GLASS CERAMIC AND WIRING BOARD

PROBLEM TO BE SOLVED: To obtain a glass ceramic having high thermal conductivity and low permittivity, and capable of simultaneously firing with low electric resistance metal such as silver, copper, or gold. SOLUTION: The glass ceramic is composed of glass phase at least containing boron (B) and a filler ingredient at least containing aluminum nitride grain, wherein an h-BN phase exists on the boundary between the aluminum nitride grain and the glass phase, or exists as an independent phase of =10 nm thick existing on the boundary between the aluminum nitride grain and the glass phase, and the oxygen in the aluminum nitride grain is