| 摘要 |
PROBLEM TO BE SOLVED: To provide a tinned steel sheet which has excellent wettability in Pb-free soldering, corrosion resistance and whisker properties without using Pb and Cr which are considered as environmentally undesirable substances. SOLUTION: The surface of a steel sheet is provided with a tinning layer having a coating weight of 5.0 to 20.0g/m<SP>2</SP>whose covering ratio exceeds 99% via an Fe-Sn alloy layer formed by tin melting treatment. The upper layer of the tinning layer is provided with a chemical conversion film comprising P and Si. The coating weights of P and Si in the chemical conversion film are controlled to the ranges of 0.5 to 10 mg/m<SP>2</SP>and 30 to 150 mg/m<SP>2</SP>, respectively. COPYRIGHT: (C)2004,JPO
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