The Removal of Tin from ITO-scrap via Ozonization

Abstract

Flat panel display applications for indium in the form of Indium Tin Oxide (ITO) are the most important end uses, more than one-half of the world’s indium consumption. The glass plate coated with ITO which is formed by doping indium oxide with approximately 10% of tin oxide, exhibits electrical conductivity without significantly affecting transparency, and has been used as transparent electrodes for flat panel displays. ITO films are generally fabricated by DC magnetron sputtering using ITO ceramic target. Magnetron sputtering is favoured because it is easily applied to large area with good uniformity. However, ITO targets should be replaced before a large portion of ITO material (60 ~ 70%) has been used because of race track formation. 4-6 So, it might be said that the recycling of unused ITO target is indispensable as indium is a trace element and very expensive. As shown in In1.82Sn0.18O3 obtained by doping indium oxide with approximately 10% of tin oxide, tin is the major impurity in recovery process of indium metal from ITO target-scrap. Indium and tin are chemically very similar and separation one from the other in solution is a knotty problem. Rapid separation of indium from tin by sublimation has been reported. 7