| abstract |
There is provided a bump process suitable for manufacturing bumps on a wafer. The bump process is to form a patterned solder mask on the wafer and multiple openings of the solder mask respectively expose the pads on the wafer, in which the cross section area of two ends of these openings is smaller than the cross section area of its center. Next, solder is filled into these openings. After reflow process, the solder in the openings becomes spherical bumps. Finally, the solder mask is removed. In addition, the bump process can also first pre-form solder blocks on the pads of the wafer. Then, a patterned solder mask is formed on the wafer and solder is filled in the openings of the exposed pads of the solder mask. After reflow process, the pre-formed solder blocks and the solder are melted to form bumps, in which the compositions of the pre-formed solder block and solder can be different. |