Electroless plating process

Abstract

An electroless plating method for use in metal plating on a porous substrate is disclosed. It uses selective contact of the plating metal salt solution with a reducing solution on the activated surface on or inside the porous substrate. This electroless plating method in the setup is useful for unmanned, automatic operation resulting in almost 100% membrane (pure/composite) with substantially no pinholes or cracks.

1 . An electroless plating process for 100% membrane preparation using a porous substrate comprising the steps of:
 i. providing cleaned, sensitized and activated porous substrate selected from the group consisting of glass, sintered metal and ceramics;   ii. contacting first surface of the substrate as provided in step (i) with plating solution;   iii. contacting second surface which is located opposite to the first surface of the substrate as provided in step (i) with reducing solution;   iv. applying pressure to one of the said plating and reducing solutions causing permeation of the pressurized solution to the other side of the substrate resulting contact between plating solution and reducing solution thereby causing deposition of the metal on the substrate surface;   v. rinsing the metal deposited substrate surface with water and heat treating the same at predetermined temperature to obtain the metal plated surface.   
     
     
         2 . The electroless plating process as claimed in  claim 1 , wherein said process is characterized by contacting one surface of the substrate with plating solution and contacting second surface of substrate with reducing solution. 
     
     
         3 . The electroless plating process as claimed in  claim 1 , wherein the plating solution used is selected from metal salt solutions that can produce metal/metal alloy ions and can be reduced by reducing ion like hydrogen to produce metal. 
     
     
         4 . The electroless plating process as claimed in  claim 1 , wherein the reducing solution used is selected from solution that can produce a reducing ion like hydrogen that can reduce the metal salt solution to metal. 
     
     
         5 . The electroless plating process as claimed in  claim 1 , wherein the step of drying the metal deposited substrate comprises heat treating the same at a temperature in the range of 70 to 80° C. followed by annealing at temperature in the range of 350 to 370° C. to obtain plated metal substrate surface. 
     
     
         6 . The electroless plating process as claimed in  claim 1 , wherein the reducing solution used is selected from hydrazine, sodium hypophosphite or formaldehyde. 
     
     
         7 . The electroless plating process as claimed in  claim 1 , wherein said metal plated membrane is without any air leakage. 
     
     
         8 . A system for performing electroless plating process for plating of a porous substrate with metal as claimed in  claim 1 , wherein said system comprises:
 a. a compartment divided into a first section and a second section by a substrate to be plated with metal; each of the said first and the second section comprises
 i. an inlet for supplying plating solution and reducing solution respectively; 
 ii. an outlet for draining reacted solution; 
   b. a first burette containing the plating solution connected with the inlet of the first section;   c. a second burette containing the reducing solution connected with an inlet of the second section;   d. a pressurizing means connected with the anyone of the said first or the second burette.   
     
     
         9 . A system as claimed in  claim 7 , wherein the first section and the second section are securable with each other to define the said compartment. 
     
     
         10 . A system as claimed in  claim 7 , wherein the substrate is disposed between the first section and the second section when the said sections are secured with other.