Ternary Intermetallic Compounds in Au-Sn Soldering Systems Structure and Properties

SUPPLEMENTARY INFORMATION

Ternary intermetallic compounds in Au-Sn soldering systems – structure and properties

(Submitted to Journal of Materials Science)

CAROLA J. MÜLLER,1,2 VOLODYMYR BUSHLYA,3 MASOOMEH GHASEMI,4 SVEN LIDIN,1 MARTIN VALLDOR5,6 and FEIWANG1

1.—Lund University, Centre for Analysis and Synthesis, Box 124, 22100 Lund, Sweden. 2. —E-Mail: 3.—Lund University, Production and Materials Engineering, Box 118, 22100 Lund, Sweden. 4.—Lund University, Solid State Physics, Box 118, 22100 Lund, Sweden. 5.—University Cologne, II. PhysikalischesInstitut, Zülpicher Str. 77, 50937 Cologne, Germany. 6.—Current address: Max-Planck-Institute for Chemical Physics of Solids, Nöthnitzer Str.40, 01187 Dresden, Germany

S1: Powder X-Ray Diffraction

Herein, we would like to present additional figures that support the statements in the paper.

Fig. S1: PXRD patterns for Au3InSn2 after different heat treatments. Notably, the different annealing temperatures do not affect the c/a ratios of the compound. Left: Complete measurements; Right: Selected angular range around the strongest reflection.

Fig. S2: PXRD patterns for samples of different compositions Au:In:Sn. The pattern for AuSn was calculated from the reported crystal structure by Jan and coworkers [13]. The results indicate that there is a continuous solid solution of In in the binary compound AuSn. The maximum solid solubility is reached in Au3InSn2. Left: Complete measurements; Right: Selected angular range around the strongest reflection. It is apparent that the lattice parameters are changing anisotropicallybecause there is no constant shift of the positions of the reflections.

Fig. S3: PXRD patterns for samples of different compositions Au:In:Sn. The pattern for Au3In2 was calculated from the reported crystal structure by Schubert and coworkers [19]. It is shown how extra reflections of AuIn and Au3In2 appear in samples whose compositions are on lines from Au3InSn2-AuIn (constant content of Au of 50 at.-%) and Au3InSn2-Au3In2 (increasing Au and In contents). In agreement with Borzone et.al. [15,16], these results indicate that the full solubility of elemental In in the compound AuSn is reached at the composition Au3InSn2.

Fig. S4: PXRD patterns for samples of different compositions Au:In:Sn. It is shown how extra reflections (green arrows) appear on increasing the Au content in the samples, i.e. constant In:Sn ratio. .

Fig. S5: PXRD patterns for samples of different compositions Au:In:Sn. The extra reflections that are very weak in Fig. S4 are in fact two extra phases: Au3In and Au5Sn. .Remarkably, the observed peak positions do neither correspond to the binary compounds Au7In3 nor Au9In4. As a conclusion, thesecompounds do not dissolve any elemental Sn.

Fig. S6: PXRD pattern for a sample of a different composition Au:Sn:Sb, Au3Sn3Sb. The extra reflections correspond to two extra phases: AuSb2 and Au5Sn. This result is indicating that a composition Au6Sn5Sb represents the maximum solid solubility range of Sb in AuSn.

S2: Single Crystal Diffraction

In the following section, details on the results from single crystal X-ray diffraction are given.

Fig. S7: SCXRD: Lattice parameters and c/a ratios of Au3InxSn3-x; for comparison Au6Sn5Sb and Au3In2 are depicted as well [13,19]. The unannealed sample is indicated by the square.

Table S1. Experimental details for SCXRD.

Table S2. Experimental details for SCXRD.

S3: Thermal Analysis

Fig. S8Liquidus projections of the Au-Sb-Sn ternary system are extrapolated from the sub-binaries [55]. The Au6Sn5Sb composition is shown with the red circle. The arrows indicate the crystallization path for this composition. The primary crystallization field is AuSn. Next, the AuSb2 phase precipitates. Finally, Au5Sn forms through a eutectic reaction.

Fig. S9TheAuSn-AuIn vertical section of the Au-In-Sn ternary system is calculated using the assessed parameters by Cacciamani et al. [16]. On cooling from the nominal composition of Au0.5In0.167Sn0.333, the primary crystallization field is AuSn at 749 K.