Advanced moisture diffusion model and hygro-thermo-mechanical design for flip chip BGA package

Tsai, Ming-Han; Hsu, Feng-Jui; Weng, Meng-Chieh; Hsu, Hsiang-Chen

doi:10.1109/icept.2009.5270573

Cited by 7 publications

(3 citation statements)

References 9 publications

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“…This Fickian behavior is expected, as observed in many epoxy/polymer moisture uptake experiments with weight measure [12], [13]; however, non-Fickian behavior has also been observed in the literature, especially in high-temperature environments, where a dual-stage diffusion model is used [14], [15], [16], [17], [18], [19]. The moisture saturation concentration (C sat ) that is obtained when the impedance of the sensors is stabilized is related to the ambient RH set by the environmental chamber, the solubility (S), and the saturated vapor pressure (P v,sat ).…”

Section: A Single Sensor Behaviorsupporting

confidence: 77%

Moisture Diffusion Inside the BEOL of an FC-PBGA Package

Vandier

Frémont

Drouin

2022

IEEE Trans. Compon., Packag. Manufact. Technol.

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Moisture diffusion into the back-end-of-line (BEOL) can be critical for the reliability of electronic devices. With the objective of studying moisture diffusion into critical areas, such as the silicon-organic substrate interfaces of a flip chip plastic ball grid array (FC-PBGA), a multitude of impedance sensors sensitive to moisture are integrated inside the BEOL of a 17 × 17 mm silicon die. The sensors are read by a dedicated custom circuit that allows accurate characterization of the moisture with in situ spatial measurements. This article presents the results obtained by the experimental acquisition system on the FC-PBGA module under a high-relative humidity (RH) level of up to 75%. This study shows the moisture behavior of the multiwalled carbon nanotube (MWCNT) sensors inside the BEOL during absorption and desorption. The behavior initially follows Fick's law, with a constant increase in the RH. For long-term tests of more than 400 h, an asymptotic behavior is observed; when the concentration of a sensor reaches a value close to saturation, a two-dimensional finite-difference method (2D FDM) is used to estimate the saturation value. Thanks to the large number of sensors distributed on the BEOL, we first detect, during an absorption test, an increase in the RH. This increase is due, first of all, to a lateral moisture front with a constant velocity of about 90 µm/h moving through the underfill. Then, after 30 h of storage, a more complex diffusion through the organic substrate occurs, affecting the BEOL.

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Section: A Single Sensor Behaviorsupporting

confidence: 77%

Moisture Diffusion Inside the BEOL of an FC-PBGA Package

Vandier

Frémont

Drouin

2022

IEEE Trans. Compon., Packag. Manufact. Technol.

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“…C sat can be also defined as the ratio of mass of maximum absorbed moisture (M ∞ ) at time of saturation to the volume of the material (V ) [7], [17] is given as…”

Section: A Moisture Diffusionmentioning

confidence: 99%

Analysis of Dynamic Moisture Diffusion in Packaging Materials During Steam Sterilization

George

Barrett

2015

IEEE Trans. Compon., Packag. Manufact. Technol.

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We present a model, verified by experiment, for predicting the moisture absorption and desorption of a range of plastic encapsulant and organic circuit board materials under both nonsaturated and supersaturated steam conditions. This paper was carried out as part of the development of embedded plastic-encapsulated modules (PEMs) for monitoring the internal atmosphere parameters of medical steam sterilizers (autoclaves). The rapid cycles of temperature, pressure, and humidity that are a feature of autoclave operation present unique challenges for the reliability of embedded PEMs. Analysis of moisture absorption and desorption in candidate encapsulant and circuit board materials was, therefore, required for prediction of both moisture ingress and of hygroscopic swelling. This analysis was carried out at three different temperature/humidity/pressure levels (85°C/85%RH/atmospheric, 121°C/100%RH/2 bar, and 134°C/100%RH/3 bar), while desorption was analyzed at both ambient temperature/pressure and in a vacuum oven (0.6 and 0.3 bar) at 85°C, 121°C, and 134°C. Interval weighing was used to monitor the moisture diffusion in the samples and to identify when saturation/desiccation was reached. The moisture diffusion coefficients and the saturated moisture concentrations of the materials were extracted from the test results and a model, verified by experiment, was developed to predict these values for any temperature and humidity combination between 85°C/85%RH and 134°C/100%RH. Measurements of hygroscopic swelling were also carried out as part of the analysis. This is believed to be the first detailed analysis of moisture diffusion in these types of materials over this range of parameters.

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“…In most of the literatures [1,2], Fick's second law is used to describe moisture diffusion behavior and corresponding numerical method is established. Moreover, many investigations show that moisture absorption in polymers can lead to dimensional expansion, and CME is proposed to numerically calculate interface stress for delamination issue induced by moisture [3].…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical study of moisture effect on warpage of plastic package

Chen

Zhou

et al. 2014

2014 Joint IEEE International Symposium on the Applications of Ferroelectric, International Workshop on Acoustic Transduction M

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In this paper, the moisture effect on the warpage of plastic package is studied through experimental and numerical method.Many investigations have proved that polymer materials can expand after absorbing moisture. And coefficient of moisture expansion (CME) is proposed to quantitatively describe polymer expansion caused by moisture. The plastic package consists of epoxy molding compound (EMC) and PCB, both of which can easily absorb moisture. Since different amounts of moisture absorption in different materials can lead to different expansions, warpage of plastic package can change after moisture absorption, even when the temperature keeps constant. Both the warpage and moisture are monitored during a series of processes. And the results show similar changing trend. The CME of EMC and BT core is tested through TGA/TMA method. It is found that the CME increases with temperature. Moisture diffusion simulation is used to determine the moisture concentration change of EMC and BT core during the ambient storage. The results combined with CME are used to calculate the warpage change caused by moisture during the ambient storage. The simulation results agree with the experiments, verifying the moisture effect on warpage.

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Advanced moisture diffusion model and hygro-thermo-mechanical design for flip chip BGA package

Cited by 7 publications

References 9 publications

Moisture Diffusion Inside the BEOL of an FC-PBGA Package

Moisture Diffusion Inside the BEOL of an FC-PBGA Package

Analysis of Dynamic Moisture Diffusion in Packaging Materials During Steam Sterilization

Experimental and numerical study of moisture effect on warpage of plastic package

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