Dielectric material with low temperature coefficient and high unloaded quality, process for producing the same, and single/multilayer circuit board containing the same

摘要

A dielectric material is disclosed which has a small absolute value of the temperature coefficient of resonance frequency and a high coefficient of unloaded quality. Also disclosed are a process for producing the dielectric material and multilayer and other circuit boards containing the dielectric material. The dielectric material is a highly densified material having a water absorption lower than 0.1%, which is obtained by mixing 95.5 to 99.5 percent by weight mixture of a glass frit and a strontium compound with 0.5 to 4.5 percent by weight titanium dioxide, compacting the resultant mixture, and sintering the compact at a relatively low temperature around 930°C. This dielectric material is a glass ceramic containing strontium anorthite (SrAl2Si2O8) as the main crystalline phase, and may contain the TiO2, which remains unchanged after sintering. The absolute value of the temperature coefficient of resonance frequency of the dielectric material is 20 ppm/°C or lower, preferably 10 ppm/°C or lower, more preferably 5 ppm/°C or lower. The product of the unloaded quality coefficient and resonance frequency is 1,800 GHz or larger, preferably 2,500 GHz or larger. This material therefore has excellent dielectric properties.