Creating Single‐Crystalline β‐CaSiO₃ for High‐Performance Dielectric Packaging Substrate

Abstract

Abstractβ‐CaSiO3 based glass‐ceramics are among the most reliable materials for electronic packaging. However, developing a CaSiO3 glass‐ceramic substrate with both high strength (>230 MPa) and low dielectric constant (<5) remains challenging due to its polycrystalline nature. The present work has succeeded in synthesizing single‐crystalline β‐CaSiO3 for a high‐performance glass‐ceramic substrate. This is accomplished by introducing Al3+ into the CaO‐B2O3‐SiO2 glass system, and by optimizing the sintering condition. Al3+ doping facilitates a heterogeneous network structure that energetically favors the precipitation of polycrystalline particles, including nanosized β‐CaSiO3 crystals and sub‐nanosized α‐CaSiO3 crystals. As the sintering temperature increases, the nano α‐CaSiO3 crystals (2–10 nm) are gradually absorbed by the β‐CaSiO3 crystals. Through atomic rearrangement, α‐CaSiO3 crystals transform into micrometer‐sized single crystal β‐CaSiO3 (1–2 µm) with layered structure. The low temperature co‐fired β‐CaSiO3 glass‐ceramics exhibit exceptional properties, including a low dielectric constant of 4.04, a low dielectric loss of 3.15 × 10−3 at 15 GHz, and a high flexural strength of 256 MPa. This work provides a new strategy for fabricating high‐performance single‐crystalline glass‐ceramics for electronic packaging and other applications.