Environmental Life-cycle Assessment in Microelectronics Packaging

Doctoral thesis, 2005

An increased understanding of the application of environmental Life-Cycle Assessment (LCA) methodologies in the microelectronics packaging area should help in developing environmentally sound product systems. The aim of the present thesis is to increase the knowledge of using LCA tools, methods and models, in application to current and new microelectronic products. A subgoal is to establish a better understanding of how to collect data to be used in a Life-Cycle Inventory (LCI) and environmentally assess the importance of the upstream processes. The objective has been to explore how variants of LCA could be used in microelectronics applications and the LCA software EcoLab and available data were utilised to analyse environmental loads. Different case studies were performed on (i) microelectronic products, (ii) substrate and soldering materials, and (iii) plating and soldering processes. The main emphasis has been on the upstream processes. Analysis of the results shows that the input data needed for environmental assessment of electronics applications comes from many different sources. An LCI data collection model applicable to most electronic products helps quantifying upstream processes. This is explained for a digital telephone. The global shift from Sn-Pb to Pb-free solder paste was modelled using attributional LCA and consequential LCA. It was found that the attributional and consequential methodologies yield complimentary knowledge about the environmental consequences of the shift. In this thesis, uncertainty estimation in LCI using Monte Carlo simulation was also investigated. The approach was applicable to small one parameter cradle-to-gate systems. There are strong indications that electrochemical pattern replication is more CO2 efficient than conventional photolithography, and that glass fiber enforced liquid crystalline polymers are more CO2 efficient than the corresponding brominated epoxy (FR4), polytetrafluoroethylene (Teflon®) and ceramic/glass tape. In addition to this, the effect of system expansion of manufacturing processes of the new packaging concept System-In-a-Package was addressed. This expansion of the upstream product system changes the relative environmental importance of manufacturing processes. Overall, environmental LCA are applicable to microelectronics packaging, but the assessments are hampered by the lack of ready available input LCI data.