압축공기를 이용한 극미약(4.98keV) 연X선조사식 정전기 제거장치의 성능향상에 관한 연구

Abstract

The Advanced Study for Soft X-ray(4.98 keV) with using Compressed Air

Seo, Min-Seok

Division of Safety Engineering, The Graduate School, Pukyong National University

Abstract

These days, we have many instability facts to make products in the FPD(Flat Panel Display) industry. Maintenance of temperature & humidity, density of micro particle, vibration, change of magnetic field, and so on. Especially, the study of static electricity maintenance and control of micro particle contaminant are the most important part to solve the problem in this industry because the attachment of micro particles by static electricity is a major reason of a defect and it also make a poor quality. Besides, some devices are broken by electrostatic discharge. So we are using several types of ionizer to solve these problems. Normally, in case of using corona discharge type ionizer, it is quite good at removing the static electricity but it makes lots of micro particles at the top of their needles when it would be used. In length of time, micro particles can move to the bottom by the gravity and down flow in the manufactures. On the other hand, soft X-ray type ionizer doesn't have that problem and it is the best performance among the ionizer devices but it generates a radiation when it would be used. The purpose of this thesis is making a new device which generation of radiation is lower than former type. That’s why this thesis was made about using 4.98 keV soft X-ray type ionizer with compressed air, and then compared this ionizer with former type ionizer.

The results are following below.

1) 10.5 keV soft X-ray is well done to the distance of 1,000 mm. It has just shown 5.13 sec(+ Decay Time) and 6.02 sec(- Decay Time) at the distance of 1,000mm. On the other hand, 4.98 keV soft X-ray is not good at their electrostatic elimination. It has shown 82.17 sec(+ Decay Time) and 98.77 sec(- Decay Time) at the same distance. So we used 4.98 keV soft X-ray with compressed air to obtain the ability of its neutralization. As a result of using compressed air, it has just shown 1.92 sec(+ Decay Time) and 2.78 sec(- Decay Time) at the same distance. 2) In case of equivalent dose, 10.5 keV soft X-ray has been measured as 42.000 mSv/year at the distance of 1,000mm but it makes related worker dangerous because according to the Atomic Law, the level has to limit less than 500 mSv/year. But 4.98 keV soft X-ray has been measured as 208 mSv/year at the same distance. It means that it is able to cover the dangerous atomic about human skin but in the event of eyes, 4.98 keV soft X-ray is also dangerous. 3) The Equivalent dose is not related with using air so when soft X-ray was used with compressed air, the Equivalent dose is same as using only soft X-ray. It is capable of using at the high speed manufacturer when 4.98 keV soft X-ray is used with compressed air. It is shown that electrostatic elimination is just depend on the compressed air in case of not range of radiation. So according to the compressed air’s direction, static electricity would be eliminated. 4) Although 10.5 keV soft X-ray ionizer is good at their ability of neutralization, it could not remove the dust which is already stated on the panel. But in case of using compressed air, the dust could be got away by compressed air. 5) As a result, 4.98 keV soft X-ray ionizer is quite convenient for keeping observed Atomic Law and it is well done when it is used with compressed air, and moreover it is able to install in the inconvenient manufactures which have difficulty in installing.

In the future, it will be made about the lower electron voltage soft X-ray concerned about reducing the dangerous radiation. If advanced soft X-ray which is lower photon energy than this study is used with compressed air, it will be the best electrostatic elimination device in the world.