Multilayer ceramic substrate and its production method

Abstract

An object of the invention is to connect different dielectrics electrically to each other in the direction of main surface of a sheet in a multilayer ceramic substrate and to increase the degree of flexibility in design and make the multilayer ceramic substrate compact in size. A multilayer ceramic substrate in accordance with the invention is formed of a plurality of laminated ceramic substrates including such a composite ceramic substrate of different materials that is made by inserting the second ceramic substrate in a pounched-out portion made in the first ceramic substrate and by planarizing its top and bottom surfaces, wherein a conductive layer is formed in a portion across a boundary between the first ceramic substrate and the second ceramic substrate of the interface of the composite ceramic substrate of different materials.

1 . A multilayer ceramic substrate comprising a plurality of laminated ceramic substrates including a composite ceramic substrate of different materials that is made by inserting a second ceramic substrate in a punched-out portion made in a first ceramic substrate and by planarizing its top and bottom surfaces, wherein a conductive layer is formed in a portion across a boundary between the first ceramic substrate and the second ceramic substrate of an interface of the composite ceramic substrate of different materials.  
   
   
       2 . The multilayer ceramic substrate according to  claim 1 , wherein the composite ceramic substrates of different materials are overlaid on each other above and below in a direction of lamination, and the second ceramic substrates are also overlaid on each other and have an internal conductive layer interposed therebetween.  
   
   
       3 . The multilayer ceramic substrate according to  claim 1 , wherein any one or both of the first ceramic substrate and the second ceramic substrate has or have a via hole.  
   
   
       4 . The multilayer ceramic substrate according to  claim 1 , wherein the first ceramic substrate and the second ceramic substrate are formed of materials of different dielectric constants.  
   
   
       5 . The multilayer ceramic substrate according to  claim 1 , wherein the ceramic substrate is a substrate fired at a low temperature (LTCC substrate).