Differential Copper PCBs require different heights or weights of copper on the same layer.
- Sculptured Flex
- Bump Plated
- Pedestal Plated
Sculptured Flex circuits are formed to shape and have exposed metal fingers that allow for bare metal connections (like a plug-in) and remain strong at the solder joint formation. Sculptured fingers provide a more reliable alternative to mechanically-fastened crimp pins. They can be custom-made to have copper conductors varying in depth and thickness. The copper is thin at the most flexible part of the circuit and thick at the interconnection point. They elegantly combine a flex circuit and a pin connector to preserve space while reducing assembly time. The sequential etch-down process requires a great deal of pre-engineering and process control.
Bump Plated PCBs make use of heavily-plated SMT pads (plated-up > 5 mils) that allow the board to be soldered to another PCB. Hence, these boards tend to be smaller as they are a discrete component that is assembled to another board.