• Applied Science and Convergence Technology
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• 제26권5호
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• pp.95-109
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• 2017

There are several contributions to the gas load of a system of which often the most important is outgassing. Adsorption occurs via two main processes, physisorption and chemisorption, and can be described using five (or six) classifying isotherms. Outgassing is the result of desorption of previously adsorbed molecules, bulk diffusion, permeation and vapourisation. Looking at the desorption rate, pumping speed and readsorption on surfaces, the net outgassing of the system can be calculated. There is significant variation in measured outgassing rates between different materials but also between published rates for the same materials, in part due to the number of different methods used to measure outgassing. This article aims to review the outgassing process, outgassing rates, measurement methods and techniques that can be used to reduce the outgassing of a system.

• 마이크로전자및패키징학회지
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• 제10권3호
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• pp.57-65
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• 2003

본 연구에서는 웨이퍼 레벨 진공 패키징된 MEMS자이로스코프 소자의 신뢰성 시험 및 분석을 통하여 웨이퍼 레벨 진공 패키징의 파괴 메카니즘을 연구하였다. 진공 패키징의 주된 파괴 모드는 누설, 가스투과, 그리고 outgassing이다. 누설은 접합 계면이나 재질의 결함을 통하여 주로 발생되며, 접합폭을 증가시키거나 단결정 실리콘을 사용하면 누설이 감소한다. Outgassing은 실리콘 및 유리기판의 표면 및 내부에서 발생하며 주로 $H_2O$와, $CO_2$, $C_3H_5$ 및 유기 오염물질이었다. Epi-poly의 경우 SOI 웨이퍼보다 약 10배의 outgassing을 발생시킨다. 또한 유리기판을 샌드블라스트 공정을 사용하여 가공한 경우, 약 2.5배의 outgassing 양이 증가한다. Outgassing 제거를 위해서는 접합 전에 웨이퍼를 pre-baking하는 과정이 필수적이며, outgassing의 발생을 최대로 하기 위한 최적의 pre-baking조건은 실리콘과 유리 웨이퍼를 $400^{\circ}C$와 $500^{\circ}C$ 사이에서 pre-baking하는 것이다.

• Applied Science and Convergence Technology
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• 제24권4호
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• pp.84-89
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• 2015

The base pressure and outgassing rate of a mild steel chamber were measured and compared to those of a stainless steel chamber. A combined sputter-ion and non-evaporable getter pump with a nominal pumping speed of 490 l/s generated the base pressure of $2.7{\times}10^{-11}$ mbar in the mild steel chamber and $1.2{\times}10^{-10}$ mbar in the stainless steel chamber. The rate-of-rise measurements show that the mild steel has an extremely low outgassing rate of $2.6{\times}10^{-13}$ mbar $ls^{-1}cm^{-2}$, which is about one-order of magnitude smaller than the outgassing rate of the stainless steels. Vacuum annealing of the mild steel at $850^{\circ}C$ reduced the outgassing rate further to $8.8{\times}10^{-14}$ mbar $ls^{-1}cm^{-2}$, which was comparable to the outgassing rate of a heat treated stainless steel for extreme-high vacuum use.

• 한국초전도ㆍ저온공학회논문지
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• 제20권4호
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• pp.11-15
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• 2018

Torque tubes in High Temperature Superconducting (HTS) motor transfer torque from superconducting field winding rotor to the room temperature shaft. It should have minimum heat conduction property for minimizing the load on cryo-refrigerator. Generally, these torque tubes are made with stainless steel material because of high strength, very low outgassing and low thermal contraction properties at cryogenic temperatures and vacuum conditions. With recent developments in composite materials, these torque tubes could be made of composites such as Kevlar and S-Glass, which have the required properties like high strength and low thermal conductivity at cryogenic temperatures, but with a reduced weight. Development and testing of torque tubes made of these composites for HTS motor are taken up at Bharat Heavy Electricals Limited (BHEL), Hyderabad in collaboration with Central Institute of Plastics and Engineering Technology (CIPET), Chennai and Indian Institute of Technology (IIT), Kharagpur. As these materials are subjected to vacuum, it is important to measure their outgassing rates under vacuum conditions before manufacturing prototype torque tubes. The present study focusses on the outgassing characteristics of Kevlar and S-Glass, using an Outgassing Measurement System (OMS), developed at IIT Kharagpur. The OMS facility works under vacuum environment, in which the test samples are exposed to vacuum conditions over a sufficient period of time. The outgassing measurements for the composite samples were obtained using pressure-rise technique. These studies are useful to quantify the outgassing rate of composite materials under vacuum conditions and to suggest them for manufacturing composite torque tubes used in HTS motors.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.631-632
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• 2011

• 반도체디스플레이기술학회지
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• 제8권1호
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• pp.7-12
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• 2009

The outgassing effects of selected vacuum materials on the vacuum characteristics were simulated by the $VacSim^{Multi}$ simulation tool. This investigation examined the feasibility of reliably simulating the outgassing characteristics of common vacuum chamber materials (aluminum, copper, stainless steel, nickel plated steel, Viton A). The optimum design factors for these vacuum systems were suggested based on the simulation results. The baking-out effects of the modeled systems and materials on the performance of the vacuum system were also analyzed. The simulation predicted that the overall outgassing effect was more significant in the TMP system than in the DP system and that the utilization of a booster pump has a greater effect on the evacuation time than on the ultimate pressure.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2003년도 춘계학술발표회 초록집
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• pp.54-54
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• 2003

MgO layer는 POP 패빌 내 유전증을 이온의 스퍼터링으로부터 보호하여 주며, 또한 높은 이차 전자 밤출 계수의 특성을 가지고 있어 구동 및 유지 전압을 낮춰 주는 역할을 한다. 그러나. MgO layer는 $H_20,{\;}CO_2,{\;}N_2,{\;}0_2$ 그리고 $H_2$와 같은 불순물 들을 쉽게 를착하는 단점이 있어, PDP의 특성 및 수명 단축에 영향을 줄 수 있다. 따라서, 본 연구에서는 atmospheric pressure plasma cleaning 과 low pressure i inductively coupled plasma (ICP) cleaning 처리에 의하여, 보호층으로 사용이 되는 MgO layer의 outgassing 특성을 조사하고자 한다. plasma cleaning에 의한 MgO layer 표면의 roughness와 불순물의 변화를 알아보기 위 하여 atomic force microscopy(AFM)과 x-ray p photoelectron spectroscopy(XPS)를 이용하여 측정 하였다. 또한, outgassing의 특성을 분석하기 위하여 MgO layer를 $400^{\circ}C$ 까지 온도를 가하여 온도에 따른 outgassing의 특성을 quadrupole mass spectrometer(QMS)를 이용하여 알아보았다. atmospheric pressure plasma cleaning 에서는 $He/O_2/Ar/N_2$의 gas를 사용하였으며, low pressure ICP cleaning 에 서는 Ar의 gas를 사용하였다. atmospheric pressure plasma cleaning는 low pressure ICP C cleaning과 비교해 더 낮은 outgassing을 관잘 할 수 있었으나. MgO 표면의 roughness는 low pressure ICP cleaning 후 더 낮은 것을 알 수 있었다. 또한 $He/O_2/Ar/N_2$의 gas를 사용 한 atmospheric pressure plasma cleaning 과 $Ar/O_2$의 gas를 사용한 ICP cleaning에서 이 차전자방출계수(SEEC)가 약 1.5~2.5배 증가된 것을 알 수 있었다.

• 한국진공학회지
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• 제5권3호
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• pp.175-180
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• 1996

Double conductance method is proposed as an effectvie way to measure real outgassing rates of materials regardless of their adsorbing power. The real outgassing rate and the sticking coefficient of the CFC (carbon fiber composite) which is used widely as the material for armor plates infusion experiment devices were obtained by adopting this method. At $40^{\circ}C$ the real ougassing rate was $Pa, m^3/s.m^2$(in $N_2$ equivalent), which was higher than 5 times the measured one, and the sticking coefficient was about 0.018($H_2O\; and \;H_2$ were the main residual gases).

• International journal of advanced smart convergence
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• 제6권4호
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• pp.1-8
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• 2017

In this work, the effects of fairly influential factors on performance of vacuum system, such as constant pressure and outgassing effect were simulated to propose the optimum design factors. Outgassing effects of selected vacuum materials on the vacuum characteristics were simulated by the $VacSim^{Multi}$ simulation tool. This investigation examined the feasibility of reliably simulating the outgassing characteristics of common vacuum chamber materials (aluminum, copper, stainless steel, nickel plated steel, Viton A). The optimum design factors for vacuum systems were suggested based on the simulation results. And, the effects of throttle valve applications on vacuum characteristics were also simulated to obtain the optimum design model of variable conductance on high vacuum system. Simulated vacuum characteristics of the proposed modelling were agreed with the observed experimental behaviour of real systems. Pressure limit valve and normally on-off control valve were schematized as the modelling of throttle valve for the constant process-pressure. Simulation results were plotted as pump-down curve of chamber and variable conductance of throttle valve. Simulated behaviors showed the applications of throttle valve sustained the process-pressure constantly, stably, and reliably.

• 항공우주기술
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• 제2권2호
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• pp.45-49
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• 2003

한국항공우주연구원 위성시험동에 설치된 Bake-Out 챔버를 통하여 과학위성 1호 비행모델(STSAT-1FM)에 대한 Bake-Out 시험이 수행되었다. 본 시험은 시험 후에 장착될 FIMS라는 광학장비에 영향을 미칠 Outgassing Rate의 측정 및 고온에서의 Bake-Out을 통한 오염물질 제거에 목적을 둔 시험으로 총 10일여 동안 시험이 수행되었다. Honeycomb Panel 및 Harness에 대한 시험(Batch 1), 조립된 비행모델에 대한 Bake-Out(batch 2), 그리고 part별로 펼쳐진 상태로의 Bake-Out 시험(Batch 3), 총 세 번의 시험으로 이루어졌다. 각각의 시험에 대하여 TQCM(Thermoelectric Quartz Crystal Microbalance) 및 RGA(Residual Gas Analyzer)를 통하여 Outgassing 물질에 대한 정량적, 정성적 측정 및 분석이 이루어졌다.