改性松香对SnAg3.0Cu0.5焊锡膏性能的影响

通过改性松香对铜板腐蚀性实验,确定、优选出腐蚀性较小的两种改性松香,研究了改性松香及其复配对焊锡膏扩展率及粘度的影响,测试了焊锡膏的锡珠、坍塌、润湿性等性能。结果表明:不同类型的改性松香对铜板腐蚀、扩展率、粘度等均匀有较大的影响,适当的改性松香复配可有效提高焊接性,调配锡膏粘度。

Influence of bismuth on microstructure,thermal properties,mechanical performance,and interfacial behavior of SAC305−xBiCu solder joints

This research sought to improve the properties of SAC305 solder joints by the addition of 1 and 2 wt.%Bi.The effects of bismuth doping on the microstructure,thermal properties,and mechanical performance of the SAC305−xBiCu solder joints were investigated.Bi-doping modified the microstructure of the solder joints by refining the primaryβ-Sn and eutectic phases.Bi-doping below 2 wt.%dissolved in theβ-Sn matrix and formed a solid solution,whereas Bi additions equal to or greater than 2 wt.%formed Bi precipitates in theβ-Sn matrix.Solid solution strengthening and precipitation strengthening mechanisms in theβ-Sn matrix increased the ultimate tensile strength and microhardness of the alloy from 35.7 MPa and 12.6 HV to 55.3 MPa and 20.8 HV,respectively,but elongation decreased from 24.6%to 16.1%.The fracture surface of a solder joint containing 2 wt.%Bi was typical of a brittle failure rather than a ductile failure.The interfacial layer of all solder joints comprised two parallel IMC layers:a layer of Cu6Sn5 and a layer of Cu3Sn.The interfacial layer was thinner and the shear strength was greater in SAC305−xBiCu joints than in SAC305Cu solder joints.Therefore,small addition of Bi refined microstructure,reduced melting temperature and improved the mechanical performance of SAC305Cu solder joints.

一种BGA焊锡球表面处理剂及其性能评价

目前国内还鲜见针对芯片封装用焊锡球表面处理剂方面的研究报道。为此,以SnAg3.0Cu0.5合金焊料的球珊阵列封闭(BGA)焊锡球为基础,研制并评价了一种BGA焊锡球表面处理剂。该表面处理剂是由85%~92%(质量分数,下同)的松香、5%~10%的聚乙烯、2%~4%的低熔点蜡以及0.5%~1.0%的活性剂和增塑剂等添加剂组成,再将其按质量份数将1份混合液用80份正己烷稀释而制成。通过对覆膜后BGA锡球的焊接过程、微观组织、空洞情况、黏球情况、抗氧化性以及在焊锡球表面的包裹状态等为评价指标,评价了该表面处理剂的性能。结果表明:此种表面处理剂的使用能够满足焊锡球的焊点饱满且均匀、焊接性能良好、不黏球、抗氧化膜包覆均匀且抗氧化性能优异等必要条件,能够满足公司内控及BGA焊锡球的客户使用要求。