Why does the edge of the multilayer circuit board burn when electroplating?
In the electroplating process of multilayer circuit board , the chemical analysis of organic compounds and metal additives is becoming more and more complex, and the reaction process is becoming more and more flexible. Many people often have the problem of board edge scorching when electroplating multilayer circuit board . The reasons for the edge scorching of multilayer circuit board are usually as follows:
1. Tin-lead anode is too long
The anode is too long, the workpiece is too short, and the lower end of the workpiece is too dense and easy to burn.
2. Insufficient tin and lead content
The metal content is insufficient, the current is relatively large, H∞ is easy to discharge, and the diffusion and electromigration speed of the plating solution is low, resulting in the sintering of the layer.
3. Insufficient additive
In simple salt electroplating, if too much additive is added, the additive film produced by adsorption is too thick, and the main salt metal ions are difficult to penetrate into the adsorption layer and discharge, H is a proton, Small volume, easy to penetrate the adsorption layer and discharge hydrogen evolution, making the coating easy to burn. In addition, too many additives have side effects, so any additives and brighteners should follow the principle of less and more.
4. Insufficient liquid circulation or stirring in the tank
Stirring is the main means to increase the convective mass transfer rate. uses the cathode to move or rotate, and relative flow occurs between the liquid layer on the surface of the workpiece and the plating solution slightly away. The greater the stirring intensity, the better the convective mass transfer effect. When the stirring is insufficient, the surface liquid flows unevenly, causing the multilayer circuit board coating to burn.
5. High current density
If the current density is too low, the grain size of the coating will become coarse, and the coating cannot even be deposited. When the current density increases, the cathodic polarization increases, which makes the coating dense and the plating rate increases. However, if the current density is too high, the multilayer circuit board coating will turn black or scorch.
Multi-layer circuit board, multi-layer circuit board, blind buried hole circuit board, thick copper circuit board
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