Failure Mechanisms and Crack Propagation Paths in Thermally Aged Pb-Free Solder Interconnects

Monlevade, Eduardo Franco de; Peng, Weiqun

doi:10.1007/s11664-006-0062-8

Cited by 26 publications

(17 citation statements)

References 18 publications

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“…However, it is known that these intermetallics are brittle. Excessive and large primary intermetallics may deteriorate the solder joint strength depending on the location [52]. Large primary intermetallics located near the solder joint surface may create a weak point and a crack may be initiated.…”

Section: Fabrication Methods Of Reinforced Soldersmentioning

confidence: 99%

“…In the study of failure mechanisms of solder joints, Wang et al [53] and Monlevade at al. [52] indicate that large intermetallics, which includes the primary and interfacial intermetallic compound layer, could promote crack initiation in solder joints. Xian et al [54] report that primary Cu6Sn5 formation in the bulk solder is shown to be affected by the increasing Cu content of the liquid due to the Cu dissolution, the change in phase equilibria and the degree of undercooling for β-Sn.…”

Section: Fabrication Methods Of Reinforced Soldersmentioning

confidence: 99%

“…Spot analysis was conducted on selected areas of the mapping results. From these results, microwave technology can be a significant assistant in the sintering process since heat is generating within the materials and can produce homogeneous bulk heating 52 rates in small time frames and alter the distribution of elements in comparison to conventional sintering [37,49]. Results of synchrotron micro-XRF on conventional and microwave sintered samples of SnCu-Ni with TiO2 were further analyzed using TEM.…”

Section: Microstructure Characterizationmentioning

confidence: 99%

“…Different lattice planes were observed for both Sn and nano crystals in the HRTEM images. It is believed that Schottky disorder could happen to TiO2 at <580 ºC where pairs of Ti ion vacancy and oxide ion vacancy are formed and that this could be accelerated by rapid microwave heating [52]. In addition, with the interaction of multiple valence states of Sn and…”

Section: Microstructure Characterizationmentioning

confidence: 99%

“…Ti may result in the possibility of substitution between Sn and Ti [52]. and conventionally sintered Sn-Cu-Ni with TiO2 ( Figure 10d, 10e and 10f), the binding energy of species on the surface can be evaluated.…”

Section: Microstructure Characterizationmentioning

confidence: 99%

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Microstructure Formation in Reinforced Sn-Cu Lead-free Solder Alloys

Salleh¹,

Anuar²

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Electronics manufacturers are pushing the limits in reducing the physical size of circuitry while simultaneously increasing the number of transistors to satisfy Moore's Law [1]. This includes investing in new materials, and configuring new ways to manufacture complex 3D (three dimensional) electronic packaging [1]. One key requirement of new materials and techniques is ensuring the high reliability of the resultant products in various challenging operating environments including thermal and mechanical extremes [2][3][4]. A viable method to enhance the properties and performance of a solder joint is by incorporation of reinforcement particles to the solder matrix, either by intrinsic or extrinsic methods. In this thesis a series of Sn-Cu Pb-free solder alloys with extrinsic or intrinsic phase reinforcement were manufactured and the microstructure and soldering behavior were investigated in detail.Additions of extrinsic reinforcement in the form of nano-sized ceramic material were made using a microwave sintering powder metallurgy (PM) method, which is a viable method to improve the mechanical and thermal properties of Pb-free solder materials. In addition, the advanced processing routes ensures a homogenous distributions of reinforcement particles is present. To investigate the performance of the reinforced bulk solders including thermal and mechanical properties and relate this to the microstructure, samples were investigated using techniques such as synchrotron micro-XRF, HRTEM, SEM, XPS, dilatometery, DSC and shear and microhardness testing. A hypothesis of how reinforcement improves solder properties is developed and discussed. Synchrotron X-ray radiography imaging (SXRI) was used to analyse the development of microstructure and the complex interactions occurring in the solders. Based on the properties of the fabricated solder, the microwave sintering PM route was discussed as a promising method for the reinforcement of Pb-free solders.The initial formation of interfacial IMC products was studied in Sn-Cu based solder alloys by in situ experiment techniques such as SXRI and UHV-TEM. The results provide direct experimental evidence of real-time initial Cu6Sn5 layer development during soldering and also the stress creation and release events that arise due to the polymorphic transformations of the Cu6Sn5 phase and the associated volumetric change.ii In addition, the nucleation and growth behavior of primary intermetallics which can be considered an intrinsic reinforcing material in solder joints was studied. Here, the nucleation and growth behavior of primary Cu6Sn5 and β-Sn crystals in some of the most commonly used solder alloys including Sn-0.7Cu and Sn-3.0Ag-0.5Cu is explained. This also includes the effects of Ni additions for refining primary Cu6Sn5 in Sn-Cu solder joints. Using SXRI, observations were made during solder joint solidification, which is difficult using conventional methods. The initial nucleation and solidification kinetics of primary Cu6Sn5 crystals were discussed.The growth of pri...

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Section: Fabrication Methods Of Reinforced Soldersmentioning

confidence: 99%