RoHS stands for Restriction of Hazardous Substances. RoHS is the hot topic of the electronics industry today. RoHS is a well known term. Most of electronics engineers must have heard and used this term in their technical discussions. RoHS is an environmental directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment. RoHS was initiated in February 2003 by the European Union, which is formed by European countries. The main intention of RoHS initiative was to reduce hazardous substances in electrical and electronic equipment that will be sold in European countries. Later, the rest of the world had to follow the same to sell their electronics products globally.

RoHS has been in force since 1st July 2006. Some of the countries could not agree with the terms of RoHS directive, and they came up with their own RoHS directives (which are nearly equivalent to original RoHS) for the electronic products to be sold in their countries. Few such RoHS directives are China-RoHS, Japana-RoHS, California-RoHS, Korea-RoHS, Turkey-RoHS, Norway-RoHS, etc. Then the RoHS directive initiated by European Union is now being called as European-RoHS (EU-RoHS).

RoHS Directive in Brief

Under RoHS directive, there are only six substances restricted. They are:

  1. Lead (Pb)
  2. Mercury (Hg)
  3. Cadmium (Cd)
  4. Hexavalent chromium (Cr6+)
  5. Polybrominated biphenyls (PBB)
  6. Polybrominated diphenyl ether (PBDE)

But still, there are some exemptions to use these six substances with semiconductors. The restricted substances are allowed upto 0.1% (1000 PPM) except Cadmium, whereas Cadmium is allowed only 0.01% (100 PPM). The permitted concentration is per homogeneous material. “Homogeneous material” means a material that cannot be mechanically disjointed into different materials. For example, 0.1% of Lead (Pb) is allowed per weight of a component, and NOT per weight of an assembled board.

Among the above six, Lead (Pb) is a major one, which is largely used in electronics industry. That is why RoHS is often called as Lead-Free.

Advantages of RoHS

RoHS helps reduce damage to people and the environment. The use of lead-free solders and components has provided immediate health benefits to electronics industry workers in prototype and manufacturing operations.

Applicability of RoHS

RoHS is applicable to all electrical and electronic equipment. But still, there are some exemptions in applicability of RoHS directive.

The major exemptions of RoHS directive are:

  • Medical devices
  • Monitoring and control instruments
  • Fixed industrial plant and tools
  • Aerospace and military

A full list of exemptions is available at http://www.rohs.gov.uk/content.aspx?id=15

RoHS Summary

RoHS is a good initiative for protecting people and environment from serious hazards. But electronic equipment manufacturers are being forced to comply with RoHS, without showing the alternates to restricted materials. Many component manufacturers are simply playing with equipment manufacturers through frequent component obsolescence. I hope, electronics industry will find better RoHS alternates as soon as possible.