Wettability of electrode metals on barium titanate substrate

The wettability and bonding strength between electrode metals and dielectrics are very important for internal electrodes, terminations, and soldering of multilayer ceramic passive components. In this work, the contact angles of electrode metals, including Pb, Sn, Au, Ag, Ag/Pd, and Cu on BaTiO3 were measured. Results showed that the addition of Pd into Ag significantly reduced the contact angle of Ag on BaTiO3 substrate. The wettability of noble metals (Ag and Au) is nearly independent of the partial pressure of oxygen, under the circumstances of the investigated oxygen partial pressure and within the accuracy of the contact angle measurement. However, molten Cu changes its contact angle drastically when using purified Ar (102 degrees) instead of as-received Ar (89 degrees), and in an air atmosphere (64 degrees). The work of adhesion, according to Young-Dupre equation, was also calculated for these metals. Results were compared with those on ZrO2, SiO2 and Al2O3. (C) 2001 Kluwer Academic Publishers.