Connection structure for a substrate and a method of fabricating the connection structure

Abstract

A connection structure for a substrate is provided. The substrate has a plurality of connection pads and an insulation protection layer with the connection pads being exposed therefrom. The connection structure includes a metallic layer formed on an exposed surface of each of the connection pads and extending to the insulation protection layer, and a plurality of conductive bumps disposed on the metallic layer and spaced apart from one another at a distance less than or equal to 80 μm, each of conductive bumps having a width less than a width of each of the connection pads. Since the metallic layer covers the exposed surfaces of the connection pads completely, a colloid material will not flow to a surface of the connection pads during a subsequent underfilling process of a flip-chip process. Therefore, the colloid material will not be peeled off from the connection pads.

What is claimed is: 
     
         1 . A connection structure for a substrate, the substrate having a plurality of connection pads and an insulation protection layer with the connection pads being exposed therefrom, the connection structure comprising:
 a metallic layer formed on the connection pads exposed from the insulation protection layer and extending to the insulation protection layer; and   a plurality of conductive bumps disposed on the metallic layer and spaced apart from one another at a distance less than or equal to 80 μm, each of conductive bumps having a width less than a width of each of the connection pads.   
     
     
         2 . The connection structure of  claim 1 , wherein the metallic layer comprises titanium, copper or nickel. 
     
     
         3 . The connection structure of  claim 1 , wherein the conductive bumps are copper pillars. 
     
     
         4 . A method of fabricating a connection structure for a substrate, comprising:
 providing a substrate having a plurality of connection pads and an insulation protection layer formed thereon wherein the connection pads are exposed from the insulation protection layer;   forming on the insulation protection layer a first resist layer having a plurality of first openings for the connection pads and a portion of the insulation protection layer to be exposed therefrom;   forming a metallic structure in the first openings and on the first resist layer;   removing the metallic structure on the first resist layer, allowing the metallic structure to be disposed in the first openings only and act as a metallic layer, the metallic layer being thus formed on exposed surfaces of the connection pads and extending to the insulation protection layer;   removing the first resist layer; and   forming a plurality of conductive bumps on the metallic layer, each of the conductive bumps having a width less than a width of the exposed surface of each of the connection pads.   
     
     
         5 . The method of  claim 4 , wherein the first resist layer is made of aluminum, copper, or nickel/vanadium. 
     
     
         6 . The method of  claim 4 , wherein the first openings of the first resist layer are formed by etching. 
     
     
         7 . The method of  claim 4 , wherein the metallic layer is made of titanium, copper or nickel. 
     
     
         8 . The method of  claim 4 , wherein the conductive bumps are copper pillars. 
     
     
         9 . The method of  claim 4 , wherein any two of the conductive bumps are spaced apart from a distance less than or equal to 80 μm. 
     
     
         10 . The method of  claim 4 , wherein the conductive bumps are fabricated by:
 forming a second resist layer on the insulation protection layer and the metallic layer, and forming on the second resist layer a plurality of second openings for a portion of the metallic layer to be exposed therefrom;   forming the conductive bumps in the second openings; and   removing the second resist layer.   
     
     
         11 . The method of  claim 10 , wherein each of the second openings has a radius size less than a projection area of the exposed surface of each of the connection pads.