A car clutch including a clutch base formed with a seating part and an input-side ring gear. The improvement in the liquid phase process resides in effecting the fluorination of said borohydride salt in the presence of a reaction medium having an acidity between that of water and anhydrous HF. Portions of a plug may be removed during the wet etch to form overhanging spacers to provide further protection of the conductor during the dry etch.