Wiring substrate having columnar protruding part

Abstract

A method of making a wiring substrate includes forming a first metal layer on a surface of a support member, the first metal layer having at least one columnar through hole that exposes the surface of the support member, forming a columnar metal layer that fills the columnar through hole, forming an insulating layer on the columnar metal layer and on the first metal layer, forming an interconnection layer on a first surface of the insulating layer such that the interconnection layer is electrically connected to the columnar metal layer through the insulating layer, and forming a protruding part including at least part of the columnar metal layer by removing at least the support member and the first metal layer, the protruding part protruding from a second surface of the insulating layer opposite the first surface and serving as at least part of a connection terminal of the wiring substrate.

What is claimed is: 
     
         1 . A wiring substrate, comprising:
 an insulating layer having a first surface and a second surface that is an opposite surface to the first surface, the insulating layer disposed at an outermost layer such that the second surface serves as a surface of the wiring substrate;   an interconnection layer disposed on the first surface of the insulating layer; and   a columnar protruding part protruding from the second surface of the insulating layer,   wherein the columnar protruding part is a connection terminal that has an upper face, a lower face, and side faces, and has a rectangular cross-section taken along a plane parallel to the upper face and the lower face,   wherein the lower face and a part of the side faces meeting the lower face are covered in the insulating layer, and an upper face part of the columnar protruding part protrudes from the second surface of the insulating layer,   wherein the insulator layer has a via hole that exposes the lower face of the columnar protruding part,   wherein the interconnection layer is connected to the lower surface of the columnar protruding part through the via hole,   wherein the columnar protruding part has a structure in which plural metal layers made of different materials are stacked one over another, and   wherein the plural metal layers includes a first-type metal layer having a portion thereof buried in the insulating layer and a remaining portion thereof protruding from the second surface of the insulating layer, and includes a second-type metal layer covering a surface of the remaining portion of the first-type metal layer protruding from the second surface of the insulating layer.   
     
     
         2 . The wiring substrate as claimed in  claim 1 , wherein the second-type metal layer is one of an Au layer, an Ni layer, a layer having an Ni layer and an Au layer stacked from bottom to top in this order, a layer having an Ni layer, a Pd layer, and an Au layer stacked from bottom to top in this order. 
     
     
         3 . The wiring substrate as claimed in  claim 1 , wherein the first-type metal layer is made of Cu. 
     
     
         4 . A semiconductor package, comprising:
 the wiring substrate of  claim 1 ; and   a semiconductor chip having at least one electrode pad,   wherein the protruding part and the electrode pad are electrically connected to each other.   
     
     
         5 . The semiconductor package as claimed in  claim 4 , wherein the protruding part and the electrode pad are connected to each other through a solder layer formed between the protruding part and the electrode pad.