FAS is clearly the technology leader and inventor of this technology. So far, the competition has only had limited effect on FAS sales. Other attempted competition has had the benefit of verifying that the technology developed and patented by FAS is in-fact the emerging world standard, with no known viable next generation competition, particularly for large substrate applications.
 

SPIN COAT: 
In this process, a pool of process fluid is dispensed into the center of the substrate. The substrate is then rotated on a central axis to distribute the fluid across the substrate; when the fluid reaches the edge of the substrate, it is thrown off and is later discarded as waste. This process is well known in the industry and is capable of producing good quality coatings, at least on the smaller size substrates. Various enhancements to this process have been made over the years, including recessed holding chucks, closed chamber spinning, and dispensing of the fluid while rotating the substrate. However, as substrate sizes continue to grow, the spin process faces significant obstacles (impractical to spin very large substrates/chambers, substrate stress/breakage, corner defects). In addition to these limitations, this process wastes a large amount of the expensive process materials used in display production. For these reasons, spin coating is generally not a viable process for large (Gen 5 and above) substrates.


EXTRUDE & SPIN:
This process com-bines the spin process with a “relatively simple” extrusion coat process. An extrusion die is moved relative to the substrate and is used to dispense a layer of fluid; the substrate is then spun (in a manner similar to the spin coat process) to achieve the final fluid layer thickness and uniformity. The extrusion process is typically performed by FAS’ “FAS-Coat” equipment set. For this process, the fluid layer that is deposited by the extrusion die is thicker than the final desired thickness, but the volume of fluid needed is lower than for the conventional spin coat so the cost of manufacturing is significantly lowered. Additionally, this process retains the familiarity and manufacturing acceptance of the spin coat process. This hybrid process has been used with both single station (extrude and spin in the same chamber) and dual station (separate the two process, generally to improve throughput) versions. Other trade names such as “slit and spin” are used to describe the same type of process, while “scan and spin” uses a multi-nozzle array instead of the extrusion die to distribute the fluid prior to spinning. Despite these enhancements, many of the disadvantages of the spin coating process remain and it is believed that this process (and its variants) will not be used significantly as substrates move beyond Gen 5.


FAS' EXTRUSION COAT: 
The extrusion coat, or “pure extrusion” process, uses the die to directly dispense the process fluid onto the substrate at the desired final thickness and uniformity level. This involves controlling the movement of the die, and the dispensing of the fluid through the die, at very precise levels. The extrusion coat process is typically performed by FAS’ “FAS-Coat” equipment set. The pure extrusion process eliminates spin coating entirely, along with its disadvantages. In addition, there is no fundamental limitation in substrate size. Also compelling is the virtual elimination of process material waste, thus reducing manufacturing costs, for this process, to their minimum. Extrusion coating systems consume much less electricity than spin-based systems and they also eliminate the edge bead removal (EBR) process that is needed for spun-on films. The primary challenges for the extrusion process are the control of a number of critical parameters and the general acceptance of the process in a manufacturing environment, which has already started to occur. It is believed that extrusion coating will be the dominant coating technology as substrates transition through Gen 5 towards larger sizes.


OTHER COATING TECHNOLOGIES AND MATERIALS: 
In addition to the above listed coating techniques, which are used for coating photoresist, color filter, and other materials, other specialized methods are sometimes used for certain display applications. Roller coating is dominant in the coating of alignment layer polyimides; however, it is believed that extrusion is a potential replacement for this application. In addition, extrusion coating is the method of choice for applying the new oriented polymers that act as polarizers and have the potential to replace the expensive film-type polarizers currently used. Screen-printing is sometimes used for the application of glass frit materials for the manufacturing of PDP’s. Extrusion has been proven for this application as well, and for different types of frit compounds (depending on their use within the panel).