Understanding the effect of dwell time on fatigue life of packages using thermal shock and intrinsic material behavior

Sahasrabudhe, S.; Monroe, Eric M.; Tandon, Shalabh; Patel, M.

doi:10.1109/ectc.2003.1216398

Cited by 10 publications

(4 citation statements)

References 10 publications

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“…12, the power law exponent is determined to be 1.80 for eutectic Pb/Sn solder. This power law exponent in mechanical fatigue is almost identical to the exponent determined in temperature cycles [11]. This agrees with the observation of Darveaux and Syed when they compare the exponent in thermal fatigue and mechanical fatigue [2].…”

Section: B Acceleration Factor For Reliabilitysupporting

confidence: 87%

Handheld Use Condition-Based Bend Test Development

Mercado

Phillips

Sahasrabudhe

et al. 2006

IEEE Trans. Adv. Packag.

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For handheld electronic applications such as cell phones and personal digital assistants (PDAs), repeated key strokes could result in considerable flexure of the printed circuit board (PCB) mounted inside the housing. In this study, a standardized four-point bend test, including test board design, test setup, and test input level, has been developed. The S-N curve has been obtained by plotting the reliability at all deflection levels as a function of solder joint strain energy density. The effect of test frequency has also been evaluated. The reliability model prediction of three-point bend reliability matches the experimental data extremely well. The transfer function between reliability stressing and field condition is a strain-energy-density-based power law relationship. Finite-element simulation has been conducted for the worst case cell phone subjected to key presses. The use condition data including strain profiles and frequency have been incorporated in the field life prediction. The four-point bend performance can be converted into the component reliability during cell phone field use conditions. This study establishes the correlation between the use conditions and reliability tests. The cyclic four-point bend test will be implemented in the Joint Electron Device Engineering Council (JEDEC) bend test standard for handheld components.Index Terms-Cell phone, cyclic bending, field conditions, finiteelement modeling, four-point bend, handheld, key presses, life prediction, personal digital assistant (PDA), reliability testing, solder joint fatigue, three-point bend.

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Section: B Acceleration Factor For Reliabilitysupporting

confidence: 87%

Handheld Use Condition-Based Bend Test Development

Mercado

Phillips

Sahasrabudhe

et al. 2006

IEEE Trans. Adv. Packag.

Self Cite

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“…On the other hand a longer dwell time results in an almost complete creep/stress relaxation during the hot dwell in each cycle and consequently a relatively shorter fatigue life. Further, in references [11,12] it was observed that the increase in the hold/dwell time dramatically reduces the number of cycles to failure for solder and leads to a saturation in cycles to failure. Therefore, it is crucial to allow just "sufficient" relaxation in the solders during test conditions so that one can accurately relate the life under test conditions to the life in the majority of the field use conditions.…”

Section: Thermal Profilementioning

confidence: 98%

“…Therefore, it is crucial to allow just "sufficient" relaxation in the solders during test conditions so that one can accurately relate the life under test conditions to the life in the majority of the field use conditions. To understand the effect of dwell times on the fatigue life of SAC solders, Sahasrabuddhe et al [12] conducted thermal shock tests. They found that the fatigue life was most sensitive to hot dwell times in the range of 5 to 10 minutes.…”

Section: Thermal Profilementioning

confidence: 99%

Powercycling Reliability, Failure Analysis and Acceleration Factors of Pb-Free Solder Joints

Setty

Subbarayan

Nguyen³

Proceedings Electronic Components and Technology, 2005. ECTC '05.

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At the present time, life acceleration factors for solder joints made of SnAgCu (SAC) ternary alloys between accelerated tests and field use conditions are not well understood. Further, the cycle time for accelerated testing of Pb-free solders is currently an industry concern since the rate of damage accumulation due to thermomechanical loading in Pb-free solders is different from the eutectic Sn-Pb solders. In this study, we develop an understanding of the acceleration factors through a combination of temperature cycling tests, powercycling tests and validated damage modeling.We begin by describing a recently developed Simulated Power Cycling (SPC) tester that is a simplified powercycling test procedure. The tester uses an external thermoelectric device to heat the package surface. Through localized heating, the thermoelectric device enables rapid cycling of packages unlike in thermal chambers. We report temperature and powercycling reliability data on Pb-free, Sn4Ag0.5Cu 36 I/O Wafer Level-Chip Scale Packages (WL-CSP). We compare the results of powercycling against -40 o to 125 o C temperature cycling test results. In both, fatigue failure by near interfacial crack growth was discovered to progress from the outside edge of the joints towards the center of the package. Creep and shear dominated microscopic failure modes were found on the solder joint fracture surfaces. Further, we observe in both cases that there are no diagonal cracks, secondary cracks are scarce and the effect of voids on crack growth is insignificant compared to the location of the joint on the package, which determines the stress on the joint. The fracture morphology due to fatigue crack growth was nearly identical close to and far from the crack initiation site, revealing similar damage mechanisms during all stages of life.Finally, we propose a procedure for extracting acceleration factors based on a recently developed (and experimentally validated for Sn-Pb solder joints) damage accumulation theory inspired by the cohesive zone models of modern fracture mechanics. The proposed model is nonempirical unlike the Coffin-Manson rule and simulates the actual progression of crack through the joint.

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“…Sahasrabudhe et al [1] conducted a series of tests to identify the impact of dwell time on cycles to failure for the second-level solder joint interconnect. Their experimental results showed that the fatigue life of eutectic SnPb solder joints decreases significantly when the dwell time is increased from 15 minutes to 30 minutes and then 90 minutes.…”

Section: Introductionmentioning

confidence: 99%

Field Condition Reliability Assessment for SnPb and SnAgCu Solder Joints in Power Cycling Including Mini Cycles

Pei

Fan²,

Bhatti

56th Electronic Components and Technology Conference 2006

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Actual field conditions that computer components such as microprocessors experience are different from the accelerated thermal cycling tests typically used to perform reliability assessment. Field conditions can include longer dwell times, different temperature ramp rates driven by power ON/OFF events, and temperature fluctuations during the power ON state due to workload patterns. Series of numerical simulations have been performed to study the effect of the field conditions on the solder joint fatigue life of electronic packaging. The simulation results show that SnPb and SnAgCu solders respond differently with respect to dwell time and mini cycles. Without considering the effect of minicycles, it is possible that SnAgCu may fail earlier than SnPb with very long dwell time. However, it is important to note if mini-cycles contribute to damage as seen in this analysis, the SnPb solder will probably still fail before SnAgCu solder.

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Understanding the effect of dwell time on fatigue life of packages using thermal shock and intrinsic material behavior

Cited by 10 publications

References 10 publications

Handheld Use Condition-Based Bend Test Development

Handheld Use Condition-Based Bend Test Development

Powercycling Reliability, Failure Analysis and Acceleration Factors of Pb-Free Solder Joints

Field Condition Reliability Assessment for SnPb and SnAgCu Solder Joints in Power Cycling Including Mini Cycles

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