Development of gold based solder candidates for flip chip assembly

Chidambaram, Vivek; Hald, John; Hattel, Jesper Henri

doi:10.1016/j.microrel.2008.12.012

Cited by 29 publications

(8 citation statements)

References 9 publications

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“…Possible candidates are Zn-based alloys (Zn-Al, Zn-Sn) [1,2], Bi-based alloys (Bi-Ag) [3], Sn-Sb based alloys [4], and especially Aubased alloys [5][6][7][8]. For example, Au-Si, Au-Sb, and AuGe alloy systems are all simple eutectic systems with low eutectic temperatures between 280 and 365°C [9]. In addition to the low melting point, Au-based alloys also possess good thermal and electrical conductivity, excellent resistance to corrosion, high mechanical properties, etc.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation and thermodynamic modeling of the Au–Ge–Ni system

et al. 2012

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Phase equilibria in the Au-Ge-Ni ternary system were studied by means of scanning electron microscopy, electron probe microanalysis, X-ray diffraction, and differential scanning calorimetry. The phase relations in the solid state at 600°C as well as a vertical section at Au 72 Ge 28 -Ni were established. No ternary compound was found at 600°C. On the basis of the experimental phase equilibria data, a thermodynamic model of the Au-Ge-Ni ternary system was developed using the CALPHAD method. Thermodynamically calculated phase diagrams are shown at 600°C, in two vertical sections and the liquidus projection. Reasonable agreement between the calculations and the experimental results was achieved.

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Section: Introductionmentioning

confidence: 99%

Experimental investigation and thermodynamic modeling of the Au–Ge–Ni system

et al. 2012

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“…A thin, continuous and uniform IMC layer is an essential requirement for good bonding. However, the formation of thick IMCs may degrade the reliability of the solder joint due to their inherent brittle nature and their tendency to generate structural defects [4] Therefore, the interfacial reactions of Au-Ge and Au-Si eutectic alloys with two different UBMs, i.e., Cu/Au and ENIG have been studied. Moreover, the impacts of thermal aging at 300°C up to 500 h have also been analyzed.…”

Section: Interfacial Reactionmentioning

confidence: 99%

High reliability gold based solder alloys for micro-electronics packaging for high temperature applications

Chidambaram

Yeung

Gao

2012

2012 19th IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits

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The performance of the Au-Ge eutectic solder alloy and the Au-Si eutectic solder alloy at 300°C up to 500 h has been extensively reported. Coarsening of the dispersed (Ge) phase as well as the dissolution of the hard (Ge) phase into the soft (Au) matrix is observed during thermal aging. Shear testing and nano-indentation confirmed the loss of strength of the Au-Ge bulk solder during thermal aging at 300°C. However, a fraction of the lost strength was recovered during the final stages of thermal aging at 300°C for 500 h. The coarsening effect was more pre-dominant in the Au-Si eutectic alloy. The pace at which the Au-Si eutectic alloy loses its strength during aging at 300°C is significantly higher, when compared to Au-Ge eutectic alloy. The possibility of averting the grain coarsening in Au-Ge eutectic solder alloy by micro-alloying has also been explored. Among the low melting point metals, Sn has been identified as a potential candidate, since it can dissolve in the (Ge) phase. The reliability of the solder joint is also influenced by the intermetallic compounds (IMC) formed between the bulk solder and the solder wettable layer of the under-bump metallization (UBM). Hence, the interfacial reactions between the Au-Ge and Au-Si eutectic solder alloys and the electroless nickel immersion gold (ENIG) andCu/Au UBMs have also been extensively studied. ENIG has been identified as a prospective UBM candidate for these eutectic alloys as their consumption during aging and wetting is minimal. Based on the present work's findings, it can be concluded that among the binary eutectic alloys, Au-Ge eutectic alloy is better suited for high-temperature applications.

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“…These ternary combinations were then optimized for a narrow solidification range since a narrow solidification range is commercially preferred for facilitating rapid production, efficient process control, preventing the movement of components during solidification and for minimizing segregation during solidification [4,5]. Phases predicted in the bulk solder for these optimized ternary combinations at 150 and 200 • C are shown in Table 1.…”

Section: Thermodynamic Predictionsmentioning

confidence: 99%

“…Thus, the establishment of high-temperature lead-free solders is an urgent priority in the electronics and automotive industries [3]. The primary indispensable requirement for the high-temperature solder selection is the melting temperature range (270-350 • C) [4].…”

Section: Introductionmentioning

confidence: 99%