Paper 11.3

EXPERIMENTAL WETTABILITY STUDIES COMBINED WITH THE RELATED PROPERTIES FROM DATA BASES FOR LEAD-FREE SOLDERING MATERIALS

Moser Z.¹, Gąsior W.¹, Ishida K.², Ohnuma I.², Bukat K.³, Pstrus J.¹, Sitek J. ³ and  Kisiel R.⁴.

¹Polish Academy of Sciences, Institute of Metallurgy and Materials Science, 30-

059Kraków, Reymonta Str.25, POLAND

²Department of Materials Science, Graduate School of Engineering, Tohoku  

           University, Aoba-yama 02, Sendai 980-8579, JAPAN

³Tele and Radio Research Institute, 03-450 Warszawa, Ratuszowa Str.11, POLAND

⁴Institute of Microelectronics and Optoelectronics, Warsaw University of 

            Technology, 00-662 Warszawa, Koszykowa Str.75,POLAND

One of the tendencies in modeling of Pb-free soldering materials are the investigations of quaternary and quinary systems on the base of  Sn-Ag or  Sn-Ag-Cu eutectics with Bi and Sb additions. Main aim is to obtain alloys with wettability and T_m closer to 183⁰ C characteristic for traditional Sn-Pb eutectic soldering materials. In this study we intend to use data base for Pb-free solders developed in Tohoku University in Japan, to calculate the quaternary phase diagram Sn-Ag-Cu-Bi by means of CALPHAD method and the melting phenomena, to simulate solidification using Scheil model and to calculate surface tensions from thermodynamic parameters of the liquid phase by the Butler’s model.

The resulting calculated surface tensions will be verified with experimental data from maximum bubble pressure method (performed within 250^o C to temperatures exceeding 900⁰C) and with interfacial tensions from meniscographic studies made at 250⁰ C using various fluxes. The obtained results will be compared with previous data of Sn-Ag and Sn-Ag-Cu alloys. To two alloys:  Sn 3.13Ag 0.74Cu and Sn 2.76Ag 0.46Cu ( in atomic percents) various amounts of Bi will be added to observe the influence of Bi on surface tension and interfacial tension at 250⁰ C, and finally to draw the conclusions important from the point of view of practical application analyzing the optimal Bi content in Sn-Ag-Cu-Bi  solders their mechanical properties and wettability.