Polyimide Copolymers Containing Various Levels Of The 6F Moiety For High Temperature And Microelectronic Applications

1991 ◽  
Vol 227 ◽  
Author(s):  
M. Haider ◽  
E. Chenevey ◽  
R. H. Vora ◽  
W. Cooper ◽  
M. Glick ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Electrical Properties ◽  
Oxidative Stability ◽  
Trifluoromethyl Group ◽  
Thermal And Mechanical Properties

ABSTRACTTrifluoromethyl group-containing polyimides not only show extraordinary electrical properties, but they also exhibit excellent long-term thermo-oxidative stability. Among the most thermomechanically stable structural polyimides are those from 6F dianhydride (6FDA) and 6F diamines. The effects of substituting non-fluorine containing monomers such as BTDA, mPDA and 4,4′-DADPS for the hexafluoroisopropylidene monomers on the dielectric, thermo-oxidative, thermal and mechanical properties of the copolymers were studied.

Research on Barite Concrete Mixed with Fly Ash

2013 ◽  
Vol 275-277 ◽  
pp. 2107-2111
Author(s):  
Qiu Lin Zou ◽  
Jun Li ◽  
Zhen Yu Lai
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Compressive Strength ◽  
High Temperature ◽  
Fly Ash ◽  
Apparent Density ◽  
Cycle Times ◽  
Residual Compressive Strength ◽  
Temperature Performance

Barite concrete with density grade of 3 and strength grade of C30 was prepared by mixing with different fineness of fly ash. The workability, mechanical properties and long-term high temperature performance of the prepared barite concrete were researched. Results show that the workability of barite concrete is improved by mixing with fly ash, and no segregation of mixture has been observed. The apparent density and 3d, 28d compressive strength of barite concrete are decreased obviously after mixing with fly ash. But with the increasing of the fineness of fly ash, the apparent density and 3d, 28d compressive strength of barite concrete have a slight increase. High temperature residual compressive strength is decreased with the increasing of temperature. The cycle times of heat treatment at 400°C only has a little effect on residual compressive strength of barite concrete.

Mitigation of High Temperature Environments on Electrical Disconnects

2018 ◽  
Vol 2018 (HiTEC) ◽  
pp. 000148-000153
Author(s):  
Kenneth P. Dowhower
Keyword(s):  
High Temperature ◽  
Electrical Properties ◽  
Stress Relaxation ◽  
Surface Treatment ◽  
Material Properties ◽  
Mechanical Stability ◽  
Contact Interface ◽  
Insulating Materials ◽  
Temperature Applications

Abstract The electrical interconnect is an essential component of most electrical system configurations. The ability of the interconnect interface to reliably transmit power and / or data throughout the system is critical to its overall performance. Degradation of the mechanical or electrical properties of the interface can reduce the system performance or in severe cases, make it inoperable. There are several factors which can inhibit the performance of the interconnect, one of most severe is long term exposure to elevated temperatures. This effect can also be accelerated when combined with other severe environmental conditions such as high vibration and physical shock, which are often found in down hole oil and gas well drilling applications. This type of exposure can significantly degrade the essential properties of a reliable electrical interface such as contact resistance, mechanical stability, and electrical isolation. This paper will present options for design features and material properties that can be incorporated into an interconnect design that will mitigate these adverse effects. Specifically, this paper addresses the material properties of the contact interface and its surface treatment, the mechanical and electrical properties of the insulating material, the robustness of the mating features and the contact retention system. Two key features of the contact interface that are discussed are the stability of its electrical resistance and the robustness of its mechanical retention. Long term exposure to high temperatures typically induces stress relaxation in the compliant members of the contact interface that are required to produce a stable, low resistance interface, while allowing for a high level of mate / unmate durability. Stress relaxation can also reduce the mechanical stability of the contact interface where metal or plastic retention features are utilized. In the case of retention through epoxy bonding, imparting thermal stress at the bonding surface can result in loss of adhesion and / or retention. The surface treatment of the contact interface has also been shown to be a contributing factor in its electrical stability in high temperature applications. Typically, the interface is plated with a hard gold over nickel finish, which provides a noble interface that is corrosion resistant, but with the hardness required to withstand many mate / unmate cycles. A small percentage of nickel or cobalt are typically alloyed with the gold to produce the required hardness. In most applications, it has minimal impact on the overall resistance of the contact interface. In high temperature applications, however, it can tend to diffuse through the gold to the contact interface. Since these materials have a higher resistivity, they can negatively affect the resistance of the interface. The impact of this effect is reviewed in this paper. Finally, results of the evaluations on high temperature insulating materials and bonding epoxies are presented in this paper. The mechanical and dielectric stability of the insulating materials and the adhesion properties of the epoxy used for contact retention were the primary concerns for their evaluation. The verification tests that included at temperature exposure were conducted at +260°C to simulate extreme use cases for most down hole applications.

Solid State Bonding of CuCrZr to Duplex Stainless Steel

2013 ◽  
Vol 302 ◽  
pp. 136-139 ◽  
Author(s):  
Ho Sung Lee ◽  
Jong Hoon Yoon ◽  
Joon Tae Yoo ◽  
Ji Ung Choi
Keyword(s):  
Mechanical Properties ◽  
Stainless Steel ◽  
High Temperature ◽  
Solid State ◽  
Duplex Stainless Steel ◽  
High Strength ◽  
Atomic Diffusion ◽  
Thermal And Mechanical Properties ◽  
Solid State Bonding ◽  
Duplex Steel

In the solid state bonding, joint are made by pressing surfaces together at high temperature so that a bond grows across the interface by atomic diffusion. In order to satisfy both requirements of thermal and mechanical properties of aerospace vehicle, conductive CuCrZr alloy was bonded to duplex steel with high strength. Solid state bonding was performed at 3 different pressure conditions and at temperatures of 850°C and 950°C. Microstructural and mechanical evaluation was performed to obtain the optimum joining condition.

Flip-Chip Ball Grid Array Lead-Free Solder Joint Under Reliability Test

2005 ◽  
Vol 127 (4) ◽  
pp. 446-451 ◽  
Author(s):  
Ming-Hwa R. Jen ◽  
Lee-Cheng Liu ◽  
Jenq-Dah Wu
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Service Time ◽  
Flip Chip ◽  
Failure Modes ◽  
Mechanical Responses ◽  
Operational Life ◽  
Different Temperatures ◽  
Free Solder

The work is aimed to investigate the mechanical responses of bare dies of the combination of pure tin∕Al–NiV–Cu Under bump metallization (UBM) and packages of pure tin∕Al–NiV–Cu UBM/substrate of standard thickness of aurum. The mechanical properties under multiple reflow and long term high temperature storage test (HTST) tests at different temperatures and the operational life were obtained. A scanning electron microscope was used to observe the growth of IMC and the failure modes in order to realize their reaction and connection. From the empirical results of bare dies, the delamination between IMC and die was observed due to the tests at 260 °C multiple reflow. However, their mechanical properties were not affected. Nevertheless, the bump shear strength of bare dies were decreased by HTST tests. In package, all the results of mechanical properties by multiple reflow test and HTST test were significantly lowered. It was shown that the adhesion between bump and die reduced obviously as tests going on. As for high temperature operational life test in the conditions of 150 °C and 320 mA (5040A∕cm2), the average stable service time of the package was 892 h, and the average ultimate service time of the package was 1053 h.

Effect of Long-Term Ageing at 600 °C on Microstructure of ZG1Cr10MoWVNbN Martensitic Heat-Resistant Steel

2018 ◽  
Vol 37 (6) ◽  
pp. 539-544
Author(s):  
Chengzhi Zhao ◽  
Ning Li ◽  
Yihan Zhao ◽  
Hexin Zhang
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
M23c6 Carbide ◽  
Resistant Steel ◽  
Steam Turbines ◽  
Heat Resistant Steel ◽  
Property Variation ◽  
Heat Resistant ◽  
Before And After

AbstractA new kind of martensitic ZG1Cr10MoWVNbN heat-resistant steel has been attracted more attentions in recent years, which is mainly applied in ultra-supercritical steam turbines. The ageing property for ZG1Cr10MoWVNbN heat-resistant steel is very important because it often serves for long-time at high-temperature environment. Herein, a long-term ageing heat treatment was conducted on ZG1Cr10MoWVNbN steel at 600 °C heat for 17,000 hours. The microstructure evolution and property variation of the ZG1Cr10MoWVNbN steel were analysed before and after ageing, and also the effect of the precipitates on the mechanical properties was studied. The result showed that strength, the plastic index and impact power of the ZG1Cr10MoWVNbN steel were gradually decreased after long-term and high-temperature ageing at 600 °C due to the changes of martensite morphology and the coarsening of M23C6 carbide precipitation phase. Furthermore, fine precipitation of matrix MX carbide can also attribute to the change of mechanical properties at high temperature.

High-performance PEN/GF crosslinkable thermoplastic composites: preparation, properties, and crosslinking reaction

2011 ◽  
Vol 45 (24) ◽  
pp. 2587-2592 ◽  
Author(s):  
Jian Yang ◽  
Jiachun Zhong ◽  
Rui Zhao ◽  
Xiaobo Liu
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
High Temperature ◽  
High Performance ◽  
Thermoplastic Composites ◽  
Crosslinking Reaction ◽  
Thermal And Mechanical Properties ◽  
Continuous Glass Fiber ◽  
Glass Fiber Reinforced ◽  
Properties Of Composites

The continuous glass fiber-reinforced polyarylene ether nitriles (PEN) composites were successfully fabricated from PEN pre-impregnated glass fabric mates and PEN films using a film-stacking method. The work involved heat treatment for crosslinking reaction of PEN, and so it provided an interesting comparison of how heat treatment can influence the properties of composites. Detailed study on heat treatments for crosslinking reaction of PEN in the catalysis of the ZnCl2 at high temperature promoting the thermal and mechanical properties of composites were also investigated. The results showed that the thermal and mechanical properties of composites were enhanced by heat treatment, which is due to the fact that PEN resins could be crosslinked by the catalytic action of ZnCl2 at high temperature and formed triazine rings with a more thermally stable structure.

Nafion – Azole Composite Membranes for High Temperature PEMFC

2014 ◽  
Vol 783-786 ◽  
pp. 1692-1697
Author(s):  
Je Deok Kim ◽  
Mun Suk Jun
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
High Temperature ◽  
Proton Conductivity ◽  
Composite Membrane ◽  
Room Temperature ◽  
Composite Membranes ◽  
Thermal And Mechanical Properties ◽  
High Proton Conductivity ◽  
High Proton

Nafion-azole (benzimidazole, 1,2,4-triazole, 1,2,3-triazole) composite membranes were prepared by room temperature and autoclave solution processing for high temperature (above 100 °C) PEMFC. Among the various Nafion – azole composite membranes, Nafion – 1,2,3-triazole membrane showed excellent flexibility, thermal stability, and homogeneous structure. Nafion – 1,2,4-triazole composite membrane had high thermal and mechanical properties, and also showed high proton conductivity of 0.02 S/cm at the temperature of 160 °C under dry (N2) condition.

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