Method of manufacturing a flexible circuit electrode array with at least one tack opening

1. A method of making a flexible circuit electrode array comprising:

depositing a polymer base layer, hard enough to support metal traces;

depositing metal on said polymer base layer;

patterning said metal to form metal traces and metal electrodes;

depositing a polymer top layer on said polymer base layer and said metal traces preparing openings in said polymer top layer to expose said electrodes;

depositing a soft polymer layer, softer than said polymer base layer, over said polymer top layer including covering at least a portion of its edges, the soft polymer layer being a part of the final device and suitable to protect neural tissue from the flexible circuit;

preparing at least one first tack opening through said polymer base layer and said polymer top layer near said electrodes suitable for attaching said flexible circuit electrode array to a retina; and

forming a membrane of polymer softer than said polymer base layer around the first tack opening, and forming a second tack opening within, and smaller than, said first tack opening, through the membrane of polymer, the softer polymer reducing stress transmitted from a tack to the flexible circuit electrode array.

2. The method according to claim 1 , wherein said flexible circuit electrode array is made thinner around said tack opening forming said stress relief feature, as compared with material immediately surrounding said stress relief feature.

3. The method according to claim 1 , wherein said stress relief feature is said tack opening surrounded by a flat or hemisphere shaped membrane.

4. The method according to claim 1 , further comprising the step of molding a portion of said flexible circuit electrode array containing electrodes in an approximately convex spherical curve, to match the curvature of a retina.