Flexible Circuit Electrode Array for Improved Layer Adhesion

Abstract

The present invention is a flexible circuit electrode array for improved layer adhesions where the metal conductors overlap the polymer insulator. The steps to build the flexible circuit are as follows. Deposit a base polymer layer. Deposit a conductive trace over the base polymer layer. Deposit a top polymer layer over the trace and prepare a void in the top polymer layer smaller than the surface of the trace. Deposit an electrode on the trace through the void with a periphery larger than, and overlapping the void.

1 . A flexible circuit electrode array comprising:
 a base polymer layer;   a plurality of conductive traces deposited on the base polymer layer;   a top polymer layer deposited on the base polymer layer and the traces, and defining voids;   the conductive traces arranged on the base polymer layer to follow the shape of the base polymer layer without sharp turns more than about 45° in the trace pattern; and   a plurality of electrodes connected to the conductive traces through the voids.   
     
     
         2 . The flexible circuit electrode array according to  claim 1 , wherein the conductive traces are arranged to avoid an attachment point. 
     
     
         3 . The flexible circuit electrode array according to  claim 1  wherein base polymer layer and top polymer layers contain polyfluorocarbons, polyethylene, polypropylene, silicone, polyamide, polyimide, liquid crystal polymer, poly-paraxylylene, polyaryletherketone and/or derivatives and/or mixtures thereof. 
     
     
         4 . The flexible circuit electrode array according to  claim 1 , wherein the conductive traces contains a base conducting layer, an intermediate conducting layer and a top conducting layer. 
     
     
         5 . The flexible circuit electrode array according to  claim 4 , wherein the intermediate conducting layer contains platinum, tantalum, iridium, palladium, rhodium, rhenium, gold, chrome, molybdenum, or carbon, or an alloy thereof or a combination of two or more alloys or metal layers thereof. 
     
     
         6 . The flexible circuit electrode array according to  claim 4 , wherein the base conducting layer and the top conducting layers contain titanium, and the intermediate conducting layer contains platinum whereby the trace forms a titanium/platinum/titanium film stack. 
     
     
         7 . The electrode array according to  claim 1  wherein the electrodes comprise a surface coating, the surface coating having at least 5 times the surface area and less than 500 times the surface area of that for the corresponding surface area resulting from the basic geometric shape of the electrodes. 
     
     
         8 . The flexible circuit electrode array according to  claim 1  wherein the electrodes comprises a surface coating, the surface coating being biocompatible. 
     
     
         9 . The flexible circuit electrode array according to  claim 1  wherein the electrodes comprise a surface coating, the surface coating comprising platinum having a fractal configuration, titanium nitride, iridium oxide, or mixtures thereof 
     
     
         10 . The flexible circuit electrode array according to  claim 1 , wherein the top polymer layer and the base polymer layer are made of different polymers. 
     
     
         11 . The flexible circuit electrode array according to  claim 10 , wherein the top polymer layer is made of a polymer softer than the polymer of the base polymer layer. 
     
     
         12 . The flexible circuit electrode array according to  claim 11 , wherein the base polymer layer is made of polyimide and the top polymer layer is made of silicone. 
     
     
         13 . The flexible circuit electrode array according to  claim 1 , wherein the conductive traces separate the electrodes from the base polymer layer. 
     
     
         14 . The flexible circuit electrode array according to  claim 1 , wherein the electrodes protrudes from the top polymer layer. 
     
     
         15 . The flexible circuit electrode array according to  claim 1 , wherein the electrodes are thicker than the traces. 
     
     
         16 . The flexible circuit electrode array according to  claim 1 , wherein the traces are wider at the electrodes than it is along the rest of its length.