The Characteristics of the Sealed Parts in Super High Pressure Mercury Discharge Lamps

Abstract

Super high pressure mercury discharge lamps have been used under conditions of more than 1MPa of internal pressure. They are usually used in exposure processes, such as PCBs patterning, as well as in LCDs and semiconductors. In addition, they must be secured for rupture, because of extreme internal pressure, thermal loads and so on, required by their use. Furthermore, ruptures may occur from the sealed parts in the lamps. Thus, it is necessary to examine the mechanical characteristics of the sealed parts. The objectives of this paper are to examine the sealed parts of the lamps to withstand under internal pressure experimental conditions and to calculate the stress distribution to predict the rupture potential using finite element calculations. We also conducted rupture tests of the lamps under static water pressure conditions. The lamps’ stress distributions were observed in the rupture tests by using photoelasticity. As a result, we found the relationship between the shape of sealed parts and their rupture pressure. Ruptures were occurd where the boundaries of the sealed parts were joined by the silica glass and molybdenum foil were joined. We found that the rupture direction agreed with those obtained by FEM. Finally, it is impotant to note the relationship between the shapes of the sealed parts and their resistance to rupture while under internal pressure is important factor in developing an optimum design for the lamps.