RTF3 copper foil surface roughening treatment method

Abstract

The invention discloses an RTF3 copper foil surface roughening treatment method. The RTF3 copper foil surface roughening treatment method sequentially comprises the following steps of acid pickling, water washing, roughening, curing, water washing, alloying, anti-oxidation, passivation, silanization and drying. Wherein in the roughening treatment, a roughening prepared solution is used, the concentration of copper ions in the roughening prepared solution is 10-40 g / L, the concentration of sulfuric acid in the roughening prepared solution is 110-120 g / L, the temperature is 40-50 DEG C, the flow is controlled to be 10-15 m < 3 > / h, and the roughening current density is 20-40 A / dm < 2 >; the roughening liquid contains iron ions, chromium ions and a sodium tungstate additive, and the concentration ratio of the iron ions to the chromium ions to the sodium tungstate additive is (1-1.5): (1-1.5): (3-5); curing liquid preparation is used in the curing treatment, the concentration of copper ions in the curing liquid preparation is 60-70 g / L, the concentration of sulfuric acid in the curing liquid preparation is 110-120 g / L, the temperature is 50 + / -1 DEG C, the flow is controlled to be 13-20 m < 3 > / h, and the curing current density is 10-20 A / dm < 2 >. According to the invention, hyperfine regulation and control on the surface of the copper foil are realized, and the RTF3 copper foil with extremely low surface roughness and excellent peel strength is stably obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrolytic copper foil, and particularly relates to a RTF3 copper foil surface roughening treatment method. BACKGROUND

[0002] Electrolytic copper foil is widely used in chip packaging, copper-clad laminate, printed circuit board, advanced automotive driving assistance system, Internet data center and other high-tech fields. It is called the "nerve network" of signal transmission and communication of electronic products, and is a key basic material for packaging substrates, PCBs, lithium battery current collectors and other products. With the rapid development of 5G communication technology, Internet of Things and Internet technology, cloud storage and cloud computing, electronic products are becoming smaller, lighter, thinner, smarter and more functional, which puts forward higher requirements on the comprehensive performance of electrolytic copper foil.

[0003] In order to meet the demand of high-frequency high-speed board for high-end electronic copper foil, industry technical personnel began to study the surface treatment technology of copper foil with low roughness and high peeling strength. RTF (Reverse Treat Foil) copper foil is a kind of reverse copper foil, both sides of which are roughened to different degrees, so as to improve the peeling strength of the copper foil and make it easier to be attached to other materials as an intermediate layer. RTF electronic copper foil, as one of the basic materials of electronic industry, is widely used in printed circuit board (PCB), lithium ion battery and other fields, and its performance directly affects the overall quality and performance of electronic products.

[0004] In the surface roughening process of existing RTF copper foil, the traditional roughening technology is difficult to realize fine control of the surface of the copper foil, resulting in uneven size and unreasonable distribution of roughening particles, which not only affects the appearance quality of the copper foil, but more importantly, reduces the bonding force between the copper foil and the substrate and the stability of signal transmission. Especially in the field of high-frequency signal transmission, too high surface roughness will increase signal attenuation and affect signal integrity; and insufficient bonding force may cause the copper foil to fall off or delaminate during subsequent processing, affecting the reliability of the product. SUMMARY

[0005] To solve the above problems, the purpose of the present application is to provide a RTF3 copper foil surface roughening treatment method, which realizes ultra-fine control of the surface of the copper foil through innovative process flow and fine treatment parameters, so that the RTF copper foil after surface roughening treatment has significantly reduced roughness under the condition of ensuring high peeling resistance.

[0006] To achieve the above-mentioned purpose of the application, the technical scheme adopted by the present application is as follows:

[0007] A roughening treatment method for RTF3 copper foil surface, which sequentially comprises the following steps: pickling, water washing, roughening, solidification, water washing, alloying, anti-oxidation, passivation, silanization, and drying; wherein,

[0008] In the roughening treatment, a roughening solution is used, the copper ion concentration in the roughening solution is 10-40 g / L, the sulfuric acid concentration is 110-120 g / L, the temperature is 40-50 DEG C, the flow rate is controlled at 10-15 m 3 / h, and the roughening current density is 20-40 A / dm 2 ; the roughening solution contains iron ions, chromium ions, and sodium tungstate additives, and the concentration ratio of the iron ions, the chromium ions, and the sodium tungstate additives is 1-1.5:1-1.5:3-5;

[0009] In the solidification treatment, a solidification solution is used, the copper ion concentration in the solidification solution is 60-70 g / L, the sulfuric acid concentration is 110-120 g / L, the temperature is 50±1 DEG C, the flow rate is controlled at 13-20 m 3 / h, and the solidification current density is 10-20 A / dm 2 .

[0010] Further, in the pickling treatment, pickling is performed using a pickling solution, the copper ion concentration in the pickling solution is ≤7 g / L, the sulfuric acid concentration is 120-130 g / L, the temperature is normal temperature, and the flow rate is controlled at 7-10 m 3 / h.

[0011] Further, in the roughening treatment, a shielding is added at the anode plate.

[0012] Further, in the alloying treatment, an alloying solution is used, the cobalt ion concentration in the alloying solution is 0.7-1.0 g / L, the nickel ion concentration is 0.5-1.0 g / L, the potassium pyrophosphate concentration is 30-40 g / L, the pH value is controlled at 12±0.1, the temperature is 50±1 DEG C, the flow rate is controlled at 7-10 m 3 / h, and the current density is 2-5 A / dm 2 .

[0013] Further, in the anti-oxidation treatment, an anti-oxidation solution is used, the zinc ion concentration in the anti-oxidation solution is 3-5 g / L, the potassium pyrophosphate concentration is 30-40 g / L, the pH value is controlled at 13±0.1, the temperature is 50±1 DEG C, the flow rate is controlled at 7-10 m 3 / h, and the current density is 2-5 A / dm 2 .

[0014] Further, in the passivation treatment described above, a passivation solution is used, the passivation solution has a chromium ion concentration of 10-15 g / L, a pH of 5 or less, a temperature of room temperature, and a flow rate of 10-15 m 3 / h, and a current density of 1-3 A / dm 2 .

[0015] Further, in the silanization treatment described above, an organic silane coupling agent is sprayed, the organic silane coupling agent is one or more of silanes containing amino, propyl, ethoxy, and vinyl functional groups, the silane concentration is 1-1.2%, and the temperature is room temperature.

[0016] Further, in the drying treatment described above, the drying temperature is 150-200 DEG C, and the time is 5-10 s.

[0017] The RTF3 copper foil surface roughening treatment method has the following advantages in each step:

[0018] (1) The purpose of the pickling treatment is to remove the oxidation reaction film attached to the surface of the copper foil, the impurities adsorbed on the rough surface, and the oil stains on the surface of the copper foil, and to help eliminate the small protrusions and defects on the surface, further smooth the surface of the copper foil, and improve the appearance quality and consistency of the performance.

[0019] (2) The purpose of the roughening treatment is to increase the contact area and mechanical embedding force with the substrate material by forming a certain roughness on the surface of the copper foil, thereby significantly improving the bonding strength between the copper foil and the substrate; on the other hand, the roughening treatment can adjust the electrical properties of the copper foil surface, make the resistance uniformly distributed, and reduce the resistance value, which helps to improve the signal transmission efficiency and stability of the circuit.

[0020] (3) The solidification treatment can promote further reaction and cross-linking of the chemicals in the surface treatment layer, thereby forming a more solid and dense structure, which not only helps to improve the bonding force between the treatment layer and the copper foil substrate, but also significantly improves the corrosion resistance, oxidation resistance, and heat resistance of the copper foil.

[0021] (4) The alloying treatment uses the Co / Ni layer as a high-temperature and anti-peeling layer, and Ni can effectively prevent the problem of copper foil oxidation discoloration; the heat-resistant layer and the copper foil substrate form countless micro-batteries, and once corrosion occurs, the heat-resistant layer is first corroded as an anode, while the cathode copper foil substrate is protected (cathodic protection of the sacrificial anode), thereby achieving corrosion resistance.

[0022] (5) The anti-oxidation treatment forms an effective protective barrier on the surface of the copper foil through the zinc layer, which prevents the reaction of oxygen, moisture, and corrosive substances in the external environment with copper, thereby greatly extending the service life and stability of the copper foil.

[0023] (6), the main purpose of passivation treatment is to provide a protective film on the surface of copper foil, to enhance the stability and durability of copper foil; Passivation treatment can effectively inhibit the oxidation and corrosion reaction on the surface of copper foil, reduce the chemical activity of copper foil during storage and use, thereby significantly prolonging the service life.

[0024] (7), silanization treatment forms a stable silane film on the surface of copper foil, which can significantly enhance the corrosion resistance of copper foil, effectively block the direct contact of external corrosive medium with copper foil, thereby greatly prolonging the service life of copper foil; At the same time, silanization treatment helps to improve the hydrophobicity of the surface of copper foil, reduce the adsorption and penetration of water on the surface, and further enhance the corrosion resistance.

[0025] Due to the adoption of the technical scheme as described above, the present application has the following advantages:

[0026] The RTF3 copper foil surface roughening treatment method of the present application forms a uniform and dense micro-rough layer on the surface of the copper foil by adjusting the rough solidification current and speed parameters, which not only significantly reduces the surface roughness, but also improves the bonding force of the copper foil and the substrate; At the same time, by adding additives to the roughening solution, the corrosion resistance and oxidation resistance of the copper foil can be enhanced, and the comprehensive performance of the copper foil can be further improved; The roughening solution contains iron ions, chromium ions and sodium tungstate additives, which can be specifically adsorbed on the surface of the copper foil, causing the loss of electrode surface activity in some parts, in which case, copper ions preferentially deposit on the uncovered copper foil surface, causing the copper foil surface to rapidly grow "dendritic crystals", providing growth sites for subsequent solidification.

[0027] The RTF3 copper foil surface roughening treatment method of the present application reduces the particle size of the roughening layer by optimizing the roughening solution formula and adjusting the surface treatment process parameters, further reducing the roughness of the treated foil, so that the prepared RTF copper foil can ensure the peel strength while significantly reducing the profile; On the premise of ensuring high bonding force, lower surface roughness can be achieved to meet the high requirements of high-frequency signal transmission on the surface quality of copper foil; By optimizing the treatment process and adding additives, the service life of the copper foil is prolonged.

[0028] The RTF3 copper foil surface roughening treatment method of the present application significantly refines the particle size of the RTF3 copper foil surface roughening by adding iron ions, chromium ions and sodium tungstate additives in the roughening treatment, and by adjusting the surface treatment speed and rough solidification current density, accurately controlling the treatment process, significantly reducing the surface roughness of the RTF3 copper foil, and significantly enhancing the peel strength, heat resistance and corrosion resistance of the copper foil; The entire surface treatment process is simple and highly controllable, ensuring the stability and consistency of the production process, and finally a RTF3 copper foil product with extremely low surface roughness and excellent peel strength can be stably obtained, meeting the stringent requirements of high-end electronic material field on the performance of copper foil.

[0029] The RTF3 copper foil surface roughening treatment method has ultra-low roughness, and the roughened surface Rz≤1.5 μm, effectively reduces signal transmission loss, can also ensure high peeling strength, enhances the bonding force between the copper foil and the substrate, thereby improving the durability and reliability of the product. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a micro-SEM image of the RTF3 copper foil in Example 1;

[0031] Figure 2 is a micro-SEM image of the RTF3 copper foil in Example 2;

[0032] Figure 3 is a micro-SEM image of the RTF3 copper foil in Example 3;

[0033] Figure 4 is a micro-SEM image of the RTF3 copper foil in Example 4;

[0034] Figure 5 is a micro-SEM image of the RTF3 copper foil in Example 5;

[0035] Figure 6 is a micro-SEM image of the RTF3 copper foil in Example 6;

[0036] Figure 7 is a micro-SEM image of the RTF3 copper foil in Example 7. DETAILED DESCRIPTION

[0037] The application can be further illustrated with reference to the following examples; however, the following examples are only illustrative and the application is not limited to these examples.

[0038] Example 1

[0039] An RTF3 copper foil surface roughening treatment method, comprising the following specific steps:

[0040] S1, electrolytic preparation of green foil: the electrolytic process is performed according to conventional technology, and the prepared rough foil has a thickness of 12 μm;

[0041] S2, surface treatment: after the production of the green foil machine, the rough surface is treated on the surface treatment machine, and the running speed is 15 m / min; specifically including the following steps in order: pickling, washing, roughening, solidification, washing, alloying, oxidation prevention, passivation, silanization, and drying, wherein,

[0042] The pickling treatment conditions are: the concentration of copper ions is ≤7 g / L, the concentration of sulfuric acid is 120-130 g / L, the temperature is normal temperature, the flow is controlled at 7-10 m 3 / h, and no electricity is supplied during the pickling stage.

[0043] The roughening treatment conditions are: the concentration of copper ions is 10-15 g / L, the concentration of sulfuric acid is 110-120 g / L, the temperature is 40±1℃, the flow is controlled at 10-15 m 3 / h, the roughening current density is 20 A / dm 2 ; the roughening solution contains ferric chloride, chromium trioxide and sodium tungstate additives, and the concentration ratio of the ferric chloride, chromium trioxide and sodium tungstate additives is 1:1:5.

[0044] The solidification treatment conditions are: the concentration of copper ions is 60-70 g / L, the concentration of sulfuric acid is 110-120 g / L, the temperature is 50±1℃, the flow is controlled at 13-20 m 3 / h, and the solidification operating current density is 10 A / dm 2 .

[0045] The alloying treatment conditions are: the concentration of cobalt ions is 0.7-1.0 g / L, the concentration of nickel ions is 0.5-1.0 g / L, the concentration of potassium pyrophosphate is 30-40 g / L, the pH value is controlled at 12±0.1, the temperature is 50±1℃, the flow is controlled at 7-10 m 3 / h, and the current density is 2 A / dm 2 .

[0046] The anti-oxidation treatment conditions are: the concentration of zinc ions is 3-5 g / L, the concentration of potassium pyrophosphate is 30-40 g / L, the pH value is controlled at 13±0.1, the temperature is 50±1℃, the flow is controlled at 7-10 m 3 / h, and the current density is 2 A / dm 2 .

[0047] The passivation treatment conditions are: the concentration of chromium ions is 10-15 g / L, the pH value is ≤5, the temperature is room temperature, the flow is controlled at 10-15 m 3 / h, and the current density is 2 A / dm 2 .

[0048] The silanization treatment, spraying an organic silane coupling agent, the organic silane coupling agent is one or more of silanes containing amino, propyl, ethoxy, and vinyl functional groups; the silane concentration is 1%, and the temperature is room temperature.

[0049] In the drying treatment, the drying temperature is 150-200℃, and the time is 5-10 s.

[0050] The prepared electrolytic copper foil roughness Rz is 2.18 μm, and the peel strength is 0.836 N / mm; the electrolytic copper foil surface morphology is shown in the electron microscope as shown in Figure 1 .

[0051] Example 2

[0052] A RTF3 copper foil surface roughening treatment method, the process parameters of the electrolytic preparation of green foil process are basically the same as those of example 1, and the surface treatment process is different from that of example 1, the difference is that the copper ion concentration in the roughening solution is adjusted to 30-35 g / L, and the other electrolytic parameters are the same.

[0053] The prepared electrolytic copper foil roughness Rz is 2.11 μm, and the peel strength is 0.841 N / mm; the electrolytic copper foil surface morphology is shown in the electron microscope as shown in Figure 2 .

[0054] Example 3

[0055] A RTF3 copper foil surface roughening treatment method, the process parameters of the electrolytic preparation of green foil process are basically the same as those of example 1, and the surface treatment process is different from that of example 2, the difference is that the liquid temperature of the roughening solution is adjusted to 50±1℃, and the other parameters are the same.

[0056] The prepared electrolytic copper foil roughness Rz is 1.71 μm, and the peel strength is 0.926 N / mm; the electrolytic copper foil surface morphology is shown in the electron microscope as shown in Figure 3 .

[0057] Example 4

[0058] A RTF3 copper foil surface roughening treatment method, the process parameters of the electrolytic preparation of green foil process are basically the same as those of example 1, and in the surface treatment process, under the conditions of copper ion concentration of 30-35 g / L in the roughening solution and liquid temperature of the roughening solution of 50±1℃, the running speed is adjusted to 25 m / min, and the other parameters are the same as those of example 3.

[0059] The prepared electrolytic copper foil roughness Rz is 1.81 μm, and the peel strength is 0.793 N / mm; the electrolytic copper foil surface morphology is shown in the electron microscope as shown in Figure 4 .

[0060] Example 5

[0061] A RTF3 copper foil surface roughening treatment method, the process parameters of the electrolytic preparation of green foil process are basically the same as those of example 1, and in the surface treatment process, under the conditions of copper ion concentration of 30-35 g / L in the roughening solution and liquid temperature of the roughening solution of 50±1℃, the running speed is adjusted to 20 m / min, and the other parameters are the same as those of example 4.

[0062] The prepared electrolytic copper foil roughness Rz is 1.67 μm, and the peel strength is 0.870 N / mm; the electrolytic copper foil surface morphology is shown in Figure 5 .

[0063] Example 6

[0064] A surface roughening treatment method of RTF3 copper foil, the process parameters of the electrolytic preparation of green foil process are basically the same as those of example 1, in the surface treatment process, under the conditions that the copper ion concentration of the roughening solution is 30-35 g / L, the liquid temperature of the roughening solution is 50±1 ℃, and the running speed is 20 m / min, the roughening current density is adjusted to 40 A / dm 2 , and other parameters are the same as those of example 5.

[0065] The prepared electrolytic copper foil roughness Rz is 1.43 μm, and the peel strength is 0.919 N / mm; the electrolytic copper foil surface morphology is shown in Figure 6 .

[0066] Example 7

[0067] A surface roughening treatment method of RTF3 copper foil, the process parameters of the electrolytic preparation of green foil process are basically the same as those of example 1, in the surface treatment process, under the conditions that the copper ion concentration of the roughening solution is 30-35 g / L, the liquid temperature of the roughening solution is 50±1 ℃, the roughening current is 20 A / dm 2 , and the running speed is 20 m / min, shielding is added at the anode plate in the roughening step, and other parameters are the same as those of example 5.

[0068] The prepared electrolytic copper foil roughness Rz is 1.12 μm, and the peel strength is 0.874 N / mm; the electrolytic copper foil surface morphology is shown in Figure 7 .

[0069] Test example

[0070] (1) Test the particle size of the RTF3 copper foil in each of the above examples

[0071] The nanomeasurer software is used to observe and measure the roughening particles of the prepared copper foil. Multiple representative areas are selected at different positions of the copper foil, and the measurement area of each area is 150×200 mm 2 , the roughening particle size in each area is measured, and finally the average value of all measurement values is taken to obtain the average value of the roughening particle size of the whole width.

[0072] (2) Test the surface roughness of the RTF3 copper foil in each of the above examples

[0073] According to the test method GB / T29847-2013, the roughness Rz value of the copper foil treatment surface is tested by using a Japanese Mitutoyo portable roughness meter SJ-30L, and the average value of three roughness values is taken.

[0074] (3), test the peel strength of the electrolytic copper foil in each of the above embodiments

[0075] Using a press plate machine, the copper foil samples in examples 1 to 7 are compared with the epoxy resin substrate (Shengyi Technology semi-solidified (s1150) to determine the peel strength by using a tension testing machine.

[0076] The test data of the electrolytic copper foil in examples 1 to 7 are shown in table 1.

[0077] Table 1

[0078] Specification Treated surface Rz (μm) Peeling resistance (N / mm) Particle size (nm) Example 1 12 RTF 2.18 0.836 1290 Example 2 12 RTF 2.11 0.841 990 Example 3 12 RTF 1.71 0.926 1190 Example 4 12 RTF 1.81 0.793 830 Example 5 12 RTF 1.67 0.870 1210 Example 6 12 RTF 1.43 0.919 670 Example 7 12 RTF 1.12 0.874 530

[0079] By comparing the electron microscopes of Figure 1 and Figure 2 , it is found that appropriate increase of the copper ion concentration of the roughening solution can achieve the effect of refining the grain size, and the copper ion concentration in example 2 is most suitable; by comparing the electron microscopes and indexes of Figure 4 and Figure 5 , it can be seen that adjusting the running speed of the surface treatment can also uniformly roughen the layer grain, and the grain of the roughening layer prepared in example 5 is the most dense and uniform. Finally, by increasing the current and adding shielding at the anode plate, the deposition current density is increased, so as to increase the nucleation density. By comparing the 7 examples, it is concluded that when the roughening solution with specific conditions is used, that is, the Cu2+ concentration in the roughening solution is 40-45 g / L, the sulfuric acid concentration is 110-120 g / L, the temperature of the liquid is controlled in the range of 50±1℃, the concentration ratio of iron ion, chromium ion and sodium tungstate in the additive is 1:1:5, and the running speed is 20 m / min, the surface roughness of the RTF3 copper foil prepared is significantly reduced, the grain size of the roughening layer is obviously decreased, the microstructure and flatness are more optimal, so as to effectively improve the quality of the copper foil and the performance of the subsequent processing application.

[0080] The above only describes the preferred embodiments of the present application, and does not limit the present application, any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for roughening the surface of RTF3 copper foil, characterized in that: The process includes the following steps in sequence: pickling, washing, roughening, curing, washing, alloying, anti-oxidation, passivation, silanization, and drying; among which, The roughening treatment is carried out using a roughening solution with a copper ion concentration of 10–40 g / L, a sulfuric acid concentration of 110–120 g / L, a temperature of 40–50 °C, and a flow rate controlled at 10–15 m³ / L. 3 / h, coarsening current density is 20~40A / dm 2 The roughening solution contains iron ions, chromium ions, and sodium tungstate additives, with a concentration ratio of 1–1.5:1–1.5:3–5. The curing process is carried out using a curing solution with a copper ion concentration of 60–70 g / L, a sulfuric acid concentration of 110–120 g / L, a temperature of 50 ± 1 °C, and a flow rate controlled at 13–20 m³ / L. 3 / h, curing current density is 10~20A / dm 2 .

2. The surface roughening treatment method for RTF3 copper foil according to claim 1, characterized in that: In the pickling process, a pickling solution is used. The concentration of copper ions in the pickling solution is ≤7 g / L, the concentration of sulfuric acid is 120–130 g / L, the temperature is room temperature, and the flow rate is controlled at 7–10 m³ / L. 3 / h.

3. The surface roughening treatment method for RTF3 copper foil according to claim 1, characterized in that: In the roughening process, a shield is added at the anode plate.

4. The surface roughening treatment method for RTF3 copper foil according to claim 1, characterized in that: The alloying process is carried out using an alloying solution with a cobalt ion concentration of 0.7–1.0 g / L, a nickel ion concentration of 0.5–1.0 g / L, a potassium pyrophosphate concentration of 30–40 g / L, a pH value controlled at 12 ± 0.1, a temperature of 50 ± 1 °C, and a flow rate controlled at 7–10 m³ / L. 3 / h, current density is 2~5A / dm 2 .

5. The surface roughening treatment method for RTF3 copper foil according to claim 1, characterized in that: The oxidation prevention treatment is carried out using an oxidation prevention solution. The zinc ion concentration in the solution is 3–5 g / L, the potassium pyrophosphate concentration is 30–40 g / L, the pH is controlled at 13 ± 0.1, the temperature is 50 ± 1℃, and the flow rate is controlled at 7–10 m³ / L. 3 / h, current density is 2~5A / dm 2 .

6. The surface roughening treatment method for RTF3 copper foil according to claim 1, characterized in that: The passivation treatment is carried out using a passivation solution with a chromium ion concentration of 10–15 g / L, pH ≤ 5, room temperature, and a flow rate controlled at 10–15 m³ / L. 3 / h, current density is 1~3A / dm 2 .

7. The surface roughening treatment method for RTF3 copper foil according to claim 1, characterized in that: In the silanization process, an organosilane coupling agent is sprayed, which is one or more silanes containing amino, propyl, ethoxy, or vinyl functional groups; the silane concentration is 1-1.2%, and the temperature is room temperature.

8. The surface roughening treatment method for RTF3 copper foil according to claim 1, characterized in that: In the drying process, the drying temperature is 150-200℃ and the drying time is 5-10s.

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