When it comes to making plated holes in PCBs,

1. Dipping the PCB into the sink or flushing it directly in order to allow the wall of hole to get sufficient wetting. After wetting, pay attention to that there are no bubbles in the wall of the hole;

2. Placing the PCB in the plating bath and letting the PCB sway back and forth in the slot (about 10 times) so that the hole wall is completely wetted by the plating solution.

3. Using a dovetail clamp to fix it in the center of the slot. For example, An A4 size PCB, whose plating current is 3.5A or so. BTW, the setting ratio of PCB plating current should be based on the size of PCB.