An Investigation of Diffusion Barrier Characteristics of an Electroless Co(W,P) Layer to Lead-Free SnBi Solder

Pan, Hung-Chun; Hsieh, Tsung−Eong

doi:10.1007/s11664-010-1488-6

Cited by 14 publications

(4 citation statements)

References 19 publications

(25 reference statements)

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“…Compared with Cu, Ag and Ni, Co has relatively high rigidity and stability with temperature [11]. Furthermore, Co is more active than Cu and can form three Co-Sn IMC below 400ºC [12]. For these reasons, Co can be used as a fourth-element to improve the properties of SAC solder.…”

Section: Introductionmentioning

confidence: 99%

Effects of Cobalt Nanoparticles Addition on Shear Strength, Wettability and Interfacial Intermetallic Growth of Sn−3.0Ag−0.5Cu Solder during Thermal Cycling

Liu

Zhao

et al. 2015

MSF

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In the present study, Cobalt nanoparticles were synthesized and mixed with Sn-3.0Ag-0.5Cu solder (SAC305). The effect of 0.05 wt.%, 0.2 wt.%, 0.5 wt.% and 1.0 wt.% Co nanoparticles on the wettability, the shear strength as well as the growth of intermetallic compounds (IMCs) at composite solder/Cu interface during thermal cycling were investigated. Results show that Co nanoparticle addition can considerably improve wettability, increase the shear strength and suppress the growth of interfacial IMCs. The addition amount of Co nanoparticles have the consistent relation with the improvement extent of the wettability, shear strength and the growth rate of interfacial IMCs. Slight addition (0.05 wt.% and 0.2 wt.%) can significantly improve the properties of nanocomposite solder in all the three aspects. However, with excessive addition amount (0.5 wt.% and 1.0 wt.%) of Co nanoparticles, the improvement extent will decline. The Cross-section images of the interface of nanocomposite solder/Cu joint show that Co can form reinforcement particles in the solder and can act as the sacrificial element to substitute Cu to react with Sn. Excessive Co nanoparticles would form large amount of hard and brittle intermetallics which leads to decreasing shear strength of the composite solder.

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Section: Introductionmentioning

confidence: 99%

Effects of Cobalt Nanoparticles Addition on Shear Strength, Wettability and Interfacial Intermetallic Growth of Sn−3.0Ag−0.5Cu Solder during Thermal Cycling

Liu

Zhao

et al. 2015

MSF

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“…Notably, previous study on eutectic SnBi/Co(W,P) system observed the rates of IMC formation and detachment at the P-rich layer are about the same, leading to a nearly constant value of P-rich layer thickness. 25 In contrast, the Prich layer apparently thickened with the increase of aging time in the SAC/Co(W,P) system. This is ascribed to a relatively high Sn content in Pb-free SAC solder which results in more Sn flux into the P-rich layer and thus promotes the IMC formation.…”

Section: Resultsmentioning

confidence: 96%

“…This implies the dominance of diffusion-controlled mechanism in the formation of P-rich layer. 21 Previous studies 10,25 and subsequent TEM analysis indicate the P-rich layer is in fact a mixture of nano-scale IMCs. As a result, the diffusion of Sn through P-rich layer to induce the IMC formation at the front of Co(W,P) should be the controlled process.…”

Section: Resultsmentioning

confidence: 99%

“…6 delineates the amorphous W-rich layer does not inhibit subsequent alloy reactions of Sn and Co to form IMCs. Hence, the barrier capability is correlated to the nature of chemical bonds of the interacting materials 25 rather than the structure amorphism of the barrier layer as proposed by conventional classification scheme. 26 Solid-state aging.-SEM image, EDS line scan profiles, and XTEM micrograph of SAC/poly-Co(W,P) sample subjected to the solid-state aging at 150 • C for 1000 h are separately presented in Figs.…”

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confidence: 99%

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Diffusion Barrier Characteristics of Electroless Co(W,P) Thin Films to Lead-Free SnAgCu Solder

Pan

Hsieh

2011

J. Electrochem. Soc.

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Diffusion barrier and bonding characteristics of amorphous and polycrystalline electroless Co(W,P) layers (α-Co(W,P) and polyCo(W,P)) to SnAgCu (SAC) solder were investigated. In the SAC/α-Co(W,P) sample subjected to liquid-state aging at 250 • C, the spallation of intermetallic compound (IMC) into solder, a nano-crystalline P-rich layer at SAC/Co(W,P) interface, and the recrystallized Co(W,P) containing Co 2 P precipitates were observed. As to the SAC/α-Co(W,P) sample subjected to solid-state aging at 150 • C, a thick IMC layer neighboring to the P-rich layer formed at the solder/Co(W,P) interface. Liquid-state aging resulted in an IMC mixture without spallation whereas solid-state aging induced a layer-like IMC in SAC/poly-Co(W,P) samples. Amorphous W-rich layers were also observed in SAC/poly-Co(W,P) samples and it could not inhibit subsequent alloy reactions in the samples. Analytical results indicated the α-Co(W,P) is a sacrificial-plus stuffed-type barrier whereas the poly-Co(W,P) is mainly a sacrificial barrier. The activation energies of IMC growth were 110.7 and 81.8 kJ/mol for SAC/α-Co(W,P) and SAC/poly-Co(W,P) samples, respectively. High P content in α-Co(W,P) was found to degrade the bonding strength to the solder as revealed by the shear test and the control of P content would be a key issue for electroless plating layer applied to under bump metallurgy as the diffusion barrier.

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Effects of W contents on the solid-state interfacial reactions of Sn/Co-W

et al. 2022

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An Investigation of Diffusion Barrier Characteristics of an Electroless Co(W,P) Layer to Lead-Free SnBi Solder

Cited by 14 publications

References 19 publications

Effects of Cobalt Nanoparticles Addition on Shear Strength, Wettability and Interfacial Intermetallic Growth of Sn−3.0Ag−0.5Cu Solder during Thermal Cycling

Effects of Cobalt Nanoparticles Addition on Shear Strength, Wettability and Interfacial Intermetallic Growth of Sn−3.0Ag−0.5Cu Solder during Thermal Cycling

Diffusion Barrier Characteristics of Electroless Co(W,P) Thin Films to Lead-Free SnAgCu Solder

Effects of W contents on the solid-state interfacial reactions of Sn/Co-W

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