Fatigue Life of Sn3.0Ag0.5Cu Solder Alloy Under Combined Cyclic Shear and Constant Tensile/Compressive Loads

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Travis Dale ◽  
Yuvraj Singh ◽  
Ian Bernander ◽  
Ganesh Subbarayan ◽  
Carol Handwerker ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Axial Load ◽  
Solder Joints ◽  
Axial Loads ◽  
Cyclic Shear ◽  
Lap Shear ◽  
Shear Loads ◽  
Area Array ◽  
Compressive Loads ◽  
The Impact

Abstract Solder joints in electronic assemblies experience damage due to cyclic thermomechanical loading that eventually leads to fatigue fracture and electrical failure. While solder joints in smaller, die-sized area-array packages largely experience shear fatigue due to thermal expansion mismatch between the component and the substrate, larger area-array packages experience a combination of cyclic shear and axial tensile/compressive loads due to flexure of the substrate. Additionally, on larger processor packages, the attachment of heatsinks further exacerbates the imposed axial loads, as does package warpage. With the increase in size of packages due to 2.5D heterogeneous integration, the above additional axial loads can be significant. Thus, there exists a critical need to understand the impact on fatigue life of solder joints with superposed compressive/tensile loads on the cyclic shear loads. In this paper, we describe a carefully constructed multi-axial microprecision mechanical tester as well as fatigue test results on Sn3.0Ag0.5Cu (SAC305) solder joints subjected to controlled cyclic shear and constant compressive/tensile loads. The tester design allows one to apply cyclic shear loads up to 200 N while maintaining a constant axial load of up to 38 N in tension or compression. The tester is capable of maintaining the axial load to within a tolerance of ±0.5 N during the entirety of fatigue experiment. Carefully constructed test specimens of Sn3.0Ag0.5Cu solder joints were isothermally fatigued under systematically increased compressive and tensile loads imposed on the test specimen subject to repeated loading (R = 0) under lap-shear. In general, the imposition of the superposed compressive load increases the fatigue life of the solder joint compared to application of pure cyclic shear, while the imposition of the superposed tensile load decreases the fatigue life. At larger compressive loads, friction between fractured surfaces is responsible for significant energy dissipation during the cyclic load–unload cycles.

Fatigue Life of Sn3.0Ag0.5Cu Solder Alloys Under Combined Shear and Compressive Loads

2019 ◽  
Author(s):  
Travis Dale ◽  
Yuvraj Singh ◽  
Ian Bernander ◽  
Ganesh Subbarayan ◽  
Carol Handwerker ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Solder Joints ◽  
Compressive Load ◽  
Axial Loads ◽  
Cyclic Shear ◽  
Lap Shear ◽  
Shear Loads ◽  
Area Array ◽  
Compressive Loads ◽  
The Impact

Abstract Solder joints in electronic assemblies experience damage due to cyclic thermomechanical loading that eventually leads to fatigue fracture and electrical failure. While solder joints in smaller, die-sized area-array packages largely experience shear fatigue due to thermal expansion mismatch between the component and the substrate, larger area-array packages experience a combination of cyclic shear and axial tensile/compressive loads due to flexure of the substrate. Additionally, on larger processor packages, the attachment of heatsinks further exacerbates the imposed axial loads, as does package warpage. With the increase in size of packages due to 2.5D Heterogeneous integration, the above additional axial loads can be significant. Thus, there exists a critical need to understand the impact on fatigue life of solder joints with superposed compressive/tensile loads on the cyclic shear loads. In this paper, we describe a carefully constructed microscale mechanical tester as well as fatigue test results on Sn3.0Ag0.5Cu (SAC305) solder joints subjected to controlled cyclic shear and constant compressive loads. The tester design allows one to apply cyclic shear loads up to 200 N while maintaining a constant axial load of up to 38 N in tension or compression. The tester is capable of maintaining the compressive load to within a tolerance of +/− 0.5 N during the entirety of fatigue experiment. Carefully constructed samples of Sn3.0Ag0.5Cu solder joints were isothermally fatigued under systematically increased compressive load imposed on the sample subject to repeated loading (R = 0) under lap-shear. In general, the imposition of the superposed compressive load increases the fatigue life of the solder joint compared to application of pure cyclic shear load. At larger compressive loads, friction between fractured surfaces is responsible for significant energy dissipation during the cyclic load-unload cycles.

A Damage Mechanics-Based Fatigue Life Prediction Model for Solder Joints

2003 ◽  
Vol 125 (1) ◽  
pp. 120-125 ◽  
Author(s):  
Hong Tang ◽  
Cemal Basaran
Keyword(s):  
Fatigue Life ◽  
Prediction Model ◽  
Life Prediction ◽  
Damage Mechanics ◽  
Solder Joints ◽  
Experimental Results ◽  
Fatigue Life Prediction ◽  
Isotropic Hardening ◽  
Cyclic Shear ◽  
Life Prediction Model

A thermomechanical fatigue life prediction model based on the theory of damage mechanics is presented. The damage evolution, corresponding to the material degradation under cyclic thermomechanical loading, is quantified thermodynamic framework. The damage, as an internal state variable, is coupled with unified viscoplastic constitutive model to characterize the response of solder alloys. The damage-coupled viscoplastic model with kinematic and isotropic hardening is implemented in ABAQUS finite element package to simulate the cyclic softening behavior of solder joints. Several computational simulations of uniaxial monotonic tensile and cyclic shear tests are conducted to validate the model with experimental results. The behavior of an actual ball grid array (BGA) package under thermal fatigue loading is also simulated and compared with experimental results.

Effect of Corner Staking on the Fatigue Life of BGA Under Thermal Cycling

2017 ◽  
Author(s):  
Deng Yun Chen ◽  
Michael Osterman
Keyword(s):  
Fatigue Life ◽  
Thermal Cycling ◽  
Material Properties ◽  
Solder Joints ◽  
Material Selection ◽  
Temperature Cycling ◽  
Sac305 Solder ◽  
Element Analysis ◽  
Bga Packages ◽  
The Impact

Solder interconnects in electronic assemblies are susceptible to failures due to environmental high strain rate impact and cyclic stresses. To mitigate the failures, adhesive bonds can be added after the solder assembly process to provide additional mechanical support. For ball grid array (BGA) packages, the adhesive is normally applied to the corners of the package and referred to as corner staking. In addition to corner staking, underfill is also a strategy used to mitigate the stresses on the solder joints. While components with underfill has been widely studied, the study of the impact of corner staking on the reliability of packages remains limited. This paper presents a study of corner-staked BGA packages with tin-3.0 silver-0.5 copper (SAC305) solder subjected to temperature cycling. Experimental temperature cycling is conducted to examine impact of the selected corner staking material on the fatigue life of BGAs. Further, finite element analysis is conducted to understand the influence of material properties of staking material on the fatigue life of BGAs. The result of the study indicates that the presence of corner staking, with selected material properties, reduces the damage on the solder joints under thermal cycling, and thus increases its fatigue life by about 80%. This paper may serve as a guidance for staking material selection to improve the fatigue life of solder joints of BGAs under thermal cycling.

scholarly journals Influence of the axial loads of rolling stock on the contact-fatigue life of rails

2018 ◽  
Vol 77 (3) ◽  
pp. 149-156 ◽  
Author(s):  
V. S. Kossov ◽  
G. M. Volokhov ◽  
O. G. Krasnov ◽  
M. N. Ovechnikov ◽  
A. L. Protopopov ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Service Life ◽  
Contact Fatigue ◽  
Calculated Data ◽  
Operating Conditions ◽  
Rolling Stock ◽  
Axial Loads ◽  
Rolling Surface ◽  
Contact Fatigue Life ◽  
The Impact

Analysis of operational data for defective and highly defective rails showed that up to 25 % is the contact-fatigue defects. In connection with the development of heavy haul traffic on the Russian railways, it is relevant to determine the influence of cars with increased axial loads of 25 and 27 tf on the contact fatigue life of rails. The solution of this problem is set forth in this article. The Brown-Miller model of multi-axial fatigue was used in the calculation. This model is integrated into the Fatigue software system, which is tied to the Marc calculation system through Pat-ran. Since under operating conditions the wheel moves (rolls) along the rail on meandering trajectory, in computer modeling weight coefficients were taken into account that characterize the percentage of wheels in the cross-sectional areas of the rail. Calculations of contact fatigue life took into account the variability of vertical loads from the impact on the track of trains formed from innovative open cars with axial loads of 23.5, 25 and 27 tf under operating conditions, loaded with real loading blocks. According to the analysis of calculated data with an increase in axial loads from 23.5 to 25 tf, it is necessary to expect a decrease in the service life of rails in contact fatigue resistance by 19 %, with a further increase in axle loads of up to 27 tf per 32 %. Considering that the share of freight cars with axial loads of 25 tf does not exceed 15...20 %, then on the routes of its use the service life of rails should be expected to decrease by 3...4 %. The method proposed by the authors for predicting the contact fatigue life of rails with increasing axial loads is advisable to improve in part of the experimental determination of the fatigue and strength characteristics of rail steel from the degree of hardening of the rolling surface, its probabilistic properties and the use of the integral distribution law for vertical forces, taking into account the structure of the freight traffic passing through the section. The work was carried out according to the RFBR project 17-20 01088.

Optimization of Copper Column Flip Chip Packages Incorporating a Variable Interconnect Compliance Configuration

2007 ◽  
Author(s):  
Andrew A. O. Tay ◽  
Siow Ling Ho
Keyword(s):  
Fatigue Life ◽  
Flip Chip ◽  
Solder Joints ◽  
Wafer Level ◽  
Elastic Plastic ◽  
Creep Analysis ◽  
Reliability Of Solder Joints ◽  
The Impact ◽  
Plastic Creep ◽  
Copper Column

This paper describes a parametric study of the reliability of solder joints in wafer level flip chip packages that employ copper column interconnects. In this study, the impact of the change in the compliance of the copper column interconnects on the fatigue life of the solder joints were investigated by varying the diameter of the copper column interconnects. 2-D elastic-plastic finite element analyses were carried out on packages with constant interconnect diameter as well as those with variable interconnect diameters within the same package. The effect of changing the pitch and the pad size were also studied. It was found that an effective strategy in increasing the fatigue life and hence the reliability of the solder joints is by distributing copper columns of lower compliance (greater diameter) near the center of the package and increasing the compliance of the copper columns (decreasing their diameter) towards the perimeter of the chip package. In addition, elastic-plastic-creep analysis was also performed on the packages. It was observed that the results from the elastic-plastic analysis and the elastic-plastic-creep analysis exhibit the same trend.

Design of Experiments in Ball Grid Array Thermal Fatigue Life Tests

2002 ◽  
Author(s):  
T. E. Wong ◽  
C. Y. Lau ◽  
L. A. Kachatorian ◽  
H. S. Fenger ◽  
I. C. Chen
Keyword(s):  
Fatigue Life ◽  
Thermal Fatigue ◽  
Solder Joints ◽  
Ball Grid Array ◽  
Temperature Cycling ◽  
Design Parameters ◽  
Physical Analysis ◽  
Printed Wiring Board ◽  
Thermal Fatigue Life ◽  
The Impact

The objective of the present study is to evaluate the impact of electronic packaging design/manufacturing process parameters on the thermal fatigue life of ball grid array (BGA) solder joints. The four selected parameters are BGA under-fill materials, conformal coating, solder pad sizes on printed wiring board, and BGA rework, with each having either two or three levels of variation. A test vehicle (TV), on which various sizes of BGA daisy-chained packages are soldered, is first designed and fabricated, and then subjected to temperature cycling (−55°C to +125°C) with continuous monitoring of solder joint integrity. The total of 15 experimental cases is used in the present study. Based on monitored results, a destructive physical analysis is conducted to further isolate the failure locations and determine the failure mechanisms of the solder joints. Test results indicate that the influence of these design parameters on fatigue life is dependent on the particular package, in some instances improving the fatigue life tenfold.

scholarly journals Determination of maximum axial loads at the stage of operation of non-rigid pavements based on the analysis of complete deformation diagrams

2019 ◽  
Vol 6 (2) ◽  
Author(s):  
Evgenia Uglova ◽  
Artem Tiraturyan ◽  
Evgeny Roman ◽  
Evgeny Belousov
Keyword(s):  
Axial Load ◽  
Dissipated Energy ◽  
Axial Loads ◽  
Road Design ◽  
Load Limit ◽  
Proportional Increase ◽  
Complete Deformation ◽  
Definition Of ◽  
The Impact ◽  
Deformation Diagrams

The article is devoted to the development and experimental justification of the possibility of determining the axial loads of flexible pavements on the basis of full deformation diagrams recorded under shock loading. Results: The drawbacks of the existing regulatory methods for determining the axial load limit from the impact of vehicles at the operation stage are considered. It is noted that the definition of axial loads only on the strength factor, has several disadvantages associated with the need for information on the design value of the modulus of elasticity of the pavement, as well as the inconsistency of the existing regulatory framework for road design with real traffic loads. It is proposed to determine the maximum axial loads on the basis of the analysis of the complete deformation diagrams recorded at different values of the dynamic load shock load. For the first time, an approach to determining axial loads is proposed, based on the construction of a curve in the coordinates “increase of dissipated energy (ΔW) – load on the coating (F)”, and the load initiating the transition from proportional increase of the dissipated energy with increasing contact load, disproportionately. An example is given of determining the maximum axial load on the pavement cover for the exploited section of the M4 “DON” highway Conclusions: The possibility of determining the limiting axial loads on the pavement coating, based on the analysis of the complete deformation diagrams recorded during impact loading on the pavement coating, was experimentally justified. The need for further improvement and a set of a database of experimental data on changes in limiting axial loads in different periods of the year is noted.

Influence of duration and frequency of load application on the stress-strain state of the track

2018 ◽  
Vol 77 (6) ◽  
pp. 364-367
Author(s):  
M. M. Zheleznov ◽  
V. O. Pevzner ◽  
V. P. Solov’ev ◽  
A. V. Anisin ◽  
I. M. Anisina ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Axial Load ◽  
Strain State ◽  
Load Application ◽  
Axial Loads ◽  
Test Program ◽  
Stress Strain ◽  
The Road ◽  
Different Characteristics ◽  
The Impact

Abstract. In 2014–2016 on the Kovdor—Pinozero section of Oktyabrskaya Railway tests were carried out on the impact of cars with axial loads of 245.3 and 264.9 kN on the track in comparison with standard cars with an axial load of 230.5 kN. Test program included trips to five experimental sections of the track with the same construction of the track superstructure, but different parameters of the road bed. Tests carried out on the impact on the track of trains weighing from 2000 to 8000 tons at different axial loads of cars and moving at different speeds made it possible to estimate the dependence of the growth of vertical forces acting on the rail on the duration and frequency of load application. Work on the registration of vertical forces was carried out by the specialists of the Department “Tracks and track facility” of the JSC “VNIIZhT”. On the basis of the results obtained, a mathematical model was developed that describes the effect of increasing the impact of railcars on the track as the load application increases, allowing calculations for various characteristics of the base. In the future, it is planned to use this model to estimate the accumulation of deformations of the track with different characteristics of the base and variants of train load. Obtained results allow stating that the accumulation of track failures depends not only on the level of the axial load and the mass of the train, but also on the duration and frequency of the load application. 

Crack Initiation and Growth in Solder Joints Under Cyclic Shear Deformation Using Piezomechanical Actuation

2005 ◽  
Vol 129 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Dong-Jin Shim ◽  
S. Mark Spearing ◽  
Qingda Yang
Keyword(s):  
Crack Initiation ◽  
Solder Joint ◽  
Shear Deformation ◽  
Mechanical Response ◽  
Solder Joints ◽  
Image Correlation ◽  
Cyclic Shear ◽  
Perfectly Plastic ◽  
Lap Shear ◽  
Shear Strains

Crack initiation and growth behavior in solder joints under cyclic shear deformation using piezomechanical actuation have been investigated. Experiments were conducted on specimens that consist of piezo–ceramic plates and eutectic Sn–Pb solder bonded in a double-lap shear configuration. Specimens were tested under various frequencies and ranges of applied electric field at room temperature, and a shear-lag model using elastic–perfectly plastic solder properties was developed to characterize the mechanical response of the solder joint. Nominal plastic shear strain ranges from 0.182% to 2.69% were considered. The applied shear strains measured using digital image correlation showed agreement with shear strains from analyses. The Coffin–Manson relationship was used to characterize crack initiation, and a power law was employed for crack growth. This work shows that the fatigue characteristics of solder joints using piezomechanical actuation exhibit reasonable agreement with those using other types of testing methods and provides the framework for a new accelerated testing methodology for solder joint reliability.

Methodical approaches to the economic assessment of costs in the operation of cars with axial load of 27 tons at the section Kachkanar—Smychka

2018 ◽  
Vol 77 (6) ◽  
pp. 347-356
Author(s):  
G. A. Granovskaya ◽  
A. I. Safonova ◽  
O. A. Suslov ◽  
N. S. Okhotnikov
Keyword(s):  
Axial Load ◽  
Economic Effect ◽  
Economic Assessment ◽  
Axial Loads ◽  
Railway Line ◽  
Experimental Section ◽  
Calculation Algorithms ◽  
Infrastructure Maintenance ◽  
The Cost ◽  
The Impact

Abstract. The most important direction of increasing the efficiency of rail transportation is to increase the load-carrying capacity of freight cars as a result of an increase in axial loads. New car 12-9548-01 with improved technical characteristics has an axial load of 27 tons. The article describes method of calculating the coefficient reflecting the change in the impact of cars with an axial load of 27 tons on the roadbed during transportation in estimated cars compared to transportation in equivalent cars. Algorithms for calculating changes in the cost of fuel and energy costs for train traction and maintenance of the track infrastructure on the site during the operation of trains formed from cars with an axial load of 27 tons are given, as well as methods for determining the initial data for the calculation.Authors provide values of the coefficient reflecting the change in the impact of vertical and horizontal forces on the railway line when passing freight cars with an axial load of 27 tons compared to analogue cars, and the coefficient of change of the main specific resistance to motion separately for loaded and empty cars.Developed calculation algorithms and methods for obtaining baseline data allow an economic assessment of changes in infrastructure maintenance costs and fuel and energy resources for the operation of trains formed from cars with an axial load of 27 tons compared to those formed from cars with a load of 23.5 tons at the experimental section Kachkanar—Smychka.The cost change assessment carried out in 2017 shows a generally definite economic effect, while there is a reduction in costs associated with the consumption of electricity for train traction as a result of the operation of the estimated cars in the experimental section and an increase in the cost of maintaining the track superstructure and the roadbed, which is quite expected for the conditions of the organization of traffic with increased axial loads.

Sign in / Sign up

Export Citation Format

Share Document