Sustainable Microelectronics Packaging – Balancing Environmental, Cost and Reliability Issues

Microelectronics packaging is evolving in complexity to become a critical enabler of cost-effective semiconductor performance scaling across the spectrum of IOT, edge and cloud computing. As such, the justified focus on semiconductor environmental impact cannot ignore the contribution from the packaging sector. This paper seeks to provide an insight into both the environmental issues at hand and the challenges and opportunities for the sustainable development of microelectronic packaging technologies, where sustainability implies balancing the issues of cost, reliability and the environment in an effort to minimize resistance to change. Several development projects are discussed from the perspective of this balanced approach. Two opportunities to reduce energy consumption in solder reflow processes are presented. The first is low temperature soldering, where a process and structure is proposed for tin-bismuth (Sn-Bi) solder that can break the paradigm between temperature reduction and reliability. The second is localized reflow, where the advantages of laser assisted bonding (LAB) are discussed and its extension to large chips demonstrated. Development activities that touch upon reducing material consumption or replacing materials with more friendly alternatives are then reviewed. Plasma de-oxidation is shown to be an effective means to replace chemical fluxes and their cleaning during solder interconnection operations. Research results on additive manufacturing using electrohydrodynamic (EHD) printing demonstrate the potential to extend this technology to the 2–3 μm line/spacing requirements of advanced packaging redistribution layers, thus becoming a more sustainable alternative to photolithography for certain applications. Finally, efforts to replace toxic, petrochemical based epoxy resins with bio-sourced alternatives are introduced, showing promising preliminary properties using isosorbide-based resins.