Modified metal-insulator-metal (M-I-M) hydrogen gas sensors based on zinc oxide

Dutta, Atanu; Basu, S.

doi:10.1007/bf00144644

Cited by 26 publications

(33 citation statements)

References 14 publications

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“…22 Since the amount of La doping is quite small in the current work, the volume fraction of IMCs can be considered as close to 0.07. If the IMCs are assumed to be spherical and uniformly distributed in the eutectic region, as also considered in Ref.…”

Section: Particle Sizementioning

confidence: 97%

Impact of Thermal Aging on the Microstructure Evolution and Mechanical Properties of Lanthanum-Doped Tin-Silver-Copper Lead-Free Solders

Sadiq

Pesci

Cherkaoui

2013

Journal of Elec Materi

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is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. An extensive study is made to analyze the impact of pure lanthanum on the microstructure and mechanical properties of Sn-Ag-Cu (SAC) alloys at high temperatures. Different compositions are tested; the temperature applied for the isothermal aging is 150°C, and aging times of 10 h, 25 h, 50 h, 100 h, and 200 h are studied. Optical microscopy with cross-polarized light is used to follow the grain size, which is refined from 8 mm to 1 mm for as-cast samples and is maintained during thermal aging. Intermetallic compounds (IMCs) present inside the bulk Sn matrix affect the mechanical properties of the SAC alloys. Due to high-temperature exposure, these IMCs grow and hence their impact on mechanical properties becomes more significant. This growth is followed by scanning electron microscopy, and energy-dispersive spectroscopy is used for elemental mapping of each phase. A significant refinement in the average size of IMCs of up to 40% is identified for the as-cast samples, and the coarsening rate of these IMCs is slowed by up to 70% with no change in the interparticle spacing. Yield stress and tensile strength are determined through tensile testing at 20°C for as-cast samples and after thermal aging at 150°C for 100 h and 200 h. Both yield stress and tensile strength are increased by up to 20% by minute lanthanum doping.

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Section: Particle Sizementioning

confidence: 97%

Impact of Thermal Aging on the Microstructure Evolution and Mechanical Properties of Lanthanum-Doped Tin-Silver-Copper Lead-Free Solders

Sadiq

Pesci

Cherkaoui

2013

Journal of Elec Materi

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“…As we shall argue below, initial precipitate spacings in SAC305 tend to be small enough to prevent the coalescence and rotation of the dislocation cells unless the strain ranges, and thus the stresses, are quite high. This means that a relatively high dislocation density is rapidly established, but nothing further happens until cycling-induced precipitate coarsening 39 leads to a sufficiently large spacing.…”

Section: Effects Of Precipitatesmentioning

confidence: 99%

“…39,48,50 Here, _ e in is the inelastic shear strain rate in the ramp, C Ag is the equilibrium solubility of Ag in the solder, D Ag is the diffusivity of Ag in the fastest direction in Sn, T is the absolute temperature, and K' and u o are constants. Kumar et al 50 calculated the effective ramp time, t ramp , from an integral over the dependent coarsening rate in the ramp.…”

Section: Precipitate Coarseningmentioning

confidence: 99%

A Mechanistic Thermal Fatigue Model for SnAgCu Solder Joints

Børgesen

Wentlent

Hamasha

et al. 2018

Journal of Elec Materi

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The present work offers both a complete, quantitative model and a conservative acceleration factor expression for the life span of SnAgCu solder joints in thermal cycling. A broad range of thermal cycling experiments, conducted over many years, has revealed a series of systematic trends that are not compatible with common damage functions or constitutive relations. Complementary mechanical testing and systematic studies of the evolution of the microstructure and damage have led to a fundamental understanding of the progression of thermal fatigue and failure. A special experiment was developed to allow the effective deconstruction of conventional thermal cycling experiments and the finalization of our model. According to this model, the evolution of damage and failure in thermal cycling is controlled by a continuous recrystallization process which is dominated by the coalescence and rotation of dislocation cell structures continuously added to during the hightemperature dwell. The dominance of this dynamic recrystallization contribution is not consistent with the common assumption of a correlation between the number of cycles to failure and the total work done on the solder joint in question in each cycle. It is, however, consistent with an apparent dependence on the work done during the high-temperature dwell. Importantly, the onset of this recrystallization is delayed by pinning on the Ag 3 Sn precipitates until these have coarsened sufficiently, leading to a model with two terms where one tends to dominate in service and the other in accelerated thermal cycling tests. Accumulation of damage under realistic service conditions with varying dwell temperatures and times is also addressed.

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“…Recently, there have been a number of publications that describe new creep constitutive models for near-ternary eutectic SnAgCu alloy. Dutta et al 1,2 developed a microstructurally adaptive creep model, which accounts for the effects of microstructural changes due to aging on the creep response of solder joints, and is capable of adjusting itself as solder joint microstructures evolve during service. Song et al 3,4 and Hua 5 discovered that the stress exponent has significantly different values between the low and high stress regimes.…”

Section: Introductionmentioning

confidence: 99%