Fabrication method of conductive bump structures of circuit board

Abstract

A fabrication method of conductive bump structures of a circuit board includes providing the circuit board with a plurality of electrically connecting pads formed on at least one surface thereof and covering the circuit board with an insulating protection layer formed a plurality of openings to expose the electrically connecting pads; forming a conductive layer on surfaces of the insulating protection layer and openings, and forming a metal layer on the conductive layer by electroplating, with the openings of the insulating protection layer being deposited by the metal layer; forming a resist layer on the metal layer wherein the resist layer is further patterned to form a plurality of openings corresponding to the electrically connecting pads to partially expose the metal layer; forming an adhesive layer in the openings of the resist layer; and removing the resist layer, and then removing the metal layer and conductive layer not covered by the adhesive layer, to form conductive bump structures on the electrically connecting pads.

1 . A fabrication method of conductive bump structures of a circuit board, comprising the steps of: 
 providing the circuit board with a plurality of electrically connecting pads formed on at least one surface thereof, and applying an insulating protection layer on the circuit board, the insulating protection layer having a plurality of openings to expose the electrically connecting pads;    forming a conductive layer on surfaces of the insulating protection layer and openings thereof, and forming a metal layer on the conductive layer by electroplating, with the openings of the insulating protection layer being deposited by the metal layer;    forming a resist layer on the metal layer, wherein the resist layer is further patterned to form a plurality of openings corresponding to the electrically connecting pads to partially expose the metal layer;    forming an adhesive layer in the openings of the resist layer; and    removing the resist layer, and then removing the metal layer and conductive layer that are not covered by the adhesive layer, such that portions of the metal layer and conductive layer underneath the adhesive layer corresponding to the electrically connecting pads are retained to form the conductive bump structures on the electrically connecting pads.    
   
   
       2 . The fabrication method of  claim 1 , wherein the electrically connecting pads are fabricated by steps comprising: 
 forming a conductive layer on an insulating surface layer of the circuit board;    forming a resist layer on the conductive layer on the insulating surface layer and forming a plurality of openings on the resist layer to partially expose the conductive layer on the insulating surface layer; and    forming the electrically connecting pads in the openings of the resist layer by electroplating.    
   
   
       3 . The fabrication method of  claim 2 , further comprising removing the resist layer and the conductive layer underneath the resist layer.  
   
   
       4 . The fabrication method of  claim 1 , wherein the adhesive layer is formed on the metal layer by one of an electroplating process and a printing process.  
   
   
       5 . The fabrication method of  claim 1 , wherein the adhesive layer is made of a material selected from the group consisting of tin (Sn), silver (Ag), gold (Au), copper (Cu), nickel (Ni), lead (Pb), platinum (Pt) and an alloy thereof.  
   
   
       6 . The fabrication method of  claim 5 , wherein the adhesive layer is reflowed to completely cover an exposed surface of the metal layer partially exposed via the openings of the resist layer.  
   
   
       7 . The fabrication method of  claim 1 , wherein the metal layer is made of a material selected from the group consisting of Pb, Sn, Ag, Cu and an alloy thereof.  
   
   
       8 . The fabrication method of  claim 1 , wherein the conductive layer is made of a metal material.  
   
   
       9 . The fabrication method of  claim 1 , wherein the conductive layer is made of an organic polymer material.  
   
   
       10 . A fabrication method of conductive bump structures of a circuit board, comprising the steps of: 
 providing the circuit board with a plurality of electrically connecting pads formed on at least one surface thereof, and applying an insulating protection layer on the circuit board, the insulating protection layer having a plurality of openings to expose the electrically connecting pads;    forming a conductive layer on surfaces of the insulating protection layer and openings thereof, and forming a metal layer on the conductive layer by electroplating, with the openings of the insulating protection layer being deposited by the metal layer;    applying a resist layer on the metal layer and patterning the resist layer such that the resist layer only covers the metal layer corresponding to the electrically connecting pads;    removing the metal layer and the conductive layer that are not covered by the resist layer; and    removing the resist layer and forming an adhesive layer on an exposed surface of the metal layer by electroless plating.    
   
   
       11 . The fabrication method of  claim 10 , wherein the electrically connecting pads are fabricated by steps comprising: 
 forming a conductive layer on an insulating surface layer of the circuit board;    forming a resist layer on the conductive layer on the insulating surface layer and forming a plurality of openings on the resist layer to partially expose the conductive layer on the insulating surface layer; and    forming the electrically connecting pads in the openings of the resist layer by electroplating.    
   
   
       12 . The fabrication method of  claim 11 , further comprising removing the resist layer and the conductive layer underneath the resist layer.  
   
   
       13 . The fabrication method of  claim 10 , wherein the adhesive layer is made of a material selected from the group consisting of Sn, Ag, Au, Cu, Ni, Pb, Pt and an alloy thereof.  
   
   
       14 . The fabrication method of  claim 10 , wherein the metal layer is made of a material selected from the group consisting of Pb, Sn, Ag, Cu and an alloy thereof.  
   
   
       15 . The fabrication method of  claim 10 , wherein the conductive layer is made of a metal material.  
   
   
       16 . The fabrication method of  claim 10 , wherein the conductive layer is made of an organic polymer material.