Solder ball pad surface finish structure of circuit board and fabrication method thereof

摘要

A solder ball pad surface finish structure of a circuit board and a method for fabricating the same are proposed. An insulative protecting layer with a plurality of openings is formed on a circuit board to expose solder ball pads on the circuit board. A conductive layer is formed on the insulative protecting layer and in the openings, and a resist layer is also formed thereon. A plurality of openings are formed and defined in the resist layer corresponding to the solder ball pads. The area of openings of resist layer can be larger or smaller than the area of the openings of insulative protecting layer, and the resist layer is hung above the solder ball pads. A metal layer is formed on the conductive layer and in the openings of resist layer by electroplating and an adhesive layer is formed successively. Then, the resist layer and the conductive layer underneath the resist layer are removed. Afterwards, the adhesive layer is further processed by re-flow process.