ALUMINA POWDER, PROCESS FOR PRODUCING THE SAME, AND COMPOSITION CONTAINING THE SAME

摘要

An alumina powder having further improved reliability concerning moisture resistance; a process for producing the powder; and a composition containing the powder, especially an encapsulating material for semiconductors. The alumina powder in a 100-hour ultrapure-water extraction test at 150°C has an Na+ amount of 20 ppm or smaller. Alternatively, the alumina powder is one which in a 100-hour ultrapure-water extraction test at 150°C has a total amount of Li+, Na+, and K+ of 20 ppm or smaller, and which includes particles having an average particle diameter smaller than 45 µm, these particles having an average roundness of 0.95 or higher, and has an average particle diameter of 100 µm or smaller. The process for alumina powder production is characterized by heat-treating pulverized fused alumina in a flame. The composition comprises a resin or rubber which contains either of these alumina powders.