Film cassette for gaseous vapor deposition

A cassette for supporting a length of a film substrate during a gaseous vapor deposition process, the film substrate having a predetermined width dimension at the gaseous deposition temperature, the cassette comprising:

• a central shaft having an axis therethrough;
• a first and a second end plate, each end plate being mounted to the shaft, each end plate comprising a central hub from which radiate a plurality of angularly spaced spokes,
• the spokes of each end plate having an interior surface that lies on a reference plane, the reference plane being oriented substantially perpendicular to the axis of the shaft,
• the interior surfaces of spokes of the end plates being confrontationally disposed and spaced apart by a predetermined interspoke spacing,
• each end plate having a spiral rib mounted to the interior surface of the spokes thereof,
• each spiral rib having a predetermined number of uniformly spaced turns and a predetermined pitch associated therewith,
• the spaces between adjacent turns of the spiral rib defining a spiral groove on each end plate able to accept an edge of a film, each spiral groove having a first end and a second end,
• the spiral groove in one end plate facing toward the spiral groove in the other end plate with the first and second ends of each respective groove being axially aligned,
• each rib having a cross sectional configuration in a radial plane containing the axis of the shaft, the cross sectional configuration exhibiting substantially linear major edges,
• each rib having a predetermined width dimension measured from the interior surface of the spoke on which the rib is mounted in a direction parallel to the axis of the shaft, a predetermined average thickness dimension measured in a radial direction with respect to the axis of the shaft, and a width-to-average-thickness aspect ratio of at least 2:1, wherein
• the interspoke spacing is at least three hundred millimeters (300 mm) and is greater than the width dimension exhibited by a film substrate at a gaseous deposition temperature, and
• the width dimension of the rib on each end plate is between about 0.5% to about 2.0% of the interspoke spacing.