Measurement and Simulation of Moisture Induced Die Stresses in Flip Chip on Laminate Assemblies

2015 ◽  
Author(s):  
Quang Nguyen ◽  
Jordan C. Roberts ◽  
Jeffrey C. Suhling ◽  
Richard C. Jaeger ◽  
Pradeep Lall
Keyword(s):  
Flip Chip ◽  
Moisture Absorption ◽  
Moisture Diffusion ◽  
Shear Stresses ◽  
Experimental Measurements ◽  
Normal Stresses ◽  
Long Term Storage ◽  
Stress Changes ◽  
Term Storage

In this work, an investigation has been performed on hygrothermally induced die stresses in flip chip assemblies caused by moisture absorption by the underfill encapsulant. Silicon test chips were first applied to perform a variety of measurements of moisture and thermally induced die stresses in flip chip on laminate assemblies. The sample die stresses were first measured after underfill encapsulation and cure, and then subsequently after long term storage (10 years) at room temperature and ambient humidity. The assemblies were then exposed to and 85 °C and 85% RH high humidity harsh environment for various durations, and the die stresses were evaluated as a function of the exposure time. Finally, reversibility tests were conducted to see whether the effects of moisture uptake were permanent. After long term storage, the experimental measurements showed that the normal stresses in the flip chip die relaxed significantly, while the shear stresses exhibited only small variations. In addition, the 85/85 hygrothermal exposure had strong effects, generating tensile die normal stress changes of up to 30 MPa in the flip chip assemblies. Thus, the initial compressive die normal stresses due to flip chip assembly were found to relax significantly during the moisture exposure. Upon fully redrying, it was observed that the moisture-induced stress changes were fully recovered. The results of the experimental measurements were subsequently correlated with predictions from finite element numerical simulations. When performing moisture diffusion modeling, the conventional method is to use a thermal analogy based on the similarity of governing equations of heat transfer and moisture diffusion. However, this method has some drawbacks including giving incorrect results when dealing with time- and temperature-dependent problems or discontinuities in the moisture concentrations at material boundaries. In this study, we have used a new feature in ANSYS v14 to perform coupled multi-physics simulations of the moisture diffusion process without the aforementioned limitations. The simulation results were found to show strong correlations with experimental measurements.

Characterization of Die Stresses in Plastic Packages Subjected to Moisture and Thermal Exposures

2015 ◽  
Author(s):  
Quang Nguyen ◽  
M. Kaysar Rahim ◽  
Jordan C. Roberts ◽  
Jeffrey C. Suhling ◽  
Richard C. Jaeger
Keyword(s):  
Normal Stress ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Long Term Storage ◽  
Plastic Packages ◽  
Stress Changes ◽  
Die Stress ◽  
Test Chips ◽  
Term Storage

Stress sensing test chips are a powerful tool for measuring in-situ stresses in electronic packages. In this study, we have applied (111) silicon test chips to perform a variety of measurements of die stresses in plastic packages. In particular, stresses were characterized in 240 pin Quad Flat Packs (QFPs) subjected to various thermal and moisture loadings. The utilized 10 × 10 mm sensor chips incorporated optimized eight-element piezoresistive rosettes that were capable of measuring the complete state of stress at the die surface (including the interfacial shear stresses). The fabricated test chips were initially used to measure die stresses in the QFPs after molding and post mold bake. Measurement results were correlated with finite element simulations of the molding process. Subsequently, the effects of thermal cycling on the measured die stress distributions for selected packages were investigated. After these initial measurements, the samples were stored at room temperature and ambient humidity for 17 years. The samples were then re-measured after this long term storage to evaluate the degree of die stress relaxation that had occurred. Several packages were then exposed to a harsh high temperature and high humidity environment (85 C, 85% RH) for various time durations, and allowed to absorb moisture. The die stresses at several locations were characterized as a function of time during the hygrothermal exposure. The weight variations in each sample were also measured during the 85/85 exposure to gauge the moisture uptake, and reversibility tests were conducted to see whether the effects of moisture uptake were permanent. Using these measurements and numerical simulations, valuable insight has been gained on moisture induced failure phenomena in plastic packages. Good agreement was found between the predicted and measured die normal stress distributions occurring after molding of the QFP. The magnitudes of the in-plane normal and shear stresses were found to have decreased by up to 30% after moderate levels of thermal cycling. After long term storage, the experimental measurements showed that the die normal stresses in the QFPs relaxed significantly (up to 40%), while the die shear stresses exhibited only small variations. In addition, the 85/85 hygrothermal exposures had strong effects, generating tensile die normal stress changes of up to 130 MPa. Upon fully redrying in reversibility tests, it was observed that the moisture-induced normal stress changes were not recovered. Good correlations were observed between the variations of sample weight (increases in moisture content) and the variations of the die normal and shear stress changes.

Study on Mechanical Behavior and Long-term Storage Reliability of Micro Flip Chip Mixed Solder Joints

2021 ◽  
Author(s):  
Shuang Xie ◽  
Huidong Wen ◽  
Yong Wang ◽  
Pengrong Lin ◽  
Xiaochen Xie ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Flip Chip ◽  
Solder Joints ◽  
Long Term Storage ◽  
Term Storage

Modelling of Moisture Movement in Wood during Outdoor Storage

2001 ◽  
Vol 6 (2) ◽  
pp. 3-14 ◽  
Author(s):  
R. Baronas ◽  
F. Ivanauskas ◽  
I. Juodeikienė ◽  
A. Kajalavičius
Keyword(s):  
Experimental Data ◽  
Finite Difference ◽  
Climatic Conditions ◽  
Two Dimensional ◽  
Moisture Movement ◽  
Finite Difference Technique ◽  
Long Term Storage ◽  
Space Formulation ◽  
Term Storage

A model of moisture movement in wood is presented in this paper in a two-dimensional-in-space formulation. The finite-difference technique has been used in order to obtain the solution of the problem. The model was applied to predict the moisture content in sawn boards from pine during long term storage under outdoor climatic conditions. The satisfactory agreement between the numerical solution and experimental data was obtained.

Trehalose: a cryoprotectant that enhances recovery and preserves function of human pancreatic islets after long-term storage

Diabetes ◽  
1997 ◽  
Vol 46 (3) ◽  
pp. 519-523 ◽  
Author(s):  
G. M. Beattie ◽  
J. H. Crowe ◽  
A. D. Lopez ◽  
V. Cirulli ◽  
C. Ricordi ◽  
...  
Keyword(s):  
Pancreatic Islets ◽  
Human Pancreatic Islets ◽  
Long Term Storage ◽  
Term Storage

Humidity reliability of commercial flash memories for long-term storage

2020 ◽  
Vol 59 (SL) ◽  
pp. SLLC01 ◽  
Author(s):  
Tomoki Murota ◽  
Toshiki Mimura ◽  
Ploybussara Gomasang ◽  
Shinji Yokogawa ◽  
Kazuyoshi Ueno
Keyword(s):  
Flash Memories ◽  
Long Term Storage ◽  
Term Storage

MODERN PROBLEMATICS AND ANALYSIS OF EFFICIENCY OF APPLICATION OF DIFFERENT APPROACHES TO DESTRUCTION OF INFORMATION ON MAGNETIC MEDIA

2019 ◽  
Vol 2 (12) ◽  
pp. 154-164
Author(s):  
O. Semenenko ◽  
O. Vodchyts ◽  
V. Koverga ◽  
R. Lukash ◽  
O. Lutsenko
Keyword(s):  
Armed Forces ◽  
Information Storage ◽  
Storage Device ◽  
Magnetic Media ◽  
Long Term Storage ◽  
Physical Impact ◽  
And Storage ◽  
Term Storage

The introduction and active use of information transmission and storage systems in the Ministry of Defense (MoD) of Ukraine form the need to develop ways of guaranteed removal of data from media after their use or long-term storage. Such a task is an essential component of the functioning of any information security system. The article analyzes the problems of guaranteed destruction of information on magnetic media. An overview of approaches to the guaranteed destruction of information on magnetic media of different types is presented, and partial estimates of the effectiveness of their application are given by some generally accepted indicators of performance evaluation. The article also describes the classification of methods of destruction of information depending on the influence on its medium. The results of the analysis revealed the main problems of application of software methods and methods of demagnetization of the information carrier. The issue of guaranteed destruction of information from modern SSD devices, which are actively used in the formation of new systems of information accumulation and processing, became particularly relevant in the article. In today's conditions of development of the Armed Forces of Ukraine, methods of mechanical and thermal destruction are more commonly used today. In the medium term, the vector of the use of information elimination methods will change towards the methods of physical impact by the pulsed magnetic field and the software methods that allow to store the information storage device, but this today requires specialists to develop new ways of protecting information in order to avoid its leakage.

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