil into a curing solution for curing to obtain a cured copper foil; wherein, on the surface of the micro-roughened copper foil, 10-20 spherical copper nodules are distributed per square micrometer; the average spacing between adjacent spherical copper nodules is 10-20 nm; the spherical copper nodules include small spherical copper nodules and large spherical copper nodules, the average diameter of the small spherical copper nodules is 150-250 nm, and the average diameter of the large spherical copper nodules is 260-500 nm. The copper foil provided by this invention has ultra-low profile and high peel strength.

Description

Technical Field

[0001] This invention relates to the field of electrolytic copper foil for communication, and specifically to an ultra-low profile high peeling copper foil, its preparation method, and its application. Background Technology

[0002] 5G communication offers significant improvements over 4G communication in terms of transmission speed and data latency. It requires the use of high-frequency communication bands of 3.5GHz to 30GHz. As the signal frequency increases, the "skin effect" generated by the high-frequency signal on the surface of the raw copper foil used to transmit 5G signals becomes more and more significant, which reduces the integrity of the transmitted signal and leads to an increase in the bit error rate.

[0003] With the increasing demand for high-frequency signal transmission in 5G communication and high-performance electronic products, the use of copper foil on copper clad laminates (CCLs) and printed circuit boards (PCBs) requires low profile (high density and low surface roughness) and high peel strength to reduce signal loss caused by the "skin effect." However, as surface roughness decreases, the adhesion between the copper foil and the substrate also decreases. Therefore, how to prepare a copper foil with ultra-low profile and high peel strength is an urgent problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems existing in the prior art and provide an ultra-low profile, high peel strength copper foil, its preparation method, and its applications. The copper foil provided by this invention has ultra-low profile and high peel strength.

[0005] To achieve the above objectives, the present invention provides a method for preparing copper foil, the method comprising the following steps:

[0006] (1) Electrodeposition is performed on the electroplating solution to obtain raw copper foil;

[0007] (2) The raw copper foil is placed in a coarsening solution for coarsening to obtain coarsened copper foil;

[0008] (3) The micro-coarsened copper foil is placed in a curing solution for curing to obtain the copper foil;

[0009] Among them, on the surface of the micro-coarsened copper foil, there are 10-20 spherical copper nodules per square micrometer of copper foil; the average spacing between adjacent spherical copper nodules is 10-20 nm.

[0010] The spherical copper abscesses include small spherical copper abscesses and large spherical copper abscesses. The average diameter of the small spherical copper abscesses is 150-250 nm, and the average diameter of the large spherical copper abscesses is 260-500 nm.

[0011] Preferably, the electroplating solution comprises 65-150 g / L sulfuric acid, 60-100 g / L copper sulfate (calculated as copper ions), 10-30 ppm chloride ions, and 5-25 mg / L mercapto compounds, 5-20 mg / L amine organics, and 5-10 mg / L polyether organics.

[0012] Preferably, the micro-coarsening solution comprises copper sulfate at a concentration of 10-40 g / L based on copper ions, sulfuric acid at a concentration of 80-200 g / L, vanadate at a concentration of 0.01-0.15 g / L, rare earth nitrate at a concentration of 0.1-0.5 g / L, stannous salt at a concentration of 0.1-1.5 g / L, and / or rare earth chloride at a concentration of 1-3 mg / L.

[0013] Preferably, the curing solution comprises copper sulfate with a content of 40-70 g / L based on copper ions, sulfuric acid with a content of 70-100 g / L, rare earth sulfate with a content of 1-5 g / L, and sodium dodecyl sulfate with a content of 0.5-2 g / L.

[0014] A second aspect of the present invention provides a copper foil prepared by the method described in the first aspect.

[0015] The third aspect of this invention provides an application of the copper foil described in the second aspect in 5G communication.

[0016] The beneficial effects of the present invention through the above technical solution include:

[0017] The method for preparing ultra-low profile, high peel strength copper foil provided by this invention employs specific electrodeposition-micro-roughening-curing steps. Simultaneously, the micro-roughened copper foil surface exhibits a specific distribution and particle size of nanoscale spherical copper nodules, with an average spacing of only 10-20 nm between adjacent spherical nodules. This increases the rough surface area of ​​the copper foil, giving it ultra-low profile characteristics and high surface roughness. It also reduces the "skin effect" of the copper foil, increases the adhesion between the copper foil and the substrate, and ensures that the resulting copper foil simultaneously meets the requirements of low profile and high peel strength, satisfying the application requirements of copper foil in high-frequency and high-speed applications.

[0018] The method for preparing ultra-low profile high peeling copper foil provided by this invention is simple to operate, low in cost, and suitable for industrial application. Attached Figure Description

[0019] Figure 1 This is a scanning electron microscope image of the raw copper foil obtained by electrodeposition in Example 1 of the present invention;

[0020] Figure 2 This is a scanning electron microscope image of the copper foil prepared in Example 1 of the present invention;

[0021] Figure 3 This is a scanning electron microscope image of the raw copper foil obtained by electrodeposition in Example 3 of the present invention;

[0022] Figure 4 This is a scanning electron microscope image of the copper foil prepared in Example 3 of the present invention. Detailed Implementation

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0024] This invention provides a method for preparing copper foil, the method comprising the following steps:

[0025] (1) Electrodeposition is performed on the electroplating solution to obtain raw copper foil;

[0026] (2) The raw copper foil is placed in a coarsening solution for coarsening to obtain coarsened copper foil;

[0027] (3) The micro-coarsened copper foil is placed in a curing solution for curing to obtain the copper foil;

[0028] Among them, on the surface of the micro-coarsened copper foil, there are 10-20 spherical copper nodules per square micrometer of copper foil; the average spacing between adjacent spherical copper nodules is 10-20 nm.

[0029] The spherical copper abscesses include small spherical copper abscesses and large spherical copper abscesses. The average diameter of the small spherical copper abscesses is 150-250 nm, and the average diameter of the large spherical copper abscesses is 260-500 nm.

[0030] According to the present invention, preferably, 15-20 spherical copper nodules are distributed per square micrometer on the surface of the micro-roughened copper foil. This preferred embodiment can form uniformly distributed spherical copper nodules on the surface of the micro-roughened copper foil, which is beneficial for increasing the rough surface area of ​​the copper foil, giving it an ultra-low profile, improving surface roughness, reducing the "skin effect" of the copper foil, and increasing the adhesion between the copper foil and the substrate.

[0031] The distribution of the spherical copper nodules on the surface of the micro-coarsened copper foil described in this invention was determined by scanning electron microscopy.

[0032] The present invention does not impose any particular limitation on the number of small spherical copper nodules or large spherical copper nodules distributed per square micrometer of copper foil, as long as the total number of copper nodules distributed per square micrometer of copper foil is satisfied.

[0033] According to the present invention, preferably, the average spacing between adjacent spherical copper nodules is 10-15 nm.

[0034] In this invention, the distance between adjacent spherical copper nodules refers to the shortest distance between the edges of adjacent spherical copper nodules.

[0035] The distance between adjacent spherical copper nodules described in this invention was measured using a scanning electron microscope.

[0036] According to the present invention, preferably, the average diameter of the small spherical copper nodules is 150-230 nm, and the average diameter of the large spherical copper nodules is 260-460 nm.

[0037] The diameter of the spherical copper nodule described in this invention was measured using a scanning electron microscope.

[0038] According to the present invention, preferably, the average diameter ratio of the small spherical copper nodules to the large spherical copper nodules is 1.1-2.5, more preferably 1.5-2.

[0039] To obtain copper foil with ultra-low profile and high peel strength, the electroplating solution preferably includes 65-150 g / L sulfuric acid, 60-100 g / L copper sulfate (based on copper ions), 10-30 ppm chloride ions, and at least one of 5-25 mg / L mercapto compound, 5-20 mg / L amine organic compound, and 5-10 mg / L polyether organic compound.

[0040] In this invention, the sulfuric acid is 65-150 g / L, for example 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L, 125 g / L, 130 g / L, 135 g / L, 140 g / L, 145 g / L, 150 g / L, and any value within the range formed by any two of these values.

[0041] In this invention, the copper sulfate content, calculated as copper ions, is 60-100 g / L, for example, 60 g / L, 65 g / L, 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, and any value within the range formed by any two of these values.

[0042] In this invention, chloride ions are 10-30 ppm, for example 10 ppm, 12 ppm, 14 ppm, 16 ppm, 18 ppm, 20 ppm, 22 ppm, 24 ppm, 26 ppm, 28 ppm, 30 ppm, and any value within the range formed by any two of these values.

[0043] In this invention, ppm refers to mass concentration.

[0044] In this invention, the substance providing chloride ions is not particularly limited and can be a chloride commonly used in the art. Hydrochloric acid is used as an example in this embodiment.

[0045] In this invention, the thiol compound is 5-25 mg / L, for example 5 mg / L, 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L, 10 mg / L, 11 mg / L, 12 mg / L, 13 mg / L, 14 mg / L, 15 mg / L, 16 mg / L, 17 mg / L, 18 mg / L, 19 mg / L, 20 mg / L, 21 mg / L, 22 mg / L, 23 mg / L, 24 mg / L, 25 mg / L, and any value within the range formed by any two of these values.

[0046] In this invention, the amine organic compound is 5-20 mg / L, for example 5 mg / L, 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L, 10 mg / L, 11 mg / L, 12 mg / L, 13 mg / L, 14 mg / L, 15 mg / L, 16 mg / L, 17 mg / L, 18 mg / L, 19 mg / L, 20 mg / L, and any value within any range formed by any two of these values.

[0047] In this invention, the polyether organic compound is 5-10 mg / L, for example 5 mg / L, 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L, 10 mg / L, and any value within the range formed by any two of these values.

[0048] Preferably, the electroplating solution comprises 65-150 g / L sulfuric acid, 60-100 g / L copper sulfate (calculated as copper ions), 10-30 ppm chloride ions, and at least two of the following: 5-25 mg / L mercapto compound, 5-20 mg / L amine organic compound, and 5-10 mg / L polyether organic compound.

[0049] Most preferably, the electroplating solution comprises 65-150 g / L sulfuric acid, 60-100 g / L copper sulfate (based on copper ions), 10-30 ppm chloride ions, and 5-25 mg / L mercapto compounds, 5-20 mg / L amine organics, and 5-10 mg / L polyether organics. This preferred embodiment is more conducive to producing a raw foil with a stable roughness ≤0.9 μm, and the electroplating solution is stable and less prone to deterioration.

[0050] The present invention allows for a wide range of selections of the thiol compounds, which can be conventional choices in the art. Preferably, the thiol compound is selected from at least one of mercaptoethanol, 2-mercapto-1-methylimidazolium, 4-mercaptobenzenesulfonic acid, sodium 3-mercapto-1-propanesulfonate, and 2-mercaptopyridine.

[0051] The present invention allows for a wide range of selections of the amine compounds, which can be conventional choices in the art. Preferably, the amine organic compound is selected from at least one of polyacrylamide, bone glue, gelatin, collagen, triisopropanolamine, and polyethyleneimine.

[0052] According to the present invention, preferably, the polyether organic compound is selected from at least one of polyoxyethylene alkyl ethers, polyethylene glycol, and poly-2-ethyl-2-oxazoline. All of the above substances are commercially available.

[0053] This invention does not impose any particular requirements on the molecular weight of the polyether organic compounds, and such requirements are not specified herein.

[0054] According to the present invention, preferably, the surface roughness Rz of the raw copper foil is ≤0.9μm, more preferably 0.8-0.9μm. This preferred embodiment facilitates obtaining copper foil with low surface roughness, allowing for the deposition of copper nodules on a smooth surface during subsequent roughening treatment, and improving the uniformity of the roughening effect.

[0055] This invention does not particularly limit the operating conditions for electrodeposition, as long as a raw copper foil meeting the aforementioned surface roughness is obtained. Preferably, the operating conditions for electrodeposition include: a current density of 15-35 A / dm². 2 Preferably 20-30 A / dm 2 The temperature of the electroplating solution is 15-50℃, preferably 25-45℃; the circulation flow rate of the electroplating solution is 180-360L / min, preferably 200-350L / min.

[0056] In this invention, the electroplating solution is provided in a circulating manner to help eliminate concentration polarization, thereby obtaining a copper foil with low roughness.

[0057] The present invention does not particularly limit the method of realizing the circulation of the electroplating solution, and can use commonly used technical means in the field. For example, the present invention uses a bubbling device to achieve a corresponding circulation rate of the electroplating solution.

[0058] According to the present invention, preferably, in the electrodeposition step (1), the surface roughness Rz of the cathode plate is ≤2μm. Using this preferred embodiment, electrodeposition on a relatively smooth cathode plate can yield a raw copper foil with the aforementioned surface roughness.

[0059] The present invention does not particularly limit the method of obtaining the cathode plate with the above-mentioned surface roughness, and can use the technical means commonly used in the field. The present invention does not limit it here.

[0060] The present invention allows for a wide range of choices for the types of cathode and anode plates, which can be conventional choices in the field. Preferably, in the electrodeposition step (1), an iridium-plated plate is used as the anode plate and a pure titanium plate is used as the cathode plate.

[0061] The iridium-plated plate described in this invention refers to an iridium-plated titanium plate. Both the iridium-plated plate and the pure titanium plate are commercially available.

[0062] The micro-coarsening solution described in this invention facilitates the formation of dense, uniform, and regularly shaped spherical copper nodule particles on the surface of raw copper foil. Furthermore, the micro-coarsening solution is stable and does not deteriorate, allowing for repeated use. Preferably, the micro-coarsening solution comprises copper sulfate (10-40 g / L based on copper ions), sulfuric acid (80-200 g / L), vanadate (0.01-0.15 g / L), rare earth nitrate (0.1-0.5 g / L), stannous salt (0.1-1.5 g / L), and / or rare earth chloride (1-3 mg / L).

[0063] In this invention, the copper sulfate content, calculated as copper ions, is 10-40 g / L, for example 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, and any value within the range formed by any two of these values.

[0064] In this invention, the sulfuric acid concentration is 80-200 g / L, for example, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, 105 g / L, 110 g / L, 115 g / L, 120 g / L, 125 g / L, 130 g / L, 135 g / L, 140 g / L, 145 g / L, 150 g / L, 155 g / L, 160 g / L, 165 g / L, 170 g / L, 175 g / L, 180 g / L, 185 g / L, 190 g / L, 195 g / L, 200 g / L, and any value within the range formed by any two of these values.

[0065] In this invention, the stannous salt is 0.1-1.5 g / L, for example 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, 1.5 g / L, and any value within any range formed by any two of these values.

[0066] In this invention, the vanadate is 0.01-0.15 g / L, for example 0.01 g / L, 0.02 g / L, 0.03 g / L, 0.04 g / L, 0.05 g / L, 0.06 g / L, 0.07 g / L, 0.08 g / L, 0.09 g / L, 0.1 g / L, 0.11 g / L, 0.12 g / L, 0.13 g / L, 0.14 g / L, 0.15 g / L, and any value within any range formed by any two of these values.

[0067] In this invention, the rare earth nitrate is 0.1-0.5 g / L, for example 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, and any value within the range formed by any two of these values.

[0068] In this invention, the rare earth chloride is 1-3 mg / L, for example 1 mg / L, 1.5 mg / L, 2 mg / L, 2.5 mg / L, 3 mg / L, and any value within the range formed by any two of these values.

[0069] More preferably, the micro-coarsening solution comprises copper sulfate at a concentration of 10-40 g / L based on copper ions, sulfuric acid at a concentration of 80-200 g / L, vanadate at a concentration of 0.01-0.15 g / L, rare earth nitrate at a concentration of 0.1-0.5 g / L, stannous salt at a concentration of 0.1-1.5 g / L, and rare earth chloride at a concentration of 1-3 mg / L.

[0070] The present invention allows for a wide range of vanadate types, and can include various vanadates conventionally used in the art. Preferably, the vanadate is selected from at least one of sodium vanadate, potassium vanadate, and iron vanadate.

[0071] The present invention allows for a wide range of choices regarding the types of stannous salts, and can include various stannous salts conventionally used in the art. Preferably, the stannous salt is stannous sulfate.

[0072] The present invention allows for a wide range of choices of rare earth nitrates, which can be various rare earth nitrates commonly used in the art. Preferably, the rare earth nitrate is selected from at least one of cerium nitrate, lanthanum nitrate, and terbium nitrate.

[0073] The present invention allows for a wide range of choices of rare earth chlorides, which can be various rare earth chlorides conventionally used in the art. Preferably, the rare earth chloride is lanthanum chloride and / or yttrium chloride.

[0074] According to the present invention, preferably, the operating conditions for the micro-coarsening include: a current density of 10-35 A / dm. 2 Preferably 15-30 A / dm 2The temperature for preparing the micro-coarsening solution is 10-40℃, preferably 15-35℃; the circulation flow rate of the micro-coarsening solution is 100-250L / min, preferably 100-200L / min; and the micro-coarsening treatment time is 2-10s, preferably 3-8s.

[0075] In this invention, the micro-coarsening solution is provided by circulating flow to help eliminate concentration polarization, thereby obtaining a copper foil with low roughness.

[0076] The present invention does not particularly limit the implementation method of the micro-coarsened solution circulation flow, and can use commonly used technical means in the field. For example, the present invention uses a bubbling device to achieve the corresponding circulation flow rate of the micro-coarsened solution.

[0077] According to the present invention, preferably, the thickness of the micro-roughening layer of the micro-roughened copper foil is 0.2-0.8 μm, more preferably 0.2-0.5 μm, wherein the thickness of the micro-roughening layer is the thickness of the micro-roughening layer attached to the surface of the raw copper foil after micro-roughening treatment.

[0078] The thickness of the micro-roughened layer of the micro-roughened copper foil described in this invention was determined by scanning electron microscopy.

[0079] According to the present invention, preferably, the mass per unit area of ​​the micro-coated copper foil increases by 2-8 g / m² compared to the raw copper foil. 2 Preferred addition of 3-6g / m 2 .

[0080] According to the present invention, preferably, the surface roughness Rz of the micro-coated copper foil increases by 0.1-0.7 μm, more preferably by 0.1-0.5 μm, relative to the raw copper foil.

[0081] In this invention, the roughening layer of the micro-roughened copper foil after roughening treatment is particularly thin, so that the increase in unit area mass and surface roughness of the micro-roughened copper foil is less than that of raw copper foil, which is beneficial to producing copper foil with both low profile and high peel strength.

[0082] In the curing process of this invention, a dense layer of metallic copper is deposited in the gaps between the spherical copper nodules of the copper foil layer, which effectively increases the contact area between the copper foil and the substrate and reduces the surface roughness of the copper foil.

[0083] The curing solution described in this invention facilitates the deposition of a stable and smooth copper film on the surface of the roughened layer, reduces surface roughness to a certain extent, and fixes the roughened layer to prevent powder shedding. Simultaneously, the curing solution is stable and does not deteriorate, allowing for recycling. Preferably, the curing solution comprises copper sulfate with a copper ion content of 40-70 g / L, sulfuric acid of 70-100 g / L, rare earth sulfates of 1-5 g / L, and / or sodium dodecyl sulfate of 0.5-2 g / L.

[0084] More preferably, the curing solution comprises copper sulfate with a content of 40-70 g / L (based on copper ions), sulfuric acid with a content of 70-100 g / L, rare earth sulfate with a content of 1-5 g / L, and sodium dodecyl sulfate with a content of 0.5-2 g / L.

[0085] In this invention, the copper sulfate content, calculated as copper ions, is 40-70 g / L, for example 40 g / L, 45 g / L, 50 g / L, 55 g / L, 60 g / L, 65 g / L, 70 g / L, and any value within the range formed by any two of these values.

[0086] In this invention, the sulfuric acid is 70-100 g / L, for example 70 g / L, 75 g / L, 80 g / L, 85 g / L, 90 g / L, 95 g / L, 100 g / L, and any value within the range formed by any two of these values.

[0087] In this invention, the rare earth sulfate is 1-5 g / L, for example 1 g / L, 1.5 g / L, 2 g / L, 2.5 g / L, 3 g / L, 3.5 g / L, 4 g / L, 4.5 g / L, 5 g / L, and any value within the range formed by any two of these values.

[0088] In this invention, sodium dodecyl sulfonate is 0.5-2 g / L, for example 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L, 1.5 g / L, 1.6 g / L, 1.7 g / L, 1.8 g / L, 1.9 g / L, 2 g / L, and any value within any range formed by any two of these values.

[0089] The present invention allows for a wide range of choices of rare earth sulfates, which can be various rare earth sulfates commonly used in the art. Preferably, the rare earth sulfate is selected from at least one of lanthanum sulfate, cerium sulfate, and terbium sulfate.

[0090] According to the present invention, preferably, the curing operating conditions include: a current density of 20-40 A / dm³. 2 Preferably 20-30 A / dm 2 The curing solution temperature is 10-40℃, preferably 15-35℃; the curing solution circulation flow rate is 100-250L / min, preferably 100-200L / min; the curing time is 3-10s, preferably 5-10s.

[0091] In this invention, the curing solution is provided in a circulating flow manner, which is beneficial to eliminating concentration polarization, thereby obtaining a copper foil with low roughness.

[0092] This invention does not particularly limit the method of realizing the circulation of the solidified solution; it can be carried out using techniques commonly used in the field. For example, this invention uses a bubbling device to achieve the corresponding circulation rate of the solidified solution.

[0093] According to the present invention, preferably, the method further includes: placing the cured copper foil into an alloying solution for alloying treatment to obtain alloyed copper foil. This preferred embodiment can improve the surface stability of the copper foil at high temperatures.

[0094] According to the present invention, preferably, the alloying operating conditions include: a current density of 1-15 A / dm. 2 Preferably 2-11 A / dm 2 The alloying solution temperature is 10-35℃, preferably 15-25℃; the alloying treatment time is 3-25s, preferably 5-20s.

[0095] According to the present invention, preferably, the alloying solution comprises 1-100 g / L of alloy source and 3-130 g / L of complexing agent.

[0096] According to the present invention, preferably, the alloy source is a soluble metal salt, and more preferably selected from at least one of nickel salt, tungsten salt, zirconium salt, hafnium salt, cobalt salt, molybdenum salt, bismuth salt and rare earth salt.

[0097] According to the present invention, more preferably, the alloy source is selected from at least one of nickel sulfate, sodium tungstate, zirconium sulfate, hafnium sulfate, cobalt sulfate, sodium molybdate, cerium sulfate, bismuth sulfate, lanthanum sulfate, praseodymium sulfate, and dysprosium sulfate, and more preferably from at least one of nickel sulfate, bismuth sulfate, and lanthanum sulfate.

[0098] According to the present invention, preferably, the alloying solution comprises at least one of 10-62 g / L bismuth sulfate, 10-28 g / L nickel sulfate and 1-3 g / L lanthanum sulfate.

[0099] According to the present invention, preferably, the complexing agent is selected from at least one of citric acid, glycine and triethanolamine.

[0100] According to the present invention, preferably, the alloying solution comprises at least one selected from 14-87 g / L citric acid, 5-20 g / L glycine and 3-15 g / L triethanolamine.

[0101] Most preferably, the alloying solution comprises 10-62 g / L bismuth sulfate, 10-28 g / L nickel sulfate, 1-3 g / L lanthanum sulfate, 14-87 g / L citric acid, 5-20 g / L glycine and 3-15 g / L triethanolamine.

[0102] According to the present invention, preferably, the method further includes: placing the alloyed copper foil into a silanization solution for silanization treatment to obtain the copper foil. This preferred embodiment can improve the oxidation resistance of the copper foil.

[0103] According to the present invention, preferably, the silanization operation time is 3-10 seconds.

[0104] According to the present invention, preferably, the silanization solution includes a silane coupling agent and a pH adjuster, the pH value of the silanization solution is 5-7, and the concentration of the silanization solution is 1-3 mol / L.

[0105] This invention allows for a wide range of pH adjusters, including various acids commonly found in the art. The pH adjuster can be an organic acid or an inorganic acid. Acetic acid is used as an example in this embodiment.

[0106] According to the present invention, preferably, the silane coupling agent is selected from at least one of KH550 silane coupling agent, KH560 silane coupling agent, KH570 silane coupling agent and KH590 silane coupling agent.

[0107] Preferably, the method further includes: drying the silanized copper foil to obtain the copper foil.

[0108] The present invention does not particularly limit the drying method, and can use the techniques commonly used in the field.

[0109] The present invention does not impose any particular limitation on the specific drying conditions, which can be appropriately selected according to the specific circumstances, as long as the purpose of removing moisture from the surface of the copper foil can be achieved.

[0110] According to the present invention, preferably, the method further includes: performing a passivation treatment before silanizing the alloyed copper foil. This preferred embodiment effectively prevents the copper foil from oxidizing or corroding.

[0111] According to the present invention, preferably, the passivation operating conditions include a current density of 10-20 A / dm. 2 The passivation solution temperature is 15-25℃; the passivation treatment time is 10-20s.

[0112] According to the present invention, preferably, the passivation solution comprises at least one selected from 2-6 g / L chromium oxide, 6-30 g / L sodium hydroxide, 2-15 g / L sodium saccharin and 4-12 g / L ethylenediamine.

[0113] According to the present invention, more preferably, the passivation solution comprises 2-6 g / L chromium oxide, 6-30 g / L sodium hydroxide, 2-15 g / L sodium saccharin and 4-12 g / L ethylenediamine.

[0114] The present invention does not impose any particular limitation on the preparation method of the solution used in the above steps, and the solution can be prepared in accordance with conventional methods.

[0115] In the above steps of this invention, the preparation of the solution can be carried out by ultrasound or stirring to achieve uniform mixing and accelerate dissolution. This invention does not require such methods.

[0116] A second aspect of the present invention provides a copper foil prepared by the method described in the first aspect.

[0117] According to the present invention, preferably, the surface roughness Ra of the copper foil is ≤0.2μm, more preferably 0.1-0.2μm; and the surface roughness Rz is ≤1μm, more preferably 0.8-1μm.

[0118] The surface roughness Ra and Rz of the copper foil described in this invention were measured by a roughness tester according to the GBT5230-2020 standard.

[0119] According to the present invention, preferably, the surface contact angle of the copper foil is 75-105°, more preferably 80-95°.

[0120] The surface contact angle of the copper foil described in this invention is measured by a fully automatic contact angle measuring instrument.

[0121] The surface roughness and surface contact angle of the copper foil described in this invention are within the above-mentioned range, which makes the copper foil have good affinity with the substrate and effectively enhances the bonding force between the copper foil and the substrate.

[0122] The copper foil of the present invention has high peel strength. Preferably, the peel strength of the copper foil on the PPO substrate at 150-200℃ is ≥0.6N / mm, more preferably 0.6-1N / mm; and the peel strength on the FR-4 substrate at 150-170℃ is ≥1.1N / mm, more preferably 1.2-1.8N / mm.

[0123] The method for determining the peel strength of copper foil on PPO substrate at 150-200℃ according to the present invention is as follows: copper foil and PPO resin are placed in a press machine and pressed at 150-200℃ and 10MPa for 4 hours. After pressing, it is etched with 30wt% ferric chloride at 50℃ for 20 minutes, and then the peel strength is tested by a peel tester.

[0124] The method for determining the peel strength of copper foil on FR-4 substrate at 150-170℃ according to the present invention is as follows: copper foil and FR-4 resin are placed in a press machine and pressed at 150-170℃ and 10MPa for 4 hours. After pressing, it is etched with 30wt% ferric chloride at 50℃ for 20 minutes, and then the peel strength is tested using a peel tester.

[0125] According to the present invention, preferably, the surface area ratio of the copper foil is 1-2, more preferably 1.4-1.9, wherein the surface area ratio of the copper foil is the ratio of the outline surface area to the planar area of ​​the copper foil.

[0126] The surface area ratio of the copper foil described in this invention is within the above-mentioned range, which effectively ensures that the copper foil has a larger surface area, a larger surface roughness, and low profile to reduce the "skin effect".

[0127] The surface area ratio of the copper foil described in this invention was measured using a 3D laser confocal microscope.

[0128] According to the present invention, preferably, the unit area mass of the copper foil is 100-200 g / m². 2 The preferred value is 150-170 g / m³. 2 .

[0129] The copper foil of the present invention has a unit square meter mass within the above-mentioned range, which ensures that the copper foil has a low profile while reducing the amount of copper used, making it more economical.

[0130] The mass per square meter of the copper foil described in this invention was measured using an analytical balance.

[0131] The copper foil described in this invention meets the requirements for use in 5G high-frequency applications. According to this invention, preferably, the signal loss of the copper foil at a frequency of 12.5 GHz is 1-3 dB / m; more preferably, it is 1.4-2 dB / m.

[0132] Among them, 5G high frequency refers to the frequency band with an operating frequency of 6GHz or higher. The copper foil provided in this invention is an ultra-low profile high peel strength copper foil, which has the advantages of low surface roughness, ultra-low profile and strong peel resistance, and can meet the requirements of 5G high frequency applications and can be used in 5G high frequency communication.

[0133] The signal loss of the copper foil described in this invention at a frequency of 12.5 GHz was measured by a fully automatic dielectric loss meter.

[0134] The third aspect of this invention provides an application of the copper foil described in the second aspect in 5G communication.

[0135] The present invention will be described in detail below through embodiments.

[0136] In the following embodiments, the methods for measuring parameters such as the surface roughness Ra and Rz of the copper foil, the peel strength of the PPO substrate, the peel strength of the FR-4 substrate, the mass per unit area, and the signal loss at a frequency of 12.5 GHz are as described above.

[0137] The surface area ratio of the copper foil was measured using a Keyence VK-150K 3D laser confocal microscope.

[0138] The surface contact angle of the copper foil was measured using a German Dataphysics fully automatic contact angle measuring instrument.

[0139] The signal loss of the copper foil at a frequency of 12.5 GHz was measured by an MS-101D fully automatic dielectric loss meter.

[0140] The weight-average molecular weight of polyethylene glycol is 6000;

[0141] Collagen has a gel strength of 100 Bloom.

[0142] Gelatin has a glue strength of 100 Bloom.

[0143] The iridium-plated plate used in the examples is a commercially available product from Suzhou Shuertai Industrial Technology Co., Ltd.

[0144] Example 1

[0145] (1) Preparation of raw copper foil:

[0146] Weigh out copper sulfate pentahydrate and dissolve it in deionized water. While stirring, add 120 g / L sulfuric acid. After it is completely dissolved, add hydrochloric acid to make Cu... 2+ The content is 70g / L, Cl - A copper foil electrolyte with a concentration of 20 ppm was obtained. 5 mg / L 2-mercaptopyridine, 10 mg / L 2-mercapto-1-methylimidazole, 10 mg / L collagen, and 6 mg / L polyethylene glycol were added to the copper foil electrolyte and dispersed evenly to obtain the electroplating solution.

[0147] In the electrolytic apparatus for preparing raw copper foil, an iridium-plated plate is used as the anode plate, a pure titanium plate is used as the cathode plate, the surface roughness of the cathode plate is Rz=2μm, and the current density is set to 20A / dm. 2 The copper foil electrolyte temperature was kept at 35℃ and the copper foil electrolyte circulation flow rate was 300L / min. Green copper foil was electrodeposited on the titanium plate with a surface roughness Rz=0.9μm.

[0148] (2) Slight roughening treatment:

[0149] Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and add 110 g / L sulfuric acid while stirring. Continue stirring until completely dissolved, allowing the Cu... 2+ The concentration was 15 g / L. Then, 0.1 g / L stannous sulfate, 0.1 g / L sodium vanadate, 0.5 g / L terbium nitrate, and 1 mg / L yttrium chloride were added to obtain a slightly coarsened solution.

[0150] The raw copper foil obtained in step (1) is placed in a micro-roughening solution for micro-roughening treatment, and the current density is set to 20 A / dm. 2 The micro-roughening temperature was maintained at 20°C, the micro-roughening solution circulation flow rate was 100 L / min, and the micro-roughening time was 3 s to obtain a micro-roughened copper foil. On the surface of the micro-roughened copper foil, 20 spherical copper nodules were distributed per square micrometer; the average spacing between adjacent spherical copper nodules was 10 nm; the spherical copper nodules included small and large spherical copper nodules, with the small spherical copper nodules having an average diameter of 160 nm and the large spherical copper nodules having an average diameter of 260 nm. The thickness of the roughening layer was 0.27 μm.

[0151] Compared to raw copper foil, the mass per unit area of ​​micro-roughened copper foil increases by 3 g / m². 2 Compared to raw copper foil, the surface roughness Rz of the micro-coarsened copper foil increases by 0.1 μm.

[0152] (3) Curing treatment:

[0153] Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and add 90 g / L sulfuric acid while stirring to make the Cu concentration in the solution... 2+ The concentration was 45 g / L. Then, 1 g / L lanthanum sulfate and 0.8 g / L sodium dodecyl sulfate were added to obtain the solidified solution.

[0154] The micro-coarsened copper foil obtained in step (2) was placed in a curing solution for curing treatment, and the current density was set to 20 A / dm. 2 Maintain the roughening temperature at 20℃, turn on the bubbling device to make the curing solution circulate at a flow rate of 100L / min, and cure for 6s to obtain cured copper foil.

[0155] (4) Alloying treatment:

[0156] An alloy solution was prepared using 60 g / L bismuth sulfate, 28 g / L nickel sulfate, and 1.5 g / L lanthanum sulfate as alloy sources, and 80 g / L citric acid, 20 g / L glycine, and 15 g / L triethanolamine as complexing agents. The cured copper foil was placed in the alloy solution, and a current density of 10 A / dm³ was set. 2 At a temperature of 25℃ and a processing time of 15s, alloyed copper foil was obtained.

[0157] (5) Passivation treatment:

[0158] A passivation solution was prepared using 4 g / L chromium oxide, 6 g / L sodium hydroxide, 2 g / L sodium saccharin, and 4 g / L ethylenediamine. Alloyed copper foil was placed in the passivation solution, and a current density of 20 A / dm³ was set. 2 The passivation temperature was 25℃ and the passivation time was 20s to obtain passivated copper foil.

[0159] (6) Silanization treatment:

[0160] KH560 was selected as the silane coupling agent to prepare a 1.5 mol / L silanization solution, and the pH was adjusted to 5.5 with acetic acid. Passivated copper foil was immersed in the silanization solution for 8 seconds to obtain silanized copper foil.

[0161] (7) Drying treatment:

[0162] The silanized copper foil was dried at a temperature of 100°C for 20 seconds to obtain a low-profile copper foil. The performance characteristics of the copper foil are shown in Table 1.

[0163] An example is given of the scanning electron microscope characterization of the raw copper foil obtained in step (1), such as Figure 1 As shown, the surface of the raw copper foil is very smooth.

[0164] An example is given of scanning electron microscopy (SEM) characterization of low-profile, high-peel copper foil, such as... Figure 2 As shown, highly uniform and dense nanoscale spherical copper nodule particles are formed on the surface of the copper foil.

[0165] Example 2

[0166] (1) Preparation of raw copper foil:

[0167] Weigh out copper sulfate pentahydrate and dissolve it in deionized water. While stirring, add 130 g / L sulfuric acid. After it is completely dissolved, add hydrochloric acid to make Cu... 2+ The content is 90g / L, Cl - A copper foil electrolyte with a concentration of 20 ppm was obtained. 10 mg / L 2-mercapto-1-methylimidazole, 15 mg / L collagen, and 5 mg / L polyethylene glycol were added to the copper foil electrolyte and dispersed evenly to obtain the electroplating solution.

[0168] In the electrolytic apparatus for preparing raw copper foil, an iridium-plated plate is used as the anode plate, a pure titanium plate is used as the cathode plate, the surface roughness of the cathode plate is Rz=2μm, and the current density is set to 25A / dm. 2 The copper foil electrolyte temperature was kept at 35℃ and the copper foil electrolyte circulation flow rate was 300L / min. Green copper foil was electrodeposited on the titanium plate with a surface roughness Rz=0.82μm.

[0169] (2) Slight roughening treatment:

[0170] Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and add 120 g / L sulfuric acid while stirring. Continue stirring until completely dissolved, allowing the Cu... 2+ The concentration was 10 g / L. Then, 0.5 g / L stannous sulfate, 0.05 g / L sodium vanadate, 0.2 g / L cerium nitrate, and 2 mg / L yttrium chloride were added to obtain a slightly coarsened solution.

[0171] The raw copper foil obtained in step (1) is placed in a micro-roughening solution for micro-roughening treatment, and the current density is set to 20 A / dm. 2 The micro-roughening temperature was maintained at 20℃, the micro-roughening solution circulation flow rate was 100 L / min, and the micro-roughening time was 3 s to obtain micro-roughened copper foil. On the surface of the micro-roughened copper foil, 18 spherical copper nodules were distributed per square micrometer; the average spacing between adjacent spherical copper nodules was 11 nm; the spherical copper nodules included small and large spherical copper nodules, with the small spherical copper nodules having an average diameter of 195 nm and the large spherical copper nodules having an average diameter of 320 nm. The thickness of the roughening layer was 0.31 μm. Compared to raw copper foil, the micro-roughened copper foil increased the unit area mass by 5 g / m². 2 Compared to raw copper foil, the surface roughness Rz of the micro-coarsened copper foil increases by 0.1 μm.

[0172] (3) Curing treatment:

[0173] Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and add 80 g / L sulfuric acid while stirring to make the Cu in the solution... 2+ The concentration was 50 g / L. Then, 3 g / L lanthanum sulfate and 1 g / L sodium dodecyl sulfate were added to obtain the solidified solution.

[0174] The micro-coarsened copper foil obtained in step (2) was placed in a curing solution for curing treatment, and the current density was set to 20 A / dm. 2 Maintain the roughening temperature at 20℃, turn on the bubbling device to make the curing solution circulate at a flow rate of 100L / min, and cure for 6s to obtain cured copper foil.

[0175] (4) Alloying treatment:

[0176] A bismuth sulfate (20 g / L), nickel sulfate (10 g / L), and lanthanum sulfate (3 g / L) were selected as alloy sources, and citric acid (30 g / L), glycine (8 g / L), and triethanolamine (5 g / L) were used as complexing agents to prepare an alloy solution. The cured copper foil was placed in the alloy solution, and a current density of 10 A / dm³ was set. 2 At a temperature of 25℃ and a processing time of 15s, alloyed copper foil was obtained.

[0177] (5) Passivation treatment:

[0178] A passivation solution was prepared using 2 g / L chromium oxide, 20 g / L sodium hydroxide, 10 g / L sodium saccharin, and 8 g / L ethylenediamine. The alloyed copper foil was placed in the passivation solution, and a current density of 20 A / dm³ was set. 2 The passivation temperature was 25℃ and the passivation time was 20s to obtain passivated copper foil.

[0179] (6) Silanization treatment:

[0180] KH560 was selected as the silane coupling agent to prepare a 2 mol / L silanization solution, and the pH was adjusted to 6.5 with acetic acid. Passivated copper foil was immersed in the silanization solution for 8 seconds to obtain silanized copper foil.

[0181] (7) Drying treatment:

[0182] The silanized copper foil was dried at a temperature of 100°C for 20 seconds to obtain the copper foil. The performance characteristics of the copper foil are shown in Table 1.

[0183] Example 3

[0184] (1) Preparation of raw copper foil:

[0185] Weigh out copper sulfate pentahydrate and dissolve it in deionized water. While stirring, add 110 g / L sulfuric acid. After it is completely dissolved, add hydrochloric acid to make Cu... 2+ The content is 80g / L, Cl - A copper foil electrolyte with a concentration of 15 ppm was obtained. 20 mg / L of collagen and 5 mg / L of polyethylene glycol were added to the copper foil electrolyte and dispersed evenly to obtain the electroplating solution.

[0186] In the electrolytic apparatus for preparing raw copper foil, an iridium-plated plate is used as the anode plate, a pure titanium plate is used as the cathode plate, the surface roughness of the cathode plate is Rz=2μm, and the current density is set to 35A / dm. 2 The copper foil electrolyte temperature was kept at 40℃ and the copper foil electrolyte circulation flow rate was 300L / min. Green copper foil was electrodeposited on the titanium plate with a surface roughness Rz=1.2μm.

[0187] (2) Slight roughening treatment:

[0188] Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and add 120 g / L sulfuric acid while stirring. Continue stirring until completely dissolved, allowing the Cu... 2+ The concentration was 20 g / L. Then, 1.2 g / L stannous sulfate, 0.15 g / L sodium vanadate, 0.4 g / L terbium nitrate, and 3 mg / L lanthanum chloride were added to obtain a slightly coarsened solution.

[0189] The raw copper foil obtained in step (1) is placed in a micro-roughening solution for micro-roughening treatment, and the current density is set to 20 A / dm. 2The roughening temperature was maintained at 20℃, the circulation flow rate of the roughening solution was 100 L / min, and the roughening time was 3 s to obtain a roughened copper foil. On the surface of the roughened copper foil, 17 spherical copper nodules were distributed per square micrometer; the average spacing between adjacent spherical copper nodules was 13 nm; the spherical copper nodules included small and large spherical copper nodules, with the small spherical copper nodules having an average diameter of 230 nm and the large spherical copper nodules having an average diameter of 450 nm. The roughening layer thickness was 0.41 μm. Compared to raw copper foil, the mass per unit area of ​​the roughened copper foil increased by 7 g / m². 2 Compared to raw copper foil, the surface roughness Rz of the micro-coated copper foil increases by 0.3 μm.

[0190] (3) Curing treatment:

[0191] Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and add 100 g / L sulfuric acid while stirring to make the Cu in the solution... 2+ The concentration was 65 g / L. Then, 4 g / L lanthanum sulfate and 1.5 g / L sodium dodecyl sulfate were added to obtain the solidified solution.

[0192] The micro-coarsened copper foil obtained in step (2) was placed in a curing solution for curing treatment, and the current density was set to 20 A / dm. 2 Maintain the roughening temperature at 20℃, turn on the bubbling device to make the curing solution circulate at a flow rate of 100L / min, and cure for 6s to obtain cured copper foil.

[0193] (4) Alloying treatment:

[0194] An alloy solution was prepared using 40 g / L bismuth sulfate, 15 g / L nickel sulfate, and 1 g / L lanthanum sulfate as alloy sources, and 60 g / L citric acid, 15 g / L glycine, and 10 g / L triethanolamine as complexing agents. The cured copper foil was then placed in the alloy solution, and a current density of 10 A / dm³ was set. 2 At a temperature of 25℃ and a processing time of 15s, alloyed copper foil was obtained.

[0195] (5) Passivation treatment:

[0196] A passivation solution was prepared using 6 g / L chromium oxide, 25 g / L sodium hydroxide, 8 g / L sodium saccharin, and 10 g / L ethylenediamine. Alloyed copper foil was placed in the passivation solution, and a current density of 20 A / dm³ was set. 2 The passivation temperature was 25℃ and the passivation time was 20s to obtain passivated copper foil.

[0197] (6) Silanization treatment:

[0198] KH560 was selected as the silane coupling agent to prepare a 2 mol / L silanization solution, and the pH was adjusted to 6 with acetic acid. The passivated copper foil was immersed in the silanization solution for 8 seconds to obtain silanized copper foil.

[0199] (7) Drying treatment:

[0200] The silanized copper foil was dried at a temperature of 100°C for 20 seconds to obtain a low-profile, high-peelability copper foil. The performance characteristics of the copper foil are shown in Table 1.

[0201] An exemplary scanning electron microscope (SEM) characterization of the raw copper foil obtained in step (1) is given, such as... Figure 3 As shown, the raw copper foil has large particles on its surface, uneven deposition, and inconsistent copper nodule morphology, which significantly affects subsequent roughening.

[0202] An example is given of the scanning electron microscope characterization of the prepared copper foil, such as... Figure 4 As shown, the distribution and particle size of the nodules on the copper foil surface are uneven, and there is a clear multi-layer accumulation of copper nodules. Compared with Example 1, although the surface roughness of the copper foil is slightly improved, the low-profile performance is significantly reduced.

[0203] It should be noted that, Figure 1-4 These are metallographic images taken at the same magnification.

[0204] Example 4

[0205] (1) Preparation of raw copper foil:

[0206] Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and add 90 g / L sulfuric acid while stirring. After it is completely dissolved, add hydrochloric acid to make Cu... 2+ The content is 60g / L, Cl - A copper foil electrolyte with a concentration of 30 ppm was obtained. 20 mg / L 4-mercaptobenzenesulfonic acid, 5 mg / L gelatin, and 10 mg / L polyethylene glycol were added to the copper foil electrolyte and dispersed evenly to obtain the electroplating solution.

[0207] In the electrolytic apparatus for preparing raw copper foil, an iridium-plated plate is used as the anode plate, a pure titanium plate is used as the cathode plate, the surface roughness of the cathode plate is Rz=2μm, and the current density is set to 20A / dm. 2 The copper foil electrolyte temperature was kept at 35℃ and the copper foil electrolyte circulation flow rate was 300L / min. Green copper foil was electrodeposited on the titanium plate with a surface roughness Rz=1.2μm.

[0208] (2) Slight roughening treatment:

[0209] Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and add 100 g / L sulfuric acid while stirring. Continue stirring until completely dissolved, allowing the Cu to dissolve. 2+The concentration was 20 g / L. Then, 1.5 g / L stannous sulfate, 0.05 g / L sodium vanadate, 0.3 g / L terbium nitrate, and 3 mg / L yttrium chloride were added to obtain a slightly coarsened solution.

[0210] The raw copper foil obtained in step (1) is placed in a micro-roughening solution for micro-roughening treatment, and the current density is set to 20 A / dm. 2 The micro-roughening temperature was maintained at 20℃, the micro-roughening solution circulation flow rate was 100 L / min, and the micro-roughening time was 3 s to obtain micro-roughened copper foil. On the surface of the micro-roughened copper foil, 18 spherical copper nodules were distributed per square micrometer; the average spacing between adjacent spherical copper nodules was 12 nm; the spherical copper nodules included small and large spherical copper nodules, with the small spherical copper nodules having an average diameter of 205 nm and the large spherical copper nodules having an average diameter of 375 nm. The thickness of the roughening layer was 0.47 μm. Compared to raw copper foil, the micro-roughened copper foil increased the unit area mass by 6 g / m². 2 Compared to raw copper foil, the surface roughness Rz of the micro-coarsened copper foil increases by 0.2 μm.

[0211] (3) Curing treatment:

[0212] Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and add 100 g / L sulfuric acid while stirring to make the Cu in the solution... 2+ The concentration was 40 g / L. Then, 2 g / L cerium sulfate and 0.8 g / L sodium dodecyl sulfate were added to obtain the solidified solution.

[0213] The micro-coarsened copper foil obtained in step (2) was placed in a curing solution for curing treatment, and the current density was set to 20 A / dm. 2 Maintain the roughening temperature at 20℃, turn on the bubbling device to make the curing solution circulate at a flow rate of 100L / min, and cure for 6s to obtain cured copper foil.

[0214] (4) Alloying treatment:

[0215] A nickel sulfate solution containing 20 g / L nickel sulfate and 1 g / L lanthanum sulfate was selected as the alloy source, and a complexing agent containing 20 g / L citric acid, 12 g / L glycine, and 12 g / L triethanolamine was selected as the complexing agent. The cured copper foil was placed in the alloy solution, and a current density of 10 A / dm³ was set. 2 At a temperature of 25℃ and a processing time of 15s, alloyed copper foil was obtained.

[0216] (5) Passivation treatment:

[0217] A passivation solution was prepared using 5 g / L chromium oxide, 10 g / L sodium hydroxide, 5 g / L sodium saccharin, and 5 g / L ethylenediamine. The alloyed copper foil was placed in the passivation solution, and a current density of 20 A / dm³ was set. 2The passivation temperature was 25℃ and the passivation time was 20s to obtain passivated copper foil.

[0218] (6) Silanization treatment:

[0219] KH560 was selected as the silane coupling agent to prepare a 1.5 mol / L silanization solution, and the pH was adjusted to 6 with acetic acid. The passivated copper foil was immersed in the silanization solution for 8 seconds to obtain silanized copper foil.

[0220] (7) Drying treatment:

[0221] The silanized copper foil was dried at a temperature of 100°C for 20 seconds to obtain a low-profile copper foil. The performance characteristics of the copper foil are shown in Table 1.

[0222] Example 5

[0223] (1) Preparation of raw copper foil:

[0224] Weigh out copper sulfate pentahydrate and dissolve it in deionized water. While stirring, add 150 g / L sulfuric acid. After it is completely dissolved, add hydrochloric acid to make Cu... 2+ The content is 100g / L, Cl - A copper foil electrolyte with a concentration of 30 ppm was obtained. 5 mg / L 2-mercaptopyridine, 10 mg / L 2-mercapto-1-methylimidazole, 10 mg / L collagen, and 6 mg / L polyethylene glycol were added to the copper foil electrolyte and dispersed evenly to obtain the electroplating solution.

[0225] In the electrolytic apparatus for preparing raw copper foil, an iridium-plated plate is used as the anode plate, a pure titanium plate is used as the cathode plate, the surface roughness of the cathode plate is Rz=2μm, and the current density is set to 20A / dm. 2 The copper foil electrolyte temperature was kept at 35℃ and the copper foil electrolyte circulation flow rate was 300L / min. Green copper foil was electrodeposited on the titanium plate with a surface roughness Rz=1.5μm.

[0226] (2) Slight roughening treatment:

[0227] Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and add 110 g / L sulfuric acid while stirring. Continue stirring until completely dissolved, allowing the Cu... 2+ The concentration was 15 g / L. Then, 0.1 g / L stannous sulfate, 0.5 g / L cerium nitrate, and 3 mg / L yttrium chloride were added to obtain a slightly coarsened solution.

[0228] The raw copper foil obtained in step (1) is placed in a micro-roughening solution for micro-roughening treatment, and the current density is set to 25 A / dm. 2The roughening temperature was maintained at 20℃, the circulation flow rate of the roughening solution was 100 L / min, and the roughening time was 6 s to obtain a roughened copper foil. On the surface of the roughened copper foil, 18 spherical copper nodules were distributed per square micrometer; the average spacing between adjacent spherical copper nodules was 12 nm; the spherical copper nodules included small and large spherical copper nodules, with the small spherical copper nodules having an average diameter of 210 nm and the large spherical copper nodules having an average diameter of 387 nm. The roughening layer thickness was 0.52 μm. Compared to raw copper foil, the mass per unit area of ​​the roughened copper foil increased by 7 g / m². 2 Compared to raw copper foil, the surface roughness Rz of the micro-coated copper foil increases by 0.4 μm.

[0229] (3) Curing treatment:

[0230] Weigh out copper sulfate pentahydrate, dissolve it in deionized water, and add 110 g / L sulfuric acid while stirring to make the Cu in the solution... 2+ The concentration was 40 g / L. Then, 1 g / L lanthanum sulfate and 0.8 g / L sodium dodecyl sulfate were added to obtain the solidified solution.

[0231] The micro-coarsened copper foil obtained in step (2) was placed in a curing solution for curing treatment, and the current density was set to 20 A / dm. 2 Maintain the roughening temperature at 20℃, turn on the bubbling device to make the curing solution circulate at a rate of 100L / min, and cure for 10s to obtain cured copper foil.

[0232] (4) Alloying treatment:

[0233] An alloy solution was prepared using 60 g / L bismuth sulfate, 28 g / L nickel sulfate, and 1.5 g / L lanthanum sulfate as alloy sources, and 80 g / L citric acid, 20 g / L glycine, and 15 g / L triethanolamine as complexing agents. The cured copper foil was placed in the alloy solution, and a current density of 10 A / dm³ was set. 2 At a temperature of 25℃ and a processing time of 15s, alloyed copper foil was obtained.

[0234] (5) Passivation treatment:

[0235] A passivation solution was prepared using 4 g / L chromium oxide, 6 g / L sodium hydroxide, 2 g / L sodium saccharin, and 4 g / L ethylenediamine. Alloyed copper foil was placed in the passivation solution, and a current density of 20 A / dm³ was set. 2 The passivation temperature was 25℃ and the passivation time was 20s to obtain passivated copper foil.

[0236] (6) Silanization treatment:

[0237] KH560 was selected as the silane coupling agent to prepare a 1.5 mol / L silanization solution, and the pH was adjusted to 7 with acetic acid. The passivated copper foil was immersed in the silanization solution for 8 seconds to obtain silanized copper foil.

[0238] (7) Drying treatment:

[0239] The silanized copper foil was dried at a temperature of 100°C for 20 seconds to obtain a low-profile copper foil. The performance characteristics of the copper foil are shown in Table 1.

[0240] Comparative Example 1

[0241] Copper foil produced by existing technology

[0242] It was prepared according to the method of Example 2 in CN115652384A.

[0243] Table 1

[0244]

[0245] As can be seen from the results in Table 1, the copper foil provided by this invention has ultra-low profile and high peel strength. Furthermore, the copper foil provided by this invention exhibits low signal loss at 12.5 GHz, meeting the requirements for high-frequency applications.

[0246] Meanwhile, the roughness of the copper foil in the embodiments of the present invention is much lower than that of Comparative Example 1. When the peel strength of the PPO substrate is not much different, the copper foil of the present invention has significantly better ultra-low profile performance than the copper foil of Comparative Example 1.

[0247] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing copper foil, characterized in that, The method includes the following steps: (1) Electrodeposition is performed on the electroplating solution to obtain raw copper foil; (2) The raw copper foil is placed in a coarsening solution for coarsening to obtain coarsened copper foil; (3) The micro-coarsened copper foil is placed in a curing solution for curing to obtain the copper foil; Among them, on the surface of the micro-coarsened copper foil, there are 10-20 spherical copper nodules per square micrometer of copper foil; the average spacing between adjacent spherical copper nodules is 10-20 nm. The spherical copper abscesses include small spherical copper abscesses and large spherical copper abscesses. The average diameter of the small spherical copper abscesses is 150-250 nm, and the average diameter of the large spherical copper abscesses is 260-500 nm.

2. The method according to claim 1, wherein, On the surface of the micro-coarsened copper foil, there are 15-20 spherical copper nodules distributed per square micrometer of copper foil. The average spacing between adjacent spherical copper nodules is 10-15 nm.

3. The method according to claim 1, wherein, The average diameter of small spherical copper nodules is 150-230 nm, while the average diameter of large spherical copper nodules is 260-460 nm.

4. The method according to claim 1, wherein, The average diameter ratio of small spherical copper nodules to large spherical copper nodules is 1.1-2.

5.

5. The method according to claim 4, wherein, The average diameter ratio of small spherical copper nodules to large spherical copper nodules is 1.5-2.

6. The method according to claim 1, wherein, The electroplating solution includes 65-150 g / L sulfuric acid, 60-100 g / L copper sulfate (calculated as copper ions), 10-30 ppm chloride ions, and at least one of 5-25 mg / L mercapto compounds, 5-20 mg / L amine organics, and 5-10 mg / L polyether organics.

7. The method according to claim 6, wherein, The electroplating solution includes 65-150 g / L sulfuric acid, 60-100 g / L copper sulfate (calculated as copper ions), 10-30 ppm chloride ions, and 5-25 mg / L mercapto compounds, 5-20 mg / L amine organics, and 5-10 mg / L polyether organics.

8. The method according to claim 6, wherein, The thiol compound is selected from at least one of mercaptoethanol, 2-mercapto-1-methylimidazolium, 4-mercaptobenzenesulfonic acid, sodium 3-mercapto-1-propanesulfonate, and 2-mercaptopyridine; The amine organic compound is selected from at least one of polyacrylamide, bone glue, gelatin, collagen, triisopropanolamine, and polyethyleneimine; The polyether organic compound is selected from at least one of polyoxyethylene alkyl ether, polyethylene glycol, and poly-2-ethyl-2-oxazoline.

9. The method according to claim 1, wherein, The surface roughness Rz of the raw copper foil is ≤0.9μm.

10. The method according to claim 9, wherein, The surface roughness Rz of the raw copper foil is 0.8-0.9 μm.

11. The method according to claim 1, wherein, The electrodeposition operating conditions include a current density of 15-35 A / dm³. 2 The temperature of the electroplating solution is 15-50℃; the circulation flow rate of the electroplating solution is 180-360L / min.

12. The method according to claim 11, wherein, The electrodeposition operating conditions include a current density of 20-30 A / dm³. 2 The temperature of the electroplating solution is 25-45℃; the circulation flow rate of the electroplating solution is 200-350L / min.

13. The method according to claim 1, wherein, In the electrodeposition described in step (1), the surface roughness Rz of the cathode plate is ≤2μm.

14. The method according to claim 1, wherein, In the electrodeposition described in step (1), an iridium-plated plate is used as the anode plate and a pure titanium plate is used as the cathode plate.

15. The method according to claim 1, wherein, The micro-coarsening solution comprises copper sulfate (10-40 g / L based on copper ions), sulfuric acid (80-200 g / L), vanadate (0.01-0.15 g / L), rare earth nitrate (0.1-0.5 g / L), stannous salt (0.1-1.5 g / L), and / or rare earth chloride (1-3 mg / L).

16. The method according to claim 15, wherein, The vanadate is selected from at least one of sodium vanadate, potassium vanadate, and iron vanadate; The stannous salt is stannous sulfate; The rare earth nitrate is selected from at least one of cerium nitrate, lanthanum nitrate, and terbium nitrate; The rare earth chloride is lanthanum chloride and / or yttrium chloride.

17. The method according to claim 1, wherein, The operating conditions for the micro-coarsening include: a current density of 10-35 A / dm. 2 The temperature for micro-coarsening solution preparation is 10-40℃; the circulation flow rate of the micro-coarsening solution preparation is 100-250L / min; and the micro-coarsening treatment time is 2-10s.

18. The method according to claim 17, wherein, The operating conditions for the micro-coarsening include: a current density of 15-30 A / dm. 2 The temperature for micro-coarsening solution preparation is 15-35℃; the circulation flow rate of the micro-coarsening solution preparation is 100-200L / min; and the micro-coarsening treatment time is 3-8s.

19. The method according to claim 1, wherein, The thickness of the roughened layer of the micro-roughened copper foil is 0.2-0.8 μm, where the thickness of the roughened layer is the thickness of the roughened layer attached to the surface of the raw copper foil after the roughening treatment.

20. The method according to claim 19, wherein, The thickness of the roughened layer of the micro-roughened copper foil is 0.2-0.5 μm, where the thickness of the roughened layer is the thickness of the roughened layer attached to the surface of the raw copper foil after the roughening treatment.

21. The method according to claim 1, wherein, Compared to raw copper foil, the mass per unit area of ​​slightly roughened copper foil increases by 2-8 g / m². 2 ; Compared to raw copper foil, the surface roughness Rz of micro-coated copper foil increases by 0.1-0.7 μm.

22. The method according to claim 21, wherein, Compared to raw copper foil, the mass per unit area of ​​slightly roughened copper foil increases by 3-6 g / m². 2 ; Compared to raw copper foil, the surface roughness Rz of micro-coated copper foil increases by 0.1-0.5 μm.

23. The method according to any one of claims 1-22, wherein, The curing solution comprises copper sulfate with a content of 40-70 g / L (based on copper ions), sulfuric acid with a content of 70-100 g / L, rare earth sulfate with a content of 1-5 g / L, and / or sodium dodecyl sulfate with a content of 0.5-2 g / L.

24. The method according to claim 23, wherein, The rare earth sulfate is selected from at least one of lanthanum sulfate, cerium sulfate, and terbium sulfate.

25. The method according to any one of claims 1-22, wherein, The curing operation conditions include: a current density of 20-40 A / dm³. 2 The curing solution temperature is 10-40℃; the curing solution circulation flow rate is 100-250L / min; and the curing time is 3-10s.

26. The method of claim 25, wherein, The curing operation conditions include: a current density of 20-30 A / dm³. 2 The curing solution temperature is 15-35℃; the curing solution circulation flow rate is 100-200L / min; and the curing time is 5-10s.

27. The method according to any one of claims 1-22, wherein, The method also includes: placing the cured copper foil into an alloying solution for alloying treatment to obtain alloyed copper foil.

28. The method according to claim 27, wherein, The alloying operation conditions include: a current density of 1-15 A / dm³. 2 The alloying solution temperature is 10-35℃; the alloying treatment time is 3-25s.

29. The method according to claim 28, wherein, The alloying operation conditions include: a current density of 2-11 A / dm³. 2 The alloying solution temperature is 15-25℃; the alloying treatment time is 5-20s.

30. The method according to claim 27, wherein, The alloying solution comprises 1-100 g / L of alloy source and 3-130 g / L of complexing agent.

31. The method according to claim 30, wherein, The alloy source is a soluble metal salt.

32. The method according to claim 31, wherein, The alloy source is selected from at least one of nickel salts, tungsten salts, zirconium salts, hafnium salts, cobalt salts, molybdenum salts, bismuth salts, and rare earth salts.

33. The method according to claim 32, wherein, The alloy source is selected from at least one of nickel sulfate, sodium tungstate, zirconium sulfate, hafnium sulfate, cobalt sulfate, sodium molybdate, cerium sulfate, bismuth sulfate, lanthanum sulfate, praseodymium sulfate, and dysprosium sulfate.

34. The method according to claim 33, wherein, The alloy source is selected from at least one of nickel sulfate, bismuth sulfate, and lanthanum sulfate.

35. The method according to claim 34, wherein, The alloying solution comprises at least one of 10-62 g / L bismuth sulfate, 10-28 g / L nickel sulfate, and 1-3 g / L lanthanum sulfate.

36. The method according to claim 30, wherein, The complexing agent is selected from at least one of citric acid, glycine, and triethanolamine.

37. The method according to claim 36, wherein, The alloying solution comprises at least one of 14-87 g / L citric acid, 5-20 g / L glycine, and 3-15 g / L triethanolamine.

38. The method according to claim 27, wherein, The method further includes: placing the alloyed copper foil into a silanization solution for silanization treatment to obtain the copper foil.

39. The method according to claim 38, wherein, The silanization operation time is 3-10 seconds.

40. The method of claim 38, wherein, The silanization solution includes a silane coupling agent and a pH adjuster, the pH value of the silanization solution is 5-7, and the concentration of the silanization solution is 1-3 mol / L.

41. The method according to claim 40, wherein, The silane coupling agent is selected from at least one of KH550 silane coupling agent, KH560 silane coupling agent, KH570 silane coupling agent, and KH590 silane coupling agent.

42. The method according to claim 38, wherein, The method further includes: performing passivation treatment before silanizing the alloyed copper foil.

43. The method according to claim 42, wherein, The passivation operating conditions include a current density of 10-20 A / dm². 2 The passivation solution temperature is 15-25℃; the passivation treatment time is 10-20s.

44. The method according to claim 42, wherein, The passivation solution comprises at least one of 2-6 g / L chromium oxide, 6-30 g / L sodium hydroxide, 2-15 g / L sodium saccharin, and 4-12 g / L ethylenediamine.

45. The method according to claim 44, wherein, The passivation solution comprises 2-6 g / L chromium oxide, 6-30 g / L sodium hydroxide, 2-15 g / L sodium saccharin, and 4-12 g / L ethylenediamine.

46. ​​A copper foil prepared by the method of any one of claims 1-45.

47. The copper foil according to claim 46, wherein, The surface roughness of the copper foil is Ra≤0.2μm; surface roughness Rz≤1μm; The surface contact angle of the copper foil is 75-105°; The copper foil exhibits a peel strength ≥0.6 N / mm on PPO substrate at 150-200℃ and a peel strength ≥1.1 N / mm on FR-4 substrate at 150-170℃. The surface area ratio of the copper foil is 1-2, wherein the surface area ratio of the copper foil is the ratio of the outline surface area to the planar area of ​​the copper foil; The copper foil has a unit area mass of 100-200 g / m². 2 ; The copper foil has a signal loss of 1-3 dB / m at a frequency of 12.5 GHz.

48. The copper foil according to claim 47, wherein, The surface roughness Ra of the copper foil is 0.1-0.2 μm; the surface roughness Rz is 0.8-1 μm. The surface contact angle of the copper foil is 80-95°; The copper foil has a peel strength of 0.6-1 N / mm on PPO substrate at 150-200℃ and a peel strength of 1.2-1.8 N / mm on FR-4 substrate at 150-170℃. The surface area ratio of the copper foil is 1.4-1.9, wherein the surface area ratio of the copper foil is the ratio of the outline surface area to the planar area of ​​the copper foil; The copper foil has a unit area mass of 150-170 g / m². 2 ; The copper foil has a signal loss of 1.4-2 dB / m at a frequency of 12.5 GHz.

49. The application of the copper foil according to any one of claims 46-48 in 5G communication.

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