Chemical copper plating solution and preparation method thereof

Abstract

The invention discloses a chemical copper plating solution and a preparation method thereof, and belongs to the technical field of chemical copper plating processes, and the chemical copper plating solution is formed by mixing a copper plating solution A, a copper plating solution B, a copper plating solution C and a copper plating solution D according to a preset proportion. In addition, the invention also discloses a method for preparing the chemical copper plating solution, which comprises the following steps of: adding 16 parts of CuSO4. 5H2O and 0.012 part of additive H into every 1000 parts of solution to prepare a copper plating solution A, and adding 12 parts of potassium sodium tartrate, 12 parts of ethylene diamine tetraacetic acid and 0.022 part of additive X into every 1000 parts of solution to prepare a copper plating solution B, 12 parts of NaOH is added into every 1000 parts of solution to prepare a copper plating C solution; the copper plating liquid D is 37% formaldehyde; and mixing the components. Therefore, the technical problems that in the prior art, the chemical copper plating deposition rate is low, the plating solution stability is poor, and the plating layer quality is unqualified due to the fact that formaldehyde is omitted can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical copper plating technology, in particular to a chemical copper plating solution and a preparation method thereof. Background Art

[0002] Copper plating is a technology that deposits a layer of copper on the metal surface through an electrochemical process. Currently, this technology is widely used in circuit board manufacturing and is often referred to as copper plating or pore plating in the industry. This is a self-catalytic redox reaction. Specifically, copper plating mainly uses electrochemical principles to attach a layer of copper to the metal surface by electrolysis. In the copper plating process, an electrolyte containing copper ions, such as a copper sulfate solution, is usually used. When current passes through, copper ions are attracted to the cathode, that is, the metal to be plated, and are reduced to metallic copper on it, thereby depositing on the metal surface to form a copper film.

[0003] Chemical copper plating liquid is a special liquid used in chemical copper plating process. It has the ability to deposit copper at a high speed and can form a copper coating of a certain thickness in a short time. This type of copper plating liquid can maintain stable performance during the working process and is not easy to decompose or deteriorate. It can also be used for copper plating on various metal and non-metal surfaces, such as iron, steel, stainless steel, zinc alloy, copper alloy, and non-metal materials such as ceramics, glass, resin, plastic, etc., so that the coating is uniform and dense, has strong bonding with the substrate, and has good corrosion resistance and conductivity.

[0004] Usually, chemical copper plating solution is mainly composed of copper salt solution, regulator, such as acidic regulator, surfactant and stabilizer, etc. Among them, copper salt solution provides copper ions, regulator is used to adjust the pH value and copper deposition speed of plating solution, surfactant helps to improve the uniformity and adhesion of plating layer, and stabilizer is used to prevent decomposition of plating solution and occurrence of side reactions.

[0005] Based on this, Chinese patent CN104141120B discloses a method for preparing and using a monovalent copper chemical copper plating solution; the monovalent copper chemical copper plating solution contains components such as cuprous chloride, potassium chloride, ammonia water, auxiliary complexing agent, formaldehyde, stabilizer and antioxidant, and needs to be heated to 40-70°C and loaded with 0.2-4.0 dm2 / L when used. The monovalent copper chemical copper plating solution can deposit more metallic copper while consuming an equivalent amount of formaldehyde, which can not only increase the plating speed of chemical copper plating, but also save the amount of formaldehyde used, which is conducive to improving production efficiency and controlling production costs.

[0006] However, the chemical copper plating solution disclosed in the prior art still has technical problems that affect the deposition rate of chemical copper plating, the stability of the plating solution and the quality of the coating. Specifically, in the prior art, most chemical copper plating solutions are composed of a main salt, a complexing agent, an additive and a reducing agent, and formaldehyde is the most common reducing agent in chemical copper plating solutions because it has excellent reducing ability and can reduce divalent copper ions to metallic copper under alkaline conditions. Therefore, most of the reducing agents formaldehyde on the market are mixed with the main salt copper sulfate to form the main plating solution A for chemical copper plating and used in the chemical copper plating process. However, formaldehyde has a strong irritating effect on the skin and eyes and is carcinogenic to the human body; at the same time, the chemical copper plating system using formaldehyde as a reducing agent has the advantages of low cost, high coating purity, and good conductivity. Therefore, when a suitable reducing agent has not been found to replace formaldehyde, the formaldehyde is separated from the main plating solution and directly added as an independent reducing agent in the chemical copper plating process to reduce the harm to the human body caused by the strong irritating odor generated by formaldehyde during the stirring process when preparing the main plating solution A. In such a technical solution, the separation of the reducing agent formaldehyde will have a great impact on the deposition rate of chemical copper plating, the stability of the plating solution and the quality of the coating. Summary of the invention

[0007] Based on this, it is necessary to provide a chemical copper plating solution and a preparation method thereof in order to optimize the technical issues such as the deposition rate of chemical copper plating, the stability of the plating solution and the quality of the coating.

[0008] A chemical copper plating solution is composed of copper plating solution A, copper plating solution B, copper plating solution C and copper plating solution D mixed in a preset ratio.

[0009] Specifically, in parts by mass, the copper plating solution A is: 16 parts of CuSO4·5H2O and 0.012 parts of additive H are added to every 1000 parts of the solution; the remainder is pure water or distilled water.

[0010] Specifically, in parts by mass, the copper plating solution B is: 12 parts of potassium sodium tartrate, 12 parts of disodium ethylenediaminetetraacetate and 0.022 parts of additive X are added to every 1000 parts of the solution; the remainder is pure water or distilled water.

[0011] Specifically, in parts by mass, the copper plating solution C is: 12 parts of NaOH are added to every 1000 parts of the solution, and the remainder is pure water or distilled water.

[0012] Specifically, copper plating solution D is 37% formaldehyde.

[0013] Specifically, the proportions of the components are as follows, by mass: 10 parts of copper plating solution A, 12 to 15 parts of copper plating solution B, 10 to 15 parts of copper plating solution C, and 1.2 parts of copper plating solution D.

[0014] Specifically, the additive H is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polyethylene glycol, polyethyleneimine or sodium dodecyl alcohol polyoxyethylene ether sulfate.

[0015] Specifically, the additive X is at least one of polyvinyl pyrrolidone, an organic sulfur compound, potassium ferrocyanide, bipyridine, thioglycolic acid, phenylcyclotetrazolyl, N-phenylnaphthalenesulfonamide or sodium propylene oxide sulfonate.

[0016] Further, a method for preparing the aforementioned chemical copper plating solution comprises the following steps: S1: Accurately weigh 16.00g of CuSO4·5H2O and dissolve it in 600mL of distilled water, stirring until the CuSO4·5H2O is completely dissolved; then, add 12.00mg of additive H and stir until the additive H is completely dissolved; transfer all the solution to a 1L volumetric flask, add pure water to the scale line, and prepare copper plating solution A; S2: Accurately weigh 12.00 g of sodium potassium tartrate and dissolve it in 600 mL of distilled water, stirring until the sodium potassium tartrate is completely dissolved; then, add 12.00 g of disodium ethylenediaminetetraacetate and stir until the disodium ethylenediaminetetraacetate is completely dissolved; when cooled to 30°C, add 22.00 mg of additive X and stir until the additive X is completely dissolved; transfer all the solution to a 1L volumetric flask, add pure water to the scale line, and prepare copper plating solution B; S3: Accurately weigh 12.00g of NaOH and dissolve it in 800mL of distilled water, stir until the NaOH is completely dissolved, and cool to below 40°C, then transfer all the solution to a 1L volumetric flask, add pure water to the scale line, and prepare copper plating solution C; S4: Copper plating solution D is 37% formaldehyde, which is added last in the chemical copper plating process.

[0017] In summary, the present invention discloses a chemical copper plating solution, which is composed of copper plating A solution, copper plating B solution, copper plating C solution and copper plating D solution mixed in a preset ratio. In addition, the present invention also discloses a method for preparing the aforementioned chemical copper plating solution, which is respectively prepared by adding 16 parts of CuSO4·5H2O and 0.012 parts of additive H to every 1000 parts of the solution by mass, and the balance is pure water or distilled water to prepare copper plating A solution; by adding 12 parts of potassium sodium tartrate, 12 parts of disodium ethylenediaminetetraacetate and 0.022 parts of additive X to every 1000 parts of the solution; the balance is pure water or distilled water to prepare copper plating B solution; by adding 12 parts of NaOH to every 1000 parts of the solution, and the balance is pure water or distilled water to prepare copper plating C solution; copper plating D solution uses 37% formaldehyde; the aforementioned chemical copper plating solution can be prepared by mixing the components. Formaldehyde is separated from the main plating solution and directly added as an independent reducing agent in the chemical copper plating process, which can reduce the harm to the human body caused by the strong irritating odor generated by formaldehyde during the stirring process when preparing the main plating solution A. In the present invention, the process of using formaldehyde to prepare the plating solution is eliminated by adjusting the ratio of each component of the plating solution, so as to realize the method of adding formaldehyde at the end of the chemical copper plating process. Therefore, the present invention can optimize the technical problems existing in the prior art such as low chemical copper plating deposition rate, poor plating solution stability and unqualified coating quality caused by eliminating the use of formaldehyde. DETAILED DESCRIPTION

[0018] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific implementation mode of the present invention is described in detail below in conjunction with specific embodiments. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0019] Specifically, the present invention provides a chemical copper plating solution, which is composed of a copper plating solution A, a copper plating solution B, a copper plating solution C and a copper plating solution D mixed in a preset ratio.

[0020] Specifically, in a technical solution of a chemical copper plating solution of the present invention, the proportions of the components are as follows, by mass: 10 parts of copper plating solution A, 12 to 15 parts of copper plating solution B, 10 to 15 parts of copper plating solution C, and 1.2 parts of copper plating solution D.

[0021] Specifically, in parts by mass, the copper plating solution A is prepared by adding 16 parts of CuSO4·5H2O and 0.012 parts of additive H to every 1000 parts of the solution; the remainder is pure water or distilled water.

[0022] Specifically, in parts by mass, the copper plating solution B is as follows: 12 parts of potassium sodium tartrate, 12 parts of disodium ethylenediaminetetraacetate and 0.022 parts of additive X are added to every 1000 parts of the solution; the remainder is pure water or distilled water.

[0023] Specifically, in parts by mass, the copper plating solution C is prepared by adding 12 parts of NaOH to every 1000 parts of the solution, and the remainder is pure water or distilled water.

[0024] Specifically, the aforementioned copper plating solution D is 37% formaldehyde.

[0025] Further, a method for preparing the aforementioned chemical copper plating solution comprises the following steps: S1: Accurately weigh 16.00g of CuSO4·5H2O and dissolve it in 600mL of distilled water, stirring until the CuSO4·5H2O is completely dissolved; then, add 12.00mg of additive H and stir until the additive H is completely dissolved; transfer all the solution to a 1L volumetric flask, add pure water to the scale line, and prepare copper plating solution A; S2: Accurately weigh 12.00 g of sodium potassium tartrate and dissolve it in 600 mL of distilled water, stirring until the sodium potassium tartrate is completely dissolved; then, add 12.00 g of disodium ethylenediaminetetraacetate and stir until the disodium ethylenediaminetetraacetate is completely dissolved; when cooled to 30°C, add 22.00 mg of additive X and stir until the additive X is completely dissolved; transfer all the solution to a 1L volumetric flask, add pure water to the scale line, and prepare copper plating solution B; S3: Accurately weigh 12.00g of NaOH and dissolve it in 800mL of distilled water, stir until the NaOH is completely dissolved, and cool to below 40°C, then transfer all the solution to a 1L volumetric flask, add pure water to the scale line, and prepare copper plating solution C; S4: Copper plating solution D is 37% formaldehyde, which is added last in the chemical copper plating process.

[0026] Furthermore, the aforementioned additive H may be a surfactant, for example, it may be at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polyethylene glycol, polyethyleneimine or sodium dodecyl alcohol polyoxyethylene ether sulfate.

[0027] Specifically, the aforementioned surfactant can improve the compactness of the copper plating layer: the surfactant can reduce the surface tension of the plating solution, making it easier for the plating solution to be evenly distributed on the surface of the workpiece, thereby forming a more uniform and dense plating layer. Reduce hydrogen embrittlement: the surfactant can improve the interface state between the plating layer and the base metal, reduce the diffusion and accumulation of hydrogen atoms in the plating layer, thereby reducing the risk of hydrogen embrittlement. Improve the performance of the plating solution: the surfactant can enhance the wettability and fluidity of the plating solution, making it easier for the plating solution to spread on the surface of the workpiece, thereby improving the efficiency of electroplating.

[0028] For example, sodium dodecyl sulfate is an anionic surfactant with good wettability and foaming properties. Sodium dodecylbenzene sulfonate is another anionic surfactant with excellent dispersibility and stability. Polyethylene glycol is a nonionic surfactant with good lubricity and antistatic properties. Polyethyleneimine is a cationic surfactant that can improve the adhesion and corrosion resistance of the coating. Sodium dodecyl alcohol polyoxyethylene ether sulfate has excellent dispersibility and wetting properties, which helps to evenly distribute the plating solution on the surface of the workpiece.

[0029] Furthermore, the aforementioned additive X may be a stabilizer, for example, it may be at least one of polyvinyl pyrrolidone, organic sulfur compounds, potassium ferrocyanide, bipyridine, thioglycolic acid, phenylcyclotetrazolyl, N-phenylnaphthalenesulfonamide or sodium propylene oxide sulfonate.

[0030] Specifically, the aforementioned stabilizer can control the reduction rate: the stabilizer can control the reduction rate of copper ions to prevent the roughness of the coating or even peeling of the coating due to too fast reduction. Or prevent premature deposition: without the participation of stabilizers, the chemical copper plating reaction may get out of control, resulting in the so-called "premature deposition", that is, the copper ions spontaneously and disorderly reduce and deposit in the solution, resulting in not only rough and uneven coating, but also possible pipe blockage and system failure during the storage and operation of the chemical copper plating solution. In addition, the quality of the coating can also be improved: the stabilizer can ensure that the coating obtains stable electrochemical properties over a wide range of pH and temperature, prevent uneven copper deposition and the generation of impurity ions, thereby improving the quality of the coating. For example, polyvinyl pyrrolidone, or PVP, can form a stable complex with copper ions, thereby inhibiting the deposition of copper ions in unintended areas. Organic sulfur compounds, which are certain sulfur-containing organic compounds, can also form complexes with copper ions, stabilizing the plating solution. Potassium ferrocyanide can form a stable complex with cuprous ions, preventing their disproportionation reaction to copper, providing plating solution stability. Bipyridine can also form a stable complex with cuprous ions, stabilizing the plating solution. Thioglycolic acid mainly maintains the concentration of copper ions in the plating solution by forming a stable complex with copper ions; it is suitable for a wide pH and temperature range, and has a high tolerance for impurity ions. Benzene ring tetrazole can consume and prevent the generation of impurity ions, and can ensure the concentration of copper ions in the copper plating solution under stable conditions. N-phenylnaphthalenesulfonamide, its function is to passivate the surface and prevent the precipitation of copper salts; at the same time, it can also effectively prevent copper from being deposited on the non-copper part of the metal medium. Sodium propylene oxide sulfonate can increase the ionic strength of the plating solution, making the copper deposition more uniform and improving the copper plating quality.

[0031] Further, in a specific embodiment, the specific method of applying the chemical copper plating solution disclosed in the present invention is as follows: by weight, the chemical copper plating solution is 10% copper plating A solution, 15% copper plating B solution, 10% copper plating C solution and 1.2% copper plating D solution; the chemical copper plating temperature is 43°C and the time is 15min; First, prepare the solutions required for copper wire bulking, degumming, neutralization, degreasing, micro-etching, pre-impregnation, activation, and copper deposition in sequence, and heat them to the required temperature; then put the double-sided board through the copper deposition process in sequence, during which the copper deposition board needs to be swung back and forth to make it fully contact with the solution: soak in the bulking tank for 7 minutes and rinse twice; soak in the degumming tank for 12-15 minutes, and soak in the neutralization solution for 5 minutes; soak in the degreasing tank for 7 minutes and rinse twice; soak in the micro-etching tank for 1.5 minutes and rinse twice; soak in the pre-impregnation tank for 1.5 minutes, no need to rinse; soak in the activation tank for 7 minutes and rinse twice; soak in the acceleration tank for 3 minutes and rinse twice; put it in the copper deposition tank, sink copper for 15 minutes, and add the required solution in time; finally, observe the backlight level.

[0032] Further, in another specific embodiment, the specific method of applying the chemical copper plating solution disclosed in the present invention is as follows: by weight, the chemical copper plating solution is 10% copper plating A solution, 12% copper plating B solution, 12% copper plating C solution and 1.2% copper plating D solution; the chemical copper plating temperature is 45°C and the time is 15min; First, prepare the solutions required for copper wire bulking, degumming, neutralization, degreasing, micro-etching, pre-impregnation, activation, and copper deposition in sequence, and heat them to the required temperature; then put the double-sided board through the copper deposition process in sequence, during which the copper deposition board needs to be swung back and forth to make it fully contact with the solution: soak in the bulking tank for 7 minutes and rinse twice; soak in the degumming tank for 12-15 minutes, and soak in the neutralization solution for 5 minutes; soak in the degreasing tank for 7 minutes and rinse twice; soak in the micro-etching tank for 1.5 minutes and rinse twice; soak in the pre-impregnation tank for 1.5 minutes, no need to rinse; soak in the activation tank for 7 minutes and rinse twice; soak in the acceleration tank for 3 minutes and rinse twice; put it in the copper deposition tank, sink copper for 15 minutes, and add the required solution in time; finally, observe the backlight level.

[0033] In summary, the present invention discloses a chemical copper plating solution, which is composed of copper plating A solution, copper plating B solution, copper plating C solution and copper plating D solution mixed in a preset ratio. In addition, the present invention also discloses a method for preparing the aforementioned chemical copper plating solution, which is respectively prepared by adding 16 parts of CuSO4·5H2O and 0.012 parts of additive H to every 1000 parts of the solution by mass, and the balance is pure water or distilled water to prepare copper plating A solution; by adding 12 parts of potassium sodium tartrate, 12 parts of disodium ethylenediaminetetraacetate and 0.022 parts of additive X to every 1000 parts of the solution; the balance is pure water or distilled water to prepare copper plating B solution; by adding 12 parts of NaOH to every 1000 parts of the solution, and the balance is pure water or distilled water to prepare copper plating C solution; copper plating D solution uses 37% formaldehyde; the aforementioned chemical copper plating solution can be prepared by mixing the components. Formaldehyde is separated from the main plating solution and directly added as an independent reducing agent in the chemical copper plating process, which can reduce the harm to the human body caused by the strong irritating odor generated by formaldehyde during the stirring process when preparing the main plating solution A. In the present invention, the process of using formaldehyde to prepare the plating solution is eliminated by adjusting the ratio of each component of the plating solution, so as to realize the method of adding formaldehyde at the end of the chemical copper plating process. Therefore, the present invention can optimize the technical problems of low chemical copper plating deposition rate, poor plating solution stability and unqualified coating quality caused by the elimination of formaldehyde in the prior art.

[0034] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0035] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A chemical copper plating solution, characterized in that: The method is composed of copper plating liquid A, copper plating liquid B, copper plating liquid C and copper plating liquid D mixed in a preset ratio.

2. A chemical copper plating solution according to claim 1, characterized in that: In parts by mass, the copper plating solution A is: 16 parts of CuSO4·5H2O and 0.012 parts of additive H are added to every 1000 parts of the solution; the remainder is pure water or distilled water.

3. A chemical copper plating solution according to claim 2, characterized in that: In parts by mass, the copper plating solution B is: 12 parts of potassium sodium tartrate, 12 parts of disodium ethylenediaminetetraacetate and 0.022 parts of additive X are added to every 1000 parts of the solution; the remainder is pure water or distilled water.

4. A chemical copper plating solution according to claim 3, characterized in that: Calculated by mass, the copper plating C solution is: 12 parts of NaOH are added to every 1000 parts of the solution, and the remainder is pure water or distilled water.

5. A chemical copper plating solution according to claim 4, characterized in that: Copper plating solution D is 37% formaldehyde.

6. A chemical copper plating solution according to claim 5, characterized in that: The proportions of the components are as follows by mass: 10 parts of copper plating A solution, 12 to 15 parts of copper plating B solution, 10 to 15 parts of copper plating C solution and 1.2 parts of copper plating D solution.

7. A chemical copper plating solution according to claim 1, characterized in that: The additive H is at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, polyethylene glycol, polyethyleneimine or sodium dodecyl alcohol polyoxyethylene ether sulfate.

8. A chemical copper plating solution according to claim 1, characterized in that: The additive X is at least one of polyvinyl pyrrolidone, organic sulfur compounds, potassium ferrocyanide, bipyridine, thioglycolic acid, phenyltetrazolyl, N-phenylnaphthalenesulfonamide or sodium propylene oxide sulfonate.

9. A method for preparing a chemical copper plating solution as claimed in claim 5, characterized in that: It includes the following steps: S1: Accurately weigh 16.00g of CuSO4·5H2O and dissolve it in 600mL of distilled water, stirring until the CuSO4·5H2O is completely dissolved; then, add 12.00mg of additive H and stir until the additive H is completely dissolved; transfer all the solution to a 1L volumetric flask, add pure water to the scale line, and prepare copper plating solution A; S2: Accurately weigh 12.00 g of sodium potassium tartrate and dissolve it in 600 mL of distilled water, stirring until the sodium potassium tartrate is completely dissolved; then, add 12.00 g of disodium ethylenediaminetetraacetate and stir until the disodium ethylenediaminetetraacetate is completely dissolved; when cooled to 30°C, add 22.00 mg of additive X and stir until the additive X is completely dissolved; transfer all the solution to a 1L volumetric flask, add pure water to the scale line, and prepare copper plating solution B; S3: Accurately weigh 12.00g of NaOH and dissolve it in 800mL of distilled water, stir until the NaOH is completely dissolved, and cool to below 40°C, then transfer all the solution to a 1L volumetric flask, add pure water to the scale line, and prepare copper plating solution C; S4: Copper plating solution D is 37% formaldehyde, which is added last in the chemical copper plating process.