Some customers have inquired that in the production process of using tin plating brightener, the bonding force of the tin-plating layer is poor, So what should be paid attention to when pre-plating treatment?
Bigolly Technology made an analysis based on the field experience and the characteristics of the product Tin plating brightener Sn-807,Since the acid tin plating solution itself has no ability to degrease and remove oil,To plate a tin layer with good adhesion, when using a tin brightener, pay attention to the following points in the pre-plating treatment:
1. Copper parts and phosphor bronze parts can be degreasing by rolling, without pickling, but must be activated by dilute sulfuric acid before entering the plating tank.
2. Brass parts must be pre-plated with a layer of nickel or copper as a barrier to prevent the tin-plated layer of brass parts from appearing mottled or dark due to the diffusion of zinc.
3. The thickness of copper-plated brass parts and iron parts must be more than 3 μm.
4. When the rack plating parts cannot be pre-plated with copper or nickel, the parts should be impacted with a large current for 1 minute in the tank to avoid local chemical corrosion of the brass parts after tin plating.
5. Use copper and nickel as the bottom layer, Although it is an excellent barrier layer, it should be fully noted that the nickel layer is easy to passivate.When it is placed for too long or the activation is insufficient, the tin coating is prone to foaming, and even when it is aged at high temperature, foaming will also occur.
Therefore, we should pay attention to the above points when using tin plating brightener for production to ensure good bonding force of the tin-plated layer of the workpiece.