Published online by Cambridge University Press: 22 February 2011
The raw materials and clean-room processing techniques required to produce a low alpha-particle emitting insulating material have been investigated with the goal of producing a dense fired alumina ceramic with a reproducible, low alpha-particle flux (≤ 0.01 α/cm2hr). Various sources of A12 O3, MgO, and SiO2, the primary constituents of the alumina body, were tested for the alpha-particle emitting elements, U and Th, and for total alpha-particle flux. Many materials contain U concentrations with corresponding alpha-particle fluxes of 0.01α/cm2hr. Die pressing, filter casting and isopressing have been used under class 100 clean-room conditions to process powder compacts and the benefits and problems of each were evaluated. Analysis of the material before, at various stages during processing, and after firing has shown that dense fired Al2O3 ceramics can be produced with no detectable increase above that of the source powder in the U and Th contents, or the alpha-particle flux.