Characterization Of Glass-Ceramic Dielectric Thick Films With Cu Conductors for Multilayer Packages

Abstract

AbstractCompatibility and characteristics of multilayer dielectric thick films with Cu interlayers are influenced by composition and processing parameters. In this work, cordierite based dielectric thick films on a Cu plated alumina substrate were investigated in terms of microstructure and property by changing composition of oxide additives, PbO and Cu2O for a given heating schedule. A nonstoichiometric cordierite composition, 2.4MgO 2Al2O3 5SiO2 was used with nucleating agents, B2O3 and P2O5. The dielectric ink consisting of cordierite glass frit and acrylic based binder vehicles was deposited on oxidized Cu layers via screen printing. The thick film layers were fired at 950°C for 30 min in N2 atmosphere. Dissolution of the oxidized Cu into the cordierite layer was observed. The addition of a small amount of Cu2O to the cordierite layer was effective in preventing the dissolution and enhancing thermal expansion. Crystallization was also influenced by the Cu2O addition. A lower activation energy value of 79 kcal/mol for crystallization, calculated from DTA runs, suggested that Cu20 could be used to form the cordierite glass-ceramic at a lower temperature. In the case of no additive, the activation energy for crystallization was 98 kcal/mol. The addition of Cu2O increased dielectric constant. For 3wt% PbO and 1wt% Cu2O, the dielectric constant and loss were determined at 1 MHz as 6.1 and 0.0046, respectively.