Green electronics focuses on eradication of harmful elements and components, and recycling of electronic products at the end of life.
Electronics has made life easier for us. But the omnipresence of electronics in modern life has a seamy underside. Certain materials used in electronic products are toxic and pose a threat to the environment. The situation is becoming serious with the increasing use of electronics.
Alarm bells have started ringing. And to tackle the situation, the industry is resorting to green electronics. Green electronics focuses on elimination of harmful elements and components, and recycling of electronic products at the end of life. Among the harmful elements are lead, cadmium, mercury and polybrominated diphenyl ether (PBDE).
The European Parliament has already passed a legislation that restricts use of lead and some other materials for the manufacture of electronic products till 2006.
Can we have a substitute for lead?
Around 90 per cent of all electronic components contain some lead. There are many technological and economic challenges before the initiative to produce lead-free components. Efforts are being made to find feasible and cost- effective ways to reduce lead in electronic products.
The electronic computer equipment is a complicated assembly of more than 1000 materials, many of which are highly toxic. These include chlorinated and brominate substances, toxic gases, toxic metals, photoactive and biologically active materials, acids, plastics and plastic additives. When computer waste is land filled or incinerated, the toxic materials and emissions contaminate the water resources and air. So recycling of electronic components has also assumed importance.
The ever-increasing functionality of information technology (IT) products is enabled by semiconductors. Semiconductors are the basis of all the electronic components and lead is the glue that binds all the semiconductor devices to make them work efficiently. Lead is used to a large extent in solders used in electronics. Without the use of lead solders and leaded glass, you would not be able to safely sit in front of your computer. Lead alloy solders enable your computer to send electronic data.
Lead was discarded from paints, ceramic glazers and plumbing solders years ago due to its poisoning effects, but the solders used in electronic applications were not targeted for such elimination because of their limited utilization and disposal. However, within the last decade, microelectronics has made significant strides resulting in widespread utilization and disposal of components containing lead solders.
It is estimated that one billion pounds of lead are contained in obsolete computers in the US alone. Two computers become obsolete for every three purchased. For the year 2005, this ratio is estimated at 1:1. That means we have to recycle computers as fast as we make them and that too efficiently. It will be costly to recycle these products because it is difficult to extract the usable metals, but the cost of recycling is minor compared to the cost of cleaning up if electronics are landfilled or incinerated.
But why lead is used in electronic components?
Lead can meet performance requirements in a cost-efficient manner. A tinlead solder alloy is usually used to join computer components to printed circuit boards (PCBs). Lead can be easily remoulded and refined.
Lead has the highest recycling rate of all the industrial metals in the world. In the US, around 80 per cent of all the lead is used in automotive batteries and more than 95 per cent of these batteries are recycled. Leads natural properties like low melting point, high strength, ductility; fatigue resistance, high thermal cycling, joint integrity, corrosion resistance, malleability and long life are well suited to electronics applications.
Lead is essential to the production of many highly technical products, from f octal monitors to fibre optics. It plays a vital role in space exploration, energy conservation and telecommunications.
Disposal of e-waste
e-waste can be disposed in three ways: incineration, landfilling and recycling.
Incineration. Incineration entails destroying the e-waste including computers and other electronic devices and components by burning. But this waste contributes significantly to heavy metals and halogen Ted substances. Because of the variety of different substances found together in electro scrap, incineration is particularly dangerous.
The introduction of waste from electrical and electronic equipment into incinerators results in high concentrations of metals, including heavy metals, in the slag, fly ash, flue gas and filter cake. More than 90 per cent of cadmium and lead put to an incinerator is found in the fly ash and more than 70 per cent of the mercury in the filter cake. Some producers send their electro scrap to cement kilns for use as an alternative to fuel. Smelting can present dangers similar to incineration.
Landfilling. Landfilling involves disposing the e-waste by burying it, especially as a method of filling in and reclaiming excavated pits. But it has become common knowledge that all landfills leak. Even the best state-of- the- art landfills dont remain completely tight throughout their lifetimes and a certain amount of chemical and metal leaching will occur. The situation is worse for older or uncontrolled dump sites.
Mercury leaches when certain electronic devices, such as circuit breakers, are destroyed. The same is true for PCBs from condensers. When brominates flame-retarded plastic or cadmium-containing plastics are landfilled, both PBDE and cadmium may leach into the soil and ground water. It has been found that significant amounts of lead ions are dissolved from broken lead containing glass, such as the cone glass of cathode ray tubes, when mixed with acid waters.
Recycling. Recycling of hazardous products has little environmental benefit -it simply moves the hazards into secondary products that eventually have to be disposed of. Unless the goal is to redesign the product to use non- hazardous materials, such recycling is a false solution.
The e-toxic components in computers include:
1. Computer circuit boards containing heavy metals like lead and cadmium
2. Computer batteries containing cadmium
3. Cathode ray tubes with lead oxide and barium
4. Brominated flame-retardants used on PCBs, cables and plastic casing
5. Polyvinyl chloride (PVC) coated copper cables and plastic computer casings that release highly toxic dioxins and furans when burnt to recover valuable metals
6. Mercury switches
7. Mercury in flat screens
8. Polychlorinated biphenyls present in older capacitors and transformers
Environmental problems during recycling are not linked to halogenated substances only. Hazardous emissions to the air also result from the recycling of e-waste containing heavy metals, such as lead and cadmium. These emissions could be significantly reduced by pretreatment operations.
Another problem with heavy metals and halogenated substances in untreated waste occurs during the shredding process. Since most waste is shredded without proper disassembly, hazardous substances, such as PCBs contained in capacitors, may be dispersed into the recovered metals and the shredder waste.
Consequences of using lead-free solders
Lead is very toxic to humans and can, among other things, cause serious chronic damage. Other metals such as silver (Ag), tin (Sn) and copper (Cu) have significantly lower toxic effects on the human body. From a health perspective, it therefore seems sound to avoid lead in tin solders if there is a risk of human exposure.
Use of modern production equipment, in which the soldering process takes place in closed systems, reduces or eliminates the risk of human exposure in work-related situations. However, there would always be a risk of exposure in maintenance and repair of production equipment. In relation to the working environment alone, it is therefore relevant to a certain extent to phase out alloys containing lead.
In the long term, humans are primarily exposed to lead via the environment. When soldered products are disposed of, a greater or smaller share of the material will end up in the waste system. When incinerated, lead contents become easily soluble, leading to increased leaching from the landfills where residues from waste incineration end up.
The significance of changing to lead-free alloys is uncertain seen from an ecotoxicological perspective, because it is uncertain how the alternative metals spread and degrade. Silver, for example, which is present in almost all lead-free alternatives, is far more toxic to aquatic organisms than lead.
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|Posted : 8/20/2005|