Copper nodule control additive for rolled copper foil and rolled copper foil surface treatment method

Abstract

The invention discloses a rolled copper foil copper nodule control additive and a rolled copper foil surface treatment method. The rolled copper foil copper nodule control additive comprises, by concentration, 10 g / L to 20 g / L of copper ions, 0.1 g / L to 1.5 g / L of cobalt ions, 30 mg / L to 120 mg / L of sodium alcohol thiopropane sulfonate (HP) and 200 g / L to 250 g / L of sulfuric acid. The rolled copper foil copper nodule control additive is used for carrying out surface treatment on rolled copper foil, a copper nodule control treating fluid is improved, sodium alcohol sulfanyl propane sulfonate (HP) is added, and the copper ion concentration, the cobalt ion concentration, the sulfuric acid concentration and the current density are adjusted, so that the copper nodule diameter of a treated surface is smaller than or equal to 500nm, the surface area ratio is larger than or equal to 1.08, and the copper nodule surface area ratio is larger than or equal to 1.08. After the rolled copper foil is subjected to surface treatment, the copper nodule is small in size and uniform, the surface area ratio is high, oxidation is prevented, the color is stable, and the purpose of long-time preservation is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of copper alloy processing, and in particular relates to a copper nodule control additive for rolled copper foil and a surface treatment method for rolled copper foil. Background Art

[0002] Printed circuit boards (PCBs) are one of the important components of the electronics industry and are widely used in all aspects of social life, from digital products and household appliances in daily life to CNC machine tools and artificial intelligence devices in industrial production, to satellites and manned spacecraft in aerospace, all of which use printed circuit boards as carriers of integrated circuits. With the development of electronic technology, integrated circuits are developing towards "fine wires, high density, multi-level, and three-dimensional", which makes the width and spacing of integrated interconnect lines narrower, resulting in large and uneven copper nodules on the surface of rolled copper foil, low surface, poor FPC bonding strength, and high signal loss. Fine integrated circuits require that the copper nodules of rolled copper foil coatings have consistent morphology, uniform size, and high surface area ratio, effectively reducing or avoiding the "residual copper" phenomenon and the problem of loose pressing when etching the circuit, and reducing the loss of signal transmission.

[0003] In order to ensure the electrical performance between multilayer boards, a sulfate copper plating system is generally used. The process is simple, the plating solution composition is simple, the components are cheap, and the formed plating solution is stable and easy to control. The copper plating effect is determined by additives. Electroplating additives can be divided into three types according to their functions: promoters, inhibitors and levelers. Under the synergistic effect of these additives, a bright, flat and physically excellent copper deposit can be obtained. Among them, the promoter is a very important substance in the copper plating additive system, which plays a role in depolarization or reducing overpotential. On the one hand, it replaces the adsorbed inhibitor to promote the nucleation of copper. On the other hand, it preferentially adsorbs on certain crystal faces with higher activity and faster growth rate, making it difficult for the adsorbed metal ions to enter the active point, and the crystal face growth rate decreases, so that the growth rate of the entire crystal face is uniform, forming a copper nodule coating with consistent morphology, uniform size, high surface area ratio, dense structure, and neat directional arrangement.

[0004] Gu Min et al. studied the effect and mechanism of 3-mercapto-1-propane sulfonate (MPS) compound additives on copper electrodeposition. The study found that MPS-PEG inhibited while MPS-Cl and MPS-PEG-Cl promoted Cu electrodeposition; at low potential, MPS and Cl － , Cu ＋ / Cu 2＋ The intermediate product formed is adsorbed on the electrode surface; MPS inhibits the electrodeposition of Cu, but reacts with Cl － There is a synergistic effect, which plays a promoting role in super-conformal filling, which is greater than the inhibitory effect. This promoting effect comes from MPS and Cl －However, through research, it was found that when Cl was added to the plating solution － When the copper foil is used, the particles formed on the surface of the copper foil are uneven in size, some are in the shape of rice grains, some are in the shape of olives, and some may even aggregate. Therefore, it is difficult to play a positive role when it is applied at the right time. Summary of the invention

[0005] In view of the problems that copper nodules of existing surface additives are uneven in size, irregular in shape and small in specific surface area when applied to the surface roughening of copper foil, which result in poor pressing during the preparation of multilayer boards and residual copper during etching, the present invention provides a chlorine-free copper nodule control additive for rolled copper foil and a surface treatment method for rolled copper foil. Multiple components work synergistically to effectively control the electroplating process, thereby obtaining a bright and smooth copper plating layer with a copper nodule diameter of ≤500nm and a surface area ratio of ≥1.08. The copper nodule plating layer of the rolled copper foil obtained after surface treatment has consistent morphology, uniform size, high surface area ratio, dense structure and neat directional arrangement.

[0006] The present invention is achieved through the following technical solutions: A copper nodule control additive for rolled copper foil comprises the following components in concentrations: copper ion: 10-20 g / L, cobalt ion: 0.1-1.5 g / L, sodium thiopropane sulfonate (HP): 30-120 mg / L, and sulfuric acid: 200-250 g / L.

[0007] Furthermore, the copper ions and cobalt ions are copper sulfate and cobalt sulfate.

[0008] Furthermore, the copper nodule control additive for rolled copper foil includes the following components in concentrations: copper ion: 12-20 g / L, cobalt ion: 0.5-1.2 g / L, sodium thiopropane sulfonate (HP): 60-120 mg / L, sulfuric acid: 220-250 g / L.

[0009] In the present invention, a method for surface treating a rolled copper foil by using the rolled copper foil copper nodule control additive is used, wherein the copper foil after electrolytic degreasing and pickling is roughened by using a copper nodule control treatment liquid, the roughening treatment temperature is controlled at 20 to 30° C., and the current density is controlled at 10 to 30 A / dm². The treated copper foil is sequentially cured, anti-oxidized, passivated and dried.

[0010] Furthermore, the roughening treatment temperature is 25-28°C, and the current density is 15-25A / dm².

[0011] Furthermore, the treatment conditions for electrolytic degreasing are: sodium hydroxide 30-45 g / L, temperature 40-50°C, current density 4-8 A / dm²; the treatment conditions for pickling are: sulfuric acid concentration 160-200 g / L, copper ion concentration 10-15 g / L, temperature 20-40°C.

[0012] Furthermore, the curing treatment conditions are: copper ion concentration 35-45 g / L, sulfuric acid concentration 120-150 g / L, temperature 45-60° C., and current density 15-35 A / dm².

[0013] Furthermore, the anti-oxidation treatment conditions are: zinc ion concentration 5.5-10.0 g / L, potassium pyrophosphate concentration 100-160 g / L, pH value 9-11, temperature 35-40°C, and current density 2-7 A / dm².

[0014] Furthermore, the passivation treatment conditions are: chromium ion concentration 1.5-6.5 g / L, pH value 8-11, temperature 20-25° C., and current density 3-7 A / dm².

[0015] Furthermore, the drying temperature is 150-230°C.

[0016] Beneficial Effects The present invention improves the copper nodule control treatment liquid, adds sodium thiopropane sulfonate (HP) and adjusts the copper ion concentration, cobalt ion concentration, sulfuric acid concentration and current density, so as to achieve a copper nodule diameter of ≤500nm and a surface area ratio of ≥1.08 on the treated surface, realizes small-size uniformity of the copper nodules, high surface area ratio and oxidation resistance after the surface treatment of the rolled copper foil, and stabilizes the color, so as to achieve the purpose of long-term preservation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the SEM image of the rolled copper foil after surface treatment in 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 rolled copper foil after surface treatment in Comparative Example 2. DETAILED DESCRIPTION

[0018] 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.

[0019] It should be noted that, in order to ensure the reliability of the verification results, the thickness of the copper foil in the embodiments of the present invention and the comparative examples is 35 μm, the copper foil processing speed is 20 m / min, and 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 (1) Electrolytic degreasing: sodium hydroxide 40g / L, temperature 45°C, current density 6A / dm²; (2) Pickling: sulfuric acid concentration 180g / L, copper ion concentration 15g / L, temperature 30°C; (3) Roughening: copper ion concentration 16 g / L, cobalt ion concentration 1.2 g / L, sodium thiopropane sulfonate (HP) concentration 80 mg / L, sulfuric acid concentration 220 g / L, temperature 25 °C, current density 20 A / dm²; (4) Curing: copper ion 40g / L, sulfuric acid concentration 140g / L, temperature 50°C, current density 20A / dm²; (5) Anti-oxidation: zinc ion concentration 8.0g / L, potassium pyrophosphate concentration 120g / L, pH value 10.0, temperature 35°C, current density 5A / dm²; (6) Passivation: chromium ion concentration 5.0g / L, pH value 9.5, temperature 25°C, current density 5A / dm²; (7) Drying: Dry at 180℃.

[0021] Example 2 (1) Electrolytic degreasing: sodium hydroxide 40g / L, temperature 45°C, current density 6A / dm²; (2) Pickling: sulfuric acid concentration 180g / L, copper ion concentration 15g / L, temperature 30°C; (3) Roughening: copper ion concentration 12 g / L, cobalt ion concentration 1.5 g / L, sodium thiopropane sulfonate (HP) concentration 120 mg / L, sulfuric acid concentration 220 g / L, temperature 25 °C, current density 20 A / dm²; (4) Curing: copper ion 40g / L, sulfuric acid concentration 140g / L, temperature 50°C, current density 20A / dm²; (5) Anti-oxidation: zinc ion concentration 8.0g / L, potassium pyrophosphate concentration 120g / L, pH value 10.0, temperature 35°C, current density 5A / dm²; (6) Passivation: chromium ion concentration 5.0g / L, pH value 9.5, temperature 25°C, current density 5A / dm²; (7) Drying: Dry at 180℃.

[0022] Example 3 (1) Electrolytic degreasing: sodium hydroxide 40g / L, temperature 45°C, current density 6A / dm²; (2) Pickling: sulfuric acid concentration 180g / L, copper ion concentration 15g / L, temperature 30°C; (3) Roughening: copper ion concentration 20g / L, cobalt ion concentration 0.5g / L, sodium thiopropane sulfonate (HP) concentration 60mg / L, sulfuric acid concentration 250g / L, temperature 25°C, current density 20A / dm²; (4) Curing: copper ion 40g / L, sulfuric acid concentration 140g / L, temperature 50°C, current density 20A / dm²; (5) Anti-oxidation: zinc ion concentration 8.0g / L, potassium pyrophosphate concentration 120g / L, pH value 10.0, temperature 35°C, current density 5A / dm²; (6) Passivation: chromium ion concentration 5.0g / L, pH value 9.5, temperature 25°C, current density 5A / dm²; (7) Drying: Dry at 180℃.

[0023] Comparative Example 1 Compared with Example 1, no cobalt ions were introduced into the coarsening seed in step (3) of Comparative Example 1, and the other conditions were the same as those in Example 1.

[0024] Comparative Example 2 Compared with Example 1, in step (3) of Comparative Example 2, sodium thiopropane sulfonate (HP) was not added to the coarsening seed, and the other conditions were the same as those in Example 1.

[0025] The rolled copper foil after surface treatment in Example 1 of the present invention is as follows Figure 1 As shown, the rolled copper foil after surface treatment in Comparative Example 1 is as follows Figure 2 As shown, the rolled copper foil after surface treatment in Comparative Example 2 is as follows Figure 3 As shown, the test results of the size and specific surface area of ​​the copper nodules of Examples 1 to 3, Comparative Example 1 and Comparative Example 2 are shown in Table 1 below: 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, neat directional arrangement, diameter ≤500nm, surface area ratio ≥1.09, and high peeling strength with PI. However, the rolled copper foils prepared by the surface treatment process in Comparative Examples 1 and 2 have a copper nodule diameter ≤1.2μm, a surface area ratio ≥1.02, low peeling strength, and defects such as loose bonding with PI, easy peeling, and etching residues. This shows that cobalt ions and sodium thiopropane sulfonate (HP) cooperate with each other and work together with other components to form small copper nodules that are tightly and evenly arranged on the surface of the copper foil. Due to its large specific surface area, it increases the contact area with the resin substrate and improves the peeling strength.

Claims

1. A copper nodule control additive for rolled copper foil, characterized in that: The composition comprises the following concentrations: copper ion: 10-20 g / L, cobalt ion: 0.1-1.5 g / L, sodium thiopropane sulfonate: 30-120 mg / L, sulfuric acid: 200-250 g / L.

2. The copper nodule control additive for rolled copper foil according to claim 1, characterized in that: The copper ions and cobalt ions are copper sulfate and cobalt sulfate.

3. The copper nodule control additive for rolled copper foil according to claim 1 or 2, characterized in that: The composition comprises the following concentrations: copper ion: 12-20 g / L, cobalt ion: 0.5-1.2 g / L, sodium thiopropane sulfonate: 60-120 mg / L, sulfuric acid: 220-250 g / L.

4. A method for surface treating a rolled copper foil using the rolled copper foil copper nodule control additive according to any one of claims 1 to 3, characterized in that: The copper foil after electrolytic degreasing and pickling is roughened with copper nodule control treatment liquid, the roughening treatment temperature is controlled at 20-30℃, the current density is 10-30A / dm², and the treated copper foil is sequentially cured, anti-oxidized, passivated and dried.

5. The method for surface treatment of rolled copper foil according to claim 4, characterized in that: The roughening treatment temperature is 25-28°C, and the current density is 15-25A / dm².

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

7. The method for roughening the surface of copper foil according to claim 4, characterized in that: The curing treatment conditions are: copper ion concentration 35-45g / L, sulfuric acid concentration 120-150g / L, temperature 45-60°C, current density 15-35A / dm².

8. The method for surface treatment of rolled copper foil according to claim 4, characterized in that: The anti-oxidation treatment conditions are: zinc ion concentration 5.5-10.0 g / L, potassium pyrophosphate concentration 100-160 g / L, pH value 9-11, temperature 35-40°C, current density 2-7 A / dm².

9. The method for surface treatment of rolled copper foil according to claim 4, characterized in that: The passivation treatment conditions are: chromium ion concentration 1.5 ~ 6.5g / L, pH value 8 ~ 11, temperature 20 ~ 25 ℃, current density 3 ~ 7A / dm².

10. The method for surface treatment of rolled copper foil according to claim 4, characterized in that: The drying temperature is 150~230℃.

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