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Weak etching is the last pretreatment process before electroplating. It is used to remove the extremely thin oxide film on the surface of metal parts and achieve surface activation. Core features and functions Processing objects: The thin oxide film that is imperceptible to the naked eye is formed on the metal surface after strong etching and before electroplating. The essence is to activate the metal surface to ensure the bonding strength between the coating and the substrate. If this process is omitted, it will easily lead to electroplating peeling. Process characteristics: The etchant concentration is low, the treatment time is short (generally only a few seconds to 1 minute), and it is mostly performed at room temperature, making the operation easy. Common processing methods take ferrous metal processing as an example, which are divided into two mainstream processes.: chemical method: Use dilute hydrochloric acid or dilute sulfuric acid solution with a concentration of 3% to 5%, and the etching can be completed in 0.5 to 1 minute. electrochemical method: Anodizing is mostly used, using a dilute sulfuric acid solution with a concentration of 1% to 3%. The anode current density is controlled at 5~10A/dm². When hard chromium plating of steel parts can be completed directly in the chromium plating tank. Process Precautions: After etching is completed, it needs to be quickly cleaned and immediately transferred to the electroplating process. Do not stay in the air for a long time, let alone let the surface dry. ； If the composition of the weak etching solution is compatible with the subsequent plating solution, it can also be directly put into the tank without cleaning, which can improve production efficiency.