Patter copper plating process:

Loading → Acid cleaner → Water rinse → Micro etch → Water rinse → Acid dip → Copper plating → Water inse → Acid dip → Tin plating → Water rinse 

→ Drying  → Unloading → Rack stripping → Water rinse 

The primary copper is what we call the full-plate electroplating, also called thickened copper, (after drilling, PTH and then thickened); the secondary copper refers to the pattern copper plating, and after the outer dry film is finished, thicken the copper on the track