Successful Lead-Free Implementation: Pre-Conditions and Status
Based on experimental analysis of different solder materials for conventional SMD devices and BGA / LFBGA components the quality of Pb-free interconnections will be discussed followed by any reliability results. Solder materials demonstrate evolving microstmcture and mechanical behavior that changes significantly with environmental exposures such as thermal cycling and high temperature storage. The damage mechanism for lead-free solder joints on different board finishes at elevated operating conditions is not sufficient understood in terms of the dependency of fatigue properties and IMC formation from all material and process parameter. Further demands from portable electronics are the drop test characterizing interface performance of different package constructions in relation to decreased pad constructions / solder volumes and therefore interface. The ratio of the pad diameter to the solder volume is one of the key parameter influencing the concentration gradients and therefore the metallurgical interaction. The paper discusses the characterization of interfaces based on SnAgCu and SnAgCuXYZ solder pastes and ball materials, the stability after accelerated tests and the description of modified interfaces strictly related to the assembly conditions, dissolution behavior of finishes on component and board side and the influence of intermetallic formation. The types of intermetallic as well as the quantity of intermetallics are observed, primarily the constitution, hardness, E modules describing the ability of strain/stress compensation. Results of board level reliability are presented after TCT and HTS. Solder materials, finishes at interposer and pcb influencing damage mechanisms at interfaces, the progress using optimized interconnection materials is demonstrated. In this paper, environmentally benign component materials in combination with lead free solders were discussed related to the ability of interaction to different surface finishes on package and board side, investigated for compatibility with existing or modified process parameters and to describe the board level reliability compared to conventional solder materials. The material selection is done based on demands to implement lead-free solders successful (Lead-free, low melting, high fatigue resistant for extended applications under the operating point of view).
Lead-free soldering solders qualification demands and solutions
Albrecht, Hans-Jürgen
Siemens AG, Corporate Technology CT MM 6, Siemensdamm 50, D-13623 Berlin
国际会议
Chinas Premier SMT & MPT Event(2007年中国国际表面贴装和微组装技术大会)
上海
英文
1-12
2007-03-22（万方平台首次上网日期，不代表论文的发表时间）