Biocompatible bonding method and electronics package suitable for implantation

• US 7,142,909 B2
• Filed: 09/06/2002
• Issued: 11/28/2006
• Est. Priority Date: 04/11/2002
• Status: Active Grant

• Current Assignee: Cortigent Incorporated
• Original Assignee: Second Sight Medical Products, Inc.
• Inventors: Neysmith, Jordan, Greenberg, Robert J., Zhou, Dao Min, Talbot, Neil, Ok, Jerry
• Primary Examiner(s): Getzow, Scott M.
• Application Number:
  US10/236,396
• Publication Number:
  US 20030233134A1
• Time in Patent Office: 1,544 Days
• Field of Search: 257/778, 607/2, 607/54
• US Class Current: 607/2
• CPC Class Codes: A61N 1/0543 Retinal electrodes
• CPC Class Codes: A61N 1/36046 of the eye
• CPC Class Codes: A61N 1/375 Constructional arrangements, e.g. casings
• CPC Class Codes: A61N 1/3758 Packaging of the components within the casing
• CPC Class Codes: H01L 21/563 Encapsulation of active face of flip-chip device, e.g. underfilling or underencapsulation of flip-chip, encapsulation preform on chip or mounting substrate
• CPC Class Codes: H01L 2224/0557 the external layer being disposed on a via connection of the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/05571 the external layer being disposed in a recess of the surface
• CPC Class Codes: H01L 2224/05573 Single external layer
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/13169 Platinum [Pt] as principal constituent
• CPC Class Codes: H01L 2224/13178 Iridium [Ir] as principal constituent
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/16227 the bump connector connecting to a bond pad of the item
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/73204 the bump connector being embedded into the layer connector
• CPC Class Codes: H01L 2224/81469 Platinum [Pt] as principal constituent
• CPC Class Codes: H01L 2224/81478 Iridium [Ir] as principal constituent
• CPC Class Codes: H01L 2224/81815 Reflow soldering
• CPC Class Codes: H01L 23/49827 Via connections through the substrates, e.g. pins going through the substrate, coaxial cables H01L23/49822, H01L23/49833, H01L23/4985, H01L23/49861 take precedence
• CPC Class Codes: H01L 23/49838 Geometry or layout
• CPC Class Codes: H01L 23/4985 : Flexible insulating substrates H01L23/49572 and H01L23/49855 take precedence
• CPC Class Codes: H01L 24/81 : using a bump connector
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01046 : Palladium [Pd]
• CPC Class Codes: H01L 2924/01077 : Iridium [Ir]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/1461 : MEMS
• CPC Class Codes: H05K 1/028 : Bending or folding regions of flexible printed circuits H05K1/0283 takes precedence
• CPC Class Codes: H05K 1/0306 : Inorganic insulating substrates, e.g. ceramic, glass
• CPC Class Codes: H05K 1/09 : Use of materials for the conductive, e.g. metallic pattern
• CPC Class Codes: H05K 1/111 : Pads for surface mounting, e.g. lay-out
• CPC Class Codes: H05K 1/113 : Via provided in pad; Pad over filled via
• CPC Class Codes: H05K 1/115 : Via connections; Lands around holes or via connections H05K1/112 takes precedence
• CPC Class Codes: H05K 1/189 : characterised by the use of a flexible or folded printed circuit H05K3/326 takes precedence
• CPC Class Codes: H05K 13/0469 : by applying a glue or viscous material
• CPC Class Codes: H05K 2201/09127 : PCB or component having an integral separable or breakable part
• CPC Class Codes: H05K 2201/1028 : Thin metal strips as connectors or conductors
• CPC Class Codes: H05K 2201/10287 : Metal wires as connectors or conductors
• CPC Class Codes: H05K 2201/10295 : Metallic connector elements partly mounted in a hole of the PCB
• CPC Class Codes: H05K 2201/10977 : Encapsulated connections applying non-metallic protective coatings for encapsulating mounted components H05K3/284
• CPC Class Codes: H05K 2203/05 : Patterning and lithography; Masks; Details of resist
• CPC Class Codes: H05K 2203/06 : Lamination
• CPC Class Codes: H05K 2203/0733 : Method for plating stud vias, i.e. massive vias formed by plating the bottom of a hole without plating on the walls
• CPC Class Codes: H05K 2203/09 : Treatments involving charged particles
• CPC Class Codes: H05K 2203/107 : Using laser light shaping a substrate by laser ablation H05K3/0026
• CPC Class Codes: H05K 2203/1446 : Treatment after insertion of lead into hole, e.g. bending, cutting, caulking or curing of adhesive but excluding soldering
• CPC Class Codes: H05K 3/10 : in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
• CPC Class Codes: H05K 3/188 : by direct electroplating
• CPC Class Codes: H05K 3/305 : Affixing by adhesive
• CPC Class Codes: H05K 3/321 : by conductive adhesives
• CPC Class Codes: H05K 3/328 : by welding
• CPC Class Codes: H05K 3/3436 : having an array of bottom contacts, e.g. pad grid array or ball grid array components
• CPC Class Codes: H05K 3/361 : Assembling flexible printed circuits with other printed circuits
• CPC Class Codes: H05K 3/4015 : using auxiliary conductive elements, e.g. pieces of metal foil, metallic spheres
• CPC Class Codes: H05K 3/4038 : Through-connections; Vertical interconnect access [VIA] connections H05K3/403, H05K3/42 take precedence
• CPC Class Codes: H05K 3/4084 : by deforming at least one of the conductive layers
• CPC Class Codes: H05K 3/423 : characterised by electroplating method
• CPC Class Codes: H05K 3/4644 : by building the multilayer layer by layer, i.e. build-up multilayer circuits making via holes in the insulating layers H05K3/0011; special circuit boards as base or core whereon the multilayer is built H05K3/4602
• CPC Class Codes: H05K 3/4652 : Adding a circuit layer by laminating a metal foil or a preformed metal foil pattern H05K3/4647 takes precedence
• CPC Class Codes: H05K 3/4691 : Rigid-flexible multilayer circuits comprising rigid and flexible layers, e.g. having in the bending regions only flexible layers

Abstract

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.

Claims

1. An implantable device comprising:

a substrate containing at least one electrically conductive feedtbrough attached to an electrically conductive routing on at least one side of said substrate;

a flexible assembly comprised of a first flexible electrically insulating substrate, a second flexible electrically insulating substrate, and at least one bond pad between said first and said second flexible electrically insulating substrates;

said first flexible electrically insulating substrate defining at least one hole that passes through said first flexible electrically insulating substrate, wherein said hole is aligned with said routing;

said second flexible electrically insulating substrate defining at least one hole that passes through said first flexible electrically insulating substrate, wherein said hole is aligned with said routing;

said at least one bond pad defining a hole therethrough, wherein said hole is aligned with said routing; and

wherein said substrate and said flexible assembly are bonded together with a deposited rivet.

2. The implantable device according to claim 1 wherein a biocompatible adhesive bonds said substrate and said flexible assembly.

3. The implantable device according to claim 1 wherein said rivet comprises a biocompatible material.

4. The implantable device according to claim 1 wherein said rivet comprises platinum or a platinum alloy.

5. The implantable device according to claim 1 wherein said deposited rivet is formed by electrochemical deposition.

6. The implantable device according to claim 5 wherein said electrochemical deposition is accomplished at a current density of 50 to 2000 mA/cm².

7. The implantable device according to claim 5 wherein said electrochemical deposition is accomplished by pulse current control.

8. The implantable device according to claim 1 wherein said flexible assembly comprises polyimide.

9. The implantable device according to claim 1 wherein said substrate comprises a biocompatible ceramic.

10. The implantable device according to claim 9 wherein said biocompatible ceramic comprises alumina.

11. The implantable device according to claim 1 wherein said substrate is rigid.

12. The device according to claim 1 wherein said substrate is an electrically insulated integrated circuit.

13. The device according to claim 1 wherein said flexible assembly is a thin integrated circuit.

14. The device according to claim 1 wherein:

at least a part of said substrate forms an electronics control unit; and

said electronics control unit encapsulates electronics.

15. The device according to claim 1, comprising:

a platinum layer electrochemically deposited on said substrate wherein said layer has a thickness greater than 5 microns and a Vickers hardness greater than 10.

16. The device according to claim 15, wherein said substrate is platinum.

17. The device according to claim 15, wherein said platinum layer is fractal.

18. The device according to claim 15, wherein said platinum layer has a thickness greater than 10 microns.

19. The device according to claim 15, wherein said platinum layer is biocompatible.

20. The device according to claim 15, wherein said platinum layer does not contain lead.

21. The device according to claim 15, wherein said platinum layer consists essentially of pure platinum.

22. The device according to claim 15, wherein said platinum layer has an adhesive strength, as measured by scratch test, greater than 35 millinewtons critical load.

23. The device according to claim 15, wherein said platinum layer electrochemically deposited on said substrate is accomplished at a current density that is selected based on a hole diameter defined by said substrate.

24. The device according to claim 15 further comprising:

a first electrically insulating layer deposited on a first side of said substrate; and

a second insulating layer deposited on a second side of said electrically conductive substrate wherein said second insulating layer defines a hole wherein said platinum layer is electrochemically deposited.

25. The device according to claim 15, wherein said device is suitable for implantation within a living body.

26. The device according to claim 15, wherein said device forms an electrode.

27. A method of making a device, according to claim 1 comprising:

said substrate at least a portion of which is electrically conductive; and

electrochemically depositing a layer of platinum greater than one micron thick, with a Vickers hardness greater then ten on said electrically conductive portion.

28. The method of claim 27 further comprising the step of selecting a charge density for electrochemically depositing that is proportional to the area of said electrically conductive portion.

29. The method of claim 27 wherein said electrochemically deposited layer is greater then ten microns thick.

30. The method of claim 27 wherein said step of electrochemically depositing uses a current density, in milliamps per square centimeter, equal to 19572x⁻

1.46, where x is the diameter in microns of said electrically conductive portion of said substrate.

31. The method according to claim 27 of electrochemically depositing a platinum layer, comprising:

electroplating the surface of a conductive substrate at a rate such that the particles of platinum form on the conductive substrate faster than necessary to form shiny platinum and slower than necessary to form platinum gray;

aligning an anode and a cathode;

immersing said anode and cathode in an electrochemical bath; and

plating said platinum layer.