Roll-to-roll electroplating photovoltaic films

Abstract

The present invention provides methods of electroplating a film or films onto a top surface of a continuously moving roll-to-roll sheet. In one aspect, the invention includes continuously electroplating a film onto a conductive surface using an electroplating unit as the roll-to-roll sheet moves therethrough.

1 . An electrodeposition apparatus for electrodepositing a material film from an electrodeposition solution onto a front surface of a flexible workpiece as the flexible workpiece is advanced through the apparatus in a roll to roll manner, the apparatus comprising:
 an electrodeposition unit to electrodeposit the material film onto the front surface of the flexible workpiece as the flexible workpiece is advanced through the electrodeposition unit, the electroplating unit comprising:
 a solution chamber having a peripheral wall configured for retaining the electrodeposition solution at a predetermined level; 
 at least one solution inlet to receive a first flow of the electrodeposition solution wherein the at least one solution inlet is positioned adjacent an upper end of the peripheral wall and below the predetermined level of the electrodeposition solution; 
 at least one flow regulator attached to the at least one solution inlet to transform the first flow into a second flow of the electrodeposition solution and deliver the second flow into the solution chamber; and 
 an entrance opening and an exit opening positioned at a lower end of the peripheral wall so that the flexible workpiece is advanced through the electrodeposition solution by entering from the entrance opening and exiting through the exit opening of the solution chamber; 
   an anode plate positioned in the solution chamber between the flexible workpiece and the at least one solution inlet, wherein the front surface of the flexible workpiece is positioned across from the anode plate as the flexible workpiece is advanced through the solution chamber;   a support mechanism to support the flexible workpiece within the solution chamber as the flexible workpiece is advanced therethrough, the support mechanism comprising:
 a first support member positioned outside the solution chamber and adjacent the entrance opening, the first support member including a first roller contacting a back surface along the width of the flexible workpiece, and a second roller having end portions and a central portion, wherein the end portions contact only edge regions of the front surface, and wherein the central portion extends over a selected region located between the edge regions while not contacting the selected region thereby forming a first gap between a surface of the selected region and the central portion of the second roller, wherein a first leak flow leaking through the entrance opening is flowed out through the first gap of the first support member; and 
 a second support member positioned outside the solution enclosure and adjacent the exit opening, the second support member including a first roller contacting a back surface along the width of the flexible workpiece, and a second roller having end portions and a central portion, wherein the end portions contact only the edge regions of the front surface, and wherein the central portion extends over the selected region located between the edge regions while not contacting the selected region thereby forming a second gap between the surface of the selected region and the central portion of the second roller, wherein a second leak flow leaking through the exit opening is flowed out through the second gap of the second support member. 
   
     
     
         2 . The apparatus of  claim 1 , wherein the support mechanism further includes a first auxiliary roller positioned before the first support member and a second auxiliary roller positioned after the second support member, wherein the first and the second auxiliary rollers contact only the back surface of the flexible workpiece. 
     
     
         3 . The apparatus of  claim 2 , wherein the first and second auxiliary rollers are horizontally aligned with the first and second support members respectively so that the workpiece travels in a horizontal plane between the first auxiliary roller and the first support member and between the second support member and the second auxiliary roller. 
     
     
         4 . The apparatus of  claim 2 , wherein the first and second auxiliary rollers are aligned in an angled relationship with the first and second support members respectively so that the workpiece travels in a downwardly angled plane between the first auxiliary roller and the first support member and in an upwardly angled plane between the second support member and the second auxiliary roller. 
     
     
         5 . The apparatus of  claim 1  further including a solution container connected to the at least one solution inlet by solution conduits. 
     
     
         6 . The apparatus of  claim 5 , wherein the electroplating chamber further includes a solution outlet to flow a third flow of the electrodeposition solution out of the solution chamber, wherein the third flow is flowed into the solution container. 
     
     
         7 . The apparatus of  claim 1 , further including a moving assembly of the apparatus to hold and linearly move the flexible workpiece through electrodeposition unit and the support mechanism, wherein the moving assembly comprises a feed spool to unwrap and feed unprocessed sections of the flexible workpiece into the apparatus and a take-up spool to receive processed portions and wrap the processed portions there around. 
     
     
         8 . The apparatus of  claim 1 , wherein the at least one flow regulator delivers the second flow parallel to the front surface of the flexible workpiece. 
     
     
         9 . The apparatus of  claim 1 , wherein the at least one flow regulator is a porous nozzle covering the at least one solution inlet. 
     
     
         10 . The apparatus of  claim 1 , wherein the at least one flow regulator is positioned between the anode plate and the predetermined level of the electrodeposition solution. 
     
     
         11 . The apparatus of  claim 10 , wherein the at least one flow regulator has an elongated body extended into the solution chamber and parallel to the surface of the flexible workpiece. 
     
     
         12 . The apparatus of  claim 11 , wherein the elongated body includes openings to flow the second flow into the solution chamber. 
     
     
         13 . An electrodeposition system for depositing material film on a continuous moving web, the system comprising:
 a chamber that defines an inner volume that receives an electrodeposition solution, wherein the chamber has a first and a second end, and wherein the chamber includes a first and a second web opening adjacent a first end of the chamber so that the web can be transported through the chamber between the first and the second web openings;   an anode positioned in a first location within the chamber, wherein a portion of the web that is positioned between the first and second web openings defines a cathode that corresponds to the anode so that electrical potential therebetween results in electrodeposition of the film on the web as the web moves through the chamber; and   a solution supply system that provides solution to the chamber to replace solution that is lost or removed from the chamber, wherein the solution supply system includes a flow regulator that reduces the pressure of the solution being provided to the chamber so as to reduce the turbulence of the electrodeposition solution adjacent the cathode.   
     
     
         14 . The system of  claim 13 , wherein the solution supply system includes an inlet that is located so that the anode is interposed between the inlet and the cathode. 
     
     
         15 . The system of  claim 14 , wherein the inlet is positioned adjacent the second end of the chamber at a distance selected so that the introduction of the electrodeposition solution into the chamber does not disrupt substantially laminar flow of the solution adjacent the portion of the web comprising the cathode. 
     
     
         16 . The system of  claim 15 , wherein the inlet with the flow regulator is positioned approximately 4.5 to 19 inches from the portion of the web forming the cathode. 
     
     
         17 . The system of  claim 16 , wherein the flow regulator and the positioning of the inlet reduces the turbulence of the electrodeposition solution adjacent the portion of the web forming the cathode such that the Reynolds number of that solution is below 2000. 
     
     
         18 . The system of  claim 17 , wherein the Reynolds number is the range of approximately 100 to 1000. 
     
     
         19 . The system of  claim 13 , wherein the flow regulator receives the electrodeposition solution through a first opening and then discharges the electrodeposition solution into the chamber via a plurality of outlets having a greater area than the first opening to thereby reduce the pressure of the electrodeposition solution being introduced into the chamber. 
     
     
         20 . The system of  claim 19 , wherein the first opening and the second opening are positioned orthogonally to each other. 
     
     
         21 . The system of  claim 13 , further comprising at least one web support system positioned proximate at least one of the web openings of the chamber. 
     
     
         22 . The system of  claim 21 , wherein the web support system includes a first surface that supports a first side of the continuous web and a second member that engages with a portion of the second side of the continuous web that is to receive the electrodeposited film. 
     
     
         23 . The system of  claim 22 , wherein the second member comprises a roller that defines a central depression so that the second member engages with the second side of the continuous web at the edges of the web. 
     
     
         24 . The system of  claim 23 , wherein the central depression defines a gap that allows excess electrodeposition solution that is escaping the chamber via the web opening in the chamber to be channeled away from the chamber. 
     
     
         25 . The system of  claim 24 , wherein the at least one web support system comprises a first and a second web support system that is positioned adjacent the first and second web openings in the chamber.