Effect of Ca–Al–Si–O common glass on dielectric properties of low-temperature co-fired ceramic materials with different fillers

High-density integration in single component used for mobile communication is highly demanded with the miniaturization trend in multi-functional light-weighted mobile communication devices. Embedding passive components into multi-layered ceramic chips is also increasingly needed for high integrity. The need for high strength materials to be used in handheld devices has also increased. To this end, many attempts to join different low-temperature co-fired ceramics (LTCC) materials with different dielectric constants have been made, but failed with de-laminations or internal cracks mainly due to difference of thermal expansion coefficients. It is thought that this difference could be minimized with the use of common glass in different LTCC materials. In this study, several candidates of common glass were mixed with various fillers of LTCC to have various dielectric constants in the radio-frequency, and to minimize the mismatch in joining. Ca-Al-Si-O glass was mixed with 1.3MgO-TiO2, cordierite and CaTiO3. Mixtures were tape-cast and sintered to be compared with their micro-structures, dielectric properties and thermo-mechanical characteristics. When 1.3MgO-TiO2 with volumetric ratio of 30% was mixed with Ca-Al-Si-O glass, the measured dielectric constant was 7.9, the quality factor was 3708. With 45 volumetric percent of cordierite, the dielectric constant was 5 and the quality factor was 1052.