Life cycle assesment on silicon and gallium arsenide transistors

3.2.1 Description………………………………………………………………………………………..9
3.2.2 Environmental impact…………………………………………………………………………..9
3.3 Energy consumption…………………………………………………………………………………..10
4.0 Gallium arsenide transistors……………………………………………………………………………....10
4.1 Extraction of arsenic…………………………………………………………………………………..12
4.2 Extraction of gallium……………………………………………………………………………...…..12
4.3 Manufacturing of the GaAs wafer………………………………………………………….………12
4.3.1 Description…………………………………………………………….…………………………12
4.3.2 Environmental impact…………………………………………………………………..……..12
4.4 Manufacturing process of the transistor…………………………………………………………..13
4.4.1 Description……………………………………………………………………………………….13
4.4.2 Environmental impact…………………………………………………………………..……..14
5.0 Common data………………………………………………………………………………………………..15
5.1 Encapsulation…………………………………………………………………………………………..15
5.2 Transports…………………………………………………………………………………………...…..15
5.3 Application………………………………………………………………………………………….…..16
6.0 Discards……………………………………………………………………………………………….………16
7.0 Impact assessment…………………………………………………………………………………………..17
7.1 Manufacturing of wafers………………………………………………………………….…………..17
7.2 Manufacturing process of the transistor……………………………………………………….…..17
7.3 Encapsulation and transportation……………………………………………………………………17
7.4 Application…………………………………………………………………………………………..…..17
8.0 Conclusion……………………………………………………………………………………………………19
9.0 References…………………………………………………………………………………………………....20
Abstract
Writing a life cycle assessment (LCA) involve trying to identify and quantify all of the environmental effect which can be put in contact with the product during its life cycle. The environmental impact is then evaluated and, if possible, an improvement analysis is made. Doing this gives us the products total environmental impact, and we can make a proper and accurate priority in lowering the environmental load. In this project it was carried out an LCA on two transistors made of silicon respectively gallium arsenide. The total environmental load has been evaluated with the Swedish EPS system, “Environmental Priority Strategies in Product design”. The total environmental load during the products whole life cycle has been included (“from cradle to grave”).
The life cycle of a transistor can be described in four phases; the extraction of raw material and making of semi product, the process of the functional unit, the application and finally the waste process. The actual process of the transistors can again be divided into production of transistors and encapsulation of transistors. The environmental index weight toward the consumption data shows that the main environmental load origins from the applications and customer use of the transistors (in both cases). If this phase is not reckoned with, the majority of the remaining environmental load is occupied mainly within the production of the transistors. Here we can see a larger environmental load for the gallium arsenide transistor.
1.0 Introduction
The purpose of this report is to compare the environmental effects of a...

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