Selective metal etch technique

摘要

A method of forming a flexible printed wiring board having a metal substrate includes the steps of etching through-holes in the metal substrate by means of an etch resistant ferro electric mask placed over the substrate and employing a viscous sealant such as polyethylene or polypropylene glycol between the mask and the substrate. The mask is held to the substrate with the sealant therebetween by means of a magnetic field. The substrate is then treated with a ferric chloride etch solution to etch away the desired through-holes in the metal substrate. Thereafter, the substrate may be coated with a polymeric coated by means of fluidized bed or electrostatic coating techniques as taught in the prior art.