| 摘要 |
PURPOSE:To make the thickness of a film uniform and to improve the corrosion resistance by using an electrolytic tinning bath obtd. by adding a surfactant represented by a prescribed molecular formula to a soln. contg. a free acid component and a bivalent Sn salt when tinning followed by reflow treatment is carried out. CONSTITUTION:A soln. contg. alkanesulfonic acid and/or alkanolsulfonic acid as a free acid component and a bivalent Sn salt is prepd. A surfactant represented by the formula [where (a+c)=2-350 and b=11-66] is added to the soln. to obtain an electrolytic tinning bath. A layer formed by electrolytic tinning in the bath is heated to the m.p. of the layer or above to carry out reflow treatment.
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