Modeling of Moisture Diffusion and Whole-Field Vapor Pressure in Plastic Packages of IC Devices

2010 ◽  
pp. 91-112 ◽  
Author(s):  
X. J. Fan ◽  
T.Y. Tee ◽  
X.Q. Shi ◽  
B. Xie
Keyword(s):  
Vapor Pressure ◽  
Moisture Diffusion ◽  
Plastic Packages

Moisture Diffusion in Epoxy Molding Compounds Filled With Particles

1998 ◽  
Vol 123 (1) ◽  
pp. 47-51 ◽  
Author(s):  
M. Uschitsky ◽  
E. Suhir
Keyword(s):  
Integrated Circuits ◽  
Thermal Stresses ◽  
Experimental Studies ◽  
Moisture Sorption ◽  
Moisture Diffusion ◽  
Filler Concentration ◽  
Mechanical Reliability ◽  
High Concentration ◽  
Molding Compounds ◽  
Plastic Packages

Mechanical reliability of epoxy molding compounds in plastic packages of integrated circuits (IC) is greatly affected by the compound ability to absorb moisture. Accordingly, the objective of the study is to evaluate the effect of moisture sorption on the mechanical properties of the compound. Experimental studies were conducted to evaluate the moisture diffusion in compounds with different, from moderate to high, concentration of silica and alumina nitride fillers. The weight-gained analysis indicated that the moisture diffusion was of non-Fickian type and depended mainly on the specimen’s relative humidity and the filler concentration. We found that although the hygro-thermal stresses, caused by moisture diffusion, were relatively low, such diffusion led to an appreciable decrease in the compound’s strength. Moisture diffusion can result also in a substantial increase in the material’s plasticity. The obtained results can be helpful in the analysis of the mechanical behavior of molding compounds employed in electronic packaging. These results can be used to better understand and to improve the reliability of plastic packages of IC devices.

A Combined Analysis of Moisture Diffusion with Interface Fracture Mechanics on the Interface Delamination in the Plastic IC Packages During Reflow Soldering

1998 ◽  
Vol 515 ◽  
Author(s):  
Y. B. Park ◽  
Jin Yu
Keyword(s):  
Vapor Pressure ◽  
Thermal Loading ◽  
Moisture Diffusion ◽  
Interface Fracture ◽  
Vapor Pressures ◽  
Crack Face ◽  
Reflow Soldering ◽  
Molding Compound ◽  
Interface Delamination ◽  
Small Cracks

ABSTRACTThe popcorn cracking phenomenon of plastic IC packages during the reflow soldering was investigated by conducting the stress analysis of heat transfer and moisture diffusion. Vapor pressures at delaminated interfaces between the die pad and EMC(Epoxy molding compound) were calculated and mechanistic parameters such as energy release rate, stress intensity factor and phase angle were derived under various loading conditions; thermal, crack face vapor pressure and mixed loadings. It was shown that thermal loading was the main driving force for crack propagation for small cracks lengths, but vapor pressure loading played more significant role as the crack extended.

Comprehensive Hygro-Thermo-Vapor Pressure Model for CMOS Image Sensor

2009 ◽  
Vol 419-420 ◽  
pp. 493-496
Author(s):  
Hsiang Chen Hsu ◽  
Li Ming Chu ◽  
Lih Shan Chen ◽  
Shen Li Fu
Keyword(s):  
Vapor Pressure ◽  
Moisture Absorption ◽  
Three Dimensional ◽  
Moisture Diffusion ◽  
Cmos Image Sensor ◽  
Image Sensor ◽  
Mechanical Analysis ◽  
Element Analysis ◽  
Swelling Properties ◽  
Moisture Expansion

A combined effect of moisture diffusion, heat transfer, and hygro-thermo-vapor pressure modeling for pre-mold QFN CMOS Image Sensor (CIS) package has been developed in this study. Hygroscopic swelling properties such as saturation, coefficient of moisture expansion (CME) and activation energy can be extracted through TMA (Thermal Mechanical Analysis) and TGA (Thermal Gravitational Analysis) instruments. Fick’s second law of transient diffusion is solved by using finite element analysis (FEA) to evaluate the overall moisture distributions. With obtained experimental data, a three-dimensional FEA CIS model using the “thermal-wetness” technique is developed to predict the moisture absorption, moisture desorption, temperature distributions, hygro-thermo-vapor pressure mechanical coupled effect and the residual stress distributions at JEDEC pre-conditioning standard JESD22-A120.

Direct Concentration Approach of Moisture Diffusion and Whole-Field Vapor Pressure Modeling for Reflow Process—Part II: Application to 3D Ultrathin Stacked-Die Chip Scale Packages

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
B. Xie ◽  
X. J. Fan ◽  
X. Q. Shi ◽  
H. Ding
Keyword(s):  
Vapor Pressure ◽  
Failure Rate ◽  
Moisture Diffusion ◽  
Bottom Layer ◽  
Moisture Loss ◽  
Substrate Thickness ◽  
Wafer Level ◽  
Reflow Process ◽  
Film Rupture ◽  
Moisture Concentration

In the present study, the direct concentration approach (DCA) and the whole-field vapor pressure model developed in Part I of this work (Xie et al., 2009 “Direct Concentration Approach of Moisture Diffusion and Whole Field Vapor Pressure Modeling for Reflow Process: Part I–Theory and Numerical Implementation,” ASME J. Electron. Packag., 131, p. 031010) is applied to 3D ultrathin stacked-die chip scale packages to investigate wafer-level die-attach film cohesive failures during the reflow process. Oversaturation, which refers to the film that absorbs more moisture when reflow process begins, is observed using the DCA. The modeling results suggest that the moisture transport and escape through the substrate during the reflow is responsible for the film rupture. A small reduction in substrate thickness could result in a significant decrease in moisture concentration and vapor pressure in bottom layer film and therefore reduce failure rate greatly. A slight improvement in reflow profile while still meeting specification allows a significant amount of moisture loss during the reflow; hence failure rate could also be reduced greatly. The mechanism of soft film rupture at reflow due to moisture is discussed in detail. The simulation results are consistent with the published experimental data.

Strength Evaluation of Plastic Packages During Solder Reflow Process Using Stress Intensity Factors of V-Notch

2003 ◽  
Vol 125 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Toru Ikeda ◽  
Isao Arase ◽  
Yuya Ueno ◽  
Noriyuki Miyazaki ◽  
Nobutaka Ito ◽  
...  
Keyword(s):  
Stress Intensity ◽  
Vapor Pressure ◽  
Stress Intensity Factors ◽  
Moisture Absorption ◽  
Evaluation Technique ◽  
Reflow Process ◽  
Intensity Factors ◽  
Moisture Concentration ◽  
Plastic Packages ◽  
Solder Reflow

A crack initiated from a V-notch corner in the molding resin, such as a corner of die pad, is one of the main causes of the failure in plastic packages. The stress intensity factors of the asymptotic solution of a corner of jointed dissimilar materials are utilized for the evaluation of a solder reflow crack in a quad flat package (QFP). First, we estimate the critical vapor pressure, which causes a crack from a corner in the molding resin, using the critical stress intensity factor of a V-notch corner. This critical factor was measured by V-notched three-point bending tests and the displacement extrapolation method along with the three dimensional (3-D) finite element method (FEM). Moisture concentration in the QFP after absorption is analyzed, and vapor pressure caused by the solder reflow process is estimated. The critical moisture absorption time, which results in crack occurrence during the solder reflow process, can be predicted using this evaluation technique. Furthermore, we perform infrared solder reflow tests of the QFP for verifying the present failure evaluation technique.

Direct Concentration Approach of Moisture Diffusion and Whole-Field Vapor Pressure Modeling for Reflow Process—Part I: Theory and Numerical Implementation

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
B. Xie ◽  
X. J. Fan ◽  
X. Q. Shi ◽  
H. Ding
Keyword(s):  
Vapor Pressure ◽  
Moisture Diffusion ◽  
Field Variable ◽  
Electronic Packages ◽  
Numerical Implementation ◽  
Reflow Process ◽  
Moisture Concentration ◽  
Normalization Methods ◽  
Temperature State ◽  
Moisture State

Moisture concentration is discontinuous at interfaces when two materials, which have different saturated moisture concentrations, are joined together. In order to perform moisture diffusion modeling in a multimaterial system such as electronic packages, normalization methods have been commonly used to remove the discontinuity of moisture concentration at interfaces. However, such treatments cannot be extended to a reflow process, in which ambient temperature and/or humidity vary with time. This paper develops a direct concentration approach, with which the moisture concentration is used as a field variable directly. Constraint equations are applied to meet the interface continuity requirements. Further in this paper, a simplified vapor pressure model based on a multiscale analysis is developed. The model considers the phase change in moisture, and links the macroscopic moisture concentration to the moisture state at a microscopic level. This model yields the exact same results with the original vapor pressure model (Fan, et al., 2005, “A Micromechanics Based Vapor Pressure Model in Electronic Packages,” ASME J. Electron. Packag., 127(3), pp. 262–267). The new model does not need to relate to a reference temperature state. Numerical implementation procedures for calculating moisture concentration and ensuing vapor pressure, which are coupled with temperature analysis, are presented in this paper.

On Water Behavior Inside and Around a Void at Polymer Interface

2006 ◽  
Author(s):  
Changsoo Jang ◽  
Seungbae Park
Keyword(s):  
Vapor Pressure ◽  
Liquid Water ◽  
Polymeric Materials ◽  
Moisture Diffusion ◽  
Material Interfaces ◽  
Polymer Interface ◽  
Reflow Temperature ◽  
Water Behavior ◽  
High Vapor ◽  
Water Accumulation

As the use of polymeric materials is increasing in microelectronics industry, the failure issues related to moisture are getting more popular. Moisture absorbed into the electronic package causes interfacial delamination through the synergetic effects of hygro-thermo-mechanical stresses and degradation of adhesion strength. It also results in catastrophic crack propagation during reflow process, called pop-coming. Vapor pressure inside preexisting voids at material interfaces is known to be a dominant driving force of this phenomenon. In order to explain vapor pressure generation at high reflow temperature, researchers so far have been presuming two mechanisms: liquid water boiling and quick moisture diffusion. In spite of the importance as a basis of the failure analysis, there has been little focus on the mechanism of liquid water accumulation, more exactly, high vapor pressure generation inside voids. In this study various known mechanisms of liquid water formation inside a void at polymer interface are reviewed. They include condensation, adsorption, capillary, and microfogging. As an alternative possibility, moisture diffusion around the void for a short reflow period is also assessed through numerical analysis.

Benzylamine Tartrate as an Organic Glass Substrate for Carbon Films by Evaporation

1970 ◽  
Vol 28 ◽  
pp. 484-485
Author(s):  
A. C. Faberge
Keyword(s):  
Vapor Pressure ◽  
Viscous Liquid ◽  
Glass Substrate ◽  
Room Temperature ◽  
Carbon Film ◽  
Carbon Films ◽  
Organic Glass ◽  
Spectroscopic Examination ◽  
Polymeric Substrates

Benzylamine tartrate (m.p. 63°C) seems to be a better and more convenient substrate for making carbon films than any of those previously proposed. Using it in the manner described, it is easy consistently to make batches of specimen grids as open as 200 mesh with no broken squares, and without individual handling of the grids. Benzylamine tartrate (hereafter called B.T.) is a viscous liquid when molten, which sets to a glass. Unlike polymeric substrates it does not swell before dissolving; such swelling of the substrate seems to be a principal cause of breakage of carbon film. Mass spectroscopic examination indicates a vapor pressure less than 10−9 Torr at room temperature.

Hydration Chamber for Jeolco 200 Kv Microscope

1970 ◽  
Vol 28 ◽  
pp. 542-543
Author(s):  
V. R. Matricardi ◽  
G. G. Hausner ◽  
D. F. Parsons
Keyword(s):  
Electron Microscope ◽  
Water Vapor ◽  
Vapor Pressure ◽  
Pressure Gradient ◽  
Room Temperature ◽  
List Type ◽  
Type Number ◽  
Equilibrium Vapor Pressure

In order to observe room temperature hydrated specimens in an electron microscope, the following conditions should be satisfied: The specimen should be surrounded by water vapor as close as possible to the equilibrium vapor pressure corresponding to the temperature of the specimen.The specimen grid should be inserted, focused and photo graphed in the shortest possible time in order to minimize dehydration.The full area of the specimen grid should be visible in order to minimize the number of changes of specimen required.There should be no pressure gradient across the grid so that specimens can be straddled across holes.Leakage of water vapor to the column should be minimized.

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