LCA of electronic products

Intention, Goal, Scope, Background

A new paradigm called System-In-a-Package (SIP) is expected to represent the wave of future microsystem packaging and integration. No environmental assessment has been made of manufacturing processes for SIP and the purpose of this paper is to assess the upstream environmental impact of the process used by Chalmers to manufacture an electronic product using the SIP technology.

Objectives

This paper aims at an environmental assessment of a gallium arsenide (GaAs) Monolithic Microwave Integrated Circuit (MMIC) Switch Product based on a so-called SIP concept on a Liquid Crystalline Polymer (LCP) substrate. This study focuses on the identification of environmentally substantial upstream processes from cradle-to-gate for this product.

Methods

This work is based on a life cycle inventory model that has been developed earlier by the authors, and this model is now applied to the system including the straight-line manufacturing processes in the facilities of the Microtechnology Centre (MC2) at Chalmers University of Technology and the manufacturing processes of raw materials in the upstream processes. A main scenario was built in the LCA software EcoLab corresponding to the linear process in MC2 and other manufacturing processes were identified in the upstream which were used to develop the upstream process tree.

Results and Discussion

The spin coating of photoresistant material has the highest environmental impact within the system boundaries and the uncertainty of the results is estimated to be small. The exposure and development as well as deposition stages also give impacts, both for the copper and resistant material deposition. In the manufacturing processes inside MC2, the electricity consumption clearly dominates. The results predominantly reflect energy use, whereas toxicological aspects could not be reliably assessed due to lack of data and reliable methods, and therefore needs separate attention. Nevertheless, a toxicology assessment has been made with the Toxic Potential Indicator (TPI), which, compared to a telephone, showed a relatively large value for the switch. The toxic potential of the switch is higher per mass unit than a digital telephone.

Conclusions

The previously developed LCA data collection model worked well for the SIP product. The electricity consumption for the deposition machine and the solvent consumption in spin coating are the two most important hot spots. For greenhouse warming potential the acetone consumption in the spin coating steps is the most significant contributor, and the copper consumption in the copper deposition step dominates for abiotic resource depletion.

Recommendations and Outlook

It is recommended that the machines in the MC2 process lab used to manufacture the SIP product are studied for a longer period of time as it would make the electricity consumption figures more accurate. More electronic packaging concepts, such as System-on-a-chip (SOC) and multichip modules (MCM), should be evaluated and compared to SIP.