PCB prototype Circuit Boards Poor Plating Causes Analysis

1. Pinhole

Due to the adsorption of hydrogen on the surface of the plated part and not released that form pinhole on pcb prototype . The plating solution cannot be lubricated on the surface of the plating devices, so that the plating layer cannot be electrolyzed. As the thickness of the coating around the hydrogen evolution point increases, the hydrogen evolution point forms a pinhole. It features as a shiny round hole and sometimes with an upward small tail. When the wetting agent is absent in the plating solution and the current density is high, pinholes are easily formed on pcb prototype circuit board.

2, Pitting

The pitting is due to the unclean surface being coated, the adsorption of solid matter, or the suspension of solid matter in the plating solution. When it reaches the surface of the workpiece under the action of an electric field, it is adsorbed on it, which affects the electrolysis and embeds the solid matter in the plating layer, small bumps (pitting) are formed on pcb prototype circuit board. It is characterized by convexity, no lightening, and no fixed shape. In short, it’s because of dirty workpiece and the plating solution.

3, Airflow stripes

The airflow streaks are due to excessive additive or excessive cathode current density or high complexing agent, which reduces the cathode current efficiency and thus the amount of hydrogen evolution become large. If the plating solution flows slowly at the time, the cathode moves slowly, and the process of rising hydrogen on the surface of the workpiece affects the arrangement of the electrolysis crystals, forming a stripe of airflow from the bottom to the top.

4, Cover plating (exposed bottom)

The masking is due to the fact that the soft material of the surface of the workpiece is not removed, and the electrodeposition coating cannot be performed here. The on pcb prototype circuit board substrate is visible after plating, so it is called the transparent bottom (because the soft material is a translucent or transparent resin component).

5, Coating brittleness

After the SMD is formed after the SMD electroplated, it can be seen that there is cracking at the bend of the pin. When the nickel layer is cracked between the substrates, it is judged that the nickel layer is brittle on pcb prototype circuit board. When the tin layer and the nickel layer are cracked, it is determined that the tin layer is brittle. Most of the causes of brittleness are additives, excessive brighteners, or too much inorganic or organic impurities in the plating solution.