University of Vienna. Department of Inorganic Chemistry / Materials Chemistry

Transcription

1 High temperature lead-free solder: Phase relations in (Cu,Ni)-Sn-Zn R. Divakar, C. Schmetterer, H. Flandorfer, H. Ipser University of Vienna Department of Inorganic Chemistry / Materials Chemistry

2 Content Introduction and Bibliography The binary systems Cu-Sn Ni-Zn Our results on Ni-Sn-Zn Isothermal sections at 700, 800 and 900 C Ternary phases Summary and Outlook

3 Traditional Solders Copper-Gold-Alloys Silver Solders C Hard Soldering Lead-Silver Alloys Indium Alloys Cadmium-Zinc Solders Tin-Lead Alloys Bismuth Alloys Soft Soldering

4 Lead-free Solder materials for low temperature soft soldering are well established: Ag-Sn (e.g., Sn-3.5Ag), Cu-Sn (e.g., Sn-0.7Cu) Ag-Cu-Sn ( SAC, e.g.: Sn-3.7Ag-0.7Cu) In-Sn (e.g., Sn-52In), Ag-In-Sn (e.g., Sn-2.8Ag-20In) Bi-Sn(e.g.: Sn-58Bi) Sn-Zn-X, where X = Cu, Ni, Ag, etc Lead-free Solder materials with T m 230 C up to 350 C are necessary for: power circuits with very high levels of conductivity required automotive industry under bonnet applications - high current and low voltage, high temperatures within the engine area step soldering approach soldering of various levels of the package with different solders of different melting points

5 COST Action MP0602 Advanced Solder Materials for High Temperature Application (HISOLD) Their nature, design, process and control in a multi-scale domain Project leaders: Ales Kroupa and Andy Watson ~ 50 Scientist of 17 countries,

6 The constituent binaries Also PD s of well established binary systems of high technological importance can be improved! We should not trust blindly in compilations and assessments! Cu-Sn very well established, but almost no experimental investigation since 1950ties! Unclear situation at the Cu-rich side concerning β (W-type) γ (BiF 3 -type) transformation Ni-Sn new investigation by Schmetterer et al., published 2007 Cu-Zn new investigation first results Ni-Zn new investigation preliminary results Sn-Zn simple eutectic systems

7 Literature information Some information to the phase relations in the ternary Cu-Sn-Zn is available, literature data to Ni-Sn-Zn are very scarce: Cu-Sn-Zn Several vertical sections, 2 isotherms, liquidus projection mainly based on early investigations from Thermodynamic assessment: T. Jantzen and P.J. Spencer, 1998 Further information to the Cu/Zn corner: C. Vilarinho et al., 2004 Phase equilibria: C.-Y. Chou et al., 2006 Liquidus projection and modeling: Y.-C. Huang et al., 2009 Ni-Sn-Zn Little information to the Sn-Zn rich side: A. Mayer et al., 1968 Phase equilibria (isotherms at 200, 500, 800 C): J. Chang et al; 2010

8 The binary Cu-Zn phase diagram Cu-Zn PD from Massalski s compilation based on the assessment of experimental data by G.V. Raynor, samples have been prepared! Annealed at various temperatures 650, 580, 490, and 400 C XRD, EPMA, DTA Extended solid solubility of Zn in Cu, small amount of Cu in Zn. 5 IMC s: β, δ (W-type), β (CsCl-type), γ (γ-brass type) and ε (Mg-type). Ordering phases in the (Cu) solid solution (S. Müller and A. Zunger, 2001).

9 The binary Ni-Zn phase diagram Ni-Zn PD from Massalski s compilation based on the assessment of experimental data by P. Nash and Y.Y. Pan, 1987 First 4, finally 17 samples at all! Annealed at various temperatures 900, 800, 700, 600, and 400 C XRD, EPMA, DTA Extended solid solubility of Zn in Ni, no significant amount of Ni in Zn. 4 IMC s: β (CsCl-type), β 1 (AuCu-type), γ (γ-brass type) and δ (CoZn 13 -type). Metastable phase formation at Ni-rich side (e.g. Murakami et al., 1984).

10 The binary Ni-Zn phase diagram Ni-rich samples quenched from 900 and 800 C β 1, (Ni) and up to 3 further phases: bcc Ph. (a=5.0431), Ni 3 Zn (AuCu 3 -type), trig. Ph. at. ~ 37 at.% Zn (LaF 3 -type?). long period shear structures Q at the Ni-rich part of the homogeneous range of γ-phase (γ-brass type) described by A.J. Morton (1974) and Nover and Schuster (1980) have been confirmed!

11 Isothermal section of Ni-Sn-Zn 700 C Extended ternary solid solubility of β and β 1 towards Ni-Sn. Pronounced ternary solid solubilities of Ni 3 Zn 14, Ni 3 Sn 2 -HT and Ni 3 Sn-LT. Two ternary compounds, T2 and T3.

12 Isothermal section of Ni-Sn-Zn 800 C Extended ternary solid solubility of β and β 1 towards Ni-Sn. Pronounced ternary solid solubilities of Ni 3 Zn 14, Ni 3 Sn 2 -HT and Ni 3 Sn-LT. Stabilization of Ni 3 Sn-HT (BiF 3 -type) by additions of Zn. At least one ternary compound, T2.

13 Isothermal section of Ni-Sn-Zn 900 C Extended ternary solid solubility of β towards Ni-Sn. Pronounced ternary solid solubilities in Ni 3 Sn 2 -HT and Ni 3 Sn-LT. Stabilization of Ni 3 Sn-HT (BiF 3 -type) by additions of Zn.

14 τ2 Ni 5 Sn 4 Zn Single Crystal XRD oc40, a = Å, b = Å, c = Å, SG = Cmcm Results sent to ICSD, CSD No Analogies to NiAs-type (Ni 3 Sn 2 ), but not a direct superstructure! Isotypic structure Ni 5 Ga 3 Ge 2 described by Bhargava and Schubert, 1974

15 τ3 Ni 2 Sn 2 Zn Single Crystal XRD cp40, a = Å, SG = Pm-3m full occupation in the same cell not possible! Either Sn (40 %) or Zn (60 %), randomly distributed. Results sent to ICSD, CSD No Analogies to γ-brass type and Ru 3 Sn 7 -type structure Very similar structure described as Sn 8.7 (Ni 0.5,Zn 0.4,Cu 0.1 ) 10.4 by Larsson et al., 1994

16 Summary and Outlook A new investigation of Ni-Zn applying various experimental techniques indicates ordering phases in α-(ni) solid solution and the occurrence of an additional compound at ~ 37 at.% Zn with LaF 3 structure. Three isothermal sections of Ni-Sn-Zn at 700, 800, and 900 C have been established based on available literature data and comprehensive experimental work. Two new ternary compounds could be found and their crystal structure solved. Isothermal sections at 1000 and 1100 C are under construction. A liquidus surface projection and various vertical sections will follow. The binary systems Ni-Zn and Cu-Zn are under investigation. The new experimental results promise a improved description of the phase relations. Cu-Sn-Zn is as well under investigation.

17 Acknowledgements Many thanks to: All my colleagues of our department for the excellent collaboration The FWF for financing the projects No. P N19 All the co-operation partner within our COST-Action MP0602 The organizers of this meeting

18 Thank You for Your attention!