ROHS CERTIFICATION CONSULTANCY SERVICES IN DELHI. What Is RoHS? The definition and aim of the RoHS directive is quite simple. The RoHS directive aims to restrict certain dangerous substances commonly used in electronic and electronic equipment.RoHS is often referred to as the "lead-free directive, " but it restricts the use of the following six substances: Lead (Pb) Mercury (Hg) Cadmium (Cd) Hexavalent chromium (Cr6+) Polybrominated biphenyls (PBB) Polybrominated diphenyl ether (PBDE)