Electrolytic copper foil for fine circuit and preparation method thereof

Abstract

The invention relates to the field of electrolytic copper foil processing and application, and discloses an electrolytic copper foil for a fine circuit and a preparation method thereof, the crystal structure of the copper foil is a polycrystalline structure mainly comprising bulk crystals, the average grain size is less than or equal to 2.0 mu m, the crystal structure is stable, and the difference value of the average grain size before and after pressing is less than or equal to 0.5 mu m. According to the method, doping is carried out on the grain boundary in the electrochemical deposition process of the matrix copper foil, mutual fusion of adjacent crystal grains of the copper foil in the thermocompression bonding process is inhibited, and the rapid etching performance of the copper foil is guaranteed. In the surface treatment process, the specific surface area of the surface of the copper foil is increased by means of a fine roughening treatment technology, and the etching rate of a roughened structure is increased.

Description

Technical Field

[0001] The present invention relates to the fields of electrolytic copper foil processing and application, and particularly to an electrolytic copper foil for fine circuits and a preparation method thereof. Background Art

[0002] At the present stage, thinning and miniaturization are clear development directions and trends in the field of electronic circuits. Printed circuit boards (PCBs) are an essential key component in electronic circuit devices. With the reduction of device size and the improvement of functional requirements, new and higher requirements are put forward for the wiring density and processability of PCBs. The processability of copper foil is one of the key factors for realizing the thinning and miniaturization of PCBs.

[0003] In the production process of PCBs, electronic circuit copper foils need to be etched into patterned circuits to form functional partitions of conductive regions and insulating regions. Therefore, the etching performance of copper foil is an important index to characterize the processability of copper foil. The etching performance of copper foil can be quantified by the etching factor (Etching factor, EF). The PCB circuit etching process and the etching factor of the circuit are as Figure 1 shown. During the etching process, a chemical reaction occurs between copper and the etching solution, and elemental copper is oxidized to copper ions in the combined state. Under the combined action of surface tension and gravity, the etching solution will chemically react with copper in the vertical and horizontal directions. Usually, the etching of copper by the etching solution in the horizontal direction is called side etching. Affected by the side etching effect, the cross-section of copper after etching treatment will exhibit non-vertical characteristics. The etching factor of the circuit formed by etching the copper foil can be calculated by Formula 1.

[0004]

[0005] Where EF is the etching factor of the circuit, Wt is the minimum width at the top of the circuit, Wb is the width at the bottom of the circuit, and T is the thickness of the copper layer.

[0006] Generally, in order to ensure the insulation reliability between adjacent circuits, it is necessary to control the etching factor of the copper foil after etching. Generally, the PCB processing requires that the etching factor of the circuit is not less than 3.0. The higher the etching factor of the circuit, the better the verticality of the circuit, and the lower the corresponding risk of short circuit in the PCB. The miniaturization development of terminal applications has put forward new and higher requirements for the wiring density of PCB boards. With the increase in the circuit density per unit area, the spacing between circuits is gradually compressed, and the etching rate is limited. Summary of the Invention

[0007] The main object of the present invention is to solve the technical problem that the etching rate of electrolytic copper foil for fine circuits cannot be improved in the prior art. An electrolytic copper foil for fine circuits, the crystal structure of the copper foil is a polycrystalline structure mainly composed of massive crystals, the average grain size is ≤ 2.0 μm, the crystal structure is stable, and the difference in the average grain size before and after pressing is ≤ 0.5 μm.

[0008] The thickness of the copper foil is ≤ 18 μm;

[0009] The tensile strength of the copper foil is ≥ 350 MPa;

[0010] The elongation of the copper foil is ≥ 5%;

[0011] The roughness Rz of the matte surface of the copper foil is ≤ 5.0 μm;

[0012] The specific surface area ratio Sdr of the matte surface of the copper foil is ≥ 30%;

[0013] The average height of the copper teeth on the matte surface of the copper foil is ≤ 4.0 μm;

[0014] The average diameter of the roughened structure of the copper foil is ≤ 1.5 μm;

[0015] After the copper foil is laminated with BT board, the normal peel strength is ≥ 3.0 lb / inch, and the peel strength after dipping in tin for 10 min is ≥ 3.0 lb / inch;

[0016] The contact angle CA of the matte surface of the copper foil is ≤ 90';

[0017] The minimum line width and line pitch L / S that the copper foil can be processed is ≥ 50 / 50 μm;

[0018] When the L / S of the copper foil is 50 / 50 μm, the etching factor EF is ≥ 5.0;

[0019] When the L / S of the copper foil is 50 / 50 μm, the etching rate ER is ≥ 15 μm / min.

[0020] The present invention also relates to a preparation method of an electrolytic copper foil for fine circuits, including the following steps:

[0021] The base copper foil is electroplated with copper to obtain a low-profile base copper foil with small-sized grains;

[0022] After the electroplating copper treatment is completed, the base copper foil is roughened and cured to obtain a roughened structure layer;

[0023] An electrochemically deposited non-copper metal functional layer is formed on the roughened structure layer;

[0024] The non-copper metal functional layer is treated with a silane coupling agent to obtain a chemical bonding layer;

[0025] The copper foil has a polycrystalline structure mainly composed of massive crystals, with an average grain size ≤ 2.0a. The crystal structure is stable, and the difference in average grain size before and after pressing is ≤ 0.5μm.

[0026] The process parameters for the electroplated copper treatment are as follows:

[0027] Copper concentration: 90 - 120 g / L

[0028] Sulfuric acid concentration: 100 - 130 g / L

[0029] Chloride ion concentration: 10 - 30 mg / L

[0030] Selenium dioxide concentration: 5 - 10 mg / L

[0031] Sodium glutamate concentration: 10 - 20 mg / L

[0032] Temperature: 45 - 55 °C

[0033] Flow rate: 40 - 50 m 3 / h

[0034] Current density: 65 - 75 A / dm 2 .

[0035] The present invention has the following beneficial effects:

[0036] In the electrolytic copper foil for fine circuits of the present invention, an electrolytic copper foil capable of achieving fine circuits with a line width / line pitch L / S not exceeding 50 / 50 μm is invented. By doping the grain boundaries during the electrochemical deposition of the substrate copper foil, the present invention inhibits the mutual fusion between adjacent grains during the hot pressing process of the copper foil, ensuring the rapid etching performance of the copper foil. During the surface treatment process, by means of the micro-roughening treatment technology, the specific surface area of the copper foil surface is increased, and the etching rate of the roughened structure is improved. The optimization of the etching performance of the substrate copper layer and the roughened structure effectively improves the practicality of the copper foil in fine circuits. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the copper foil etching process and the etching factor;

[0038] Figure 2 It is a comparison EBSD pattern of the crystal structure stability between the examples and the comparative examples, where (a) is before pressing in Example 1; (b) is after pressing in Example 1; (c) is before pressing in Comparative Example 1; (d) is before pressing in Comparative Example 1.

[0039] Figure 3 It is a comparison SEM micrograph between the examples and the comparative examples, where (a) is Example 1; (b) is Comparative Example 1;

[0040] Figure 4 Cross-sectional microscopic morphology comparison diagrams of the examples and comparative examples, where (a) Example 1; (b) Comparative Example 1;

[0041] Figure 5 Etching factor comparison diagram of the examples and comparative examples;

[0042] Figure 6 Fine line processing ability diagram of Comparative Example 1. Detailed implementation manners

[0043] Terms such as "first", "second", "third", "fourth", etc. (if any) in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. In addition, the terms "comprising" or "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0044] Methods for solving problems

[0045] The inventors of the present invention have developed an electrolytic copper foil suitable for fine lines with a stable crystal structure and fast etching performance and a preparation method thereof. On the one hand, doping is carried out between the grain boundaries of the copper foil during the electrochemical deposition process of the electrolytic copper foil to inhibit the mutual fusion of grain boundaries during the PCB processing and production process. On the other hand, during the surface treatment process of the copper foil, through micro-roughening, the specific surface area of the roughened structure is increased, the reaction area between the roughened structure and the etching solution is increased, and the etching rate is increased.

[0046] As the electrolytic copper foil for fine lines of the present invention, the selected electrochemical deposition additive can be doped at the grain boundaries of the copper foil, and the doping component can act as an isolation layer to inhibit the mutual fusion between adjacent copper grains, thereby ensuring that the copper foil has a high grain boundary density and maintaining the performance of efficient intergranular corrosion.

[0047] As the electrolytic copper foil for fine lines of the present invention, the selected micro-roughening surface treatment technology can realize the growth of roughened structures at the micron size level on the surface of the base copper foil. The reduction of the size of the roughened structure effectively increases the specific surface area of the copper foil surface and the density of active sites for the etching reaction between the copper foil surface and the etching solution. Micro-roughening surface treatment is beneficial to improving the etching rate of the etching solution on the copper foil and is beneficial to improving the fineness of the etched lines.

[0048] In the electrolytic copper foil for fine circuits of the present invention, an electrolytic copper foil with excellent etching performance during PCB processing is invented. The key lies in maintaining the stability of the crystal structure of the copper foil during the hot pressing process by doping at the grain boundaries during the electrochemical deposition process of the base copper layer; at the same time, during the surface treatment process, by means of micro-roughening treatment, the specific surface area of the copper foil surface is increased, and the etching rate of the copper foil during PCB processing is improved.

[0049] For ease of understanding, the specific process of the embodiment of the present invention is described below. The first embodiment of the electrolytic copper foil for fine circuits in the embodiment of the present invention includes:

[0050] The inventor of the present invention has developed an electrolytic copper foil for fine circuits and its preparation method. The result is that by doping the grain boundaries of the copper foil during the electrochemical deposition process of the copper foil and reducing the size of the roughened structure through micro-roughening treatment during the surface treatment process, the specific surface area of the copper foil surface is increased, achieving the above-mentioned purpose that can be used for fine circuit processing.

[0051] In the conventional copper foil production process, sodium glutamate is used as an additive during the electrochemical deposition process, and the crystal structure of the generated copper foil is mainly columnar crystals. The inventor of the present invention has developed an electrolytic copper foil for fine circuits, and a composite additive formed by an additive with a grain refinement effect and sodium glutamate with a leveling effect is used as an additive to regulate the electrochemical deposition of the copper foil during the electrochemical deposition process of the base copper layer. Conventional copper foils generally do not use additives during the surface treatment process, and there is an obvious tip discharge effect during the surface treatment of the base copper foil, and the roughened structure grows concentrated in the places where the roughness of the base copper foil is relatively high. The inventor of the present invention has developed an electrolytic copper foil for fine circuits, and micro-roughening is achieved through the introduction of additives during the surface treatment process of the base copper layer, while reducing the surface roughness of the copper foil, the specific surface area of the copper foil surface is increased.

[0052] In the electrolytic copper foil for fine circuits of the present invention, the crystal structure of the copper foil is a polycrystalline structure mainly composed of blocky crystals, the average grain size ≤ 2.0 μm, the crystal structure is stable, and the difference in the average grain size before and after pressing ≤ 0.5 μm.

[0053] In the electrolytic copper foil for fine circuits of the present invention, the thickness of the copper foil ≤ 18 μm, and preferably the thickness ≤ 12 μm.

[0054] In the electrolytic copper foil for fine circuits of the present invention, the tensile strength ≥ 350 MPa, and preferably the tensile strength ≥ 400 MPa.

[0055] In the electrolytic copper foil for fine circuits of the present invention, the elongation ≥ 5%, and preferably the elongation ≥ 7%.

[0056] In the electrolytic copper foil for fine circuits of the present invention, the roughness Rz of the matte surface of the copper foil is ≤5.0 μm, and the roughness Ra of the matte surface is ≤1.0 μm. Preferably, the roughness Rz of the matte surface is ≤4.5 μm, and the roughness Ra of the matte surface is ≤0.8 μm.

[0057] In the electrolytic copper foil for fine circuits of the present invention, the ratio Sdr of the extended area of the matte surface interface of the copper foil is ≥30%, and preferably the ratio Sdr of the extended area of the matte surface interface is ≥45%.

[0058] In the electrolytic copper foil for fine circuits of the present invention, the average height of the copper teeth on the matte surface of the copper foil is ≤4.0 μm, and preferably the average height of the copper teeth on the matte surface of the copper foil is ≤3.5 μm.

[0059] In the electrolytic copper foil for fine circuits of the present invention, the average diameter of the roughened structure of the copper foil is ≤1.5 μm, and preferably the average diameter of the roughened structure of the copper foil is ≤1.3 μm.

[0060] In the electrolytic copper foil for fine circuits of the present invention, the normal peel strength after laminating the copper foil with BT board is ≥3.0 lb / inch, and the peel strength after dipping in tin for 10 min is ≥3.0 lb / inch. Preferably, the normal peel strength after laminating the copper foil with BT board is ≥4.0 lb / inch, and the peel strength after dipping in tin for 10 min is ≥3.5 lb / inch.

[0061] In the electrolytic copper foil for fine circuits of the present invention, the contact angle CA of the matte surface of the copper foil is ≤90°, and the contact angle CA of the shiny surface is ≤90'. Preferably, the contact angle CA of the matte surface is ≤45', and the contact angle CA of the shiny surface is ≤70°.

[0062] In the electrolytic copper foil for fine circuits of the present invention, the minimum line width / space L / S that can be processed by the copper foil is ≥50 / 50 μm, and preferably the minimum line width / space L / S that can be processed is ≥30 / 30 μm.

[0063] In the electrolytic copper foil for fine circuits of the present invention, the etching factor EF of the copper foil at L / S of 50 / 50 μm is ≥5.0, and preferably the etching factor EF of the copper foil at L / S of 50 / 50 μm is ≥6.0.

[0064] In the electrolytic copper foil for fine circuits of the present invention, the etching rate ER of the copper foil at L / S of 50 / 50 μm is ≥15 μm / min, and preferably the etching rate ER of the copper foil at L / S of 50 / 50 μm is ≥25 μm / min. Specific embodiments

[0066] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0067] Example 1

[0068] Step 1: Additive-assisted electrochemical deposition of the substrate copper foil. During the electrochemical deposition of the substrate copper foil, additives with grain refinement and inhibitors with leveling effects are introduced, and a low-profile substrate copper foil with small-sized grains is deposited under the action of a direct current electric field. The process parameters during the electrochemical deposition of the substrate copper foil are as follows:

[0069] Copper concentration: 100 g / L

[0070] Sulfuric acid concentration: 115 g / L

[0071] Chloride ion concentration: 25 mg / L

[0072] Selenium dioxide concentration: 8 mg / L

[0073] Sodium glutamate concentration: 15 mg / L

[0074] Temperature: 50 °C

[0075] Flow rate: 45 m 3 / h

[0076] Current density: 70 A / dm 2

[0077] Step 2: Additive-assisted micro-roughening treatment. During the roughening treatment of the surface treatment, additives with refined particle size are introduced to reduce the particle size of the roughened structure on the copper foil surface and increase the specific surface area of the copper foil surface. The micro-roughening treatment is divided into two sub-stages: roughening and curing. The electrolyte formulations and functions of the two stages are different. In the roughening stage, in an electrolyte with high-concentration acid and low-concentration copper, the growth of the micro-roughened structure is achieved through electrochemical deposition. In the curing stage, in an electrolyte with high-concentration copper and low-concentration acid, conformal coating of the micro-roughened structure formed in the roughening stage is carried out through electrochemical deposition to enhance the bonding reliability between the roughened structure and the substrate copper layer. The process parameters during the micro-roughening treatment are as follows:

[0078] Roughening treatment stage:

[0079] Copper concentration: 15 g / L

[0080] Sulfuric acid concentration: 150 g / L

[0081] Sodium metasilicate concentration: 15 mg / L

[0082] Temperature: 25 °C

[0083] Electroplating time: 7 s

[0084] Current density: 40 A / dm 2

[0085] Curing process section:

[0086] Copper concentration: 50 g / L

[0087] Sulfuric acid concentration: 100 g / L

[0088] Potassium sodium tartrate concentration: 10 mg / L

[0089] Temperature: 50 °C

[0090] Electroplating time: 7 s

[0091] Current density: 50 A / dm 2

[0092] Step 3 Electrochemically deposit a non - copper metal functional layer. The process parameters for electrochemically depositing the non - copper metal functional layer are as follows:

[0093] Blackening process section

[0094] Ni concentration: 2.5 g / L

[0095] Potassium pyrophosphate: 85 g / L

[0096] pH value: 10

[0097] Blackening solution temperature: 30 °C

[0098] Blackening solution flow rate: 10 m 3 / h

[0099] Current density: 50 A / m 2

[0100] Electroplating time: 7 s

[0101] Step 4 Construction of the chemical bonding layer Copper foil is a typical inorganic material, and the plates used for the lamination of copper - clad laminates mainly consist of organic resins. To improve the bonding strength between the copper foil and the plates, it is usually necessary to construct a chemical bonding layer on the lamination surface of the copper foil and the plates. The construction of the chemical bonding layer usually selects a silane coupling agent to enhance the chemical bonding force between the copper foil and the plates. The process parameters during the construction of the chemical bonding layer on the copper foil surface are as follows:

[0102] Silane coupling agent: KBM - 403

[0103] Silane coupling agent solution concentration: 0.8 wt%

[0104] Temperature of silane coupling agent solution: 28°C

[0105] Flow rate of silane coupling agent solution: 2.5 m 3 / h

[0106] Coating time of silane coupling agent: 2 s

[0107] In Step 5, laminating the copper-clad laminate. The copper foil for electronic circuits is a raw material for CCL and PCB processing. It needs to be laminated with the board through hot pressing to form CCL, and further processed to form PCB products. The parameters during the lamination of the copper-clad laminate are as follows:

[0108] Resin composition of the board: BT

[0109] Resin content RC of the board: 65%

[0110] Type of glass cloth: 1078

[0111] Number of prepreg layers: 2 ply

[0112] Laminating temperature: 225°C

[0113] Laminating pressure: 500 psi

[0114] Laminating heat preservation time: 240 min

[0115] Heating rate: 5°C / min

[0116] Cooling rate: 5°C / min

[0117] In Step 6, peel strength test. After the copper foil and the board are laminated, it is not allowed that the copper foil and the board separate from each other during the downstream PCB processing and end-use. The peel strength is an important index parameter to characterize the bonding strength between the copper foil and the board and the reliability of the PCB. The process parameters for the peel strength test between the copper foil and the board are as follows:

[0118] Width of the specimen: 3.175 mm

[0119] Length of the specimen: 10 cm

[0120] Peel angle: 90°C

[0121] Peel stroke: 25 mm

[0122] Peel speed: 50 mm / min

[0123] Thickness of the copper layer: 35 μm (the 12-μm copper foil is electroplated and thickened to 35 μm)

[0124] Number of peel strength tests: 3 times

[0125] Step 7: Fine circuit processing to reduce line width and line spacing is the key to achieving high wiring density and the miniaturization, thinning, and lightening of electronic circuit devices. The main method for forming circuits is to etch the non-circuit areas while retaining the copper foil in the circuit areas during the process of processing the copper clad laminate into a PCB. The parameters during the fine circuit processing are as follows:

[0126] Chloride ion concentration of the etching solution: 220 - 250 g / L

[0127] Copper ion concentration of the etching solution: 90 - 130 g / L

[0128] pH value of the etching solution: 1.5 - 2.5

[0129] Temperature of the etching solution: 48 - 52 °C

[0130] Etching running speed: 1.5 - 3.0 m / min

[0131] Comparative example

[0132] The comparative example embodiments and the corresponding experimental results are shown in the following table:

[0133]

[0134] See Figure 2-6 , it can be intuitively found from the EBSD images of the examples and the comparative examples that the crystal size of the copper foil produced according to the process parameters of Example 1 did not change significantly before and after pressing, while the crystal size of the copper foil produced according to the process parameters of Comparative Example 1 changed significantly before and after pressing. In Example 1, a relatively small grain size was still retained after pressing, and the grain boundary density was relatively high, which was beneficial to achieving rapid etching. In Comparative Example 1, the crystal size of the copper foil increased significantly after pressing, the grain boundary density decreased significantly, and the corresponding etching rate also decreased, which was not conducive to the production and processing of fine circuits.

[0135] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrolytic copper foil for fine circuits, characterized in that: The copper foil has a crystal structure of a polycrystalline structure dominated by block crystals, an average grain size of ≤2.0 μm, a stable crystal structure, and a difference in average grain size before and after pressing of the plate of ≤0.5 μm.

2. The electrolytic copper foil for fine circuits according to claim 1, characterized in that: The copper foil thickness is ≤18 μm; The copper foil tensile strength is ≥350MPa; The elongation of the copper foil is ≥5%; The roughness of the copper foil matte surface is Rz≤5.0μm; The copper foil rough surface interface expansion area ratio Sdr ≥ 30%; The average height of the copper teeth on the rough surface of the copper foil is ≤4.0 μm; The average diameter of the copper foil roughening structure is ≤1.5 μm; The normal peel strength of the copper foil and the BT sheet after lamination is ≥3.0lb / inch, and the peel strength after tinning for 10 minutes is ≥3.0lb / inch; The contact angle CA of the rough surface of the copper foil is ≤90°; The copper foil can be processed with a minimum line width and line spacing of L / S ≥ 50 / 50 μm; The copper foil has an etching factor EF ≥ 5.0 when L / S is 50 / 50 μm; When L / S of the copper foil is 50 / 50 μm, the etching rate ER is ≥15 μm / min.

3. A method for preparing electrolytic copper foil for fine circuits, characterized in that: The following steps are involved: The base copper foil is subjected to copper electroplating treatment to obtain a low-profile base copper foil with small-sized grains; After the copper electroplating treatment is completed, the base copper foil is subjected to a roughening treatment and a curing treatment to obtain a roughened structure layer; electrochemically depositing a non-copper metal functional layer on the roughened structure layer; Treating the non-copper metal functional layer with a silane coupling agent to obtain a chemical bonding layer; The copper foil has a crystal structure of a polycrystalline structure dominated by block crystals, an average grain size of ≤2.0 μm, a stable crystal structure, and a difference in average grain size before and after pressing of the plate of ≤0.5 μm.

4. The method for preparing an electrolytic copper foil for fine circuits according to claim 3, characterized in that: The process parameters of the copper electroplating process are: Copper concentration: 90-120g / L Sulfuric acid concentration: 100-130g / L Chloride ion concentration: 10-30mg / L Selenium dioxide concentration: 5-10 mg / L Sodium glutamate concentration: 10-20mg / L Temperature: 45-55℃ Flow rate: 40-50m 3 / h Current density: 65-75A / dm 2 .

5. The method for preparing an electrolytic copper foil for fine circuits according to claim 3, characterized in that: The process parameters of the roughening treatment are: Copper concentration: 10-20g / L Sulfuric acid concentration: 140-160g / L Additive sodium metasilicate concentration: 10-20 mg / L; Temperature: 20-30℃ Plating time: 5-10s Current density: 30-50A / dm 2 .

6. The method for preparing an electrolytic copper foil for fine circuits according to claim 3, characterized in that: The process parameters of the curing treatment are: Copper concentration: 40-60g / L Sulfuric acid concentration: 90-110g / L Additive potassium sodium tartrate concentration: 5-15mg / L; Temperature: 45-55℃ Plating time: 5-10s Current density: 40-60A / dm 2 .

7. The method for preparing an electrolytic copper foil for fine circuits according to claim 3, characterized in that: The non-copper metal functional layer is one or more of a nickel-containing blackening layer, a zinc-containing graying layer, and a chromium-containing passivation layer.

8. The method for preparing an electrolytic copper foil for fine circuits according to claim 3, characterized in that: The process of the nickel-containing blackened layer is: Ni concentration: 2-3g / L Potassium pyrophosphate: 80-90g / L pH: 9.5-10.5 Blackening liquid temperature: 25-35℃ Blackening liquid flow rate: 5-15m 3 / h Current density: 40-60A / m 2 Plating time: 5-10s The process of the zinc-containing ashing layer is: Zn concentration: 1-3g / L Potassium pyrophosphate: 40-60g / L pH: 11-12 Ashing liquid temperature: 30-50℃ Ashing liquid flow rate: 5-15m 3 / h Current density: 70-80A / m 2 Plating time: 5-10s The process of the chromium-containing passivation layer is: Chromium concentration: 0.5-1.5g / L pH: 11.5-12.5 Passivation liquid temperature: 30-40℃ Passivation liquid flow rate: 5-15m 3 / h Current density: 40-60A / m 2 Electroplating time: 5-10s.

9. The method for preparing an electrolytic copper foil for fine circuits according to claim 3, characterized in that: The process of the silane coupling agent treatment is: Silane coupling agent solution concentration: 0.5-1.5wt% Silane coupling agent solution temperature: 25-30℃ Silane coupling agent solution flow rate: 1-3m 3 / h Silane coupling agent coating time: 1-5s.

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