Reliability of Low Glass Transition Temperature COTS PEM’s for Space Applications

2003 ◽  
Author(s):  
M. Sandor ◽  
S. Agarwal ◽  
D. Peters ◽  
M. S. Cooper
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flame Retardants ◽  
Measurement Techniques ◽  
Test Results ◽  
Space Applications ◽  
Molding Compound ◽  
Different Temperatures ◽  
Compound Materials

Microcircuit manufacturers of Plastic Encapsulated Microcircuits (PEM’s) have made changes in epoxy molding compound materials and chemistry, which lower Glass Transition Temperature (Tg). PEM users in harsh environments have concerns if either the part in its application, or in evaluation or assembly, is used close to, or above, the Tg. Various Tg measurement techniques are available and discussed. Test results from one technique is reviewed. The implications of the Tg results on usage of these parts in space applications will be presented. Burn-in/ reliability test results of samples with low Tg PEM’s will be presented. The reliability experiments include testing under different temperatures. The issue being addressed is whether outgassing of molding compounds occurs when the temperature of the molding compound exceeds the Tg. This is a caution noted by many vendors. As an example outgassing of flame retardants can degrade parametric performance and wire bond integrity. This would be the case when PEMS are being qualified for Space applications using burn-in or in storage environments. JPL’s past experience has shown that COTS PEMS parametrics can degrade significantly even when the burn-in temperature is well below the Tg. Two different microcircuits exhibiting low Tg were evaluated. Assessment of final electrical test measurements and yield are shown.

scholarly journals Cure Kinetics Modeling of a High Glass Transition Temperature Epoxy Molding Compound (EMC) Based on Inline Dielectric Analysis

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1734
Author(s):  
Erick Franieck ◽  
Martin Fleischmann ◽  
Ole Hölck ◽  
Larysa Kutuzova ◽  
Andreas Kandelbauer
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Kinetic Parameters ◽  
Measurement Techniques ◽  
Process Conditions ◽  
Dielectric Analysis ◽  
High Glass Transition Temperature ◽  
General Process ◽  
Molding Compound

We report on the cure characterization, based on inline monitoring of the dielectric parameters, of a commercially available epoxy phenol resin molding compound with a high glass transition temperature (>195 °C), which is suitable for the direct packaging of electronic components. The resin was cured under isothermal temperatures close to general process conditions (165–185 °C). The material conversion was determined by measuring the ion viscosity. The change of the ion viscosity as a function of time and temperature was used to characterize the cross-linking behavior, following two separate approaches (model based and isoconversional). The determined kinetic parameters are in good agreement with those reported in the literature for EMCs and lead to accurate cure predictions under process-near conditions. Furthermore, the kinetic models based on dielectric analysis (DEA) were compared with standard offline differential scanning calorimetry (DSC) models, which were based on dynamic measurements. Many of the determined kinetic parameters had similar values for the different approaches. Major deviations were found for the parameters linked to the end of the reaction where vitrification phenomena occur under process-related conditions. The glass transition temperature of the inline molded parts was determined via thermomechanical analysis (TMA) to confirm the vitrification effect. The similarities and differences between the resulting kinetics models of the two different measurement techniques are presented and it is shown how dielectric analysis can be of high relevance for the characterization of the curing reaction under conditions close to series production.

Effects of High-Temperature Storage on the Glass Transition Temperature of Epoxy Molding Compound

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Ruifeng Li ◽  
Daoguo Yang ◽  
Ping Zhang ◽  
Fanfan Niu ◽  
Miao Cai ◽  
...  
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Storage Conditions ◽  
Mechanical Analysis ◽  
Core Material ◽  
Epoxy Molding Compound ◽  
Molding Compound ◽  
Different Temperatures

Abstract This article describes research on changes of glass transition temperature of electron encapsulated polymer-epoxy molding compound (EMC) after thermal oxidation under high-temperature air storage conditions. The evolutions of glass transition temperature of two EMCs with different compositions (different filling contents) under different temperatures (175, 200, and 225 °C) and different aging times (100, 500, and 1500 h) were analyzed by dynamic mechanical analysis (DMA) technology. Research results demonstrated that two glass transition temperatures occurred during thermal aging. These two temperatures were the glass transition temperature of the unaged core material (Tg1) and the glass transition temperature of completely oxidized surface material (Tg2). Tg2 increased continuously with the increase of temperature and the prolonging of the aging time. The filling content could have significantly influenced the aging degree of materials.

scholarly journals Effects of laminating and co-firing conditions on the performance of anode-supported Ce0.8Sm0.201.9 film electrolyte

2011 ◽  
Vol 43 (3) ◽  
pp. 305-312 ◽  
Author(s):  
X. Li ◽  
J. Lu ◽  
H. Wang
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flexural Strength ◽  
Single Cell ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Maximum Power Density ◽  
Film Electrolyte ◽  
Different Temperatures

In order to evaluate the laminating and co-firing technique on the performance of anode-supported Ce0.8Sm0.2O1.9 (SDC) film electrolyte and its single cell, NiO-YSZ and NiOSDC anode-supported SDC film electrolytes were fabricated by laminating 24 sheets of anode plus one sheet of electrolyte and co-firing. La0.4Sr0.6Co0.2Fe0.8O3-? (LSCF)-SDC cathode was coated on the SDC electrolytes to form a single cell. The lamination was tried at different laminating temperatures and pressures and the co-firing was carried out at different temperatures. The results showed that the laminating temperature should above the glass transition temperature (Tg) of the binder. The laminating pressure of 70 MPa resulted in warp of the samples. The best co-firing temperature of the anode-supported SDC film electrolyte was 1400?C. The SDC film electrolyte formed well adherence to the anode. The NiO-YSZ anode had larger flexural strength than the NiO-SDC anode. The NiO-YSZ anode-supported SDC film electrolyte single cell had an open circuit voltage of 0.803 V and a maximum power density of 93.03 mW/cm2 with hydrogen as fuel at 800?C.

scholarly journals The Glass Transition Temperature and Temperature Dependence of Activation Energy of Viscous Flow of Ovalbumin

2016 ◽  
Vol 39 (1) ◽  
pp. 13-25
Author(s):  
Karol Monkos
Keyword(s):  
Activation Energy ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Viscous Flow ◽  
Solvent Interactions ◽  
Model Free ◽  
Free Volume Model ◽  
Wide Range ◽  
Different Temperatures

Abstract The paper presents the results of viscosity determinations on aqueous solutions of ovalbumin at a wide range of concentrations and at temperatures ranging from 5°C to 55°C. On the basis of these measurements and three models of viscosity for glass-forming liquids: Avramov’s model, free-volume model and power-law model, the activation energy of viscous flow for solutions and ovalbumin molecules, at different temperatures, was calculated. The obtained results show that activation energy monotonically decreases with increasing temperature both for solutions and ovalbumin molecules. The influence of the energy of translational heat motion, protein-protein and protein-solvent interactions, flexibility and hydrodynamic radius of ovalbumin on the rate of decrease in activation energy with temperature has been discussed. One of the parameters in the Avramov’s equation is the glass transition temperature Tg. It turns out that the Tg of ovalbumin solutions increases with increasing concentration. To obtain the glass transition temperature of the dry ovalbumin, a modified Gordon-Taylor equation is used. Thus determined the glass transition temperature for dry ovalbumin is equal to (231.8 ± 6.1) K.

scholarly journals Construction of a TTT-η Diagram of High-Refractive Polyurethane Based on Curing Kinetics

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3474
Author(s):  
Shidi Huang ◽  
Guiming Zhang ◽  
Weiping Du ◽  
Huifang Chen
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Gelation Time ◽  
Curing Kinetics ◽  
Processing Parameters ◽  
Curing Process ◽  
Scanning Calorimetry ◽  
Different Temperatures ◽  
Temperature Transformation

A time–temperature–transformation–viscosity (TTT-η) diagram can reflect changes in the physical states of a resin, which take on significance for the study of the curing process of polyurethane resin lenses. Coupling the differential scanning calorimetry (DSC) test, the curing kinetic parameters of 1,4-bis(isocyanatomethyl)cyclohexane (H6XDI)/2,3-bis((2-mercaptoethyl)thio)-1-propanethiol (BES) polyurethane system were obtained. By phenomenological modeling, the relationships between degree, temperature, and time were obtained. An isothermal DSC test was carried out at 423 K. Based on the DiBenedetto equation, the relationships between glass transition temperature, degree of cure, and time were obtained, and the glass transition temperature was thus correlated with temperature and time. The gelation time at different temperatures was measured by rotary rheometry, and the relationship between gelation time and gelation temperature was established. The time–temperature–transformation (TTT) diagram of H6XDI/BES system was constructed accordingly. Subsequently, a six-parameter double Arrhenius equation was used as the basis for the rheological study. The viscosity was examined during the curing process. The TTT-η diagram was obtained, which laid the theoretical foundation for the optimization and setting of processing parameters.

Polymer Degradation from the Thermal Analysis Point of View

2004 ◽  
Vol 851 ◽  
Author(s):  
Ramón Artiaga ◽  
Ricardo Cao ◽  
Salvador Naya ◽  
Ana García
Keyword(s):  
Thermal Analysis ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Elevated Temperatures ◽  
Chemical Degradation ◽  
Space Environment ◽  
Space Applications ◽  
Analysis Methods ◽  
The One

ABSTRACTThis work applies different thermal analysis methods to polymer based materials degradation, studying the degradation process itself and evaluating the degree of material damage as a consequence of chemical degradation by thermal or radiation effects. On the one hand, thermal degradation in varied atmospheres is investigated by means of thermogravimetric analysis (TGA) in dynamic experiments. The authors find that the evolution of the sample mass follows a mixture of logistics models, and these can fit an overall TGA curve. The fitting parameters have important physical meaning related to the kinetics of the different processes involved and to the relative amount of each component in the sample. The method itself entails separating overlapping processes. Other improvements made by the authors are related to reducing the noise and smoothing the TGA and differential scanning calorimetry (DSC) data, particularly when estimating TGA derivatives through logistic regression.Analyzing many materials by means of TGA results in more or less complex traces that do not allow a simple parametric fit like the one described above. Although it reproduces asymptoticity at the beginning and end of the reaction, there are times when many processes overlap, resulting in a complex trace that would need a high number of logistic components to be adequately fitted. However, it is possible to use a local polynomial regression model instead. This is also applicable to DSC traces, whose shapes are totally different from those found in TGA. The authors propose a model based on a nonparametric estimation, where the fit's suitability very much depends on the bandwidth selection, especially where derivatives are concerned. The proposed model gives a satisfactory fitting. It smoothes noise and always provides reliable values, different from those obtained by other methods strongly dependent on user choice.On the other hand, to evaluate the degree of damage by thermal analysis methods, dynamic mechanical analysis (DMA) is applied to polyamides. The glass transition temperature is measured before and after exposure to varying doses of proton radiation, emulating the space environment. Other examples show how exposure over long periods at moderately elevated temperatures results in reduction of some mechanical properties. Additionally, the effect of different nanofillers on styrene-isoprene-styrene block copolymers is evaluated by DMA. A shift in the glass transition temperature seems to be dependent on nanofiller content. The degradation of some materials suitable for space applications, such as polyethylene and polyamide, are also briefly reviewed.

Effects of Programming Temperature on the Efficiency of Self-Healing Polymers

2012 ◽  
Author(s):  
Yves Quentin Yougoubare ◽  
Ifeanyi Janarus Okoro ◽  
Su-Seng Pang
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Shape Recovery ◽  
Strength Properties ◽  
Self Healing ◽  
Test Results ◽  
Crack Healing ◽  
Micro Cracks ◽  
Intrinsic Correlation

Self-healing shape memory polymers possess the ability to heal macro and micro cracks by autonomic processes or when subjected to a suitable external stimulus. Recent advancements in the field have shown that the healing capabilities of self-healing polymers can be improved, thus yielding to high healing efficiencies. Depending on the application, the efficiency may refer to shape fixity, shape recovery ratio, dimensions recovery, strength regain, crack healing, etc. Based on test results, it is established that there is an intrinsic correlation between pre-strain levels, shape fixing and free shape recovery of samples programmed above the glass transition temperature (Tg). For samples programmed at multiple temperatures (above and below the glass transition temperature), the absence of lateral and 3D confinements lead to poor to no crack healing. Better compressive strength properties were, however, achieved by samples programmed at higher temperatures above Tg.

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