Electrolytic copper foil non-roughened surface uniform ashing treatment method

Abstract

The present application belongs to the technical field of metal surface treatment, and particularly relates to a uniform ashing treatment method for a non-roughened surface of an electrolytic copper foil. The ashing treatment method comprises the following steps: taking an electrolytic copper foil, roughening and copper plating one side of the electrolytic copper foil, i.e. a roughened surface, and not roughening and copper plating the other side, i.e. a non-roughened surface; sequentially performing the following treatments on the non-roughened surface of the electrolytic copper foil: acid copper sulfate solution immersion, electroplating of a cover layer, electroplating of a primer layer, electroplating of a barrier layer, electroplating of an ashing layer, and an anti-oxidation layer treatment, thereby obtaining a non-roughened surface of the electrolytic copper foil with a uniform ashing surface. The non-roughened surface of the copper foil obtained by the ashing treatment has a uniform and stable ashing treatment color after high-temperature lamination treatment, and after high-temperature treatment at 140-400 DEG C, the color of the non-roughened surface of the electrolytic copper foil is represented by CIT Lab color space, i.e. lightness Ln: 75-90, red / green an: 5-20, yellow / blue bn: 15-30, and the color system deviation Rn of each point of the entire wide equidistant 26 points is ≤1, and n is the nth point.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metal surface treatment, and particularly relates to a uniform ashing treatment method for a non-roughened surface of an electrolytic copper foil. BACKGROUND

[0002] The electrolytic copper foil is used to make a raw material-copper clad plate for the electronic information industry. In the process of making the copper clad plate, the roughened surface of the electrolytic copper foil is laminated and combined with a base material composed of synthetic resin and glass fiber cloth, and the non-roughened surface of the electrolytic copper foil is not subjected to the lamination and combination and is exposed, which is referred to as a non-laminated surface. The lamination process of the copper clad plate needs to be subjected to a long-time treatment under high temperature and high pressure conditions at 140-380 DEG C, and pure copper will be inevitably oxidized into black copper oxide under the conditions, which causes irreversible damage to the appearance of the copper clad plate and has an adverse effect on the manufacture of downstream PCB lines. Therefore, in order to match the PCB manufacturing capacity, the copper clad plate must have a consistent appearance, which requires that the non-roughened surface of the electrolytic copper foil has good oxidation resistance so as to have uniform color after lamination.

[0003] In order to avoid the oxidation and discoloration of the non-roughened surface of the electrolytic copper foil during the lamination process, the surface of the electrolytic copper foil is often subjected to oxidation prevention treatment so as to have good high-temperature oxidation resistance. The surface color of the electrolytic copper foil will be greatly changed after the oxidation prevention treatment, from purple red to characteristic color. The oxidation prevention treatment of the electrolytic copper foil usually includes ashing treatment, yellowing treatment and blackening treatment according to the color change of the surface of the copper foil. Among them, the ashing treatment is the first choice for the oxidation prevention treatment of the surface of the electrolytic copper foil due to its stable process, economy, environmental protection and excellent oxidation resistance. The ashing treatment is to plate a layer of zinc and / or zinc-based alloy on the surface of the copper foil, and is named because the surface is gray after the treatment. The Zn metal is relatively active and is easy to diffuse to the copper matrix due to aging or heat treatment, forming a Cu-Zn alloy, so that the color of the non-roughened surface of the electrolytic copper foil changes from gray to yellow / magenta.

[0004] In the production process of the electrolytic copper foil, different production processes often lead to unique appearance color of the non-roughened surface. In addition, due to the characteristics of the oxidation prevention process of the electrolytic copper foil, the color of the non-roughened surface of the electrolytic copper foil is often uneven in different areas, producing strip-shaped, patch-shaped and gradient uneven color difference. The color difference of the non-roughened surface produced by the oxidation prevention treatment still exists or even increases after the lamination treatment of the copper clad plate, which not only has an adverse effect on the appearance of the copper clad plate and reduces the product quality, but also seriously interferes with the accuracy of optical positioning in the PCB manufacturing process.

[0005] Therefore, it is necessary to develop a uniform ashing treatment method for the non-roughened surface of the electrolytic copper foil, which can make the non-roughened surface of the copper foil have uniform and stable ashing treatment color after high-temperature lamination treatment. SUMMARY

[0006] In view of the above deficiencies mentioned in the background art, the purpose of the present application is to provide a non-roughened surface uniform graying treatment method for electrolytic copper foil, the non-roughened surface of the electrolytic copper foil obtained by the treatment method has a uniform graying surface, after high temperature treatment at 140-400℃, the color of the non-roughened surface of the electrolytic copper foil is represented by CIT Lab color space, the color is brightness Ln: 75-90, red / green an: 5-20, yellow / blue bn: 15-30, and the color system deviation Rn of each point of the whole width equidistant 26 points is ≤1, where n is the nth point.

[0007] In order to achieve the above purpose, the present application provides a non-roughened surface uniform graying treatment method for electrolytic copper foil, comprising the following steps:

[0008] S1. Take an electrolytic copper foil, the surface roughness Ra of which is 0.1-0.4 µm, and the surface roughness Rz is 0.8-20 µm; one side of the electrolytic copper foil is subjected to roughened copper plating treatment, i.e. roughened surface, and the other side is not subjected to roughened copper plating treatment, i.e. non-roughened surface; the electrolytic copper foil generally has two characteristic surfaces, i.e. smooth surface and rough surface, wherein the smooth surface is the surface in contact with the cathode titanium roller, which has a flat surface microtopography copied from the surface of the titanium roller; the rough surface is the surface away from the cathode titanium roller, which has a mountainous surface or a smooth surface microtopography. In the technical solution, the rough surface or the smooth surface is randomly selected for roughened copper plating treatment (roughened surface), and the non-roughened surface is not subjected to roughened treatment;

[0009] S2. The non-roughened surface of the electrolytic copper foil is sequentially subjected to acid copper sulfate solution immersion, electroplating of cover layer, electroplating of primer layer, electroplating of barrier layer, electroplating of graying layer, and anti-oxidation layer treatment, thereby obtaining the non-roughened surface of the electrolytic copper foil with uniform graying surface.

[0010] In the technical solution, the non-roughened surface is immersed in acid copper sulfate solution, then electroplated with cover layer, which can cover some defects on the surface of the copper foil, so that the surface has more uniform microtopography and appearance characteristics; then electroplated with primer layer, which has good uniform plating and covering ability, thereby improving the uniformity and conductivity of the plating layer; then electroplated with barrier layer, which improves the high temperature oxidation resistance of the electrolytic copper foil and controls the electroplating and diffusion behavior of the graying layer; then electroplated with graying layer, which further improves the high temperature stability of the electrolytic copper foil, so that the electrolytic copper foil has a uniform and beautiful surface after lamination; finally, the anti-oxidation treatment is performed to improve the oxidation resistance of the electrolytic copper foil, and the non-roughened surface of the copper foil obtained is uniform, has good high temperature stability, and has uniform and stable graying treatment color after high temperature lamination treatment.

[0011] Further, in the above technical solution, the electroplating cover layer is a smooth copper plating layer with a thickness of 0.05-0.5 µm; the smooth copper electroplating solution of the smooth copper plating layer comprises 40-80 g / L Cu 2+, 60-150 g / L H2SO4, 0.9-2.0 g / L smooth copper additive, the electroplating process is that the temperature is 40-70 ℃, the current density is 10-50 A / dm 2 , and the electroplating time is 2.5-15 s. In the technical scheme, the acid copper electroplating solution is used for electroplating the covering layer, and the smooth copper plating layer obtained can cover some possible defects on the surface of the copper foil, so that the copper foil has more uniform micro-morphology and appearance characteristics.

[0012] Further, in the technical scheme, the smooth copper additive comprises 0.1-0.5 g / L gelatin, 50-200 mg / L sodium polydithiobis propane sulfonate, 10-50 mg / L chloride ions and 0.8-1.3 g / L surfactant; the surfactant is one or more of triethanolamine, cellulose and polyethylene glycol.

[0013] Further, in the technical scheme, the electroplating base layer is a Cu-Zn alloy layer with a thickness of 10-35 nm, and the content of Zn in the Cu-Zn alloy layer is 20-40 wt%. The Cu-Zn alloy electroplating process has good uniform plating and covering capacity, and the plating layer is uniform and has good conductivity. By electroplating the Cu-Zn alloy layer on the surface of the covering layer, on the one hand, the local resistance caused by the additive inclusions in the smooth copper electroplating process is reduced, and the electroplating of the barrier layer and the ashing layer is avoided; on the other hand, the bottom layer has a light refraction effect, and the uniformity of the appearance color of the ashing layer is improved.

[0014] Further, in the technical scheme, the plating solution for electroplating the Cu-Zn alloy layer is composed of 10-50 g / L CuSO4, 5-30 g / L ZnSO4, 5-25 g / L NaOH or KOH, and 20-350 g / L complexing agent; the electroplating process is that the temperature of the plating solution is 25-55 ℃, the current density is 0.3-5 A / dm 2 , and the electroplating time is 1-10 s; the complexing agent is one or two or three of potassium pyrophosphate, disodium hydrogen phosphate, citric acid, lactic acid, nitrilotriacetic acid, N,N,N,N-tetra-2-ethylenediamine and potassium sodium tartrate.

[0015] Further, in the technical scheme, the electroplating barrier layer is a Ni-based alloy layer with a total amount of alloying elements of 0.4-0.9 µg / cm 2 ; the content of Ni in the Ni-based alloy layer is 0.3-0.7 µg / cm 2The Ni-based alloy layer is any one of Ni-Zn, Ni-Zn-P, Ni-P, Ni-Co, Ni-Mo alloy, and is preferably Ni-P or Ni-Mo alloy. The present application improves the high-temperature oxidation resistance of the electrolytic copper foil by electroplating a thin Ni-based alloy layer, and controls the electroplating and diffusion behavior of the ash layer. The Ni-based alloy microstructure is dense, which can change the deposition potential of Zn metal on the surface of the electrolytic copper foil and control the diffusion rate of the ash layer to the copper matrix at high temperature, so that the ash layer in the whole width uniformly diffuses to the copper matrix during heat treatment or aging treatment.

[0016] Further, in the above technical solution, when the Ni-based alloy layer is a Ni-P or Ni-Mo alloy layer, the plating solution is composed of 1.5-4.5 g / L NiSO4, 0-1.5 g / L Na2MoO4, and 0.5-30 g / L buffer, and the electroplating process is as follows: the current density is 0.1-1.5 A / dm 2 , and the electroplating time is 1-10 s; the buffer is composed of one or two of NaH2PO2, trisodium citrate, and H3BO3.

[0017] Further, in the above technical solution, the electroplated ash layer is a layer of Zn metal or Zn-based alloy, wherein the content of Zn metal is 2.5-20 µg / cm 2 , and preferably 3.0-10 µg / cm 2 . The electroplated ash layer in the present technical solution can further improve the high-temperature stability of the electrolytic copper foil, so that the electrolytic copper foil has a uniform and beautiful surface after lamination.

[0018] Further, in the above technical solution, the plating solution for electroplating Zn metal or Zn-based alloy is composed of 0.5-10 g / L Zn 2+ , 30-150 g / L buffer, and 0.2-20 g / L plating layer stabilizer, and the electroplating process is as follows: the plating solution temperature is 25-50℃, the current density is 0.5-8 A / dm 2 , and the electroplating time is 3-10 s.

[0019] Further, in the above technical solution, the buffer is two or three of NaOH, K4P2O7, and H3BO3; and the plating layer stabilizer is one or two of vanillin, EDTA, sodium citrate, sodium tartrate, and sodium acetate.

[0020] Further, in the above technical solution, the anti-oxidation layer is obtained by electroplating Cr salt, spraying, or soaking an organic anti-oxidation agent; and the organic anti-oxidation agent is one or two of neutral epoxy silane, glyceride, acrylic acid, or acrylic ester.

[0021] Compared with the prior art, the present application has the following advantages:

[0022] The electrolytic copper foil non-roughened surface has a uniform gray surface, and after over one week of room temperature aging treatment or high temperature treatment at 140-400℃, the gray Zn layer can uniformly diffuse to the copper matrix, and the non-roughened surface presents a stable yellow / magenta color, and the surface color system CIT Lab of the whole width equidistant 26 points is lightness L: 75-90, red / green a: 5-20, yellow / blue b: 15-30, and the color system deviation R of each point is ≤1. DETAILED DESCRIPTION

[0023] The experimental methods in the following examples are all conventional methods unless otherwise specified. The raw materials involved in the following examples are all ordinary commercially available products and can be purchased on the market.

[0024] The above technical features of the present application and the technical features described in detail below (such as the implementation cases) can be combined with each other to form new or preferred technical solutions.

[0025] The raw materials involved in the embodiments of the present application are either commercially available products or can be prepared according to existing methods. Among them, the smoothness roughness Ra of the electrolytic copper foil is 0.25 µm, and the roughness Rz of the matte surface is 5.9 µm.

[0026] The specific content of the present application is further explained and described below in combination with examples.

[0027] Example 1

[0028] A uniform gray treatment method for the non-roughened surface of an electrolytic copper foil, comprising the following steps:

[0029] S1. Take an electrolytic copper foil, and roughen and plate copper on the bright surface of the electrolytic copper foil by a conventional method, i.e. roughened surface, and do not roughen and plate copper on the matte surface, i.e. non-roughened surface;

[0030] S2. sequentially perform the following treatments on the non-roughened surface of the electrolytic copper foil: acid copper sulfate solution immersion, electroplating of a covering layer, electroplating of a primer layer, electroplating of a barrier layer, electroplating of a gray layer, and oxidation prevention layer treatment, wherein,

[0031] Electroplating of a covering layer: electroplating a smooth copper layer using an acid copper electroplating solution, wherein the composition of the electroplating solution is 60 g / L Cu 2+, 90 g / L H2SO4, 1.32 g / L smooth copper additive (consisting of 0.2 g / L gelatin, 100 mg / L sodium polydithioldipropyl sulfonate, 20 mg / L chloride ion, 0.2 g / L triethanolamine, 0.8 g / L cellulose) consisting of 30 g / L CuSO4, 27 g / L ZnSO4, 15 g / L NaOH, 225 g / L complexing agent (consisting of 200 g / L potassium pyrophosphate, 25 g / L N,N,N,N-tetra-2-ethylenediamine), the plating solution temperature is 45°C, the current density is 1.5 A / dm 2 , and the plating time is 3 s, the Zn content in the Cu-Zn alloy layer is 23 wt%, and the thickness is 12 nm;

[0032] The Cu-Zn alloy layer is plated by using a Cu-Zn alloy plating process, wherein the plating solution for plating the Cu-Zn alloy layer consists of 30 g / L CuSO4, 27 g / L ZnSO4, 15 g / L NaOH, and 225 g / L complexing agent (consisting of 200 g / L potassium pyrophosphate, 25 g / L N,N,N,N-tetra-2-ethylenediamine), the plating solution temperature is 45°C, the current density is 1.5 A / dm 2 , and the plating time is 3 s, the Zn content in the Cu-Zn alloy layer is 23 wt%, and the thickness is 12 nm;

[0033] The barrier layer is obtained by plating a thin Ni-based alloy, wherein the barrier layer Ni-based alloy is Ni-P, the plating solution consists of 3.0 g / L NiSO4 and 21 g / L buffer (consisting of 1.0 g / L NaH2PO2 and 20 g / L H3BO3), and the plating process is as follows: the current density is 0.5 A / dm 2 , and the plating time is 4 s; the total amount of Ni-P alloy elements obtained is 0.5 µg / cm 2 , and the Ni content is 0.44 µg / cm 2 ;

[0034] The gray layer is plated by using Zn metal or Zn-based alloy, wherein the plating solution consists of 2 g / L Zn 2+ , 138 g / L buffer (consisting of 18 g / L NaOH and 120 g / L K4P2O7), and 4 g / L plating layer stabilizer (vanillin), the plating solution temperature is 35°C, the current density is 3.7 A / dm 2 , and the plating time is 7 s, and the Zn metal content in the obtained gray layer is 7.2 µg / cm 2 ;

[0035] The oxidation-preventing layer is treated by using a Cr acid plating treatment, and thus the non-roughened surface of the electrolytic copper foil has a uniform gray surface.

[0036] Example 2

[0037] A method for uniformly gray processing a non-roughened surface of an electrolytic copper foil, comprising the following steps:

[0038] S1. Take an electrolytic copper foil, and roughen and plate copper on the bright surface of the electrolytic copper foil by a conventional method, i.e. roughened surface, and the other surface is not roughened and plated with copper, i.e. non-roughened surface;

[0039] S2. The non-roughened surface of the electrolytic copper foil is sequentially subjected to acid copper sulfate solution immersion, electroplating of a cover layer, electroplating of a base layer, electroplating of a barrier layer, electroplating of a gray layer, and oxidation prevention layer treatment, wherein,

[0040] The electroplating of the cover layer is performed by electroplating a smooth copper layer using an acid copper electroplating solution, wherein the composition of the electroplating solution consists of 75 g / L Cu 2+ , 120 g / L H2SO4, 1.465 g / L smooth copper additive (consisting of 0.3 g / L gelatin, 150 mg / L sodium polydithiopropyl sulfone, 35 mg / L chloride ion, and 0.05 g / L triethanolamine, 0.73 g / L cellulose, and 0.2 g / L polyethylene glycol), the plating solution temperature is 55°C, the current density is 19 A / dm 2 , and the electroplating time is 5 s;

[0041] The electroplating of the base layer is performed by electroplating a Cu-Zn alloy layer using a Cu-Zn alloy electroplating process, wherein the plating solution for electroplating the Cu-Zn alloy layer consists of 18 g / L CuSO4, 27 g / L ZnSO4, 10 g / L NaOH, and 180.8 g / L complexing agent (consisting of 160 g / L potassium pyrophosphate, 20 g / L nitrilotriacetic acid, and 0.8 g / L N,N,N,N-tetra-2-ethylenediamine), the plating solution temperature is 35°C, the current density is 4 A / dm 2 , the electroplating time is 2 s, the Zn content in the Cu-Zn alloy layer is 31 wt%, and the thickness is 28 nm;

[0042] The electroplating of the barrier layer is performed by electroplating a thin Ni-based alloy to obtain a barrier layer, wherein the Ni-based alloy of the barrier layer is a Ni-Mo alloy, the plating solution consists of 2.5 g / L NiSO4, 1.0 g / L Na2MoO4, and 15 g / L trisodium citrate, and the electroplating process is as follows: the current density is 1.2 A / dm 2 , the electroplating time is 3 s, the total amount of Ni-Mo alloy elements obtained is 0.8 µg / cm 2 , and the Ni content is 0.65 µg / cm 2 ;

[0043] The electroplating of the gray layer is performed by electroplating Zn metal or a Zn-based alloy, wherein the plating solution consists of 8 g / L Zn 2+, 40 g / L buffer (consisting of 35 g / L NaOH, 5 g / L H3BO3), 5 g / L plating stabilizer (sodium citrate), the plating solution temperature is 35℃, the current density is 5 A / dm 2 , the plating time is 3 s, the Zn metal content in the ash layer obtained is 7.2 µg / cm 2 ;

[0044] Anti-oxidation layer treatment: spraying neutral epoxy silane, to obtain an electrolytic copper foil non-roughened surface with a uniform ash surface.

[0045] Example 3

[0046] A method for uniformly ashing the non-roughened surface of an electrolytic copper foil, comprising the following steps:

[0047] S1. Take an electrolytic copper foil, and use a conventional method to roughen and plate copper on the roughened surface of the electrolytic copper foil, i.e. the roughened surface, and do not roughen and plate copper on the bright surface, i.e. the non-roughened surface;

[0048] S2. sequentially perform the following on the non-roughened surface of the electrolytic copper foil: acid copper sulfate solution immersion, electroplating a cover layer, electroplating a base layer, electroplating a barrier layer, electroplating an ashing layer, and anti-oxidation layer treatment, wherein,

[0049] Electroplating a cover layer: electroplating a smooth copper layer using an acid copper electroplating solution, wherein the composition of the electroplating solution consists of 45 g / L Cu 2+ , 110 g / L H2SO4, 1.365 g / L smooth copper additive (consisting of 0.13 g / L gelatin, 120 mg / L sodium polydithioldipropyl sulfonate, 15 mg / L chloride ion, and 0.9 g / L cellulose, 0.2 g / L polyethylene glycol), the plating solution temperature is 55℃, the current density is 40 A / dm 2 , and the plating time is 5 s;

[0050] Electroplating a base layer: electroplating a Cu-Zn alloy layer using a Cu-Zn alloy electroplating process, wherein the plating solution for electroplating the Cu-Zn alloy layer consists of 45 g / L CuSO4, 30 g / L ZnSO4, 5 g / L NaOH, 257 g / L complexing agent (consisting of 250 g / L potassium pyrophosphate, 5 g / L nitrilotriacetic acid, and 2 g / L N,N,N,N-tetra-2-ethylenediamine), the plating solution temperature is 35℃, the current density is 0.5 A / dm 2 , the plating time is 8 s, the Zn content in the Cu-Zn alloy layer is 33wt%, and the thickness is 12 nm;

[0051] Electroplating barrier layer: a layer of electroplating barrier layer is obtained by electroplating thin Ni-based alloy, wherein the barrier layer Ni-based alloy is Ni-P alloy, the plating solution is composed of 3.0 g / L NiSO4 and 21 g / L buffer (consisting of 1.0 g / L NaH2PO2 and 20 g / L H3BO3), and the electroplating process is as follows: current density is 0.3 A / dm 2 , and electroplating time is 8 s; the total amount of the obtained Ni-P alloy elements is 0.6 µg / cm 2 , and the content of Ni is 0.52 µg / cm 2 ;

[0052] Electroplating ash layer: Zn metal or Zn-based alloy is electroplated, wherein the plating solution is composed of 1.5 g / L Zn 2+ , 127 g / L buffer (consisting of 12 g / L NaOH, 85 g / L K4P2O7 and 30 g / L H3BO3), 12 g / L plating layer stabilizer (consisting of 10 g / L EDTA and 2 g / L sodium tartrate), the temperature of the plating solution is 40℃, the current density is 2.5 A / dm 2 , the electroplating time is 4 s, and the content of Zn metal in the obtained ash layer is 3.8 µg / cm 2 ;

[0053] Anti-oxidation layer treatment: glyceride organic anti-oxidant is soaked, and thus the non-roughened surface of the electrolytic copper foil with uniform ash surface is obtained.

[0054] Example 4

[0055] A method for uniformly ashing the non-roughened surface of an electrolytic copper foil, comprising the following steps:

[0056] S1. Taking an electrolytic copper foil, roughening and copper plating the roughened surface of the electrolytic copper foil by a conventional method, i.e. roughened surface, and not roughening and copper plating the bright surface, i.e. non-roughened surface;

[0057] S2. sequentially performing the following steps on the non-roughened surface of the electrolytic copper foil: acid copper sulfate solution soaking, electroplating cover layer, electroplating primer layer, electroplating barrier layer, electroplating ash layer and anti-oxidation layer treatment, wherein,

[0058] Electroplating cover layer: a smooth copper layer is electroplated by using an acid copper electroplating solution, wherein the composition of the electroplating solution is composed of 75 g / L Cu 2+ , 120 g / L H2SO4, 1.465 g / L smooth copper additive (consisting of 0.3 g / L gelatin, 150 mg / L sodium polydithiopropyl sulfone, 35 mg / L chloride ion and 0.05 g / L triethanolamine, 0.73 g / L cellulose and 0.2 g / L polyethylene glycol), the temperature of the plating solution is 55℃, and the current density is 30 A / dm2 The plating time is 5 s;

[0059] The plating of the base layer: a Cu-Zn alloy layer is plated by using Cu-Zn alloy plating process, wherein the plating solution for plating the Cu-Zn alloy layer is composed of 20 g / L CuSO4, 8 g / L ZnSO4, 5 g / L NaOH, 258 g / L complexing agent (consisting of 250 g / L potassium pyrophosphate, 8 g / L nitrilotriacetic acid), the temperature of the plating solution is 35℃, the current density is 2.4 A / dm 2 The plating time is 4 s, the content of Zn in the Cu-Zn alloy layer is 28wt%, and the thickness of the Cu-Zn alloy layer is 27 nm.

[0060] The plating of the barrier layer: a plating barrier layer is obtained by plating a thin Ni-based alloy, wherein the Ni-based alloy of the barrier layer is Ni-P, the plating solution is composed of 3.0 g / L NiSO4, 21 g / L buffer (consisting of 1.0 g / L NaH2PO2, 20 g / L H3BO3), the plating process is as follows: the current density is 0.8 A / dm 2 The plating time is 3 s; the total amount of the obtained Ni-P alloy elements is 0.64 µg / cm 2 The content of Ni is 0.51 µg / cm 2 ;

[0061] The plating of the ash layer: Zn metal or Zn-based alloy is plated, wherein the plating solution is composed of 8 g / L Zn 2+ , 40 g / L buffer (consisting of 5 g / L NaOH, 35 g / L H3BO3), 15 g / L plating layer stabilizer (sodium acetate), the temperature of the plating solution is 40℃, the current density is 1.7 A / dm 2 The plating time is 5 s, and the content of Zn metal in the obtained ash layer is 3.5 µg / cm 2 ;

[0062] The treatment of the anti-oxidation layer: the electrolytic copper foil non-roughened surface is immersed in an acrylic organic anti-oxidant to obtain a uniform ash surface.

[0063] Comparative Example 1

[0064] A method for uniformly ashing the non-roughened surface of an electrolytic copper foil, which is different from Example 1 in that the step of electroplating the covering layer is omitted, the plating time of the ash layer is 6 s, and the content of Zn metal in the ash layer is 6.8 µg / cm 2 , and the other steps are the same as those in Example 1.

[0065] Comparative Example 2

[0066] A uniform ashing treatment method for the non-roughened surface of electrolytic copper foil, which is different from Example 1 in that there is no electroplating covering layer and electroplating primer layer step, and the plating solution composition in the electroplating ashing layer is 8 g / L Zn 2+ , 41 g / L buffer (consisting of 4 g / L NaOH and 37 g / L H3BO3), 5 g / L plating layer stabilizer (sodium citrate), the plating solution temperature is 32℃, the current density is 3.9 A / dm 2 , the electroplating time is 8 s, and the Zn metal content in the obtained ashing layer is 7.7 µg / cm 2 ; the others are the same as Example 1.

[0067] Comparative Example 3

[0068] A uniform ashing treatment method for the non-roughened surface of electrolytic copper foil, which is different from Example 2 in that there is no electroplating covering layer, electroplating primer layer and electroplating barrier layer step, and the current density in the electroplating ashing layer is 2.2 A / dm 2 , the electroplating time is 5 s, and the Zn metal content in the obtained ashing layer is 4.3 µg / cm 2 ; the others are the same as Example 2.

[0069] Comparative Example 4

[0070] A uniform ashing treatment method for the non-roughened surface of electrolytic copper foil, which is different from Example 3 in that there is no electroplating primer layer step, and the electroplating time of the electroplating barrier layer is 2 s, the Ni-based alloy of the barrier layer is Ni-Mo alloy, the total amount of alloying elements is 0.65 µg / cm 2 , and the Ni content is 0.47 µg / cm 2 ; the others are the same as Example 3.

[0071] Comparative Example 5

[0072] A uniform ashing treatment method for the non-roughened surface of electrolytic copper foil, which is different from Example 4 in that there is no electroplating barrier layer step, and the Zn metal content in the electroplating ashing layer is 3.3 µg / cm 2 ; the others are the same as Example 4.

[0073] Comparative Example 6

[0074] A uniform ashing treatment method for the non-roughened surface of electrolytic copper foil, which is different from Example 4 in that the plating solution composition of the electroplating barrier layer is 4 g / L NiSO4, 1.2 g / L Na2MoO4, and 20 g / L trisodium citrate, and the electroplating process is that the current density is 1.2 A / dm 2 , and the electroplating time is 4 s; the Ni-based alloy of the barrier layer is Ni-Mo alloy, and the total amount of alloying elements is 1.14 µg / cm 2 , and the Ni content is 0.89 µg / cm2 ; others as in Example 4.

[0075] Test Examples

[0076] The non-roughened surfaces of the electrolytic copper foils obtained in Examples 1-4 and Comparative Examples 1-6 were treated at 200°C and 380°C for 2h, respectively, and then the color of the non-roughened surfaces of the electrolytic copper foils was detected, and the color difference of the treatment at two different temperatures was compared, and the results are shown in Tables 1-3. The calculation formula is as follows:

[0077]

[0078] Table 1 Test results of Examples 1-4

[0079]

[0080] Table 2 Test results of Comparative Examples 1-3

[0081]

[0082] Table 3 Test results of Comparative Examples 4-6

[0083]

[0084] From the results of Tables 1-3, it can be seen that the uniform graying treatment method of the non-roughened surface of the electrolytic copper foil of the present application has a uniform and stable graying treatment color after high temperature treatment, whether it is a bright surface or a rough surface, and the color difference is less than 1, which will not affect the subsequent light positioning, and the quality is good.

[0085] In the Comparative Example 1, since there is no step of electroplating the cover layer, the defects on the surface of the copper foil affect the uniformity of the surface of the copper foil to some extent, thereby affecting the subsequent ashing effect, and the color difference becomes larger after high temperature treatment. In the Comparative Example 2, since there is no step of electroplating the cover layer and the primer layer, the defects on the surface of the copper foil cannot be removed, and without the primer layer, the subsequent electroplating of the barrier layer and the ashing layer cannot be avoided, and the uniformity of the appearance color of the ashing layer cannot be improved, and the color difference is larger after high temperature treatment. In the Comparative Example 3, since there is no step of electroplating the cover layer, the primer layer and the barrier layer, in addition to the above defects, the electrolytic copper foil has poor high temperature oxidation resistance, and there is no nickel alloy, and the copper matrix has poor diffusion capacity during high temperature treatment, and is not uniform, and the color difference reaches 25.89, which has a great impact. In the Comparative Example 4, since there is no primer layer, the subsequent electroplating of the barrier layer and the ashing layer cannot be avoided, and the uniformity of the ashing layer cannot be improved, and there is a difference in the color of the local plated layer after 200°C high temperature treatment, and especially the plated layer will fall off after 380°C high temperature treatment. In the Comparative Example 5, since there is no step of electroplating the barrier layer, there is no nickel alloy for blocking, the electrolytic copper foil has poor high temperature oxidation resistance, and the copper matrix has poor diffusion capacity during high temperature treatment, and is not uniform, and the color difference reaches 24.97, which further illustrates the importance of the step of electroplating the barrier layer. In the Comparative Example 6, since the total amount of the nickel alloy elements used is too high, and the content of Ni is too high, it will also affect the uniformity of the non-roughened surface of the electrolytic copper foil, thereby increasing the color difference.

[0086] In summary, by optimizing the uniform ashing treatment process of the non-roughened surface of the electrolytic copper foil, and controlling the electroplating solution and parameters of each step, a suitable cover layer, primer layer, barrier layer and ashing layer are obtained, so that the non-roughened surface of the obtained electrolytic copper foil has a uniform ashing surface, and after high temperature treatment at 140-400°C, the ashing Zn layer can uniformly diffuse to the copper matrix, and the non-roughened surface presents yellow / magenta color, and the surface color of the whole width of the 26 equidistant points is CIT Lab, and the color difference of each point is R≤1, and the performance is excellent and the quality is good.

[0087] Finally, it should be emphasized that the above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for uniformly ashing a non-roughened surface of an electrolytic copper foil, characterized by, The method comprises the following steps: S1. Taking an electrolytic copper foil with a roughness Ra of 0.1-0.4 µm on the smooth surface and a roughness Rz of 0.8-20 µm on the rough surface; roughening and copper plating one side of the electrolytic copper foil, i.e. the roughened surface, and not roughening and copper plating the other side, i.e. the non-roughened surface; S2. sequentially performing the following treatments on the non-roughened surface of the electrolytic copper foil: acid copper sulfate solution immersion, electroplating of a cover layer, electroplating of a primer layer, electroplating of a barrier layer, electroplating of a gray layer, and an oxidation-resistant layer, thereby obtaining the non-roughened surface of the electrolytic copper foil with a uniform gray surface; the electroplated cover layer is a smooth copper plating layer with a thickness of 0.05-0.5 µm; the electroplated primer layer is a Cu-Zn alloy layer with a thickness of 10-35 nm, wherein the Zn content in the Cu-Zn alloy layer is 20-40 wt%; the electroplated barrier layer is a Ni-based alloy layer; the Ni-based alloy layer is any one of Ni-Zn, Ni-Zn-P, Ni-P, Ni-Co, and Ni-Mo alloys; The electroplated ash layer is a layer of Zn metal or Zn-based alloy, wherein the content of Zn metal is 2.5-20 µg / cm 2 .

2. The method of claim 1, wherein the non-roughened surface of the electrolytic copper foil is uniformly ashed. The smooth copper plating solution for the smooth copper plating layer is composed of 40-80 g / L Cu 2+ , 60-150 g / L H2SO4, 0.9-2.0 g / L smooth copper additive, the plating process is at a temperature of 40-70℃, a current density of 10-50 A / dm 2 , and a plating time of 2.5-15 s; the smooth copper additive comprises 0.1-0.5 g / L gelatin, 50-200 mg / L sodium polydithiobispropane sulfonate, 10-50 mg / L chloride ion, and 0.8-1.3 g / L surfactant; the surfactant is one or more of triethanolamine, cellulose, and polyethylene glycol.

3. The method of claim 1, wherein the non-roughened surface of the electrolytic copper foil is uniformly ashed. The plating solution of the electroplated Cu-Zn alloy layer is composed of 10-50 g / L CuSO4, 5-30 g / L ZnSO4, 5-25 g / L NaOH or KOH, and 20-350 g / L complexing agent; the electroplating process is as follows: the temperature of the plating solution is 25-55 ℃, the current density is 0.3-5 A / dm 2 , and the electroplating time is 1-10 s; the complexing agent is one or two or three of potassium pyrophosphate, disodium hydrogen phosphate, citric acid, lactic acid, nitrilotriacetic acid, and potassium sodium tartrate, and triethanolamine.

4. The method of claim 1, wherein the non-roughened surface of the electrolytic copper foil is uniformly ashed. The Ni-based alloy layer is Ni-P or Ni-Mo alloy; when the electroplating barrier layer is a Ni-P or Ni-Mo alloy layer, the plating solution is composed of 1.5-4.5 g / L NiSO4, 0-1.5 g / L Na2MoO4, and 0.5-30 g / L buffer agent, and the electroplating process is as follows: current density is 0.1-1.5 A / dm 2 , and electroplating time is 1-10 s; the total amount of alloy elements in the Ni-based alloy layer is 0.4-0.9 µg / cm 2 ; the content of Ni in the Ni-based alloy layer is 0.3-0.7 µg / cm 2 ; and the buffer agent is composed of one or two of NaH2PO2, trisodium citrate, and H3BO3.

5. The method of claim 1, wherein the non-roughened surface of the electrolytic copper foil is uniformly ashed. The content of the Zn metal is 3.0-10 µg / cm 2 .

6. The method of claim 1, wherein the non-roughened surface of the electrolytic copper foil is uniformly ashed. The plating solution for plating Zn metal or Zn-based alloy is composed of 0.5-10 g / L Zn 2+ , 30-150 g / L buffering agent, and 0.2-20 g / L plating layer stabilizer, and the plating process is carried out at a plating solution temperature of 25-50℃ and a current density of 0.5-8 A / dm 2 , and the plating time is 3-10 s; the buffering agent is two or three of NaOH, K4P2O7, and H3BO3; and the plating layer stabilizer is one or two of vanillin, EDTA, sodium citrate, sodium tartrate, and sodium acetate.

7. The method of claim 1, wherein the non-roughened surface of the electrolytic copper foil is uniformly ashed. the oxidation-resistant layer is obtained by electroplating a Cr salt, spraying, or immersing an organic oxidation-resistant agent; the organic oxidation-resistant agent is one or two of neutral epoxy silane, glyceride, acrylic acid, and acrylate.

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