Treatment process for surface coating of electronic circuit copper foil

Abstract

The invention relates to the technical field of electroplating production, in particular to a treatment process of an electronic circuit copper foil surface coating, and solves the problems that the uniformity, smoothness and fineness of the electronic circuit copper foil surface coating are poor and the heat resistance and corrosion resistance of the electronic circuit copper foil surface coating are finally reduced due to the fact that the electronic circuit copper foil adopts a pure zinc coating treatment mode at present. According to the process, the addition amount of zinc and nickel ions in the electroplating process of the electronic circuit copper foil is controlled, and meanwhile, the electroplating current of the copper foil in a high-temperature-resistant electroplating bath post-treatment machine is controlled, so that a plating layer with moderate density is formed on the surface of the copper foil when the concentration of the zinc ions in an electroplating mixed solution is 1.8-2.1 g / l, and the oxidation resistance of the electronic circuit copper foil is effectively ensured; meanwhile, when nickel ions are controlled to be 0.15-0.20 g / l, pores and defects of a copper foil coating are reduced to the minimum, the oxidation resistance of the copper foil is further improved, and the high temperature resistance and corrosion resistance of the electronic circuit copper foil are obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electroplating production, and particularly relates to a processing technology for the surface coating of electronic circuit copper foil. Background Art

[0002] Electronic circuit copper foil is a thin layer of copper foil deposited on the base layer of a circuit board. It is an important raw material for manufacturing copper clad laminates (CCL) and printed circuit boards (PCB), playing the role of a conductor. Electronic circuit copper foil is generally thicker than lithium battery copper foil, mostly between 12μm - 70μm. One side is rough and the other side is smooth. The smooth side is used for printed circuits, and the rough side is combined with the substrate. To improve the quality of electrolytic copper foil, ensure its heat resistance and corrosion resistance, and meet the actual needs of circuit board electronic component processing and manufacturing, and avoid the reaction of resin with bare copper under high temperature to produce water and separate from the substrate during the gasification process, heat-resistant coating treatment is required after the roughening layer treatment. The most common heat-resistant coating metal is zinc-based binary alloy. Currently, in the process of heat-resistant coating treatment of electronic circuit copper foil, due to the generally adopted treatment method of simple zinc coating, the uniformity, smoothness and fineness of the surface coating of electronic circuit copper foil are usually poor, ultimately reducing its heat resistance and corrosion resistance. Summary of the Invention

[0003] The present invention provides a processing technology for the surface coating of electronic circuit copper foil to solve the problem in the above background that the uniformity, smoothness and fineness of the surface coating of electronic circuit copper foil are poor due to the currently adopted treatment method of simple zinc coating, ultimately reducing its heat resistance and corrosion resistance.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A processing technology for the surface coating of electronic circuit copper foil includes the following steps: Step 1: First, add pure water to a high-temperature resistant electroplating solution circulation tank, and then add ZnSO 4 ·7H 2 O with zinc purity ≥ 22% into the pure water. After fully dissolving, control the Zn 2+ concentration in the mixed solution to be 1.8g / l - 2.1g / l.

[0005] Step 2: Add potassium pyrophosphate pentahydrate K 4 P 2 O 7 ·5H 2 O with purity ≥ 98% into the mixed solution in Step 1. After fully dissolving, control its concentration to be 58g / l - 62g / l.

[0006] Step 3: Continuously add electroplating grade NiSO 4 ·6H 2O, after being fully dissolved, control the Ni in the mixed solution 2+ concentration to be 0.15 g / l - 0.20 g / l.

[0007] Step 4: Add a sodium hydroxide solution with a concentration of 1.5 g / l to the electroplating mixed solution obtained in Step 3, and adjust the pH of the mixed solution to 11 - 11.5.

[0008] Step 5: Heat up the electroplating mixed solution obtained in Step 4 to 38°C - 42°C, and fill the heated mixed solution into a high-temperature resistant electroplating tank, and make it circulate at a flow rate of 7 m 3 / h - 9 m 3 / h.

[0009] Step 6: Load the pretreated electronic circuit copper foil into the post-treatment machine of the high-temperature resistant electroplating tank. Set the electroplating current of the high-temperature resistant electroplating tank as follows: the descending anode plate is 50 A - 60 A, the middle anode plate is 65 A - 80 A, and the ascending anode plate is 50 A - 60 A, and perform the feeding electroplating of the electronic circuit copper foil.

[0010] Further, the volume of pure water added to the high-temperature resistant electroplating solution circulation tank in Step 1 is 1.0 m 3 -1.5 m 3 , and the added mass of ZnSO 4 ·7H 2 O is 8 kg - 14 kg.

[0011] Further, the mass of potassium pyrophosphate pentahydrate K 4 P 2 O 7 ·5H 2 O added in Step 2 is 72.4 kg - 93.0 kg.

[0012] Further, the mass of electroplating grade NiSO 4 ·6H 2 O added in Step 3 is 0.67 kg - 1.40 kg.

[0013] Further, the volume of the sodium hydroxide solution added in Step 4 is 26 L - 40 L.

[0014] Further, the vehicle speed of the post-treatment machine of the high-temperature resistant electroplating tank in Step 6 is controlled to be 26 m / min - 32 m / min.

[0015] The present invention has the following beneficial effects: The present invention controls the addition amounts of zinc and nickel ions during the electroplating process of the copper foil for electronic circuits, and simultaneously controls the electroplating current of the copper foil in the post-treatment machine of the high-temperature resistant electroplating tank to be 50A - 60A for the descending anode plate, 65A - 80A for the middle anode plate, and 50A - 60A for the ascending anode plate. When the zinc ion concentration in the electroplating mixture is 1.8 - 2.1 g / l, a coating with a moderate density is formed on the surface of the copper foil, thereby effectively ensuring the antioxidant performance of the copper foil for electronic circuits.

[0016] When the nickel ion concentration in the electroplating mixture is controlled to be 0.15 - 0.20 g / l in the present invention, the pores and defects of the coating of the copper foil for electronic circuits are reduced to the lowest level, further enhancing the antioxidant performance of the copper foil for electronic circuits.

[0017] The present invention effectively avoids the problem that the current treatment method of using a pure zinc coating for the copper foil of electronic circuits results in poor uniformity, smoothness, and fineness of the coating on the surface of the copper foil of electronic circuits, ultimately reducing its heat resistance and corrosion resistance, and achieves a significant improvement in the high-temperature resistance and corrosion resistance of the copper foil of electronic circuits. Brief Description of the Drawings

[0018] Figure 1 It is a schematic process flow diagram of the present invention.

[0019] Figure 2 It is a diagram showing the appearance surface of the electroplated copper foil for electronic circuits before baking in the present invention.

[0020] Figure 3 It is a diagram showing the appearance surface of the electroplated copper foil for electronic circuits after baking in the present invention.

[0021] Figure 4 It is a diagram showing the rough surface appearance of the SEM image of the surface of the electroplated copper foil for electronic circuits after electroplating in the present invention.

[0022] Figure 5 It is a diagram showing the smooth surface appearance of the SEM image of the surface of the electroplated copper foil for electronic circuits after electroplating in the present invention.

[0023] Figure 6 It is a diagram showing the rough surface appearance of the SEM image of the surface of the electroplated copper foil for electronic circuits after baking and corrosion treatment in the present invention.

[0024] Figure 7 It is a diagram showing the smooth surface appearance of the SEM image of the surface of the electroplated copper foil for electronic circuits after baking and corrosion treatment in the present invention. Detailed Embodiments

[0025] The present invention will be further described below in conjunction with the drawings and specific embodiments.

[0026] Example 1 Add 1.3 m into the high-temperature resistant electroplating solution circulation tank 3Using pure water as the solute, add 10 kg of ZnSO₄·7H₂O with a Zn content of 24% into the circulation tank to make the Zn concentration in the solution 1.9 g / l. 4 ·7H 2 O in total, making the Zn concentration in the solution 1.9 g / l. 2+ Concentration is 1.9 g / l.

[0027] Continue to add 79.04 kg of K₃PO₄·5H₂O with a purity of 98% into the above-obtained electroplating mixture to make the K₃PO₄ concentration in the solution 60.14 g / l. 4 P 2 O 7 ·5H 2 O in total, making the K₃PO₄ concentration in the solution 60.14 g / l. 4 P 2 O 7 Concentration is 60.14 g / l.

[0028] Continue to add 0.8 kg of electroplating-grade NiSO₄·6H₂O into the obtained electroplating mixture to make the Ni concentration in the solution 0.18 g / l. 4 ·6H 2 O in total, making the Ni concentration in the solution 0.18 g / l. 2+ Concentration is 0.18 g / l.

[0029] After obtaining the above electroplating mixture, measure the pH value of the solution to be 3.4. Prepare 28 L of 1.5 g / l NaOH solution. After cooling to room temperature, add it to the electroplating mixture and measure the pH of the solution to be 11.3.

[0030] Heat the obtained electroplating mixture to 40.2 °C and fill the heated mixture into a high-temperature resistant electroplating tank. Start the solution circulation and keep the circulation flow rate in the high-temperature resistant electroplating tank at 8.2 m³ / h. 3 / h.

[0031] Then load the pretreated electronic circuit copper foil into the high-temperature resistant electroplating tank. Set the running speed of the post-treatment machine to 28 m / min. Set the electroplating current of the high-temperature resistant electroplating tank as follows: the descending anode plate is 55 A, the middle anode plate is 70 A, and the ascending anode plate is 55 A, and perform the feeding electroplating of the electronic circuit copper foil.

[0032] The electronic circuit copper foil electroplated through the above steps does not change color and has no oxidation black spots when baked at 220 °C for 120 min. When immersed in 10% dilute hydrochloric acid for 10 min, the anti-peeling strength attenuation rate is measured to be 3.4%. Obtain the Zn, Ni ion contents in the coating before and after electroplating treatment of the electronic circuit copper foil as shown in Table 1. 2+ 、Ni 2+ Ion content is shown in Table 1.

[0033] Table 1 Element content Zn% Ni% Before electroplating 0.0007 0.00004 After electroplating 0.013 0.0022 The numerical changes in the anti-peeling strength of the obtained copper foil before and after electroplating treatment are shown in Table 2.

[0034] Table 2 Item <![CDATA[Initial peel strength (kgf / mm 2 )]]> <![CDATA[Peel strength after soaking in 10% hydrochloric acid for 10 min (kgf / mm 2 )]]> Before electroplating treatment 1.48 1.22 After electroplating treatment 1.48 1.43 Example

[0035] Add 1 m 3 of pure water as a solute into the high-temperature resistant electroplating solution circulation tank, and then add 8 kg of ZnSO 4 ·7H 2 O with a Zn content of 22% into the circulation tank, so that the Zn 2+ concentration of the solution is 1.8 g / l.

[0036] Continue to add 98% pure K 4 P 2 O 7 ·5H 2 O totaling 72.4 kg to the above-obtained electroplating mixture solution, so that the K 4 P 2 O 7 concentration of the solution is 58 g / l.

[0037] Continue to add 0.67 kg of electroplating grade NiSO 4 ·6H 2 O to the obtained electroplating mixture solution, so that the Ni 2+ concentration of the solution is 0.15 g / l.

[0038] After obtaining the above electroplating mixture solution, measure the pH value of the solution to be 3.2. Prepare a total of 26 L of 1.5 g / l NaOH solution. After cooling to room temperature, add it to the electroplating mixture solution, and measure the pH of the solution to be 11.

[0039] Heat the obtained electroplating mixture solution to 38 °C, and fill the heated mixture solution into the high-temperature resistant electroplating tank. Start the solution circulation, and keep the circulation flow rate in the high-temperature resistant electroplating tank at 7 m 3 / h.

[0040] Then load the pretreated electronic circuit copper foil into the high-temperature resistant electroplating tank. Set the running speed of the post-treatment machine to 26 m / min. Set the electroplating current of the high-temperature resistant electroplating tank as follows: the descending anode plate is 50 A, the middle anode plate is 65 A, and the ascending anode plate is 50 A, and perform the feeding electroplating of the electronic circuit copper foil.

[0041] The electronic circuit copper foil electroplated through the above steps does not change color and has no oxidation black spots after baking at 220 °C for 120 min. Under the condition of soaking in 10% dilute hydrochloric acid for 10 min, the anti-peeling strength attenuation rate is measured to be 4.1%. Obtain the Zn 2+ , Ni 2+ ion contents in the coating before and after the electroplating treatment of the electronic circuit copper foil as shown in Table 3.

[0042] Table 3 Element content Zn% Ni% Before electroplating 0.00008 0.00001 After electroplating 0.022 0.0028 The numerical changes in the peel strength of the copper foil before and after the obtained electroplating treatment are shown in Table 4.

[0043] Table 4 Item <![CDATA[Initial peel strength (kgf / mm 2 )]]> <![CDATA[Peel strength after soaking in 10% hydrochloric acid for 10 min (kgf / mm 2 ) <!-- 3 -->]]> Before electroplating treatment 1.42 1.15 After electroplating treatment 1.42 1.36 Example

[0044] Add 1.5 m 3 of pure water as a solute into the high-temperature resistant electroplating solution circulation tank, and then add 14 kg of ZnSO 4 ·7H 2 O with a Zn content of 25% into the circulation tank, so that the Zn 2+ concentration of the solution is 2.1 g / l.

[0045] Continue to add 93.0 kg of K 4 P 2 O 7 ·5H 2 O with a purity of 98% into the above-obtained electroplating mixture, so that the K 4 P 2 O 7 concentration of the solution is 62 g / l.

[0046] Continue to add 1.4 kg of electroplating grade NiSO 4 ·6H 2 O into the obtained electroplating mixture, so that the Ni 2+ concentration of the solution is 0.2 g / l.

[0047] After obtaining the above electroplating mixture, the pH value of the solution is measured to be 3.5. Prepare 40 L of 1.5 g / l NaOH solution, and after cooling to room temperature, add it to the electroplating mixture, and the measured pH of the solution is 11.5.

[0048] Heat the obtained electroplating mixture to 42 °C, and fill the heated mixture into the high-temperature resistant electroplating tank, start the solution circulation, and keep the circulation flow rate in the high-temperature resistant electroplating tank at 9 m 3 / h.

[0049] Then load the pretreated electronic circuit copper foil into the high-temperature resistant electroplating tank, set the running speed of the post-treatment machine to 32 m / min, set the electroplating current of the high-temperature resistant electroplating tank as: the descending anode plate is 60 A, the middle anode plate is 80 A, the ascending anode plate is 60 A, and carry out the feeding electroplating of the electronic circuit copper foil.

[0050] The electroplated copper foil for electronic circuits produced through the above steps does not change color and has no oxidized black spots after baking at 220°C for 120 minutes. When immersed in 10% dilute hydrochloric acid for 10 minutes, the attenuation rate of its peel strength is measured to be 3.8%. The Zn 2+ and Ni 2+ ion contents in the coating layer before and after the electroplating treatment of the copper foil for electronic circuits are shown in Table 5.

[0051] Table 5 Element content Zn% Ni% Before electroplating 0.00008 0.00001 After electroplating 0.026 0.0025 The numerical changes in the peel strength of the copper foil before and after the electroplating treatment are shown in Table 6.

[0052] Table 6 Item <![CDATA[Initial peel strength (kgf / mm 2 )]]> <![CDATA[Peeling strength after soaking in 10% hydrochloric acid for 10 min (kgf / mm 2 )]]> Before electroplating treatment 1.50 1.16 After electroplating treatment 1.50 1.44 The electroplated copper foil for electronic circuits obtained in Examples 1 - 3 above is baked under the conditions of 220°C and 120 minutes. The appearance surface of the electroplated copper foil for electronic circuits before baking is as Figure 2 shown, and the appearance surface of the electroplated copper foil for electronic circuits after baking is as Figure 3 shown.

[0053] From Figure 2 and Figure 3 , it can be seen that after the electroplated copper foil for electronic circuits is baked at 220°C for 120 minutes, there is no obvious change in its appearance surface compared with that before baking. Thus, it is judged that the electroplated copper foil for electronic circuits after the electroplating treatment has excellent high-temperature resistance.

[0054] At the same time, when the electroplated copper foil for electronic circuits is immersed in 10% dilute hydrochloric acid for 10 minutes, its peel strength is measured to be lower than the initial peel strength. However, when the electroplated copper foil for electronic circuits after the electroplating treatment is immersed in 10% dilute hydrochloric acid for 10 minutes, its peel strength is significantly improved compared with that before the electroplating treatment. Therefore, it is concluded that after the electroplating treatment, the corrosion resistance of the electroplated copper foil for electronic circuits is significantly improved.

[0055] Scanning electron microscope image analysis The scanning electron microscope images of the rough and smooth surfaces of the copper foil treated by this electroplating treatment process are as Figure 4 and Figure 5 shown. It can be seen from the figure that the roughened electroplated layer on the rough surface of the copper foil is uniform, and the smooth surface is flat. After electroplating with this process, it does not have a negative impact on the roughened coating layer and the grain structure of the smooth surface of the previous electroplating. Moreover, since the Zn and Ni contents after plating can be controlled within 0.03% and 0.003% respectively, the coating layer is almost invisible after electroplating. Therefore, it is possible to avoid the negative impact of the electroplating process on the peel strength, tensile strength, and elongation rate of the copper foil.

[0056] Meanwhile, the scanning electron microscope images of the rough and smooth surfaces of the copper foil after being treated with this electroplating process, baked at 220°C for 120 minutes, and immersed in 10% dilute hydrochloric acid for 10 minutes are as follows Figure 6 , Figure 7 shown. By Figure 6 , 7 compared with Figure 4 , 5 contrastive observation, it can be found that after a long time of baking and being treated with dilute hydrochloric acid corrosion, the grain morphology of the copper foil surface has no obvious change compared with that before treatment, and the roughened layer still adheres evenly and stably, and no acid etching marks are generated on the smooth surface.

[0057] In summary, after adopting this electroplating process for the electronic circuit copper foil, good high-temperature heat resistance and corrosion resistance can be obtained, and after high-temperature baking, the copper foil can still maintain good corrosion resistance.

Claims

1. A treatment process for the surface plating of copper foil of electronic circuits, characterized in that: The following steps are involved: Step 1: First, add pure water to the high temperature resistant electroplating solution circulation tank, then add ZnSO4·7H2O with zinc purity ≥22% to the pure water, and after fully dissolving, control the Zn content in the mixed solution. 2+ Concentration is 1.8g / l-2.1g / l; Step 2: Add potassium pyrophosphate pentahydrate K4P2O7·5H2O with a purity of ≥98% to the mixed solution of step 1, and after fully dissolving, control the concentration to be 58g / l-62g / l; Step 3: Continue to add electroplating grade NiSO4·6H2O to the mixed solution in step 2. After it is fully dissolved, control the Ni content in the mixed solution. 2+ Concentration is 0.15g / l-0.20g / l; Step 4, adding a sodium hydroxide solution with a concentration of 1.5 g / l to the electroplating mixed solution obtained in step 3, and adjusting the pH of the mixed solution to 11-11.5; Step 5, heating the electroplating mixed solution obtained in step 4 to 38°C-42°C, and charging the heated mixed solution into a high temperature resistant electroplating tank, so that it circulates at a flow rate of 7m³ / h-9m³ / h; Step 6: Load the pretreated electronic circuit copper foil into a high temperature resistant electroplating tank post-processor. The electroplating current of the high temperature resistant electroplating tank is set to: descending anode plate 50A-60A, middle anode plate 65A-80A, ascending anode plate 50A-60A, and the electronic circuit copper foil is fed for electroplating.

2. The process for treating the surface plating of the copper foil of an electronic circuit according to claim 1, characterized in that: In the step 1, the volume of pure water added to the high temperature resistant electroplating solution circulation tank is 1.0m³-1.5m³, and the mass of ZnSO4·7H2O added is 8kg-14kg.

3. The processing technology of the surface plating of the copper foil of the electronic circuit according to claim 1 is characterized by: The mass of potassium pyrophosphate pentahydrate K4P2O7·5H2O added in step 2 is 72.4kg-93.0kg.

4. The processing technology for the surface plating of the copper foil of an electronic circuit according to claim 1 is characterized by: The mass of the electroplating grade NiSO4·6H2O added in step 3 is 0.67kg-1.40kg.

5. The processing technology for the surface plating of the copper foil of an electronic circuit according to claim 1 is characterized by: The volume of the sodium hydroxide solution added in step 4 is 26L-40L.

6. The processing technology for treating the surface plating of the copper foil of an electronic circuit according to claim 1, characterized in that: In step 6, the speed of the high temperature resistant electroplating tank post-processing machine is controlled to be 26m / min-32m / min.

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