PURPOSE: To provide a method of forming a bump adequate for COG-mounting a semiconductor chip on a circuit board.

CONSTITUTION: A bump C is composed of a bump main body 4 of In, In-Ag alloy, or Pb-Sn alloy electrodeposited on a conductor circuit 2 or a semiconductor chip of a circuit board at a prescribed position and a bump sheath 5 of Cu, Au, Pd, Ag, Ni, or Pd-Ni alloy which covers the top or all the surface of the main body 4. Therefore, even if the formed bumps 4 are somewhat irregular in height, when the semiconductor chip 7 is mounted thereon and thermocompressed as a whole, as In, In-Ag alloy, or Pb-Sn alloy is low-melting material, the bumps 4 are softened at a temperature where a thermocompression process is carried out to be uniform in height. At this point, the bump sheath 5 envelops the bump main body 4 preventing the main body 4 from flowing out to an adjacent conductor circuit to cause a short circuit between the conductor circuits. A bump of this design can be useful for a liquid panel of high precision.