Sometimes, due to the complexity of the multi-layer plating process, the cause of the failure and the method of troubleshooting need special attention. For example, a factory producing bicycle rims uses a cyanide-plated copper-plated bright nickel-plated decorative chrome process, which has a long history of production and a relatively mature production process. However, after a trial of equipment overhaul and bath treatment, it was discovered that the rims were chrome-plated and had a large area. After knowing that the rim of the rim was plated with bright nickel, there were noticeable bumps on the coating, which was caused by chrome plating. Internal stress increases and the coating bursts open. Plating explosives are mostly between the copper layer and the nickel layer, and the plating of the rims has a popping phenomenon.
The analysis and inspection is carried out in the multi-layer electroplating process (copper/nickel/chromium). For the cyanide copper plating process, the free NaCN content in the bath is found to be too high, which greatly increases the cathode polarization and leads to the cathode. There is a large amount of hydrogen precipitation, hydrogen precipitation has a good activation of the copper layer. CuCN was added to the plating solution to increase the copper ion content in the plating solution and reduce the content of free NaCN so that the free NaCN:Cu was 1:0.8, but the failure still existed.
Normally after the copper is cut off, a passive film can be formed on the surface of the copper layer. However, no film was observed on the spot. In order to confirm that under the normal conditions of copper plating formula and process conditions, non-copper-induced blasting, the technician will not energize several rims during copper plating, which is equivalent to direct nickel plating after pre-treatment. The failure has not been eliminated after the test.
From the bright nickel plating solution and process inspection, the reasons for the failure of bright nickel plating usually include: excessive brightener, excessive organic decomposition products, excessive metal impurities, and low boric acid content. Because the electroplating production line of this factory has just undergone routine maintenance treatment, there are no reasons why the brightener is excessive in the nickel plating bath, organic decomposition products are too much, and metal impurities are too much. According to the analysis report of the solution, the content of boric acid in the bath was 319/L, which was less than the 409/L to 459/L required by the process. When the boric acid is insufficient, the buffering performance of the bath is poor, the pH value in the cathode region is increased, the metal hydroxide or alkali salt adheres to the plating layer, and the phenomenon of peeling and the like easily occurs, but the boric acid content is added to the bath to 409/L. , plating explosion failure still exists. In order to verify the explosion failure caused by the reason not being nickel-plated, the technician put several rims directly after the nickel plating process on other production lines into the nickel tank for electroplating, resulting in good plating.
Further analysis of the copper-nickel process may be the cause of failure, thoroughly inspect the degreasing, activation, washing and other processes. From the scene, the washing tank is clean, the activation fluid is normal, and the equipment is operating normally. However, during the inspection, it was found that there was a piece of glass cloth floating on the surface of the activation liquid. It was understood that the activation tank was recoated with epoxy resin when the equipment was overhauled, and the addition of water and acid was used for only 1 day after coating. The activated liquid was pumped out and found that the epoxy resin coated on the wall was dissolved, the glass cloth was partially exposed on the wall, and the milky white turbid liquid was at the bottom of the tank. The activation tank was re-lined and dried thoroughly, and the plating was tested again. Skin breakdown is completely eliminated.
The reason for the failure was analyzed due to the fact that the wall material, the epoxy resin, was not completely cured, and the epoxy resin structure contained polar aliphatic hydroxyl groups, ether bonds, and reactive epoxy groups and dissolved in the sulfuric acid activation bath. The epoxy resin is adsorbed on the electrode interface, changing the nature of the interface, thereby affecting the electrode process, leading to electroplated layer explosion on the rim surface.
In fact, in the copper/nickel/chromium plating, the plating peeling is a relatively common failure, which is a comprehensive reflection of the poor quality of the combined plating layers. To prevent peeling of the coating, it must be analyzed and treated according to the specific conditions of the coating peeling.
For example, the phenomenon of peeling between the chrome layers may be caused by an interruption in the chrome plating process or the chrome plating layer is too thick. In this case, it can be checked whether the contact points of the electroplating equipment are in poor contact and shorten the chrome plating time (to avoid too thick chrome plating layer).
The phenomenon of peeling occurs between the nickel/chromium layers. Generally, the high current density at the parts is likely to peel off. The reason may be that the concentration of chromic acid in the chromium plating solution is too low; the temperature of the chromium solution is too low and the current density is too high; the sulfuric acid in the nickel plating solution Nickel, boric acid concentration is low; cathode current density is too high when nickel plating; bright nickel solution temperature is too low; bright nickel plating liquid titanium ions and so on.
In addition, the cause of the peeling of the nickel plating layer and the chrome plating layer is the imbalance of the brightener in the nickel plating solution; the nickel anode area is insufficient or poorly dissolved; the nickel plating liquid has a too high pH value; and the nickel-containing liquid is mixed with NO3- ions, Copper, iron, zinc, aluminum, etc.; Organic matter mixed in; Poor conductivity; Bipolar electrode; Passivation of nickel layer; Others such as chrome plating tank with oil;
Nickel layer peeling, which is often caused by intermittent electricity in the nickel plating process, of course, the pH value of the nickel plating solution is too high and the cathode current density is too large can cause peeling between the nickel layer.
Copper/nickel plating is peeled off. If cyanide copper is easily peeled off at high current densities, the reason may be: the copper ion content in the bath is low; the cathode current density is too high and the bath temperature is low; otherwise it may be The plating solution is mixed with oil or Cr6+ ions.
Others such as improper concentration of the activation solution and prolonged exposure of the copper layer to the air can also cause peeling between copper/nickel layers.
Peeling between the substrate and the copper layer is often caused by poor pretreatment of the copper plating. The main reasons are: excessive degreasing solution components, high sodium hydroxide concentration; low oil removal temperature, low current density, short oil removal time, etc.
The analysis and inspection is carried out in the multi-layer electroplating process (copper/nickel/chromium). For the cyanide copper plating process, the free NaCN content in the bath is found to be too high, which greatly increases the cathode polarization and leads to the cathode. There is a large amount of hydrogen precipitation, hydrogen precipitation has a good activation of the copper layer. CuCN was added to the plating solution to increase the copper ion content in the plating solution and reduce the content of free NaCN so that the free NaCN:Cu was 1:0.8, but the failure still existed.
Normally after the copper is cut off, a passive film can be formed on the surface of the copper layer. However, no film was observed on the spot. In order to confirm that under the normal conditions of copper plating formula and process conditions, non-copper-induced blasting, the technician will not energize several rims during copper plating, which is equivalent to direct nickel plating after pre-treatment. The failure has not been eliminated after the test.
From the bright nickel plating solution and process inspection, the reasons for the failure of bright nickel plating usually include: excessive brightener, excessive organic decomposition products, excessive metal impurities, and low boric acid content. Because the electroplating production line of this factory has just undergone routine maintenance treatment, there are no reasons why the brightener is excessive in the nickel plating bath, organic decomposition products are too much, and metal impurities are too much. According to the analysis report of the solution, the content of boric acid in the bath was 319/L, which was less than the 409/L to 459/L required by the process. When the boric acid is insufficient, the buffering performance of the bath is poor, the pH value in the cathode region is increased, the metal hydroxide or alkali salt adheres to the plating layer, and the phenomenon of peeling and the like easily occurs, but the boric acid content is added to the bath to 409/L. , plating explosion failure still exists. In order to verify the explosion failure caused by the reason not being nickel-plated, the technician put several rims directly after the nickel plating process on other production lines into the nickel tank for electroplating, resulting in good plating.
Further analysis of the copper-nickel process may be the cause of failure, thoroughly inspect the degreasing, activation, washing and other processes. From the scene, the washing tank is clean, the activation fluid is normal, and the equipment is operating normally. However, during the inspection, it was found that there was a piece of glass cloth floating on the surface of the activation liquid. It was understood that the activation tank was recoated with epoxy resin when the equipment was overhauled, and the addition of water and acid was used for only 1 day after coating. The activated liquid was pumped out and found that the epoxy resin coated on the wall was dissolved, the glass cloth was partially exposed on the wall, and the milky white turbid liquid was at the bottom of the tank. The activation tank was re-lined and dried thoroughly, and the plating was tested again. Skin breakdown is completely eliminated.
The reason for the failure was analyzed due to the fact that the wall material, the epoxy resin, was not completely cured, and the epoxy resin structure contained polar aliphatic hydroxyl groups, ether bonds, and reactive epoxy groups and dissolved in the sulfuric acid activation bath. The epoxy resin is adsorbed on the electrode interface, changing the nature of the interface, thereby affecting the electrode process, leading to electroplated layer explosion on the rim surface.
In fact, in the copper/nickel/chromium plating, the plating peeling is a relatively common failure, which is a comprehensive reflection of the poor quality of the combined plating layers. To prevent peeling of the coating, it must be analyzed and treated according to the specific conditions of the coating peeling.
For example, the phenomenon of peeling between the chrome layers may be caused by an interruption in the chrome plating process or the chrome plating layer is too thick. In this case, it can be checked whether the contact points of the electroplating equipment are in poor contact and shorten the chrome plating time (to avoid too thick chrome plating layer).
The phenomenon of peeling occurs between the nickel/chromium layers. Generally, the high current density at the parts is likely to peel off. The reason may be that the concentration of chromic acid in the chromium plating solution is too low; the temperature of the chromium solution is too low and the current density is too high; the sulfuric acid in the nickel plating solution Nickel, boric acid concentration is low; cathode current density is too high when nickel plating; bright nickel solution temperature is too low; bright nickel plating liquid titanium ions and so on.
In addition, the cause of the peeling of the nickel plating layer and the chrome plating layer is the imbalance of the brightener in the nickel plating solution; the nickel anode area is insufficient or poorly dissolved; the nickel plating liquid has a too high pH value; and the nickel-containing liquid is mixed with NO3- ions, Copper, iron, zinc, aluminum, etc.; Organic matter mixed in; Poor conductivity; Bipolar electrode; Passivation of nickel layer; Others such as chrome plating tank with oil;
Nickel layer peeling, which is often caused by intermittent electricity in the nickel plating process, of course, the pH value of the nickel plating solution is too high and the cathode current density is too large can cause peeling between the nickel layer.
Copper/nickel plating is peeled off. If cyanide copper is easily peeled off at high current densities, the reason may be: the copper ion content in the bath is low; the cathode current density is too high and the bath temperature is low; otherwise it may be The plating solution is mixed with oil or Cr6+ ions.
Others such as improper concentration of the activation solution and prolonged exposure of the copper layer to the air can also cause peeling between copper/nickel layers.
Peeling between the substrate and the copper layer is often caused by poor pretreatment of the copper plating. The main reasons are: excessive degreasing solution components, high sodium hydroxide concentration; low oil removal temperature, low current density, short oil removal time, etc.