Life cycle thinking LCT aspects

38 Sustainable products • GHG emissions from PWBs can be also significantly reduced by selecting a PWB with less layers almost linear reduction of GHG emissions or by selecting a PWB with a different surface treatment than say, nickelgold NiAu. • Silver Ag in “lead-free” solder paste can have as much as ten times greater GHG emissions than solder paste compounds containing copper, lead or zinc. However, the move to lead-free solder may warrant the need for silver in solder paste. Note: Substitute materials for lead-free solders that meet ICT product technical specifications and are more environmentally benign are being researched within the ICT industry, and as they become commercially available, should be considered. • GHG emissions from smallersimpler components such as signal diodes, LEDs, surface mounted “chip” resistors and capacitors are very small and normally need not be a concern in reducing eco-impacts of printed wiring boards. • GHG emissions from aluminium used in cabinets, frames and chassis are significantly greater than the use of steel based on the metal’s manufacture from mined ores. However, this can be offset by selecting metals with high recycled content as well as deriving eco-life cycle benefits from aluminium’s lighter weight and the need for less protective finishes. See table below for GHG emissions from selected metals with different recycled contents. • GHG emissions from selected plastics e.g. polycarbonate, ABS, polystyrene are provided in the table below. Currently recycling technologies have not been adequately developed and deployed such that plastics with high recycled content can be easily specified. Material Estimated GHG emissions 10 , 11 kg CO 2 e extractionmfg stages to produce 1 kg of material Material finished product form – typical recycled content 0 recycled content 100 recycled content 12 Metal – aluminium Bayer refining, Halle-Heroult smelting 22.4 1.07 • Typical world – 40 • Extruded forms – up to 85 • Sheet products – up to 50-63 • Electronic components – 5 Metal – zinc electrolytic process 4.6 1.84 • Typical world – 36 • Die castings – 10 Metal – lead lead blast furnace 2.1 0.74 • Typical world – 47 • Battery plates – ~50 • Sheathingfoil – ~50 • Solder – 5 Metal – steel integrated route – BF and BOF 2.33 0.53 • Typical world – 47 • Structural forms – ~80 • Rolled sheet goods – 25 to 35 10 “Assessing the environmental impact of metal production processes”. T.E. Norgate, S. Jahanshahi, W.J. Rankin; CSIRO Minerals, Australia; 21 June 2006. 11 “The role of metals in sustainable development”. T.E. Norgate and W.J. Rankin; CSIRO Minerals; Green Processing; 2002. 12 Value attainable after 20 or more reiterative recycling.