A new binderless thick-film piezoelectric paste

This paper presents an investigation into a screen printable piezoelectric paste formulated from a blend of PZT-Pz29 powders of different mean particle size mixed in an organic vehicle. In order to enhance d(33) properties of the thick-film (a piezoelectric coefficient), no binder material was mixed into the paste. The d(33) coefficient and maximum applied electrical field of devices processed at peak temperatures of 150, 200, 750, 850 and 1,000 degrees C were measured and the film adhesion assessed using scratch and tape tests. The applications that would benefit from these enhanced properties are also discussed. The thick-films produced at these processing temperatures showed good adhesion to 96% alumina substrates. They also showed the ability to withstand high electrical fields and a significant enhancement in d(33) when compared to thick-film materials processed at similar temperatures using polymer or glass binders. A maximum average d(33) value of 168pCN(-1) was obtained for samples processed at a peak temperature of 1,000 degrees C. This is 28% higher than the reported d(33) value for a conventional piezoelectric thick-film processed at the same temperature. All samples withstood electric field strengths of over 14 MVm(-1) which is between 2.5 and 4.5 times higher than that used for conventional piezoelectric thick-films.