极化时间与电位对铅锡合金钝化层性能的影响

Effects of polarization time and potential on performance of lead/tin passivation layer

锡能改变钝化层的电子导电性 ,通过在不同电位和各种极化时间下电化学阻抗的测量来研究电子导电性与钝化层形成条件的关系。在 70 0mV的极化区域内 ,钝化层的电阻随极化时间的增加而增加 ,但加入合金锡以后 ,极化电阻减小 ,这主要是由于锡的加入促进了半导体的PbO与锡氧化物的形成。当电位进入到 15 0 0mV时 ,形成了PbOx,由于PbOx 的导电性好于PbO ,所以钝化层的阻抗较小 ,但随着极化时间的增加 ,阻抗还是逐渐增加 ,这主要是PbOx 在 70 0mV处又还原成PbO。

Tin could change electronic conductivity of the passivation layer. The relationship between the electronic conductivity and the formation condition of the passivation layer was studied by measuring the electrochemical impedance at different polarization potential and polarization time. When the lead electrode was pola- rized in the region of 700 mV, the polarization resistance increased with time but decreased when tin was alloyed. This can be explained by the increasing formation of semi-conducting PbO and conducting tin oxide. With a potential incursion in the region of 1500 mV, PbO x was formed. Due to the better conductivity of PbO x than PbO, the passivation layer had lower impedance. However, the resistance increased with polarization time. This can be interpreted by the reduction of PbO x to PbO at 700 mV.