Sintering and crystallization of cordierite glass ceramics for high frequency multilayer chip inductors

摘要

Cordierite-based ceramics were developed by sintering a glass selected from MgO-Al_2O_3-SiO_2 system with an aim to use the material as high frequency chip inductors. A small amount of B_2O_3 and P_2O_5 were added to optimize the preparation conditions. The glass powder and sintered bodies were characterized by different analytical techniques such as TG-DTA analysis, X-ray diffraction, transmission and scanning electron microscopy. Pellets uniaxially pressed from the glass power could be sintered well at 950℃ having a density of above 99% theoretically, dielectric constant of 5.5, dielectric loss of 0.001 and thermal expansion coefficient of 26.7 x 10~(-7)℃~(-1) (20-400℃). Crystalline phases in this sintered sample are predominantly μ-cordierite (hexagonal high cordierite) and trace amount of α-cordierite. SEM depicted a uniformly dense microstructure with crystals of granular habit in the sintered sample.