Roll-to-roll electroless plating system with spreader duct

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 substrate from an input roll though the plating solution in the pan along a web advance direction and to a take-up-roll, the web of substrate including a first edge and a second edge that is separated from the first edge along a cross-track direction perpendicular to the web advance direction, wherein a plating substance in the plating solution is plated onto predetermined locations on a surface of the web of substrate as it is advanced through the plating solution in the pan;

a pan-replenishing pump for moving plating solution from the sump to an inlet of the pan through a pipe connected to an outlet of the pan-replenishing pump, the inlet of the pan being located in proximity to a bottom of the pan below the web of substrate; and

a spreader duct including a channel that is in fluidic communication with the inlet of the pan, wherein the channel is positioned below the web of substrate and includes at least one outlet disposed beyond the first edge or the second edge of the web of substrate, and wherein the channel has no outlets disposed immediately below the web of substrate.

2. The roll-to-roll electroless plating system of claim 1 , further including an inert gas source that is configured to inject bubbles of a gas into the plating solution upstream of the inlet of the pan.

3. The roll-to-roll electroless plating system of claim 2 wherein the gas is air, oxygen or an inert gas.

4. The roll-to-roll electroless plating system of claim 3 , wherein the inert gas is nitrogen.

5. The roll-to-roll electroless plating system of claim 1 , wherein the plating substance is copper.

6. The roll-to-roll electroless plating system of claim 1 , wherein the channel includes a first end and a second end that is displaced from the first end by a distance that is greater than a substrate width between the first edge and the second edge of the web of substrate.

7. The roll-to-roll electroless plating system of claim 1 , wherein the web of substrate is oriented horizontally within the pan of plating solution.

8. The roll-to-roll electroless plating system of claim 1 further including an oxygen sensor.

9. The roll-to-roll electroless plating system of claim 8 further including a controller, wherein the controller is configured to receive data from the oxygen sensor and to control a rate of injection of a gas into the plating solution in response to the data received from the oxygen sensor.

10. The roll-to-roll electroless plating system of claim 1 , wherein a cross-section of the channel of the spreader duct is non-uniform.

11. The roll-to-roll electroless plating system of claim 1 , wherein one or more outlets of the channel are oriented in a direction which is not parallel to the web advance direction and not parallel to the cross-track direction.

12. The roll-to-roll electroless plating system of claim 1 further including a manifold, wherein the manifold is fluidically connected to the channel of the spreader duct and has a plurality of manifold outlets distributed along the web advance direction beyond the first edge or the second edge of the web of substrate.

13. The roll-to-roll electroless plating system of claim 1 , wherein the predetermined locations include features printed onto the web of substrate with ink including a catalyst for plating.