Wiring board and method of fabricating the same

Abstract

A wiring board includes an electrode pad having a first surface and a second surface located on an opposite side from the first surface, a conductor pattern connected to the first surface of the electrode pad, and an insulator layer embedded with the electrode pad and the conductor pattern. The insulator layer covers an outer peripheral portion of the second surface of the electrode pad.

1 . A wiring board comprising:
 an electrode pad having a first surface and a second surface located on an opposite side from the first surface;   a conductor pattern connected to the first surface of the electrode pad; and   an insulator layer embedded with the electrode pad and the conductor pattern,   wherein the insulator layer covers an outer peripheral portion of the second surface of the electrode pad.   
     
     
         2 . The wiring board as claimed in  claim 1 , wherein:
 the insulator layer has an opening exposing a portion of the second surface; and   the opening has a shape that widens from the electrode pad in towards a direction away from the electrode pad.   
     
     
         3 . The wiring board as claimed in  claim 1 , wherein:
 the electrode pad includes a first metal layer exposed at the opening and made of a metal different from a metal forming the conductor pattern, a second metal layer provided on the first metal layer and made of a metal different from the metal forming the conductor pattern, and a third metal layer provided on the second metal layer and made of the metal forming the conductor pattern; and   the third metal layer connects to the conductor pattern.   
     
     
         4 . The wiring board as claimed in  claim 3 , wherein outer peripheral side surfaces of the second metal layer are disposed on an inner side compared to outer peripheral side surfaces of each of the first metal layer and the third metal layer. 
     
     
         5 . The wiring board as claimed in  claim 1 , wherein the electrode pad is made of a metal forming the conductor pattern, and further comprising:
 an Organic Solderbility Preservative (OSP) layer covering the second surface of the electrode pad at a portion exposed at the opening.   
     
     
         6 . A method of fabricating a wiring board, comprising:
 an electrode pad forming step forming an electrode pad on a support plate made of a first metal;   a projecting part forming step forming, on the support plate at a portion opposing the electrode pad, a projecting part which exposes a surface of the electrode pad on a side opposing the support plate and contacts the electrode pad, by etching the support plate;   an insulator layer forming step forming an insulator layer covering the electrode pad, the projecting part, and a surface of the support plate formed with the projecting part;   a conductor pattern forming step forming, on the insulator layer, a conductor pattern connected to the electrode pad; and   a support plate removing step removing the support plate formed with the projecting part by an etching, after the conductor pattern forming step, to thereby expose a portion of the surface of the electrode pad on the side opposing the support plate and form in the insulator layer an opening having a shape corresponding to a shape of the projecting part.   
     
     
         7 . The method of fabricating the wiring board as claimed in  claim 6 , wherein the projecting part forming step etches the support plate so that the shape of the projecting part widens from the electrode pad towards the support plate. 
     
     
         8 . The method of fabricating the wiring board as claimed in  claim 6 , wherein:
 the electrode pad forming step includes:
 a first metal layer forming step forming a first metal layer made of a metal different from the first metal; and 
 a second metal layer forming step forming, on the first metal layer, a second metal layer made of a metal different from the first metal, 
   wherein the projecting part forming step etches the support plate using the electrode pad as a mask and using an etchant which selectively etches the first metal.   
     
     
         9 . The method of fabricating the wiring board as claimed in  claim 8 , wherein:
 the electrode pad forming step further includes:
 a third metal layer forming step forming, on a surface of the second metal layer, a third metal layer made of the first metal, after the second metal layer forming step, 
   wherein the third metal layer forming step forms the third metal layer to a thickness sufficient to cover the surface of the second metal layer after the projecting part forming step is carried out.   
     
     
         10 . The method of fabricating the wiring board as claimed in  claim 8 , wherein:
 the electrode pad forming step further includes:
 a third metal layer forming step forming, on a surface of the second metal layer, a third metal layer made of the first metal, after the second metal layer forming step; and 
 a protection layer forming step forming, on the third metal layer, a protection layer which prevents etching of the third metal layer when the support plate is etched in the projecting part forming step, 
   and further comprising:   a protection layer removing step removing the protection layer, between the projecting part forming step and the insulator layer forming step.   
     
     
         11 . The method of fabricating the wiring board as claimed in  claim 6 , further comprising:
 a height adjusting layer forming step forming a height adjusting layer made of the first metal on a portion of the support plate corresponding to a region where the electrode pad is formed, prior to the electrode pad forming step,   wherein the support plate removing step removes the height adjusting layer together with the support plate using the etchant which selectively etches the first metal.   
     
     
         12 . A method of fabricating a wiring board, comprising:
 a metal layer forming step forming a metal layer on a support plate made of a first metal;   an electrode pad forming step forming an electrode pad on the metal layer;   a projecting part forming step forming a projecting part by etching the metal layer, and exposing an outer peripheral portion of a surface of the electrode pad in contact with the projecting part;   an insulator layer forming step forming an insulator layer to cover the projecting part, the electrode pad, and a surface of the support plate formed with the projecting part, after the projecting part forming step;   a conductor pattern forming step forming, on the insulator layer, a conductor pattern connected to the electrode pad;   a support plate removing step removing the support plate by an etching, after the conductor pattern forming step; and   a projecting part removing step removing the projecting part, after the conductor pattern forming step, to thereby expose a portion of the surface of the electrode pad in contact with the projecting part and form in the insulator layer an opening having a shape corresponding to a shape of the projecting part.   
     
     
         13 . The method of fabricating the wiring board as claimed in  claim 12 , wherein the metal layer is made of a material having an electrical conductivity different from that of the first metal. 
     
     
         14 . The method of fabricating the wiring board as claimed in  claim 12 , wherein the electrode pad is made of the first metal. 
     
     
         15 . The method of fabricating the wiring board as claimed in  claim 12 , wherein the electrode pad forming step includes successively stacking, on the metal layer, a first metal layer made of a metal different from the first metal, a second metal layer made of a metal different from the first metal, and a third metal layer made of the first metal, to thereby form the electrode pad. 
     
     
         16 . The method of fabricating the wiring board as claimed in  claim 15 , wherein the electrode pad forming step forms the second metal layer using a metal forming the metal layer. 
     
     
         17 . The method of fabricating the wiring board as claimed in  claim 12 , further comprising:
 a step forming an Organic Solderbility Preservative (OSP) layer on a portion of the electrode pad exposed from the insulator layer by carrying out an Organic Solderbility Preservative (OSP) process.