| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of a solder ball after reflow by composing a cream solder of solder powder and flux and constituting the solder powder with resin balls in which a nickel plated film and an alloy plated film of a specified melting point or lower are successively formed on a surface thereof and which has a specified particle size or smaller. SOLUTION: A solder powder is a resin ball on which a nickel plated film and an alloy plated film of <=250 deg.C melting point are successively formed on a surface and which has a particle size of <=10μm. The alloy of <=250 deg.C melting point used in this case is preferably Sn-Pb, Sn-Pb-Ag, Sn-Ag, Sn-Ag-Bi, Sn-Pb-Bi, In-Bi, etc. A resin material for a resin ball may be either a thermoplastic resin or a thermosetting resin. The solder powder is made so that after a nickel plated film 3 is formed on a resin ball 2 of 5μm diameter, a plated film 4 of an eutectic solder of Sn.Pb is formed thereon.
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