PROBLEM TO BE SOLVED: To provide a method of forming a dam for damming a molten solder on a printed wiring board, in which a conductor such as a land of which shape and position are accurate is easily and surely formed on a printed wiring board, and a solder bridge is hard to occur.;SOLUTION: Dams D1 and D2 for damming molten solder consisting of mounds a and c whose height is about 2 μm and a recess b of about 2 μm are formed at the gold plating on the surface of a printed wiring board C under laser beam irradiation. The surface of gold plating of regions a, b, and c has such property as repelling of the molten solder. When solder pastes B1 and B2 are applied in the area surrounded with the dams D1 and D2 and then heated, solders B1' and B2' having been melted by heating are repelled from the dams D1 and D2. The heights of the solders B1' and B2' can be higher than the dams D1 and D2. The molten solders B1' and B2' are caused to return to a normal temperature in the dams D1 and D2, to prepare a land. The dams D1 and D2 can be manufactured with accurate shape, size, height, and position.;COPYRIGHT: (C)2012,JPO&INPIT
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