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Design guide

Environment and Electronics article series:

Brief introduction to the restriction of harmful materials in electronics

Materials such as lead(Pb), Cadmium(Cd) , Mercury(Hg) which are popularly used in electronics are harmful to bio-life. Fall in the IQ level of the children, brain damage, kidney/thyroid damage are few harmful effects on human-life from these materials. The plants, sea-life and all the other bio on earth will degrade and suffer due to these chemicals.

After continuous protests by environment related organizations, the industry is now pressured to contain and finally fully-eliminate the use of hazardous substances.
The two great initiations in this direction are, WEEE (Waste Electrical and Electronic Equipment directive) and RoHS (Restriction on certain Hazardous Substances).

RoHS is a directive of the European Parliament (Directive 2002/95/EC; 27 January 2003) that, as its name implies, calls for manufacturers to restrict the use of hazardous substances in electrical equipment. The goal is to reduce human exposure to these materials through the ordinary use of products and to reduce the amount of hazardous material introduced to the environment when the products are eventually recycled or disposed of. The directive is legally binding on any company that wishes to sell product within the EU. Practically speaking, it applies to all equipment OEMs and all products worldwide as most will not wish to design and manufacture Europe-only products. Many OEMs have, in turn, made it binding on their suppliers if they want to sell to them.

The member states shall ensure that, new electrical and electronic equipment that will be sold in the market does not contain lead, mercury, cadmium, hexa-valent chromium, polybrominated biphenyls (PBB) and polybrominated diphenyls (PBDE). Except for Cadmium, the threshold level is 0.1% by weight of Homogeneous material and for Cadmium the threshold level is 0.01% by weight of Homogeneous material, effective from 1st Jul 2006.

Home appliances, computers, telecommunication, lighting and consumer equipments, toys, automatic dispensers, electronic and electric tools, electric light bulbs and luminaries in households are the industries covered by RoHS. Few exemptions granted are Lead in electronic ceramic parts, Lead in solders for servers, storage array systems, Lead in solders for network infrastructure equipment for switching, signalling, transmission as well as network transmission management for telecommunication, etc., These exceptions are to be reviewed every 4 years.

Most dangerous hazardous substances"

1. Lead (Pb) can be easily absorbed by living organisms (including humans) and can cause multiple health and environmental problems. Lead (Pb) is ubiquitous in almost all electronic equipments.

2. Cadmium (Cd) can be absorbed easily by organisms and ecosystems, will accumulate over time and is considered toxic and carcinogenic. The 2002/95/EC directive limits the maximum level of Cd at 100 ppm. Cadmium is used primarily in Cd-Ni batteries, but can also be electroplating applications as well as in pigment that can be added for coloring and/or stabilizers in plastics which are heat resistant. Other uses include solder and electroplating, as well as industrial lubricants.

3. Mercury (Hg) is a toxin that can easily be absorbed through contact via the skin or respiratory system, and Hg will accumulate in the bloodstream and eventually attack the central nervous system. Mercury (Hg) has historically been used in such devices as thermometers, barometers and other types of medical products, as well as automotive parts, batteries and fluorescent lighting fixtures.

4. Hexavalent Chromium (Cr6+) is a known carcinogen. Hexavalent Chromium-Cr6+ (also known as Cr VI) has been commonly used as a coating on a variety of materials, often to act as a corrosion inhibitor. Cr6+ can also be used in pigments, dyes, paints, inks, textiles, plastics and a host of other materials.
Ø Brominated flame retardants (BFRs), PBB and PBDE have been targeted by RoHS legislation as they are suspected to be carcinogenic. Additives have been used for years in commercially available plastics to make the polymers flame retardant and also in the connectors.

Continued in the next article: Alternates for the restricted hazardous substances

There will be a series of articles atleast for the 1st quarter of 2009 covering environment issues related to electronics.


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