LEAD FREE LTCC TAPE COMPOSITION
A glass composition consisting essentially of, based on mole percent, 46-56% B 2 O 3 , 0.5-8.5% P 2 O 5 , SiO 2 and mixtures thereof, 20-50% CaO, 2-15% Ln 2 O 3 where Ln is selected from the group consisting of rare earth elements and mixtures thereof; 0-6% M′ 2 O where M′ is selected from the group consisting of alkali elements; and 0-10% Al 2 O 3 , with the proviso that the composition is water millable.
1 - 15 . (canceled)
16 . A glass composition comprising, based on mole percent, 0.5-8.5% of a glass former selected from the group consisting of P 2 O 5 , SiO 2 and mixtures thereof; 46-57.96% B 2 O 3 , 20-50% CaO, 2-15% Ln 2 O 3 where Ln is selected from the group consisting of rare earth elements and mixtures thereof; 0-6% M′ 2 O where M′ is selected from the group consisting of alkali elements; and 0-10% Al 2 O 3 , with the proviso that the composition is water millable.
17 . The composition of claim 16 wherein Ln 2 O 3 is La 2 O 3 .
18 . The composition of claim 16 wherein M′ 2 O is selected from the group consisting of Li 2 O, Na 2 O and mixtures thereof.
19 . The composition comprising, based on solids:
(a) 25-100 weight % glass composition of claim 16 ;
(b) 0-75 weight % refractory oxide; both dispersed in a solution of
(c) organic polymeric binder.
20 . The composition of claim 19 further comprising a volatile organic solvent.
21 . The composition of claim 19 further comprising 0-5 weight % Cu 2 O.
22 . The composition of claim 19 wherein the refractory oxide is selected from the group consisting of Al 2 O 3 , α-quartz, CaZrO 3 , mullite, cordierite, fosterite, zircon, zirconia, BaTiO 3 , CaTiO 3 , MgTiO 3 , amorphous silica and mixtures thereof.
23 . The composition of claim 19 wherein the refractory oxide is Al 2 O 3 .
24 . The composition of claim 16 wherein the CaO is partially substituted by BaO, MgO or mixtures thereof.
25 . A green tape formed by casting a layer of the dielectric composition of claim 20 onto a flexible substrate forming a cast layer, and heating the cast layer to remove the volatile organic solvent forming a solvent-free layer.
26 . The tape of claim 25 wherein the solvent-free layer is separated from the substrate.
27 . The tape of claim 25 wherein a conductor composition is deposited on the tape.
28 . An article comprising the tape of claim 27 wherein the tape is processed to volatilize the organic polymeric binder and sinter the glass composition.