To eliminate Pb from a soldering material and avoid the public pollution due to effluence of Pb being wasted by applying an alloy plating to connection terminals of a BGA or CSP at a specified m.p., using an Sn-based alloy of one metal selected from among In, Zn, Bi and Ag at a specified content to Sn.

In a ball lead IC package type, an LSI chip of IC chip is molded on a printed wiring board, ball leads of a plating material except for Pb, are provided on an electrode pattern on the lower surface of the wiring board and bonded and fixed to an electrode pattern of a printed wiring board to be a base facing them wherein the alloy plating material is an Sn-In alloy contg. In 3-5%, Sn-Zn alloy contg. Zn 10-20%, Sn-Bi alloy contg. Bi 5-10%, or Sn-Ag alloy contg. Ag 3.5%, and any of them is used for plating at a m.p. of around 220°C. This eliminates Pb from the solder material and prevents the occurrence of pollution due to Pb effluence during waste discharging.