US Patent 7776649 Method for fabricating wafer level chip scale packages

A method for fabricating a plurality of wafer level chip scale packages is revealed. A bumped wafer is laminated with a mold plate with a protection film placed thereon to partially embed the bumps of the wafer into the protection film and to form an underfill gap between the wafer and the protection film. By a first sawing step, the wafer fixed by the protection film is singulated into a plurality of chips having sides between the active surface and the back surface and also a filling gap is formed between the sides. Then, an encapsulant is formed on the protection film where the encapsulant fills the underfill gap through the filling gap to completely encapsulate the chips and the non-embedded portions of the bumps. By separating the encapsulant from the protection film and a second sawing step, the mold plate and the protection film are removed, and the encapsulant is singulated into a plurality of individual wafer level chip scale packages.