Roll-to-roll electroless plating system with low dissolved oxygen content

Abstract

A roll-to-roll electroless plating system including a sump containing a first volume of a plating solution, and a pan containing a second volume of the plating solution, the second volume being less than the first volume. A web advance system advances a web of media though the plating solution in the pan, wherein a plating substance in the plating solution is plated onto predetermined locations on a surface of the web of media. A pan-replenishing pump moves plating solution from the sump to the pan through a pipe. A distribution system injects an inert gas into the plating solution to reduce the amount of dissolved oxygen.

1 . A roll-to-roll electroless plating system, comprising:
 a sump containing a first volume of a plating solution;   a pan containing a second volume of the plating solution, the second volume being less than the first volume;   a web advance system for advancing a web of media from an input roll though the plating solution in the pan along a web advance direction and to a take-up-roll, wherein a plating substance in the plating solution is plated onto predetermined locations on a surface of the web of media as it is advanced through the plating solution in the pan;   a pan-replenishing pump for moving plating solution from the sump to the pan through a pipe connected to an outlet of the pan-replenishing pump; and   a distribution system for injecting an inert gas into the plating solution.   
     
     
         2 . The roll-to-roll electroless plating system of  claim 1 , wherein the distribution system is configured to inject micro-bubbles of the inert gas into the plating solution, wherein the micro-bubbles have a diameter between about one micron and one millimeter. 
     
     
         3 . The roll-to-roll electroless plating system of  claim 1 , wherein the plating substance is copper, silver, nickel or palladium. 
     
     
         4 . The roll-to-roll electroless plating system of  claim 1 , wherein the inert gas is nitrogen or argon. 
     
     
         5 . The roll-to-roll electroless plating system of  claim 1 , wherein the distribution system is configured to inject the inert gas into the plating solution in the sump. 
     
     
         6 . The roll-to-roll electroless plating system of  claim 1 , further including a recirculation system including:
 a recirculation pump including an inlet and an outlet;   an inlet line for moving plating solution from the sump to the pump inlet; and   an outlet line for returning plating solution from the pump outlet to the sump.   
     
     
         7 . The roll-to-roll electroless plating system of  claim 6 , wherein the distribution system is configured to inject the inert gas into the inlet of the recirculation pump. 
     
     
         8 . The roll-to-roll electroless plating system of  claim 6 , further comprising a filter in the outlet line. 
     
     
         9 . The roll-to-roll electroless plating system of  claim 6 , further including an injector downstream of the recirculation pump outlet, the injector including:
 a converging tube segment having a diameter that decreases with distance from the recirculation pump outlet;   a diverging tube segment downstream of the converging tube segment, the diverging tube segment having a diameter that increases with distance from the converging tube segment;   a throat formed at a junction of the converging tube segment and the diverging tube segment; and   an inlet for the inert gas in proximity to the throat.   
     
     
         10 . The roll-to-roll electroless plating system of  claim 1 , wherein the distribution system includes a plumbing assembly having a plurality of distributed orifices for injecting the inert gas into the plating solution for providing bubbles of inert gas into the sump. 
     
     
         11 . The roll-to-roll electroless plating system of  claim 10 , wherein the plumbing assembly is disposed proximate to a bottom of the sump. 
     
     
         12 . The roll-to-roll electroless plating system of  claim 1 , wherein the distribution system is configured to inject the inert gas into the pipe through which plating solution is moved from the sump to the pan. 
     
     
         13 . The roll-to-roll electroless plating system of  claim 12 , further including an injector downstream of the pan-replenishing pump outlet, the injector including:
 a converging tube segment having a diameter that decreases with distance from the pan-replenishing pump outlet;   a diverging tube segment downstream of the converging tube segment, the diverging tube segment having a diameter that increases with distance from the converging tube segment;   a throat formed by a junction of the converging tube segment and the diverging tube segment; and   an inlet for the inert gas in proximity to the throat.   
     
     
         14 . The roll-to-roll electroless plating system of  claim 1 , further comprising an oxygen sensor. 
     
     
         15 . The roll-to-roll electroless plating system of  claim 14 , further comprising a controller, wherein the controller is configured to receive data from the oxygen sensor and to control a rate of injection of the inert gas into the plating solution in response to the data received from the oxygen sensor. 
     
     
         16 . The roll-to-roll electroless plating system of  claim 15 , wherein a dissolved oxygen content of the plating solution is controlled to be between 0.5 and 2 parts per million. 
     
     
         17 . The roll-to-roll electroless plating system of  claim 1 , further comprising a drain pipe extending from the pan into the the sump for draining plating solution from the pan to the sump, such that plating solution in the drain pipe is not exposed to air. 
     
     
         18 . The roll-to-roll electroless plating system of  claim 1 , wherein the sump further includes a sump cover. 
     
     
         19 . The roll-to-roll electroless plating system of  claim 1 , wherein the pan further includes a pan cover. 
     
     
         20 . The roll-to-roll electroless plating system of  claim 1 , wherein the distribution system further includes a static mixer. 
     
     
         21 . The roll-to-roll electroless plating system of  claim 1 , wherein the predetermined locations include features printed onto the web of media with ink including a catalyst for plating. 
     
     
         22 . An article having features that were plated using the roll-to-roll electroless plating system of  claim 1 . 
     
     
         23 . The article of  claim 22 , wherein at least some of the features have widths between 2 microns and 10 microns.