Multi-Pass Vacuum Coating Systems

Abstract

A multi-pass coating system and method for applying multiple coatings to substrates traversed through the system. The system includes at least one vacuum pump coupled to the system to establish a sub-atmospheric pressure within the system. The system also includes a least one coating zone where a coating layer is applied to the substrate and includes at least one transfer lock through which the substrates transition between atmospheric pressure outside the system and the sub-atmospheric pressure inside the system. To move the substrates through the system, the system includes a transport mechanism configured to move the substrates at least two times through the coating zone prior to the substrates being exited from the system.

1 . A multi-pass coating system for applying multiple coatings to substrates traversed through the system, the system comprising:
 at least one vacuum pump coupled to the system to establish a sub-atmospheric pressure within the system;   a plurality of zones including at least one coating zone where a coating layer is applied to the substrate;   the plurality of zones also including at least one transfer lock through which the substrates transition between atmospheric pressure outside the system and the sub-atmospheric pressure inside the system; and   a transport mechanism configured to move one or more substrates at least two times through the coating zone prior to the substrates exiting from the system.   
   
   
       2 . The multi-pass coating system of  claim 1  wherein the transport mechanism is configured to move the substrates through the coating zone in a first direction of movement followed by a reversal of the direction of movement and the moving of the substrates through the coating zone in a second direction. 
   
   
       3 . The multi-pass coating system of  claim 2  wherein one of the plurality of zones further comprises a take-up module as part of the transport mechanism, the take-up module reversing the direction of movement of the substrates within the system. 
   
   
       4 . The multi-pass coating system of  claim 3  wherein the take-up module is configured to receive, hold and dispense multiple substrates such that multiple substrates are capable of being located within the coating system at the same time. 
   
   
       5 . The multi-pass coating system of  claim 3  wherein the take-up module further comprises a cassette mechanism, the cassette mechanism being configured to individually receive and hold a plurality of substrates. 
   
   
       6 . The multi-pass coating system of  claim 1  wherein one of the plurality of zones further comprises a heating zone module including heaters configured to regulate temperature of the substrate prior to application of a coating layer to the substrate. 
   
   
       7 . The multi-pass coating system of  claim 1  wherein the transfer lock includes a take-up module as part of the transport mechanism, the take-up module reversing the direction of movement of the substrates within the system, the take-up module of the transfer lock being configured to receive, hold and dispense multiple substrates such that multiple substrates are capable of being located within the coating system at the same time. 
   
   
       8 . The multi-pass coating system of  claim 1  wherein the transfer lock is an intake transfer lock, the system also further comprises an out-take transfer lock, the intake and out-take transfer locks respectively being configured to receive substrates in the system and to exit substrates from the system. 
   
   
       9 . The multi-pass coating system of  claim 1  wherein the plurality of zones includes a recirculation module, the recirculation module configured to route substrates exiting from the coating zone back to re-enter the coating zone for the application of an additional coating layer. 
   
   
       10 . The multi-pass coating system of  claim 9  wherein the recirculation module is connected to a splitter module, the splitter module being configured to direct substrates to one of the recirculation module and an exit of the system, the recirculation module also being connected to a merge module, the merge module being configured to reintroduce substrates from the recirculation module back into a succession of substrates entering the coating zone. 
   
   
       11 . The multi-pass coating system of  claim 1  further comprising at least some of the modules having walls coupled with a cooling system, the cooling system being configured to actively cool the walls of the module so as to reduce thermal effects on substrates passing through module. 
   
   
       12 . A method for coating substrates with multiple coating layers, the method comprising the steps of:
 establishing a sub-atmospheric pressure within the system;   transferring each substrate from outside the coating system to inside the coating system though a transfer lock;   traversing a coating zone in a first direction of movement and applying a first coating layer to each substrate in the coating zone;   traversing the coating zone a second time and applying a second coating layer to each substrate in the coating zone; and   transferring each substrate from inside the coating system to outside the system through a transfer lock.   
   
   
       13 . The method of  claim 12  wherein the step of traversing the coating zone a second time is performed in a second direction of movement, the second direction of movement being different than the first direction of movement. 
   
   
       14 . The method of  claim 13  wherein the second direction of movement is opposite in direction to the first direction of movement. 
   
   
       15 . The method of  claim 12  wherein the step of traversing the coating zone a second time is performed in a second direction of movement, the second direction of movement being the same as the first direction of movement. 
   
   
       16 . The method of  claim 12  further comprising the step of reversing the direction of movement of the substrates through the system. 
   
   
       17 . The method of  claim 16  wherein the reversing step includes receiving and holding a plurality of substrates and then dispensing the substrates in the second direction. 
   
   
       18 . The method of  claim 12  wherein multiple substrates are moved through the system simultaneously. 
   
   
       19 . The method of  claim 12  further comprising the step of traversing the coating zone more than two times and applying more than two coating layers onto the substrates. 
   
   
       20 . The method of  claim 19  wherein the step of traversing the coating zone more than two times includes traversing the coating zone at least one time without applying a corresponding coating to the substrates. 
   
   
       21 . The method of  claim 12  further comprising the step of heating each substrate in a heating zone to a temperature suitable for coating.