NMRC: Research Highlights - Environment

The ICT industry is the world's largest and most rapidly expanding industry sector. As component production continually increases, a corresponding increase in toxicity is inevitable unless advanced research and development into eco-innovated electronics technologies and products is fostered. This very real need is recognised at national (EI and EPA initiatives) and European (EU WEEE directive) levels and strongly urged via global (e.g. Rio Summit Agenda 21) platforms. In parallel with this is the opportunity to use the sophistication of ICT technology to monitor and help preserve our green environment. The two research thrusts in this area at NMRC reflect the above position; environmentally superior electronics and the green environment (see Figure 34).

Figure 34:- Dr. Gabriel Crean, Director NMRC, Mr. Dan Wallace, T.D. Minister of State, Dept. of Environment & Local Government, Mr. Gary Relihan, Research Engineer, Environmental Sciences Laboratory and Prof. Brian Harvey Executive Vice-President for Research, UCC at the recent announcement of six new research projects.

Environmentally Superior Electronics

To date environmental issues in general have not been the primary focus of ICT-related technology research and development. This has led to materials, processes and equipment that are far from being environmentally optimal. However, the implementation of rigorous environmental standards and protocols is now forcing the entire ICT supply chain to overhaul their processes and usage of environmentally harmful materials. Research into areas that will foster sustainable eco-designed and eco-innovated ICT technologies and products is now vital to advance and maintain a competitive and innovative national ICT technology and product base in Ireland. This relatively new field of scientific research will result in the development of fundamentally new scientific knowledge in areas as diverse as environmentally-compatible electronics, green chemistries and bio-remediation (see Figure 35 which shows steps in processing og PCB assemblies for elemental analysis). Current research projects at NMRC include the following:-

• Environmentally Benign Wafer and Printed Circuit Board Cleaning
  Significant quantities of inorganic acids, bases and peroxides are consumed annually in the wet cleaning of silicon wafers. Similarly, significant chlorofluorocarbons and chlorinated chemicals are released annually from the degreasing of printed circuit boards. International treaties on the protection of the global environment stipulate that replacements for CFCs and HFCs must be introduced. NMRC is currently collaborating on developing solutions to reduce the environmental impact of cleaning processes. The use of carboxylic acids in metal removal from wafers has been developed in the past year, and is of comparable performance to a commercial clean in the removal of a range of typical contaminant metals. Supercritical fluid cleaning is under development, in collaboration with the Chemistry Department, UCC, as a means to replace a commercial organic removal clean, leading to a cleaning protocol free of the major inorganic chemical components currently used. This technology is also under development as a "green" alternative to standard degreasing cleans (CFCs or their replacements) for the printed circuit board industry.
• EXCIMET^TM Additive Metallisation Process
  NMRC has filed patents on a photo-selective metallisation process applicable to the metallisation of ceramics and encapsulant materials for the electronics industry. EXCIMET^TM is an additive, UV-assisted process that permits the photoselective activation of substrates for electroless plating. The process offers environmental benefits by providing an additive metallisation technology for electronic interconnect, with potentially large savings in the consumption of chemical metallisation solutions.
• Lead-free Solder and Assembly
  The new European directive on "Waste from Electrical and Electronic Equipment" includes aspects such as equipment take-back and material recycling but most immediately a ban on the use of lead. In anticipation of this directive, NMRC has been actively working with European manufacturers in the first pan-European research consortium dealing with the development of lead-free solder alloys and technology for the production of lead-free assembly processes for the electronic industry. This expertise is now being applied to support Irish companies in the evaluation and introduction of lead-free solders for anticipated future application in products (see Figure 36).

  Figure 36:- (A) is a SnPbAg on OSP-Cu metallisation solder joint and (B) is a SnAgCu on immersion Ag metallisation solder joint. Both have been power cycled for 5000 cycles. It is clear that both solder joints have cracked considerably around the component, but more damage is evident in the Pb containing joint.

• Additive Conductive Materials to Reduce Cost and Environmental Impact of Printed Circuit Board Manufacture
  NMRC is actively researching environmentally friendly PCB technologies. The objective is to significantly reduce chemically hazardous by-products from PCB production by using lower cost novel additive techniques. Two novel processes are being developed in parallel: a UV screen technology for economic, lower resolution (200micron), and a photo-defined technology for high resolution (50micron). The technologies target a broad range of applications, providing an effective, economically- competitive alternative to existing subtractive methods.

Green Environment

• Toxic Metals Sensors
  NMRC has developed transducers for monitoring significant environmental variables. Using self-assembled mono-layers and a chemically modified screen printed electrode process, trace level cadmium detection has been demonstrated in addition to the previously developed lead and copper (patent applied for) toxic metal sensors (see Figure shows Toxic-metal sensors for environmental analysis of water.).
• Water Based Printing Inks
  Pressure from health and safety authorities and environmental concerns are driving the printing industry towards the use of water-based printing ink and away from an organic solvent base. A drawback of these inks is that they have more variable acidity control which requires more supervision and thus generates increased losses. NMRC is working on developing technology for improved printing ink process control, using in- line pH monitoring. The NMRC contribution is the development a reference electrode for multi-day immersion in printing inks.
• Multiple Microelectrode Arrays for the Monitoring in the Environment, Food and Biomedical Sectors
  During 1999, NMRC was involved in two projects using microelectrode arrays for chemical analysis in the environment, food and biomedical sectors:-
  • Development of robust in-line, on-line and off-line sensors for the monitoring of alcohols and sugars in fermentation and process manufacturing sectors where the packaged sensor needs to be both biocompatible and sterilisable. NMRC has developed 3-D gated electrodes in platinum (figure shows SEM of section through 3D gated electrode array). An on-chip multiplexor and potentiostat were also developed.
  • Selective determination of heavy metal ions using functionalised microelectrode arrays. The research will provide analytical techniques that give early warning of emerging problems with metal pollution in natural bodies of water, in production line samples, and in drinking water, and will provide a mechanism by which the efficacy of remedial actions can be assessed (see Figure 39 below).

    Figure 39:- Glob top packaged microelectrode array for toxic metal analysis.

• Instrumentation
  NMRC is involved in the following projects in this area:-
  • An instrument for environmental toxic metal analysis. This instrument for rapid, field portable diagnostics will incorporate both microsystem and biosensor technologies for monitoring the effects of bioremediation on soil, plant, groundwater and leachate surrounding a site undergoing bioremediation. Toxic heavy metals (Cr, Cu, Cd, Zn, Hg, Ni, and Pb) and organics (PAHs and PCBs) are the target analytes.
  • An instrumentation system and control algorithms for monitoring and control of accelerated soil remediation sites. Parameters monitored include pH, temperature, BOD, dissolved oxygen, gas emissions and nutrient and toxic metal levels.
  • NMRC is currently working on the development of novel integrated micromachined gas sensor systems for home and public safety and on-line process monitoring of hydrocarbon containing gases. NMRC is developing robust sensing devices, including electrochemical sensors and biosensors for the real-time measurement of toxic heavy metal concentrations for various matrices of contaminated soils (see Figure 40 which shows flow-cell for chemical micro-analysis), groundwater bodies and surface waters. Eventually, the project will characterise the metal speciation in soil samples from six polluted sites through sequential fractionation.