Alkalinity characterization of permanganate etching of polycyanate ester resins

The effects of permanganate etch alkalinity on the surface preparation quality for a carbon fiber---polycyanate ester resin weave is examined using copper plating and subsequent stud pull adhesion test. A sodium permanganate etchant with alkalinity varying from 0 to 80 grams per liter of sodium hydroxide (NaOH) is used during the surface preparation. Copper is plated 30 mu-inches thick. Based upon adhesion strength results, variations of the alkalinity of the permanganate etch used in preparation of the surface exhibits three distinct regions of response. Etch alkalinity below 15 grams per liter NaOH produces poor adhesion (600 PSI). A transitional region where adhesion improves with increased etch alkalinity is observed between 15 and 40 grams per liter NaOH. Above 40 grams per liter NaOH, adhesion strength averages 1500 PSI and is independent of the etch alkalinity. Included in this work is a surface preparation and plating procedure.