Growth kinetic studies of Cu–Sn intermetallic compound and its effect on shear strength of LCCC SMT solder joints

Chan, Y. C.; So, A.C.K.; Lai, J.K.L.

doi:10.1016/s0921-5107(98)00202-5

Cited by 156 publications

(55 citation statements)

References 12 publications

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“…This differs from earlier published work, which considered IMC formation to be fully diffusion controlled, [18][19][20][21][22] with an analytical solution of the diffusion equation of n = 1/2. However, several studies have presented values of n that vary with temperature.…”

Section: Kinetics Model Estimationcontrasting

confidence: 72%

Optimized Cu-Sn Wafer-Level Bonding Using Intermetallic Phase Characterization

Luu

Duan

Aasmundtveit

et al. 2013

Journal of Elec Materi

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The objective of this study is to optimize the Cu/Sn solid-liquid interdiffusion process for wafer-level bonding applications. To optimize the temperature profile of the bonding process, the formation of intermetallic compounds (IMCs) which takes place during the bonding process needs to be well understood and characterized. In this study, a simulation model for the development of IMCs and the unreacted remaining Sn thickness as a function of the bonding temperature profile was developed. With this accurate simulation model, we are able to predict the parameters which are critical for bonding process optimization. The initial characterization focuses on a kinetics model of the Cu 3 Sn thickness growth and the amount of Sn thickness that reacts with Cu to form IMCs. As-plated Cu/Sn samples were annealed using different temperatures (150°C to 300°C) and durations (0 min to 320 min). The kinetics model is then extracted from the measured thickness of IMCs of the annealed samples.

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Section: Kinetics Model Estimationcontrasting

confidence: 72%

Optimized Cu-Sn Wafer-Level Bonding Using Intermetallic Phase Characterization

Luu

Duan

Aasmundtveit

et al. 2013

Journal of Elec Materi

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“…0.31 and 0.18J/RT (R; universal gas constant, T; absolute temperature) for Cu 6 Sn 5 and Cu 3 Sn in Sn-3.5 mass%Ag/-0.7 mass%Cu, respectively. 16) Considering these chemical analyses, the activation energy and results of other research, [17][18][19][20] the interfacial IMCs from the different solders are believed to be all of the same kind, i.e., Cu 6 Sn 5 . The interfacial IMCs produced by air reflow and by NC plasma reflow for the Sn-37 mass%Pb solder were 51 at%Sn, 49 at%Cu and 52 at%Sn, 48 at%Cu, respectively.…”

Section: Spreading and Bonded Interfacesmentioning

confidence: 99%

Effect of Plasma Cleaning on Fluxless Plasma Soldering of Pb-free Solder Balls on Si-wafer

Moon¹,

Kang²,

Jung³

et al. 2004

Mater. Trans.

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An Ar-10 vol%H 2 plasma was applied as a cleaning medium on UBMs (Under Bump Metallizations) to improve the bondability of solder balls prior to plasma reflow. Each UBM area comprised four layers deposited on a Si-wafer. Sequentially, the deposit comprised 0.4 mm of Al, 4 mm each of Ni and Cu, and 20 nm of Au from bottom to top of the metallization. Two compositions of lead-free solder balls (Sn-3.5 mass%Ag and Sn-3.5 mass%Ag-0.7 mass%Cu) and a lead containing one (Sn-37 mass%Pb) as a reference were selected for the experiment. The solder balls, of 500 mm diameter, were placed on the UBM's and fluxlessly soldered under Ar-10%H 2 plasma (with or without prior plasma cleaning). Additionally, air reflow with flux was also performed for comparison. Experimental results showed that the spreading ratios of the solders by plasma reflow after plasma cleaning were 20-40% higher than those plasma reflowed without cleaning. The shear strengths of the solder balls processed by the plasma-cleaned plasma reflow showed around 58-65 MPa, which is 60-80% and 15-35% higher than that of plasma reflow without plasma cleaning, and that of fluxed air reflow, respectively. From this study, plasma cleaning of UBM's using Ar-10%H 2 gas was shown to be quite effective to improve the bond strength of solder balls.

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“…5,8 The formation of such an IMC layer provides a metallurgical bonding between the solder and the substrate and is indicative of joint adhesion. If overgrown, however, the IMC layer is known to be detrimental to the joint strength due to its brittle nature.…”

Section: Effects Of Microstructural Evolution and Intermetallic Layermentioning

confidence: 99%

“…1 Since solder joints are often subjected to thermal and mechanical loadings during handling and system use, 2 the mechanical properties of solder joints, such as the fatigue and shear strengths and the creep resistance, are the crucial issue for the solder joint reliability as well as the integrity of electronic packaging. [3][4][5][6][7] For the solder joints between a Sn-based solder and a copper substrate, intermetallic compounds (IMCs) such as Cu 6 Sn 5 (h-phase) and Cu 3 Sn (e-phase) form…”

Section: Introductionmentioning

confidence: 99%

Effects of microstructural evolution and intermetallic layer growth on shear strength of ball-grid-array Sn-Cu solder joints

Shin

Baik

Huh

2001

Journal of Elec Materi

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The shear strength of ball-grid-array (BGA) solder joints on Cu bond pads was studied for Sn-Cu solder containing 0, 1.5, and 2.5 wt.% Cu, focusing on the effect of the microstructural changes of the bulk solder and the growth of intermetallic (IMC) layers during soldering at 270∞C and aging at 150∞C. The Cu additions in Sn solder enhanced both the IMC layer growth and the solder/IMC interface roughness during soldering but had insignificant effects during aging. Rapid Cu dissolution from the pad during reflow soldering resulted in a fine dispersion of Cu 6 Sn 5 particles throughout the bulk solder in as-soldered joints even for the case of pure Sn solder, giving rise to a precipitation hardening of the bulk solder. The increased strength of the bulk solder caused the fracture mode of as-soldered joints to shift from the bulk solder to the solder/IMC layer as the IMC layer grew over a critical thickness about 1.2 mm for all solders. The bulk solder strength decreased rapidly as the fine Cu 6 Sn 5 precipitates coarsened during aging. As a consequence, regardless of the IMC layer thickness and the Cu content of the solders, the shear strength of BGA solder joints degraded significantly after 1 day of aging at 150∞C and the shear fracture of aged joints occurred in the bulk solder. This suggests that small additions of Cu in Sn-based solders have an insignificant effect on the shear strength of BGA solder joints, especially during system use at high temperatures.

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Growth kinetic studies of Cu–Sn intermetallic compound and its effect on shear strength of LCCC SMT solder joints

Cited by 156 publications

References 12 publications

Optimized Cu-Sn Wafer-Level Bonding Using Intermetallic Phase Characterization

Optimized Cu-Sn Wafer-Level Bonding Using Intermetallic Phase Characterization

Effect of Plasma Cleaning on Fluxless Plasma Soldering of Pb-free Solder Balls on Si-wafer

Effects of microstructural evolution and intermetallic layer growth on shear strength of ball-grid-array Sn-Cu solder joints

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