Interfacial microstructures and kinetics of Au/SnAgCu

Lee, Teck Kheng; Zhang, Sam; Wong, Chee Cheong; Tan, A.C.; Hadikusuma, Davin

doi:10.1016/j.tsf.2005.09.112

Cited by 33 publications

(10 citation statements)

References 12 publications

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“…Although the melting point of Au (1064 • C) is much higher than the temperature of molten solder, atomic diffusion and the consequent formation of equilibrium phases results in its dissolution. The entire plating of ∼2 m thickness was dissolved and given the short time span it is believed that Au diffused within the solder with a diffusion rate of about 2.5 × 10 −3 m/s, which are in agreement with values reported by Lee et al [13]. It should be noted that Ag and Cu went undetected in the Auger scan, and it will be first assumed that Ag and Cu do not play major roles on the diffusion and phase formation.…”

Section: Resultssupporting

confidence: 90%

Interfacial intermetallic phases and nanoeutectic in rapidly quenched Sn–Ag–Cu on Au under bump metallization

Bali

Fleury

Han

et al. 2008

Journal of Alloys and Compounds

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Section: Resultssupporting

confidence: 90%

Interfacial intermetallic phases and nanoeutectic in rapidly quenched Sn–Ag–Cu on Au under bump metallization

Bali

Fleury

Han

et al. 2008

Journal of Alloys and Compounds

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“…Additionally, the high concentration of Sn in Pb-free solder induces more excessive growth of IMCs than for eutectic Sn-Pb solder. 7 Extensive IMC growth and Kirkendall void formation, which results from the difference in the intrinsic diffusivities of Cu and Sn, in solder joints can severely deteriorate the mechanical strength of the joints. [8][9][10] The mechanical reliability of solder joints is sensitive to the solder reaction and the microstructure of the solder.…”

Section: Introductionmentioning

confidence: 99%

Temperature Effect on Intermetallic Compound Growth Kinetics of Cu Pillar/Sn Bumps

Lim

Kim

Lee³

et al. 2009

Journal of Elec Materi

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The in situ intermetallic compound (IMC) growth in Cu pillar/Sn bumps was investigated by isothermal annealing at 120°C, 150°C, and 180°C using an in situ scanning electron microscope. Only the Cu 6 Sn 5 phase formed at the interface between the Cu pillar and Sn during the reflow process. The Cu 3 Sn phase formed and grew at the interfaces between the Cu pillar and Cu 6 Sn 5 with increased annealing time. Total (Cu 6 Sn 5 + Cu 3 Sn) IMC thickness increased linearly with the square root of annealing time. The growth slopes of total IMC decreased after 240 h at 150°C and 60 h at 180°C, due to the fact that the Cu 6 Sn 5 phase transforms to the Cu 3 Sn phase when all of the remaining Sn phase in the Cu pillar bump is completely exhausted. The complete consumption time of the Sn phase at 180°C was shorter than that at 150°C. The apparent activation energy for total IMC growth was determined to be 0.57 eV.

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“…When annealed at higher temperature (543 K), Sn and AuSn 4 melt and accelerate the eutectic reaction between Au and Sn, forming a eutectic structure of Au-Sn solder. It is difficult to quantify the growth of the Au-Sn IMC layers in solid-liquid interdiffusion, as the solid-liquid interdiffusion is four orders of magnitude faster than solid diffusion [15][16]. Therefore, as the Au/Sn/Au/Sn/Au/Sn/Au couple is annealed at 543 K for 6 h, the Au and Sn react completely to form a brittle Au-Sn solder with a eutectic structure.…”

Section: Growth Behavior Of Imc Layersmentioning

confidence: 99%

Microstructural evolution of Au-Sn solder prepared by laminate rolling during annealing process

et al. 2011

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The microstructural evolution and interfacial reaction of the Au/Sn/Au/Sn/Au/Sn/Au couples were investigated during annealing at 453, 523, and 543 K for up to 240 h. The Au/Sn combination formed a rapid diffusion system. Even in rolled Au-Sn solder, three phases, such as AuSn, AuSn 2 , and AuSn 4 , were formed. After initial annealing at 453 K, the diffusion layers of AuSn, AuSn 2 , and AuSn 4 , which were formed after rolling, expanded gradually and then fully transformed into ζ phase (containing Sn from 10% to 18.5%, mole fraction) and δ (AuSn) phase. As a whole, the microstructure of the couple was stable during annealing at 453 K. The solid-state interfacial reaction was much faster at 523 K than at 453 K. After annealing at 523 K for 6 h, the AuSn, AuSn 2 , and AuSn 4 were fully transformed into the ζ phase and δ phase (AuSn). In spite of the prolonged annealing time for up to 240 h, no significant change of the interfacial microstructure occurred, and the microstructure of the couple was stable during annealing at 523 K. When annealing at 543 K, however, the interfacial of Au/Sn was transformed into solid-liquid state, and the whole couple formed a eutectic structure rapidly, causing the solder to be brittle. The study results clearly demonstrate that the service temperature of the Au-Sn solder should be lower than 543 K.

show abstract

Interfacial microstructures and kinetics of Au/SnAgCu

Cited by 33 publications

References 12 publications

Interfacial intermetallic phases and nanoeutectic in rapidly quenched Sn–Ag–Cu on Au under bump metallization

Interfacial intermetallic phases and nanoeutectic in rapidly quenched Sn–Ag–Cu on Au under bump metallization

Temperature Effect on Intermetallic Compound Growth Kinetics of Cu Pillar/Sn Bumps

Microstructural evolution of Au-Sn solder prepared by laminate rolling during annealing process

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