Footprint of an Ultra Low Power MCU

As the development of electronic goods continues to increase, it is imperative to understand the increasingly stringent environment, health and safety product requirements along with opportunities for sustainable production and consumption.ST commitment to eco-design is well established in EHS Decalogue. ST has identified Life Cycle Assessment (LCA) as the most appropriate methodology to calculate products carbon and water footprint and to highlight opportunities for ecological improvements in products design.

LCA is an internationally recognized approach that evaluates the potential environmental and human health impact associated with products and services throughout their life cycle, beginning with raw material extraction and including transportation, production, use, and end-of-life treatment. The LCA methodology is defined by ISO standards (ISO 14040, 2006; ISO 14044, 2006).

ST has performed several complete LCAs for representative products, in line with ISO standards. Here is presented, as an example, the results pertaining to a product family. The LCA results presented here are limited to the objectives, goal and scope of this communication tool; therefore the aim is not to be comprehensive and only four selected environmental indicators are presented.

It includes the raw material extraction, their transportation, the refining and forming into ready-to-use material. Both direct materials (i.e. back-end materials remaining in the product) and indirect materials (e.g. gases, chemicals, metals and silicon) are included in this life cycle stage.

It includes the manufacturing, the energy consumption, the water consumption, the air emissions, the water emissions and the solid wastes. The manufacturing of semiconductor devices can be divided in two main steps: the front-end step and the back-end step. In the front-end step, silicon is used to produce wafers and integrated circuits are then formed on the surface. In the back-end step, the package is manufactured to connect the silicon chip to the circuit board and to protect the chip from the external environment.

It includes an estimation of the transportation of the final product from manufacturing site to the warehouse.

Our products may be used in many different third party appliances. Only the electrical consumption of the chip itself is taken into account, considering a typical expected use scenario. An average European electricity mix is considered for calculations. The energy consumption of the whole final electronic appliance is not taken into account.

The study considers (in a conservative way) that the device is landfilled at the end-of-life.

Greenhouse gas emissions - It measures the potential impact on climate change from greenhouse gas emissions associated with a product, process or organization. Climate change is represented based on the International Panel on Climate Change’s 100-year weightings of the global warming potential of various substances (IPCC 2013). The impact metric is expressed in CO2-eq (grams of carbon dioxide equivalent).

Summer smog formation - It quantifies the potential for smog-forming gases that may produce photochemical oxidants. The photochemical oxidation, very often defined as summer smog, is the result of reactions that take place between nitrogen oxides (NOx) and volatile organic compounds (VOC) exposed to ultra violet (UV) radiation. The characterization factors are taken from ReCiPe (Goedkoop et al. 2008). This is reported in grams of NMVOC (non-methane volatile organic compounds).