Based on environmental considerations, global economic pressures, enacted by legislations in several countries, have warranted the elimination of lead from solders used in electronic applications. Sn3.5Ag, SnAgCu, and...Based on environmental considerations, global economic pressures, enacted by legislations in several countries, have warranted the elimination of lead from solders used in electronic applications. Sn3.5Ag, SnAgCu, and Sn0.7Cu have emerged among various lead-free candidates as the most promising solder alloys to be utilized in microelectronic industries. However, with the vast development and miniaturization of modern electronic packaging, new requirements such as superior service capabilities have been posed on lead-free solders. In order to improve the comprehensive property of the solder alloys, two possible approaches were adopted in the current research and new materials developed were patented. One approach was involved with the addition of alloying elements to make new ternary or quaternary solder alloys. Proper addition of rare earth element such as La and Ce have rendered solder alloys with improved mechanical properties, especially creep rupture lives of their joints. Another approach, the composite approach, was developed mainly to improve the service temperature capability of the solder alloys. Composite solders fabricated by mechanically incorporating various reinforcement particles to the solder paste have again exhibited enhanced properties without altering the existing processing characteristics. The recent progress and research efforts carried out on lead-free solder materials in Beijing University of Technology were reported. The effects of rare earth addition on the microstructure, processing properties, and mechanical properties were presented. The behaviors of various Sn-3.5Ag based composite solders were also explicated in terms of the roles of reinforcement particles on intermetallic growth, steady-state creep rate, the onset of tertiary creep, as well as the overall creep deformation in the solder joints. Thermomechanical fatigue (TMF) behavior of the solder alloys and composite solders were investigated with different parameters such as ramp rate, dwell time, etc. The damage accumulation f展开更多
无卤素水基助焊剂普遍存在表面张力大,活性差,残留多以及易发霉等难题,文章通过对活性剂、助溶剂、缓蚀剂以及表面活性剂等组分的优化较好地解决了这些问题,研制了一种无卤素水基免清洗助焊剂NC902。经检测,该助焊剂的各项性能均达到国...无卤素水基助焊剂普遍存在表面张力大,活性差,残留多以及易发霉等难题,文章通过对活性剂、助溶剂、缓蚀剂以及表面活性剂等组分的优化较好地解决了这些问题,研制了一种无卤素水基免清洗助焊剂NC902。经检测,该助焊剂的各项性能均达到国家相关助焊剂标准要求。助焊剂对无铅焊料Sn0.7Cu的平均铺展率达到80.75%。采用SAT-5100可焊性测试仪测试了该焊剂的润湿性能,结果显示零交时间为0.90秒,润湿时间为1.35秒,最大润湿力为3.47 m N,平均润湿角为25.60°。展开更多
基金This work was financially supported by the National863High-Tech.Project,Ministry of Science andTechnology,Ministry of Education,Beijing Science&Technology Commission(No.2004B03)and Beijing Educational Commission.
文摘Based on environmental considerations, global economic pressures, enacted by legislations in several countries, have warranted the elimination of lead from solders used in electronic applications. Sn3.5Ag, SnAgCu, and Sn0.7Cu have emerged among various lead-free candidates as the most promising solder alloys to be utilized in microelectronic industries. However, with the vast development and miniaturization of modern electronic packaging, new requirements such as superior service capabilities have been posed on lead-free solders. In order to improve the comprehensive property of the solder alloys, two possible approaches were adopted in the current research and new materials developed were patented. One approach was involved with the addition of alloying elements to make new ternary or quaternary solder alloys. Proper addition of rare earth element such as La and Ce have rendered solder alloys with improved mechanical properties, especially creep rupture lives of their joints. Another approach, the composite approach, was developed mainly to improve the service temperature capability of the solder alloys. Composite solders fabricated by mechanically incorporating various reinforcement particles to the solder paste have again exhibited enhanced properties without altering the existing processing characteristics. The recent progress and research efforts carried out on lead-free solder materials in Beijing University of Technology were reported. The effects of rare earth addition on the microstructure, processing properties, and mechanical properties were presented. The behaviors of various Sn-3.5Ag based composite solders were also explicated in terms of the roles of reinforcement particles on intermetallic growth, steady-state creep rate, the onset of tertiary creep, as well as the overall creep deformation in the solder joints. Thermomechanical fatigue (TMF) behavior of the solder alloys and composite solders were investigated with different parameters such as ramp rate, dwell time, etc. The damage accumulation f
文摘无卤素水基助焊剂普遍存在表面张力大,活性差,残留多以及易发霉等难题,文章通过对活性剂、助溶剂、缓蚀剂以及表面活性剂等组分的优化较好地解决了这些问题,研制了一种无卤素水基免清洗助焊剂NC902。经检测,该助焊剂的各项性能均达到国家相关助焊剂标准要求。助焊剂对无铅焊料Sn0.7Cu的平均铺展率达到80.75%。采用SAT-5100可焊性测试仪测试了该焊剂的润湿性能,结果显示零交时间为0.90秒,润湿时间为1.35秒,最大润湿力为3.47 m N,平均润湿角为25.60°。
