Is there a universal marking available that can be put on the assembly indicating RoHS compliance and/or Pb-free?
No there is no such universal marking. The RoHS directive does not require any marking of final assemblies. The Soldertec institute and IPC have some advisory guidelines on marking. These can vary from symbols such as crossed out Pb in a red circle to a diamond with RoHS in black letters. A common symbol for the PCB would be the letter e with a number. Each number will indicate an alloy family. No marking would indicate SnPb.
