Characterization of Borosilicate Glass‐Coated Cu Electrode for Internal Electrode of Multilayer Ceramic Device

In this study, a process was proposed, which allows a base metal electrode to be burnt‐out in an oxidative atmosphere for fabrication of multilayer ceramic device. To protect Cu in an oxidative atmosphere, the Cu powder was coated with borosilicate glass via a sol–gel process. The oxidation resistance and shrinkage of the glass‐coated Cu were investigated. When a 10% glass‐coated Cu was heated up to 500°C under an oxidative atmosphere, the Cu could survive without the formation of copper oxide. The oxidation of the Cu was observed when heating at temperatures above 700°C. This might be due to exposure of Cu to oxidative atmosphere related to the softening behavior of glass. The glass‐coated Cu exhibited a shrinkage behavior, which follows the shrinkage behavior of glass in the low temperature range and the shrinkage of pure Cu in the high temperature range. To measure the electrical conductivity of the glass‐coated Cu electrode, the Cu pastes were prepared and printed onto an alumina substrate. The binder burn‐out process of the glass‐coated Cu was carried out at 550°C under an air atmosphere, and was then sintered at 1000°C under a nitrogen atmosphere. The electrical conductivity of the Cu electrode measured was above 10 ⁴ Ω cm, which means that it can be used as the internal electrode of a multilayer device.