Borate glass based ceramic tape

Abstract

A glass composition comprising, based on mole %, 50-67% B.sub.2 O.sub.3 ; 20-50% M.sup.II O where M.sup.II is selected from the group consisting of alkaline earth elements; 2-15% Ln.sub.2 O.sub.3 where Ln is selected from the group consisting of rare earth elements and further comprising, based on mole %, 0-6% M.sup.I.sub.2 O where M.sup.I is selected from the group consisting of alkali elements and 0-10% Al.sub.2 O. The glass composition incorporated into a castable dielectric composition comprising a dispersion of finely divided solids comprising, based on solids: (a) 25-50 wt. % the glass composition; (b) 50-75 wt % refractory oxide; both dispersed in a solution of (c) an organic polymeric binder; and (d) a volatile organic solvent. The castable dielectric composition used in a method of forming a low loss green tape by casting a thin layer of the dispersion onto a flexible substrate and heating the cast layer to remove the volatile organic solvent.

Dependencies are inferred from the claim text.