scholarly journals Bonding formation and gas absorption using Au/Pt/Ti layers for vacuum packaging

2022 ◽  
Vol 8 (1) ◽  
Author(s):  
Shingo Kariya ◽  
Takashi Matsumae ◽  
Yuichi Kurashima ◽  
Hideki Takagi ◽  
Masanori Hayase ◽  
...  
Keyword(s):  
Thermal Diffusion ◽  
Electronics Industry ◽  
Vacuum Packaging ◽  
Gas Absorption ◽  
Hermetic Sealing ◽  
Inner Surface ◽  
Gas Molecules ◽  
Residual Gas

AbstractIn this study, we developed a metal multilayer that can provide hermetic sealing after degassing the assemblies and absorbing the residual gases in the package. A package without a leak path was obtained by the direct bonding of the Au/Pt/Ti layers. After packaging, annealing at 450 °C caused thermal diffusion of the Ti underlayer atoms to the inner surface, which led to absorption of the residual gas molecules. These results indicated that a wafer coated with a Au/Pt/Ti layer can provide hermetic sealing and absorb residual gases, which can simplify vacuum packaging processes in the electronics industry.

Recent Progress In High-Resolution Shadowing For Biological Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 510-511 ◽  
Author(s):  
Heinz Gross ◽  
Katarina Krusche ◽  
Peter Tittmann
Keyword(s):  
Heavy Metal ◽  
High Resolution ◽  
Freeze Drying ◽  
Atmospheric Conditions ◽  
Vacuum Equipment ◽  
Transmission Electron ◽  
Gas Atmosphere ◽  
Gas Molecules ◽  
Residual Gas ◽  
Backing Layer

Freeze-drying followed by heavy metal shadowing is a long established and straight forward approach to routinely study the structure of dehydrated macromolecules. Very thin specimens such as isolated membranes or single macromolecules are directly adsorbed on C-coated grids. After rapid freezing the grids are transferred into a suitable vacuum equipment for freeze-drying and heavy metal shadowing.To improve the resolution power of shadowing films we introduced shadowing at very low specimen temperature (−250°C). To routinely do that without the danger of contamination we developed in collaboration with Balzers an UHV (p≤10-9 mbar) machine (BAF500K, Fig.2). It should be mentioned here that at −250°C the specimen surface acts as effective cryopump for practically all impinging residual gas molecules from the residual gas atmosphere.Common high resolution shadowing films (Pt/C, Ta/W) have to be protected from alterations due to air contact by a relatively thick C-backing layer, when transferred via atmospheric conditions into the TEM. Such an additional C-coat contributes disturbingly to the contrast at high resolution.

High and Moderate-Level Vacuum Packaging of Vibratory MEMS

2013 ◽  
Vol 2013 (1) ◽  
pp. 000705-000710 ◽  
Author(s):  
Igor P. Prikhodko ◽  
Brenton R. Simon ◽  
Gunjana Sharma ◽  
Sergei A. Zotov ◽  
Alexander A. Trusov ◽  
...  
Keyword(s):  
Vacuum Packaging ◽  
Moderate Level ◽  
Silicon On Insulator ◽  
Quality Factors ◽  
High Q ◽  
Hermetic Sealing ◽  
Hemispherical Resonator ◽  
Q Factors ◽  
Grade Performance

We report vacuum packaging procedures for low-stress die attachment and versatile hermetic sealing of resonant MEMS. The developed in-house infrastructure allows for both high and moderate-level vacuum packaging addressing the requirements of various applications. Prototypes of 100 μm silicon-on-insulator Quadruple Mass Gyroscopes (QMGs) were packaged using the developed process with and without getters. Characterization of stand-alone packaged devices with no getters resulted in stable quality factors (Q-factors) of 1000 (corresponding to 0.5 Torr vacuum level), while devices sealed with activated getters demonstrated Q-factors of 1.2 million (below 0.1 mTorr level inside the package). Due to the high Q-factors achieved in this work, we project that the QMG used in this work can potentially reach the navigation-grade performance, potentially bridging the gap between the inertial silicon MEMS and the state-of-the-art fused quartz hemispherical resonator gyroscopes.

Development of a Field Emission VP-SEM and Some Initial Applications

2001 ◽  
Vol 7 (S2) ◽  
pp. 882-883
Author(s):  
Masako Nishimura ◽  
Sukehiro Itoh ◽  
Steve Joens
Keyword(s):  
Field Emission ◽  
Chamber Pressure ◽  
Variable Pressure ◽  
Natural State ◽  
Backscattered Electrons ◽  
Pumping System ◽  
Multi Stage ◽  
Gas Molecules ◽  
Residual Gas ◽  
Differential Pumping

The use of variable pressure SEMs (VP-SEMs) is increasing in various fields of science and industry, allowing microscopy in a variable pressure environment of 1 ∼ 270 Pa utilizing backscattered electrons for imaging. The VP-SEM allows microscopy of insulated samples without the need for sample preparation. Charging artifacts can be minimized as well. When the VP-SEM is operated with a cooling stage, which allows cooling of samples at −20° and above, vaporization of water from samples is reduced. This permits microscopy of wet samples at close to the natural state for extended periods of time.Poor S/N ratio and deterioration of resolution, both of which are due to collisions among residual gas molecules and primary/backscattered electrons, have limited the performance of VP-SEMs. For resolving these limitations, we have completed the development of a new field emission VP-SEM which operates with a stable Schottky field emission source, a new environmental secondary electron detector (ESED), and a multi-stage differential pumping system. Fig. 1 shows a sectional view of the column with the differential pumping system. This design allows stable gun vacuum conditions with variable specimen chamber pressure 10 through 3,000 Pa, permitting a pressure difference from the gun by 1011 Pa without problems.

scholarly journals Some experiments on thermal diffusion

1921 ◽  
Vol 99 (700) ◽  
pp. 385-397 ◽  
Keyword(s):  
Steady State ◽  
Temperature Gradient ◽  
Thermal Diffusion ◽  
General Effect ◽  
Gas Molecule ◽  
Calculated Effect ◽  
Order Of Magnitude ◽  
Gas Molecules ◽  
The Difference ◽  
The Masses

It has been shown theoretically by Dr. S. Chapman that a temperature gradient applied to a uniform mixture of two gases will tend to produce non-uniformity of composition, the heavier and larger molecules diffusing towards the cooler side, and the smaller and lighter molecules diffusing towards the hotter side. This phenomenon was termed “thermal diffusion.” The difference in composition due to thermal diffusion increases until it is balanced by the opposite effects of ordinary diffusion, when a steady state will be reached. The effect will be greatest when the gases are mixed in nearly equal proportions by volume, and will be greater the more unequal are the masses and diameters of the gas molecules. It was also shown that the extent of the effect would vary with the character of the gas molecules, being at a maximum when the molecules behave like rigid elastic spheres. In the case where molecules behave like fifth power centres of force the effect would disappear entirely. Experiments made by Chapman and Dootson established the existence of the phenomenon. The results were chiefly qualitative, the nature and order of magnitude being in agreement with the theory. In no case were the differences equal to the theoretical values obtained on the assumption that gas molecules behave like rigid elastic spheres. Although the results are not claimed to be exact, the general effect could be regarded as rather less than a half of this calculated effect. The character of the gas molecule required to give this result would, however, be in agreement with that obtained for the actual gas molecules from the investigation of the variation of viscosity with temperature.

scholarly journals Efficacy of PPV Combined with Air Tamponade for Treatment of Inferior Retinal Breaks

2021 ◽  
Vol 2021 ◽  
pp. 1-5
Author(s):  
Yong Zhang ◽  
Xin Li ◽  
Guiping Pan ◽  
Zhen Tian ◽  
Siwei Liu ◽  
...  
Keyword(s):  
Anterior Segment ◽  
Gas Absorption ◽  
Retinal Breaks ◽  
Retinal Reattachment ◽  
Pars Plana ◽  
Air Tamponade ◽  
Residual Gas ◽  
The Difference ◽  
Gas Volume

Purpose. To observe the efficacy and safety of pars plana vitrectomy (PPV) combined with filtered air tamponade in the treatment of rhegmatogenous retinal detachment (RRD) with inferior retinal breaks. Methods. This retrospective study included 20 patients (20 eyes) with inferior retinal breaks in RRD; all underwent PPV combined with filtered air tamponade. Preoperative examinations included BCVA, IOP, anterior segment, fundus and locations, numbers, and sizes of retinal breaks and ocular B-mode ultrasonography. Postoperative examinations included BCVA, IOP, residual gas volume, retinal reattachment, and complications. Results. After follow-up for 1 year, the primary retinal reattachment rate was 95% and the final reattachment rate was 100%. Pre- and postoperative BCVA averaged 1.51 ± 0.63 and 0.97 ± 0.58 logMAR, respectively; the difference was statistically significant ( P < 0.001 ). Average pre- and postoperative IOP were not statistically different. The average volume of residual gas on the first day after the surgery was 77.5%; the gas was absorbed in all patients within 2 weeks; no significant postoperative complications were observed. Conclusion. PPV combined with filtered air tamponade is a safe and effective treatment for RRD with inferior retinal breaks. Notably, the retinal reattachment rate is high, gas absorption is rapid, and incidence of complications is low.

scholarly journals The thermal diffusion of radon gas mixtures

1942 ◽  
Vol 181 (984) ◽  
pp. 93-100 ◽  
Keyword(s):  
Force Field ◽  
Thermal Diffusion ◽  
Special Theory ◽  
Mean Value ◽  
Repulsive Force ◽  
Inert Gases ◽  
Inert Gas ◽  
Cold Side ◽  
The Mean ◽  
Gas Molecules

In continuation of earlier experiments (Harrison 1937) in which the thermal diffusion in radon-hydrogen and radon-helium mixtures was measured, the thermal diffusion of mixtures of radon-neon and radon-argon has now been studied. The mean value obtained for the ratio of the proportion by volume of radon on the cold side at 0° C to that on the hot side at 100° C, after thermal diffusion, was 1·074 for radon-neon mixtures, and 1·008 for radon-argon mixtures. In order to calculate the repulsive force field, F 12 , between these two pairs of molecules, the present results were combined with measurements of ordinary diffiisirm of radon into neon and radon into argon (Hirst & Harrison 1939), and viscosity determinations at various temperatures of neon and argon (Trautz & Binkele 1930). The special theory, due to Chapman (1929), of thermal diffusion of a rare constituent in a binary mixture was used to derive Flt. The values obtained for the repulsive force field between the dissimilar molecules at collision were: F 12 (radon-neon) = 1·9 x 10 -51 d -6·1 = ( d / d 0 ) -6·1 , d 0 = 4·8 x 10 -9 , F 12 (radon-argon) = 2·1 x 10 -43 d -5·1 = ( d 0 )-5·1 , d 0 = 4·3 x 10 -9 , d being the distance between the point centres of repulsive force and d 0 the value of d at which F 12 is 1 dyne. A comparison of the values obtained for the repulsive force index for radon-neon and radon-argon molecules with those obtained by Atkins, Bastick & Ibbs (1939) for binary mixtures of the first five inert gases shows that radon is the4 softest ’ of the inert gas molecules. Radon-argon molecules are the closest approach to the Maxwellian case yet studied experimentally.

Gas absorption by wavy falling liquid film formed on inner surface of vertical tubes

2003 ◽  
Vol 12 (1) ◽  
pp. 57-61 ◽  
Author(s):  
Akio Miyara ◽  
Tomoki Yamamoto ◽  
Toru Iemura ◽  
Takashi Shimada
Keyword(s):  
Liquid Film ◽  
Gas Absorption ◽  
Falling Liquid Film ◽  
Inner Surface ◽  
Vertical Tubes

The Simulation of Molecular Return Flux in Thermal Vacuum Test of Spacecraft

2015 ◽  
Vol 789-790 ◽  
pp. 471-476
Author(s):  
Zi Long Jiao ◽  
Li Xiang Jiang ◽  
Ji Peng Sun ◽  
Jian Guo Huang ◽  
Yun Fei Zhu
Keyword(s):  
Direct Simulation Monte Carlo ◽  
Solar Array ◽  
Direct Simulation ◽  
Thermal Vacuum ◽  
Spacecraft Design ◽  
Contamination Control ◽  
Gas Molecules ◽  
Simulation Monte Carlo ◽  
Residual Gas ◽  
Vacuum Test

In process of thermal vacuum test of spacecraft, the molecular contamination can have severe effects on performance and reliability of optical payload. In this article, we analyzed the contamination transport mechanism, simplified boundary conditions and input parameters based on physical understanding. We employed the Direct Simulation Monte-Carlo method to simulate the return flux of molecular contamination scattered by residual gas molecules in thermal vacuum tests of solar array and whole satellite. The results of simulation show that the return flux cannot be ignored, and its highest value would be 0.004. This would help the contamination control of spacecraft design, manufacture, test, and on-orbit operation.

A QUANTITATIVE STUDY OF SCATTERING PHENOMENA IN AN ELECTROMAGNETIC SEPARATOR

1964 ◽  
Vol 42 (1) ◽  
pp. 164-192 ◽  
Author(s):  
M. Menat
Keyword(s):  
Ion Beam ◽  
Mass Difference ◽  
Electromagnetic Mass ◽  
Gas Molecule ◽  
Gas Molecules ◽  
Residual Gas ◽  
Fractional Mass ◽  
Reciprocal Value ◽  
Reliable Interaction ◽  
Molecule Concentration

A series of recent experiments has shown that the elastic scattering of a directed ion beam by residual gas is one of the dominant factors causing contamination in an electromagnetic mass separator. This phenomenon is treated numerically, based on geometrical considerations and on an appropriate and reliable interaction potential between the ions and the residual gas molecules. The result is a relation[Formula: see text]expressing the fractional contamination as a function of: the residual gas molecule concentration nr, the fractional mass difference ΔM/M, the collector slit width Δx, the configuration factor [Formula: see text] and constants (σ0 and n) which appear in the expression for the differential cross section. The reciprocal value [Formula: see text] imposes an upper limit to the enhancement factor. By performing the various integrations in a different sequence, a general expression for the transmission from source to collector is obtained. The influence of losses caused by inelastic scattering can be easily incorporated. For elements with a mass number of about 200, scattered by air and for an accelerating voltage of about 30 kv, this expression takes the form:[Formula: see text]where L is the total ion path length in the separator.

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