flange 79 may be formed at the edge of the support plate 75 for providing a screw connection with the side support 73 by screw bolts 80 or the like fastening means for example referring to fig6 there is shown a preferred support plate 75 of the present invention the support plate 75 has a plurality of through holes 81 to facilitate draining during a rinse operation also the dynamic performance of the cassette 7 may be adjusted by the locations and number of the through holes 81 on the support plates 75 it is well known in the vibration theory that the natural resonance frequency of the support plate 75 as well as that of the cassette 7 may be shifted by the arrangement of the through holes 81 upon an appropriate arrangement of the through holes 81 on the support plates 75 the glass substrate 4 sustained on the support plate 75 may be away from possible resonance damage resulted from operations of the neighboring equipments in one embodiment of the present invention the support plate 75 may be designed as a thin plate structure so as to reduce the weight but to increase the supporting capacity of the cassette 7 in the application of thin shells or plates the thin corrugated plate structure has.