Wiring board

Abstract

A wiring board includes an insulating layer including a first insulating film provided with a first surface and a second surface that is opposite to the first surface, and composed of only resin, and a second insulating film provided with a first surface and a second surface that is opposite to the first surface, including a reinforcing member and resin, in which the reinforcing member is impregnated with the resin, and stacked on the first surface of the first insulating film such that the second surface of the second insulating film contacts the first surface of the first insulating film and the second surface of the first insulating film is exposed outside; and a first wiring layer embedded in the first insulating film, a predetermined surface of the first wiring layer being exposed from the second surface of the first insulating film.

What is claimed is: 
     
         1 . A wiring board comprising:
 an insulating layer including
 a first insulating film provided with a first surface and a second surface that is opposite to the first surface, and composed of only resin, and 
 a second insulating film provided with a first surface and a second surface that is opposite to the first surface, including a reinforcing member and resin, in which the reinforcing member is impregnated with the resin, and stacked on the first surface of the first insulating film such that the second surface of the second insulating film contacts the first surface of the first insulating film and the second surface of the first insulating film is exposed outside; and 
   a first wiring layer embedded in the first insulating film, a predetermined surface of the first wiring layer being exposed from the second surface of the first insulating film.   
     
     
         2 . The wiring board according to  claim 1 ,
 wherein the insulating layer includes an open portion that exposes an opposite surface of the predetermined surface of the first wiring layer, and   wherein the opposite surface of the first wiring layer exposed in the open portion functions as a pad for external connection.   
     
     
         3 . The wiring board according to  claim 2 , wherein a concave portion is formed at a portion of the open portion formed in the first insulating film, the concave portion being formed to expand an inner wall of the open portion in the first insulating film. 
     
     
         4 . The wiring board according to  claim 2 , further comprising:
 a second wiring layer including
 a wiring pattern formed on the first surface of the second insulating film, and 
 a via wiring formed in the open portion and connecting the wiring pattern and the first wiring layer. 
   
     
     
         5 . The wiring board according to  claim 4 ,
 wherein the first insulating film covers a side surface and the opposite surface of the first wiring layer, and   wherein the via wiring is formed to penetrate the second insulating film and the first insulating film to be connected to the opposite surface of the first wiring layer.   
     
     
         6 . The wiring board according to  claim 4 ,
 wherein the first insulating film only covers a side surface of the first wiring layer, and   wherein the via wiring only penetrates the second insulating film to be connected to the opposite surface of the first wiring layer.   
     
     
         7 . The wiring board according to  claim 6 , wherein the opposite surface of the first wiring layer is protruded from the first surface of the first insulating film into the second insulating film. 
     
     
         8 . The wiring board according to  claim 4 , further comprising:
 a second insulating layer stacked on the first surface of the second insulating film of the insulating layer so as to cover the wiring pattern of the second wiring layer; and   a third wiring layer stacked on the second insulating layer to be connected to the wiring pattern of the second wiring layer.   
     
     
         9 . The wiring board according to  claim 1 ,
 wherein the predetermined surface of the first wiring layer exposed from the second surface of the first insulating film composes a plurality of pads, and   the wiring board further comprising:   a solder resist layer stacked on the second surface of the first insulating film and provided with an open portion that exposes the predetermined surface of the first wiring layer composing the plurality of pads.   
     
     
         10 . The wiring board according to  claim 1 , wherein the second surface of the first insulating film is a chip mounting surface on which a semiconductor chip is to be mounted. 
     
     
         11 . The wiring board according to  claim 1 , further comprising:
 a third insulating layer and a fourth wiring layer stacked on the second surface of the first insulating film.   
     
     
         12 . The wiring board according to  claim 1 , wherein the first insulating film includes filler. 
     
     
         13 . The wiring board according to  claim 1 , further comprising:
 a support body provided at the first surface of the second insulating film.   
     
     
         14 . A semiconductor package comprising:
 the wiring board according to  claim 1 ; and   a semiconductor chip mounted on the second surface of the first insulating film.