1. Phase Equilibria in Ni-P-Sn
C. Schmetterer, J. Vizdal, H. Flandorfer
and H. Ipser
Department of Inorganic Chemistry – Materials Chemistry
University of Vienna
COST 531 Final Meeting, Vienna, May 2007

2. Technological Background
Ni(P) layers as a contact material:
Protective Ni-layer on Cu substrate
in fact: amorphous Ni(P) layers; P is impurity!
Interaction with Sn-based solders?
basic information from phase diagram
ternary phase diagram - and parts of the binaries! - have not yet been investigated

3. Binary Constituents Ni-Sn Phase Diagram
P. Nash and A. Nash, Bull. Alloy Phase Diagrams, 6 (4) (1985) p
C. Schmetterer et al., accepted for publication in Intermetallics

4. Ni-Sn Details
Ni3Sn2 phase transition
Ni3Sn phase transition

5. Ni-P and P-Sn both systems are currently under investigation
experimental + CALPHAD

6. Sample Preparation
from powders of binary end members (e.g. Ni3Sn) and red P, and Sn
many problems!
embrittlement of quartz capsules
explosion of capsules
samples contained in alumina crucibles
alloyed in evacuated quartz tubes employing very slow heating, especially at P > 40 at.%
annealed at 200, 550, 700,
850 and 1050 °C
Ni2P
Ni3Sn2
Ni3Sn

7. Investigations Short Term Scientific Mission host: A. Kodentsov, TUe
In Vienna:
DTA – not yet fully interpreted
XRD – isothermal sections
Short Term Scientific Mission host: A. Kodentsov, TUe
Light microscopy + polarized light
SEM / EDS
diffusion couples

8. Phase relations at 550 °C Ternary phases: Ni2PSn Ni10P3Sn Ni10P3Sn5
T4 – new phase?
Pseudo-binary
System Ni2P – Sn?

9. Phase relations at 700 °C

10. Phase relations at 850 °C

11. Diffusion Couples

12. Diffusion Couples Ni3Sn / Ni2P Annealed at 700 °C in vacuum for 100 h??
Ni3Sn
Ni12P5
100 µm

13. Diffusion Couples Sn / Ni2P Annealed at 200 °C in vacuum for 4 months
Ni2PSn
Ni2P Sn

14. Conclusion and Outlook
Ni-P-Sn:
first information on phase equilibria
diffusion couples
Planned investigations:
continue the phase diagram study
Calorimetry – enthalpy of mixing, enthalpy of formation
CALPHAD study of the system

15. Thank You for Your Attention
Acknowledgements
Thanks to:
K. Richter, U. Saeed
A. Kodentsov (TU Eindhoven, NL)
H. Schmidt (Dep. f. Physical Chemistry)
P. Roussel (Ecole Nationale Superieure de Lille)
A. Leineweber (MPI Stuttgart)
FWF P N11, COST 531, ELFNET
Thank You for Your Attention

16. Ni3Sn Phases – Crystal Structures
Ni3Sn LT: hexagonal – O.K.
Ni3Sn HT:
quenching > 2000°C/sec. :
martensitic transformation to orthohombic bCu3Ti structure
(Pak) Bull. Jpn. Inst. Met., 37(10) (1973) p )
Thermodyn. stable HT phase is cubic with BiF3 type structure
(Schubert; Naturwissenschaften, 43 (1956) p. 248)
only found in powders quenched from 1050 °C
Otherwise massive transformation to LT phase

17. Ni3Sn2 Phase Region
crystallographic relation between NiAs-type HT-phase and the three orthorhombic LT-phases *)
thermal effects detected by heat-flow DSC
transitions involve four invariant reactions
*) incommensurate LT‘ and LT‘‘:
A. Leineweber, Journal of Solid State Chemistry, 159 (2001) p and
Journal of Solid State Chemistry, 177 (2004) p and p