Method for manufacturing layered circuit board, layered circuit board, and electronic device

Abstract

There is provided a manufacturing method of a layered circuit board in which a first board and a second board are layered, the manufacturing. The method includes arranging an adhesive resin sheet on the first board so that one face faces the first board, the adhesive resin sheet including a plurality of variant via holes, an opening area on the one face of each of the plurality of variant via holes being larger than an opening area on the other face, filling the variant via holes with conductive paste, arranging the second board on the other face of the adhesive resin sheet after the filling with the conductive paste, and performing heat press treatment to apply pressure to the adhesive resin sheet in a layering direction of the first board and the second board under heat.

What is claimed is: 
     
         1 . A layered circuit board comprising:
 an insulation layer in which insulating resin is cured in a manner to contain a base material;   a first board and a second board of which respective bonding faces are bonded to each other with the insulation layer interposed therebetween; and   a via that is arranged in the insulation layer and electrically connects a first conductor pad that is formed on the bonding face of the first board and a second conductor pad that is formed on the bonding face of the second board; wherein   a portion in which only the insulation resin is cured is formed in part of the insulation layer in a first region in which a conductor area rate is equal to or more than a predetermined reference ratio.   
     
     
         2 . The layered circuit board according to  claim 1 , wherein the portion in which only the insulating resin is cured is formed to be adjacent to a periphery of the via. 
     
     
         3 . An electronic device comprising:
 a layered circuit board; wherein   the layered circuit board includes,   an insulation layer in which insulating resin is cured in a manner to contain a base material;   a first board and a second board of which respective bonding faces are bonded to each other with the insulation layer interposed therebetween; and   a via that is arranged in the insulation layer and electrically connects a first conductor pad that is formed on the bonding face of the first board and a second conductor pad that is formed on the bonding face of the second board; wherein   a portion in which only the insulation resin is cured is formed in part of the insulation layer in a first region in which a conductor area rate is equal to or more than a predetermined reference ratio.