Roughening treatment liquid and surface treatment method for low-roughness rolled copper foil for high-frequency and high-speed communication

Abstract

The invention discloses a low-roughness rolled copper foil roughening treatment liquid for high-frequency and high-speed communication and a surface treatment method. The roughening treatment liquid for the low-roughness rolled copper foil for high-frequency and high-speed communication is prepared from the following components in concentration: 10 to 20g / L of copper ions, 0.1 to 1.5 g / L of cobalt ions, 50 to 350mg / L of thiourea, 30 to 120mg / L of 3-mercapto-1-sodium propane sulfonate (MPS) and 200 to 250g / L of sulfuric acid. The roughening treatment liquid for the low-roughness rolled copper foil for high-frequency and high-speed communication is used for carrying out surface treatment on the rolled copper foil, a bright and flat copper plating layer with the uniform diameter of copper nodules smaller than or equal to 350 nm and the roughness Rz smaller than or equal to 0.7 mu m is obtained, and the rolled copper foil obtained after surface treatment can meet the requirement for ultrahigh-frequency transmission of 5G and above signals.

Description

Technical Field

[0001] The invention belongs to the technical field of rolled copper foil surface treatment, and in particular relates to a low-roughness rolled copper foil roughening treatment liquid and a surface treatment method for high-frequency and high-speed communications. Background Art

[0002] Rolled copper foil is an important component of copper clad laminates and printed circuit boards, and plays a role in transmitting signals and power. The trend of miniaturization and multifunctionality of electronic terminal products has promoted the high-density and high-performance development of copper clad laminates and printed circuit boards. Among them, the development of 5G and 6G technologies has brought about the rapid development of high-frequency copper clad laminates and high-frequency printed circuit board industries. As one of its important raw materials, the demand for high-frequency and high-speed rolled copper foil is also growing.

[0003] The high frequency / high speed of signals makes signal transmission more and more concentrated on the "surface" of rolled copper foil (called skin effect). When the frequency reaches 1 GHz, the transmission thickness of the signal on the surface of electrolytic copper foil is about 2.1μm; when the signal transmission frequency is increased to 10 GHz, the transmission thickness of the signal on the surface of rolled copper foil is 0.70μm. If high-frequency copper-clad laminates or high-frequency printed circuit boards continue to use rolled copper foil with conventional surface roughness, the result is that as the signal transmission frequency increases, the signal "distortion" caused by the skin effect will become more serious.

[0004] Chinese invention patent CN118854383A discloses a method for preparing electronic copper foil with a roughness of 1.0-1.5 μm, which comprises adding a group of organic additives including sodium polydisulfide dipropane sulfonate, hydrolyzed collagen, hydroxyethyl cellulose and polyethylene glycol to the raw foil with an additive concentration of 18-30 mg / L, and using a cathode roller with a roughness of Rz≤0.80 μm and Ra≤0.15 μm to prepare the raw foil; the raw foil is subjected to water washing 1, rolling, acid washing, water washing 2, deposition, water washing 3, roughening, water washing 4, curing, water washing 5, anti-oxidation, water washing 6, and silanization treatment to obtain an electrolytic copper foil with a roughness of 1.0-1.5 μm, which has good mechanical properties and is used in the preparation of printed circuit boards and electronic components.

[0005] Ultra-high-speed transmission of 5G and above signals requires that the material has little interference with the signal and ensures that large data transmission is not affected. Only when the surface roughness of the copper foil is lower can the impact on the high-frequency signal transmission rate be reduced. At the same time, under the premise of ensuring the bonding strength with PI and not prone to side corrosion when etching the circuit, it is ensured that the coating composition does not contain magnetic substances that affect signal transmission. Summary of the invention

[0006] In response to the requirement of high-frequency signal transmission for low roughness performance of rolled copper foil, the present invention provides a roughening treatment liquid and a surface treatment method for low-roughness rolled copper foil for high-frequency and high-speed communication. Through the method of the present invention, a bright and smooth copper-plated layer with a uniform copper nodule diameter of ≤350nm and a roughness Rz≤0.7μm is obtained. The rolled copper foil obtained after surface treatment can meet the requirement of ultra-high frequency transmission of 5G and above signals.

[0007] The present invention is achieved through the following technical solutions: A roughening treatment liquid for low-roughness rolled copper foil for high-frequency and high-speed communication includes the following components in concentrations: 10-20 g / L copper ions, 0.1-1.5 g / L cobalt ions, 50-350 mg / L thiourea, 30-120 mg / L sodium 3-mercapto-1-propane sulfonate (MPS), and 200-250 g / L sulfuric acid.

[0008] Furthermore, the following components are included in concentrations: copper ion 12-16 g / L, cobalt ion 0.5-1.2 g / L, thiourea 180-320 mg / L, sodium 3-mercapto-1-propane sulfonate (MPS) 60-110 mg / L.

[0009] Furthermore, the copper ions and cobalt ions are copper sulfate and cobalt sulfate.

[0010] The present invention also discloses a surface treatment method for a low-roughness rolled copper foil for high-frequency and high-speed communication, which uses the roughening treatment liquid for the low-roughness rolled copper foil for high-frequency and high-speed communication as described in the above claims for roughening treatment.

[0011] Furthermore, the rolled copper foil after electrolytic degreasing and pickling is pretreated, and then roughened with a low-roughness rolled copper foil roughening treatment liquid at a treatment temperature of 20 to 30°C and a current density of 10 to 30A / dm². After the roughening treatment, curing, anti-oxidation, passivation and drying treatments are performed.

[0012] Furthermore, the electrolytic degreasing conditions are 30-45 g / L sodium hydroxide, 40-50°C temperature, and 4-8 A / dm² current density; the pickling conditions are 160-200 g / L sulfuric acid concentration, 10-15 g / L copper ion concentration, and 20-40°C temperature.

[0013] Furthermore, the curing conditions are a copper ion concentration of 35 to 45 g / L, a sulfuric acid concentration of 120 to 150 g / L, a temperature of 45 to 60°C, and a current density of 15 to 35 A / dm²; the anti-oxidation conditions are a zinc ion concentration of 5.5 to 10.0 g / L, a potassium pyrophosphate concentration of 100 to 160 g / L, a pH value of 9 to 11, a temperature of 35 to 40°C, and a current density of 2 to 7 A / dm²; the passivation conditions are a chromium ion concentration of 1.5 to 6.5 g / L, a pH value of 8 to 11, a temperature of 20 to 25°C, and a current density of 3 to 7 A / dm²; and the temperature of the drying treatment is 150 to 230°C.

[0014] Furthermore, the surface treatment speed is 10 to 30 m / min.

[0015] Beneficial Effects The roughening treatment liquid for low-roughness rolled copper foil for high-frequency and high-speed communication in the present invention can be adsorbed in high current density areas (raised areas or corners), resulting in an increase in the polarization degree of the cathode region at microscopic heights, which slows down the electroplating speed there but does not affect the electroplating in low current density areas (depressed areas), and cooperates with other components to effectively control the electroplating process, thereby obtaining a bright and smooth copper-plated layer with a uniform copper nodule diameter of ≤350nm and a roughness Rz≤0.7μm. The rolled copper foil obtained after surface treatment can meet the requirements of ultra-high frequency transmission of 5G signals and above. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the SEM image of the surface treated rolled copper foil of Example 1; Figure 2 This is the SEM image of the surface treated rolled copper foil of Comparative Example 1; Figure 3 This is the SEM image of the surface treated rolled copper foil of Comparative Example 2; Figure 4 This is the SEM image of the rolled copper foil after surface treatment in comparative example 3. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below. Based on the embodiments in this application, other similar embodiments obtained by ordinary technicians in this field without making any creative work should all fall within the scope of protection of this application.

[0018] It should be noted that in order to ensure the reliability of the verification results, when the above-mentioned embodiment of the present invention and comparative example 1 are prepared into corresponding rolled copper foils, except for the above-mentioned components and parameters, other processes and parameters should be kept consistent. The thickness of the copper foil in the embodiment of the present invention and the comparative example is 35 μm, and the processing speed of the rolled copper foil is 20 m / min.

[0019] In the following examples and comparative examples, the copper ions, cobalt ions, zinc ions and chromium ions are introduced in the form of copper sulfate, cobalt sulfate, zinc sulfate and chromium sulfate.

[0020] Example 1 S1: Electrolytic degreasing: sodium hydroxide 35g / L, temperature 45℃, current density 8A / dm²; S2: Pickling: sulfuric acid concentration 180g / L, copper ion concentration 12g / L, temperature 35°C; S3: Coarsening: copper ion concentration 16g / L, cobalt ion concentration 0.8g / L, thiourea concentration 250mg / L, sodium 3-mercapto-1-propane sulfonate (MPS) 80mg / L, sulfuric acid concentration 220g / L, temperature 25℃, current density 20A / dm²; S4: Curing: copper ion concentration 40g / L, sulfuric acid concentration 130g / L, temperature 50℃, current density 25A / dm²; S5: Anti-oxidation: zinc ion concentration 8.5g / L, potassium pyrophosphate concentration 140g / L, pH value 10, temperature 38°C, current density 5A / dm²; S6: Passivation: chromium ion concentration 4.5g / L, pH value 9, temperature 23°C, current density 5A / dm²; S7: Drying: drying at 220°C.

[0021] Example 2 Steps S1, S2, S4-S7 of Example 2 are the same as those of Example 1; S3: Roughening: copper ion concentration 18g / L, cobalt ion concentration 1.2g / L, thiourea concentration 320mg / L, sodium 3-mercapto-1-propane sulfonate (MPS) 110mg / L, sulfuric acid concentration 210g / L, temperature 25℃, current density 20A / dm².

[0022] Example 3 Steps S1, S2, S4-S7 of Example 3 are the same as those of Example 1; S3: Roughening: copper ion concentration 12g / L, cobalt ion concentration 0.5g / L, thiourea concentration 180mg / L, sodium 3-mercapto-1-propane sulfonate (MPS) 60mg / L, sulfuric acid concentration 250g / L, temperature 25℃, current density 20A / dm².

[0023] Comparative Example 1 In comparative example 1, steps S1, S2, S4-S7 are the same as those in example 1, and no cobalt ions are introduced in the roughening step S3. The rest are the same as those in example 1.

[0024] Comparative Example 2 In Comparative Example 1, steps S1, S2, S4-S7 are the same as those in Example 1, thiourea is not introduced in the roughening step S3, and the rest are the same as those in Example 1.

[0025] Comparative Example 3 In comparative example 3, steps S1, S2, S4 to S7 are the same as those in example 1, MPS is not introduced in the roughening step S3, and the rest are the same as those in example 1.

[0026] Example 1: SEM image of rolled copper foil after surface treatment Figure 1 As shown, the SEM image of the rolled copper foil after surface treatment in Comparative Example 1 is as follows Figure 2 As shown, the SEM image of the rolled copper foil after surface treatment in Comparative Example 2 is as follows Figure 3 As shown, the SEM image of the rolled copper foil after surface treatment in Comparative Example 3 is as follows Figure 4 As shown; the copper nodule size, rough surface roughness Rz, and S21 (S21 [dB] = 10log10 (B / A): the smaller the S21, the smaller the transmission loss) of the rolled copper foil after surface treatment of Examples 1 to 3, Comparative Example 1 and Comparative Example 2 are shown in the following Table 1: Table 1 Compare Figures 1 to 3 As shown in Table 1, the surface treatment of the rolled copper foil by the technical solution of the present invention has a consistent copper nodule coating morphology, uniform size, high surface area ratio, dense structure, and neat directional arrangement. The uniform diameter of the straight copper nodule is ≤350nm, and the roughness of the rough surface is Rz≤0.7μm, and the peeling strength with PI can be guaranteed at the same time. The rolled copper foil prepared by the surface treatment process in Comparative Example 1 has a copper nodule diameter of ≤1.0μm and a rough surface Rz≤2.0μm.

[0027] The rolled copper foil prepared in Example 1 was subjected to the conditions of 60 GHz, and its S parameter (scattering parameter) S21 was measured. S21 is the transmission coefficient from end 1 to end 2 for 2-end matching, and the calculation formula is: S21[dB]=10log10(B / A). The smaller the S21, the smaller the transmission loss, and the more it can meet the needs of 5G transmission.

Claims

1. A low-roughness rolled copper foil roughening treatment liquid for high-frequency and high-speed communication, characterized in that: The composition comprises the following concentrations: copper ion 10-20 g / L, cobalt ion 0.1-1.5 g / L, thiourea 50-350 mg / L, sodium 3-mercapto-1-propane sulfonate 30-120 mg / L, and sulfuric acid 200-250 g / L.

2. The low-roughness rolled copper foil roughening treatment liquid for high-frequency and high-speed communication according to claim 1, characterized in that: The composition comprises the following concentrations: copper ion 12-16 g / L, cobalt ion 0.5-1.2 g / L, thiourea 180-320 mg / L, and sodium 3-mercapto-1-propane sulfonate 60-110 mg / L.

3. The low-roughness rolled copper foil roughening treatment liquid for high-frequency and high-speed communication according to claim 1 or 2, characterized in that: The copper ions and cobalt ions are copper sulfate and cobalt sulfate.

4. A surface treatment method for low-roughness rolled copper foil for high-frequency and high-speed communication, characterized in that: The roughening treatment is performed using the low-roughness rolled copper foil roughening treatment liquid for high-frequency and high-speed communication as described in any one of claims 1 to 3.

5. A surface treatment method for low-roughness rolled copper foil for high-frequency and high-speed communication, characterized in that: The rolled copper foil after electrolytic degreasing and pickling is pretreated, and then roughened with a low-roughness rolled copper foil roughening treatment liquid. The treatment temperature is 20-30°C and the current density is 10-30A / dm². After the roughening treatment, curing, anti-oxidation, passivation and drying are carried out.

6. The surface treatment method of low-roughness rolled copper foil for high-frequency and high-speed communication according to claim 5, characterized in that: The electrolytic degreasing conditions are 30-45 g / L sodium hydroxide, 40-50°C temperature, and 4-8 A / dm² current density; the pickling conditions are 160-200 g / L sulfuric acid concentration, 10-15 g / L copper ion concentration, and 20-40°C temperature.

7. The surface treatment method of low-roughness rolled copper foil for high-frequency and high-speed communication according to claim 5, characterized in that: The curing conditions are as follows: a copper ion concentration of 35 to 45 g / L, a sulfuric acid concentration of 120 to 150 g / L, a temperature of 45 to 60°C, and a current density of 15 to 35 A / dm²; the anti-oxidation conditions are as follows: a zinc ion concentration of 5.5 to 10.0 g / L, a potassium pyrophosphate concentration of 100 to 160 g / L, a pH value of 9 to 11, a temperature of 35 to 40°C, and a current density of 2 to 7 A / dm²; the passivation conditions are as follows: a chromium ion concentration of 1.5 to 6.5 g / L, a pH value of 8 to 11, a temperature of 20 to 25°C, and a current density of 3 to 7 A / dm²; and the temperature of the drying treatment is 150 to 230°C.

8. The surface treatment method of low-roughness rolled copper foil for high-frequency and high-speed communication according to claim 5, characterized in that: The speed of the surface treatment is 10-30 m / min.

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