A parametric study of thermal stress and analysis of creep strain under thermal cyclic loading in a hybrid Quad Flat Package

2020 ◽  
pp. 1-1
Author(s):  
D. Zhou ◽  
A.S.M.A. Haseeb ◽  
A. Andriyana ◽  
Yew Hoong Wong ◽  
M.F.M. Sabri ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Cyclic Loading ◽  
Creep Strain ◽  
Parametric Study ◽  
Quad Flat Package

scholarly journals Study on estimation of creep behaviour of concrete at early age considering temperature effect

2019 ◽  
Vol 289 ◽  
pp. 10010
Author(s):  
Kayo Ohashi ◽  
Jun-ichi Arai ◽  
Toshiaki Mizobuchi
Keyword(s):  
Thermal Stress ◽  
Temperature Effect ◽  
Creep Strain ◽  
Prediction Accuracy ◽  
Creep Behaviour ◽  
Test Method ◽  
Control Measures ◽  
Experimental Result ◽  
Early Age ◽  
And Control

Clarifying the creep behaviour of concrete at early age not only improves the accuracy of temperature stress analysis but also contributes to prediction accuracy and control measures in cracks caused by thermal stress. However, most past researches on creep behaviour were investigated after 28 days. Currently, it is difficult to accurately perceive the creep behaviour of concrete at an early age in the test method of creep which is generally carried out. Therefore, it is necessary to evaluate the creep behaviour of concrete at early age and to establish a convenient test method to estimate the creep behaviour. Therefore, in this study, experiments were carried out for concrete at early age within one week. As the result of the experiments, it was shown that the creep strain is proportional to the load stress of concrete at an early age and the strain of specific creep decreases as the loaded age increases. In addition, based on the experimental results, an estimation equation for creep strain at early age was proposed. Within the scope of this experimental result, it was confirmed that the estimation equation proposed in this study accurately represented the creep behaviour of concrete at early age.

A Method for Estimating Creep Deformation of Structures Subjected to Cyclic Loading

1973 ◽  
Vol 40 (4) ◽  
pp. 928-934 ◽  
Author(s):  
J. J. Williams ◽  
F. A. Leckie
Keyword(s):  
Cyclic Loading ◽  
Creep Strain ◽  
Effective Stress ◽  
Creep Test ◽  
Creep Deformation ◽  
Cyclic Creep ◽  
Uniaxial Stress ◽  
Time Varying ◽  
Proportional Loading

A method is proposed for estimating structural creep deformation due to histories of cyclic proportional loading. The method applies to structures composed of materials whose creep strain due to constant uniaxial stress is given by an equation of the form ε(t)/ε0={σ/σ0}n{t/t0}m Knowledge of the form of the creep law for time-varying stress is not required, as use is made of an effective stress obtained from a single cyclic creep test.

Thermal Stress and Creep Strain Analyses of a 3D IC Integration SiP with Passive Interposer for Network System Application

2012 ◽  
Vol 2012 (1) ◽  
pp. 001038-001045 ◽  
Author(s):  
Sheng-Tsai Wu ◽  
John H. Lau ◽  
Heng-Chieh Chien ◽  
Yu-Lin Chao ◽  
Ra-Min Tain ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Creep Strain ◽  
High Power ◽  
Integrated Circuit ◽  
Printed Circuit Board ◽  
Solder Joints ◽  
Random Access ◽  
Circuit Board ◽  
3D Ic ◽  
Silicon Vias

In this study, the nonlinear thermal stress distributions at the Cu-low-k pads of Moore's law chips and creep strain energy density per cycle at the solder joints of a 3D IC integration system-in-package (SiP) are investigated. At the same time, the warpage of the TSV interposer and reliability assessment of solder joints in the architecture is examined. The analyzed structure comprises one PCB (printed circuit board), one BT (bismaleimide triazene) substrate, one interposer with through silicon vias (TSVs), two DRAM (dynamic random access memory) chips and one high power ASIC (application specific integrated circuit) chip. The high power chip and DRAM chips are supported, respectively on the top-side and bottom-side of the Cu-filled TSV interposer.

The Mechanism of The Die Crack in exposed Pad Quad Flat Package(ePad QFP) with Large Die due to Die-attach Adhesive with high modulus

2011 ◽  
Vol 2011 (1) ◽  
pp. 000711-000718
Author(s):  
Jin-Ho Kim ◽  
Dong-Nam Kim ◽  
Young-Chul Jo ◽  
Nam-Yong Kim ◽  
Seung-Geun Kang ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Stress Concentration ◽  
Coefficient Of Thermal Expansion ◽  
Plastic Packages ◽  
Die Attach ◽  
Quad Flat Package ◽  
Cte Mismatch ◽  
Major Property ◽  
Reliability Performance ◽  
Adhesive Materials

Thermal-enhanced plastic packages, such as exposed Pad Quad Flat Package (ePAD QFP), are more sensitive to thermal stress and warpage. As a result, thermal stress and warpage in ePAD QFP can lead to severe die cracking. This stress and warpage are mainly due to the thermal mismatch of packaging materials with different coefficient of thermal expansion (CTE). In particular, the die attach adhesive plays an important role in controlling stress and warpage in the package. In this paper, both experimental data and simulation were employed to gain a better understanding in a stress development and failure mechanism in ePAD QFP with a large die. Theoretical die-attach adhesives with different modulus were used for the evaluation of die crack and delamination by analysis of finite-numerical element method (FNEM). And the effect of the adhesion between Si die and Die-attach adhesive on the die crack was also discussed in this paper by FNEM. The simulation for thermal stress due to CTE mismatch was done by shadow moiré measurement technique and dynamic profiling method to verify the stress concentration area around the die in the package. And the delamination and die crack were simulated by thermal cycling test after changing appropriate adhesive materials that can directly affect on the die crack and the stress. The mechanism of die crack and the crack propagation through the die were mainly discussed in details at first and then the stress concentration and die crack initiation was verified by FNEM analysis and physical experimental validation. Finally, the major property of the die-attach adhesive to be considered for better reliability performance in ePAD QFP was suggested with die size.

High Temperature Rotors: Failure Mechanisms and Remnant Life Assessment

2006 ◽  
Author(s):  
Xiaoling Zhang
Keyword(s):  
High Temperature ◽  
Cyclic Loading ◽  
Crack Initiation ◽  
Crack Growth ◽  
Creep Strain ◽  
Operating Temperature ◽  
Failure Mechanisms ◽  
Creep Rupture ◽  
High Operating Temperature ◽  
Creep Crack

This paper presents the common failure mechanisms of high temperature rotors and the engineering approaches to their remnant life prediction. • Rotor bore fatigue crack growth — cracks from original forging defects or induced during long service life may grow under cyclic loading into its critical size causing fast fracture. • Shaft surface fatigue-creep interaction — high tensile residual stress relaxation under high operating temperature causes creep crack initiation. The cracks would then grow under the combination of cyclic loading and high operating temperature. • Remanent creep life at the centre of the rotor is based on the time while accumulated creep strain reaches its threshold level. • Creep rupture could occur at other locations such as the outside surface of the shaft at discs/shaft radii or blade fixings. Finite element method is a powerful tool to analyse stresses, temperature transients, creep strain and reference stress for creep rupture. Fracture mechanics analyses with R5 & R6 approaches were used to estimate the crack initiation and growth rates, the critical crack sizes and the type of the failure. Appropriate Paris law and Norton creep laws were used for fatigue and creep crack growth. Depending on the failure mechanism, a rotor’s remnant life is defined in terms of allowable starts and operating hours.

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