In the electroplating process of multilayer circuit boards, the chemical analysis of organic compounds and metal additives is becoming more and more complicated, and the reaction process is becoming more and more flexible. Many people often have the problem of scorching the edges of the board when electroplating multilayer circuit boards. The reasons for the scorching of the edges of multilayer circuit boards are usually as follows:

1. The 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 electroplating solution are low, which leads to the sintering of the layer.

3. Insufficient additives

In simple salt electroplating, if too many additives are added, the additive film produced by adsorption is too thick, and the main salt metal ions are difficult to penetrate the adsorption layer and discharge. H+ is a proton and is small in size, which is easy to penetrate the adsorption layer and discharge hydrogen. , So that the coating is easy to burn. In addition, too many additives have side effects, so any additives and brighteners must follow the principle of less and more.

4. Insufficient liquid circulation or mixing in the tank

Stirring is the main means to increase the speed of convective mass transfer. Using the cathode to move or rotate, there is a relative flow between the liquid layer on the surface of the workpiece and the plating solution a little farther away. The greater the stirring intensity, the better the convective mass transfer effect. When the stirring is insufficient, the surface liquid will flow unevenly, causing the coating of the multilayer circuit board 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 cathode 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 burnt.