物理化学学报 >> 2002, Vol. 18 >> Issue (03): 223-227.doi: 10.3866/PKU.WHXB20020307
Gao Su;Zhang Qi-Yun
Abstract: The solderability deterioration of the leads of electronic components often occurs during a longer storage and operation periods in which even more excess of tin layer still remained on the upper part of intermetallics η andε phases formed between the border of Cu and Sn. In this work, hot dipped and electroplated samples with thick tin coating layer more than 120 μm have been investigated by the methods of metallograph, XPS, electrochemical testing and wettability measuring. Some samples have been heat treated at 155 ℃ for 16 h to simulate storage and operation periods. The results indicated that copper rapidly dissolved and diffused deeply into liquid tin phase and also in the solid tin during heat treatment. The dissolved copper accumulated as micro crystals ofηphase suspensing in the tin phase even exposed to the surface of tin coating layer. Close connection of ηSn couples on the tin surface aroused electrochemical corrosion of tin under a moist or acidic atmosphere. The oxidized products deteriorated the solderability of lead wires.
Leads of electronic component,
高苏;张启运. 电子元件覆锡铜引线的腐蚀机制[J]. 物理化学学报, 2002, 18(03): 223-227.
Gao Su;Zhang Qi-Yun. Corrosion Mechanism of Tin Coated Leads of Electronic Component[J]. Acta Phys. -Chim. Sin., 2002, 18(03): 223-227.
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