Calcium Zinc Borosilicate Glass with High Thermal Expansion Coefficient for LTCC Applications

Composition of calcium zinc borosilicate glass has been designed from the viewpoint of achieving high thermal expansion for low temperature co‐firing ceramic applications. Coefficient of thermal expansion (CTE) of the glass increased with the total percentage of CaO plus ZnO up to 70 mol%, and it also increased with CaO/ZnO ratio up to 50/20 under the constraint of 70 mol% of total CaO plus MgO, beyond which glass forming was impossible. All the CTE behaviors were qualitatively well correlated by the prediction of Hormadaly's model and the simple rule of mixture based on Appen's constant, while the former was shown to be a better tool on a quantitative base for the design of glass composition. Dielectric constant of the developed glass was generally within the range predicted by the Appen's constant. The designed glass, 50CaO·20ZnO·20B2O3·10SiO2, demonstrated CTE of 12.8 × 10−6/K and dielectric constant of 13.5. ?>