Effect of Addition of Nanometric AlN Powder Synthesized in a Plasma Reactor in Sintering of Commercial AlN Powder

Abstract

Recently, attention has been focused to lower the sintering temperature of AlN, which is beneficial to cofiring multilayer substrates. In this work, the effect of addition of nanometric AlN powder (~50 nm) synthesized in a plasma reactor in sintering of commercial AlN powder (~1 micron) was investigated. Samples with 0, 25, 50, and 100% nanometric powder (NP) were sintered in a dilatometer at 1850 oC under nitrogen atmosphere. Sintered samples were analyzed based on the results of linear shrinkage, density, and microstructural characterization (XRD, SEM, and EDS). The increase of NP content enhanced the densification of AlN samples, by decreasing shrinkage starting temperature, decreasing maximum shrinkage rate temperature, and increasing total shrinkage. The samples prepared with mixed powders presented agglomerates, sometimes with circunferencial crack at the boundary, and elongated grains, identified as 27R polytypoid.