Visiting Photochemical Machining

March 2000

Visiting Photochemical Machining

The photochemical machining or chemical milling industry is worth studying since it has advanced teclmologics which it shares with PWB filbrieation. This “niche technology,” as the German title ofReference 1 implies, deals with very demanding precision requirements and fine geometries. During a recent visit to photochemical machining shops I have seen more 2-3 mil (50-75 microo) feature work than in any ”high tech” PWB shop.

Photochemical machining has steadily expanded into electronic packaging. Examples are lead &ames (Ref. 2), EM! shielding, and flexible circuits that require etching or plating ofcircuits as well as etching of KaptonlJ) polyimide layers. This industry is using materials familiar to PWB fabricators, such as photoresists, developers, etchants, and strippers. Process equipment may be identical to PWB fabrication. but you might find morc tank processing than conveyorized spraying. and there arc industry-specifiG-process alterations, such as “barrel” plating.

Karl Dietz, DuPont Printed Circuit Materials