Winter 1994

Electrolytic Etchant Regeneration

How fast the etching ratc is being reduced according to the dissolved metal quantity is demonstrated in fig.,..l. Regardless of the initial molarity of the FeCl3 etchant the etching rate goes down by about 1.5 um/min per 10 g/l of the dissolved metal A higher initial molarity is thus not equivalent to a more voluminous ~etching·reserve~. Thus, the use of ferric chloride as etch solution without any regeneration is problematic most of all regarding the following two points: 1.: -the permanendy decreasing FcCl3 concentration of the etch solution due to the change to FeCl2 during the etching process, 2. : -the comparatively low metal absorption of about 30 g/l in relation to a 3.8 molar FeCl3 so1ution.

A.Visser and M. Junker, University of Bremen