Bi-Sn-Zn & Pd-Sn-Zn Systems: Summary of the Results

1. Bi-Sn-Zn & Pd-Sn-Zn Systems:Summary of the Results Pb Phase Equilibria 1Department of Inorganic Chemistry / Materials Chemistry Faculty of Chemistry University of Vienna Vienna, Austria in Lead-free solders 2Structure of Phases Group Department of Structure Institute of Physics of Materials, AS CR Brno, Czech Republic Jiri Vizdal1 and Ales Kroupa2

2. Presentation outline • Aims + used methodology • Experimental methods summary • Results… • Bi-Sn, Bi-Zn, Bi-Sn-Zn • Pd-Zn, Pd-Sn-Zn • Conclusions

3. Our work was aimed at thermodynamic and experimental description of phase equilibria in the Bi-Sn-Zn, Pd-Sn-Zn (Pd – Pd/Ni substrate coatings) systems and relevant subsystems >>> contribution to new Pb-free solders design Analysis + literature survey: optimal thermodynamic assessments selection (if exist!) 1. version of the thermodynamic database Theoretical study („CALPHAD“ -> Thermo-Calc): predictions calculations Experimental study (SEM + EDS/WDS, DTA/DSC, etc.) Theoretical study: modelling -> „COST531“ thermodynamic database expansion Aims & methodology Our goals and how to achieve them...

4. Materials, treatment Bi, Sn, Zn, Pd ≥ 99,95 % Samples were sealed under vacuum into quartz capsules. Homogeneity {SEM (BSE) + EDS}. Heat treatment – annealing (different T, t). Coolant: H2O. Phase identification and composition measurement. >>> Phase transformations temperatures measurement. >>> Exp. methods SEM + EDS/WDS(JEOL JSM-6460; BSE; 20 keV / INCA + standards + ZAF) TEM + EDS(TEM/STEM Philips CM 12 / EDAX Phoenix CM 12) DTA/DSC(Netzsch DTA/DSC 404; Dept. of Inorganic Chemistry / Materials Chemistry, University ofVienna): standards: Au/Ag vheating/cooling ~ 2 °C/min. accuracy: ±2 °C atmosphere: vacuum/Ar Experimental details Exp. methods summary

5. Experimental & TheoreticalResults

6. TE ~ 138.4 °C Calculated activity of Sn in Liq. in comparison to exp. data from Asryan & Mikula[ASR 2004] Enthalpy of mixing in comparison to experimental data from [ASR 2004] and [SHARKEY 1972] Newly modified Bi-Sn system description, that was originally published by[OHT 1994] Bi-Sn: optimization results Bi-Sn: Final assessment [COST2006]

7. SEM/WDS Overall compos. Bi-76.2Zn Bi in HCP_Zn (Zn) 0.3  0.2 Zn in (Bi) 0.3  0.1 Values in wt. % Liq. Liq. + (Zn) (Bi) + (Zn) Malakhov [MAL 2000] After change Malakhov [MAL 2000]: 35 000 J/mol Optimization: 25 000 J/mol Annealed 864 h/200 °C Bi-Zn: assessment correction Bi-Zn: Final assessment

8. Bi/Zn = 1/2 w(Sn) = 59 hm. % T = 120 °C T1 + + T2 A B (Bi) + (Sn) + (Zn) Liq. + (Zn) Liq. + (Zn) [This work] Liq. + (Sn) + (Zn) (Sn) + (Zn) [BRA 2007] D A (Bi) + (Sn) + (Zn) (Bi) + (Sn) + (Zn) C E B x(Zn) = 5 at. % w(Zn) = 12 hm. % Isothermal section (120 °C) together with selected vertical sections compared to available experimental data… Liq. + (Sn) + (Zn) (Bi) + (Zn) (Sn) + (Zn) Liq. + (Bi) + (Zn) Liq. + (Zn) [BRA 2007] [LUEF 2006] (Bi) + (Sn) + (Zn) (Bi) + (Sn) + (Zn) Bi-Sn-Zn:selected isopleths At. % Bi-Sn-Zn: New assessment [COST 2006]

9. 1 2 3 4 Activities in comparison to exp. data from [OLE 1959] Enthalpies of mixing compared to exp. data from [LUEF 2006] Bi-Sn-Zn:therm. properties Bi-Sn-Zn: New assessment [COST 2006]

10. Massalski’s experimental phase diagram [MASS 1990] Phase diagram by Hansen and Anderko [HAN 1958] ? ? • Thermodynamic activities of Zn in ordered β1 Pd-Zn alloys at 1000 °C were measured by Kou and Chang [KOU 1975]. • Partial molar and integral properties were determined from vapour pressure measurements by Chiang [CHI 1977] (477 – 1030 °C / 0 – 83 at. % Zn). Pd-Zn: overview Pd-Zn: The reason of study [E-MRS 2005]

11. Pd-Zn phase diagram, calculated on the basis of newly optimized thermodynamic parameters in comparison with available exp. data. The detail of the phase diagram showing new exp. information – marked invariant reactions (DTA) and phase‘s composition (SEM + EDS). Pd-Zn: phase diagram Pd-Zn: New assessment [E-MRS 2005]

12. Comparison of exp. measured [CHI 1977] and calculated values of: • Zn activities in (Pd); • integral molar Gibbs energy for the Pd-Zn system at 1000 °C in different concentration ranges. Pd-Zn: therm. properties Pd-Zn: New assessment [E-MRS 2005]

13. 500 °C 900 °C Calculated isothermal sections in the Pd-Sn-Zn system at 500 and 900 °C based only on binary data together with marked exp. alloys. Pd-Sn-Zn: prediction + exp. Binary prediction + proposed exp. alloys

14. 500 °C 900 °C Preliminary experimental phase diagrams design – isothermal sections constructed according to SEM/TEM + EDS marked experimental results. Pd-Sn-Zn: SEM/TEM + EDS Experimental phase diagram

15. Conclusions

16. Conclusions… • Bi-Sn-Zn system and relevant subsystems: • Exp. determined max. solubility of Bi in (Sn) at TE ~ 10 wt. % -> created new assessment of the Bi-Sn system. • Exp. determined solubilities of Bi in (Zn) and Zn in (Bi) at T = 200 °C -> correction of the present Bi-Zn assessment. • Exp. study of the Bi-Sn-Zn system (SEM + EDS/WDS, DTA) -> own results + results from literature were used for the new assessment (interact. param. for Liq. and (Bi)). • Pd-Zn and Pd-Sn-Zn systems: • Exp. study of Zn-rich part of the Pd-Zn phase diagram verified presence of the η-phase at T = 400 °C. • Eutectic reaction was established in this part of the Pd-Zn diagram: Liq.  η + (Zn). • First thermodynamic description of the Pd-Zn system has been created. • First predictions within the Pd-Sn-Zn system were calculated and relevant exp. results at 500 a 900 °C were obtained. These were used for the preliminary exp. phase diagram construction. • Presented finished thermodyn. descriptions of the Bi-Sn, Bi-Zn, Pd-Zn and Bi-Sn-Zn systems are in very good agreement with available data and sets of thermodynamic parameters were included in the „COST531“ database.

17. <<< Publications Cooperation: • Dr. Milan Svoboda (IPM AS CR) • Prof. Klaus W. Richter(University of Vienna) • Dr. Christoph Luef (University of Vienna) • Prof. Aloke Paul (Indian Institute of Science) • Prof. M. H. Braga (Universidade do Porto) • Prof. L. F. Malheiros (Universidade do Porto) • Prof. D. Soares (Universidade do Minho) Acknowledgements This work was supported by following projects: • COST No. OC 531.002 (Ministry of Education of the Czech Republic) • No. 106/05/H008 (Czech Science Foundation) • AV0Z20410507 (Research project)

18. Literature [COST 2006]Vizdal, J., Braga, M.H., Kroupa, A., Malheiros, L.F., Soares, D.: In COST 531 Mid-Term Meeting, Genoa, Italy, 2006. [ASR 2004]Asryan, N., Mikula, A.: Z. Metallkd. 95 (2004). [SHARKEY 1972]Sharkey, R.L., Pool, M.J.: Met. Trans. 3 (1972). [OHT 1994]Ohtani, H., Ishida, K.: J. of El. Mat. 23 (1994). [OEL 1958]Oelsen, W., Golücke, K.F.: Arch. Eisenhüttenw. 29 (1958). [NAG 1952]Nagasaki, S., Fujita, E.: J. Jpn. Inst. Met. 16 (1952). [MAL 2000]Malakhov, D.V.: Calphad 24 (2000). [BRA 2007]Braga, M.H., Vizdal, J., Kroupa, A., Ferreira, J., Soares, D., Malheiros, L.F.: Calphad, accepted for publication, 2007. [LUEF 2006]Luef, Ch., Paul, A., Vizdal, J., Kroupa, A., Kodentsov, A., Ipser, H.: Monatsh. Chem. 137 (2006). [OLE 1959]Oleari, L., Fiorani, M.: L. Ricerca Scientifica 29 (1959). [E-MRS 2005]Vizdal, J., Kroupa, A., Popovic, J., Zemanova, A.: In E-MRS int. Fall Meeting, p. 177, ISBN 83-89585-07-3, Warsaw, Poland, 2007. [MASS 1990] Massalski, T.B.: Binary Alloy Phase Diagrams, ASM Int., Ohio, USA 1990. [HAN 1958] Hansen, M., Anderko, K.: Constitution of Binary Alloys, New York, 1958. [KOU 1975] Kou, S., Chang, Y.A.: Acta Metall. 23 (1975). [CHI 1977] Chiang, T., et al.: Z. Metallkd. 68 (1977).