Comparison of LCC Solder Joint Life Predictions With Experimental Data

1995 ◽  
Vol 117 (2) ◽  
pp. 109-115 ◽  
Author(s):  
Liang-chi Wen ◽  
Ronald G. Ross
Keyword(s):  
Solder Joint ◽  
Cyclic Strain ◽  
Peak Stress ◽  
Temperature Cycling ◽  
Temperature Cycle ◽  
Strain History ◽  
Test Program ◽  
Test Vehicle ◽  
Creep Fatigue ◽  
Life Predictions

The ability of solder joint life-prediction algorithms to predict the failure of solder joints due to temperature-cycling induced creep-fatigue has been investigated using representative leadless chip carriers (LCCs) as the test vehicle. Four different algorithms are assessed: the classic Coffin-Manson algorithm, a modified Coffin-Manson algorithm with dependency on peak stress, and two strain-energy based algorithms. JPL’s special purpose nonlinear finite element computer program was used to dynamically simulate the solder joint response to the standard NASA temperature cycling environment, which ranges from −55°C to +100°C with a 4-hour period. The computed stress-strain history provided the inputs needed by each of the failure algorithms. To test the accuracy of the analytical predictions, three different sizes of LCCs (68 pins, 28 pins, and 20 pins) were subjected to an experimental test program using the same 4-hour temperature cycle as used in the analytical predictions. The three different sized ceramic packages, each with a 50-mil pitch, provided a range of cyclic strain ranges and solder fillet geometries so as to test the algorithms against realistic electronic packaging variables. The study highlights limitations in the historical Coffin-Manson relationship, and points up possible improvements associated with incorporating a stress modifier into the Coffin-Manson equation. This modification is also somewhat simpler and more accurate than the energy-density based algorithms, which also performed quite well.

A Numerical Study of Fatigue Life of J-Leaded Solder Joints Using the Energy Partitioning Approach

1993 ◽  
Vol 115 (4) ◽  
pp. 416-423 ◽  
Author(s):  
S. Verma ◽  
A. Dasgupta ◽  
D. Barker
Keyword(s):  
Fatigue Life ◽  
Solder Joint ◽  
Numerical Study ◽  
Elastic Strain Energy ◽  
Energy Partitioning ◽  
Temperature Cycling ◽  
Temperature Cycle ◽  
Strain History ◽  
Stress And Strain ◽  
Solder Joint Fatigue

A surface-mount J-leaded device is modeled in this study, to investigate the effects of selected design, loading and manufacturing variables on solder joint fatigue life. The solder is modeled as a viscoplastic material, while the remaining materials are assumed to be linear elastic, as a first order approximation. Finite element analysis is used to determine the stress and strain history in the solder, due to temperature cycling. A “typical” temperature cycle with uniform dwell periods is applied to the solder joint. The computed stress and strain histories are utilized to construct hysteresis plots at each location in the solder joint. The hysteresis plots are then partitioned into elastic strain energy, plastic work and creep work dissipation. The fatigue life of the solder joint is then estimated through the energy partitioning technique. Parametric studies are conducted to investigate qualitatively the dependence of solder joint fatigue life on selected material properties, geometric variables, life cycle as well as accelerated loads, and manufacturing variabilities.

A rig for controlled cyclic strain and temperature testing

1982 ◽  
Vol 17 (1) ◽  
pp. 45-52 ◽  
Author(s):  
D J Beauchamp ◽  
E G Ellison
Keyword(s):  
Mechanical Strain ◽  
Thermal Strain ◽  
Cyclic Strain ◽  
Heating System ◽  
Temperature Cycle ◽  
Transient Temperature ◽  
Microprocessor System ◽  
Hydraulic Test ◽  
Heating And Cooling ◽  
Phase Temperature

A servo-hydraulic test rig capable of applying combined temperature and strain or load cycles has been developed and commissioned. The nature of the test has dictated the specimen form as a hollow, hour-glass type. The critical problem of a suitable extensometer for temperature and strain cycling has been solved. The device designed and produced shows negligible transient temperature effects, has a high resolution of better than 0.1 μm, and is mechanically very stable. The heating and cooling is controlled by an induction heating system with grip cooling; additional cooling is available using compressed air passing through the hollow specimen. The system is capable of following a temperature ramp to within 1°C linearity. The thermal strain associated with a temperature cycle is compensated for using a microprocessor system specially developed for the purpose, which also enables a mechanical strain-stress loop to be plotted during a test. Both ‘in-phase’ and ‘out-of-phase’ temperature/strain cycles have been carried out and development continues to include dwell periods.

scholarly journals Extreme PCR: Efficient and Specific DNA Amplification in 15–60 Seconds

2015 ◽  
Vol 61 (1) ◽  
pp. 145-153 ◽  
Author(s):  
Jared S Farrar ◽  
Carl T Wittwer
Keyword(s):  
High Resolution ◽  
Single Molecule ◽  
High Resolution Melting ◽  
Dna Amplification ◽  
Temperature Cycling ◽  
High Yield ◽  
Temperature Cycle ◽  
Amplification Efficiency ◽  
Analytical Sensitivity ◽  
Agarose Gels

Abstract BACKGROUND PCR is a key technology in molecular biology and diagnostics that typically amplifies and quantifies specific DNA fragments in about an hour. However, the kinetic limits of PCR are unknown. METHODS We developed prototype instruments to temperature cycle 1- to 5-μL samples in 0.4–2.0 s at annealing/extension temperatures of 62 °C–76 °C and denaturation temperatures of 85 °C–92 °C. Primer and polymerase concentrations were increased 10- to 20-fold above typical concentrations to match the kinetics of primer annealing and polymerase extension to the faster temperature cycling. We assessed analytical specificity and yield on agarose gels and by high-resolution melting analysis. Amplification efficiency and analytical sensitivity were demonstrated by real-time optical monitoring. RESULTS Using single-copy genes from human genomic DNA, we amplified 45- to 102-bp targets in 15–60 s. Agarose gels showed bright single bands at the expected size, and high-resolution melting curves revealed single products without using any “hot start” technique. Amplification efficiencies were 91.7%–95.8% by use of 0.8- to 1.9-s cycles with single-molecule sensitivity. A 60-bp genomic target was amplified in 14.7 s by use of 35 cycles. CONCLUSIONS The time required for PCR is inversely related to the concentration of critical reactants. By increasing primer and polymerase concentrations 10- to 20-fold with temperature cycles of 0.4–2.0 s, efficient (>90%), specific, high-yield PCR from human DNA is possible in <15 s. Extreme PCR demonstrates the feasibility of while-you-wait testing for infectious disease, forensics, and any application where immediate results may be critical.

Wire Fatigue Models for Power Electronic Modules

2003 ◽  
Author(s):  
Karumbu Nathan Meyyappan ◽  
Peter Hansen ◽  
Patrick McCluskey
Keyword(s):  
Prediction Model ◽  
Life Prediction ◽  
Damage Model ◽  
Cyclic Strain ◽  
Temperature Cycling ◽  
Transformation Model ◽  
Time To Failure ◽  
Flexural Failure ◽  
The Wire ◽  
Life Prediction Model

This paper presents two, semi-analytical, physics-of-failure based life prediction model formulations for flexural failure of wires ultrasonically wedge bonded to pads at different heights. The life prediction model consists of a load transformation model and a damage model. The load transformation model determines the cyclic strain is created by a change in wire curvature at the heel of the wire resulting from expansion of the wire and displacement of the frame. The damage model calculates the life based on the strain cycle magnitude and the elastic-plastic fatigue response of the wire. The first formulation provides quick calculation of the time to failure for a wire of known geometry. The second formulation optimizes the wire geometry for maximum time to failure. These model formulations support virtual qualification of power modules where wire flexural fatigue is a dominant failure mechanism. The model has been validated using temperature cycling test results.

Influence of cyclic load input on the mechanical properties of a sensitive soil from Orleans, Ontario

1980 ◽  
Vol 17 (4) ◽  
pp. 498-508 ◽  
Author(s):  
R. N. Yong ◽  
D. Taplin ◽  
G. Wiseman
Keyword(s):  
Mechanical Properties ◽  
Laboratory Test ◽  
Dynamic Loading ◽  
Cyclic Strain ◽  
Peak Stress ◽  
Confining Pressure ◽  
Constant Load ◽  
Deviatoric Stress ◽  
General Terms ◽  
Stress Levels

The importance of disturbance and remoulding to the alteration of mechanical properties of sensitive soils has been well documented in the geotechnical literature both in terms of laboratory and field behaviours. Man-made transient dynamic input such as dynamite blasting, heavy vehicles, and train movement have been suspected of being capable of causing a reduction in the in situ strength parameters of sensitive clays. A laboratory test program was undertaken to determine whether dynamic loading at peak stress levels below normal failure strength caused similar changes in the mechanical properties, and specifically to quantify the phenomena.In order to simulate highly overconsolidated conditions most of the tests were carried out under conditions of no confining pressure, although supplemental data were obtained from consolidated undrained tests. Some of the variables examined in this program were confining pressure, mean deviatoric stress, cyclic deviatoric stress, cyclic strain, number of applications, frequency, and reference strength. In order to compare the effect of dynamic input with the long-term creep phenomena, a simultaneous constant load program was undertaken.In general terms, the study indicates that under the prestated laboratory test conditions no major reduction in peak strength was found under dynamic loading, and that failure would occur at comparative stress levels under dead-load conditions, but required a greater time. In addition, examination of the sample after failure revealed that any remoulding of the sample appeared to be restricted to the area adjacent to the shear zone.

Solder Joint Reliability of SnBi Finished TSOPs with Alloy 42 Lead-Frame under Temperature Cycling

2011 ◽  
pp. 74-74-15 ◽  
Author(s):  
Weiqiang Wang ◽  
Michael Osterman ◽  
Diganta Das ◽  
Michael Pecht
Keyword(s):  
Solder Joint ◽  
Temperature Cycling ◽  
Lead Frame ◽  
Solder Joint Reliability ◽  
Joint Reliability

Influence Of Solder Joint Shape On The Thermo-Mechanical Reliability Of CSP's

2004 ◽  
Vol 1 (2) ◽  
pp. 53-63 ◽  
Author(s):  
Co van Veen ◽  
Bart Vandevelde ◽  
Eric Beyne
Keyword(s):  
Solder Joint ◽  
Force Constant ◽  
Local Stress ◽  
Simulation Software ◽  
Temperature Cycling ◽  
Circuit Board ◽  
Surface Evolver ◽  
Joint Shape ◽  
Profile Estimation ◽  
Analytical Expressions

Not only the stand-off height but also the shape of a solder joint has a strong influence on the joint reliability under temperature cycling. The shape determines the size of the local stress and strain concentrations. It is therefore very important to know well the joint shape after reflow. In a previous paper closed analytical expressions were derived for liquid bump shapes, as a function of pad size and bump height [1]. The bump deformation as a function of the chip weight could be derived from the force constant. In the present paper closed analytical expressions are derived for the force constant for liquid bumps having unequal spherical pad sizes. It turns out that the force constant for compression can be optimized as a function of the ratio of those pad sizes. The shape of the bump and especially the contact angle is of interest for modeling activities where geometrical effects do play a role. Furthermore from the variation in bumps heights on a chip an estimate can be made of the tilt of the chip after assembly. The solder profile estimation by the analytical expressions is validated by experimental results. Also a comparison with the solder profile estimation by the simulation software Surface Evolver is done. Both comparisons showed that the analytical estimation of the standoff height is very good as long as the gravitation energy contributed by the chip weight is less than 10% of the total energy. Finally, an example is shown where the analytical model and Surface Evolver are the geometrical input for a finite element model. The example considers a CSP assembled at both sides of the printed circuit board.

Design and Direct Assembly of 2.5D/3D Rigid Silicon Interposer on PCB

2014 ◽  
Vol 2014 (1) ◽  
pp. 000783-000786 ◽  
Author(s):  
Farhang Yazdani
Keyword(s):  
Flip Chip ◽  
Thermal Stresses ◽  
Stress Test ◽  
Temperature Cycle ◽  
3D Integration ◽  
Test Vehicle ◽  
Direct Assembly ◽  
Solder Balls ◽  
Present Design ◽  
The Cost

Silicon interposer is emerging as a vehicle for integrating dies with sub 50um bump pitch in 2.5D/3D configuration. Benefits of 2.5D/3D integration are well explained in the literature, however, cost and reliability is a major concern especially with the increase in interposer size. Among the challenges, reliability issues such as warpage, cracks and thermal-stresses must be managed, in addition, multi-layer build-up flip chip substrate cost and its impact on the overall yield must be considered. Because of these challenges, 2.5D/3D silicon interposer has developed a reputation as a costly process. To overcome the reliability challenges and cost associated with typical thin interposer manufacturing and assembly, a rigid silicon interposer type structure is disclosed. In this study, interposer with thickness of greater than 300um is referred to as rigid interposer. Rigid silicon interposer is directly assembled on PCB without the need for intermediary substrate. This eliminates the need for an intermediary substrate, thin wafer handling, wafer bonding/debonding procedures and Through Silicon Via (TSV) reveal processes, thus, substantially reducing the cost of 2.5D/3D integrated products while improving reliability. A 10X10mm2 rigid silicon interposer test vehicle with 310um thickness was designed and fabricated. BGA side of the interposer with 1mm ball pitch was bumped with eutectic solder balls through a reflow process. Interposer was then assembled on a 50X50mm2 FR-4 PCB. We present design and direct assembly of the rigid silicon interposer on PCB followed by temperature cycle results using CSAM images at 250, 500, 750 and 1000 cycles. It is shown that all samples successfully passed the temperature cycle stress test.

Thermal Fatigue Prediction for Leadless Solder Joint of TFBGA

2006 ◽  
Author(s):  
Chia-Lung Chang ◽  
Tzu-Jen Lin ◽  
Chih-Hao Lai
Keyword(s):  
Energy Density ◽  
Solder Joint ◽  
Creep Strain ◽  
Thermal Fatigue ◽  
Strain Energy Density ◽  
Strain Energy ◽  
Creep Property ◽  
Inelastic Strain ◽  
Temperature Cycling ◽  
Element Analysis

Nonlinear finite element analysis was performed to predict the thermal fatigue for leadless solder joint of TFBGA Package under accelerated TCT (Temperature Cycling Test). The solder joint was subjected to the inelastic strain that was generated during TCT due to the thermal expansion mismatch between the package and PCB. The solder was modeled with elastic-plastic-creep property to simulate the inelastic deformation under TCT. The creep strain rate of solder was described by double power law. The furthest solder away from the package center induced the highest strain during TCT was considered as the critical solder ball to be most likely damaged. The effects of solder meshing on the damage parameters of inelastic strain range, accumulated creep strain and creep strain energy density were compared to assure the accuracy of the simulation. The life prediction equation based on the accumulated creep strain and creep strain energy density proposed by Syed was used to predict the thermal fatigue life in this study. The agreement between the prediction life and experimental mean life is within 25 per cent. The effect of die thickness and material properties of substrate on the life of solder was also discussed.

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