Hybrid package, glass ceramic substrate for the hybrid package, and composition for the glass ceramic substrate

A hybrid package comprising a glass ceramic substrate layer and an aluminum nitride substrate bonded to said glass ceramic substrate layer by a bonding portion;

• said glass ceramic substrate layer, said aluminum nitride substrate and said bonding portion each having a respective thermal expansion coefficient, said glass ceramic substrate layer and said aluminum nitride substrate having a difference in thermal expansion coefficient having an absolute value of not more than 20.times.10.sup.-7 .degree. C., said aluminum nitride substrate and said bonding portion having a difference in thermal expansion coefficient having an absolute value of not more than 30.times.10.sup.-7 /.degree. C.;
• said glass ceramic substrate layer being made of at least one glass ceramic substrate comprising inorganic components consisting essentially of from 50 to 91% by weight of alumina, from 5 to 30% by weight of SiO.sub.2, from 3 to 20% by weight of PbO, from 0 to 15% by weight of B.sub.2 O.sub.3, from 0.5 to 15% by weight of an alkaline earth metal oxide and from 0 to 6% by weight of oxides of Ti+Zr+HF, and from 0.05 to 10% by weight, based on the total amount of the inorganic components, of chromium oxide+vanadium oxide+cerium oxide+cobalt oxide+tin oxide where the chromium oxide is calculated as Cr.sub.2 O.sub.3, the vanadium oxide is calculated as V.sub.2 O.sub.5, the cerium oxide is calculated as CeO.sub.2, the cobalt oxide is calculated as CoO and the tin oxide is calculated as SnO.sub.2.