制备不同Zn含量的Sn—Zn系合金粉末,分别在室温和120℃下进行合金氧化实验,用质量增加测量法考察合金氧化动力学行为,用XRD检测氧化产物的物相,并测量向熔融松香中加入不同量的ZnO时体系的黏度随时间的变化。结果表明:固态Sn—Zn合金的氧化产物为SnO2和ZnO,并呈现致密氧化膜的特征;Sn-Zn合金的氧化速率随着Zn含量的增加而加快。过量的ZnO可使松香发生稠化。根据以上结果提出,在钎焊过程中ZnO导致的使松香助焊剂局部稠化失效以及包覆熔体表面的ZnO膜的机械阻碍作用是Sn-Zn系无铅焊料润湿性差的主要原因。
Powders of Sn-Zn alloys with different Zn contents were prepared. Oxidation behaviors of the powders at room temperature and at 120℃ were investigated by means of weight-gaining and XRD. The results show that SnO2 and ZnO with characteristic of dense oxide films are formed during oxidation of Sn-Zn alloys, and that oxidation of Sn-Zn alloys is accelerated with increasing Zn content. Furthermore, ZnO can thicken the rosin. It is proposed that the mechanical impediment to the spreading of the molten alloy, resulted from the cladding effect of ZnO, and the local thickening of rosin based flux by ZnO, result in the poor wettability of Sn-Zn lead-solders.