A micro-roughening process for generating needle-shaped polyhedrons on the surface of electrolytic copper foil

Abstract

This invention relates to a micro-roughening process for generating needle-like polyhedrons on the surface of electrolytic copper foil. The process first involves acid washing the electrolytic copper foil to obtain a pretreated foil. Then, a micro-roughening electrolyte is prepared, followed by micro-roughening treatment. Specifically, the micro-roughening electrolyte is transferred to an electrolytic cell, and the pretreated copper foil is used as the anode for electrolysis. After the reaction, the copper foil is cleaned and dried, resulting in an electrolytic copper foil with needle-like polyhedrons on its surface. The electrolyte is a clear solution obtained by adding NaOH and K₂S₂O₈ to deionized water and stirring. The advantages of this invention are its simplicity, low cost, lack of harm to humans, and environmental friendliness. It produces an electrolytic copper foil with needle-like polyhedrons on its surface, resolving the contradiction between low roughness and high peel strength, and achieving a synergistic improvement in both.

Description

Technical Field

[0001] This invention relates to the field of electrolytic copper foil surface treatment technology, specifically to a micro-roughening process for generating needle-like polyhedra on the surface of electrolytic copper foil. Background Technology

[0002] Electrolytic copper foil is widely used in high-tech fields such as chip packaging, copper-clad laminates (CCL), printed circuit boards (PCB), advanced driver assistance systems (ADAS) in automobiles, and internet data centers (IDC). It is known as the "neural network" for signal transmission and communication in electronic products and is a key basic material for packaging substrates, PCBs, and lithium battery current collectors. With the rapid development of 5G communication technology, IoT and internet technology, cloud storage and computing, and other fields, electronic products are becoming increasingly miniaturized, lightweight, thin, intelligent, and multifunctional, placing more stringent requirements on the comprehensive performance of electrolytic copper foil. For example, high-performance lithium battery electrolytic copper foil not only needs to be free of pinholes and wrinkles on the surface but also needs to have high tensile strength and elongation. For electrolytic copper foil used in chip packaging, low surface roughness is required to reduce signal loss, while high peel strength is needed to ensure the integrity and reliability of signal transmission. Therefore, electrolytic copper foil for chip packaging needs to simultaneously achieve low profile and high peel strength. Research in my country's copper foil industry started relatively late, and breakthroughs have not yet been made in the production technology and equipment manufacturing of high-performance electrolytic copper foil. The process technology for producing high-performance electrolytic copper foil needs to be further improved, especially the micro-roughening technology that achieves coordinated improvement in low roughness and high peel strength of electrolytic copper foil.

[0003] Chinese patent ZL202111645336.X discloses a roughening treatment solution and a roughening treatment process for the surface of copper foil. The process adopts a two-step electrodeposition step, and the solution used in each electrodeposition step is different. Some steps also require heating, so the process is relatively complex. Finally, a fine copper nodule layer morphology is formed on the surface of the copper foil.

[0004] Chinese patent ZL201910489068.3 discloses a micro-roughening process for the surface of electrolytic copper foil. The process involves cleaning the original electrolytic copper foil in dilute sulfuric acid, then placing the cleaned copper foil in an electrolyte solution for electrolytic roughening. Next, a copper foil film is deposited onto the roughened surface of the copper foil using electrodeposition to reinforce the roughness. The copper foil is then placed in an electrolyte solution for weak roughening electrolytic treatment to plate a zinc-nickel alloy, followed by anti-oxidation treatment and spraying with a silane coupling agent. Finally, the copper foil is dried in a drying oven. This process is complex, and the sodium dichromate and other substances in the zinc-nickel alloy plating electrolyte are toxic, posing a threat to human health and environmental pollution. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a micro-roughening process for generating needle-like polyhedra on the surface of electrolytic copper foil. By using this method to treat electrolytic copper foil, needle-like polyhedra can be generated on the surface of the electrolytic copper foil, thereby achieving micro-roughening of the surface of the electrolytic copper foil, improving the peel strength of the electrolytic copper foil, and the process is simple, low-cost, and environmentally friendly.

[0006] To achieve the above objectives, this invention discloses a micro-roughening process for generating needle-like polyhedra on the surface of electrolytic copper foil, comprising the following steps:

[0007] (1) Pretreatment: The electrolytic copper foil is immersed in a dilute sulfuric acid solution for acid washing to obtain pretreated electrolytic copper foil;

[0008] (2) Preparation of micro-coarsened electrolyte: A certain mass of NaOH and K2S2O8 are added to deionized water and stirred to obtain a clear solution, which is the micro-coarsened electrolyte;

[0009] (3) Micro-roughening treatment: First, transfer the micro-roughened electrolyte obtained in step (2) into the electrolytic cell, and then use the pretreated electrolytic copper foil obtained in step (1) as the anode and the industrial pure titanium sheet as the cathode. A constant current is passed through to carry out the electrolytic reaction. After the reaction is completed, the electrolytic copper foil is first washed with deionized water 3 times, and then dried at 50°C for 5 minutes. After drying, an electrolytic copper foil with needle-like polyhedrons on the surface is obtained.

[0010] Furthermore, the thickness of the electrolytic copper foil in step (1) is 18 μm.

[0011] Furthermore, in step (1), the mass fraction of dilute sulfuric acid is 10%, and the pickling time is 3-5 seconds. The purpose of the pretreatment in step (1) is to remove oxides from the surface of the electrolytic copper foil.

[0012] Furthermore, in step (2), the concentration of NaOH in the electrolyte is 80-120 g / L, and the concentration of K2S2O8 is 20-40 g / L.

[0013] Furthermore, in step (3), the electrolysis temperature is 25°C, and the constant current density is 0.5–2 A / dm³. 2 The reaction time is 6–12 seconds.

[0014] The present invention also aims to provide an electrolytic copper foil with needle-like polyhedrons on its surface obtained by the above-described micro-roughening process, and the application of the electrolytic copper foil in CCL and PCB.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The process provided by the present invention is relatively simple, low in cost, harmless to the human body and does not pollute the environment.

[0017] (2) The process provided by this invention can generate needle-like polyhedra on the surface of electrolytic copper foil, which can not only increase the specific surface area of ​​electrolytic copper foil, but also enhance the bonding and anchoring force between electrolytic copper foil and FR-4 prepreg, thereby improving the peel strength of electrolytic copper foil. In addition, this process can also reduce the surface roughness of electrolytic copper foil, achieving a synergistic improvement in low roughness and high peel strength, ensuring the integrity and reliability of high-frequency and high-speed signal transmission. Attached Figure Description

[0018] Figure 1 The image shows a surface SEM image of an 18 μm thick electrolytic copper foil before pretreatment.

[0019] Figure 2 This is a surface SEM image of the electrolytic copper foil prepared in Example 2 after fine roughening treatment. Detailed Implementation

[0020] To better understand the content of this invention, it will be further described below with reference to specific embodiments and accompanying drawings. The following embodiments are based on the technology of this invention and provide detailed implementation methods and operating steps, but the scope of protection of this invention is not limited to the following embodiments.

[0021] Example 1:

[0022] (1) Pretreatment: Immerse an 18μm thick electrolytic copper foil in a 10% (w / w) dilute sulfuric acid solution for 3-5 seconds to obtain a pretreated electrolytic copper foil;

[0023] (2) Preparation of micro-coarsened electrolyte: A certain mass of NaOH and K2S2O8 are added to deionized water and stirred to obtain a clear solution. The concentration of NaOH in the solution is 95 g / L and the concentration of K2S2O8 is 30 g / L. This solution is the micro-coarsened electrolyte.

[0024] (3) Fine-graining treatment: First, the fine-grained electrolyte obtained in step (2) is transferred to the electrolytic cell. Then, the pretreated electrolytic copper foil obtained in step (1) is used as the anode, and the industrial pure titanium sheet is used as the cathode. A constant current is passed through to carry out the electrolytic reaction, with a current density of 1.2 A / dm³. 2 The electrolysis temperature was 25℃ and the electrolysis reaction time was 12s. After the reaction was completed, the electrolytic copper foil was first washed with deionized water 3 times, and then dried at 50℃ for 5min. After drying, an electrolytic copper foil with needle-like polyhedrons on the surface was obtained.

[0025] The electrolytic copper foil with needle-like polyhedrons on the surface was finally laminated with FR-4 prepreg, and the peel strength of the electrolytic copper foil was tested using an MK-BL-X 90-degree peel strength tester.

[0026] Example 2:

[0027] (1) Pretreatment: Immerse an 18μm thick electrolytic copper foil in a 10% (w / w) dilute sulfuric acid solution for 3-5 seconds to obtain a pretreated electrolytic copper foil;

[0028] (2) Preparation of micro-coarsened electrolyte: A certain mass of NaOH and K2S2O8 are added to deionized water and stirred to obtain a clear solution. The concentration of NaOH in the solution is 80 g / L and the concentration of K2S2O8 is 20 g / L. This solution is the micro-coarsened electrolyte.

[0029] (3) Fine-graining treatment: First, the fine-grained electrolyte obtained in step (2) is transferred to the electrolytic cell. Then, the pretreated electrolytic copper foil obtained in step (1) is used as the anode, and the industrial pure titanium sheet is used as the cathode. A constant current is passed through to carry out the electrolytic reaction, with a current density of 1.2 A / dm³. 2 The electrolysis temperature was 25℃ and the electrolysis reaction time was 6s. After the reaction was completed, the electrolytic copper foil was first washed with deionized water 3 times, and then dried at 50℃ for 5min. After drying, an electrolytic copper foil with needle-like polyhedrons on the surface was obtained.

[0030] The electrolytic copper foil with needle-like polyhedrons on the surface was finally laminated with FR-4 prepreg, and the peel strength of the electrolytic copper foil was tested using an MK-BL-X 90-degree peel strength tester.

[0031] Figure 1 This is a surface SEM image of an 18 μm thick electrolytic copper foil before pretreatment. Figure 2 This is a surface SEM image of the electrolytic copper foil prepared in this embodiment after micro-roughening treatment. As can be seen from the image, after micro-roughening treatment, needle-like polyhedra with diameters of tens to hundreds of nanometers are generated on the surface of the electrolytic copper foil.

[0032] Example 3:

[0033] (1) Pretreatment: Immerse an 18μm thick electrolytic copper foil in a 10% (w / w) dilute sulfuric acid solution for 3-5 seconds to obtain a pretreated electrolytic copper foil;

[0034] (2) Preparation of micro-coarsened electrolyte: A certain mass of NaOH and K2S2O8 are added to deionized water and stirred to obtain a clear solution. The concentration of NaOH in the solution is 110 g / L and the concentration of K2S2O8 is 35 g / L. This solution is the micro-coarsened electrolyte.

[0035] (3) Fine-graining treatment: First, the fine-grained electrolyte obtained in step (2) is transferred to the electrolytic cell. Then, the pretreated electrolytic copper foil obtained in step (1) is used as the anode, and the industrial pure titanium sheet is used as the cathode. A constant current is passed through to carry out the electrolytic reaction, with a current density of 0.5 A / dm³. 2 The electrolysis temperature was 25℃ and the electrolysis reaction time was 6s. After the reaction was completed, the electrolytic copper foil was first washed with deionized water 3 times, and then dried at 50℃ for 5min. After drying, an electrolytic copper foil with needle-like polyhedrons on the surface was obtained.

[0036] The electrolytic copper foil with needle-like polyhedrons on the surface was finally laminated with FR-4 prepreg, and the peel strength of the electrolytic copper foil was tested using an MK-BL-X 90-degree peel strength tester.

[0037] Comparative Example 1

[0038] (1) Pretreatment: Immerse the 18μm electrolytic copper foil in a 10% dilute sulfuric acid solution for 3-5 seconds to obtain the pretreated electrolytic copper foil;

[0039] (2) The pretreated electrolytic copper foil obtained in step (1) is first washed with deionized water 3 times, and then dried at 50°C for 5 minutes. After drying, the electrolytic copper foil without micro-roughening treatment is obtained.

[0040] The electrolytic copper foil without micro-roughening treatment was pressed together with FR-4 prepreg, and the peel strength of the electrolytic copper foil was tested.

[0041] The surface roughness of the electrolytic copper foil before micro-roughening in Examples 1-3 (i.e., the electrolytic copper foil before pretreatment), the electrolytic copper foil before pretreatment in Comparative Example 1, and the electrolytic copper foil with needle-like polyhedrons formed on the surface after micro-roughening treatment in Examples 1-3 were tested using a JD-520 surface roughness tester.

[0042] The obtained surface roughness and peel strength values ​​are shown in Table 1.

[0043] Table 1. Surface roughness and peel strength of electrolytic copper foil before and after micro-roughening.

[0044]

[0045] As shown in Table 1, after micro-roughening treatment, not only can the surface roughness Rz value of electrolytic copper foil be reduced, but the peel strength of electrolytic copper foil after micro-roughening treatment can also be increased by about 0.3 N / mm compared with electrolytic copper foil without micro-roughening treatment, which is about 5-6 times higher.

[0046] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A micro-roughening process for generating needle-like polyhedra on the surface of electrolytic copper foil, characterized in that... Specifically, the following steps are included: (1) Pretreatment: The electrolytic copper foil is immersed in a dilute sulfuric acid solution for acid washing to obtain pretreated electrolytic copper foil; (2) Preparation of micro-coarsened electrolyte: Add a certain mass of NaOH and K2S2O8 to deionized water and stir to obtain a clear solution. This solution is the micro-coarsened electrolyte, wherein the concentration of NaOH is 80~120g / L and the concentration of K2S2O8 is 20~40g / L. (3) Micro-roughening treatment: the micro-roughening electrolyte obtained in step (2) is transferred into an electrolytic cell, the pretreated electrolytic copper foil obtained in step (1) is used as an anode, and an industrial pure titanium sheet is used as a cathode, a constant current with a current density of 0.5-2 A / dm 2 is introduced to perform an electrolytic reaction, the reaction time is 6-12 s, after the reaction, the electrolytic copper foil is washed with deionized water for 3 times, and then dried at 50°C for 5 min, and the electrolytic copper foil with needle-shaped polyhedron generated on the surface is obtained after drying.

2. The micro-roughening process for generating needle-like polyhedra on the surface of electrolytic copper foil as described in claim 1, characterized in that: The thickness of the electrolytic copper foil in step (1) is 18 μm.

3. The micro-roughening process for generating needle-like polyhedra on the surface of electrolytic copper foil as described in claim 1, characterized in that: In step (1), the mass fraction of dilute sulfuric acid is 10%, and the pickling time is 3~5s.

4. The micro-roughening process for generating needle-like polyhedra on the surface of electrolytic copper foil as described in claim 1, characterized in that: The electrolysis temperature in step (3) is 25°C.

5. Electrolytic copper foil with needle-like polyhedral surfaces obtained by the micro-roughening process as described in any one of claims 1 to 4.

6. The application of the electrolytic copper foil with needle-like polyhedrons formed on the surface as described in claim 5 in CCL and PCB.

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