Sintering and thermomechanical behavior of a Low Temperature Co-fired Ceramic

The thermoelastic, viscoplastic and sintering properties of a commercial Low Temperature Co-fired Ceramic (LTCC, ref. ESL 41111-G) were carefully characterized and correlated to its microstructural features. This LTCC was made of rhombohedral quartz and an amorphous phase composed of silicon, oxygen and some trace amounts of aluminum, carbon and potassium. The dependences of the elastic response vs. temperature and density were characterized by various techniques from nano- to macro-scales. A stable Young's modulus around 54.0 ± 3.5 GPa was measured up to 500 °C before a sharp fall. It was associated with the exceeding of the glass transition temperature (around 576 ± 4 °C). Based on constant heating rate and master sintering curve methodologies, it was shown that the apparent activation energy for free sintering was stable during the whole densification process, with an average value of approximately 291 ± 11 kJ mol−1. The uniaxial viscosity ranged from 0.1 to 2.0 GPa s for relative densities between 0.56 and 0.92. The activation energy identified for viscous flow was similar to the one for free sintering. Moreover, a low and stable value of viscous Poisson's ratio was determined, with an average value around 0.14 ± 0.01 during the initial and intermediate stages of sintering.