Lead free ltcc tape composition

Abstract

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.