Multi-component LTCC substrate with a core of high dielectric constant ceramic material and processes for the development thereof

Abstract

The present invention is directed to a method to produce a co-fired, metallized high dielectric constant ceramic core comprising: providing a precursor green laminate comprising at least one layer of core tape wherein said core tape has a dielectric constant of at least 20; and firing said precursor green laminate. The method is further directed to a method to produce a low-temperature co-fired ceramic structure comprising: providing a precursor green laminate comprising at least one layer of core tape wherein said tape has a dielectric constant of at least 20; firing said precursor green laminate during a first firing to form a high dielectric constant ceramic core; providing one or more layers of metallized low dielectric constant primary tape; laminating one or more layers of said metallized low dielectric constant primary tape to said core; and firing said core and primary tape layers during a second firing.

1 - 2 . (canceled)  
   
   
       3 . A method to produce a low temperature co-fired ceramic structure comprising: 
 providing a precursor green laminate comprising at least one layer of metallized, core tape, wherein said tape has a dielectric constant of at least 20;    firing said precursor green laminate during a first firing to form a high dielectric constant ceramic core;    providing one or more layers of metallized low dielectric constant primary tape;    laminating one or more layers of said metallized low dielectric constant primary tape to said core; and    firing said core and primary tape layers during a second firing;    optionally providing at least one self constraining tape layer wherein the at least one self-constraining tape layer is applied to the top or bottom of said green laminate and cofired with said green laminate such that said core does not shrink in the x- and y- directions during said first firing;    wherein the green laminate comprises internal or embedded capacitors providing values of from 10 pico-farads to 100 nano-farads,    wherein said structure does not shrink in the x- and y- direction during said second firing; and    wherein overall shrinkage of said structure shrinks less than 0.3% and the reproducibility of the overall shrinkage is less than 0.04%.    
   
   
       4 . The method of  claim 3  wherein the green laminate comprises two to ten layers of said core tape.  
   
   
       5 - 8 . (canceled)  
   
   
       9 . The method of  claim 3  wherein said high dielectric constant core comprises, in weight percent, materials selected from mixtures of lead iron tungstate niobate solid solutions 30-80%, calcined mixtures of barium titanate, lead oxide and fused silica 20-70%, barium titanate 30 to 50%, calcined mixtures of barium titanate 30 to 50%, barium titanate and calcined mixtures of barium titanate 30 to 50%, lead oxide and fused silica 50-80%, and a lead germanate glass 3-20%.  
   
   
       10 . The method of  claim 3  wherein said high dielectric constant core tape comprises, in weight percent, a solid solution of lead iron niobate and lead iron tungstate 40%, a calcined mixture of BaTiO 3 , PbO, and fused SiO 2  40%, and an organic medium 20%.  
   
   
       11 . The method of  claim 3 , wherein the high dielectric constant core tape comprises, in weight percent, BaTiO3 66%, lead germanate glass 4%, and an organic medium 30% and wherein said lead germanate glass comprises, in weight percent, 78.5% Pb3O4 and 21.5% GeO2.  
   
   
       12 . The method of  claim 3 , wherein the high dielectric constant core tape comprises, in weight percent, a calcined mixture of BaTiO 3 , Pb3O4, and BaO70%, a lead germanate glass 10%, and an organic medium 20%.  
   
   
       13 . A low temperature cofired ceramic structure formed by the method of claims  3 .  
   
   
       14 . A functioning circuit comprising the low temperature cofired ceramic structure of  claim 13.