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THERMODYNAMICS OF LEAD FREE Bi-Sn SOLDER ALLOYS WITH Ni and Cu

THERMODYNAMICS OF LEAD FREE Bi-Sn SOLDER ALLOYS WITH Ni and Cu. S. Amore , S. Delsante, E. Puzo, G. Borzone Department of Chemistry and Industrial Chemistry (DCCI) University of Genoa (Italy). Final Meeting COST Action 531 Vienna 17-18 May 2007. Introduction. Solder system Bi-Sn.

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THERMODYNAMICS OF LEAD FREE Bi-Sn SOLDER ALLOYS WITH Ni and Cu

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  1. THERMODYNAMICS OF LEAD FREE Bi-Sn SOLDER ALLOYS WITH Ni and Cu S. Amore, S. Delsante, E. Puzo, G. Borzone Department of Chemistry and Industrial Chemistry (DCCI) University of Genoa (Italy)

  2. Final Meeting COST Action 531 Vienna 17-18 May 2007 Introduction Solder system Bi-Sn Substrates Ni, Cu • Interactions between Pb-free solder alloys and substrates • Study of the interfacial reaction between Bi-Sn alloy and Ni, Cu substrate • Study of the wetting properties (contact angle and interfacial reaction) of Bi-Sn system on Cu and Ni • Comprensive understanding of the phase equilibria and thermodynamic properties Literature works On going @IENI-CNR Genova This work Measurments of partial enthalpy at infinite dilution of solid Ni and Cu in liquid Bi-Sn

  3. Final Meeting COST Action 531 Vienna 17-18 May 2007 Experimental • Dissolution Calvet Calorimeter • Pure Ar flux (6l/h) • Graphite crucible • Ta getter • Real time acquisition of Heat Flow, calorimeter temperature (S-type thermocouple) and room temperature (K-type thermocouple); scan rate 1s • Samples • Pure elements mechanically a chemically cleaned • Mass of bath about 20g • After each experiment thermodynamic equilibrium checked by SEM-EDS analysis Appropriate software in LabView environment

  4. Final Meeting COST Action 531 Vienna 17-18 May 2007 Bi-Sn-X (X=Ni,Cu) system Ni-Sn Bi-Sn TB Massalski Binary Alloy Phase Diagrams vol 1,2 H. Ipser, et al, J Mater Sci: Mater Electron (2007) 18:3–17 Cu-Sn Bi-Ni

  5. Final Meeting COST Action 531 Vienna 17-18 May 2007 Literature Data Integral enthalpy of mixing Sn-Ni system Partial Enthalpy of mixing of Ni in liquid Sn at T=773 K approx -60kJ/mol H. Ipser, H. Flandorfer, Ch. Luef, C. Schmetterer, U. Saeed, J Mater Sci: Mater Electron (2007) 18:3–17

  6. Final Meeting COST Action 531 Vienna 17-18 May 2007 Bi-Sn-Ni experimental results Partial enthalpy of mixing at infinite dilution for Ni in liquid Bi-57at%Sn alloy T= 820 K • Nominal composition of the bath Bi-57at%Sn • Drop of Ni with 0.01g<mNi<0.03g • 0<x(Ni)<0.015 • 4 different runs in same conditions

  7. Ni3Sn4 Eutectic at 57at%Sn Final Meeting COST Action 531 Vienna 17-18 May 2007 Bi-Sn-Ni experimental results Calorimetric sample after measure at T= 820 K Bi36at%-Sn63at%-Ni1at% Change of the composition due to the evaporation of Bi p0Bi (T=800K) ≈ 4 10-8 atm p0Sn (T=800K) ≈ 4 10-10 atm

  8. J. Wang, H.S. Liu, Z.P. Jin, J. Electronic Materials 35 (2006) 10 Final Meeting COST Action 531 Vienna 17-18 May 2007 Bi-Sn/Ni interfacial reaction T=423K Bi-91at%Sn Bi-64at%Sn Bi-43at%Sn

  9. V.I. Dybkov, K. Barmak, w. Lengauer, P. Gas, Journal of Alloys and Compounds 389 (2005) Final Meeting COST Action 531 Vienna 17-18 May 2007 Bi/Ni interfacial reaction T=423K Pure liquid Bi in contact with solid Ni Formation of the NiBi3 phase

  10. Final Meeting COST Action 531 Vienna 17-18 May 2007 Bi-Sn-Ni experimental results “Calorimetric” sample after measurement at T= 820 K Bi36at%-Sn63at%-Ni1at% NiBi3 Ni3Sn4

  11. Final Meeting COST Action 531 Vienna 17-18 May 2007 Bi-Sn-Ni experimental results Sample annealed at 820 K and then quenched in cold water Bi37at%-Sn62at%-Ni1at% Change of the composition due to the evaporation of Bi p0Bi (T=800K) ≈ 4 10-8 atm p0Sn (T=800K) ≈ 4 10-10 atm Primary cristals Ni3Sn4

  12. Final Meeting COST Action 531 Vienna 17-18 May 2007 Bi-Sn-Cu experimental results Partial enthalpy of mixing at infinite dilution for Cu in liquid Bi-57at%Sn alloy T= 820 K • Bi-57at%Sn + Cu • 4 different runs in same conditions • 0<x(Cu)<0.018

  13. Final Meeting COST Action 531 Vienna 17-18 May 2007 Bi-Sn-Cu literature data Integral enthalpy of mixing Bi-Sn-Cu system The literature data of the integral enthalpy of mixing confirm the endothermic value of the partial enthalpy of mixing of Cu in liquid Bi-Sn at a composition near to the eutectic H. Ipser, H. Flandorfer, Ch. Luef, C. Schmetterer, U. Saeed, J Mater Sci: Mater Electron (2007) 18:3–17

  14. Final Meeting COST Action 531 Vienna 17-18 May 2007 Bi-Sn-Cu experimental results “Calorimetric” sample after measurement at T= 820 K Bi36at%-Sn62.5at%-Cu1.5at% Primary cristals Eutectic at 57at%Sn h-phase Cu6Sn5

  15. Final Meeting COST Action 531 Vienna 17-18 May 2007 Bi-Sn-Ni experimental results Partial enthalpy of mixing at infinite dilution for Ni and Cu in liquid Bi-61at%Sn alloy

  16. Final Meeting COST Action 531 Vienna 17-18 May 2007 Conclusions Results • Exothermic partial enthalpy of mixing of Ni in liquid Bi-Sn at composition near to the eutectic • Endothermic partial enthalpy of mixing of Cu in liquid Bi-Sn at composition near to the eutectic Difficulties • Change of the composition due to the evaporation of Bi during the experiment Future Work • Measurements of the partial enthalpy of mixing for Bi-Sn-X (X=Cu,Ni) at different temperatures • Study of wetting behaviour of Bi-Sn alloys on Cu and Ni substrates

  17. Università di Genova Department of Chemistry and Industrial Chemistry Prof. Gabriella Borzone – Group leader Dr. Nadia Parodi – Senior Scientis Dr. Simona Delsante – Post Doc Stefano Amore – Ph.D. Enrico Puzo – SEM EDS technician

  18. Thank you for your attention

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