- 著者
- Flora Somidin Stuart David McDonald Xiaozhou Ye Dongdong Qu Keith Sweatman Tetsuya Akaiwa Tetsuro Nishimura Kazuhiro Nogita
- 出版者
- The Japan Institute of Electronics Packaging
- 雑誌
- Transactions of The Japan Institute of Electronics Packaging (ISSN:18833365)
- 巻号頁・発行日
- vol.13, pp.E19-004-1-E19-004-11, 2020 (Released:2020-05-27)
- 参考文献数
- 29
- 被引用文献数
- 4
The polymorphic transformation that occurs in the Cu6Sn5 intermetallic compound (IMC) at 186°C has the potential to generate stresses that could lead to cracking of that phase in soldered joints during the multiple reflow cycles of a typical printed board assembly process and the thermal cycles to which electronic assemblies are exposed during service. In this paper the authors report on the effect of variations in the cooling stage of a reflow soldering thermal profile on the incidence and extent of cracking in the Cu6Sn5 at the interface between solder alloys and copper substrates. The solder alloy/substrate combinations studied were Sn-3.0Ag-0.5Cu/Cu and Sn-0.7Cu-0.05Ni-1.5Bi/Cu. The cooling conditions were (i) the direct-cooling of a conventional reflow profile, and (ii) an alternative reflow profile with one of three extended isothermal holding periods of 30, 60, and 180 seconds at 140°C during the cooling stage. It was found that the alternative reflow profiles reduced cracking in the interfacial Cu6Sn5 IMC layer and this resulted in improved resistance of the reflowed solder ball to failure in high speed impact shear when the distribution of stress tends to favor crack propagation though the interfacial IMC rather than through the bulk solder.
- 著者
- Kazuhiro Nogita Stuart D. McDonald Arne K. Dahle
- 出版者
- The Japan Institute of Metals and Materials
- 雑誌
- MATERIALS TRANSACTIONS (ISSN:13459678)
- 巻号頁・発行日
- vol.45, no.2, pp.323-326, 2004 (Released:2005-06-24)
- 参考文献数
- 13
- 被引用文献数
- 115 171
The effects of different concentrations of individual additions of rare earth metals (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) on eutectic modification in Al-10 mass%Si has been studied by thermal analysis and optical microscopy. According to the twin-plane reentrant edge (TPRE) and impurity induced twinning mechanism, rare earth metals with atomic radii of about 1.65 times larger than that of silicon, are possible candidates for eutectic modification. All of the rare earth elements caused a depression of the eutectic growth temperature, but only Eu modified the eutectic silicon to a fibrous morphology. At best, the remaining elements resulted in only a small degree of refinement of the plate-like silicon. The samples were also quenched during the eutectic arrest to examine the eutectic solidification modes. Many of the rare-earth additions significantly altered the eutectic solidification mode from that of the unmodified alloy. It is concluded that the impurity induced twinning model of modification, based on atomic radius alone, is inadequate and other mechanisms are essential for the modification process. Furthermore, modification and the eutectic nucleation and growth modes are controlled independently of each other.
- 著者
- Kazuhiro Nogita Mathew C. Greaves Benjamin D. Guymer Bernard B. Walsh James M. Kennedy Michael D. Duke Tetsuro Nishimura
- 出版者
- The Japan Institute of Electronics Packaging
- 雑誌
- Transactions of The Japan Institute of Electronics Packaging (ISSN:18833365)
- 巻号頁・発行日
- vol.3, no.1, pp.104-109, 2010 (Released:2011-04-21)
- 参考文献数
- 10
- 被引用文献数
- 3 5
The authors produced a demonstration electric vehicle, "Deep Green Research," based on a Honda Civic, in which critical electrical connections were soldered with a lead-free Sn–Cu–Ni–Ge alloy. This paper reports on the team's participation and completion in the Global Green Challenge, the world's largest solar car and eco car race, from Darwin to Adelaide, Australia that was run in late October, 2009. The successful completion of this course under the harsh conditions of the Australian outback proved the high reliability of the Sn–Cu–Ni–Ge lead-free solder joints in the control panels, cables, and connectors that had to carry the heavy current required to propel the vehicle over long distances at speeds of up to 104 km/hour. The vehicle set a new record for the longest distance travelled on a single charge by a car that satisfies relevant Australian safety regulations. This distance of 360 km was achieved using lithium-ion batteries with a total capacity of 33 kWh and resulted in an award in the category "Modified Production Class — Small Car (Electric)".