Implantable electrical contact arrangement

Abstract

The invention relates to an implantable electrical contact arrangement which has at least one electrode element arrangement enclosed entirely by biocompatible, electrically insulating material and comprising at least one electrode surface that is directly or indirectly enclosed by the biocompatible, electrically insulating material, the electrode element arrangement having a stack-shaped layer composite which has a metallisation layer at least on a ceramic substrate over an adhesion promoter layer. The invention is characterised in that: the stack-shaped layer composite is bonded to a passivation layer such that covalent bonds are formed, and is otherwise completely encased by said passivation layer, except for at least one surface area of the metallisation layer facing away from the layer composite; the passivation layer has a passivation layer surface which faces away from the stack-shaped layer composite and to which the biocompatible, electrically insulating material is directly or indirectly adjacent; and the passivation layer is deposited on the stack-shaped layer composite by means of plasma-enhanced chemical vapour deposition (PECVD), physical vapour deposition (PVD), or wet chemical coating.

Description

[0001] Implantable electrical contact arrangement

[0002] Technical area

[0003] Described is an implantable electrical contact arrangement comprising at least one electrode body arrangement made entirely of biocompatible, electrically insulating material, with at least one electrode surface directly or indirectly surrounded by the biocompatible, electrically insulating material, wherein the electrode body arrangement comprises a stacked layer composite having a metallization layer over an adhesion promoter layer at least on a ceramic substrate.

[0004] A particular challenge in the manufacture and design of implantable electrical contact arrangements, via which electrical conductors or conductor structures are electrically connected to one another, is preventing the penetration of water or moisture into and / or through the material interfaces contained within an electrical contact arrangement. Contact with water on electrically conductive conductor and electrode structures, usually made of metallic material, leads to irreversible degradation and a related impairment of the electrical energy and signal transmission properties. Furthermore, a permanently moist environment leads to detachment phenomena between the metallic structures contained within the electrical contact arrangement and the immediately surrounding surfaces, usually made of polymeric material, which ultimately reduces the service life of such contact arrangements.

[0005] State of the art

[0006] From the article by Patrick Kiele et al., “Thin-film metallization stacks serve as reliable conductors on ceramic-based substrates for active implants”, IEEE Transactions on components, packing and manufacturing technology, vol. 10, no. 11 , November 2020, it can be seen that in the production of medical implants with electrical connection or contact structures, which are produced by means of conventional metal deposition processes, for example by sputtering, on a ceramic substrate, preferably in the form of an Al2O3 substrate, better results in terms of adhesion strength can be achieved than when using a screen printing process using metal paste followed by a high-temperature process.In particular, good results are achieved in the production of such electrical contact structures by metallizing with sputtered platinum on a tungsten-titanium bonding layer, which can increase the adhesion strength to the aluminum oxide substrate. The contact arrangement produced in this way is then encapsulated with biocompatible, electrically insulating material that protects the internal contact arrangement from the moist intracorporeal environment.

[0007] The document DE 10 2016222 710 A1 discloses an implantable electrical contact arrangement which has at least one electrode body arrangement otherwise completely made of biocompatible, electrically insulating material, with at least one freely accessible electrode surface which is directly or indirectly surrounded by the biocompatible, electrically insulating material.

[0008] Description of the invention

[0009] The invention is based on the object of developing an implantable electrical contact arrangement which has at least one electrode body arrangement made entirely of biocompatible, electrically insulating material, with at least one electrode surface directly or indirectly surrounded by the biocompatible, electrically insulating material, wherein the electrode body arrangement has a stack-shaped layer composite which has a metallization layer over an adhesion promoter layer at least on a ceramic substrate, in such a way that the resistance of the implantable electrical contact arrangement surrounded by the biocompatible, electrically insulating material to moisture or water from the intracorporeal moist environment is to be significantly improved in order to thereby extend the service life and the maximum intracorporeal operating time of the medical implant specified by the manufacturer.

[0010] The solution to the problem underlying the invention is specified in claim 1. Features that further develop the subject matter of the invention are the subject matter of the dependent claims and the further description, in particular with reference to the figures.

[0011] The implantable electrical contact arrangement according to the invention according to the features of the preamble of claim 1 is characterized in that the stacked layer composite of the electrode body arrangement is bonded to a passivation layer by forming covalent bonds and is otherwise completely encased by this layer, with the exception of at least one surface area of ​​the metallization layer facing away from the layer composite. Furthermore, the passivation layer has a passivation layer surface facing away from the stacked layer composite, to which the biocompatible, electrically insulating material directly or indirectly adjoins and, just as on the side of the layer composite, forms covalent bonds with the biocompatible, electrically insulating material.

[0012] Due to the covalent or chemical bonds that form between the surfaces of the stacked layer composite and the passivation layer, and preferably also between the passivation layer and the biocompatible electrically insulating material, which are based on the interaction of the outer electrons between atoms and / or molecules, the penetration of moisture or water is at least almost completely excluded, at least in the area of ​​the electrical contact arrangement encapsulated by the biocompatible, electrically insulating material.In this way, delaminations between the interfaces of two adjacent material layers, such as the interfaces within the stacked layer composite as well as the interfaces between the passivation layer and the stacked layer composite as well as between the passivation layer and the surrounding coating made of biocompatible, electrically insulating material, can be largely excluded.

[0013] Just as the adhesion promoter layer is deposited on the ceramic substrate and the metallization layer on the adhesion promoter layer is deposited, plasma-enhanced chemical vapor deposition (PECVD) is also suitable for depositing the passivation layer on the stacked layer composite and, if applicable, on existing surface areas of the ceramic substrate. Alternatively, physical vapor deposition (PVD) or a wet-chemical coating of the passivation layer on the stacked layer composite and, if applicable, adjacent surface areas of the ceramic substrate are also suitable.

[0014] The passivation layer is provided entirely on the surface of the stacked layer composite with the exception of at least that surface area of ​​the metallization layer which is intended for electrical contact with an electrical conductor structure, preferably in the form of an electrical cable, one cable end of which is permanently and firmly electrically contacted with the surface area of ​​the metallization layer intended for contact by means of a soldering, bonding or adhesive connection.

[0015] After establishing appropriate electrical contacts on the freely accessible surface areas of the metallization layer, the stacked layer assembly, which is otherwise completely coated with the passivation layer, including the ceramic substrate, is surrounded by the biocompatible, electrically insulating material. This material preferably consists of a polymer and, as such, is capable of seamlessly enclosing the stacked layer assembly including the ceramic substrate in a viscous state during a casting process before transitioning to a solid state through solidification. Particularly preferred polymers are the following types: silicones, polyimides, liquid crystal polymer (LCP), or parylene.

[0016] The encapsulation formed by the solidification of the solidified biocompatible, electrically insulating material also encloses the electrical conductor structures that are electrically contacted with the stacked layer composite.

[0017] The electrical conductor structure electrically connected to the at least one surface region of the metallization layer can in principle have any desired functions and shapes, for example it can represent an independent electrical component which is connected to the metallization layer via at least one electrical connection and which, with the exception of its electrical connections, is also coated with the passivation layer.

[0018] The stacked layer composite is preferably realized according to the construction method cited in the publication by Kiele et al. cited at the beginning, ie a titanium or tungsten-titanium layer is applied as an adhesion promoter layer on an aluminum oxide layer as a ceramic substrate, on which in turn a platinum or gold layer is applied in the form of the metallization layer.

[0019] In principle, one of the following compounds is suitable for the passivation layer: silicon oxide, silicon carbide, silicon nitride or silicon oxynitride.

[0020] Brief description of the invention

[0021] The invention is described below, without limiting the general inventive concept, using exemplary embodiments with reference to the drawings. They show:

[0022] Fig. 1 perspective top view of an implantable electrical

[0023] Contact arrangement and Fig. 2 Longitudinal section through an implantable electrical

[0024] Contact arrangement in the contact area with an electrical conductor structure.

[0025] Ways of implementing the invention, industrial applicability

[0026] Figure 1 shows a schematic perspective view of an implantable, electrical contact structure designed according to the solution, which serves for the electrical connection between electrical lines 1, which lead to a medically active implant (not shown), with electrical supply lines 2, which lead to an implantable supply unit (not shown), which provides electrical energy and control signals for operating the medical implant.

[0027] For the purpose of a 1:1 contact between the electrical lines 1 and the electrical supply and discharge lines 2, two, preferably identically designed electrical contact arrangements 3 are used, the layered structure of which is illustrated representatively and schematically in a sectional view in Figure 2.

[0028] On the one hand, the electrical contacts 11 serve to electrically contact the electrical lines 1 and the electrical contacts 12 serve to electrically contact the electrical supply and discharge lines 2. The individual electrical contacts 11 and 12 are each electrically connected to one another in pairs by means of a metallization layer in the form of a conductor track 13.

[0029] A bonding layer 5, preferably made of WTi or Ti, is deposited on a ceramic substrate 4, preferably made of Al2O3, by means of physical vapor deposition (PVD). A metallization layer 6, preferably in the form of platinum or gold, is deposited on the surface of the bonding layer using a PVD coating process. The deposition process for forming the metallization layer 6 is carried out using suitable pattern masks in order to enable extremely small-sized and geometrically limited layer deposits on the Al2O3 substrate 4.

[0030] Furthermore, a passivation layer 7 is also applied, using a PVD coating, both to the surface of the metallization layer 6 and to surrounding surface areas of the ceramic substrate 4. Silicon oxide is preferably suitable as the passivation layer 7, as it is capable of forming covalent bonds with both the metallization layer 6 and the ceramic layer 4. Only those surface areas of the metallization layer 6 remain uncoated with respect to the passivation layer 7 - where electrical contact is subsequently provided, each with a supply and discharge line 2 or with an electrical line 1.

[0031] In Figure 2, the surface area 8 of the metallization layer 6 intended for the electrical contacting of an electrical supply and discharge line 2 is not covered by the passivation layer 7. The end of the supply and discharge line 2 directly contacts the surface area 8 of the metallization layer 6 intended for the formation of the contact and is electrically and mechanically firmly connected to it by means of a soldering, bonding, or adhesive connection 9.

[0032] For a preferably complete enclosure or encapsulation of the implantable electrical contact arrangement 3, a biocompatible, electrically insulating material 10 is applied to the surface of the passivation layer 7, preferably by means of a casting process, and forms covalent bonds with it. In addition, the biocompatible, electrically conductive material 10 also encloses the electrical contact area 3 and, at least in the case of the electrical contacts 12, the electrical supply and discharge lines 2, which are mutually electrically insulated and also mechanically stably mounted by the biocompatible, electrically conductive material 10, similar to a matrix directly surrounding the electrical supply and discharge lines 2.The metallization layer 6 serves to create the electrical connection between the electrical contacts 11 and 12. It is formed between each contact point in the form of separate conductor tracks and locally connects the contact points 11, 12 in pairs. With the exception of the surface areas 8 of the metallization layer 6 intended for contacting the electrical cables 1 and the electrical supply and discharge lines 2, the passivation layer 7 is deposited over the entire surface of the top and bottom of the ceramic substrate 4 at the electrical contacts 11 and 12, as well as on the conductor tracks 13, in order to create a uniform surface for the formation of covalent bonds with the biocompatible and electrically insulating material layer 10 made of polymer material applied thereover.

[0033] List of reference symbols electrical line electrical supply and discharge lines electrical contact arrangement

[0034] Ceramic substrate

[0035] Adhesion promoter layer

[0036] Metallization layer

[0037] passivation layer

[0038] Surface area of ​​the metallization layer

[0039] Solder, bond or adhesive connection biocompatible, electrically conductive material electrical contact electrical contact

[0040] conductor track

Claims

Patent claims 1. An implantable electrical contact arrangement (3) comprising at least one electrode body arrangement made entirely of biocompatible, electrically insulating material (10), with at least one electrode surface directly or indirectly surrounded by the biocompatible, electrically insulating material (10), wherein the electrode body arrangement comprises a stacked layer composite having a metallization layer (6) at least on a ceramic substrate (4) above an adhesion promoter layer (5), characterized in that the stacked layer composite is bonded to a passivation layer (7) by forming covalent bonds and is otherwise completely encased by the latter, with the exception of at least one surface region (8) of the metallization layer (6) facing away from the layer composite, and in that the passivation layer (7) has a passivation layer surface facing away from the stacked layer composite,to which the biocompatible, electrically insulating material (10) is directly or indirectly adjacent, and that the passivation layer (7) is deposited on the stacked layer composite by means of plasma-enhanced chemical vapor deposition (PECVD), physical vapor deposition (PVD) or wet-chemical coating.

2. Contact arrangement according to claim 1, characterized in that the at least one surface area (8) of the metallization layer (6) not covered by the passivation layer (7) corresponds to the at least one electrode surface to which an electrical line (1) or an electrical supply and discharge line (2) is contacted.

3. Contact arrangement according to claim 1 or 2, characterized in that the metallization layer (6) is a Pt or gold layer.

4. Contact arrangement according to one of claims 1 to 3, characterized in that the adhesion promoter layer (5) is a WTi or titanium layer.

5. Contact arrangement according to one of claims 1 to 4, characterized in that the passivation layer (7) is a silicon oxide, silicon carbide, silicon nitride or silicon oxynitride layer 6. Contact arrangement according to one of claims 1 to 5, characterized in that the biocompatible, electrically insulating material (10) consists of a polymer.

7. Contact arrangement according to claim 6, characterized in that the polymer is one of the following polymers: silicone, polyimide, liquid crystal polymer (LCP), parylene.

8. Contact arrangement according to one of claims 1 to 7, characterized in that the biocompatible, electrically insulating material (10) is selected such that the biocompatible, electrically insulating material is connected at least to the passivation layer (7) via covalent bonds.

9. Contact arrangement according to one of claims 1 to 8, characterized in that an electrical component is connected to the metallization layer (6) via at least one electrical connection (129) which is coated with the exception of its electrical connection to the passivation layer (7).

10. Contact arrangement according to one of claims 1 to 9, characterized in that the stack-shaped layer composite is connected to a passivation layer (7) with the exclusive formation of covalent bonds.

11. Contact arrangement according to one of claims 1 to 10, characterized in that the passivation layer surface is connected to the biocompatible, electrically insulating material (10) exclusively by forming covalent bonds.

12. Contact arrangement according to one of claims 2 to 11, characterized in that the electrical contacting of the electrical line (1) or the electrical supply and discharge lines (2) is realized by means of a soldering, bonding or adhesive connection (9).

13. Contact arrangement according to one of claims 1 to 12, characterized in that the ceramic substrate (4) comprises an oxide ceramic.

14. Contact arrangement according to claim 13, characterized in that the oxide ceramic is Al2O3 or ZrO2.

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