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Computer and Peripherals Material Project

Prepared by Meinhardt Infrastructure & Environment Group
for Environment Australia
October 2001
ISBN 0642547734

4. Material Production

4.1 Materials

Computers and peripheral equipment are comprised of a range of different materials, including different types and blends of plastic, ferrous and non-ferrous metals (including precious metals and heavy metals), glass, foam, rubber, carbon powder and additives (such as paints, coatings and fire retardants). The types and quantities of materials used in each unit will differ according to the type of equipment (e.g. PC, printer, scanner, etc), manufacturer, model and when it was made.

The materials described within this chapter are limited to those that are physically present within computers and peripheral equipment. A number of other materials, including some materials that pose environmental and health risks, will have been used in the manufacture and packaging of these finished products. These materials are outside the scope of this current project, however it is important to note that they are covered under separate arrangements with manufacturers. The manufacture of computers and peripheral equipment may be addressed through cleaner production initiatives between industry and Commonwealth or State authorities. The packaging of computers and peripheral equipment should be addressed through the National Packaging Covenant and the National Environment Protection (Used Packaging Materials) Measure.

The composition of a typical desktop computer has been determined in 1996 US studies; the results are outlined in Table 4.1. While laptop computers and LCD monitors have not been examined, their constituent materials are similar to those detailed in Table 4.1. These components are discussed in further detail in the following sections.

Table 4.1 Material Composition of PC
Material % Weight   Material % Weight
Silica 24.8803   Bismuth 0.0063
Plastics 22.9907 Chromium 0.0063
Iron 20.4712 Mercury 0.0022
Aluminium 14.1723 Germanium 0.0016
Copper 6.9287 Gold 0.0016
Lead 6.2988 Indium 0.0016
Zinc 2.2046 Ruthenium 0.0016
Tin 1.0078 Arsenic 0.0016
Nickel 0.8503 Selenium 0.0013
Barium 0.0315 Gallium 0.0013
Manganese 0.0315 Palladium 0.0003
Silver 0.0189 Europium 0.0002
Beryllium 0.0157 Niobium 0.0002
Cobalt 0.0157 Vanadium 0.0002
Tantalum 0.0157 Yttrium 0.0002
Titanium 0.0157 Platinum Trace
Antimony 0.0094 Rhodium Trace
Cadmium 0.0094 Terbium Trace

Source: Microelectrics and Computer Technology Corporation

4.1.1 Metals

It can be seen from Table 4.1 that many different base and precious metals are used in the construction of computer components. The likely form and use of metals that are of particular environmental concern are outlined below.

Other metals are often found in small quantities, usually in alloy form. Aluminium is often used in alloy with titanium, and iron is alloyed with nickel, cobalt and manganese in steel housings. Small or trace amounts of particular materials may be found in components that are bonded to PCBs (e.g. antimony in diodes, germanium and gallium in semiconductors, indium and selenium in rectifiers, ruthenium in resistors, and tantalum in capacitors). Phosphor activators and emitters within CRTs (in addition to the zinc or cadmium compounds mentioned above) include europium, terbium, vanadium and yttrium. Additional quantities of particular materials may be found within many different components (e.g. cobalt may be found in NiMH rechargeable batteries).

4.1.2 Plastic

The plastics referred to in Table 4.1 consist of the following resin types:

The amount of each of these plastics has been determined in studies by the American Plastics Council. These figures are provided in Table 4.2.

Table 4.2 Plastics in Computers
Plastic %
ABS 57
PPO 36
PVC Trace

Source: American Plastics Council

Other plastics may also be present in computers and peripheral equipment (e.g. cross-linked polyethylene [XLPE] may be used in place of PVC as an insulating coating for cables).

Other plastics may also be present in computers and peripheral equipment (e.g. cross-linked polyethylene [XLPE] may be used in place of PVC as an insulating coating for cables).

Some types of plastic may include metals and other elemental additives. For example, PVC sheaths for cabling include cadmium and lead stabilisers (i.e. additives to prevent the plastic from breaking down during use) and chloroparaffins have been used as softeners (i.e. additives to allow the plastic to remain flexible). Plastic housings made from ABS plastic may contain tetrabromobisophenol-A (TBBA), which is a brominated flame retardant.

4.1.3 Silica

Silica is the principal material used in the glass present in both CRTs and LCDs, and is also the basic material used to manufacture the majority of solid-state ICs (as exemplified by the term "silicon chip"). Glass of varying size and grade is used for copying plates within scanners, and the glass drums in toner cartridges for laser printers.

4.1.4 Other

Flame retardants, including organic halogenated or brominated compounds (e.g. TBBA) and inorganic compounds (e.g. antimony compounds), are used in the epoxy resin of PCBs to prevent fires. Polybrominated biphenyls (PBBs) have also been used as flame retardants, however sources indicate that their use in computer housings was discontinued between 7 and 10 years ago.

Antimony trioxide is commonly used with halogenated flame retardants as a synergist to achieve a high flame retardancy (EEB 2001).

There is some uncertainty (and argument) about the use of polychlorinated biphenyls in PCs. A principal use of polychlorinated biphenyls was for cooling and lubrication within older capacitors and power transformers. Whilst the OECD (2001) has indicated that capacitors containing polychlorinated biphenyls have been used in larger items of equipment (e.g. mainframe computers and large printers), their historic use in computers is less clear. This is illustrated by opposing statements made by the Electronic Industries Alliance (2000) and Silicon Valley Toxics Coalition (2001) regarding the presence or absence of polychlorinated biphenyls in computer equipment.

Trace amounts of liquid crystals are present in flat panel displays (e.g. approximately 0.42 gm are found in a 15" LCD monitor).

Inks are comprised of a pigment dissolved in an oil base with various additives to control the rate of drying, spreading and stickiness. Pigments have historically contained heavy metals (e.g. lead chromate or cadmium compounds) but have more recently contained organic and synthetic pigments. Black ink will normally be carbon-based. Toner is normally a powdered mixture of carbon black and plastic resin, and often includes waxes and a mineral carrier.

The list of materials given above is by no means exhaustive. Mechanical parts within individual PC components or peripheral equipment may include materials not specified in the previous sections, in order to carry out specific functions (e.g. rubber rollers that are used to feed paper through printers, and foam insulation). The materials specified above do represent the most common materials found in computers and peripheral equipment, and more importantly include those materials that have been commonly identified as posing environmental or health risks.

4.2 Environmental Impacts

It is important to note that the environmental and health risk of computer waste materials may be much larger than the quantities indicated by Table 4.1 might suggest. This is due to the overall volume of waste computer equipment disposed of each year, which compounds the small amount present in individual units into a total amount that may pose significant risks. Particular materials may also be of concern due to the manner in which they accumulate within the environment.

The materials that are of principal concern with regard to environmental and health risks include:

Other materials pose lesser risks that are specific to their handling in recycling operations (e.g. beryllium may be released into the air through the preparation of material samples for testing and will be harmful if inhaled, and lithium ion batteries pose a fire risk if shredded).

The adverse impacts of these materials upon both the environment and human health have been well documented by previous reports (EIA 2000, EEB 2001, EPA 2000, OECD 2001, SVTC 2001). Lead can damage the nervous system, accumulates in the environment and has high acute and chronic toxic effects on plants, animals and microorganisms. Cadmium and cadmium compounds are persistent, bioaccumulative and toxic with possible risk of irreversible effects on human health and the environment. It may cause cancer with prolonged exposure.

Inorganic mercury in water (e.g. landfill leachate) is transformed into methylated mercury in sediments. It is bioaccumulative and persistent, and can cause damage to the brain. Mercury alkyls and inorganic compounds are very toxic when inhaled, and can cause significant damage to health through cumulative impacts.

Chromium (VI) is easily absorbed and can produce various toxic effects within cells. In can cause severe allergic reactions, asthmatic bronchitis and potential damage to deoxyribonucleic acid (DNA) in cells.

Brominated flame retardants can be soluble in landfill leachate and are bioaccumulative and persistent. Nearly all flame retardants containing bromine and chlorine migrate and are volatile to a certain extent. They have been found in indoor dust and air through migration and evaporation from plastics.

Antimony trioxide (commonly used with halogenated flame retardants) decomposes when heated, producing toxic fumes (antimony) and can react under certain circumstances with hydrogen to produce a poisonous gas (stibine). Stibine affects the lungs, eyes, skin and respiratory tract; it is possibly carcinogenic and may affect the reproductive system.

Landfilling of computers and peripheral materials poses significant environmental and health risks, particularly through specific substances leaching into soil and groundwater. Soluble materials (e.g. the lead oxide solder in CRT frit, cadmium-based phosphors and the residual ink and toner from printer cartridges) may migrate into leachate. The leachate in landfills can be highly acidic and can dissolve materials that might otherwise remain stable (e.g. lead ions from broken CRT glass, or TBBA).

Documentation regarding the environmental and health risks associated with the disposal of computer and peripheral equipment often considers the effects of incineration. While incineration of the municipal waste stream is not established in Australia, the trend towards use of alternative waste technologies includes options for processing under high temperature. Combustion or high temperature processing may also occur during recovery of materials from waste computer and peripheral equipment. High temperature processing (e.g. smelting) may result in the release of dust containing oxides of beryllium, cadmium or lead. Lead fumes may also be released through heat treatment. Plastics extrusion may release bromine (from PBB and TBBA flame retarded plastics and PCBs) and chlorine (from PVC plastics), which are converted to chlorinated or brominated dibenzo dioxins and furans.

Plastic poses significant environmental risk for reasons other than toxicity, most notably due to the durability and longevity of material. This results in plastic materials remaining in landfill for very long periods of time. Considerable effort has been invested by many organisations worldwide to reduce the impact of plastic use on declining oil reserves and rapidly filling landfill space. Whilst many different types of plastic are produced to suit a wide range of applications, computers and peripheral equipment are a small yet significant part of the total product stream where recycling or recovery of materials will reduce current impacts.

It is noted that there will be additional environmental impacts arising from other parts of the total life cycle of computers and peripheral equipment (e.g. the extraction of natural resources for the production of materials and energy). However these aspects are outside the scope of this project.

4.3 Substitution of Hazardous Materials

The substitution of hazardous materials used in the manufacture of computers and peripheral equipment with more benign material has been investigated, with replacement at different stages of development and implementation for various materials.

Lead-free solders have been under development for over 10 years and some alternatives are available. Lead-free alloys generally have higher value, which may also encourage recovery of metals from end-of-life products. Alternatives for lead in solders are based on alloys of tin, silver, copper, bismuth and zinc, and are specific to the application. These include:

The latter solder (tin - zinc - bismuth) requires more development but is already in use by NEC in certain applications. A number of other companies involved in manufacture of computers or peripheral equipment have also instigated voluntary plans for elimination of lead-based solder (EEB 2001). These voluntary measures are detailed in Table 4.3 below.

Table 4.3 Voluntary Plans for Use of Lead-Free Solder
Company Details
Fujitsu High-end servers (step soldering): tin-silver-copper and tin-bismuth-silver (PCBs) used from 1999Lead-free finishing components required from October 2001 Use of tin-silver-copper and tin-bismuth-silver solders in all new products from December 2002
Hitachi Use of tin-silver-copper and tin-bismuth-silver solders in all products by March 2002
Matsushita Use of tin-silver-bismuth solders in optical disc drivers and mini-discs by September 1998Use of tin-silver-copper and tin-silver-bismuth solders in all new products by March 2003
NEC Notebook PCs: tin-zinc-bismuth solder used from 1999Full adoption of lead-free solder in all products by 2002 (substitution of tin-silver-copper and tin-silver-bismuth-copper solders)
Panasonic Full adoption of lead-free solder in 2001
Sony Lead-free finishing components required from January 2001 Use of lead-free solder in at least one model at each business unit from March 2001 Elimination of lead solders in all products, electronic components and maintenance services by March 2006

Source: EEB 2001

There are also some computer companies involved in the European Improved Design Life and Environmentally Aware Manufacturing of Electronic Assemblies by Lead-Free Soldering (IDEALS) project, including Philips and Siemens. This project initiated changes in 1999 in the use of lead solder by some European companies, although it is yet to be fully implemented across all participants.

Other alternatives to the use of solder may also exist. Cornell University announced in 2000 the development of a new epoxy (Alpha-Terp) which, while very strong at room temperature, starts to fall apart at approximately 190o C and can be dissolved with a common industrial solvent. Its use in PCBs as a replacement for solder has been promoted (Krause 2001).

Substitution of halogenated flame retardants has also been initiated in some areas. Aluminium trihydrate (ATH) and magnesium dihydrate (MDH) are two main substitutes used. They are mostly inert in landfills; ATH is insoluble and MDH has a very low solubility (EEB 2001). Industry initiatives include:

Sony also uses a phosphorous-nitrogen based flame retardant system for PCBs used in other types of electrical equipment that they manufacture (EEB 2001).

Material substitution initiatives within the CRT manufacturing sector include the removal of lead from CRT panel glass by the majority of CRT glass manufacturers within the USA, replacement of arsenic with sodium antimony in CRT glass, and the withdrawal of cadmium sulphide from use as a phosphor.

Some alternatives to the use of mercury have also been established. Hewlett Packard has chosen to use light emitting diodes (LEDs) instead of mercury lamps for their scanners. The company has also eliminated batteries by using flash memory technology (Krause 2001).

PVC is another problematic material which is being phased out in some computer and peripheral material applications. Sony has committed to reducing PVC use in wiring by 50% in all Japanese products by March 2001, and by March 2003 in all models made worldwide (EEB 2001). Alternatives to PVC include an ethene or ethene/propene co-polymer, and a polypropylene / styrene-ethylene-butene-styrene (PP/SEBS) blend.