Conductive bump structure of circuit board and method for fabricating the same

Abstract

A conductive bump structure of a circuit board and a method for fabricating the same are proposed. The circuit board with a plurality of electrical connection pads is provided. An insulating protective layer and a resist layer are successively applied on the circuit board, wherein openings are formed in the layers at positions corresponding to the pads to expose the pads. Then, a conductive layer is formed on surfaces of the resist layer and openings, and a metal layer is formed on the conductive layer via electroplating and filled in the openings. Subsequently, the metal layer and conductive layer formed on the resist layer are removed via thinning, so as to form metal bumps on the pads. After the resist layer is removed, the metal bumps are covered by an adhesive layer to form a conductive bump structure for electrically connecting the circuit board to the external electronic component.

1 . A method for fabricating a conductive bump structure of a circuit board, comprising the steps of: 
 providing the circuit board having at least a surface formed with a plurality of electrical connection pads;    forming an insulating protective layer and a resist layer on the circuit board in sequence;    forming a plurality of openings in the insulating protective layer and resist layer at positions corresponding to the electrical connection pads to expose the electrical connection pads of the circuit board;    forming a conductive layer on surfaces of the resist layer and openings;    forming a metal layer on the conductive layer via electroplating, and filling the metal layer in the openings of the insulating protective layer and the resist layer;    removing the metal layer and conductive layer formed on the surface of the resist layer via thinning, and retaining the metal layer and conductive layer filled in the openings to form metal bumps on the electrical connection pads; and    removing the resist layer, and forming an adhesive layer over exposed surfaces of the metal bumps, so as to form the conductive bump structure for electrically connecting the circuit board to the external electronic component.    
   
   
       2 . The method for fabricating a conductive bump structure of a circuit board of  claim 1 , wherein the method for fabricating the electrical connection pads comprises steps of: 
 forming a conductive layer on an insulating layer formed on a surface of the circuit board;    forming a resist layer on the conductive layer, and forming openings of the resist layer to expose a portion of the conductive layer; and    forming the electrical connection pads in the openings of the resist layer via electroplating.    
   
   
       3 . The method for fabricating a conductive bump structure of a circuit board of  claim 2 , further comprising the step of removing the resist layer and the conductive layer covered by the resist layer.  
   
   
       4 . The method for fabricating a conductive bump structure of a circuit board of  claim 1 , wherein the openings of the insulating protective layer and resist layer are formed via one of plasma etching and laser drilling.  
   
   
       5 . The method for fabricating a conductive bump structure of a circuit board of  claim 1 , wherein the metal bumps are made of the metal layer and the conductive layer formed at positions corresponding to the electrical connection pads.  
   
   
       6 . The method for fabricating a conductive bump structure of a circuit board of  claim 1 , wherein the adhesive layer is an organic solderability preservative.  
   
   
       7 . The method for fabricating a conductive bump structure of a circuit board of  claim 1 , wherein the adhesive layer is made of a material selected from the group consisting of copper (Cu), tin (Sn), lead (Pb), silver (Ag), nickel (Ni), gold (Au), platinum (Pt) and their alloys.  
   
   
       8 . The method for fabricating a conductive bump structure of a circuit board of  claim 1 , wherein the metal layer is made of a material selected from the group consisting of copper (Cu), tin (Sn), lead (Pb), silver (Ag), and their alloys.  
   
   
       9 . The method for fabricating a conductive bump structure of a circuit board of  claim 1 , wherein the thinning process is one of etching or abrading.  
   
   
       10 . The method for fabricating a conductive bump structure of a circuit board of  claim 1 , wherein the resist layer is removed via one of chemical stripping and physical tearing.  
   
   
       11 . A method for fabricating a conductive bump structure of a circuit board, comprising the steps of: 
 providing the circuit board having at least a surface formed with a plurality of electrical connection pads;    forming an insulating protective layer on the circuit board in sequence, and forming a plurality of openings in the insulating protective layer to expose the electrical connection pads of the circuit board;    forming a resist layer on the insulating protective layer, and forming a plurality of openings in the resist layer at positions corresponding to the openings of the insulating protective layer to expose the electrical connection pads;    forming a conductive layer on exposed surfaces of the resist layer and openings;    forming a metal layer on the conductive layer via electroplating, and filling the metal layer in the openings;    removing the resist layer, the conductive layer and metal layer formed on the surface of the resist layer to form metal bumps on the electrical connection pads of the circuit board, wherein the metal bumps comprise the metal layer and conductive layer; and    forming an adhesive layer over exposed surfaces of the metal bumps.    
   
   
       12 . The method for fabricating a conductive bump structure of a circuit board of  claim 11 , wherein the method for fabricating the electrical connection pads comprises steps of: 
 forming a conductive layer on an insulating layer formed on a surface of the circuit board;    forming a resist layer on the conductive layer, and forming openings of the resist layer to expose a portion of the conductive layer; and    forming the electrical connection pads in the openings of the resist layer via electroplating.    
   
   
       13 . The method for fabricating a conductive bump structure of a circuit board of  claim 12 , further comprising the step of removing the resist layer and the conductive layer covered by the resist layer.  
   
   
       14 . The method for fabricating a conductive bump structure of a circuit board of  claim 11 , wherein the process of removing the resist layer and conductive layer covered by the resist layer is to remove the metal layer and conductive layer formed on the surface of the resist layer first via thinning and retain the metal layer and conductive layer filled in the openings.  
   
   
       15 . The method for fabricating a conductive bump structure of a circuit board of  claim 11 , wherein the process of removing the resist layer and conductive layer covered by the resist layer is to remove the resist layer, the metal layer and conductive layer formed on the surface of the resist layer first via physical methods.  
   
   
       16 . The method for fabricating a conductive bump structure of a circuit board of  claim 11 , wherein the adhesive layer is made of a material selected from the group consisting of copper (Cu), tin (Sn), lead (Pb), silver (Ag), nickel (Ni), gold (Au), platinum (Pt) and their alloys.  
   
   
       17 . The method for fabricating a conductive bump structure of a circuit board of  claim 11 , wherein the adhesive layer is an organic solderability preservative.  
   
   
       18 . The method for fabricating a conductive bump structure of a circuit board of  claim 11 , wherein the metal layer is made of a material selected from the group consisting of copper (Cu), tin (Sn), lead (Pb), silver (Ag), and their alloys.  
   
   
       19 . The method for fabricating a conductive bump structure of a circuit board of  claim 11 , wherein the openings of the insulating protective layer and the resist layer are formed by patterning process such as exposure and developing or by laser.  
   
   
       20 . A conductive bump structure of a circuit board, wherein a surface of the circuit board is formed with an electrical connection pad and covered by an insulating protective layer, an opening is formed in the insulating protective layer to expose the electrical connection pad covered by the insulating protective layer and the conductive bump structure is formed on the electrical connection pad of the circuit board and protruded from the opening of the insulating protective layer, the conductive bump structure comprising: 
 a metal bump having a metal layer and a conductive layer formed on the lateral and bottom sides of the metal layer, wherein the metal bump is protruded from the opening of the insulating layer; and    an adhesive layer covering the exposed surface of the metal bump.    
   
   
       21 . The conductive bump structure of a circuit board of  claim 20 , wherein the adhesive layer is made of a material selected from the group consisting of copper (Cu), tin (Sn), lead (Pb), silver (Ag), nickel (Ni), gold (Au), platinum (Pt) and their alloys.  
   
   
       22 . The conductive bump structure of a circuit board of  claim 20 , wherein the adhesive layer is an organic solderability preservative.