真空蒸镀硬脂酸包覆SnAgCu无铅焊料合金粉末研究

Coaty of SnAgCu alloyed powder by Stearic acid via vacuum evaporation

微细无铅焊料合金粉末易团聚和氧化,通过表面改性处理可提高其分散性及抗氧化性。本文以紧耦合气雾化法所制备的SnAgCu合金粉末为原料,采用真空蒸镀法对SnAgCu合金粉末进行包覆硬脂酸的改性研究,研究蒸镀温度、蒸镀时间等工艺条件对SnAgCu合金粉末改性效果的影响;采用扫描电镜(SEM)、透射电镜(TEM)对包覆后合金粉末的形貌及结构进行观测,采用X射线光电子能谱仪(XPS)和碳硫联测仪分别对包覆后粉末的光电子能量和C含量进行测试。研究结果表明:合适的真空蒸镀条件是蒸镀温度70℃,蒸镀时间12h,真空度低于1.6×10-2Pa,在此条件下可得到均匀致密、厚度为5～10nm的包覆层;硬脂酸包覆SnAgCu合金粉末遵循岛状生长机理,其包覆行为是物理吸附过程。

Fine leadless solder alloy powder is easy to be agglomeration and oxidization,whose dispersivity and antioxidation can be improved by surface modification technique. In this paper,the raw material is SnAgCu alloy powder which is produced by the method of close-coupled gas atomization. It was used that vacuum evaporation modify SnAgCu alloy powder by coating stearic acid.The influence of the vacuum evaporation temperature and time on modification effects of SnAgCu alloy powder were studied. Scanning Electricity Microscope （SEM） and transmission electricity microscope （TEM） were used to observe the appearance and structure of coating alloy powder and X-Ray photoelectron spectroscopy（XPS） and carbon-sulfur united testing instrument were adopted to measure photoelectron energy and test C contents of the coating powder. The result indicated that the appropriate conditions of vacuum evaporation were： 70℃ for 12h and lower than 1.6×10-2Pa vacuum degree. In this condition,uniform and compact coating,whose thickness was 5-10nm,could be obtained. The growth mechanism of stearic acid coating SnAgCu alloy powder was following volmer-weber,and the coating behavior was a process of physical adsorption.