Chemical copper plating solution beneficial to improving surface roughness, production process and application

Abstract

The invention discloses a chemical copper plating solution helpful for improving surface roughness, a production process and application, and belongs to the technical field of chemical copper plating solutions, and per liter of the chemical copper plating solution comprises the following raw materials: 16.1-21.8 g of copper salt; 3.6 to 5.2 g of a reducing agent; 10.3 g to 12.5 g of a complexing agent; 9.3 to 23.5 g of a pH (Potential of Hydrogen) regulator; 3.8 to 6.2 g of an inhibitor; 0.08 to 0.21 g of a surface modification auxiliary agent; and the balance of deionized water. The inhibitor is prepared from the following raw materials in percentage by weight: 25.7 to 35.2 percent of a silane coupling agent, 16.9 to 22.3 percent of polyacrylate, 16.2 to 18.6 percent of sucrose and the balance of deionized water, the surface modification auxiliary agent adopts polyethylene glycol modified sodium alginate nanogel; the inhibitor is weak in affinity to copper ions, unstable intermediate products or precipitates generated in the reaction are prevented from influencing the stability of the plating solution, the prepared plating solution is free of obvious turbidity and impurities, the flatness of a copper plating layer is good, and the surface roughness is effectively reduced.

Description

Technical Field

[0001] The invention relates to the technical field of chemical copper plating solution, and in particular to a chemical copper plating solution, a production process and an application thereof which are helpful in improving surface roughness. Background Art

[0002] Chemical copper plating technology is a technology that uses chemical reducing agents to reduce copper ions in the solution into metallic copper and deposit it on the surface of the plated part without an external current. It is commonly used in the fields of printed circuit board (PCB) manufacturing and plastic electroplating.

[0003] The ingredients of chemical copper plating solution generally contain copper salts, reducing agents, chelating agents and pH adjusters. Common copper salts include copper sulfate, copper chloride, copper nitrate, etc., reducing agents include formaldehyde, etc., chelating agents include EDTA, disodium EDTA, etc., and pH adjusters include sodium hydroxide, etc.

[0004] At present, in order to improve the surface roughness of products, the method of adding brighteners, leveling agents, and inhibitors (such as benzotriazole (BTA) etc.) is generally adopted. Among them, the inhibitor principle is: the inhibitor molecules can selectively adsorb on the active sites on the surface of the plated part or the growth points of the copper crystals, preventing new copper atoms from continuing to deposit at the positions where the inhibitors have been adsorbed. Copper atoms can only be deposited in areas not covered by the inhibitors, thereby changing the growth mode of the copper crystals, slowing down the growth rate, and making the growth of the crystals more orderly, which is conducive to the formation of a delicate and uniform copper plating layer. At the same time, the inhibitor reacts with copper salts to form a protective film on the surface of the copper plating layer, further limiting the disordered growth of copper crystals, which is conducive to improving the surface roughness of the copper plating layer.

[0005] However, the inhibitor may have complex interactions with other components in the plating solution. For example, if the inhibitor is a nitrogen-containing heterocyclic compound, it may compete with the complexing agent for coordination with the copper ions. If the inhibitor has a strong affinity for copper ions, it will seize copper ions from the complexing agent-copper ion complex to form an inhibitor-copper ion complex. On the one hand, this reaction may produce unstable intermediates or precipitates, affecting the stability of the plating solution and causing the plating solution to become turbid. If it is mixed in the copper plating layer, it will affect the quality of the copper plating layer. On the other hand, the new complex or precipitate generated adheres to the surface of the plated part, which will reduce the flatness of the copper plating layer and increase the surface roughness.

[0006] Based on this, the present invention designs a chemical copper plating solution, a production process and an application that are helpful to improve the surface roughness to solve the above problems. Summary of the invention

[0007] In view of the above-mentioned shortcomings of the prior art, the present invention provides a chemical copper plating solution, a production process and an application thereof which are helpful in improving surface roughness.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: Chemical copper plating solution that helps improve surface roughness. Each liter of chemical copper plating solution includes the following raw materials: Copper salt: 16.1-21.8 g; Reducing agent: 3.6-5.2 g; Complexing agent: 10.3-12.5 g; pH adjuster: 9.3-23.5 g; Inhibitor: 3.8-6.2 g; Surface modification auxiliary agent: 0.08-0.21 g; The balance is deionized water; The inhibitor comprises the following raw materials in weight percentage: 25.7-35.2% silane coupling agent, 16.9-22.3% polyacrylate, 16.2-18.6% sucrose, and the balance is deionized water; The surface modification auxiliary agent is polyethylene glycol-modified sodium alginate nanogel; the polyethylene glycol-modified sodium alginate nanogel is obtained by freeze-drying and crushing the sodium alginate nanogel and then adding the resulting solution to polyethylene glycol with a concentration of 15.3-18.6w% for swelling reaction for 15-20 minutes.

[0009] Furthermore, the silane coupling agent is γ-glycidyloxypropyltrimethoxysilane.

[0010] Furthermore, the polyacrylate is sodium polyacrylate.

[0011] Furthermore, the preparation method of the inhibitor is: Step (1), at room temperature, sucrose is added to deionized water to form a sucrose solution; Step (2), heating to 48-60° C., stirring at 300-350 rpm, slowly adding 1 / 2 of the silane coupling agent to the sucrose solution, and the silane coupling agent is evenly dispersed and hydrolyzed for 30-35 minutes to provide active sites for the reaction; Step (3), at 45-55° C., mix the remaining 1 / 2 of the silane coupling agent with the polyacrylate, and stir at 150-200 rpm for 40-55 minutes to ensure that the reaction is fully carried out; Step (4), adjusting the pH value of the solution obtained in step (2) to 10-11, and adding the product obtained in step (3) dropwise to the solution obtained in step (2), with the dropping speed controlled at 1.5-3.0 g / min and the stirring speed at 300-500 rpm.

[0012] Furthermore, the complexing agent is a mixture of sodium tripolyphosphate, nitrilotriacetic acid and sodium tartrate in a ratio of 2-2.2:3.1-3.7:0.5-1.

[0013] Furthermore, the copper salt is selected from a combination of one or more of copper sulfate, copper chloride and copper nitrate.

[0014] Furthermore, the reducing agent is sodium hypophosphite.

[0015] Furthermore, the pH regulator is sodium hydroxide.

[0016] In order to better achieve the purpose of the present invention, the present invention also provides a production process of the chemical copper plating solution that helps to improve surface roughness, comprising the following steps: Step a, at room temperature, stirring and mixing the inhibitor and the surface modification auxiliary agent to obtain a mixture A for standby use; Step b, taking a container and adding deionized water, then slowly adding copper salt into the deionized water, stirring while adding, and controlling the stirring speed at 100-150 rpm to obtain a solution with uniformly distributed copper ions; Step c, adding a complexing agent to a solution container in which copper ions are evenly distributed, also slowly adding and stirring, the stirring speed is controlled at 150-185 rpm, so that the complexing agent and the copper ions are fully complexed, and then adjusting the pH value of the solution to 11-13 with a pH adjusting agent to obtain a mixture B; Step d: then add a reducing agent to the mixture B and stir for 10-15 minutes; then add the mixture A, control the stirring speed at 200-255 rpm, and stir for 15-20 minutes to obtain a chemical copper plating solution that helps improve the surface roughness.

[0017] In order to better achieve the purpose of the present invention, the present invention also provides the application of the chemical copper plating solution in the fields of printed circuit board manufacturing and plastic electroplating.

[0018] Compared with the prior art, the present invention has the following beneficial effects: the inhibitor of the present invention has a weak affinity for copper ions, which avoids the reaction to produce unstable intermediate products or precipitation that affect the stability of the plating solution. The prepared plating solution has no obvious turbidity and impurities, the copper plating layer has good flatness, and the surface roughness is effectively reduced. When preparing the inhibitor, first prepare a sucrose solution; then add 1 / 2 of the silane coupling agent to the sucrose solution for uniform dispersion and hydrolysis to provide active sites for the reaction, and adjust the pH value of the resulting solution to 10-11. Using 1 / 2 of the silane coupling agent can avoid the hydrolysis reaction being too intense, the active sites being generated too quickly and unevenly distributed, which is not conducive to subsequent orderly reactions. Afterwards, the remaining 1 / 2 of the silane coupling agent is mixed with the polyacrylate to react to form a relatively stable intermediate product, which is conducive to more orderly further reactions; finally, the two solutions are mixed, which is conducive to avoiding excessively intense reactions caused by mixing all reactants at one time, which affects the inhibitor effect. The surface modification auxiliary agent adopts polyethylene glycol to modify the sodium alginate nanogel, so that the polyethylene glycol molecules can penetrate into the gel and interact with the sodium alginate molecular chains, thereby achieving effective modification of the sodium alginate nanogel, reducing the surface energy, being able to better adsorb on the surface of the workpiece to be plated, enhancing the network structure stability of the gel, being conducive to reducing the surface roughness, enhancing the bonding force between the coating and the workpiece to be plated, and enhancing the bending resistance. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Embodiment 1: A production process of a chemical copper plating solution that helps improve surface roughness comprises the following steps: Step 1, weigh the raw materials: each 1 liter of chemical copper plating solution includes the following raw materials: copper salt: 16.1 g, copper sulfate; reducing agent: 5.2 g, sodium hypophosphite; complexing agent: 10.3 g, sodium tripolyphosphate, nitrilotriacetic acid and sodium tartrate mixed according to 2.2:3.1:1; pH adjuster: 9.3 g, sodium hydroxide; inhibitor: 6.2 g; surface modification auxiliary agent: 0.08 g; the balance is deionized water.

[0021] The inhibitor comprises the following raw materials in weight percentage: 25.7% silane coupling agent, 22.3% polyacrylate, 16.2% sucrose, and the balance is deionized water; the silane coupling agent is γ-glycidyloxypropyltrimethoxysilane; the polyacrylate is sodium polyacrylate. The preparation method of the inhibitor comprises the following steps: step (1), at room temperature, adding sucrose to deionized water to form a sucrose solution; step (2), heating to 48° C., controlling the stirring speed at 350 rpm, slowly adding 1 / 2 of a silane coupling agent to the sucrose solution, uniformly dispersing the silane coupling agent and hydrolyzing it for 30 minutes to provide active sites for the reaction; step (3), at 55° C., mixing the remaining 1 / 2 of the silane coupling agent with polyacrylate, stirring at 150 rpm for 55 minutes to ensure that the reaction is fully carried out; step (4), adjusting the pH value of the solution obtained in step (2) to 10-11, and dripping the product obtained in step (3) into the solution obtained in step (2), controlling the dripping speed at 1.5 g / min, and stirring at 500 rpm.

[0022] The surface modification auxiliary agent is polyethylene glycol-modified sodium alginate nanogel; the sodium alginate nanogel is freeze-dried, crushed, and then added to a 15.3w% polyethylene glycol aqueous solution for swelling reaction for 20 minutes to obtain the polyethylene glycol-modified sodium alginate nanogel.

[0023] Step 2: at room temperature, the inhibitor and the surface modification auxiliary agent are stirred and mixed uniformly to obtain a mixture A for standby use; Step 3, take a container and add deionized water, then slowly add copper salt into the deionized water, stirring while adding, and controlling the stirring speed at 100 rpm to obtain a solution with uniformly distributed copper ions; Step 4, adding a complexing agent to a solution container in which copper ions are evenly distributed, and also slowly adding and stirring, the stirring speed is controlled at 150 rpm, so that the complexing agent and the copper ions are fully complexed, and then the pH value of the solution is adjusted to 11-13 by a pH adjusting agent to obtain a mixture B; Step 5: Then, a reducing agent is added to the mixture B and stirred for 10 minutes; then, the mixture A is added and the stirring speed is controlled at 255 rpm and stirred for 15 minutes to obtain a chemical copper plating solution that helps to improve the surface roughness.

[0024] Embodiment 2: A production process of a chemical copper plating solution that helps improve surface roughness comprises the following steps: Step 1, weigh the raw materials: each 1 liter of chemical copper plating solution includes the following raw materials: copper salt: 21.8 g, a composition of copper chloride and copper nitrate in a mass ratio of 1:1; reducing agent: 3.6 g, sodium hypophosphite; complexing agent: 12.5 g, sodium tripolyphosphate, nitrilotriacetic acid and sodium tartrate mixed in a ratio of 2:3.7:0.5; pH regulator: 23.5 g, sodium hydroxide; inhibitor: 3.8 g; surface modification auxiliary agent: 0.21 g; the balance is deionized water.

[0025] The inhibitor comprises the following raw materials in weight percentage: 35.2% of silane coupling agent, 16.9% of polyacrylate, 18.6% of sucrose, and the balance of deionized water; the silane coupling agent is γ-glycidyloxypropyltrimethoxysilane; the polyacrylate is sodium polyacrylate. The preparation method of the inhibitor comprises the following steps: step (1), at room temperature, sucrose is added to deionized water to form a sucrose solution; step (2), the temperature is raised to 60° C., the stirring speed is controlled at 300 rpm, 1 / 2 of the silane coupling agent is slowly added to the sucrose solution, the silane coupling agent is uniformly dispersed and hydrolyzed for 35 minutes, and active sites are provided for the reaction; step (3), at 45° C., the remaining 1 / 2 of the silane coupling agent is mixed with polyacrylate, and the mixture is stirred at 200 rpm for 40 minutes to ensure that the reaction is fully carried out; step (4), the pH value of the solution obtained in step (2) is adjusted to 10-11, the product obtained in step (3) is dripped into the solution obtained in step (2), the dripping speed is controlled at 3.0 g / min, and the stirring speed is 300 rpm.

[0026] The surface modification auxiliary agent is polyethylene glycol-modified sodium alginate nanogel; the sodium alginate nanogel is freeze-dried, crushed, and then added to an aqueous solution of polyethylene glycol with a concentration of 18.6w% for swelling reaction for 15 minutes to obtain the polyethylene glycol-modified sodium alginate nanogel.

[0027] Step 2: at room temperature, the inhibitor and the surface modification auxiliary agent are stirred and mixed uniformly to obtain a mixture A for standby use; Step 3, take a container and add deionized water, then slowly add copper salt into the deionized water, stirring while adding, and controlling the stirring speed at 150 rpm to obtain a solution with uniformly distributed copper ions; Step 4, adding a complexing agent to a solution container in which copper ions are evenly distributed, and also slowly adding and stirring, the stirring speed is controlled at 150 rpm, so that the complexing agent and the copper ions are fully complexed, and then the pH value of the solution is adjusted to 11-13 by a pH adjusting agent to obtain a mixture B; Step 5: Then, add a reducing agent to the mixture B and stir for 15 minutes; then add the mixture A, control the stirring speed at 200 rpm, and stir for 20 minutes to obtain a chemical copper plating solution that helps improve the surface roughness.

[0028] Embodiment 3: A production process of a chemical copper plating solution that helps improve surface roughness comprises the following steps: Step 1, weigh the raw materials: each 1 liter of chemical copper plating solution includes the following raw materials: copper salt: 18.5 g, copper chloride; reducing agent: 4.6 g, sodium hypophosphite; complexing agent: 11.4 g, sodium tripolyphosphate, nitrilotriacetic acid and sodium tartrate mixed according to 2.1:3.5:0.7; pH regulator: 15.5 g, sodium hydroxide; inhibitor: 5.3 g; surface modification auxiliary agent: 0.12 g; the balance is deionized water.

[0029] The inhibitor comprises the following raw materials in weight percentage: 28.9% silane coupling agent, 18.6% polyacrylate, 17.1% sucrose, and the balance is deionized water; the silane coupling agent is γ-glycidyloxypropyltrimethoxysilane; the polyacrylate is sodium polyacrylate. The preparation method of the inhibitor comprises the following steps: step (1), at room temperature, adding sucrose to deionized water to form a sucrose solution; step (2), heating to 55° C., controlling the stirring speed at 320 rpm, slowly adding 1 / 2 of a silane coupling agent to the sucrose solution, uniformly dispersing the silane coupling agent and hydrolyzing it for 32 minutes to provide active sites for the reaction; step (3), at 48° C., mixing the remaining 1 / 2 of the silane coupling agent with polyacrylate, stirring at 180 rpm for 45 minutes to ensure that the reaction is fully carried out; step (4), adjusting the pH value of the solution obtained in step (2) to 10-11, and dripping the product obtained in step (3) into the solution obtained in step (2), controlling the dripping speed at 2 g / min, and stirring at 400 rpm.

[0030] The surface modification auxiliary agent is polyethylene glycol-modified sodium alginate nanogel; the sodium alginate nanogel is freeze-dried, crushed, and then added to a 16.8w% polyethylene glycol aqueous solution for swelling reaction for 18 minutes to obtain the polyethylene glycol-modified sodium alginate nanogel.

[0031] Step 2: at room temperature, the inhibitor and the surface modification auxiliary agent are stirred and mixed uniformly to obtain a mixture A for standby use; Step 3, take a container and add deionized water, then slowly add copper salt into the deionized water, stirring while adding, and controlling the stirring speed at 130 rpm to obtain a solution with uniformly distributed copper ions; Step 4, adding a complexing agent to a solution container in which copper ions are evenly distributed, and also slowly adding and stirring, with the stirring speed controlled at 170 rpm, so that the complexing agent and the copper ions are fully complexed, and then adjusting the pH value of the solution to 11-13 with a pH adjusting agent to obtain a mixture B; Step 5: Then, a reducing agent is added to the mixture B and stirred for 12 minutes; then, the mixture A is added and the stirring speed is controlled at 250 rpm and stirred for 17 minutes to obtain a chemical copper plating solution that helps to improve the surface roughness.

[0032] Comparative Example 1: The difference from Example 3 is that the preparation method of the inhibitor is replaced by: directly blending the silane coupling agent, polyacrylate, sucrose and deionized water.

[0033] Comparative Example 2: The difference from Example 3 is that the surface modification auxiliary agent is replaced by sodium alginate nanogel.

[0034] Comparative Example 3: The difference from Example 3 is that the inhibitor is replaced by benzotriazole.

[0035] Experimental Example: The workpiece to be plated (ABS plastic) was placed in the chemical copper plating solution of Examples 1-3 and Comparative Examples 1-3 at 75°C for 1 hour to obtain plated parts. The performance of each plated part was tested. The results are shown in Table 1.

[0036] Surface roughness: GB / T 3505-2009.

[0037] Test the adhesion between the coating and the workpiece to be plated: coating adhesion scratch tester.

[0038] Bending test: repeatedly bend the plated part 120 degrees until cracks appear on the copper plating layer and the number of bends is recorded.

[0039] Table 1 Performance test results

[0040] The inhibitor of the present invention has a weak affinity for copper ions, which avoids the reaction to produce unstable intermediate products or precipitation that affect the stability of the plating solution. The prepared plating solution has no obvious turbidity and impurities, the copper plating layer has good flatness, and the surface roughness is effectively reduced. When preparing the inhibitor, first prepare a sucrose solution; then add 1 / 2 of the silane coupling agent to the sucrose solution for uniform dispersion and hydrolysis to provide active sites for the reaction, and adjust the pH value of the resulting solution to 10-11. Using 1 / 2 of the silane coupling agent can avoid the hydrolysis reaction being too intense, the active sites being generated too quickly and unevenly distributed, which is not conducive to subsequent orderly reactions. Afterwards, the remaining 1 / 2 of the silane coupling agent is mixed with polyacrylate to react to form a relatively stable intermediate product, which is conducive to more orderly further reactions; finally, the two solutions are mixed, which is conducive to avoiding excessively intense reactions caused by mixing all reactants at one time, which affects the inhibitor effect. The surface modification auxiliary agent adopts polyethylene glycol to modify the sodium alginate nanogel, so that the polyethylene glycol molecules can penetrate into the gel and interact with the sodium alginate molecular chains, thereby achieving effective modification of the sodium alginate nanogel, reducing the surface energy, being able to better adsorb on the surface of the workpiece to be plated, enhancing the network structure stability of the gel, being conducive to reducing the surface roughness, enhancing the bonding force between the coating and the workpiece to be plated, and enhancing the bending resistance.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A chemical copper plating solution that helps improve surface roughness, characterized in that: Each 1 liter of chemical copper plating solution includes the following raw materials: Copper salt: 16.1-21.8 g; Reducing agent: 3.6-5.2 g; Complexing agent: 10.3-12.5 g; pH adjuster: 9.3-23.5 g; Inhibitor: 3.8-6.2 g; Surface modification auxiliary agent: 0.08-0.21 g; The balance is deionized water; The inhibitor comprises the following raw materials in weight percentage: 25.7-35.2% silane coupling agent, 16.9-22.3% polyacrylate, 16.2-18.6% sucrose, and the balance is deionized water; The surface modification auxiliary agent is polyethylene glycol-modified sodium alginate nanogel; the polyethylene glycol-modified sodium alginate nanogel is obtained by freeze-drying and crushing the sodium alginate nanogel and then adding the resulting solution to polyethylene glycol with a concentration of 15.3-18.6w% for swelling reaction for 15-20 minutes.

2. The chemical copper plating solution for improving surface roughness according to claim 1, characterized in that: The silane coupling agent is γ-glycidyloxypropyltrimethoxysilane.

3. The chemical copper plating solution for improving surface roughness according to claim 2, characterized in that: The polyacrylate is sodium polyacrylate.

4. The chemical copper plating solution for improving surface roughness according to claim 3, characterized in that: The preparation method of the inhibitor is: Step (1), at room temperature, sucrose is added to deionized water to form a sucrose solution; Step (2), heating to 48-60° C., stirring at 300-350 rpm, slowly adding 1 / 2 of the silane coupling agent to the sucrose solution, and the silane coupling agent is evenly dispersed and hydrolyzed for 30-35 minutes to provide active sites for the reaction; Step (3), at 45-55° C., mix the remaining 1 / 2 of the silane coupling agent with the polyacrylate, and stir at 150-200 rpm for 40-55 minutes to ensure that the reaction is fully carried out; Step (4), adjusting the pH value of the solution obtained in step (2) to 10-11, and adding the product obtained in step (3) dropwise to the solution obtained in step (2), with the dropping speed controlled at 1.5-3.0 g / min and the stirring speed at 300-500 rpm.

5. The chemical copper plating solution for improving surface roughness according to claim 4, characterized in that: The complexing agent is a mixture of sodium tripolyphosphate, nitrilotriacetic acid and sodium tartrate in a ratio of 2-2.2:3.1-3.7:0.5-1.

6. The chemical copper plating solution for improving surface roughness according to claim 5, characterized in that: The copper salt is selected from a combination of one or more of copper sulfate, copper chloride and copper nitrate.

7. The chemical copper plating solution for improving surface roughness according to claim 6, characterized in that: The reducing agent is sodium hypophosphite.

8. The chemical copper plating solution for improving surface roughness according to claim 7, characterized in that: The pH regulator is sodium hydroxide.

9. A production process of a chemical copper plating solution that helps improve surface roughness according to claim 8, characterized in that: The following steps are involved: Step a, at room temperature, stirring and mixing the inhibitor and the surface modification auxiliary agent to obtain a mixture A for standby use; Step b, taking a container and adding deionized water, then slowly adding copper salt into the deionized water, stirring while adding, and controlling the stirring speed at 100-150 rpm to obtain a solution with uniformly distributed copper ions; Step c, adding a complexing agent to a solution container in which copper ions are evenly distributed, also slowly adding and stirring, the stirring speed is controlled at 150-185 rpm, so that the complexing agent and the copper ions are fully complexed, and then adjusting the pH value of the solution to 11-13 with a pH adjusting agent to obtain a mixture B; Step d: then add a reducing agent to the mixture B and stir for 10-15 minutes; then add the mixture A, control the stirring speed at 200-255 rpm, and stir for 15-20 minutes to obtain a chemical copper plating solution that helps improve the surface roughness.

10. Use of the chemical copper plating solution according to any one of claims 1 to 8 in the fields of printed circuit board manufacturing and plastic electroplating.

Images