Method for increasing surface adhesion in polyetherimide substrates

Abstract

A process of enhancing surface adhesion of polyetherimides for metal plating includes contacting sulfuric acid with a surface of a polyetherimide substrate for a first dwell time to form a pre-etched polyetherimide substrate, contacting the pre-etched polyetherimide substrate with a mixture of sulfuric acid and periodate ions for a dwell time to form an oxidized polyetherimide surface, contacting the oxidized polyetherimide surface with an alkaline metal hydroxide solution for a third dwell time without rinsing between the applying steps or between the applying and contacting steps, where the polyetherimide is free of or includes a low volume percentage of reinforcement particles, and the process does not include contacting the polyetherimide substrate with nitric acid in any step.

What is claimed is: 
     
         1 . A process of enhancing surface adhesion of polyetherimides for metal plating, the process comprising:
 contacting sulfuric acid with a surface of a polyetherimide substrate for a first dwell time to form a pre-etched polyetherimide substrate;   contacting the pre-etched polyetherimide substrate with a mixture of sulfuric acid and periodate ions for a second dwell time to form an oxidized polyetherimide surface;   contacting the oxidized polyetherimide surface with an alkaline metal hydroxide solution for a third dwell time without rinsing between the applying steps or between the applying and contacting steps;   wherein the polyetherimide comprises a low volume percentage of reinforcement particles, and the process does not include contacting the polyetherimide substrate with nitric acid in any step.   
     
     
         2 . The process of  claim 1 , wherein the reinforcement particles comprise a metal, a metal oxide, a metal carbide, a metal nitride, a metal boride, carbon, carbon fibers, carbon nanotubes, graphene, fullerene, graphite, graphite fibers, glass, glass fibers, fiberglass, metal-coated glass fibers, metal-coated carbon fibers, metal-coated graphite fibers, talc, calcium silicate, silica, calcium carbonate, alumina, titanium dioxide, ferrite, mica, mixed silicates, or a mixture of any two or more thereof. 
     
     
         3 . The process of  claim 1 , wherein the reinforcement particles comprise glass fiber, fiberglass, a metal-coated fiber, a mineral filler, or a combination of any two or more thereof. 
     
     
         4 . The process of  claim 1 , wherein a concentration of the sulfuric acid is from 84 wt % to 97 wt %. 
     
     
         5 . The process of  claim 1 , wherein the first dwell time is from 2 to 30 minutes. 
     
     
         6 . The process of  claim 1 , wherein the second dwell time is from 4 to 30 minutes. 
     
     
         7 . The process of  claim 1 , wherein a concentration of alkaline metal hydroxide in the alkaline metal hydroxide solution is from 0.2 M to 1.0 M. 
     
     
         8 . The process of  claim 1 , wherein the third dwell time is a minimum time of 3 minutes.