Additive for low-profile electrolytic copper foil, preparation method, related product and application

Abstract

The invention belongs to the technical field of copper foil electrolysis additives, and relates to an additive for low-profile electrolytic copper foil, a preparation method, related products and application. The additive for the low-profile electrolytic copper foil is prepared from the following components: sodium 3, 3 '-dithiodipropane sulfonate, tetramethylene sulfoxide, 2-amino-4-sulfobutyric acid and a surfactant, wherein the surfactant is selected from at least one of PEG, PVA, PVP, PAA and PEI. According to the additive for the low-profile electrolytic copper foil, the surface roughness of the electrolytic copper foil can be effectively reduced, the glossiness is improved, and meanwhile the tensile property of the copper foil is not affected.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrolytic additives for copper foils, and relates to an additive for low-profile electrolytic copper foils, a preparation method, related products and applications. Background Art

[0002] Low-profile electrolytic copper foil is a metal material with special properties and is widely used in fields such as electronics and communication. The characteristics of low-profile electrolytic copper foil include: relatively thin thickness, usually between 1 - 10 μm; high surface flatness; good thermal and electrical conductivity, good plasticity, etc. Its specific application fields include high-density integrated circuits, flexible circuit boards, high-frequency microwave devices, high-frequency high-speed circuit boards, etc.

[0003] Electrolysis is an important process for preparing copper foils. The introduction of additives during the electrolysis process is an effective way to control the performance in the preparation process of electrolytic copper foils. The introduction of additives can change the reaction sites of copper deposition in the electrolytic system, thereby affecting the microstructure and morphology of the coating.

[0004] Traditional electrolytic copper foil additives are divided into two types: thiourea-type and mercapto sulfonate-type additives. Thiourea-type additives can improve the glossiness of copper foils and reduce surface roughness, but they will introduce sulfur elements into the copper foils, resulting in adverse effects such as an increase in the resistivity and brittleness of the copper foils. Mercapto sulfonate-type additives, including sodium polydithiopropane sulfonate (SPS) and sodium 3-mercapto-1-propane sulfonate (MPS), do not have the above problems. Through the mechanism of action of SPS and MPS during the electrolytic copper foil process, it can be found that electron transfer plays an important role in the process of copper atom deposition. It is generally believed that chloride ions play an important role in the process of electron transfer.

[0005] Chinese Patent CN102995086A provides an additive for producing low-profile electrolytic copper foils and a production process. This additive is composed of the following components mixed together: sodium 3-mercapto-1-propane sulfonate, 0.2 - 0.4 parts; polyethyleneimine alkyl salt or polyethyleneimine alkyl compound, 0.8 - 1.2 parts; polyethylene glycol 8000, 1 - 2 parts; N,N-diethylthiourea, 0.08 - 0.12 parts; pure water 20 parts. This additive and the copper foil produced using this additive can not only maintain low profile and low impedance, but also ensure a relatively high peel strength, and can be applicable to the production of both inner and outer layer circuits.

[0006] Chinese invention patent CN105274592A provides a three-component acidic bright copper plating additive and its applications in electroplating processes and electrolytic copper foil manufacturing processes. The additive includes 20 - 100 mg / L of chloride ions, 5 - 50 mg / L of organic propane sulfonate, and 10 - 80 mg / L of alkylphenol polyoxyethylene ether. It is used in a copper sulfate - sulfuric acid electrolyte system, where the copper ion content is 70 - 120 g / L and the sulfuric acid content is 80 - 150 g / L; the plating solution temperature is maintained at 40 - 70 °C and is in a stirred state. A current density of 600 - 900 mA / cm is applied to the cathode 2 , and by controlling the cathode rotation speed, a bright and leveling copper foil with the target thickness can be obtained. This additive can be used in high-temperature and high-concentration electrolytes, significantly improving the production efficiency of electrolytic copper foils; in addition, the components are simple and easy to regulate, and copper foils with various brightness levels from matte to mirror bright can be prepared under the condition of ensuring surface leveling, meeting the requirements of different applications.

[0007] Chinese invention patent CN111235605A provides an ultra-low profile electrolytic copper foil additive and a process for preparing electrolytic copper foils. The parts by weight of each component of the composite additive are: 1 - 10 parts of sodium polydithiopropane sulfonate, 0.5 - 5 parts of sodium 2-mercaptobenzimidazole propane sulfonate, and 2 - 20 parts of collagen. The types of components of this additive are few, the formulation is simple, the cost is relatively low, and it is convenient for on-site stable control. Using this additive, an ultra-low profile electrolytic copper foil with a roughness Rz ≤ 1 μm can be prepared. The performance indicators of the prepared electrolytic copper foil are: the thickness is 8 - 18 μm, the roughness Rz of the matte side of the copper foil ≤ 1 μm, the elongation rate ≥ 4%, and the tensile strength ≥ 33 Kgf / mm 2 , and the brightness is 300 - 600 unit gloss.

[0008] However, the prior art has not been able to provide a process for using sulfur-containing additives with multiple valence states to regulate the electron flow behavior, thereby obtaining a low-profile electrolytic copper foil with lower roughness, higher gloss, and no impact on the tensile strength. Summary of the Invention

[0009] In view of this, aiming at the problems of the above-mentioned prior art, the purpose of the present invention is to provide an additive for low-profile electrolytic copper foils, a preparation method, and its application in copper foil surface treatment. By compounding three sulfur-containing components, namely sodium polydithiopropane sulfonate, tetramethylene sulfoxide, and 2-amino-4-sulfobutyric acid, especially by introducing the sulfur-containing organic compound tetramethylene sulfoxide with an intermediate valence state to regulate the microscopic process of electron flow during electrolysis, the deposition rate of copper ions is neither too fast (resulting in the formation of crystal nuclei and an increase in roughness) nor too slow (making the reaction difficult to proceed), thereby effectively reducing the roughness of the obtained electrolytic copper foil, enhancing the gloss, and having no impact on the mechanical properties.

[0010] To achieve the above-mentioned invention object, on the one hand, the present invention provides an additive for low-profile electrolytic copper foil, which comprises the following components:

[0011] Sodium polydithiopropane sulfonate, tetramethylene sulfoxide, 2-amino-4-sulfobutyric acid and a surfactant;

[0012] Wherein, the surfactant is selected from at least one of PEG (polyethylene glycol), PVA (polyvinyl alcohol), PVP (polyvinylpyrrolidone), PAA (polyacrylic acid), and PEI (polyethyleneimine).

[0013] Preferably, the surfactant is at least one of PEG and PEI.

[0014] More preferably, the surfactant is a mixture of PEG and PEI.

[0015] Still more preferably, the weight ratio of PEG to PEI in the mixture is 1.5 - 4:1.

[0016] Further preferably, and as an embodiment of the present invention, the ratio of PEG to PEI is 3:1.

[0017] Preferably, the number-average molecular weight of the PEG is 400 - 800, and more preferably 400.

[0018] Preferably, the PEI is branched PEI.

[0019] Preferably, the weight-average molecular weight of the PEI is 300 - 1200, and more preferably 300.

[0020] Preferably, the additive for low-profile electrolytic copper foil comprises the following components by weight: 8 - 20 parts of sodium polydithiopropane sulfonate, 3 - 7 parts of tetramethylene sulfoxide, 4 - 8 parts of 2-amino-4-sulfobutyric acid, and 37 - 43 parts of a surfactant.

[0021] More preferably, the additive for low-profile electrolytic copper foil comprises the following components by weight: 11 - 17 parts of sodium polydithiopropane sulfonate, 4 - 6 parts of tetramethylene sulfoxide, 5 - 7 parts of 2-amino-4-sulfobutyric acid, and 40 parts of a surfactant.

[0022] Still more preferably, the additive for low-profile electrolytic copper foil comprises the following components by weight: 14 parts of sodium polydithiopropane sulfonate, 5 parts of tetramethylene sulfoxide, 6 parts of 2-amino-4-sulfobutyric acid, and 40 parts of a surfactant.

[0023] On the other hand, the present invention provides a copper sulfate electrolyte solution, and the components of the copper sulfate electrolyte solution include the above-mentioned additive for low-profile electrolytic copper foil.

[0024] Preferably, the copper sulfate electrolyte consists of the following components:

[0025] Additives for low-profile electrolytic copper foil, copper sulfate, sulfuric acid, a chloride ion source, and water.

[0026] Preferably, the chloride ion source is selected from at least one of hydrogen chloride, sodium chloride, and potassium chloride.

[0027] Preferably, the concentration of the additives for low-profile electrolytic copper foil in the copper sulfate electrolyte is 0.1 - 1 g / L; the concentration of copper ions in the copper sulfate electrolyte is 50 - 150 g / L, the concentration of sulfuric acid in the copper sulfate electrolyte is 60 - 160 g / L, and the concentration of chloride ions in the copper sulfate electrolyte is 0.001 - 0.1 g / L.

[0028] On the other hand, the present invention provides a method for preparing a copper sulfate electrolyte, comprising the following steps:

[0029] Mix copper sulfate, sulfuric acid, a chloride ion source, and water, adjust the temperature, add additives for low-profile electrolytic copper foil, and mix evenly to obtain the product.

[0030] On the other hand, the present invention provides the use of the above-mentioned additives for low-profile electrolytic copper foil or the above-mentioned copper sulfate electrolyte in the preparation of copper foil.

[0031] On the other hand, the present invention provides a process for surface-treating copper foil using the above-mentioned copper sulfate electrolyte, comprising the following steps:

[0032] Introduce the copper sulfate electrolyte into an electrolytic cell, adjust the temperature to 45 - 60 °C, and the current density to 55 - 75 A / dm 2 , and perform electrolytic treatment on the base copper foil to obtain the surface-treated copper foil.

[0033] Preferably, the time for the electrolytic treatment is 10 - 15 min.

[0034] On the other hand, the present invention provides the electrolytic copper foil prepared by the above process.

[0035] On the other hand, the present invention provides a copper-clad laminate, which comprises the above-mentioned electrolytic copper foil.

[0036] On the other hand, the present invention provides a printed wiring board, which comprises the above-mentioned electrolytic copper foil.

[0037] On the other hand, the present invention provides a method for manufacturing a printed wiring board, which is prepared using the above-mentioned electrolytic copper foil.

[0038] Preferably, the method for manufacturing the printed wiring board includes the following steps: laminating the above electrolytic copper foil and the insulating substrate to form a copper-clad laminate, and then forming a circuit by any one of the semi-additive method, subtractive method, partial additive method, or modified semi-additive method.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The present invention provides an additive for low-profile electrolytic copper foil, which is compounded with three sulfur-containing components, namely sodium polydithiopropane sulfonate, tetramethylene sulfoxide, and 2-amino-4-sulfobutyric acid. In particular, by introducing a sulfur-containing organic compound with an intermediate valence state, tetramethylene sulfoxide, the microscopic process of electron flow during electrolysis is regulated, so that the deposition rate of copper ions is neither too fast nor too slow, thereby effectively reducing the surface roughness of the electrolytic copper foil, improving the gloss, and at the same time not affecting the tensile properties of the copper foil. Detailed implementation manners

[0041] Terms and statements of the present invention:

[0042] 1. Articles "a", "an", and "the": Unless otherwise explicitly limited to one (kind) of object, they include plural objects.

[0043] 2. Numerical ranges: Unless otherwise explicitly indicated, all ranges or ratios disclosed herein will be understood to include any and all sub-ranges or sub-ratios contained therein. For example, the stated range or ratio of 1 to 30 should be considered to include any sub-range or sub-ratio, integer, decimal, or sub-range or sub-ratio composed of integers or decimals between the minimum value of 1 and the maximum value of 30, including the endpoints.

[0044] The following non-limiting examples can enable those of ordinary skill in the art to more comprehensively understand the present invention, but do not limit the present invention in any way. The following content is only an exemplary illustration of the scope claimed by the present invention. Those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and they should also fall within the scope claimed by the present invention.

[0045] The present invention will be further described below by way of specific examples. All kinds of chemical reagents used in the examples of the present invention are obtained through conventional commercial channels unless otherwise specified. Unless otherwise specified, the contents described below are mass contents. Unless otherwise specified, it is understood to be carried out at room temperature.

[0046] In the following examples, the sources of some reagents are as shown in Table 1 below:

[0047] Table 1

[0048]

[0049]

[0050] Examples 1 - 5 provide an additive for low-profile electrolytic copper foil, and the components are shown in Table 2 (unit: g).

[0051] Table 2

[0052]

[0053] In Table 2, the number-average molecular weight of the PEG used is 400, and the weight-average molecular weight of the PEI used is 300.

[0054] Comparative Examples 1 - 6 provide an additive for low-profile electrolytic copper foil, and the components are shown in Table 3 (unit: g, "-" indicates that the component is not contained).

[0055] Table 3

[0056]

[0057] In Table 3, the number-average molecular weight of the PEG used is 400, and the weight-average molecular weight of the PEI used is 300.

[0058] Example 6

[0059] Compared with Example 1, the PEG with a number-average molecular weight of 400 is replaced with an equal weight of PEG with a number-average molecular weight of 300, and the rest are the same.

[0060] Example 7

[0061] Compared with Example 1, the PEG with a number-average molecular weight of 400 is replaced with an equal weight of PEG with a number-average molecular weight of 2000, and the rest are the same.

[0062] Example 8

[0063] Compared with Example 1, the PEG with a number-average molecular weight of 400 is replaced with an equal weight of PEG with a number-average molecular weight of 20000, and the rest are the same.

[0064] Example 9

[0065] Compared with Example 1, the PEI with a weight-average molecular weight of 300 is replaced with an equal weight of PEI with a weight-average molecular weight of 1800, and the rest are the same.

[0066] Example 10

[0067] Compared with Example 1, the PEI with a weight-average molecular weight of 300 is replaced with an equal weight of PEI with a weight-average molecular weight of 10000, and the rest are the same.

[0068] Example 11

[0069] Configuration of a copper sulfate electrolyte

[0070] Pour sulfuric acid (98%) into deionized water to prepare a 20% sulfuric acid solution. Weigh 550 g of the 20% sulfuric acid solution, add 82.4 mg of sodium chloride and 392.89 g of copper sulfate pentahydrate, and stir to dissolve. During the dissolution process, control the solution temperature ≤ 50 °C. After complete dissolution, add 1 g of an additive for low-profile electrolytic copper foil, and make up the volume to 1 L to obtain the copper sulfate electrolyte. In this copper sulfate electrolyte, the chloride ion concentration is 0.05 g / L, the sulfuric acid concentration is 110 g / L, the copper ion concentration is 100 g / L, and the concentration of the additive for low-profile electrolytic copper foil is 1 g / L.

[0071] Using the additives for low-profile electrolytic copper foil prepared in Examples 1 - 10 and Comparative Examples 1 - 6 respectively, the obtained copper sulfate electrolytes are denoted as Electrolyte Example 1 - Electrolyte Example 10 and Electrolyte Comparative Example 1 - Electrolyte Comparative Example 6 in sequence.

[0072] Example 12

[0073] A preparation process of electrolytic copper foil

[0074] Pour the copper sulfate electrolyte into an electrolytic cell, adjust the temperature to 50 °C, and the current density is 65 A / dm 2 . Rotate the titanium cathode roller and carry out electrolysis treatment to obtain electrolytic copper foil. By adjusting the rotation speed of the titanium cathode roller, the thickness of the electrolytic copper foil can be controlled. In this example, the thickness of the electrolytic copper foil is 150 μm.

[0075] Using Electrolyte Example 1 - Electrolyte Example 10 and Electrolyte Comparative Example 1 - Electrolyte Comparative Example 6 to prepare electrolytic copper foil in sequence, the obtained electrolytic copper foils are denoted as Electrolytic Copper Foil Example 1 - Electrolytic Copper Foil Example 10 and Electrolytic Copper Foil Comparative Example 1 - Electrolytic Copper Foil Comparative Example 6 in sequence.

[0076] In accordance with the existing technology and standards, test the technical indicators of Electrolytic Copper Foil Example 1 - Electrolytic Copper Foil Example 10 and Electrolytic Copper Foil Comparative Example 1 - Electrolytic Copper Foil Comparative Example 6 themselves, including the surface roughness Rz of the matte side, the surface roughness Ra of the matte side, tensile strength, elongation rate, and glossiness.

[0077] The test results of the surface roughness Rz of the matte side, the surface roughness Ra of the matte side, and glossiness are shown in Table 4.

[0078] Table 4

[0079]

[0080]

[0081] It can be seen that, compared with the electrolytic copper foil comparative examples, the roughness of the lamination surface, the roughness of the non-lamination surface, and the glossiness of the electrolytic copper foil examples are more excellent.

[0082] The test results of the tensile strength and elongation are shown in Table 5.

[0083] Table 5

[0084]

[0085] It can be seen that, compared with the electrolytic copper foil comparative examples, the tensile strength, elongation, and peel strength of the electrolytic copper foil examples are not significantly reduced.

[0086] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than a limitation on the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solution of the present invention by those of ordinary skill in the art shall not depart from the essence and scope of the technical solution of the present invention.

Claims

1. An additive for low-profile electrolytic copper foil, characterized in that: Includes the following ingredients: Sodium poly(dipropylene glycol disulfide), tetramethylene sulfoxide, 2-amino-4-sulfobutyric acid and a surfactant; Wherein, the surfactant is selected from at least one of PEG, PVA, PVP, PAA and PEI.

2. The additive for low-profile electrolytic copper foil according to claim 1, characterized in that: The surfactant is at least one of PEG and PEI.

3. The additive for low-profile electrolytic copper foil according to claim 1, characterized in that: The invention comprises the following ingredients by weight: 8-20 parts of sodium polydipropane disulfide sulfonate, 3-7 parts of tetramethylene sulfoxide, 4-8 parts of 2-amino-4-sulfobutyric acid and 37-43 parts of surfactant.

4. The additive for low-profile electrolytic copper foil according to claim 3, characterized in that: The invention comprises the following ingredients by weight: 11-17 parts of sodium polydipropane disulfide sulfonate, 4-6 parts of tetramethylene sulfoxide, 5-7 parts of 2-amino-4-sulfobutyric acid and 40 parts of a surfactant.

5. The additive for low-profile electrolytic copper foil according to claim 4, characterized in that: The invention comprises the following ingredients by weight: 14 parts of sodium polydipropane disulfide sulfonate, 5 parts of tetramethylene sulfoxide, 6 parts of 2-amino-4-sulfobutyric acid and 40 parts of a surfactant.

6. A copper sulfate electrolyte, characterized in that: The composition of the copper sulfate electrolyte includes the additive for low-profile electrolytic copper foil according to any one of claims 1 to 5.

7. The copper sulfate electrolyte according to claim 6, characterized in that The copper sulfate electrolyte consists of the following components: an additive for low-profile electrolytic copper foil, copper sulfate, sulfuric acid, a chloride ion source and water.

8. The copper sulfate electrolyte according to claim 7, characterized in that The chloride ion source is selected from at least one of hydrogen chloride, sodium chloride and potassium chloride.

9. The copper sulfate electrolyte according to claim 7, characterized in that: The concentration of the additive for low-profile electrolytic copper foil in the copper sulfate electrolyte is 0.1-1 g / L; the concentration of the copper ions in the copper sulfate electrolyte is 50-150 g / L, the concentration of the sulfuric acid in the copper sulfate electrolyte is 60-160 g / L, and the concentration of the chloride ions in the copper sulfate electrolyte is 0.001-0.1 g / L.

10. The method for preparing the copper sulfate electrolyte according to any one of claims 6 to 9, characterized in that: The method comprises the following steps: mixing copper sulfate, sulfuric acid, a chloride ion source and water, adjusting the temperature, adding an additive for low-profile electrolytic copper foil, and mixing well to obtain the product.

11. Use of the additive for low-profile electrolytic copper foil according to any one of claims 1 to 5 or the copper sulfate electrolyte according to any one of claims 6 to 9 in the preparation of copper foil.

12. A process for preparing electrolytic copper foil, characterized in that: The following steps are involved: Introduce copper sulfate electrolyte into the electrolytic cell, adjust the temperature to 45-60℃, and the current density to 55-75A / dm 2 , rotating the titanium cathode roller, electrolyzing, and obtaining electrolytic copper foil; Wherein, the copper sulfate electrolyte is the copper sulfate electrolyte described in any one of claims 6-9.

13. The electrolytic copper foil obtained by the process of claim 12.

14. A copper-clad laminate, characterized in that: Comprising the electrolytic copper foil as claimed in claim 13.

15. A printed wiring board, characterized in that: Prepared using the electrolytic copper foil described in claim 13.

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