Development of Micro-structured Sn-2Ag-0.1Al Solder with Highly THermal Fatigue Durability

Addition of small amount of Al suppressed super cooling of Sn-Ag solders completely under normal cooling rates and the Sn-2Ag-0.1Al solder has a fine structure with an average grain sizes less than 10 micron-meter. Stress-strain measurements showed that the Sn-2Ag-0.1Al solder have fracture strain and toughness superior than the conventional Sn-Ag solders and wetting of the Sn-2Ag-0.1Al solder was moderate. Thermal cycling test was carried for the Cu / ceramic module with a 200 micro meter Sn-2Ag-0.1Al solder sheet between 233 and 398K. Dor comparison purpose conventional solders as Sn-3Ag-0.5Cu were also tested under the same thermal cycling condition. It was found that the Sn-2Ag-0.1Al solder was still sound after the 300 T.C. in contrast to results for Sn-3Ag-0.5Cu failed completely after the 150 T.C.. The crack formed in the module with a Sn-2Ag-0.1Al solder propagated within the solder, but it was passed through the solder / Cu substrate interface for the module with a Sn-3Ag-0.5Cu. Micro-structuring process of the solder with Al addition could be discussed.Proceedings of "Electronics Goes Green 2004+ : Driving Forces for Future Electronics"http://egg2004.izm.fraunhofer.de

Evaluating the Variability of Sea-surface Wind Stress by the Combined of Eddy Correlation and Inertial Dissipation Methods

Field measurements of wind stress over the ocean surface were made at a sea observation tower by the combined use of the eddy correlation and inertial dissipation methods, which are referred to as \u22ECM\u22 and “IDM” hereafter, respectively. The values of the wind stresses obtained from both methods should agree well under ideal surface layer conditions. Thus, confirming the degrees of agreement between the stresses from ECM and IDM make it possible to reveal how air-sea momentum transfer varies depending on wave-field conditions. The present data show the degrees of agreement to depend significantly on the wave age in the case of pure windsea. This means that imbalance factors in the turbulent kinetic energy equation become large with increasing the wave age. Also, the degrees of agreement between ECM and IDM are found to vary with the deflection of the wind stress vector from the wind direction, which are caused by the presence of swell