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

Cordierite-based ceramics were developed by sintering a glass selected from MgO-Al{sub 2}O{sub 3}-SiO{sub 2} system with an aim to use the material as high frequency chip inductors. A small amount of B{sub 2}O{sub 3} and P{sub 2}O{sub 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 deg. C having a density of above 99% theoretically, dielectric constant of 5.5, dielectric loss of 0.001 and thermal expansion coefficient of 26.7x10{sup -7} deg. C{sup -1} (20-400 deg. C). Crystalline phases in this sintered sample are predominantly {alpha}-cordierite (hexagonal high cordierite) and trace amount of {mu}-cordierite. SEM depicted a uniformly dense microstructure with crystals of granular habit in the sintered sample.