Packaging Induced Die Stresses—Effect of Chip Anisotropy and Time-Dependent Behavior of a Molding Compound

2003 ◽  
Vol 125 (4) ◽  
pp. 520-526 ◽  
Author(s):  
W. D. van Driel ◽  
J. H. J. Janssen ◽  
G. Q. Zhang ◽  
D. G. Yang ◽  
L. J. Ernst
Keyword(s):  
Creep Compliance ◽  
Viscoelastic Behavior ◽  
Master Curves ◽  
Temperature Dependent ◽  
Molding Compound ◽  
Dependent Behavior ◽  
Quad Flat Package ◽  
Different Temperatures ◽  
Induced Stresses

This paper investigates the effect of the anisotropic behavior of the die and the time- and temperature-dependent behavior of epoxy molding compound on the packaging induced stresses for a quad flat package. Finite element (FE) simulations using isotropic and anisotropic properties of the die are carried out, respectively, and the results are compared. Creep experiments were performed at different temperatures ranging from −65°C to 230°C to obtain the long-term master curves and the related shift factors for the creep compliance of the molding compound. FE models which incorporate the viscoelastic constitutive relation of the material are constructed to simulate the thermo-mechanical stresses caused by the packaging processes. The influences of both the chip anisotropy and the viscoelastic behavior of the molding compound on the packaging induced stresses are discussed.

Polymers for Solar Domestic Hot Water: Long-Term Performance of PB and Nylon 6,6 Tubing in Hot Water

2004 ◽  
Vol 126 (1) ◽  
pp. 581-586 ◽  
Author(s):  
Chunhui Wu ◽  
Susan C. Mantell ◽  
Jane Davidson
Keyword(s):  
Creep Compliance ◽  
Hot Water ◽  
Master Curves ◽  
Burst Strength ◽  
Domestic Hot Water ◽  
Nylon 6,6 ◽  
Creep Modulus ◽  
Long Term Performance ◽  
Term Performance

Polymers offer a lightweight, low cost option for solar hot water system components. Key to the success of polymer heat exchanger components will be the long term mechanical performance of the polymer. This is particularly true for heat exchangers in which one of the fluids is pressurized hot water. For domestic hot water systems, polymer components must not fail after many years at a constant pressure (stress levels selected to correspond to 0.55 MPa in a tube) when immersed in 82°C potable water. In this paper, the long term performance of two potential heat exchanger materials, polybutylene and nylon 6,6, is presented. Two failure mechanisms are considered: failure caused by material rupture (as indicated by the hydrostatic burst strength) and failure caused by excessive deformation (as indicated by the creep modulus). Hydrostatic burst strength and creep modulus data are presented for each material. Master curves for the creep compliance as a function of time are derived from experimental data. These master curves provide a mechanism for predicting creep modulus as a function of time. A case study is presented in which tubing geometry is selected given the hydrostatic burst strength and creep compliance data. This approach can be used to evaluate properties of candidate polymers and to design polymer components for solar hot water applications.

scholarly journals Effects of High-Temperature Storage on the Elasticity Modulus of an Epoxy Molding Compound

Materials ◽  
2019 ◽  
Vol 12 (4) ◽  
pp. 684
Author(s):  
Ruifeng Li ◽  
Daoguo Yang ◽  
Ping Zhang ◽  
Fanfan Niu ◽  
Miao Cai ◽  
...  
Keyword(s):  
High Temperature ◽  
Elasticity Modulus ◽  
Glassy State ◽  
Storage Conditions ◽  
Material Structure ◽  
Epoxy Molding Compound ◽  
Molding Compound ◽  
Different Temperatures ◽  
Temperature Storage

Changes in the elasticity modulus of an epoxy molding compound (EMC), an electronic packaging polymer, under high-temperature air storage conditions, are discussed in this study. The elasticity modulus of EMC had two different compositions (different filling contents) under different temperatures (175, 200, and 225 °C) and aging times (100, 500, and 1500 h), which were analyzed by using dynamic mechanic analysis technology. The results revealed that the elasticity modulus increased in the thermal aging process, with an increase in the temperature and the aging time. The increments of the glassy and rubbery states were similar. However, the growing rate was significantly different, and the growth of the rubbery state was significantly higher than that of the glassy state. The filling content influenced the degree of aging of the materials significantly. At a low filling content, long-term aging under high temperatures completely changed the material structure, and the mechanical properties of the polymer were reduced.

Viscoelastic Characterization of an Epoxy-Based Molding Compound

1995 ◽  
Vol 390 ◽  
Author(s):  
V. H. Kenner ◽  
M. R. Julian ◽  
C. H. Popelar ◽  
M. K. Chengalva
Keyword(s):  
Stress Relaxation ◽  
Strain Rate ◽  
Constant Strain Rate ◽  
Viscoelastic Behavior ◽  
Tensile Tests ◽  
Prony Series ◽  
Master Curves ◽  
Molding Compound ◽  
Relaxation Curves

ABSTRACTThis paper describes the viscoelastic characterization of a highly filled epoxy molding compound commonly used in electronic packaging applications. Both stress relaxation tests and constant strain rate tensile tests were conducted. The material was found to be nonlinear in its viscoelastic behavior and to be amenable to horizontal shifting to form master curves. A representation of the master stress relaxation curves in terms of a Prony series is given, and the use of this representation illustrated in the context of both linear and nonlinear representations of the viscoelastic behavior to predict the results of the constant strain rate experiments.

Morphology and Long Term Behavior of Polymer Cement Concrete

1989 ◽  
Vol 179 ◽  
Author(s):  
K. P. Grosskurth
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polymeric Materials ◽  
Heterogeneous Material ◽  
Cement Concrete ◽  
Temperature Dependent ◽  
Dependent Behavior ◽  
Long Term Behavior

AbstractPolymer-modified cement concrete represents a heterogeneous material whose properties are influenced more by the properties of the polymers than by the properties of the cement component. Typical of polymeric materials are their temperature dependent behavior. This temperature dependence can be related to the glass transition temperature of the polymer. In cases where the temperature is higher than the glass transition temperature, strength decreases while deformability simultaneously increases. Polymeric films are formed in the dispersed polymer systems as a result of reactions occurring at the glass transition temperature. A styrene/acrylic modified concrete was studied at different polymer loadings. The tensile and compressive strengths of this system were studied as a function of temperature. Increasing deformability temperatures principally at higher polymer loadings near the glass transition temperature and decreasing strength occurred.

The Creep Behavior of Wood-Polymer Composites

2013 ◽  
Vol 815 ◽  
pp. 632-638
Author(s):  
Yuan Zhu ◽  
Pei Ying Liu ◽  
Zhi Hong Jiang
Keyword(s):  
Power Law ◽  
Creep Behavior ◽  
Creep Compliance ◽  
Burgers Model ◽  
Wood Polymer ◽  
Different Temperatures ◽  
Linear Viscoelastic ◽  
Term Creep ◽  
Long Term Behavior

The creep behavior of WPCs needs to be addressed when developing and using this kind of materials. In this paper, the creep behavior of WPCs under linear viscoelastic region was investigated at different temperatures and bamboo flours levels. The creep compliance increase with the rise of temperature, the addition of bamboo flour has a positive effect on the creep behavior. Burgers model, Findley power law and TTSP were used to predict the long-term behavior of this kind material. Finely power law can well describe the creep properties of WPCs while Burgers model begins to diverge from measured data at about 100min. The application of TTSP was used to create master curve covered more than 108 from 30-min short-term creep compliance curves.

Characterization of Linear Viscoelasticity Evolution of Epoxy Molding Compound Subjected to High Temperature Long Term Aging

2021 ◽  
Author(s):  
Pradeep Lall ◽  
Yunli Zhang ◽  
Haotian Wu ◽  
Jeff Suhling ◽  
Edward Davis ◽  
...  
Keyword(s):  
High Temperature ◽  
Power Systems ◽  
Linear Viscoelasticity ◽  
Aging Effect ◽  
Epoxy Molding Compound ◽  
Molding Compound ◽  
Long Period ◽  
Different Temperatures ◽  
Safety Systems

Abstract Much of the electronics used to support power systems and enable safety systems resides underhood where operating temperatures are much higher than in traditional consumer applications. Underhood electronics may be subjected to sustained high temperature environment 150°C for long period of time during operation. However, there is insufficient information about the viscoelasticity of epoxy molding compound stored in sustained high temperature for long period of time. In this paper, two different types of epoxy molding compounds have been prepared and aged under two different temperatures: 100°C and 150°C. Multi-frequency scan dynamic mechanical analyzer (DMA) test has been conducted to study the viscoelasticity evolution from pristine, 40 days, 80 days, 120 days. The master curve has been obtained and the prony parameters of EMCs have been calculated. The aging effect of linear viscoelasticity has been discussed.

scholarly journals Assessment of the stepped isothermal method for accelerated creep testing of high-density polyethylene

2021 ◽  
Author(s):  
Gerald Pilz ◽  
Stefan Wurzer ◽  
Matthias Morak ◽  
Gerald Pinter
Keyword(s):  
Creep Behavior ◽  
High Density Polyethylene ◽  
Creep Compliance ◽  
High Density ◽  
Creep Testing ◽  
Time Range ◽  
Master Curves ◽  
Isothermal Method ◽  
Temperature Levels

AbstractThermoplastic materials are increasingly used in demanding structural applications under, in some cases, long-term static loading over several decades. In this regard, the stepped isothermal method (SIM) with creep testing at stepwise increased temperature levels in combination with time-temperature superposition (TTSP) provides a very time efficient procedure for long-term creep characterization. In the present study, the creep behavior of an injection molded high-density polyethylene material (HDPE) was investigated by SIM in the thermally untreated state as well as after annealing.Due to experimental issues regarding the heating behavior of the specimens and non-linear viscoelastic behavior, particularly at elevated temperatures, bi-directional curve shifting was required in order to generate meaningful master curves for creep compliance. In a first step, an Arrhenius equation was used for the horizontal curve shifting, based on activation energies, determined in additional multi-frequency dynamic mechanical analysis (DMA). Continuous master curves were then obtained by empirical vertical shifting of the individual creep curve segments for the different temperature levels. In general, good agreement was observed between the resulting SIM master curves and the corresponding conventionally measured creep compliance curves at least for a time range up to 300 hours. Furthermore, significant differences in the creep tendency of the annealed material state compared to the thermally untreated condition revealed the distinct influence of the thermal history on the resulting creep behavior.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Heat wave effects on biomass and vegetative growth of macrophytes after long-term adaptation to different temperatures: a mesocosm study

2015 ◽  
Vol 66 (3) ◽  
pp. 265-274 ◽  
Author(s):  
Y Cao ◽  
ÉM Neif ◽  
W Li ◽  
J Coppens ◽  
N Filiz ◽  
...  
Keyword(s):  
Heat Wave ◽  
Vegetative Growth ◽  
Wave Effects ◽  
Different Temperatures
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