Transcript THERMODYNAMICS OF LEAD FREE Bi

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)
Introduction
• Interactions between Pb-free solder alloys and substrates
Solder system
Substrates
Bi-Sn
Ni, Cu
Literature works
 Study of the interfacial reaction between Bi-Sn alloy and Ni, Cu substrate
 Study of the wetting properties (contact angle and interfacial reaction) of
On going
Bi-Sn system on Cu and Ni
@IENI-CNR Genova
 Comprensive understanding of the phase equilibria and thermodynamic
properties
This work
Measurments of partial enthalpy at
infinite dilution of solid Ni and Cu in
liquid Bi-Sn
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 (Ktype 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
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
Bi-Ni
H. Ipser, et al, J Mater Sci: Mater Electron (2007) 18:3–17
Cu-Sn
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
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
40
Drop of Ni with 0.01g<mNi<0.03g
0<x(Ni)<0.015
4 different runs in same conditions

 sol H  (20.4  1.0)kJ / mol
solH° [kJ/mol]
20
0
-20
-40
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.020
x(Ni)
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%
Ni3Sn4
Change of the composition
due to the evaporation of Bi
p0Bi (T=800K) ≈ 4 10-8 atm
p0Sn (T=800K) ≈ 4 10-10 atm
Eutectic at 57at%Sn
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
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/Ni interfacial reaction
T=423K
Pure liquid Bi in
contact with solid Ni
Formation of the NiBi3
phase
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-Sn-Ni experimental results
“Calorimetric” sample after measurement at T= 820 K
Bi36at%-Sn63at%-Ni1at%
NiBi3
Ni3Sn4
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
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
40
•Bi-57at%Sn + Cu
•0<x(Cu)<0.018
solH [kJ/mol]
•4 different runs in
same conditions
20
0
-20

 sol H  (8.9  1.0)kJ / mol
-40
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.020
x(Cu)
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
solH°[kJ/mol]
8000
6000
4000
2000
H. Ipser, H. Flandorfer, Ch. Luef, C. Schmetterer,
U. Saeed, J Mater Sci: Mater Electron (2007) 18:3–17
0
0.0
0.2
0.4
x(Cu)
0.6
0.8
1.0
Final Meeting COST Action 531 Vienna 17-18 May 2007
Bi-Sn-Cu experimental results
Bi36at%-Sn62.5at%-Cu1.5at%
“Calorimetric” sample after measurement at T= 820 K
Primary cristals
Eutectic at 57at%Sn
h-phase Cu6Sn5
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
40
20
 sol H  (8.9  1.0)kJ / mol

 sol H  (20.4  1.0)kJ / mol
solH [kJ/mol]

Cu
0
Ni
-20
-40
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
0.016
0.018
0.020
x(Ni,Cu)
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
Final Meeting COST Action 531 Vienna 17-18 May 2007
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
Thank you for your attention