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.

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.

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.

Effect of Aggregate on Drying Shrinkage of Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 701-708 ◽  
Author(s):  
Ru Mu ◽  
Wen Ling Tian ◽  
Yong Gang Guo
Keyword(s):  
Cement Paste ◽  
Volume Fraction ◽  
Drying Shrinkage ◽  
Moisture Diffusion ◽  
Moisture Loss ◽  
Normal Concrete ◽  
New Model ◽  
Model Code

A modified version of an existing drying shrinkage model developed by the authors is proposed which incorporates the influence of the aggregate on the process of shrinking. Whereas it is traditionally thought that the aggregate restrains the deformation of the cement paste and hence the shrinkage of the concrete, in this paper, the effect of aggregate on shrinkage is better represented by considering the effect of the aggregate on moisture diffusion. It is suggested that the presence of the aggregate modifies the diffusion of moisture which governs the moisture loss and hence the drying of concrete. Also, as the volume fraction of the aggregate in a normal concrete is about 75% or more, the shrinkage of the cement paste is ‘diluted’ by the aggregate in the concrete. Taking into account these effects, this new diffusion based shrinkage model has been proposed. To assess the accuracy of the new model the shrinkage of two concrete mixes is predicted and compared with the measured shrinkage of these mixes. Comparisons are also drawn with the shrinkage predicted using the Model Code 1990 (MC90). It was observed that the new model proposed here predicts the shrinkage of the concrete mixes more accurately than the MC90 model, particularly at early ages.

Influence of moisture concentration and hydrophobic material on induced stress in FCBGA package under reflow

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Elwin Heng ◽  
Mohd Zulkifly Abdullah
Keyword(s):  
Reflow Process ◽  
Test Vehicle ◽  
Moisture Concentration ◽  
Reflow Soldering ◽  
Content Type ◽  
Soldering Process ◽  
Induced Stress ◽  
Microelectronics Industry ◽  
Hydrophilic Materials ◽  
Hydrophobic Material

Purpose This paper focuses on the fluid-structure interaction (FSI) analysis of moisture induced stress for the flip chip ball grid array (FCBGA) package with hydrophobic and hydrophilic materials during the reflow soldering process. The purpose of this paper is to analyze the influence of moisture concentration and FCBGA with hydrophobic material on induced pressure and stress in the package at varies times. Design/methodology/approach The present study analyzed the warpage deformation during the reflow process via visual inspection machine (complied to Joint Electron Device Engineering Council standard) and FSI simulation by using ANSYS/FLUENT package. The direct concentration approach is used to model moisture diffusion and ANSYS is used to predict the Von-Misses stress. Models of Test Vehicle 1 (similar to Xie et al., 2009b) and Test Vehicle 2 (FCBGA package) with the combination of hydrophobic and hydrophilic materials are performed. The simulation for different moisture concentrations with reflows process time has been conducted. Findings The results from the mechanical reliability study indicate that the FSI analysis is found to be in good agreement with the published study and acceptable agreement with the experimental result. The maximum Von-Misses stress induced by the moisture significantly increased on FCBGA with hydrophobic material compared to FCBGA with a hydrophilic material. The presence of hydrophobic material that hinders the moisture desorption process. The analysis also illustrated the moisture could very possibly reside in electronic packaging and developed beyond saturated vapor into superheated vapor or compressed liquid, which exposed electronic packaging to higher stresses. Practical implications The findings provide valuable guidelines and references to engineers and packaging designers during the reflow soldering process in the microelectronics industry. Originality/value Studies on the influence of moisture concentration and hydrophobic material are still limited and studies on FCBGA package warpage under reflow process involving the effect of hydrophobic and hydrophilic materials are rarely reported. Thus, this study is important to effectively bridge the research gap and yield appropriate guidelines in the microelectronics industry.

Packaging Materials for 2.5/3D Technology

2013 ◽  
Vol 2013 (1) ◽  
pp. 000276-000284 ◽  
Author(s):  
Brian Schmaltz
Keyword(s):  
High Reliability ◽  
Low Cost ◽  
High Yield ◽  
Wafer Level ◽  
Reflow Process ◽  
Thermal Compression ◽  
Conductive Films ◽  
Cu Pillar ◽  
Advanced Packaging ◽  
Capillary Underfill

The age of advanced mobile devices is on the direct horizon, are we ready for it? Less power consumption, faster processing, high reliability, high yield, low cost are words engineers are all too familiar with. 2.5/3D utilizing interposer technology, Thru Silicon Via (TSV), sub-50μm die thickness are a few of the latest techniques engineers use to solve these issues. As technology progresses to smaller process generations, new packaging applications are being demanded. The standard solder reflow process is being pushed by advancements in Cu pillar bumps, thermal compression bonding (TCB) and wafer level / pre-applied materials. This presentation will centralize around the latest advancements in NAMICS Materials for Advanced Packaging Technology; Capillary Underfill (CUF), Pre-Applied Material, Non-Conductive Paste (NCP), Non-Conductive Films (NCF).

A Note on the Normalized Approach to Simulating Moisture Diffusion in a Multimaterial System Under Transient Thermal Conditions Using ansys 14 and 14.5

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Dapeng Liu ◽  
Seungbae Park
Keyword(s):  
Material Property ◽  
Thermal Conditions ◽  
Moisture Diffusion ◽  
Electronic Components ◽  
Current Version ◽  
Temperature Dependent ◽  
Moisture Concentration ◽  
Hygroscopic Swelling ◽  
Packaging Industry ◽  
Transient Thermal

Moisture can have significant effects on the performance and reliability of electronic components. Accurately simulating moisture diffusion is important for designers and manufacturers to obtain a realistic reliability evaluation. Beginning with version 14, ansys is capable of simulating diffusion and related behaviors, such as hygroscopic swelling, with newly developed elements. However, a normalized approach is still required to deal with the discontinuity of concentrations at the material boundaries, and normalization of the moisture concentration in transient thermal conditions is tricky. Case studies have shown that normalizing the moisture concentration with respect to a time- or temperature-dependent material property will lead to erroneous results. This paper re-addresses the issues of performing diffusion simulations under transient thermal conditions and more general anisothermal conditions (temporally and spatially), and suggests an easy-to-use approach to cope with the limitations of the current version for users in the electronic packaging industry.

Experimental Research on the Influence of Humidity on the Moisture Diffusion in Cement-Based Materials

2010 ◽  
Vol 168-170 ◽  
pp. 1806-1809
Author(s):  
Qing Su ◽  
Tie Jun Zhao ◽  
Fan Xiao ◽  
Tao Cui
Keyword(s):  
Moisture Diffusion ◽  
Moisture Loss ◽  
River Sand ◽  
Moisture Migration ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Sea Sand ◽  
Cement Based Materials ◽  
Main Factor

The migration of ion dissolved in water is known to be main factor inducing the deterioration of porous cement-based materials in aggressive environment. Long-term tests have been carried to study the moisture diffusion in mortar with water cement ratio of 0.5 and 0.6 in different humidity, and then the inverse analysis has been done to determine the moisture diffusion coefficient D. The results indicate that the bigger water cement ratio, the faster moisture migrating in same humidity, and the moisture migration process is longer for the mortar under lower humidity. Furthermore, the results of controlled experiments carried on mortar specimens with sea sand show that the moisture migration is longer for sea sand mortar than that of river sand, and the moisture loss is bigger.

scholarly journals A Novel Moisture Diffusion Modeling Approach Using Finite Element Analysis

Electronics ◽  
2018 ◽  
Vol 7 (12) ◽  
pp. 438 ◽  
Author(s):  
Cagan Diyaroglu ◽  
Erdogan Madenci ◽  
Selda Oterkus ◽  
Erkan Oterkus
Keyword(s):  
Finite Element ◽  
Surface Effect ◽  
Moisture Diffusion ◽  
Current Approach ◽  
Numerical Results ◽  
Solution Technique ◽  
Material System ◽  
Diffusion Modeling ◽  
Element Analysis ◽  
Moisture Concentration

In this study, a novel wetness and moisture concentration analysis approach is presented. A finite element method is utilized for the solution technique mainly using thermal and surface effect elements. Numerical results obtained from the current approach are compared against other existing finite element-based solutions and the newly introduced peridynamics theory. For numerical analysis, a reflow soldering stage is simulated for a multi-material system with time-dependent saturated moisture concentrations. Different solubility activation energies and temperature conditions are considered. Numerical results demonstrate that the developed methodology can make accurate predictions under different conditions and it is more general than some other existing models which are limited to certain conditions.

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