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Lead-Free Soldering:Lead-Free Soldering:
Phase Relationships and Phase Relationships and
Thermochemistry of Ag-Cu-Ni-SnThermochemistry of Ag-Cu-Ni-Sn
H. Flandorfer, C. Schmetterer, U. Saeed and H. Ipser
Department of Inorganic Chemistry / Materials Chemistry
University of Vienna
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
OutlineOutline
The binary systems
• Phase diagram
• Enthalpy of mixing
The ternary system Ag-Ni-Sn
• Literature
• Difficulties of sample preparation
• Isothermal sections
• Vertical sections and liquidus projection
• Enthalpy of mixing
Conclusions
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
The binary systems Ag-Ni, Ag-Sn and Ni-SnThe binary systems Ag-Ni, Ag-Sn and Ni-Sn
Ag-NiPhase diagram version from Massalski‘s compilation
• 3 samples prepared byarc-melting
• XRD• DTA
No significant deviations!No significant deviations!
A ssessed N i-A g phase diagram .
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
The binary systems Ag-Ni, Ag-Sn and Ni-SnThe binary systems Ag-Ni, Ag-Sn and Ni-Sn
Ag-SnPhase diagram version from Massalski‘s compilation
• 9 samples prepared byarc-melting
• XRD• SEM-EDX• DTA
Good agreement except:Good agreement except:p1 = 489 °C (480 °C)p2 = 729 °C (725 °C)
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
The binary systems Ag-Ni, Ag-Sn and Ni-SnThe binary systems Ag-Ni, Ag-Sn and Ni-Sn
Ni-SnPhase diagram version from Massalski‘s compilation
• 4 samples prepared byarc-melting
• XRD• SEM-EDX• DTA
A ssessed N i-Sn phase diagram.
Significant deviations of transition temperatures, compositionsSignificant deviations of transition temperatures, compositionsand crystal structure of IMC’s!and crystal structure of IMC’s!
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
MixMixH of Ag-Ni, Ag-Sn and Ni-SnH of Ag-Ni, Ag-Sn and Ni-Sn
xAg
0,0 0,2 0,4 0,6 0,8 1,0
M
ixH
J
/mo
l
0
2000
4000
6000
8000
10000
12000
14000
Ni Ag
Ag-NiNo MixH data available in literature.
• Drop calorimetry from both sides with 3 runs each at 1500 °C• Redlich-Kister polynomial applied to fit the experimental data and for interpolation over the liquid miscibility gap
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
MixMixH of Ag-Ni, Ag-Sn and Ni-SnH of Ag-Ni, Ag-Sn and Ni-Sn
Ag-SnSeveral experimental results and compilations available.
• Drop calorimetry from the tin side at various temperatures and from the silver side at 1250 °C• Redlich-Kister polynomial applied to fit the experimental data and extrapolate into the metastable liquid regionxAg
0,0 0,2 0,4 0,6 0,8 1,0
MixH
in k
J/m
ol
-4
-3
-2
-1
0
1
2
500 °C; two runs700 °C900 °C1000 °C
1250 °C
fitted curve at 500 °C
1100 °C
fitted curve at 1250 °C
977 °C [73Hul]
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
MixMixH of Ag-Ni, Ag-Sn and Ni-SnH of Ag-Ni, Ag-Sn and Ni-Sn
Ni-SnA couple of experimental results and compilations available.
• Drop calorimetry from the tin side at various temperatures and from the silver side at 1500 °C• Redlich-Kister polynomial applied to fit the experimental data and extrapolate into the metastable liquid regionxNi
0,0 0,2 0,4 0,6 0,8 1,0
MixH
in
kJ/
mo
l
-25
-20
-15
-10
-5
0
5
1100°C; two runs1250 °C; two runs1500 °C1500 °C; Sn dropped
Haddad et al.Hultgren
fitted curve at 1500 °Cfitted curve at 1250 °Cfitted curve at 1100 °C
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
Literature data for Ag-Ni-SnLiterature data for Ag-Ni-Sn
Experimental and calculated isothermal section at 240 °C:
Hs.-F. Hsu and S.-W. Chen, Acta Mater. 52(9), 2541 (2004)• 33 samples prepared from arc-melting• EPMA and XRD
Calculated isothermal section at 230 °C:
G. Ghosh, J. Electron. Mater. 29, 1182 (2000)
Experimental liquidus projection:
S.-W. Chen, Hs.-F. Hsu and Ch.-W. Lin, J. Mater. Res. 19(8), 2262 (2004) 73 samples prepared from arc-melting Metallography and EPMA (for primary crystallization investigations) DTA (for 11 samples only)
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
Phase diagram investigations
• ~ 130 samples, prepared using different methods, annealed at different temperatures, quenched or slowly cooled
• XRD, LOM, SEM, EPMA, DTA, DSC, Heat-flow DSC• 4 isotherms at 200, 450, 700, 1050 °C• 9 isopleths, liquidus surface projection, reaction scheme
Enthalpy measurements
• Two Tian-Calvet type drop calorimeter from 200 to 1500 °C• Drop calorimetry along 12 ternary sections with 11 – 24 drops each• Measurement temperatures were 1000, 1220 and 1400 °C• Redlich-Kister-Muggianu polynomial fit with ()M for the 3 temperatures
Experiments and achievementsExperiments and achievements
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
Sample preparation in Ag-Ni-SnSample preparation in Ag-Ni-Sn There are two main problems:
• The miscibility gap which extends from the binary Ag-Ni far into the ternary• Evaporation during arc-melting and DTA in the Ni-rich part
Solution: Samples up to app. 35 at.% Sn have been prepared from Ni-, Ni3Sn and Ag3Sn powders. They were annealed at the respective temperatures, re-powdered and annealed again up to three times.
1 cm 20 µm
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
1050 °C
Isothermal sectionsIsothermal sections
200 °C
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
240 °C
Comparison with a literature diagramComparison with a literature diagram
this work H.-F. Hsu and S.-W. Chen
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
IsoplethsIsopleths
35 at.% Sn
60 at.% Sn
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
Enthalpy of mixingEnthalpy of mixing
0.00
0.25
0.50
0.75
1.00Sn
0.00
0.25
0.50
0.75
1.00
Ag
0.00 0.25 0.50 0.75 1.00
Ni
-4
-2
-2
26 12108
4
0
0
-12-20
-18
-16
-14
-10-8
-6
1000 °C
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
Phase limits from calorimetryPhase limits from calorimetry
0 10 20 30 40 50 60 70 80 90 1000
10
20
30
40
50
60
70
80
90
1000
10
20
30
40
50
60
70
80
90
100
NiAg
Sn
1220°C
1400°C
1000°C
Exp. points from kinks in enthalpy curvesIsothermExtension of liquid miscibility gap at 1220 and 1400°C.Maximum extension of the miscibility gap [07Sch]
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
ConclusionsConclusions
• The quality of experimental and calculated higher order phase diagrams is limited by the quality of the constituent binary’s.
• Also well established and widely used binary phase diagram compilations and assessments can exhibit essential errors. A careful check of original literature data and a few experiments should be done.
• CALPHAD method is powerful to check the consistency of different experimental data and to present phase diagrams and thermochemical data. The predicting power, however, is very low,
specially for binary and ternary systems.
• Based on all experimental data available now an optimized data set for Ni-Sn and Ag-Ni-Sn can be established.
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007
AcknowledgementsAcknowledgements
Thanks to:Thanks to:
• All my colleagues of the Materials Chemistry Departmentfor the excellent collaboration
• The FWF for financing the project No. P-16495-N11
• All the co-operation partner of the project and COST-531 Action
COST 531 Final Meeting Vienna, Austria May 17 - May 18, 2007