Copper alloy surface micro-etching liquid and preparation method thereof

Abstract

The invention relates to a copper alloy surface micro-etching solution and a preparation method thereof, and belongs to the technical field of micro-etching solutions. The copper alloy surface micro-etching liquid is prepared by taking a self-made supported phosphotungstic heteropolyacid catalyst, glacial acetic acid, a hydrogen peroxide solution, a buffer agent, a stabilizer and a corrosion inhibitor as raw materials, and the copper alloy surface micro-etching liquid is prepared by the following steps: firstly, synthesizing peracetic acid with higher oxidability by using the catalyst, hydrogen peroxide and glacial acetic acid; according to the micro-etching liquid, the copper alloy surface is etched under the weak acidic condition, the conductivity of the micro-etching liquid is further reduced, the purpose of inhibiting the galvanic effect of the copper alloy surface is achieved, in addition, due to the existence of a large number of acetate ions, the content of metal ions in the micro-etching liquid is very low, a pH buffer system exists, and the corrosion resistance of the copper alloy surface is improved. The influence of the overall oxidability of the micro-etching liquid along with the change of the reaction time is small, the etching effect is uniform, the concentration of a single component can be reduced through a hydrogen peroxide / peracetic acid compound system, and damage to a base material due to the too high single component is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of microetching solutions, and specifically relates to a microetching solution for copper alloy surfaces and a preparation method thereof. Background Art

[0002] Chemical microetching is a common process for the pretreatment of copper alloys. Its basic principle is to utilize an oxidant to undergo an oxidation-reduction reaction with the surface of the copper alloy under acidic conditions, while strong acids dissolve the oxides generated on the surface of the copper alloy, thereby achieving the effects of cleaning and roughening the surface of the copper alloy to improve the mechanical bite force between the copper alloy and the surface coating. In the commonly used microetching systems in the prior art, the nitrate system has too strong a corrosive effect on equipment, and the nitrogen oxide waste gas generated by the reaction also needs to be treated additionally, resulting in a relatively high equipment investment. The sodium sulfate generated by the persulfate system needs to be separated by crystallization, and the copper ion-containing wastewater generated also needs to be treated additionally. The hydrogen peroxide-sulfuric acid system has a large copper dissolution capacity and is environmentally friendly, but the decomposition rate of hydrogen peroxide is affected by metal ions. As the reaction progresses and the concentration of copper ions increases, the change in the etching rate will lead to uneven etching effects.

[0003] Chemical microetching can improve the bonding ability of copper alloys, but the slits generated after roughening will also cause microetching solution residues, and these residual microetching solutions are difficult to completely remove even after water washing or ultrasonic treatment. These residual acidic microetching solutions can form an electrochemical circuit with the copper alloy and the coating metal on the surface of the copper alloy, exacerbating the corrosion of copper, that is, the galvanic effect. Based on this, the present invention provides a microetching solution for copper alloy surfaces and a preparation method thereof. Summary of the Invention

[0004] The purpose of the present invention is to provide a microetching solution for copper alloy surfaces and a preparation method thereof to solve the problems mentioned in the above background art.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A microetching solution for copper alloy surfaces, comprising the following components: 1.6 - 4.8 g / L of a catalyst, 15 - 27 g / L of glacial acetic acid, 28 - 46 g / L of a hydrogen peroxide solution, 6 - 10 g / L of a buffer, 1 - 4 g / L of a stabilizer, 1 - 10 g / L of a corrosion inhibitor, and the balance being deionized water; A preparation method of a microetching solution for copper alloy surfaces, comprising the following steps: First step, add glacial acetic acid, the catalyst, and hydrogen peroxide into a reaction kettle, and then react at a temperature of 20 - 60 °C for 4 - 24 h to obtain a peracetic acid solution for standby; Second step, sequentially add the remaining components into the prepared peracetic acid solution under continuous stirring conditions, and then make up the volume with deionized water to obtain a microetching solution for copper alloy surfaces.

[0006] Further, the mass fraction of the hydrogen peroxide solution is 28-52%.

[0007] Further, the buffer is sodium acetate.

[0008] Further, the stabilizer is an organophosphorus stabilizer, including at least one of hydroxyethylidene diphosphonic acid and aminotrimethylene phosphonic acid.

[0009] Further, the corrosion inhibitor is at least one of benzotriazole and benzotriazole derivatives.

[0010] Further, the catalyst is a supported phosphotungstic heteropolyacid catalyst, and the preparation method of the supported phosphotungstic heteropolyacid catalyst includes the following steps: After mixing lanthanum nitrate hexahydrate, phosphotungstic heteropolyacid, triphenylphosphine, a carrier, and an ethanol solution evenly, stir for 8-12 h, then perform vacuum filtration. The obtained solid is dried to constant weight in an oven and then cooled to room temperature to obtain the supported phosphotungstic heteropolyacid catalyst.

[0011] Further, the carrier is a titanium silicalite molecular sieve, including at least one of TS-1, TS-2, and Ti-MCM-41.

[0012] Further, the ethanol solution is an ethanol aqueous solution with a volume fraction of 40-90%.

[0013] Further, by mass parts, the dosage ratios of lanthanum nitrate hexahydrate, phosphotungstic heteropolyacid, triphenylphosphine, the carrier, and the ethanol solution used are 6-12:18-26:8-14:90-124:800-1200.

[0014] The hydrogen peroxide-sulfuric acid system has a good roughening effect on copper ions and is environmentally friendly, but the stability of hydrogen peroxide is highly dependent on the pH of the solution. As the reaction proceeds, the copper ion concentration in the solution increases. Under the catalytic influence of copper ions, hydrogen peroxide will accelerate decomposition. Therefore, a large amount of sulfuric acid needs to be added to maintain the pH of the solution and reduce the concentration of copper ions through the common ion effect to reduce the decomposition of hydrogen peroxide. However, this also leads to a large amount of sulfate ions in the micro-etching solution. These sulfate ions remain in the slits on the surface of the copper alloy, resulting in the Giovanni effect to accelerate the corrosion of copper. In severe cases, it may even cause an open circuit on the circuit board. Peracetic acid is a peroxide with strong oxidizing properties and is environmentally friendly. In the prior art, it is mainly prepared by hydrogen peroxide and glacial acetic acid under the catalytic action of a strong acid catalyst. The oxidizing property of peracetic acid is stronger than that of hydrogen peroxide, and the copper alloy surface can be etched under weak acidic conditions. The peracetic acid prepared from hydrogen peroxide can greatly reduce the conductive properties of the hydrogen peroxide system micro-etching solution to reduce the Giovanni effect. The influence of the Nix effect, phosphotungstic heteropoly acid has excellent catalytic performance, low corrosion to equipment, and does not produce polluting gas, which is environmentally friendly. By loading phosphotungstic heteropoly acid on a solid phase carrier, the phosphotungstic heteropoly acid can also be recycled and the discharge of waste can be reduced. However, when etching, the micro-etching solution sometimes needs to be irradiated with the aid of ultraviolet light to change the etching rate, and the phosphotungstic heteropoly acid is easily decomposed under ultraviolet light, which not only causes the decomposition products to remain in the micro-etching solution, increasing the difficulty of waste liquid treatment, but also affects the recycling of the phosphotungstic heteropoly acid. In addition, after the effective decomposition of peracetic acid, acetic acid will be produced, which will cause the change of the overall pH of the micro-etching solution and thus affect the micro-etching rate and the uniformity of the micro-etching. The present invention uses lanthanum nitrate and triphenylphosphine to compound phosphotungstic heteropoly acid, and then the compounded product is loaded on the surface of a titanium silicon molecular sieve that absorbs ultraviolet light to improve the stability of the phosphotungstic heteropoly acid under ultraviolet light, and by adding a buffer, the pH of the entire micro-etching solution is stabilized, and the pH fluctuation caused by the acetic acid produced by the effective decomposition of peracetic acid is reduced.

[0015] Beneficial effects of the present invention: 1) The copper alloy surface micro-etching solution system of the present invention has a conjugated buffer system of sodium acetate / acetate ions, which can effectively maintain the stability of the pH of the micro-etching solution. In addition, a large amount of acetate ions can also have a better inhibitory effect on copper ions (the solubility of copper acetate is 7.2 g / 100 mL, which is much smaller than the solubility of copper sulfate 32 g / 100 mL), reducing the change in the decomposition rate of peracetic acid / hydrogen peroxide caused by pH fluctuation and metal ion catalysis, and effectively improving the etching uniformity.

[0016] 2) The content of strong acid ions in the micro-etching solution system of the present invention is much lower than that in conventional micro-etching solution systems. The anions in the system are mainly acetate (CH3COO -Anions, such as acetate ions, have weak conductivity and little promoting effect on microcurrent. Therefore, the micro-etching solution of the present invention can greatly reduce the conductivity of the micro-etching solution to inhibit the damage of the galvanic effect to copper alloys and improve the yield of products.

[0017] 3) A composite catalyst is obtained by compounding phosphotungstic heteropolyacid, lanthanum nitrate, and triphenylphosphine in the present invention, realizing the synergistic effect of Brønsted acid (phosphotungstic heteropolyacid) and Lewis acid (lanthanum nitrate), improving the catalytic effect, and through the coordination of triphenylphosphine and La 3+ to fix the structure of phosphotungstic heteropolyacid and increase the H-L orbital energy gap of phosphotungstic heteropolyacid, reducing the risk of the catalyst being decomposed by ultraviolet light. In addition, after compounding with triphenylphosphine, the dissolution loss rate of the supported catalyst in water can also be reduced, improving the service life of the compounded catalyst.

[0018] 4) The oxidant used in the micro-etching solution of the present invention is a hydrogen peroxide / peracetic acid compounding system. The compounding reduces the concentration of a single component and can also avoid excessive damage to the substrate by a single system. Utilizing the stage oxidation difference between hydrogen peroxide and peracetic acid, the synergistic effect of hydrogen peroxide and peracetic acid is realized, balancing the etching depth and improving the etching uniformity. Detailed implementation manners

[0019] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0020] Example 1 A supported phosphotungstic heteropolyacid catalyst is prepared by the following steps: By mass, 6 parts of lanthanum nitrate hexahydrate, 18 parts of phosphotungstic heteropolyacid, 8 parts of triphenylphosphine, 90 parts of TS-1, and 800 parts of an ethanol aqueous solution with a volume fraction of 90% are mixed evenly, stirred for 8 h, then vacuum filtered, and the obtained solid is dried to constant weight in an oven and cooled to room temperature to obtain the supported phosphotungstic heteropolyacid catalyst.

[0021] Example 2 A supported phosphotungstic heteropolyacid catalyst is prepared by the following steps: By mass, 9 parts of lanthanum nitrate hexahydrate, 22 parts of phosphotungstic heteropolyacid, 11 parts of triphenylphosphine, 107 parts of TS-2, and 1000 parts of an ethanol aqueous solution with a volume fraction of 65% are mixed evenly, stirred for 10 h, then vacuum filtered, and the obtained solid is dried to constant weight in an oven and cooled to room temperature to obtain the supported phosphotungstic heteropolyacid catalyst.

[0022] Example 3 A phosphotungstic heteropolyacid supported catalyst is prepared by the following steps: By mass, 12 parts of lanthanum nitrate hexahydrate, 26 parts of phosphotungstic heteropolyacid, 14 parts of triphenylphosphine, 124 parts of Ti-MCM-41, and 1200 parts of an ethanol aqueous solution with a volume fraction of 90% are mixed evenly, stirred for 12 h, then vacuum filtered, and the obtained solid is dried to constant weight in an oven and cooled to room temperature to obtain the phosphotungstic heteropolyacid supported catalyst.

[0023] Example 4 A copper alloy surface micro-etching solution contains the following components: 1.6 g / L of the phosphotungstic heteropolyacid supported catalyst obtained in Example 1, 15 g / L of glacial acetic acid, 28 g / L of a hydrogen peroxide solution with a mass fraction of 28%, 6 g / L of sodium acetate, 1 g / L of 1-hydroxyethylidene-1,1-diphosphonic acid, 1 g / L of benzotriazole, and the balance is deionized water; A preparation method of a copper alloy surface micro-etching solution includes the following steps: First step: Glacial acetic acid, the phosphotungstic heteropolyacid supported catalyst obtained in Example 1, and the hydrogen peroxide solution with a mass fraction of 28% are added to a reaction kettle, and then reacted at room temperature for 24 h to obtain a peracetic acid solution for standby; Second step: Under continuous stirring conditions, the remaining components are sequentially added to the prepared peracetic acid solution, and then fixed volume with deionized water to obtain a copper alloy surface micro-etching solution.

[0024] Example 5 A copper alloy surface micro-etching solution contains the following components: 3.2 g / L of the phosphotungstic heteropolyacid supported catalyst obtained in Example 2, 21 g / L of glacial acetic acid, 37 g / L of a hydrogen peroxide solution with a mass fraction of 40%, 8 g / L of sodium acetate, 2.5 g / L of 1-hydroxyethylidene-1,1-diphosphonic acid, 5.5 g / L of methylbenzotriazole, and the balance is deionized water; A preparation method of a copper alloy surface micro-etching solution includes the following steps: First step: Glacial acetic acid, the phosphotungstic heteropolyacid supported catalyst obtained in Example 2, and the hydrogen peroxide solution with a mass fraction of 40% are added to a reaction kettle, and then reacted at room temperature for 20 h to obtain a peracetic acid solution for standby; Second step: Under continuous stirring conditions, the remaining components are sequentially added to the prepared peracetic acid solution, and then fixed volume with deionized water to obtain a copper alloy surface micro-etching solution.

[0025] Example 6 A copper alloy surface micro-etching solution, comprising the following components: 4.8 g / L of the supported phosphotungstic heteropolyacid catalyst obtained in Example 3, 27 g / L of glacial acetic acid, 46 g / L of a hydrogen peroxide solution with a mass fraction of 52%, 10 g / L of sodium acetate, 4 g / L of aminotrimethylenephosphonic acid, 10 g / L of mercaptobenzotriazole, and the balance being deionized water; A preparation method of a copper alloy surface micro-etching solution, comprising the following steps: First step: Add glacial acetic acid, the supported phosphotungstic heteropolyacid catalyst obtained in Example 3, and the hydrogen peroxide solution with a mass fraction of 52% into a reaction kettle, and then react for 16 h at room temperature to obtain a peracetic acid solution for standby; Second step: Continuously stir and sequentially add the remaining components into the prepared peracetic acid solution, and then make up the volume to a certain volume with deionized water to obtain a copper alloy surface micro-etching solution.

[0026] Comparative Example 1 A copper alloy surface micro-etching solution, comprising the following components: 3.2 g / L of a phosphotungstic heteropolyacid catalyst, 21 g / L of glacial acetic acid, 37 g / L of a hydrogen peroxide solution with a mass fraction of 40%, 8 g / L of sodium acetate, 2.5 g / L of hydroxyethylidene diphosphonic acid, 5.5 g / L of methylbenzotriazole, and the balance being deionized water; A preparation method of a copper alloy surface micro-etching solution, comprising the following steps: First step: Add glacial acetic acid, the phosphotungstic heteropolyacid catalyst, and the hydrogen peroxide solution with a mass fraction of 40% into a reaction kettle, and then react for 20 h at room temperature to obtain a peracetic acid solution for standby; Second step: Continuously stir and sequentially add the remaining components into the prepared peracetic acid solution, and then make up the volume to a certain volume with deionized water to obtain a copper alloy surface micro-etching solution.

[0027] Comparative Example 2 This comparative example is a commercially available hydrogen peroxide-sulfuric acid system micro-etching solution.

[0028] Experimental Example 1 Perform micro-etching rate tests and galvanic effect tests on the copper alloy surface micro-etching solutions in Examples 4 to 6 and Comparative Example 1 and the commercially available hydrogen peroxide-sulfuric acid system micro-etching solution in Comparative Example 2 together.

[0029] Micro-etching rate: 50 mW / cm 2 Under the condition of ultraviolet light-assisted irradiation of 50 mW / cm, immerse the copper alloy circuit boards into each component micro-etching solution respectively, the etching temperature is 25 °C, take out each component copper alloy circuit board after complete immersion for 120 s, use a laser confocal scanning microscope to analyze and calculate the micro-etching rate, and observe the copper surface roughness; Galfani effect test: Connect a copper plate and a nickel plate with wires respectively, immerse the copper plate and the nickel plate in each component of the micro-etching solution, and use an ammeter to measure the Galvani current of each component of the micro-etching solution. The test results are shown in Table 1: Table 1 Experimental Example 2 Separate the supported phosphotungstic heteropolyacid catalyst in Examples 4-6, and use ultraviolet light with an intensity of 50 mW / cm 2 to irradiate for 1 h for simulated accelerated decomposition. Then, use the recovered supported phosphotungstic heteropolyacid catalyst to prepare a micro-etching solution for the copper alloy surface again, and conduct the test in Experimental Example 1. The test results are shown in Table 2.

[0030] Comparative Example 3 A micro-etching solution for copper alloy surface, comprising the following components: 1.6 g / L of the supported phosphotungstic heteropolyacid catalyst recovered in Example 4, 15 g / L of glacial acetic acid, 28 g / L of hydrogen peroxide solution with a mass fraction of 28%, 6 g / L of sodium acetate, 1 g / L of hydroxyethylidene diphosphonic acid, 1 g / L of benzotriazole, and the balance is deionized water; A preparation method of a micro-etching solution for copper alloy surface, comprising the following steps: First step: Add glacial acetic acid, the supported phosphotungstic heteropolyacid catalyst recovered in Example 4, and hydrogen peroxide solution with a mass fraction of 28% into a reaction kettle, and then react at room temperature for 24 h to obtain a peracetic acid solution for standby; Second step: Continuously stir and add the remaining components into the prepared peracetic acid solution in sequence, and then make up the volume with deionized water to obtain a micro-etching solution for copper alloy surface.

[0031] Comparative Example 4 A micro-etching solution for copper alloy surface, comprising the following components: 3.2 g / L of the supported phosphotungstic heteropolyacid catalyst recovered in Example 5, 21 g / L of glacial acetic acid, 37 g / L of hydrogen peroxide solution with a mass fraction of 40%, 8 g / L of sodium acetate, 2.5 g / L of hydroxyethylidene diphosphonic acid, 5.5 g / L of methylbenzotriazole, and the balance is deionized water; A preparation method of a micro-etching solution for copper alloy surface, comprising the following steps: First step: Add glacial acetic acid, the supported phosphotungstic heteropolyacid catalyst recovered in Example 5, and hydrogen peroxide solution with a mass fraction of 40% into a reaction kettle, and then react at room temperature for 20 h to obtain a peracetic acid solution for standby; Second step: Continuously stir and add the remaining components into the prepared peracetic acid solution in sequence, and then make up the volume with deionized water to obtain a micro-etching solution for copper alloy surface.

[0032] Comparative Example 5 A surface micro-etching solution for copper alloy, comprising the following components: 4.8 g / L of the supported phosphotungstic heteropolyacid catalyst recovered in Example 6, 27 g / L of glacial acetic acid, 46 g / L of hydrogen peroxide solution with a mass fraction of 52%, 10 g / L of sodium acetate, 4 g / L of aminotrimethylenephosphonic acid, 10 g / L of mercaptobenzotriazole, and the balance being deionized water; A preparation method of a surface micro-etching solution for copper alloy, comprising the following steps: First step: Add glacial acetic acid, the supported phosphotungstic heteropolyacid catalyst recovered in Example 6, and hydrogen peroxide solution with a mass fraction of 52% into a reaction kettle, and then react for 16 h at room temperature to obtain a peracetic acid solution for standby; Second step: Continuously stir and sequentially add the remaining components into the prepared peracetic acid solution, and then make up the volume with deionized water to obtain a surface micro-etching solution for copper alloy.

[0033] Table 2 It can be seen from Tables 1 to 2 that the galvanic currents of the micro-etching solutions of each component in Examples 4 to 6 and Comparative Examples 3 to 5 are much smaller than those of the commercially available hydrogen peroxide-sulfuric acid system micro-etching solution, and the surface etching is uniform. This shows that the micro-etching solution of the present invention has a good etching effect and can effectively inhibit the galvanic effect. Moreover, the supported phosphotungstic heteropolyacid catalyst used can be recycled multiple times, reducing resource waste. Comparative Example 1 is an unmodified supported phosphotungstic heteropolyacid catalyst. It can be seen that the catalytic effect of the unmodified supported phosphotungstic heteropolyacid catalyst is poor and it cannot be recycled. In summary, the surface micro-etching solution for copper alloy of the present invention can effectively inhibit the galvanic effect and has a uniform etching effect, and can be widely used in the field of the electronics industry.

[0034] The above has introduced in detail a surface micro-etching solution for copper alloy and its preparation method provided by the present invention. Specific examples are used herein to elaborate on the principle and implementation manner of the present invention. The description of the above examples is only used to help understand the method and its core idea of the present invention, including the best mode, and also enables any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combination method. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed by the present invention can be combined with each other in any way. The exhaustive description of these combinations is omitted in this specification only for the consideration of saving space and resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A copper alloy surface micro-etching solution, characterized in that: The raw materials include: catalyst, glacial acetic acid, hydrogen peroxide solution, buffer, stabilizer, corrosion inhibitor, and deionized water; The catalyst is a supported phosphotungstic heteropoly acid, and the preparation method of the supported phosphotungstic heteropoly acid is as follows: hexacontanium nitrate, phosphotungstic heteropoly acid, triphenylphosphine, a carrier and an ethanol solution are mixed and stirred to obtain a supported phosphotungstic heteropoly acid catalyst.

2. The copper alloy surface micro-etching solution according to claim 1, characterized in that: The carrier is titanium silicalite molecular sieve, including at least one of TS-1, TS-2 and Ti-MCM-41.

3. The copper alloy surface micro-etching solution according to claim 1, characterized in that: The ethanol solution is an ethanol aqueous solution with a volume fraction of 40 to 90%.

4. The copper alloy surface micro-etching solution according to claim 1, characterized in that: Calculated by weight, the usage ratio of lanthanum nitrate hexahydrate, phosphotungstic heteropoly acid, triphenylphosphine, carrier and ethanol solution used in the preparation of the loaded phosphotungstic heteropoly acid is 6-12:18-26:8-14:90-124:800-1200.

5. The copper alloy surface micro-etching solution according to claim 1, characterized in that: The copper alloy surface micro-etching solution comprises the following components: 1.6-4.8 g / L of catalyst, 15-27 g / L of glacial acetic acid, 28-46 g / L of hydrogen peroxide solution, 6-10 g / L of buffer, 1-4 g / L of stabilizer, 1-10 g / L of corrosion inhibitor, and the balance is deionized water.

6. A method for preparing a copper alloy surface micro-etching solution as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: The glacial acetic acid, the catalyst and the hydrogen peroxide solution are mixed and reacted at room temperature to obtain a peracetic acid solution, and then a buffer, a stabilizer and a corrosion inhibitor are added to the peracetic acid solution and the volume is fixed with deionized water to obtain a copper alloy surface micro-etching solution.

7. The method for preparing a copper alloy surface micro-etching solution according to claim 6, characterized in that: The mass fraction of the hydrogen peroxide solution is 28-52%.

8. The method for preparing a copper alloy surface micro-etching solution according to claim 6, characterized in that: The buffer is sodium acetate.

9. The method for preparing a copper alloy surface micro-etching solution according to claim 6, characterized in that: The stabilizer is an organic phosphorus stabilizer, including at least one of hydroxyethylidene diphosphonic acid and aminotrimethylene phosphonic acid.

10. The method for preparing a copper alloy surface micro-etching solution according to claim 6, characterized in that: The corrosion inhibitor is at least one of benzotriazole and benzotriazole derivatives.

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