Fabrication method of conductive bump structures of circuit board

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.