Effect of process-induced voids on isothermal fatigue resistance of CSP lead-free solder joints

Yu, Qiang; Shibutani, Tadahiro; Kim, Do Seop; Kobayashi, Yusuke; Yang, Jidong; Shiratori, Masaki

doi:10.1016/j.microrel.2007.08.008

Cited by 38 publications

(4 citation statements)

References 19 publications

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“…As a result, the macrovoids block the linear path of the heat flux thus leading to reduction in the thermal conductivity of that area of the STIM layer. This is the evidence that supports findings by Yu et al [24] which suggests that macrovoids reduce significantly the fatigue resistance of the voids. The microvoids of Figure 19 did not seem to cause an appreciable change in the heat flux hence the thermal resistance will be quite low in such regions.…”

Section: Effect Of Surface/edge Voidssupporting

confidence: 92%

“…The impact of voids in thermo-mechanical reliability of solder joints has been studied and reported extensively. Yu et al [24] observed that voids influence the thermal fatigue resistance of CSP solder joints. The authors observed that small voids (i.e microvoids) have no apparent effect on fatigue life but when the voids are big, usually about 30% of the solder size, and located along the crack path, they adversely affect the fatigue resistance.…”

Section: Introductionmentioning

confidence: 99%

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A computational investigation of the effect of three-dimensional void morphology on the thermal resistance of solder thermal interface materials

Okereke

2018

Applied Thermal Engineering

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Process-induced solder voids have three-dimensional shapes and show spatially random distribution with polydisperse geometric dimensions. There exists no analytical formulation of thermal resistances which incorporates void shapes, distribution and polydispersity variables. This paper uses finite element methods to investigate the effect of realistic void morphology on the thermal resistance of solder thermal interface materials (STIMs). The study has developed two computationally efficient methods for generating voids that show the features of real voids. Cylindrical and spherical void morphologies have been studied. The study is the first attempt, in literature, of characterizing the holistic effects of such realistic three-dimensional void morphologies on the thermal resistance of STIM layers. We have shown a qualitative agreement between our results and simplistic analytical predictions. However, the influence of void shapes, distribution and polydispersity have been shown to contribute to increased thermal resistances. The findings should provide significant insight to electrical/electronics engineers, micro-electronics chips manufacturers and academic research groups working on thermodynamics design of chip scale package (CSP) devices. It is also a framework for investigating objectively, the consequence of voids on the thermomechanical response of solder joints.

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Section: Effect Of Surface/edge Voidssupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

A computational investigation of the effect of three-dimensional void morphology on the thermal resistance of solder thermal interface materials

Okereke

2018

Applied Thermal Engineering

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“…9c and d it was concluded that with continued growth of these cracks, their locations constantly became closer to each other, which further increased the accumulated strain and promoted the interlinkage, thus accelerating the creep life failure. 40,41 Comparison of Figs. 8 and 9 reveals that the size of the interfacial cracks is smaller than that of the internal cracks.…”

Section: Cross-sectional Cracking Patternsmentioning

confidence: 99%

Three-Dimensional Visualization of the Crack-Growth Behavior of Nano-Silver Joints During Shear Creep

Tan

Chen

et al. 2014

Journal of Elec Materi

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Evolution of creep damage in nano-silver sintered lap shear joints was investigated at 325°C. Non-destructive x-ray three-dimensional (3D) visualization clearly revealed the crack-growth behavior of the joint; this could be divided into three stages. In the initial stage, little development of cracks occurred. In the second stage, cracks propagated at a consistent rate. In the final stage, rapid extension of the cracks led directly to fracture of the joint. Three-dimensional volume-rendered images and fractographic analysis showed that the growth of macroscopic initial cracks at the interfaces dominated the creep fracture process. Initial failure of nano-silver sintered lap shear joints often occurred at interfacial nano-silver paste layers. Both the size and position of the initial interfacial cracks had significant effects on the final creep failure of the joints, and higher stresses led to greater porosity and earlier failure.

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“…There are many factors affecting the reliability of solder joints, one of the common defects like bubbles have a great influence on reliability. Some researches like aging process, crack initiation, mechanical property and so on have confirmed that bubbles decrease the reliability of devices in service [4]. During solder processing, the gases and vapors released from flux melting will trape inside the solder alloy, thus being the possible source of bubbles.…”

Section: Introductionmentioning

confidence: 99%

In situ study on growth behavior of interfacial bubbles and its size effect on Sn-0.7cu/Cu interfacial reaction

Sun

Kunwar

et al. 2014

2014 Joint IEEE International Symposium on the Applications of Ferroelectric, International Workshop on Acoustic Transduction M

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With the advent of lead-free soldering electronic packaging industry, there are growing concerns regarding the problems of voids in lead-free solder joints. Many researchers are eager to understand the growth,evolution and control factors of bubbles. Due to the restrictions in test conditions imposed by high temperature and opacity of soldering, one cannot directly observe and analyze the behaviour of bubbles. Moreover, bubble evolution and surface reaction effects go hand in hand with each other during soldering; so the latter should be interfering the pattern of the former and vice-versa. In this study, the growth behavior of interfacial bubbles and the effect of bubbles on interfacial reaction during a soldering process were in situ studied by the synchrotron radiation real-time imaging technology. In the scanning electron microscope, we can observe the bubbles size and its impact on the scope of IMC at Sn-0.7Cu soldering on 250 . We found that bubbles effecting surface reaction have a the critical value and there is differentiate between different size of bubbles and its area of influence, the larger of bubbles, the greater effecting area. The closer to the bottom of the bubble, the less the Cu substrate dissolved. The effect of bubble on the IMC growth around the bubble was small, and the average IMC size decreased gradually with the increase of the distance and stabilized finally.

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Effect of process-induced voids on isothermal fatigue resistance of CSP lead-free solder joints

Cited by 38 publications

References 19 publications

A computational investigation of the effect of three-dimensional void morphology on the thermal resistance of solder thermal interface materials

A computational investigation of the effect of three-dimensional void morphology on the thermal resistance of solder thermal interface materials

Three-Dimensional Visualization of the Crack-Growth Behavior of Nano-Silver Joints During Shear Creep

In situ study on growth behavior of interfacial bubbles and its size effect on Sn-0.7cu/Cu interfacial reaction

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