High-temperature solders having a higher melting point than solder alloys used for soldering of printed circuit boards are used for internal bonding of electronic parts, but high-temperature solders which are free from Pb have not been developed. There exist high-temperature solders which comprises Sn balls and Cu balls and which perform bonding through the formation of an intermetallic compound without melting to form a single-phase structure, but they have poor wettability to the lands of a printed circuit board or electrodes of electronic parts and have not been used.A solder paste according to the present invention is provided by mixing flux with a powder mixture of Sn powder or an Sn based lead-free solder powder with Cu or Ag powder which has Ni plating formed on its surface. Although the solder paste performs bonding by means of an intermetallic compound without melting to form a single phase structure, the Ni plating acts as a barrier which retards the formation of the intermetallic compound so as to leave enough time to permit wetting of the lands of a printed circuit board or electrodes of an electronic part.