Negative thermal expansion ScF₃ ceramic for electronic packaging applications

To meet the demands of miniaturization and integration in modern electronic packaging, developing materials with low coefficient of thermal expansion (CTE) is essential to reduce thermal stress and enhance device reliability. In this study, the dense negative thermal expansion ceramic ScF₃ was prepared with a CTE of −8.86 × 10⁻⁶/℃. The ScF₃ ceramic was cold sintered at 150 ℃, exhibiting a low permittivity of 5.3 and a high quality factor (Q×f) of 14,700 GHz. By incorporating ScF₃ to the hexagonal boron nitride (BN) ceramic, the CTE of ScF₃—BN composite ceramic was adjusted to 3.36 × 10⁻⁶/℃, establishing compatibility with silicon-based chips. And finite element simulations verified that ScF₃—BN composite significantly reduces thermal stress compared to Li₂MoO₄ or Al₂O₃ ceramics. Furthermore, this work demonstrates the potential of cold-sintered ScF₃ to regulate thermal expansion in packaging substrates, paving the way for improved performance in next-generation electronic devices.