A method for mounting a semiconductor device, which can decrease the occurrence rate of failures, a method for repairing a semiconductor device, which can easily repair defective solder joints, and a semiconductor device which makes those methods feasible. A substrate 1 has formed therein through-holes 7 lined on the internal walls with a wiring layer 9, and solder balls 6 are fusion-bonded to the substrate 1 in such a manner as to cover the through-holes 7. In the mounting process or in the repair process, heating probes 41 are passed through the through-holes 7 and thrust into the solder balls 6 to thereby melt the solder balls, and the heating probes are pulled out of the solder balls to let the solder balls cool down. In those processes, only the solder balls 6 can be heated, thereby averting adverse effects on the IC chip 3. In the repair process, the solder balls 6 can be restored to an initial condition free of intermetallic compounds.