After lamination the PCB is plated with copper. This is done by electrodeposition during which up to 25µm of copper is added to the base copper foil. This can be done according to standard IPC class II or IPC class III. For prototypes we do IPC class III with no extra surcharge. During the plating process, the copper does not deposit evenly. Edges and areas close to the source of electricity attract more copper than other areas, especially the inside of holes where the flow of copper ions is limited. This means holes become harder to plate the deeper they are. Standard production panel plating delivers a typical aspect ratio of 6:1, but from our high-end PCB factories in both Europe and China, where they use reverse pulse plating, Azitech is experienced with aspect ratios of up to 24:1. We can also supply Sequential Build-Up (SBU) PCB boards in up to 6 pressing cycles, with high density interconnect micro vias in each cycle.
|SBU (Sequential lamination)||7+n+7||6+n+6|
|Max. PTH aspect ratio||24:1||16:1|
|Micro via aspect ratio||1:1||0.73:1|
|Max. hole plating thickness||25 µm||25 µm|
|Max. plating on base copper||25 µm||25 µm|
|Filled micro via planarity||5 µm||5 - 7 µm|