Computer simulation of flow balance in the die of slot coater: Part 1: Land geometry

Coating operations such as spin coating, curtain coating, role coating, slide coating, slot coating, and etc. are dated from long time ago and still considered very important processing. Slot coating is considered very important specially for the manufacturing of liquid crystal display parts. Photo resistant is coated on the glass and is sent to next process to make TFT board. Coating quality such as uniformity of coating thickness can be divided into two categories, which are machine direction quality and transverse direction quality. Machine direction quality is related to die lip design and operation conditions whereas the transverse direction quality is related to flow uniformity inside of the die. The flow uniformity is governed by flow balance in the die. The most important design factors for the inside die geometry are manifold and land. Through this study the flow balance according to the land design has been examined by computer simulation. The parameters for land design are length and shape. Exit velocity at the outlet of die is different from land designs. The best land design has been investigated in this study.