Dual stage modeling of moisture absorption and desorption in epoxy mold compounds

Placette, Mark D.; Fan, Xuejun; Zhao, Jiajun; Edwards, D.

doi:10.1016/j.microrel.2012.03.008

Cited by 77 publications

(53 citation statements)

References 14 publications

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“…D 1eff and D 2eff represent, respectively, the effective diffusion coefficients at the initial and final phases. M 1 ∞ and M 2 ∞ are the water gain at the saturation point corresponding, respectively, to the initial and final phases [24, 32, 33]. The water absorbed at the end of the process is given by

\begin{matrix} M_{\infty} = M_{1 \infty} + M_{2 \infty} . \end{matrix}

…”

Section: Methodsmentioning

confidence: 99%

Study of Water Absorption in RaffiaviniferaFibres from Bandjoun, Cameroon

Tagne

Njeugna

Fogue

et al. 2014

The Scientific World Journal

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The study is focused on the water diffusion phenomenon through the Raffia vinifera fibre from the stem. The knowledge on the behavior of those fibres in presence of liquid during the realization of biocomposite, is necessary. The parameters like percentage of water gain at the point of saturation, modelling of the kinetic of water absorption, and the effective diffusion coefficient were the main objectives. Along a stem of raffia, twelve zones of sampling were defined. From Fick's 2nd law of diffusion, a new model was proposed and evaluated compared to four other models at a constant temperature of 23°C. From the proposed model, the effective diffusion coefficient was deduced. The percentage of water gain was in the range of 303–662%. The proposed model fitted better to the experimental data. The estimated diffusion coefficient was evaluated during the initial phase and at the final phase. In any cross section located along the stem of Raffia vinifera, it was found that the effective diffusion coefficient increases from the periphery to the centre during the initial and final phases.

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\begin{matrix} M_{\infty} = M_{1 \infty} + M_{2 \infty} . \end{matrix}

…”

Section: Methodsmentioning

confidence: 99%

Study of Water Absorption in RaffiaviniferaFibres from Bandjoun, Cameroon

Tagne

Njeugna

Fogue

et al. 2014

The Scientific World Journal

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“…Figure 1 and Figure 2 illustrate the local environments compared to the far field environment. The relative humidity (RH) is the percent of saturation humidity, generally defined and calculated in relation to saturated vapor density at the given temperature as follows (1) Or, the RH can also be approximately defined as the percent of saturated partial vapor pressure, as follows (2) This is because that vapor density can be approximated from the vapor pressure by the ideal gas law [3,[5][6][7][8][9][10][11][12][13][14][15][16][17]. The saturated vapor density and vapor pressure of water are given in the Appendix for convenience.…”

Section: Relative Humidity and Saturated Moisture Concentration In Mamentioning

confidence: 99%

Effect of temperature gradient on moisture diffusion in high power devices and the applications in LED packages

Fan

Yuan

2013

2013 IEEE 63rd Electronic Components and Technology Conference

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High power electronic devices create hot spots, which give rise to the junction temperature significantly higher than the ambient temperature. This induces a situation that the moisture diffusion from environment to device is in the direction against temperature gradient direction. In addition, far field relative humidity is different from the environment surrounding the packaged devices. In this paper, two mechanisms of moisture transport are studied. First, the localized relative humidity related to the far field ambient environment is investigated. Second, moisture diffusion in the presence of temperature gradient inside package is studied. Several scenarios are investigated with the use of an LED package as example. IntroductionDriven by the demand in compact and lightweight products, there has been a trend for ongoing miniaturization of packages. Similar trends can be observed in the development of LED packages [1,2]. One of the critical concerns is the reliability of such packages under humidity condition [3].High power electronic devices create hot spots, which give rise to the junction temperature significantly higher than the ambient temperature. This creates the temperature gradient, not only inside electronic packages, but also the air environment that surrounds the packaged devices. According to the reliability method developed by Intel [4], it has been conceived that the hot spots in high power electronic devices, such as in CPU devices, will have localized "drying" or a reduction in relative humidity (RH) in a micro-environment. Consequently, it is predicted that the devices at on condition will have longer life than that at off condition under the same environmental humidity conditions.In this paper, we divide the problem into two parts: moisture transport in air and solids, respectively. In air, assuming that the partial moisture pressure is in equilibrium, the relationship between the local relative humidity and the far field relative humidity can be derived. The local relative humidity and temperature can then be used as boundary conditions for solving moisture diffusion in solids. Next, the moisture diffusion in the presence of temperature gradient is investigated in package. Since thermal diffusion in solids is much greater than the moisture diffusivity, the temperature field can be solved with a steady state solution, while the moisture diffusion is treated as a subsequent transient stage analysis. As an example, the above methodology is applied to a mid-high power LED package.

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“…Those models provide good agreement with experimental data, but introduce additional parameters and mathematical complexity. Alternatively, the second stage can be also modeled in Fickian terms for mathematical simplicity and comparability [4,11]. It should be noted that the second stage (C 2 ) is an irreversible, non-Fickian process.…”

Section: Mathematical Modelsmentioning

confidence: 99%

“…It is noted that in Equation (4), if C r is known, equation (4) becomes a single-stage Fickian-type diffusion, so-called modified Fickian diffusion model in [4,11].…”

Section: Mathematical Modelsmentioning

confidence: 99%

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Finite element modeling of anomalous moisture diffusion with dual stage model

Fan

Nagaraj

2012

2012 IEEE 62nd Electronic Components and Technology Conference

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In this paper, finite element modeling of anomalous moisture diffusion using commercial finite element code is developed. The modeling method and numerical implementation is based on a dual stage model with both stages described by Fickian terms mathematically. The method is also extended to desorption process at reflow, in which the permanently trapped moisture content is a function of temperature. This paper details the finite element modeling implementation steps for both moisture absorption and desorption. The results are compared to the analytical solutions, and are also compared to the experimental data. A single script using ANSYS APDL is developed for the whole process including absorption and desorption phases.

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Dual stage modeling of moisture absorption and desorption in epoxy mold compounds

Cited by 77 publications

References 14 publications

Study of Water Absorption in RaffiaviniferaFibres from Bandjoun, Cameroon

Study of Water Absorption in RaffiaviniferaFibres from Bandjoun, Cameroon

Effect of temperature gradient on moisture diffusion in high power devices and the applications in LED packages

Finite element modeling of anomalous moisture diffusion with dual stage model

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