Design and preparation of BaO–Al2O3–SiO2–B2O3/Quartz LTCC composites with tailored coefficient of thermal expansion

Abstract

In this work, by focusing on widespread problem of thermal mismatch caused by different coefficients of thermal expansion (CTE) in electronic packaging materials, low-temperature co-fired ceramic (LTCC) materials with tunable CTE values were designed. By substituting Ba2+ with Sr2+ and replacing quartz with alumina and zirconia, respectively, BaO–Al2O3–SiO2–B2O3/quartz LTCC composites with CTE of 7.05–9.52 × 10−6/°C were developed. Results show that major crystalline phases of LTCC composite materials are quartz and hexacelsian. By replacing quartz with alumina or zirconia, sintering behavior and subsequently thermal expansion and dielectric properties were modulated. On the other hand, substituting Ba2+ with Sr2+ can be beneficial to the densification of composite materials. The introduction of Sr2+ triggered mixed alkali effect and hindered the crystallization of hexacelsian phase, which can further improve mechanical properties. Finally, sandwich structure module of BaO–Al2O3–SiO2–B2O3/quartz with gradient CTE values was obtained, which showed potential for electronic packaging with sustained thermal compatibility under cyclic temperatures.