Surface properties and wetting characteristics of lead-free solder alloys E. Ricci, D. Giuranno, F....
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Transcript of Surface properties and wetting characteristics of lead-free solder alloys E. Ricci, D. Giuranno, F....
Surface properties and Surface properties and wetting characteristics of wetting characteristics of
lead-free solder alloyslead-free solder alloys
E. Ricci, D. Giuranno, F. Gnecco, S. Amore, T. Lanata, R. Novakovic
National Research Council (CNR) – Institute for Energetics and Interphases (IENI)Genoa - Italy
Contribution from IENI Genova to COST 531Contribution from IENI Genova to COST 531
Characterization Surface Properties and wetting behaviour of Selected groups of Lead-free Alloys as
Soldering Materials
Surface Tension + modelling: Binary systems Ag-Cu Au-Sn
Cu-Sn Au-InIn-Sn Bi-In
Wetting behaviour:Ternary systems: Au-In-Sn/Cu
Bi-In-Sn/CuBinary sub-systems: Au-In/Cu
Bi-In /CuAu-Sn/(Cu,Ni)In-Sn /(Cu,Ni)Cu-Sn/(Cu,Ni)
Final Meeting COST Action 531 Vienna 17-18 May 2007
Preparation of the samplesPreparation of the samples
Preparation of the alloys from the pure elements by melting in a clean atmosphere
Control of alloys compositions by SEM-EDS
Mass of alloy sample mechanical and chemical cleaned
3.0 g ST measurements
1.0 g wetting experiments
Working ConditionsWorking Conditions
Sapphire crucible
Clean Conditions
Flux Ar N60 atmosphere 10-4 <
PO2<10-2 Pa; Vacuum conditions Ptot ≈
10 -5 Pa
Tl+ 50 K <Texp< 1300 K
Surface Tension MeasurementsSurface Tension Measurements
Cu, Ni square plate
(13x13x1mm) metallogrhaphically
mirror polished (Ra<0.05 mm)
Ar N60 atmosphere PO2 ≤ 10-6 Pa
Texp = Tl+ 50 K up to 900K
Wetting ExperimentsWetting Experiments
ExperimentalExperimental
Final Meeting COST Action 531 Vienna 17-18 May 2007
ExperimentalExperimental
Surface TensionSurface Tension
Contact AnglesContact Angles
Acquisition of drop profile in real time (2 s) by ASTRAview®
appropriate Software
Oxygen Partial Pressure
Temperature
Final Meeting COST Action 531 Vienna 17-18 May 2007
SV = LS + LV cos
< 90°wettability
> 90° no wettability
S
V
LV
LS
Liquid
Final Meeting COST Action 531 Vienna 17-18 May 2007
Surface Tension ResultsSurface Tension Results
Temperature [K]
1273 1323 1373 1423 1473 1523
Sur
face
Ten
sion
[mN
/m]
400
500
600
700
800
900
1000
1100
1200
pure Au
6.1 at %Sn
11.8 at% Sn
37.8 at% Sn
54.1 at% Sn
81.8 at% Sn
95.3 at% Sn
pure Sn
Temperature [K]
1273 1323 1373 1423 1473 1523
Sur
face
tens
ion
[mN
/m]
400
500
600
700
800
900
1000
1100
1200
pure Au
9.9 In at%
30.0 In at%
36.4 In at%
49.5 In at%54.9 In at%
88.7 In at%
pure In *
Experimental determination of the surface tension
Theoretical calculations of the surface tension
Experimental data are in good agreement with surface tension values calculated using different theoretical modelsExperimental data are in good agreement with surface tension values calculated using different theoretical models
Surface tensionSurface tension
Final Meeting COST Action 531 Vienna 17-18 May 2007
at%
Au
at%
Au
at%
Au
at%
Au
Au-InAu-InAu-InAu-In Au-SnAu-SnAu-SnAu-Sn
Experimental determination of the surface tension
Theoretical calculations of the surface tension
Experimental data are in good agreement with surface tension values calculated using different theoretical modelsExperimental data are in good agreement with surface tension values calculated using different theoretical models
Surface tensionSurface tension
Final Meeting COST Action 531 Vienna 17-18 May 2007
Temperature [K]
573 673 773 873
Su
rfa
ce T
en
sio
n [
mN
/m]
350
400
450
500
550
pure In95.0 at% In
85.0 at% In79.5 at% In
67.5 at% In
51.5 at% In
36.5 at% In30.0 at% In
15.5 at% In
5.0 at% Inpure Bi
at%
Inat%
In
In
Bi
at%
Inat%
In
Temperature [K]
600 650 700 750 800 850 900 950
Su
rfa
ce
te
ns
ion
[m
N/m
]
500
510
520
530
540
550
560
In 100
In 79.49
In 51.70
Sn 100
In 50.08
In 29.685
In 14.47
In 85.36
In 67.62
In 36.63
Bi-InBi-InBi-InBi-In In-SnIn-SnIn-SnIn-Sn
Temperature [K]
600 800 1000 1200 1400 1600
Su
rfa
ce
Te
ns
ion
[m
N/m
]
400
600
800
1000
1200
1400
Surface tensionSurface tensionCu-SnCu-SnCu-SnCu-Sn
at%
Cu
at%
Cu
Experimental determination of the surface tension
Theoretical calculations of the surface tension Final Meeting COST Action 531 Vienna 17-18 May 2007
at%
Cu
at%
Cu
Ag-CuAg-CuAg-CuAg-Cu
T=1373K
1 REG. SOL2 Prasad’smodel
□ □ Exp Results
Wetting ResultsWetting Results
Final Meeting COST Action 531 Vienna 17-18 May 2007
Wetting ResultsWetting Results
Final Meeting COST Action 531 Vienna 17-18 May 2007
Composition [at%]Composition [at%] Temperatures [K]Temperatures [K] SubstratesSubstrates
TTll TTff
NiNi CuCuff[°][°] ff [°] [°]
In-70SnIn-70Sn 450 710 20 41
In-85SnIn-85Sn 529 710 30 23
Au – 55 InAu – 55 In 768 852 50
Au – 97 InAu – 97 In 588 760 21
Au-82SnAu-82Sn 582 710 23 34
Cu-70SnCu-70Sn 813 910 26 <5
Cu-80SnCu-80Sn 743 910 25 <5
Cu – 90 SnCu – 90 Sn 653 910 10
Cu-95SnCu-95Sn 583 910 <5 <5
Bi – 52 InBi – 52 In 383 623 51Bi – 80 InBi – 80 In 355 648 44
Au – 5 In – 81 SnAu – 5 In – 81 Sn 538 645 33
Au – 11 In – 84 SnAu – 11 In – 84 Sn 493 600 52
Au – 8 In – 88 SnAu – 8 In – 88 Sn 503 602 23 39
Bi – 5 In – 81 Sn 483 608 39
Bi – 8 In – 88 Sn 430 608 30
60 m
In – 70SnIn – 70Sn
-Cu3Sn based phase
Ni substrateNi substrate
14 mNi3Sn4 based phase
-Cu6Sn5 based phase
Interface Characterization Interface Characterization
Final Meeting COST Action 531 Vienna 17-18 May 2007
Cu substrateCu substrate
As Pb-Sn solder alloys these systems showAs Pb-Sn solder alloys these systems show::
Formation of a layer (<100 m) of intermetallic compounds at the interface between solder alloys and substrate
These reactions are dominated by the Sn-component, but the and the -phase are exchanged
Similar behaviour:
•Cu-Sn/Ni•Au-In-Sn/Cu
CuCu
Au-55In
Final Meeting COST Action 531 Vienna 17-18 May 2007
Excessive dissolutive wetting
Similar behaviour:
•Cu-Sn/Cu
Interface Characterization Interface Characterization
Erosion of the substrate and Increase in the total volume
of liquid phase
Negative influence Negative influence on mechanical and on mechanical and
electrical properties electrical properties
Cu substrateCu substrate
Final Meeting COST Action 531 Vienna 17-18 May 2007
CuCu
BiIn2
Bi-52In
Interface macroscopically planar Similar behaviour:
•Au-Sn/(Cu,Ni)
•Bi-In-Sn/Cu
Interface Characterization Interface Characterization
Weakness of solder jointWeakness of solder joint
Cu substrateCu substrate
Final Meeting COST Action 531 Vienna 17-18 May 2007
ConclusionsConclusions
Complete characterization of the surface properties and the wetting behaviour of
selected groups of lead-free solder alloys
In-Sn and Cu-Sn are good candidates as basic systems for new lead free solders concerning their wettability on Cu and Ni
The additional elements should be chosen in order to preserve the wetting properties to exchange the and phase formation at the interface, and inhibit the excessive growth of a reactive layer keeping good mechanical and electrical properties
Final Meeting COST Action 531 Vienna 17-18 May 2007
Thank for your attentionThank for your attention