Abstract: The present invention relates to methods of etching polyimide from a substrate and to the etched substrates prepared according to such methods. In one embodiment, the present invention provides a method of etching polyimide from a substrate, comprising the steps of: providing a basic bath; ultrasonically agitating said basic bath; exposing said substrate containing polyimide to said basic bath; rinsing said substrate with hot water; optionally repeating the aforementioned steps at least once; and recovering an etched substrate.

Abstract: A system for filtering solid-containing plating waste comprises a reusable filter media belt that travels in a continuous loop between a filter tray, where filtration takes place, and a multi-compartmented cleaning tank where the belt is cleaned for reuse. Each compartment in the tank is substantially closed at its lower end, and open at its upper end. The belt travels in and out of each of the tank compartments in sequence, being subjected to a liquid cleaning treatment in each by contacting sprays and/or bath immersion before being returned to the filter tray for reuse. A wringer is provided at the top of each compartment through which the belt passes before proceeding to the next compartment in order to isolate the treatment liquids from each other.