Beryllium copper heat treatment material electroplating process

Abstract

The invention discloses a beryllium copper heat treatment material electroplating process which sequentially comprises the following steps of ultrasonic oil removal, electrolytic oil removal, rust remover acid pickling, polishing, acid pickling activation, nickel plating and gold plating on a copper bottom layer on the surface of a base material, and the process can greatly improve the removal rate of surface oxide skin so as to improve the binding force between a subsequent plating layer and the surface of a beryllium copper workpiece.

Description

Technical Field

[0001] This invention relates to the field of electroplating technology, specifically to an electroplating process for beryllium copper heat treatment materials. Background Technology

[0002] In various connector applications, some raw materials require high-temperature treatment to improve their hardness. For example, beryllium copper can be treated at 310–400°C, increasing its hardness from 210–270 HV to 380–450 HV. However, after heat treatment, a dense and thick oxide film easily forms on the surface of beryllium copper. This oxide film mainly consists of beryllium oxide (BeO) and copper oxide (CuO), and is not only dense and stable but also insulating. Therefore, when electroplating is performed on heat-treated beryllium copper, the adhesion between the plating layer and the oxide film is poor, easily leading to problems such as peeling, bubbling, and flaking, ultimately making electroplating difficult.

[0003] Therefore, how to provide a stable beryllium copper heat treatment electroplating process has become an urgent technical problem to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a stable beryllium copper heat treatment electroplating process that can ensure a strong bond between the plating layer and the surface of the heat-treated beryllium copper material.

[0005] The technical solution adopted in this invention is: an electroplating process for beryllium copper heat treatment materials, comprising the following steps performed sequentially on a copper underlayer on the surface of a substrate: S1. Ultrasonic Degreasing: Ultrasonic degreasing is performed using a degreasing agent at a temperature range of 50-70℃. After degreasing, the substrate is rinsed with water. The added degreasing agent reduces the interfacial tension of the oil layer, promotes wetting, emulsification, dispersion, and saponification. Ultrasonic degreasing utilizes the "cavitation effect" generated by ultrasound in a liquid to penetrate the oil layer and impact the surface of the beryllium copper workpiece, causing the oil to be rapidly emulsified, dispersed, and peeled off. Here, the degreasing agent plays a role in chemical decomposition, while ultrasound plays a role in physical peeling; the two complement each other.

[0006] S2. Electrolytic Degreasing: Electrolytic degreasing is performed using degreasing powder at temperatures ranging from 50-70℃, with the current density controlled within the range of 10-30 A / dm. After degreasing, the substrate is rinsed with water. Electrolytic degreasing uses the beryllium copper workpiece as an electrode (cathode or anode) and applies direct current for degreasing. During the current-driven process, a large number of densely rising bubbles generate tremendous tearing, impact, and peeling forces on the oil layer, tearing the oil off the surface of the beryllium copper workpiece. Under the action of the current, the degreasing powder's ability to emulsify and disperse oil is significantly enhanced.

[0007] S3. Rust Removal Pickling: The rust remover is used to perform three pickling operations at a temperature of 50-70 ℃, with each pickling lasting 30-60 seconds. After pickling, the substrate is rinsed with water. The rust remover added in this invention mainly removes rust spots generated on the surface of copper materials after heat treatment. In addition, the rust remover can also chemically react with beryllium oxide and copper oxide on the surface oxide scale, directly dissolving and destroying the surface oxide scale on the beryllium copper workpiece, exposing a fresh, activated beryllium copper substrate with high surface energy, providing the basis for optimal adhesion of the subsequent electroplating layer.

[0008] S4. Polishing: Use polishing compound to polish the surface and remove the surface oxide scale. After polishing, rinse the substrate with water. Polishing will result in a more perfect and smooth substrate surface, which will prepare for subsequent electroplating.

[0009] S5. Acid pickling and activation: Use 15-20% sulfuric acid to acid pickle and activate the surface of beryllium copper material. After activation, rinse the substrate with water. This step is a weak acid activation, the purpose of which is to remove the extremely thin oxide film formed during the polishing process and reactivate the surface.

[0010] S6. Nickel plating: The substrate is placed in an electroplating solution for nickel plating. The solvent of the nickel plating solution is water. The nickel plating solution includes 80-120 g / L nickel sulfamate, 10-20 g / L nickel chloride and 30-45 g / L boric acid. The pH value of the nickel plating solution is adjusted to 3.5-4.5. After the nickel plating is completed, the substrate is rinsed with water. S7. Gold plating: Place the substrate in an electroplating solution for gold plating. The gold plating solution includes 8-10 g / L potassium gold cyanide, 40-50 g / L citric acid, and 5-10 g / L cobalt sulfate. Adjust the pH of the gold plating cobalt solution to 4-5. After the gold plating is completed, rinse the substrate with water.

[0011] Preferably, the degreasing agent has the following composition: Sodium hydroxide 10-30 g / L Sodium carbonate 30-40 g / L Sodium phosphate 80-100 g / L Sodium silicate 20-40 g / L Sodium lauryl thiolate 20-40 ml / L.

[0012] The sodium hydroxide and sodium carbonate in the degreasing agent primarily provide an alkaline environment, which reacts with the saponified greases through a saponification reaction. Sodium phosphate and sodium silicate help disperse solid contaminants and prevent redeposition. Sodium silicate also has a certain corrosion inhibitory effect, which can protect the surface of beryllium copper materials. The sodium lauryl thiolate mentioned above is a surfactant that can wetting, emulsifying, solubilizing, and suspending functions.

[0013] Preferably, in the S2 electrolytic degreasing process, the electroplating time is 2 minutes for the cathode and 1 minute for the anode. Cathode degreasing is fast and effective, producing small and numerous bubbles; anode degreasing can eliminate hydrogen that may penetrate the workpiece during cathode degreasing, preventing hydrogen embrittlement and dissolving trace impurities that may form on the surface of the beryllium copper workpiece.

[0014] Preferably, the degreasing powder has the following composition: Sodium hydroxide 30-40 g / L Sodium carbonate 30-40 g / L Sodium phosphate 50-70 g / L Sodium silicate 10-20 g / L.

[0015] The sodium hydroxide concentration in the above-mentioned degreasing powder is appropriate and will not corrode the surface of the beryllium copper workpiece; the added sodium silicate acts as an organic corrosion inhibitor, protecting the beryllium copper workpiece.

[0016] Preferably, the rust remover comprises the following components by weight percentage: Chloride 45-50% Inorganic acids 15-25% Sodium dodecylbenzene 25-35%.

[0017] The inorganic acid can be sulfuric acid or hydrochloric acid, and the added sodium dodecylbenzene is a surfactant that can help the inorganic acid better wet and penetrate into every micropore and defect of the surface oxide layer, thereby improving the reaction efficiency.

[0018] Preferably, the polishing agent has the following composition: Ammonium fluoride 80g / L 5-10 ml / L of hydrogen peroxide Sulfuric acid 30-50ml / L Nitric acid 10-20 ml / L.

[0019] Sulfuric acid in the polishing compound is the core acid, mainly used to dissolve the oxide scale on the surface of beryllium copper workpieces; ammonium fluoride plays a synergistic role in dissolving the oxide scale on the surface of beryllium copper workpieces; hydrogen peroxide and nitric acid can promote oxidation, accelerate the dissolution of the surface oxide scale and form a bright surface.

[0020] Preferably, in the S6 nickel plating, the thickness of the nickel underlayer is 1.5 to 6 μm.

[0021] Preferably, in the S6 nickel plating process, the nickel plating process parameters are: nickel plating solution temperature 40-60℃, current density 1.0-3.0 A / dm2, cathode movement 10-20 times / min, and plating time 3-8min.

[0022] Preferably, in the S7 gold plating, the thickness of the gold plating layer is 0.1 to 1 μm.

[0023] Preferably, in the S7 gold plating process, the gold plating process parameters are: gold plating solution temperature 40-60℃, current density 0.1-0.3 A / dm2, cathode movement 10-20 times / min, and electroplating time 0.5-1min.

[0024] Compared with the prior art, the present invention has the following advantages: The process of this invention utilizes ultrasonic degreasing and electrolytic degreasing to completely remove the oil layer on the surface of beryllium copper workpieces. This ensures that the subsequent rust remover and polishing agent can uniformly contact and corrode the surface oxide scale of the beryllium copper workpiece, significantly improving the removal rate of the surface oxide scale and thus enhancing the adhesion between the subsequent plating layer and the surface of the beryllium copper workpiece.

[0025] In the ultrasonic and electrolytic degreasing process of this invention, due to the presence of microcracks or weakly bonded particles in the surface oxide scale, the continuous cavitation effect of the ultrasonic waves and the impact of the violently released gas during electrolysis will loosen the surface oxide scale or create minor defects. This provides a smoother channel for the subsequent polishing agent and acid to penetrate and corrode the oxide film, further improving the removal rate of the surface oxide scale and further enhancing the adhesion between the plating layer and the beryllium copper workpiece surface. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the layer structure of the beryllium copper workpiece after processing according to the present invention.

[0027] The labels in the diagram indicate: 1-Copper base layer, 2-Nickel base layer, 3-Gold plating. Detailed Implementation

[0028] To enhance understanding of the present invention, it will be further described in detail below with reference to embodiments and accompanying drawings. The present invention can be implemented in the following ways: Example

[0029] An electroplating process for beryllium copper heat-treated materials includes the following steps performed sequentially on a copper underlayer on a substrate surface: S1. Ultrasonic Degreasing: Ultrasonic degreasing is performed using a degreasing agent at a temperature range of 60-70 ℃. The degreasing agent consists of the following components: sodium hydroxide 20 g / L, sodium carbonate 35 g / L, sodium phosphate 90 g / L, sodium silicate 30 g / L, and sodium lauryl thiolate (model SLS) 30 ml / L. After degreasing, the substrate is rinsed with water.

[0030] S2. Electrolytic degreasing: Electrolytic degreasing is performed using degreasing powder at a temperature range of 60-70 ℃, with the current density controlled within the range of 10-30 A / dm, and the electroplating time being 2 min for the cathode and 1 min for the anode; the composition of the degreasing powder is as follows: sodium hydroxide 35 g / L, sodium carbonate 35 g / L, sodium phosphate 60 g / L, sodium silicate 15 g / L; after degreasing, the substrate is rinsed with water.

[0031] S3. Rust Removal Pickling: The substrate is pickled three times using a rust remover at a temperature of 60-70℃. The rust remover comprises the following components by weight percentage: 50% chloride, 20% sulfuric acid, and 30% sodium dodecylbenzeneate (model: / LAS). After pickling, the substrate is rinsed with water.

[0032] S4. Polishing: Surface polishing is performed using a polishing agent to remove the surface oxide scale; the polishing agent has the following composition: ammonium bifluoride 80g / L, hydrogen peroxide 10ml / L, sulfuric acid 40ml / L, and nitric acid 15ml / L; after polishing, the substrate is rinsed with water. S5. Pickling and activation: The surface of the beryllium copper material is activated by pickling with 15% sulfuric acid. After activation, the substrate is rinsed with water. S6. Nickel Plating: The substrate is placed in an electroplating solution for nickel plating. The solvent of the nickel plating solution is water. The nickel plating solution includes 90 g / L nickel sulfamate, 15 g / L nickel chloride and 40 g / L boric acid. The pH value of the nickel plating solution is adjusted to 4. The nickel plating process parameters are: nickel plating solution temperature 40-60℃, current density 1.0-3.0 A / dm2, cathode movement 15 times / min, electroplating time 5min, and the thickness of the nickel underlayer is 3μm. After the nickel plating is completed, the substrate is rinsed with water. S7. Gold Plating: The substrate is placed in an electroplating solution for gold plating. The gold plating solution includes 10 g / L potassium gold cyanide, 45 g / L citric acid, and 8 g / L cobalt sulfate. The pH of the cobalt plating solution is adjusted to 4.5. The gold plating process parameters are: gold plating solution temperature 40–60℃, current density 0.1–0.3 A / dm², cathode movement 15 times / min, and electroplating time 1 min. The gold plating layer thickness is 0.5 μm. After gold plating, the substrate is rinsed with water. The layer structure of the beryllium copper workpiece after processing is as follows: Figure 1 As shown, from bottom to top, the layers are: copper base layer 1, nickel base layer 2, and gold plating layer 3. Example

[0033] The difference between Example 2 and Example 1 is that in steps S1, S2 and S3, the temperature is adjusted to be within the range of 40-60℃, while the other steps are the same as in Example 1.

[0034] Comparative Example Comparative Example 1 Electroplating was performed on the same heat-treated beryllium copper workpiece, and the process steps were roughly the same as in Example 1. The difference was that the S1 ultrasonic degreasing step was not performed.

[0035] Comparative Example 2 Electroplating was performed on the same heat-treated beryllium copper workpiece, and the process steps were roughly the same as in Example 1. The difference was that the S2 electrolytic degreasing step was not performed.

[0036] Comparative Example 3 Electroplating was performed on the same heat-treated beryllium copper workpiece, and the process steps were roughly the same as in Example 1. The difference was that the S3 rust remover pickling step was not performed.

[0037] Comparative Example 4 Electroplating was performed on the same heat-treated beryllium copper workpiece, and the process steps were roughly the same as in Example 1. The difference was that the S4 polishing step was not performed.

[0038] Comparative Example 5 Electroplating was performed on the same heat-treated beryllium copper workpiece, and the process steps were roughly the same as in Example 1. The difference was that the current density was controlled within the range of 5-10 A / dm in the S2 electrolytic degreasing step.

[0039] Comparative Example 6 Electroplating was performed using the same heat-treated beryllium copper workpiece, and the process steps were roughly the same as in Example 1. The difference was that the current density was controlled within the range of 30-40 A / dm in the S2 electrolytic degreasing step.

[0040] Performance testing Appearance: Visual inspection to check whether the gold plating layer 3 of the sample workpiece is continuous, bright, uniform, dense and consistent in color. If so, it indicates that the beryllium copper workpiece is qualified; otherwise, it is unqualified.

[0041] Adhesion Test (Scratch Method): Press a ruler firmly against the surface of the sample workpiece. Using a scribing tool, make a set of parallel cuts on the plating surface with uniform force and speed, with a cut spacing of 1 mm. On the original parallel cuts, make another set of parallel cuts at a 90-degree angle, forming a grid pattern. After scribing, gently clean away the debris generated during cutting with a blower. Take a piece of tape and apply it flat to the grid. Then, quickly peel off the tape within 0.5 to 1.0 seconds at an angle between 60° and 120°. Finally, observe whether there is any peeled plating adhering to the peeled tape, and observe the peeling condition of the plating within the squares of the grid area on the beryllium copper workpiece surface. The judgment criteria are divided into 0-5 levels, as follows: Level 0: The cut edges are completely smooth, with no squares missing.

[0042] Level 1: Slight peeling at the cutting intersection, with an affected area of ​​≤ 5%.

[0043] Level 2: Peeling at the cut edges and / or intersections, 5% < affected area ≤ 15%.

[0044] Level 3: Cut edges partially or completely peel off in large chunks, and / or the entire grid partially or completely falls off, with 15% < affected area ≤ 35%.

[0045] Level 4: The entire cut edge is peeled off in large chunks, and / or some entire squares are completely detached, with 35% < affected area ≤ 65%.

[0046] Level 5: Any degree of peeling exceeding Level 4.

[0047] Hydrogen embrittlement test: The electroplated sample workpiece is fixed on a special fixture and subjected to a constant load of 75% of the yield strength for 200 hours to check for fracture.

[0048] Corrosion resistance (neutral salt spray test): Place the sample workpiece in a salt spray test chamber and continuously spray it with a 5% sodium chloride solution according to the standard (ASTM B117). The temperature inside the chamber is kept constant at 35°C. After continuous spraying for 24h, 48h, and 96h, remove the sample workpiece and check the surface coating for rust.

[0049] The performance test results are shown in Table 1 below: Table 1 As can be seen from Example 1 and Comparative Example 1, the S1 ultrasonic degreasing step can improve the adhesion between the coating and the surface of the beryllium copper workpiece.

[0050] As can be seen from Example 1 and Comparative Example 2, the S2 electrolytic degreasing step can improve the adhesion between the plating layer and the surface of the beryllium copper workpiece.

[0051] As can be seen from Example 1 and Comparative Example 3, the pickling step with S3 rust remover is crucial for improving the adhesion between the plating layer and the surface of the beryllium copper workpiece.

[0052] As can be seen from Example 1 and Comparative Example 4, the S4 polishing step can improve the adhesion between the plating layer and the surface of the beryllium copper workpiece.

[0053] As can be seen from Example 1 and Comparative Examples 5 and 6, if the current density of the S2 electrolytic degreasing step is too low, the removal rate of the surface oxide scale will be reduced, thereby reducing the adhesion between the plating layer and the surface of the beryllium copper workpiece; if the current density of the S2 electrolytic degreasing step is too high, the surface of the beryllium copper workpiece will be easily corroded, resulting in poor corrosion resistance.

[0054] In summary, the electroplating process for beryllium copper heat treatment materials of the present invention can significantly improve the removal rate of surface oxide scale, thereby enhancing the adhesion between the subsequent plating layer and the surface of the beryllium copper workpiece.

[0055] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electroplating process for beryllium copper heat-treated materials, characterized in that, This includes the following steps performed sequentially on the copper underlayer on the substrate surface: S1. Ultrasonic degreasing: Ultrasonic degreasing is performed using a degreasing agent at a temperature range of 50-70℃. After degreasing, the substrate is rinsed with water. S2. Electrolytic degreasing: Electrolytic degreasing is performed using degreasing powder at a temperature range of 50-70 ℃, with the current density controlled within the range of 10-30A / dm. After degreasing, the substrate is rinsed with water. S3. Rust remover pickling: Use rust remover to pickle three times at a temperature of 50-70℃. After pickling, rinse the substrate with water. S4. Polishing: Use polishing compound to polish the surface to remove the surface oxide scale. After polishing, rinse the substrate with water. S5. Pickling and activation: Use 15-20% sulfuric acid to pickle and activate the surface of beryllium copper material. After activation, rinse the substrate with water. S6. Nickel plating: The substrate is placed in an electroplating solution for nickel plating. The nickel plating solution is water and includes 70-120 g / L nickel sulfamate, 10-20 g / L nickel chloride and 30-45 g / L boric acid. The pH of the nickel plating solution is adjusted to 3.5-4.

5. After the nickel plating is completed, the substrate is rinsed with water. S7. Gold plating: Place the substrate in an electroplating solution for gold plating. The gold plating solution includes 8-10 g / L potassium gold cyanide, 40-50 g / L citric acid, and 5-10 g / L cobalt sulfate. Adjust the pH of the gold plating cobalt solution to 4-5. After the gold plating is completed, rinse the substrate with water.

2. The electroplating process for beryllium copper heat-treated materials according to claim 1, characterized in that, The degreasing agent has the following composition: Sodium hydroxide 10-30 g / L Sodium carbonate 30-40 g / L Sodium phosphate 80-100 g / L Sodium silicate 20-40 g / L Sodium lauryl thiolate 20-40 ml / L.

3. The electroplating process for beryllium copper heat-treated materials according to claim 1 or 2, characterized in that, In the S2 electrolytic degreasing process, the electroplating time is 2 minutes for the cathode and 1 minute for the anode.

4. The electroplating process for beryllium copper heat-treated materials according to claim 3, characterized in that, The degreasing powder has the following composition: Sodium hydroxide 30-40 g / L Sodium carbonate 30-40 g / L Sodium phosphate 50-70 g / L Sodium silicate 10-20 g / L.

5. The electroplating process for beryllium copper heat-treated materials according to claim 1, 2, or 4, characterized in that, The rust remover comprises the following components by weight percentage: Chloride 45-50% Inorganic acids 15-25% Surfactant 25-35%.

6. The electroplating process for beryllium copper heat-treated materials according to claim 5, characterized in that, The polishing agent has the following composition: Ammonium fluoride 80g / L 5-10 ml / L of hydrogen peroxide Sulfuric acid 30-50ml / L Nitric acid 10-20 ml / L.

7. The electroplating process for beryllium copper heat-treated materials according to claim 1, 2, 4, or 6, characterized in that, In the S6 nickel plating, the thickness of the nickel underlayer is 1.5–6 μm.

8. The electroplating process for beryllium copper heat-treated materials according to claim 7, characterized in that, In the S6 nickel plating process, the nickel plating process parameters are as follows: nickel plating solution temperature 40-60℃, current density 5.0-10.0 A / dm2, cathode movement 10-20 times / min, and plating time 3-8min.

9. The electroplating process for beryllium copper heat-treated materials according to claim 1, 2, 4, 6, or 8, characterized in that, In the S7 gold plating, the thickness of the gold plating layer is 0.1 to 1 μm.

10. The electroplating process for beryllium copper heat-treated materials according to claim 9, characterized in that, In the S7 gold plating process, the gold plating process parameters are as follows: gold plating solution temperature 40-60℃, current density 0.1-0.3 A / dm2, cathode movement 10-20 times / min, and electroplating time 0.5-1min.

Images