The Creep-Fatigue Interaction in Solders and Solder Joints

1990 ◽  
Vol 112 (2) ◽  
pp. 100-103 ◽  
Author(s):  
D. S. Stone
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Solder Joints ◽  
Fatigue Cracks ◽  
Solution Concentration ◽  
Grain Boundary Sliding ◽  
Cycle Frequency ◽  
Low Frequencies ◽  
Creep Fatigue ◽  
Failure Life

Two models are proposed for relating the metallurgy of the solder to the growth of fatigue cracks through solder joints. These models illustrate how different aspects of the creep behavior can contribute to the so-called “creep-fatigue interaction”. The first model treats fatigue crack growth through the solder, far from the interface between solder and substrate. Either an intragranular or intergranular path may be taken depending upon conditions of loading. Intragranular fatigue dominates when the cycle frequency is high, in which case failure life is governed by the Coffin-Manson law. Intergranular failure occurs at low frequencies because grain boundary sliding at low frequencies allows the grain boundaries to become exposed to the atmosphere, which in turn causes oxidation. This model predicts the effects of frequency, strain amplitude, and grain size on fatigue life. In the second model, the fatigue crack travels within the interface region between solder and substrate. Here, the strain introduced in the solder joint during fatigue is not relevant; instead, the stress transferred to the interface is more important. The second model considers the effect of solid solution concentration on fatigue life. The predictions of both models agree reasonably well with published fatigue data from solders and solder joints.

scholarly journals Structural and mechanical defects of materials of offshore and onshore main gas pipelines after long-term operation

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Pavlo Maruschak ◽  
Sergey Panin ◽  
Iryna Danyliuk ◽  
Lyubomyr Poberezhnyi ◽  
Taras Pyrig ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Quantitative Analysis ◽  
Stress Concentration ◽  
Cyclic Loading ◽  
Fatigue Cracks ◽  
Preliminary Deformation ◽  
Term Operation ◽  
Steel Pipes

AbstractThe study has established the main regularities of a fatigue failure of offshore gas steel pipes installed using S-lay and J-lay methods.We have numerically analyzed the influence of preliminary deformation on the fatigue life of 09Mn2Si steel at different amplitudes of cyclic loading. The results have revealed the regularities of formation and development of a fatigue crack in 17Mn1Si steel after 40 years of underground operation. The quantitative analysis describes the regularities of occurrence and growth of fatigue cracks in the presence of a stress concentration.

Nondestructive Observation of Thermal Fatigue Crack Propagation in FBGA and Die Attached Solder Joints by Synchrotron Radiation X-Ray Laminography

2015 ◽  
Author(s):  
Hiroyuki Tsuritani ◽  
Toshihiko Sayama ◽  
Yoshiyuki Okamoto ◽  
Takeshi Takayanagi ◽  
Masato Hoshino ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Synchrotron Radiation ◽  
Crack Propagation ◽  
Thermal Fatigue ◽  
Solder Joints ◽  
Fatigue Cracks ◽  
Three Dimensional ◽  
X Ray ◽  
Micro Cracks ◽  
Solder Bumps

The reliability of solder joints on printed circuit boards (PCBs) is significantly affected by thermal fatigue processes due to downsizing and high density packaging in electronic components. Accordingly, there is a strong desire in related industries for development of a new nondestructive inspection technology to detect fatigue cracks appearing in these joints. The authors have applied the SP-μCT, a synchrotron radiation X-ray microtomography system, to the nondestructive observation of such cracks. However, for planar objects such as PCB substrates, reconstruction of CT images is difficult due to insufficient X-ray transmission along the parallel axis of the substrate. In order to solve this problem, a synchrotron radiation X-ray laminography system was developed to overcome the size limits of such specimens. In this work, this system was applied to the three-dimensional, nondestructive observation of thermal fatigue cracks in solder joints, for which X-ray CT inspection has been extremely difficult. The observed specimens included two typical joint structures formed using Sn-3.0Ag-0.5Cu solder: (1) a fine pitch ball grid array (FBGA) joint specimen in which an LSI package is connected to a substrate by solder bumps 360 μm in diameter, and (2) a die-attached specimen in which a 3 mm square ceramic chip is mounted on a substrate. The optical system developed for use in X-ray laminography was constructed to provide a rotation axis with a 30° tilt from the right angle to the X-ray beam, and to obtain X-ray projection images via the beam monitor. The same solder joints were observed successively using the laminography system at beamline BL20XU at SPring-8, the largest synchrotron radiation facility in Japan. In the FBGA type specimen, fatigue cracks were clearly observed to appear at the periphery of the joint interface, and to propagate gradually to the inner regions of the solder bumps as thermal cycling proceeded. In contrast, in the die-attached joint specimen, micro-cracks were observed to appear and propagate through the thin solder layer. An important observation was that these micro-cracks become interconnected prior to propagation of the main fatigue crack. The fatigue crack propagation lifetime was also estimated in both specimens by measuring the crack surface area and calculating the average crack propagation rate through the three-dimensional images. Consequently, the sectional images obtained by the laminography system clearly show the process of crack propagation due to thermal cyclic loading.

Effect of Micro Structure on Fatigue Characteristics of Lead Free Solder Joints

2011 ◽  
Author(s):  
Takahiro Akutsu ◽  
Qiang Yu
Keyword(s):  
Grain Size ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Solder Joint ◽  
Crack Propagation ◽  
Solder Joints ◽  
Lead Free ◽  
Lead Free Solder ◽  
Micro Structure ◽  
Free Solder

This paper presents the influence of the micro structure on the crack propagation in lead free solder joint. The author’s group have studied the Manson-Coffin’s law for lead free solder joint by using the isothermal fatigue test and FEM analytical approaches to establish the practicable evaluation of thermal fatigue life of solder joints, for example, for the Sn-Cu-Ni solder, because this solder is attracted from the aspect of the decrease of solder leach in the flow process and material cost. However, even if the same loading is given to the solder joints of BGA test piece, there was a large dispersion in the fatigue life. Even though the effect of the shape difference has been considered, the range of the dispersion could not been explained sufficiently. In the study, the fatigue crack propagation modes in the solder joints were investigated, and an internal fatigue crack mode and an interfacial fatigue crack mode were confirmed. And the tendency of a shorter on fatigue life in the interfacial fatigue mode was confirmed. To clarify the mechanism of these fatigue crack modes, the crystal grain size in the solder joints was investigated before the fatigue test and also after the test. Furthermore, the verification of the mechanism using FEM models considering the crystal grain size was carried out. First of all, each element in FEM models matching to the average crystal grain size was made. Second, the inelastic strain ranges in each FEM models were studied. As a result, it was shown that the influence of the crude density of the crystal grain to the fatigue crack progress can be evaluated. In addition, the micro structure of the solder joint of large-scale electronic devices is observed, and FEM model was made based on the observation result. As a result, it was shown that the influence of the directionality with the crystal grain to the fatigue crack progress can be evaluated.

Fatigue crack growth behavior of rib-to-deck double-sided welded joints of orthotropic steel decks

2020 ◽  
pp. 136943322096175
Author(s):  
Yang Liu ◽  
Fanghuai Chen ◽  
Da Wang ◽  
Naiwei Lu
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Growth ◽  
Welded Joints ◽  
Mixed Mode ◽  
Fatigue Cracks ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Fatigue Crack Growth Behavior ◽  
Orthotropic Steel Decks

Innovative double-sided welding is expected to improve the fatigue resistance of rib-to-deck welded joints of orthotropic steel decks (OSDs). Welding crack-like defects are the crucial issue affecting the fatigue performance of rib-to-deck double-sided welded joints. This study presents a numerical simulation of three-dimensional (3D) mixed mode fatigue crack growth behavior of rib-to-deck double-sided welded joints of OSDs. Maximum tensile stress theory and equivalent stress intensity factor (SIF) were used to simulate mixed mode fatigue cracks growth. The Paris law model was employed to predict the fatigue life. Fatigue cracks of rib-to-deck double-sided welded joints were characterized by the presence of mixed mode cracks of modes I (open), mode II (shear), and mode III (tear), which was dominated by mode I. The equivalent SIF was found to be complex at the growth stage with the maximum value at the two ends of the crack front and the minimum value at the midpoint of the crack front. The crack shape became flatter in the later phase of the crack growth. The fatigue crack surface underwent deflections during crack growth, making the final crack shape exhibiting the characteristic of a spatial curved surface. The initial crack geometry showed a significant impact on the fatigue life.

scholarly journals Experimental and Numerical Investigations of Fretting Fatigue Behavior for Steel Q235 Single-Lap Bolted Joints

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Yazhou Xu ◽  
Zhen Sun ◽  
Yuqing Zhang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Failure Mode ◽  
Contact Stress ◽  
Fatigue Cracks ◽  
Fretting Fatigue ◽  
Bolted Joints ◽  
Normal Contact Stress ◽  
Normal Contact

This work aims to investigate the fretting fatigue life and failure mode of steel Q235B plates in single-lap bolted joints. Ten specimens were prepared and tested to fit theS-Ncurve. SEM (scanning electron microscope) was then employed to observe fatigue crack surfaces and identify crack initiation, crack propagation, and transient fracture zones. Moreover, a FEM model was established to simulate the stress and displacement fields. The normal contact stress, tangential contact stress, and relative slipping displacement at the critical fretting zone were used to calculate FFD values and assess fretting fatigue crack initiation sites, which were in good agreement with SEM observations. Experimental results confirmed the fretting fatigue failure mode for these specimens. It was found that the crack initiation resulted from wear regions at the contact surfaces between plates, and fretting fatigue cracks occurred at a certain distance away from hole edges. The proposed FFD-Nrelationship is an alternative approach to evaluate fretting fatigue life of steel plates in bolted joints.

Assessment of Failure Life Evaluation Methods for Structural Discontinuities with Fatigue and Creep-Fatigue Tests on Multi-Perforated Plate Made of Mod.9Cr-1Mo Steel

2021 ◽  
Author(s):  
Masanori Ando ◽  
Yuichi Hirose ◽  
Takano Masahito
Keyword(s):  
Fatigue Life ◽  
Perforated Plate ◽  
Estimation Method ◽  
Evaluation Methods ◽  
Fatigue Tests ◽  
Reduction Factor ◽  
Life Evaluation ◽  
Creep Fatigue ◽  
Number Of Cycles ◽  
Failure Life

Abstract This study compares and assesses the different fatgue and creep-fatigue life eveluation methods by performing tests of perforated plate made of Mod.9Cr-1Mo steel. Multi-perforated plate was subjected to mechanical cyclic loading at 550°C, and crack initiation and propagation on the surfaces of the holes were observed. A series of finite element analyses (FEA) were carried out to predict the number of cycles to failure by the several failure life evaluation methods, and these predictions were then compared with the test results. Several types of evaluation methods that use the elastic FEA were applied, namely the stress redistribution locus (SRL) method, simple elastic follow-up method. In addition to these, evaluation was also carried out using the results of inelastic FEA to compare these elastic FEA based estimation method. The comparisons indicate that, for all conditions tested, the SRL method provided a rational prediction of the fatigue and creep-fatigue life when ? = 1.6 was applied, where ? = 1.6 is the recommended reduction factor for this method in general use. A comparison of the SRL method and the results of the inelastic FEA indicated that the applicability of the value of factor ? in the SRL method depends on the elastic region remaining in the cross-section including the evaluated point and the spread in the plastically deformed region in the specimen.

A Framework of Integrated Creep-Fatigue Modeling

2009 ◽  
Author(s):  
X. Wu ◽  
S. Yandt ◽  
Z. Zhang
Keyword(s):  
Fatigue Crack ◽  
Polycrystalline Material ◽  
Creep Damage ◽  
Inelastic Strain ◽  
Grain Boundary Sliding ◽  
Deformation Mechanisms ◽  
Final Fracture ◽  
Creep Fatigue ◽  
Boundary Sliding ◽  
Life Consumption

A framework of integrated creep-fatigue (ICF) modeling is proposed based on the deformation decomposition rule that the total inelastic strain (in a polycrystalline material) consists of intragranular deformation (ID) and grain boundary sliding (GBS). With consideration of the respective deformation mechanisms, the resulting constitutive laws are given in 3D tensor forms such that fatigue damage (ID) and creep damage (GBS) are represented in different strain spaces, respectively. Then, the creep-fatigue life consumption can be evaluated using a physics-based formula that captures the intricate interaction between a propagating fatigue crack and distributed creep damage, leading to final fracture.

Effect of high-frequency PCB laminate on thermal cycling behavior of electronic packaging structures

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Lijuan Huang ◽  
Zhenghu Zhu ◽  
Hiarui Wu ◽  
Xu Long
Keyword(s):  
Fatigue Life ◽  
Thermal Cycling ◽  
Electronic Packaging ◽  
High Frequency ◽  
Solder Joints ◽  
Fatigue Cracks ◽  
Cyclic Stress ◽  
Content Type ◽  
Stress States ◽  
Packaging Structure

PurposeAs the solution to improve fatigue life and mechanical reliability of packaging structure, the material selection in PCB stack-up and partitioning design on PCB to eliminate the electromagnetic interference by keeping all circuit functions separate are suggested to be optimized from the mechanical stress point of view.Design/methodology/approachThe present paper investigated the effect of RO4350B and RT5880 printed circuit board (PCB) laminates on fatigue life of the QFN (quad flat no-lead) packaging structure for high-frequency applications. During accelerated thermal cycling between −50 °C and 100 °C, the mismatched coefficients of thermal expansion (CTE) between packaging and PCB materials, initial PCB warping deformation and locally concentrated stress states significantly affected the fatigue life of the packaging structure. The intermetallics layer and mechanical strength of solder joints were examined to ensure the satisfactorily soldering quality prior to the thermal cycling process. The failure mechanism was investigated by the metallographic observations using a scanning electron microscope.FindingsTypical fatigue behavior was revealed by grain coarsening due to cyclic stress, while at critical locations of packaging structures, the crack propagations were confirmed to be accompanied with coarsened grains by dye penetration tests. It is confirmed that the cyclic stress induced fatigue deformation is dominant in the deformation history of both PCB laminates. Due to the greater CTE differences in the RT5880 PCB laminate with those of the packaging materials, the thermally induced strains among different layered materials were more mismatched and led to the initiation and propagation of fatigue cracks in solder joints subjected to more severe stress states.Originality/valueIn addition to the electrical insulation and thermal dissipation, electronic packaging structures play a key role in mechanical connections between IC chips and PCB.

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