Composition for producing low sintering temperature ceramic dielectrics and method of manufacturing such dielectrics

Abstract

Powders of BaCO 3 , TiO 2 , ZnO, etc. are mixed to each other at a predetermined ratio of quantity, calcined in an atmospheric air at π°-120° C., and pulverized to obtain a calcined powder having an average grain size from 1 to 3 μ m, 0.1 to 20 parts-by weight of a powder having an average grain size from 0.1 to 1.5 μm comprising a glass having a transition point of not higher than 450° C. obtained by mixing powders of Pb 3 O 4 , SiO 2 , Na 2 O, etc. to each other, melting and then pouring into water and pulverizing the thus obtained glass is admixed to the calcined powder. The mixture is dried, pelleted by adding a resin and the pellet powder is molded into a cylindrical shape, applied with CIP (Cold isotartic press), and the molding product after the treatment is sintered in an atmospheric air at 850° to 1000° C. to obtain a dielectric ceramic sintered at low temperature. The resultant dielectric ceramic has high denseness and high unloaded Q value while maintaining τf within a practical range.

What is claimed is:  
     
       1. A ceramic dielectric prepared by low temperature sintering of a mixture comprising: 
       a calcined powder comprising a BaO.xTiO 2  compound, wherein 3.0≦x≦5.7, from 0.1 to 20 parts by weight of ZnO per 100 parts by weight of the BaO.xTiO 2  compound, from 0.1 to 10 parts by weight of Ta 2 O 5  per 100 parts by weight of the BaO.xTiO 2  compound, and from 0. 1 to 1 parts by weight of MnO 2  per 100 parts by weight of the BaO.xTiO 2  compound; and  
       from 0.1 to 20 parts by weight of a glass powder per 100 parts by weight of the calcined powder, wherein the glass powder has a transition point less than or equal to 450° C.  
     
     
       2. The ceramic dielectric of  claim 1 , wherein the calcined powder further includes at least one of: 
       less than 1 part by weight of WO 3  per 100 parts by weight of the BaO.xTiO 2  compound;  
       not more than 15 parts by weight of SaO 2 per 100 parts by weight of the BaO.xTiO 2  compound;  
       not more than 15 parts by weight of MgO per 100 parts by weight of the BaO.xTiO 2  compound;  
       not more than 10 parts by weight of SrO per 100 parts by weight of the BaO.xTiO 2  compound; and  
       not more than 5 parts by weight of ZrO 2  per 100 parts by weight of the BaO.xTiO 2  compound.  
     
     
       3. The ceramic dielectric of  claim 1  or  2 , wherein the composition has a water absorption of not more than 0.5%, and wherein a product of an unloaded Q value and a resonance frequency of the composition is not less than 2000 GHz as measured using a parallel conductor plate type dielectric resonator method at a measuring frequency of 1-5 GHz. 
     
     
       4. A composition as defined in  claim 3 , wherein the water absorption of the composition is less than 0.1%. 
     
     
       5. A ceramic dielectric of  claim 3 , wherein the product of the unloaded Q value and the resonance frequency of the composition is not less than 3000 GHz. 
     
     
       6. The ceramic dielectric of  claim 4 , wherein the product of the unloaded Q value and the resonance frequency of the composition is not less than 3000 GHz. 
     
     
       7. A method of manufacturing a ceramic dielectric comprising the steps of: 
       calcining a composition at 900° to 1200° C. to provide a calcined product, the composition comprising a BaO.xTiO 2  (3.0≦x≦5.7) compound, from 0.1 to 20 parts by weight of ZnO per 100 parts by weight of the BaO.xTiO 2  compound, from 0.1 to 10 parts by weight of Ta 2 O 5  per 100 parts by weight of the BaO.xTiO 2  compound, and from 0.1 to 1 parts by weight of MaO 2  per 100 parts by weight of the BaO.xTiO 2  compound;  
       pulverizing the calcined product;  
       mixing 1.0 to 20 parts by weight of a glass powder per 100 parts by weight of the pulverized calcined product with the pulverized calcined product, the glass powder having a transition point less than or equal to 450° C.;  
       molding the pulverized calcined product mixed with the glass powder; and  
       sintering the molded pulverized calcined product mixed with the glass powder at 850° to 1000° C.  
     
     
       8. A method of  7 , further comprising the step of blending with the composition at least one of: 
       not more than 1 part by weight of WO 3  per 100 parts by weight of the BaO.xTiO 2  compound;  
       not more than 15 parts by weight of SnO 2  per 100 parts by weight of the BaO.xTiO 2  compound;  
       not more than 15 parts by weight of MgO per 100 parts by weight of the BaO.xTiO 2  compound;  
       not more than 10 parts by weight of SrO per 100 parts by weight of the BaO.xTiO 2  compound; and not more than 5 parts by weight of ZrO 2  per 100 parts by weight of the BaO.xTiO 2  compound.  
     
     
       9. A method of  claim 7  or  8  wherein the glass powder further includes 5 to 60 mol % of PbO per 100 mol % of the glass powder. 
     
     
       10. A method of  claim 7  or  8 , wherein the glass powder further includes 5 to 60 mol % of PbO and 0.01 to 5 mol % of R 2 O per 100 mol % of the glass powder, which R represents an alkali metal. 
     
     
       11. A method of  claim 7  or  8 , wherein an average grain size of the pulverized calcined product is from 1 to 3 μm, and wherein an average grain size of the glass powder is from 0.1 to 1.5 μm and is less than the average grain size of the pulverized calcined product. 
     
     
       12. A method of  claim 9 , wherein an average grain size of the pulverized calcined powder is from 1 to 3 μm, and wherein an average grain size of the glass powder is from 0.1 to 1.5 μm and is less than the average grain size of pulverized calcined product. 
     
     
       13. A method of  claim 10 , wherein an average grain size of the pulverized calcined product is from 1 to 3 μm, and wherein an average grain size of the glass powder is from 0.1 to 1.5 μm and is less than the average grain size of pulverized calcined product. 
     
     
       14. A ceramic dielectric prepared by low temperature sintering of a mixture comprising: 
         a calcined powder including a BaO.xTiO   2    base compound  (   3 . 0 ≦x≦ 5 . 7   ),  ZnO, Ta   2   O   5    and MnO   2   ; and    
       
         a glass powder, wherein the glass powder has a transition point less than or equal to  450 ° C.; and  
       
         wherein the product of an unloaded Q value and a resonance frequency of the dielectric  ( Q×f )  is not less than  2000  GHz as measured using a parallel conductor plate type dielectric resonator method at a measuring frequency of  1 - 5  GHz.   
     
     
       15. The ceramic dielectric of  claim 14 , wherein the product of an unloaded Q value and a resonance frequency of dielectric ( Q×f )  is not less than  3000  GHz.   
     
     
       16. A ceramic dielectric prepared by low temperature sintering of a mixture comprising: 
       
         a calcined powder comprising a BaO.TiO 
         2  
         compound, wherein  3 . 0 ≦x≦ 5 . 7 , from  0 . 1  to  20  parts by weight of ZnO per  100  parts by weight of the BaO.xTiO 
         2  
         compound, from  0 . 1  to  10  parts by weight of Ta 
         2 
         O 
         5  
         per  100  parts by weight of the BaO.xTiO 
         2  
         compound, and from  0 . 1  to  1  parts by weight of MnO 
         2  
         per  100  parts by weight of the BaO.xTiO 
         2  
         compound; and  
       
       
         a glass powder, wherein the glass powder has a transition point less than or equal to  450 ° C. 
       
     
     
       17. A method of manufacturing a ceramic dielectric comprising of steps of: 
         calcining a composition at  900  to  1200 ° C. to provide a calcined product, the composition comprising a BaO.TiO   2  (   3 . 0 ≦x≦ 5 . 7   )  compound, from  0 . 1  to  20  parts by weight of ZnO per  100  parts by weight of the BaO.xTiO   2    compound, from  0 . 1  to  10  parts by weight of Ta   2   O   5    per  100  parts by weight of the BaO.xTiO   2    compound, and from  0 . 1  to  1  parts by weight of MnO   2    per  100  parts by weight of the BaO.xTiO   2    compound;    
       
         pulverizing the calcined product;  
       
       
         mixing a glass powder with the pulverized calcined product, the glass powder having a transition point less than or equal in  450 ° C.;  
       
       
         molding the pulverized calcined product mixed with the glass powder; and  
       
       
         sintering the molded pulverized calcined product mixed with the glass powder at  850  to  1000 ° C.