Substances

The RoHS directive bans or strongly restricts the use of the following substances or classes of substances:

  • Lead (Pb)
  • Mercury (Hg)
  • Cadmium (Cd)
  • Hexavalent chromium (Cr(VI))
  • PBB (polybrominated biphenyls)
  • PBDE (polybrominated diphenyl ethers)

In practice it is impossible to completely avoid all these substances, i.e., to achieve zero concentration in the products. Therefore, maximum concentration values (MCV) have been given (these have been included in an amendment to the RoHS directive with document number C(2005) 3143, Commission Decision of August 18, 2005). These are, as expressed by weight in “homogeneous materials”:

  • Pb 0.1%
  • Hg 0.1%
  • Cd 0.01%
  • Cr(VI) 0.1%
  • PBB 0.1%
  • PBDE 0.1%

Where are the substances found?

Substance Occurrence
Cadmium Electroplating, NiCd batteries, plastics, arcing contacts and sensors
Hexavalent chromium (Cr6+)  Coatings on metals, primers for coated metals, hard chrome, metallising plastics
Lead Solders, termination and PCB coatings, glasses, electronic ceramics, in both passive and active devices
Mercury Batteries, fluorescent lamps, switches, sensors and relays
PBB and PBDE Flame retardants in a variety of plastics

It should be noted that there is a number of applications of the metals that are exempted from the requirements; these are specified in an Annex to the directive. For details, please refer to this text.

Many substances outside the RoHS directive are also of interest in EEE, either from an economic viewpoint or in relation to the environment or to health and safety. They can be divided into the following groups:

  • Organic compounds , usually synthetic in origin, e g PCB, phthalates, TBBA.
  • Inorganic compounds , such as asbestos.
  • Elements , mainly metals. These usually occur in their “pure” metallic state or in alloys, but may also be present in compounds (e g beryllium in ceramics, organotin compounds). They range from very common constituents (iron, copper, lead) to relatively rare elements such as indium. Some are of economic interest in recycling of EEE, including the noble metals gold, silver, platinum, and palladium.