Densified ceramic green sheet and stack having conductors therein

摘要

When a dispersion of oxide ceramic particles in certain volatile organic solvents is mixed with less than about 2 percent by weight (based on the weight of particles) of an oligomeric polysiloxanol dispersant, and the dispersion allowed to settle, the oligomer provides a multiplicity of OH groups, many of which are available for interactive bonding to the surfaces of the particles. The net result is that the particles settle more slowly; also, the sediment has a density higher than that of sediment from a dispersion of the same particles in the same solvent mixed with the monomeric silane from which the oligomer was formed. Exceptionally dense and strong "tape", for making sintered circuitized multilayered ceramic structures, is produced by capitalizing on this phenomenon. The effectiveness of the oligomer is predicated upon the prehydrolysis of the siloxane, prior to forming the dispersion. In a stable suspension with the binder, the slip viscosity is lowered compared to that of a slip containing no dispersant, or the siloxane monomer as dispersant, at dynamic shear rates in the range of 5-70 sec-1. Green cards cut from the tape have greater pull strength, higher Young's modulus, higher stress at break, higher adhesion to each other in a stack, and higher strain at break than green cards made from a slip containing no polysiloxanol oligomer.