Thermodynamics and Phase Diagram of the Ni-Sb-Sn System

Ratikanta Mishra & Herbert Ipser

Department of Inorganic Chemistry / Materials Chemistry,

University of Vienna, Austria

TOFA-2010 Sept. 12-16

Traditional Solder Materials

As examples:

� Sn-Pb (62/38 wt.%)

232°C

327.5°C

183°C

� High-lead solders

(up to 90 % Pb) for

“high-temperature

soldering”

SnPb

eutectic

(38/ 62)(90/10)

TOFA-2010 Sept. 12-16

• Search is on for possible lead-free alloys with melting point between 250 and 400°C.

• It is now widely agreed that there is no drop-in replacement for the standard tin-lead solders

• Sn-Sb alloys with additional alloying elements Ag, Cu, Ni can be a possible candidate for new high-

• Sn-Sb alloys with additional alloying elements Ag, Cu, Ni can be a possible candidate for new high-temperature solders.

• The present work deals with the phase diagram and thermodynamic studies Ni-Sb-Sn system

TOFA-2010 Sept. 12-16

Overview

�Thermal analysis of SnThermal analysis of SnThermal analysis of SnThermal analysis of Sn----rich cornerrich cornerrich cornerrich corner

� Phase Diagram NiPhase Diagram NiPhase Diagram NiPhase Diagram Ni----SbSbSbSb----Sn system at 900Sn system at 900Sn system at 900Sn system at 900°°°°CCCC� Phase Diagram NiPhase Diagram NiPhase Diagram NiPhase Diagram Ni----SbSbSbSb----Sn system at 900Sn system at 900Sn system at 900Sn system at 900°°°°CCCC

�Thermodynamics of NiThermodynamics of NiThermodynamics of NiThermodynamics of Ni----SbSbSbSb----Sn systemSn systemSn systemSn system

TOFA-2010 Sept. 12-16

Thermal analysis of Sn -rich corner

RTCC

CCCRTquenchd

hdh

→°→°

°→°→°→

200200

2001050105021

1273

Isothermal sections at 200C.

Samples : 20Ni: 0-25 at %Sb: 0 to 25 at %Sn: 95-75 at %

Heat Treatment:

Isothermal sections at 200C. DTAXRD EPMAHigh resolution microscopeIsopleths Scheil diagram Liquidus projection

TOFA-2010 Sept. 12-16

EPMA & XRD Results

At %Sb

Invariant Temperature(°C)

Other Temperature(°C)

0 232.5, -- ---, 800

2.5 232.5, 243 --, 793

5 233, 243 --, 775

DTA results of 80% Sn alloys

Isopleth for 80 % at Sn 200 °C

7.5 233, 242, 249 248, 743

10 232, 243, 250 263, 684

12.5 233, 244, 251 282, 635

15.0 233, 243, 251 285, 539

17.5 232.5, 243, 252 286, 388

At % Sb

Invariant Temperature(°C)

Other Temperature(°C)

0 231.5, --, -- -- , 780

2.5 231.5, 243, -- -- , 743

5 232, 244, -- 249, 713

DTA results of 85% Sn alloys

7.5 233, 242, 250 295, 634

10 232, 243, 251 319, 517

12.5 233, 242, 252 -- . 344

Isopleth for 85 % at Sn 200 °C

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Experimental Results: Scheil Diagram Sn-rich corner

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Liquidus projection

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Phase diagram Ni-Sb-Sn system at 900

Samples : 30 Heat Treatment:

RTCCKCRT

pelletingGrindingRTCCRTquenchingweekshhh

hdh

→° →°→→°→

→→°→°→

90090010501050

&1050105026963

273

Samples were analyzed by(XRD and EPMA)

TOFA-2010 Sept. 12-16

4.00

4.04

4.08

4.12

4.16

5.18

5.20

5.22

5.24

5.26

a (°A

)

(c)

(a)

c (

°A)

XRD data Ni3Sn2-NiSb tie line

1.29

1.30

1.31

c/a

c/a plot Ni 3Sn2 phase as a function of composition

0.0 0.2 0.4 0.6 0.8 1.0

3.92

3.96

5.14

5.16

5.18

Mole frac. NiSb

(c)

0.0 0.2 0.4 0.6 0.8 1.0

1.27

1.28c/a

Mole frac. NiSb

Phase diagram Ni-Sb -Sn system at 900 °C

L12

The liquidus phase boundary is being determined by DTA

TOFA-2010 Sept. 12-16

Thermodynamic Investigation of Thermodynamic Investigation of NiNi--SbSb--Sn system by Isopiestic Sn system by Isopiestic

Vapor Pressure MethodVapor Pressure MethodVapor Pressure MethodVapor Pressure Method

Isopiestic Vapor Pressure MeasurementIsopiestic Vapor Pressure MeasurementOf NiOf Ni--SnSn--Sb systemSb system

pure Sb

p °(T )

Conditions for Ni-Sn-Sb system fulfilled: pNi, pSn << pSb an

pure Sb

pSb°(TR)

Before equilibration

After equilibration

Ni-Sn alloys

Reservoir, TR (TS > TR)

pSb°(TR)

alloy NixSnySbz

pSb(TS)

In equilibrium: pSb(TS) = pSb°(TR)

Temp.

TOFA-2010 Sept. 12-16

Quartz seal

Ni-Sb-Sn alloy

Quartz crucible

Quartz outer tubeIsopiestic Apparatus

Ni3Sn

Ni3Sn2

Ni3Sn4

(up to 36 crucibles 12 each)

Quartz reservoir

Quartz spacer

Quartz crucible holderQuartz thermo-well

Quartz crucible

Sb

(up to 36 crucibles 12 each)

TOFA-2010 Sept. 12-16

TwoTwo--zone furnace for equilibrationzone furnace for equilibration

S-type thermocouple

Stepper motor arrangementfor controlled raising of thermocouple

Two zone gradient furnace

PC based DAS(Data acquisition system)

TOFA-2010 Sept. 12-16

height of the furnace

1200 mm

Furnace characteristics & Temperature profileIsopiestic apparatus

~ 600 mm

0 50 100 150 200 250 300 350 400950

1000

1050

1100

1150

1200

1250

1300

Sam

ple

Tem

p. (

K)

Distance (mm)

979 K

0 100 200 300 400900

1000

1100

1200

1300

Sam

ple

Tem

p. (

K)

Distance (mm)

Tr= 979 K Tr=1090 K Tr=1017 K Tr=939 K Tr=1072 K

TOFA-2010 Sept. 12-16

After equilibration After equilibration quenching of the entire quenching of the entire apparatus in apparatus in cold watercold water

TOFA-2010 Sept. 12-16

Isopiestic equilibrium curves For Ni3Sn-Sb, Ni3Sn2-Sb and Ni3Sn4-Sb systems

Ni3Sn2-Sb systemNi3Sn-Sb system

0.3 0.4 0.5 0.6 0.7 0.8 0.9900

1000

1100

1200

1300

1400 Tr = 979 K Tr = 1090 K Tr= 1017 K Tr = 939 K Tr = 1072 K

Ts,

K

0.4 0.5 0.6 0.7 0.8 0.9975

1050

1125

1200

1275

1350 Tr = 979 K Tr = 1090 K Tr = 939 K Tr = 1072 K

Ts

(K)

Ni3Sn4-Sb system

0.3 0.4 0.5 0.6 0.7 0.8 0.91000

1100

1200

1300 Tr=1017 K Tr= 939 K Tr = 1072 K

TS

(K)

At. Fraction Sb

TOFA-2010 Sept. 12-16

0.3 0.4 0.5 0.6 0.7 0.8 0.9

At. fraction Sb

0.4 0.5 0.6 0.7 0.8 0.9

At. frac. Sb

� Vapour pressures antimony

-40

-30

-20

-10

0

10 pSb pSb2 pSb4

lnp(

Sbx

, Atm

)

42 SbSbtotalSb, ppp +=2p

Results NiResults Ni--SbSb--SnSn System System evaluationevaluation

)(

)()(

SoSb

SSbSSb Tp

TpTa =

0.0 0.4 0.8 1.2 1.6 2.0-50

-40lnp(

Sbx

, Atm

)

1000/T, K 4

2

Sb

2Sb

p

pK =

4 0Sb

SbSb

4

4

p

pa =

TOFA-2010 Sept. 12-16

Results NiResults Ni--SnSn--Sb Sb SystemSystem

Partial enthalpies of antimony can be obtained from the slope of ln(aSb) vs. 1/T plot at a fixed Composition.

SbH∆

Then the activities are converted into to one common temperature

TOFA-2010 Sept. 12-16

Results Results NiNi33SnSn22--SbSb SystemSystem

-0.6

-0.4

-0.2

0.0

xSb=0.55 xSb=0.60 x Sb=0.65 xSb=0.70 XSb=0.75 xSb=0.80

Ln(a

, Sb)

Composition(At % Sb)

Partial Molar Enthalpy of Sb

(kJ/Mol)

0.55 8.97

0.60 7.31

0.65 5.35

( ) R

H

T

a PP ∆=∂∂

1

ln

Natural logarithm of Sb activity vs. reciprocal temperature

for selected compositions in the liquid phase as an

example.

7.0 7.5 8.0 8.5 9.0 9.5 10.0-0.8

10000/T, K

0.70 3.07

0.75 1.53

0.80 1.03

Similar results were also obtained for Ni3SnAnd Ni3Sn4 alloys

TOFA-2010 Sept. 12-16

Integrated Gibbs-Helmholtz Equation:

−∆=−

2121

11)(ln)(ln

TTR

HTaTa P

PP

Natural logarithm of the antimony activity as a function of composition for Ni3Sn2 in the liquid phase at 1150 K; standard state: liquid Sb.

TOFA-2010 Sept. 12-16

Summary• The thermal analysis Sn-rich corner in the

Ni-Sb-Sn System was carried out

• The diagram for 80 and 85 at Sb% isopleth was delin eated

• The Scheil Diagram and the liquidus projections for Sn-rich corner of Ni -Sb-Sn system were determined.corner of Ni -Sb-Sn system were determined.

• The phase diagram for ternary Ni-Sn-Sn system at 90 0 °C is presented

• Thermochemical data on Ni-Sb-Sn system is being obtained by isopiestic method

TOFA-2010 Sept. 12-16

Acknowledgements

� This research is part of the European Research

Actions COST 531 and COST MP0602

�Financial Support:

Marie Curie Foundation Marie Curie Foundation

(FP7-PEOPLE-IIF-2008, Project No. 234920)

and the European Union (COST) for networking.

TOFA-2010 Sept. 12-16

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