Biocompatible electroplated interconnection bonding method and electronics package suitable for implantation
The invention is directed to a method of bonding a hermetically sealed electronics package to an electrode or a flexible circuit and the resulting electronics package that is suitable for implantation in living tissue, such as for a retinal or cortical electrode array to enable restoration of sight to certain non-sighted individuals. The hermetically sealed electronics package is directly bonded to the flex circuit or electrode by electroplating a biocompatible material, such as platinum or gold, effectively forming a plated rivet-shaped connection, which bonds the flex circuit to the electronics package. The resulting electronic device is biocompatible and is suitable for long-term implantation in living tissue.
1. A method of bonding for implantation of a substrate to a flexible assembly, said method comprising the steps of:
aligning said substrate and said flexible assembly establishing a common alignment for a contact on said substrate and contact pads on said flexible assembly; and
bonding said flexible assembly to said substrate by electroplating bonding between said contacts and said pads, wherein said electroplating bonding step includes plating first at a slow rate followed by plating at a fast rate.
2. The method according to claim 1 further comprising the step of applying an electrically non-conductive adhesive between said substrate and said flexible assembly.
3. The method of claim 1 wherein said step of electroplating bonding further comprises selecting a plating solution containing 20 to 200 millimoles gold sulphite in 50 to 500 millimoles of support electrolyte comprises disodium hydrogen phosphate, alkali sulfite or sulfuric acid, or mixtures thereof.
4. The method of claim 1 wherein said electroplating bonding comprises electroplating bonding at a plating temperature of 24° to 26° C.
5. The method of claim 1 wherein said electroplating bonding comprises electroplating bonding at a voltage range of −0.7 volts to −1.25 volts.
6. The method of claim 1 wherein said electroplating bonding further comprises:
applying −0.75 volts to −0.90 volts to plate a thin and dense electroplated layer; and
increasing said plating rate includes applying −1.00 volts to −1.025 volts to provide a less dense layer.
7. The method of claim 1 , wherein said electroplating bonding step is electroplating platinum.
8. The method of claim 1 , wherein said plating rate first at a slower rate followed by plating at a faster rate is controlling said rate at a constant voltage.