Strength of butt and sharp-cornered joints

Reedy,; David, E Myers

doi:10.1016/b978-0-444-51140-9.50032-9

Cited by 4 publications

(1 citation statement)

References 80 publications

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“…Most recently, much attention has been paid to the validation of interface corner failure criterion which is analogous to the LEFM concept [12,[17][18][19][20]. It is well known that when adhesive joint is subjected to a remote uniaxial load, within linear elasticity context, the asymptotic stress field develops at the vicinity of interface corners and exhibits singularity behavior of form σ ≈ Hr -λ [21], where σ is the stress, r is distance from the interface corner, H is the intensity of stress singularity and λ is the order of stress singularity. Instead of the crack, H is associated with the discontinuity at the interface corner.…”

Section: Hc Parameter Based Strength Prediction Of Scarf Jointsmentioning

confidence: 99%

Strength prediction of epoxy adhesively bonded scarf joints of dissimilar adherends

Afendi

Teramoto

Bakri

2011

International Journal of Adhesion and Adhesives

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In this study, strength of epoxy adhesively bonded scarf joints of dissimilar adherends, namely SUS304 stainless steel and YH75 aluminium alloy is examined on several scarf angles and various bond thicknesses under uniaxial tensile loading. Scarf angle, θ = 45º, 60º and 75º are employed. The bond thickness, t between the dissimilar adherends is controlled to be ranged between 0.1 mm and 1.2 mm. Finite element (FE) analysis is also executed to investigate the stress distributions in the adhesive layer of scarf joints by ANSYS 11 code. As the results, the apparent Young's modulus of adhesive layer in scarf joints is found to be 1.5 ~ 5 times higher than those of bulk epoxy adhesive, which has been obtained from tensile tests. For scarf joint strength prediction, the existing failure criteria (i.e. maximum principal stress and Mises equivalent stress) can not satisfactorily estimate the present experimental results. Though the measured stress multiaxiality of scarf joints proportionally increases as the scarf angle increases, the experimental results do not agree with the theoretical values. From analytical solutions, stress singularity exists most pronouncedly at the steel/adhesive interface corner of joint having 45º to 75º scarf angle. The failure surface observations confirm that the failure has always initiated at this apex. This is also in agreement with stress-y distribution obtained within FE analysis. Finally, the strength of scarf joints bonded with brittle adhesive can be best predicted by interface corner toughness, Hc parameter.

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Section: Hc Parameter Based Strength Prediction Of Scarf Jointsmentioning

confidence: 99%

Strength prediction of epoxy adhesively bonded scarf joints of dissimilar adherends

Afendi

Teramoto

Bakri

2011

International Journal of Adhesion and Adhesives

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Application of bimaterial interface corner failure mechanics to silicon/glass anodic bonds

Labossiere

Dunn

Cunningham³

2002

Journal of the Mechanics and Physics of Solids

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Die Cracking at Solder (In60-Pb40) Joints on Brittle (GaAs) Chips: Fracture Correlation Using Critical Bimaterial Interface Corner Stress Intensities

Lee

Dunn

2003

Journal of Electronic Packaging

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We study cracking from the interface of an In60-Pb40 solder joint on a brittle GaAs die when the joint is subjected to a uniform temperature change. Our primary objective is to apply and validate a fracture initiation criterion based on critical values of the stress intensities that arise from an analysis of the asymptotic elastic stress fields at the interface corner. In some regards the approach is similar to interface fracture mechanics; however, it differs in that it is based on a singular field other than that for a crack. We begin by determining the shape that the solder bump will assume after reflow when constrained by a fixed diameter wetting pad on the GaAs. To simplify the interpretation of the results, we focus on a class of solder bumps of various sizes, but with a self-similar shape. The approach, though, can be applied to different size and shape solder bumps. We then compute the asymptotic interface corner fields when the system is subjected to a uniform temperature change. The asymptotic structure (radial and angular dependence) of the elastic fields is computed analytically, and the corresponding stress intensities that describe the scaling of the elastic fields with geometry and loading are computed by axisymmetric finite element analysis. In order to assess the validity of fracture correlation using critical stress intensities, we designed and fabricated a series of test structures consisting of In60-Pb40 solder bumps on a GaAs chip. The test structures were subjected to uniform temperature drops from room temperature to induce cracking at the interface corner. From the tests we determined the relationship between the solder bump size and the temperature change at which cracking occurred. Not unexpectedly, smaller bumps required larger temperature changes to induce cracking. The observed scaling between solder bump size and temperature change is well described by the critical stress intensity failure criterion based on only a single parameter, the critical value of the mode 1 stress intensity, K1crn. Interestingly, this is because over a significant region, the mode 2 and constant terms in the asymptotic expansion cancel each other. This failure criterion provides the necessary machinery to construct failure maps in terms of geometry and thermomechanical loading. We conclude by describing how to apply the approach in more general and more practical settings that are possibly applicable to a wide range of problems in microelectronics, optoelectronics, and microelectromechanical systems packaging.

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Strength of butt and sharp-cornered joints

Cited by 4 publications

References 80 publications

Strength prediction of epoxy adhesively bonded scarf joints of dissimilar adherends

Strength prediction of epoxy adhesively bonded scarf joints of dissimilar adherends

Application of bimaterial interface corner failure mechanics to silicon/glass anodic bonds

Die Cracking at Solder (In60-Pb40) Joints on Brittle (GaAs) Chips: Fracture Correlation Using Critical Bimaterial Interface Corner Stress Intensities

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