Effect of load and thickness on the constrained sintering of LTCC substrates

It is necessary to develop the technique of high integrity ceramic modules with fine patterning, via hole minimizing, and via hole aligning between the layers. The shrinkage of ceramic bodies during sintering reduces the precision of patterns, via-hole alignments, and the large formatting of the substrates. Therefore the importance of shrinkage control of ceramic substrates during sintering is being increased for fabricating high integration modules using the large and flat multilayer ceramic substrates. In this study, the x-y shrinkage of LTCC substrates was controlled to under 0.2% using alumina sacrificial layers by less-pressure assisted sintering. The laminated sheets of alumina/LTCC/alumina were sintered at 900 °C for 30 minutes in air according to a specified sintering profile. Samples with different thicknesses of LTCC sheet and the alumina layer were sintered and the sintering shrinkage of the x-y and z axis were compared with the radius of edge curvature of them. Also the radii of edge curvature of sintered samples were measured as a function of the loads in the range of zero to 1000 g/cm².