Health Monitoring for Damage Initiation and Progression During Mechanical Shock in Electronic Assemblies

Leadfree solders have been used as interconnects in electronic packaging, due to its environmental friendly chemical property. However, those materials may experience high strain rates when subjected to shock and vibration. Consequently, failure will occur to electronics in those situations. Therefore, knowing the material properties of lead free solders are extremely important, but research on mechanical behaviors of those solder alloys at high strain rates are scarce. Anand's viscoplastic constitutive model has been widely used to describe the inelastic deformation behavior of solders in electronic components under thermo-mechanical deformation. However, Anand's model constants for the transient dynamic strain rates are scarce. In this paper, the nine material parameters to fit the Anand viscoplastic model at high strain rates have been presented. In order to develop the constants for this model, uniaxial tensile tests at several strain rates and temperatures have been completed. A constrant strain rate impact hammer which enables attaining strain rates around 1 to 100 per sec has been employed to implement tensile tests and a small thermal chamber is applied to control testing temperature. High speed cameras operating at 70,000 fps have been used to capture images of specimen and then digital image correlation method is used to calculate tensile strain. Uniaxial stress-strain curves have been plotted over a wide range of strain rates (f: =10, 35, 50, 75 /sec) and temperatures (T = 25, 50, 75, 100, 125°C). Anand viscoplasticity constants have been calculated by non-linear fitting procedures. In addition, the accuracy of the extracted Anand constants has been evaluated by comparing the model prediction and experimental data.

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Section: Introductionmentioning

confidence: 99%

Material behavior of SAC305 under high strain rate at high temperature

Lall¹,

Zhang²,

Yadav³

et al. 2014

Fourteenth Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITherm)

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“…The use of leading indicators of failure for prognostic indication of impending failure of electronics has been previously demonstrated [17][18][19][20], [25]. One important reason for using an in-situ solder-joint fault sensor is that stress magnitudes are difficult to derive, and even more challenging to keep track of [21].…”

Section: State Of the Artmentioning

confidence: 99%

Advanced testing and prognostics of Ball Grid Array (BGA) components with a stand-alone monitor IC

Bhatia

Hofmeister

Goodman

et al. 2009

2009 Ieee Autotestcon

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Ball Grid Array (BGA) packages have gained wide acceptance for use with FPGAs and the devices are used extensively for digital electronic designs. While these packages provide high interconnect densities, they rely upon an array of closely-spaced solder balls that are subject to cracking, oxidation and eventual failure. These solder joints can contribute to costly intermittencies that drive "No Fault Found" types of situations higher in the service depots. To overcome these intermittency problems, this paper presents a novel, stand-alone Integrated Circuit (IC) to be applied in systems for detection and isolation of intermittency faults in FPGAs. Because the detected faults are isolated before the FPGA begins to exhibit an intermittent failure, this provides more comprehensive approaches to supporting condition-based maintenance (CBM) and Enterprise Health Management (EHM) objectives for critical military/aerospace applications.

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“…High speed data acquiring system has been built to measure transient deformation of lead free materials at high strain rate. In the past, Digital Image Correlation (DIC) has been widely used to measure full field displacement and strain, when electronic products exposed to drop and shock events (Lall [2008). In this study, the high strain rate properties of SnlAgO.5Cu (SAC 105), Sn3AgO.5Cu (SAC305) lead-free solder alloys at high temperatures have been measured.…”

Section: Introductionmentioning

confidence: 99%

High strain-rate constitutive behavior of SAC105 and SAC305 leadfree solder during operation at high temperature

Lall

Zhang

Yadav

et al. 2015

2015 16th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and

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Industry migration to leadfree solders has resulted in a proliferation of a wide variety of solder alloy compositions. The most popular amongst these are the Sn-Ag-Cu family of alloys like SAC lOS and SAC30S. Electronics subjected to shock and vibration may experience strain rates of 1-100 per sec. Electronic product may often be exposed to high temperature during storage, operation and handling in addition to high strain rate transient dynamic loads during drop-impact, shock and .vibration. Properties of leadfree solder alloys at high stram rates at low and high temperatures experienced by the solder joint during typical mechanical shock events are scarce. Previous studies have showed the effect of high strain rates and thermal aging on the mechanical properties of leadfree alloys including elastic modulus and the ultimate tensile strength. The ANAND viscoplastic constitutive model has been widely used to describe the inelastic deformation behavior of solders in electronic components. In this study, SAC lOS and SAC30S leadfree alloys have been tested at strain rates of 10, 3S, SO and 7S per sec at various operating temperatures of SO°C, 7SoC, 100°C and 12S°C. Full-field strain in the specimen have been measured using high speed imaging at frame rates up to 7S,000 fps in combination with digital image correlation. The cross-head velocity has been measured prior-to, during, and after deformation to ensure the constancy of cross-head velocity. Stress-Strain curves have been plotted over a wide range of strain rates and temperatures. Experimental data for the pristine specimen has been fit to the ANAND's viscoplastic model.

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Health Monitoring for Damage Initiation and Progression During Mechanical Shock in Electronic Assemblies

Cited by 60 publications

References 45 publications

Material behavior of SAC305 under high strain rate at high temperature

Material behavior of SAC305 under high strain rate at high temperature

Advanced testing and prognostics of Ball Grid Array (BGA) components with a stand-alone monitor IC

High strain-rate constitutive behavior of SAC105 and SAC305 leadfree solder during operation at high temperature

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