Coffin-Manson Model Research Articles

Predicted stresses in a ball-grid-array (BGA)/column-grid-array (CGA) assembly with a low modulus solder at its ends

A simple, easy-to-use and physically meaningful predictive model is suggested for the assessment of thermal stresses in a ball-grid-array or a column-grid-array with a low modulus solder material at the peripheral portions of the assembly. It is shown that the application of such a design can lead to a considerable relief in the interfacial stresses, even to an extent that inelastic strains in the solder joints could be avoided. If this happens, the fatigue strength of the bond and of the assembly as a whole will be improved dramatically: low-cycle fatigue conditions will be replaced by the elastic fatigue condition, and Palmgren–Minor rule of linear accumulation of damages could be used instead of one of the numerous Coffin–Manson models to assess the lifetime of the material.

A new creep–fatigue life model of lead-free solder joint

Life prediction plays an important role in reliability design of electronic product. Solder joint failure is one of the most common failure modes for electronic packaging structure. Current creep–fatigue life models of solder joints are unable to distinguish the creep damage and fatigue damage. In this work, a new creep–fatigue life model was proposed for solder joint tested under high strain rate, where the creep damage was based on Monkman–Grant equation and the fatigue damage was evaluated employing the Coffin–Manson model. Then, linear damage rule was utilized to build the new model. Creep test, fatigue test and creep–fatigue test were conducted respectively in order to determine the parameter in the new model. At last, the experimental result was compared with the predicted result, which shows that the calculation life meets well with the experimental life under high strain rate.

Characterization of Low Cycle Fatigue Performance of New Ferritic P92 Steel at High Temperature: Effect of Strain Amplitude

Low cycle fatigue (LCF) tests were performed at various strain amplitudes ranging from 0.2 to 0.8% to investigate the effects of strain amplitude on cyclic softening behavior and LCF lifetime of new ferrtic P92 steel. LCF tests were conducted under strain controlled in fully reversed manner with strain rate of 1.0 × 10−3 s−1 at high temperature of 650 °C. A novel fatigue life end criterion was adopted in this analysis. The effects of strain amplitude on the cyclic softening behavior, the evolution of plastic strain amplitude, hysteresis loop area, and the fatigue life were discussed. Similar softening curves were achieved except for the strain amplitude of 0.2%. The evolution of hysteresis loop areas at the smaller strain range amplitude (less than 0.4%) is contrary to the larger ones. A modified life prediction model was proposed based on Coffin–Manson model and energy‐based model, comparison of predicted lifetime and experimental data shows that the model gives a good estimation. In order to better understand the basic stress‐strain behavior, time‐independent cyclic plasticity model was used to represent the cyclic mechanical behavior of this steel. Comparison of the simulated and experimental results shows that the proposed model can give a reasonable prediction of stress‐strain hysteresis loop for P92 steel at high temperature.

Low-cycle fatigue failure behavior and life evaluation of lead-free solder joint under high temperature

In this study, low-cycle fatigue test was conducted for a lead-free solder joint at two test temperatures (348K, 398K) and three strain amplitudes (3%, 4%, and 8%). Fatigue failure behavior was analyzed and the fatigue life was evaluated using the Coffin–Manson relationship and Morrow energy-based model. The results show that the maximum load gradually drops with increasing the number of loading cycles. When the strain range or temperature is low, the maximum load drop curve can be divided into three stages. Then, it degrades into a linear stage with increasing the strain range or temperature. Both the softening of solder and the reduction of effective load-bearing area are responsible for the maximum load drop depending on the test condition. Fatigue crack initiates at the corner of the solder joint and propagates along the strain concentrated zone. Spacing distance between fatigue striations is enlarged with increasing the temperature in accordance with the degradation of fatigue resistance. In addition, both the Coffin–Manson model and Morrow energy-based model can be used to evaluate the fatigue life of solder joint under high temperature. The fatigue ductility exponent α in Coffin–Manson model and the fatigue ductility coefficient C in Morrow model are dependent on temperature, whereas other parameters in these two models keep stable under different temperature.

Fatigue behaviour and life prediction of lateral notched round bars under bending–torsion loading

Fatigue behaviour of lateral notched round bars made of DIN 34CrNiMo6 high strength steel under single bending, single torsion and combined bending–torsion was studied. Crack initiation and crack growth were monitored in situ using a high-resolution digital system. Fracture surfaces were examined by scanning electron microscopy and were replicated with a three-dimensional laser scanner. The notch effect was analysed using the equivalent strain energy density concept and the fatigue life predictions were carried out through the Coffin–Manson model. Criteria based on the principal stress field were proposed to predict the most likely initiation sites, surface crack paths and surface crack angles. Finally, very good correlations between experimental and predicted fatigue lives were observed, particularly for lives greater than 104cycles.

Quantitative Relationship between Strain and Acoustic Emission Response in Monitoring Fatigue Damage

This study was carried out to investigate the relationship between the strain and acoustic emission (AE) signals, thus, to confirm the capability of AE technique to monitor the fatigue failure mechanism of a steel component. To achieve this goal, strain and AE signals were captured on the steel specimen during the cyclic fatigue test. Both signals were collected using specific data acquisition system by attaching the strain gauge and AE piezoelectric transducer simultaneously at the specimen during the test. The stress loading used for the test was set at 600 MPa, and the specimens were fabricated using the SAE 1045 carbon steel. The related parameters for both signals were determined at every 2000 seconds until the specimen failed. It was found that a meaningful correlation of all parameters, i.e. amplitude, kurtosis and energy, was established. Finally, all AE parameters are correlated with the damage values, which have been estimated using the Coffin-Manson model. Hence, it was suggested that the AE technique can be used as a monitoring tool for fatigue failure mechanism in a steel component.

Interconnect Reliability Characterization of a High-Density 3-D Chip-on-Chip Interconnect Technology

This paper investigates the solder interconnect reliability of a high-density 3-D chip-on-chip technology under an accelerated thermal cycling (ATC) test condition through finite element (FE) modeling and experimental validation. The fabrication of the 3-D chip-on-chip technology is accomplished with a two-step gap control bonding process to minimize the solder squeezing phenomenon. The alternative goal of this paper is placed on the influences of underfill on the interconnect failure mechanism and reliability. With the calculated plastic strain, the thermal fatigue life of the most critical solder interconnect can be estimated through an empirical Coffin-Manson fatigue life prediction model. The effectiveness of the proposed FE modeling is demonstrated through ATC tests. Finally, to identify the parameters most affecting the lead-free solder interconnect reliability, both parametric FE analysis and a simulation-based experimental design scheme based on a response surface methodology are carried out with the validated FE model. Both the numerical and experimental results that underfill can not only change the interconnect failure mechanism from an interfacial crack between the Al pad and the copper (Cu) layer of the under bump metallurgy to a cohesive solder failure, but also greatly improve the solder interconnect thermal fatigue life by as much as 2.5 times. Furthermore, the experimental design demonstrates that both the Young's modulus of intermetallic compound and thermal expansion coefficient of underfill are identified as the parameters most affecting the solder interconnect reliability of the 3-D chip-on-chip technology.

Reliability Design of Multirow Quad Flat Nonlead Packages Based on Numerical Design of Experiment Method

A design of experiment (DOE) methodology based on numerical simulation is presented to improve thermal fatigue reliability of multirow quad flat nonlead (QFN) packages. In this method, the influences of material properties, structural geometries, and temperature cycling profiles on thermal fatigue reliability are evaluated, a L27(38) orthogonal array is built based on Taguchi method to figure out optimized factor combination design for promoting thermal fatigue reliability. Analysis of variance (ANOVA) is carried out to examine the influence of factors on the thermal fatigue reliability and to find the significant factors. Anand constitutive model is adopted to describe the viscoplastic behavior of lead-free solder Sn3.0Ag0.5Cu. The stress and strain in solder joints under temperature cycling are studied by 3D finite element (FE) model. The modified Coffin–Manson model is employed to predict the fatigue life of solder joints. Results indicate that the coefficients of thermal expansion (CTE) of printed circuit board (PCB), the height of solder joint, and CTE of epoxy molding compound (EMC) have critical influence on thermal fatigue life of solder joints. The fatigue life of multirow QFN package with original design is 767 cycles, which can be substantially improved by 5.43 times to 4165 cycles after the optimized factor combination design based on the presented method.

Characterization of Solder Joint Reliability Using Cyclic Mechanical Fatigue Testing

This article summarizes the mechanics of two mechanical fatigue methods, cyclic bending fatigue and shear fatigue, in inducing failure in solder joints in package assemblies, and it presents the characteristics of fatigue failures resulting from these methods using example cases of Sn-Pb eutectic and Sn-rich Pb-free solder alloys. Numerical simulation suggests that both testing configurations induce fatigue failure by the crack-opening mode. In the case of bending fatigue, the strain induced by the bending displacement is found to be sensitive to chip geometry, and it induces fatigue cracks mainly at the solder matrix adjacent to the printed circuit board interface. In case of shear fatigue, the failure location is firmly fixed at the solder neck, created by solder mask, where an abrupt change in the solder geometry occurs. Both methods conclude that the Coffin–Manson model is the most appropriate model for the isothermal mechanical fatigue of solder alloys. An analysis of fatigue characteristics using the frame of the Coffin–Manson model produces several insightful results, such as the reason why Pb-free alloys show higher fatigue resistance than Sn-Pb alloys even if they are generally more brittle. Our analysis suggests that it is related to higher work hardening. All these results indicate that mechanical fatigue can be an extremely useful method for fast screening of defective package structures and also in gaining a better understanding of fatigue failure mechanism and prediction of reliability in solder joints.

Acoustic Emission Evaluation of Fatigue Life Prediction for a Carbon Steel Specimen using a Statistical-Based Approach

Abstract This study was carried out to investigate the relationship between the strain and acoustic emission (AE) signals to ascertain the applicability of AE in predicting the fatigue life of metallic specimens. This paper is an extension research of previous work that has been published before. Previous paper presents the ability of AE to predict the fatigue life using statistical parameters such as root mean square (r.m.s) and kurtosis. The same approach also has been carried out in this recent paper but this time, the common parameters that can be directly extracted from the AE data acquisition system were used. To achieve the objective, the strain and AE signals were measured using a strain gauge and a AE piezoelectric transducer on SAE 1045 steel specimens. These measurements were conducted during the cyclic test at constant loadings of 570 MPa, 610 MPa, and 650 MPa. For data collection, AE parameters, i. e., count rate, hits, and duration, were extracted from specific software and were then correlated to fatigue lives calculated using the strain data. Fatigue life values were calculated using strain-life models. The correlation between the experimental and predicted values of fatigue life was then established by the so-called coefficient of correlation which is within 97.2 % and 98.5 % for the Coffin-Manson model and between 92.7 % and 94.3 % for the Smith-Watson-Topper model, respectively. As for the Morrow model, the coefficient of correlation was tabulated at approximately between 71.9 % and 73.6 %. Good correlation values expressed that the AE technique is applicable for predicting the fatigue life of metallic specimens.

Low-Cycle Fatigue Behavior of 95.8Sn-3.5Ag-0.7Cu Solder Joints

Low-cycle fatigue (LCF) behavior of 95.8Sn-3.5Ag-0.7Cu solder joints was investigated over a range of test temperatures (25°C, 75°C, and 125°C), frequencies (0.001 Hz, 0.01 Hz, and 0.1 Hz), and strain ranges (0.78%, 1.6%, and 3.1%). Effects of temperature and frequency on the LCF life were studied. Results show that the LCF lifetime decreases with an increase in test temperature or a decrease of test frequency, which is attributed to the longer exposure time to creep and the stress relaxation mechanism during fatigue testing. A modified Coffin–Manson model considering effects of temperature and frequency on the LCF life is proposed. The fatigue exponent and ductility coefficient were found to be influenced by both the temperature and frequency. By fitting the experimental data, the mathematical relations between the fatigue exponent and temperature, and ductility coefficient and temperature, were analyzed. Scanning electron microscopy (SEM) of the cross-sections and fracture surfaces of failed specimens at different temperature and frequency was applied to verify the failure mechanisms.

Improvement of oxidation resistance of copper by atomic layer deposition

Al2O3 films were deposited by the atomic layer deposition (ALD) technique onto pure copper at temperatures in the range 100–200°C. The chemical composition, microstructure, and mechanic properties of the ALD-deposited Al2O3 films were systematically analyzed. The variations in the film characteristics with substrate temperature were observed. Oxidation trials revealed that 20-nm-thick Al2O3 films deposited at a substrate temperature as low as 100°C suppress oxidative attack on pure copper. The Al2O3 films also showed excellent durability of adhesion strength, according to predictions using the Coffin–Manson model based on the results of accelerated temperature cycling tests. These features indicate that ALD-deposited Al2O3 film is a very promising candidate to be a protective coating for pure copper.

How to minimise thermal fatigue in surface multi-treatments and coatings?

A tool is developed to rank surface treated materials with respect to thermal fatigue. It comprises a modelling of the temperature profile in the component and an adaptation of the Coffin–Manson model for surface treatments fatigue. It is used as a performance index and discussed onto several surface treatments and multi-treatments relevant for the protection of steel in aluminium foundry moulds, exposed to thermal fatigue, with some insight in the effect of surface treatments processes on the final result. The model reproduces the well-known capability of duplex PVD nitride onto nitriding to withstand thermal fatigue. Using thermal barrier coatings may also be relevant, but the internal stress must be sufficiently compressive to be resistant to the studied thermal cycles.

Methods and calculation of mean time to failure based on Coriolis vibratory gyroscope test results

This paper uses the method of calculating the reliability of Coriolis vibrating gyroscope, based on an analysis of effects of external stress factors on the device and calculation the accelerated degradation coefficients. Methodic to calculate mean time between failures with the use of accelerated degradation coefficients is presented. To calculate the coefficients of accelerated degradation the following models were used: Arrenius model for high temperature, Coffin-Manson model for thermocycle and Holberg-Peck model for humidity. First, the failure rate and mean time between failures in operation of the gyro under normal conditions are computed and then, on the basis of these estimates, reliability parameters for the instrument in other environmental conditions are calculated with the use of environmental factors pE for specific operating conditions. As a result, the mean time between failures of Coriolis vibratory gyroscope with a metal resonator under normal operating conditions is 2,509,145 hours.

Modeling, Analysis and Fatigue Life Prediction of Lower Suspension Arm

This paper was presented the finite element modeling, analysis and fatigue life prediction of lower suspension arm using the strain-life approach. Aluminum alloys are selected as a suspension arm materials. The structural model of the suspension arm was utilizing the Solid works. The finite element model and analysis were performed utilizing the finite element analysis code. TET10 mesh and maximum principal stress were considered in the linear static stress analysis and the critical location was considered at node (6017). From the fatigue analysis, Smith-Watson- Topper mean stress correction was conservative method when subjected to SAETRN loading, while Coffin-Manson model is applicable when subjected to SAESUS and SAEBRKT loading. From the material optimization, 7075-T6 aluminum alloy is suitable material of the suspension arm.

Fatigue Failure Behaviour Study of Automotive Lower Suspension Arm

Fatigue life of automotive lower suspension arm has been studied under variable amplitude loadings. In simulation, the geometry of a sedan car lower suspension arm has been used. To obtain the material monotonic properties, tensile test has been carried out and to specify the material mechanical properties of the used material, a fatigue test under constant amplitude loading has been carried out using the ASTM standard specimens. Then, the results used in the finite element software to predict fatigue life has been evaluated later to show the accuracy and efficiency of the numerical models which they are appreciated. The finite element analysis tool is therefore proved to be a good alternative prior to the further experimental process. The predicted fatigue life from the simulation showed that Smith-Watson-Topper model provides longer life than Morrow and Coffin-Manson models. This is due to the different consideration for each strain-life model during life calculations.

A semi-empirical unified model of strain fatigue life for insulation plastics

The paper focuses on modeling the strain fatigue lives of three commonly used cable insulation polymers, namely (1) polyvinyl chloride, (2) crosslinked polyethylene, and (3) polyphenylene ether under selected strain and temperature ranges. On the basis of results obtained from their fatigue tests, Coffin–Manson model, mean/maximum strain fatigue model, and a set of new semi-empirical equations were applied to establish the relationship between fatigue lives and strains. The unified strain model, herein we name it the Wei–Wong model, is developed to predict the fatigue lives of three polymers studied and their prediction capability was examined using our experimental data. It was found that the proposed Wei–Wong model can provide a better life prediction compared to the experimental data and other methods in the literature at selected temperatures, namely −40, 25, and 65 °C.

Critical Review of the Engelmaier Model for Solder Joint Creep Fatigue Reliability

A solder interconnect fatigue life model was developed by Werner Engelmaier in the early 1980s as an improvement upon the inelastic strain range-based Coffin-Manson model. As developed, the model provides a first-order estimate of cycles to failure for SnPb solder interconnects under power and thermal cycles. While the model has been widely adopted for SnPb solder joint reliability prediction, many issues that arise from simplifications in formulating input model parameters as well as from the complex physics of solder degradation challenge the model's ability to accurately estimate cycles to failure. Deficiencies with the model have been reported by a number of researchers. This paper reviews and summarizes the major issues with the Engelmaier model in its applicability to predict solder joint thermal fatigue life.

High Cycle Cyclic Torsion Fatigue of PBGA Pb-Free Solder Joints

In this study, a comprehensive experimental and numerical approach was used to investigate high cycle cyclic torsion fatigue behavior of lead-free solder joints in a plastic ball grid array (PBGA) package. The test vehicle was a commercial laptop motherboard. The motherboard was subjected to torsional loading and life tests were conducted. Using finite element analysis (FEA), the test assembly was simulated as a global model and the BGA component was simulated as a local model. Strains measured on the motherboard surface near by the BGA were used to calibrate the FEA models. By combining the life test results and FEA simulations, a high cycle fatigue model for the lead-free solder joints was generated based on the Coffin-Manson strain-range fatigue damage model. This model can now be used to predict the cycles to failure of BGA interconnects for new electronic product design under cyclic torsion loading.

Bending Fatigue Characteristic of Sn-3.5Ag Solder Bump on Ni-UBM

Bending fatigue behavior of eutectic Sn-3.5Ag solder bump bonded on FR4-PCB was characterized by experimental and finite element method (FEM). To investigate an effect of stress state on bump failure, which had not been weighed in conventional Coffin-Manson model of Nf=K ⋅εp -1~-2, ‘fatigue frequency variable’ and ‘bump viscoplasticity’ were included in analysis procedure. As experimental results, with increasing fatigue cycles from 3,000 to 10,000, bond strength decreased from 98.9% to 76.5%, and from 97.5% to 67.1% at the fatigue frequencies of 2.5Hz and 5.0Hz, respectively. Stress state could be critical components to determine fatigue life, which should be combined in Coffin-Manson criteria. FEM calculation showed that higher bending frequency led to higher normal stress development at the solder and IMC interface, but smaller plastic strain in bump. However, bending fatigue experiment revealed discrepant results from that of Coffin-Manson criteria. Higher bending frequency, which was predicted to give rise to smaller εp at solder, showed dramatic bond deterioration of solder bump on UBM (under bump metallurgy). This was confirmed experimentally through SEM (scanning electron microscopy) observation as cracks were found at the solder bump and UBM interfacial IMC, Ni3Sn4, in case of the higher bending frequency.