WO2025008127A1

WO2025008127A1 - Novel feedthrough design

Info

Publication number: WO2025008127A1
Application number: PCT/EP2024/065446
Authority: WO
Inventors: Marcel Starke; Jan Romberg
Original assignee: Biotronik SE and Co KG
Current assignee: Biotronik SE and Co KG
Priority date: 2023-07-05
Filing date: 2024-06-05
Publication date: 2025-01-09
Anticipated expiration: 2026-01-05

Abstract

The present invention relates to an electrical feedthrough (2) for a medical device (1), comprising: a multi-layer structure (20) comprising a plurality of electrically insulating layers (21) and a plurality of conductive tracks (22), each conductive track (22) being arranged between two electrically insulating layers (21) of said plurality of electrically insulating layers (21), a plurality of first electrical contacts (23) arranged on a first end portion (25) of the multi-layer structure (20), and a plurality of second electrical contacts (24) arranged on an opposing second end portion (26) of the multi-layer structure (20), wherein each conductive track (22) connects a first electrical contact (23) to a second electrical contact (24), and a flange (4) comprising a top side (4a) and a bottom side (4b) facing away from the top side, wherein the flange (4) surrounds a through-hole (40) of the flange (4), the through-hole (40) extending from the top side (4a) to the bottom side (4b), and wherein the multi-layer-structure (20) extends through the through-hole (40) and is hermetically connected to the flange (4), such that the flange (4) extends around the multi-layer structure (20) and is arranged between the first end portion (25) and the second end portion (26).

Description

Novel feedthrough design

The present invention relates to an electrical feedthrough for a medical device and to a corresponding method for producing such a feedthrough.

In medical devices, particularly implantable medical devices such as cardiac pacemakers or cardioverter defibrillators, feedthroughs are used to contact electronic modules accommodated by a hermetically sealed casing of the respective medical device from the outside. By means of the feedthrough electrically conducting pins protrude out of the casing in a sealed fashion allowing, e.g., to electrically connect the pins to a connector or an antenna, e.g., in a header of the medical device that is connected to the casing.

In the prior art, electrical feedthroughs are based on compact ceramics as insulators into which pins are brazed by a brazing process. Furthermore, metallic antennas are usually designed as separate components that are manufactures, e.g., by stamping or etching.

Feedthroughs are currently produced as complex components having a special design. Particularly, the insulator is usually a complex body made of a compact ceramic. The feedthrough contacts are formed by wire sections (pins), which are soldered into the ceramic with pure gold solder using a high-temperature process. The ceramic itself is simultaneously soldered into a circumferential flange, again with pure gold solder. The flange usually consists of a turned or milled part. The manufacturing methods and technology limit the possible design, and the materials used must have a high temperature resistance. Because of the high process temperature, soldering must be carried out under vacuum or in a special inert gas atmosphere. On the other hand, antennas are usually stamped or etched in fine structures. These are easily deformable and mechanically unstable, wherein handling during assembly and further processing is complex. In addition, the antennas must be connected to the feedthrough pin mechanically and electrically by a joining process (e.g., welding or soldering).

Based on the above, the problem to be solved by the present invention is to provide an electrical feedthrough for a medical device having a simplified design, which particularly facilitates the integration of an antenna.

This problem is solved by an electrical feedthrough having the features of claim 1, a medical device having the features of claim 11, and a method having the features of claim 13. Appropriate embodiments of these aspects of the present invention are stated in the dependent claims and are described below.

According to claim 1, an electrical feedthrough for a medical device is disclosed, comprising: a multi-layer structure extending from a first end portion to an opposing second end portion along a first direction and comprising a plurality of electrically insulating layers and a plurality of conductive tracks, each conductive track being arranged between two electrically insulating layers of said plurality of electrically insulating layers, a plurality of first electrical contacts arranged on the first end portion of the multi-layer structure, and a plurality of second electrical contacts arranged on the second end portion of the multi-layer structure, wherein each conductive track connects a first electrical contact to a second electrical contact, a flange comprising a top side and a bottom side facing away from the top side, wherein the flange surrounds a through-hole of the flange, the through-hole extending from the top side to the bottom side, and wherein the multi-layer-structure extends through the through-hole and is hermetically connected to the flange, particularly such that the flange extends around the multi-layer structure and is arranged between the first end portion and the second end portion, and wherein, in particular, the flange is configured to be connected to a casing of the medical device, particularly such that the second electrical contacts are arranged outside the casing and the first electrical contacts are arranged in an internal space of the casing of the medical device.

Particularly, the multi-layer structure is substantially planar. Particularly, each conductive track extends at least partly along the first direction. Particularly, the first end portion extends or protrude into the internal space of the casing, and the second end portion extends to an outside of the casing or protrude out of the casing.

According to an embodiment, the electrical feedthrough according to the invention further comprises an antenna configured to receive and/or transmit an electromagnetic signal, the antenna comprising at least one conductive track arranged between two electrically insulating layers of the multi-layer structure, wherein particularly the antenna is arranged outside the casing.

According to an embodiment of the electrical feedthrough, the flange is connected to the multi-layer structure by a circumferential solder or braze joint so that the joint is hermetically sealed. Particularly, the solder or braze joint is arranged between an inside of the through- hole of the flange and a circumferential surface portion of a middle section of the multi-layer structure.

Furthermore, according to an embodiment of the present invention, the multi-layer structure is a flat planar multi-layer structure having a thickness normal to the electrically insulating layers in a first spatial direction, which thickness is smaller than the dimensions of the respective insulating layers in two spatial directions which are orthogonal to one another as well as orthogonal to the first spatial direction.

According to an embodiment of the present invention, the multi-layer structure is one of a multi-layer printed circuit board, a Low Temperature Cofired Ceramic (LTCC) multi-layer structure, a a high temperature cofired ceramics (HTCC) multi-layer structure, or a multilayer structure comprising one ore organic layers, e.g. made from a polyimide or an LCP (liquid crystal polymer), or a multi-layer structure manufactured by an additive manufacturing process.. Particularly, Low Temperature Co-fired Ceramic devices or structures are devices (or structures) where the entire ceramic support structure and any conductive, resistive, and dielectric materials are fired in a kiln at the same time at temperatures below 1000°C.

Furthermore, according to an embodiment of the present invention, the electrically insulating layers of the multi-layer structure are formed out of or comprise one of the following materials: a ceramic, a low temperature cofired ceramics (LTCC), a high temperature cofired ceramics (HTCC) or suitable organic multilayer substrates, e.g. made from an LCP (liquid crystal polymer), or a polyimide.

According to an embodiment, each first electrical contact is a contact pad configured for soldering, welding or gluing with a conductive adhesive an electrical conductor to it, or is formed by a connector. Likewise, according to a preferred embodiment each second electrical contact is a contact pad or is formed by a connector, particularly being configured for soldering, welding or gluing with a conductive adhesive. The respective connector may be plug connector, particularly configured receive a plug contact of an electrode lead.

Further, according to an embodiment of the present invention, the first electrical contacts are arranged on a first surface region of the first end portion of the multi-layer structure. In one embodiment, the first electrical contacts are arranged on a second surface region of the first portion, wherein the second surface region faces away from first surface region, i.e. the first surface region and the second surface region are on opposite sides of the first end portion. In one embodiment, the first electrical contacts are arranged on a first surface region of the first end portion and a second surface region of the first end portion facing away from the first surface region of the first end portion, particularly in an alternating manner, i.e. one first electrical contact is arranged on the first surface portion and the following second electrical contact is arranged on the second surface portion, respectively, or vice versa.

Furthermore, in a preferred embodiment, the second electrical contacts are arranged on a first surface region of the second end portion. In one embodiment, the second electrical contacts are arranged on a second surface region of the second portion, wherein the second surface region faces away from first surface region, i.e. the first surface region and the second surface region are on opposite sides of the second end portion. In one embodiment, the second electrical contacts are arranged on a first surface region of the second end portion and a second surface region of the second end portion facing away from the first surface region of the second end portion, particularly in an alternating manner, i.e. one second electrical contact is arranged on the first surface portion and the following second electrical contact is arranged on the second surface portion, respectively, or vice versa.

Particularly, the first surface region of the first end portion may faces away from the first surface region of the second end portion, i.e. are arranged on opposite sides of the multilayer-structure. Alternatively, the first surface region of the first end portion and the first surface portion of the second end portion may face in the same direction, i.e. are arranged on the same side of the multi-layer-structure.

According to yet another embodiment of the present invention, the antenna is connected to one of the first electrical contacts, so that in particular an electrical contact can be established between the antenna and an electronic circuit arranged in the internal space of a casing of the medical device. Particularly, the casing is formed out of a metal, preferably a biocompatible metal, such as titanium/ a titanium alloy, stainless steel or any other suitable metals/ alloys.

Furthermore, according to an embodiment of the present invention, the antenna comprises a loop or a meandering portion.

Further, particularly in order to provide a stress relief within the flange of the electrical feedthrough, the through-hole of the flange comprises four rounded corner regions. Alternatively, or in addition, the flange comprises spacers protruding from an inside of the through-hole of the flange. Said rounded corner regions can correspond to a portion of a cylinder mantle, respectively. According to yet another aspect of the present invention, a medical device comprising a casing and an electrical feedthrough according to the present invention is disclosed, wherein the flange is connected (particularly welded) to the casing, such the second electrical contacts, and optionally the antenna, are arranged outside the casing and such that the first contacts are arranged in an internal space of the casing. Preferably, the casing is formed out of a metal, particularly a biocompatible metal such as titanium, titanium alloy, stainless steel or any other suitable metals/ alloys. Particularly,

According to an embodiment, the medical device comprises a header, particularly having an outer surface formed out of a biocompatible plastic material, wherein the header is connected to the casing, and wherein the antenna and the second electrical contacts are integrated into the header.

According to an embodiment, the medical device is an implantable medical device, particularly a cardiac pacemaker or a cardioverter defibrillator. Other implantable medical devices are also conceivable.

Furthermore, according to a further aspect of the present invention, a method for producing an electrical feedthrough for a medical device is disclosed, comprising the steps of:

- providing a multi-layer structure comprising a plurality of electrically insulating layers and a plurality of conductive tracks, each conductive track being arranged between two electrically insulating layers of said plurality of electrically insulating layers, , and wherein a plurality of first electrical contacts is arranged on a first end portion of the multi-layer structure, and a plurality of second electrical contacts is arranged on an opposing second end portion of the multi-layer structure, wherein each conductive track connects a first electrical contact to a second electrical contact,

- providing a flange comprising a top side and a bottom side facing away from the top side, wherein the flange surrounds a through-hole of the flange, the through-hole extending from the top side to the bottom side,

- inserting the multi-layer structure into the through-hole of the flange and hermetically joining, particularly soldering, the multi-layer structure to the flange, particularly such that the flange extends around the multi-layer structure and is arranged between the first end portion and the second end portion.

According to an embodiment of the method according to the invention, the multi-layer structure further comprises an antenna for receiving an electromagnetic signal, the antenna comprising at least one conductive track arranged between two electrically insulating layers of the multi-layer structure.

According to an embodiment of the method according to the invention, the flange is joined (particularly welded) to a casing of a medical device such that the antenna and the second electrical contacts are arranged outside the casing and the first contacts are arranged in an internal space of the casing, wherein particularly the antenna and the second electrical contacts are enclosed in a header connected to the casing. Particularly, the header comprises an outer surface formed out of a biocompatible plastic material, e.g. an epoxy resin.

According to an embodiment of the method according to the invention, the multi-layer structure is formed by a Low Temperature Cofired Ceramics (LTCC) process. Furthermore, according to yet another preferred embodiment, the flange is formed by metal injection molding (MIM). Alternatively, other manufacturing processes are applicable to form the flange, such as forming processes, machining processes, additive processes.

In the following, embodiments of the present invention, as well as further features and advantages of the present invention shall be described with reference to the Figures, wherein

Fig. 1 shows a top view onto an embodiment of an electrical feedthrough according to the present invention;

Fig. 2 shows a cross-sectional view of anther embodiment,

Fig. 3 shows a top view onto a further embodiment of an electrical feedthrough according to the present invention; Fig. 4 shows a cross-sectional view of the embodiment shown in Fig. 3,

Fig. 5 shows a top view onto a flange of an embodiment of the electrical feedthrough according to the present invention,

Fig. 6 shows a modification of the flange shown in Fig. 5, the flange further comprising recesses for stress relief,

Fig. 7 shows a top view onto an antenna of the embodiment of the electrical feedthrough according to the present invention shown in Fig. 1,

Fig. 8 shows a top view onto an antenna of the embodiment of the electrical feedthrough according to the present invention shown in Fig. 3, and

Fig. 9 shows a schematic illustration of a medical device, here in form of an implantable cardiac pacemaker, comprising an electrical feedthrough according to the present invention.

Fig. 1 shows an embodiment of an electrical feedthrough 2 according to the present invention. The feedthrough 2 comprises a multi-layer structure 20 comprising a plurality of electrically insulating layers 21 stacked on top of one another and a plurality of conductive tracks 22, each conductive track 22 being arranged between two electrically insulating layers 21 of said plurality of electrically insulating layers 21. Preferably, the multi-layer structure 20 is a flat planar structure, i.e., comprises a thickness T in a first spatial direction x that is significantly smaller than the dimensions of the structure 20 in directions orthogonal to the first spatial direction x. The feedthrough 2 further comprises a plurality of first electrical contacts 23 arranged on a first end portion 25 of the multi-layer structure 20, and a plurality of second electrical contacts 24 arranged on an opposing second end portion 26 of the multilayer structure 20, wherein each conductive track 22 connects a first electrical contact 23 to a second electrical contact 24 as shown e.g. in Fig. 2. The feedthrough 2 further comprises an integrated antenna 3 that is also depicted in a top view in Fig. 7. The antenna 3 is configured to receive and/or transmit an electromagnetic signal and is comprised of at least one conductive track 30 that may have a portion comprising a meandering shape as indicated in Figs. 1 and 7. The antenna 3 can be arranged between two electrically insulating layers 21 of the multi-layer structure 20. Furthermore, the feedthrough 2 comprises a metallic flange 4 for connecting the feedthrough 2 to a casing 5 of a medical device 1 (cf. Fig. 9). As indicated in Figs. 1 and 2, the flange 4 comprises a top side 4a that may have a circumferential step so as to be able to receive an edge region of the casing 5 such that the edge region is flush with an outer surface of the casing 5 when the latter is connected to the flange (cf. e.g. Fig. 9). Furthermore, the flange 4 comprises a bottom side 4b facing away from the top side 4a, wherein the flange 4 surrounds a through-hole 40 of the flange 4, wherein the through-hole 40 extends from the top side 4a to the bottom side 4b. The multilayer-structure 20 is inserted into this through-hole 40 and is hermetically connected to a circumferential surface portion of the flange 4, particularly via a solder or braze joint 43, such that the flange 4 is arranged between the first end portion 25 and the second end portion 26. Due to this position of the flange 4, the antenna 3 and the second electrical contacts 24 are arranged outside the casing 5 and the first electrical contacts 23 are arranged in an internal space 50 of the casing 5 (c.f. e.g. Fig. 9). Particularly, the first electrical contacts 23 can be arranged on a surface region 25a of the first end portion 25 of the multi-layer structure 20, whereas the second electrical contacts 24 are arranged on a surface region 26a of the second end portion 26. As indicated in Fig. 2, the surface region 25a of the first end portion 25 faces away from the surface region 26a of the second end portion 26. However, the first and second contacts 23, 24 may also be arranged on the same side of the multi-layer structure 20.

Figs. 3 and 4 show a modification of the embodiment shown in Figs. 1 and 2, wherein in contrast to Figs. 1 and 2, the antenna 3 forms a loop 3 as shown in Figs. 4 and 8, wherein the antenna 3 comprises a gap 32 and a slot 33 within the antenna 3 defined by the open loop 31 of the antenna 3. Particularly, in both embodiments, antenna functions may be structured in one or more layers of the multi-layer structure 20.

Furthermore, in both embodiments shown in Figs. 1 to 4, the contacts 23, 24 are designed in such a way that contacting can be ensured via corresponding connectors, or, alternatively, by desired joining processes, such as soldering, brazing or welding, alternatively using a conductive glue. Figs. 5 and 6 depict embodiments for the welding flange 4 that may be used in conjunction with the electrical feedthrough 2 as e.g. shown in Figs. 1 to 4. The flange 4 is preferably produced in a primary forming process, e.g. with metal injection molding (MIM) technology. Alternatively, other manufacturing processes are applicable, such as forming processes, machining processes, additive processes. The flange 4 is shaped to accommodate the multilayer structure 20 and therefore comprises in the case of flat structures 20, for example, an elongated rectangular through-opening 40. The inside 40a of the through-hole 40 can comprise rounded corner regions 42. Additionally, the flange 4 can comprise spacers 41 protruding from an inside 40a of the flange 4 to center the multi-layer structure 20 and to adjust tensions due to the solder thickness.

Particularly, the multi-layer structure 20 may be manufactured by means of a low temperature cofired ceramics (LTCC) technology. The flange 4 and the multi-layer structure are preferably coated in the necessary areas for soldering, depending on the solder used.

The electrical feedthrough 2 according to the present invention is particularly suited for medical devices 1, particularly implantable medical devices such as implantable cardiac pacemakers or cardioverter-defibrillators. An embodiment of such a device is shown in Fig. 9. Here, the implantable medical device 1 comprises a casing 5, particularly out of a biocompatible material such as a titanium alloy, and an electrical feedthrough 1 according to the present invention (cf. e.g. Figs. 1 to 4), wherein the flange 4 is connected, particularly welded, to the casing 5 such that the antenna 3 and the second electrical contacts 24 are arranged outside the casing 5 and the first contacts 23 are arranged in an internal space 50 of the casing 5. Particularly, the antenna 3 and the second electrical contacts 24 are integrated into a header 6 that is connected to the casing 5.

Advantageously, the present invention allows to use a low process temperature to solder the multi-layer structure to the flange to create a feedthrough, particularly without needing a vacuum, e.g. in a process utilizing a one-piece flow instead of a batch process. Since connections such as electrical vias and the antenna can be integrated into the multi-layer structure, they do not need to be provided as separate components rendering the feedthrough and the corresponding production method more cost effective.

Claims

1. An electrical feedthrough (2) for a medical device (1), comprising: a multi-layer structure (20) extending from a first end portion (25) to an opposing second end portion (26) along a first direction and comprising a plurality of electrically insulating layers (21) and a plurality of conductive tracks (22), each conductive track (22) being arranged between two electrically insulating layers (21) of said plurality of electrically insulating layers (21), a plurality of first electrical contacts (23) arranged on the first end portion (25) of the multi-layer structure (20), and a plurality of second electrical contacts (24) arranged on the end portion (26) of the multi-layer structure (20), wherein each conductive track (22) connects a first electrical contact (23) to a second electrical contact (24), a flange (4) comprising a top side (4a) and a bottom side (4b) facing away from the top side, wherein the flange (4) surrounds a through-hole (40) of the flange (4), the through-hole (40) extending from the top side (4a) to the bottom side (4b), and wherein the multi-layer-structure (20) extends through the through-hole (40) and is hermetically connected to the flange (4), such that the flange (4) extends around the multi-layer structure (20) and is arranged between the first end portion (25) and the second end portion (26), and wherein the flange (4) is configured to be connected to a casing (5) of the medical device (1).

2. The electrical feedthrough according to claim 1, further comprising an antenna (3) for receiving an electromagnetic signal, the antenna (3) comprising at least one conductive track (30) arranged between two electrically insulating layers (21) of the multi-layer structure (20).

3. The electrical feedthrough according to claim 1 or 2, wherein the flange (4) is connected to the multi-layer structure (20) by a circumferential joint (43), particularly a solder or brazing joint (43), welding joint or glue joint.

4. The electrical feedthrough according to one of the preceding claims, wherein the multilayer structure (20) is a flat planar multi-layer structure, particularly a multi-layer printed circuit board.

5. The electrical feedthrough according to one of the preceding claims, wherein the electrically insulating layers (21) are formed out of or comprise one of the following materials: a ceramic, a low temperature cofired ceramics (LTCC), high temperature cofire ceramics (HTCC) or organic multilayer structures, e.g. comprising an LCP or a polyimide.

6. The electrical feedthrough according to one of the preceding claims wherein each first electrical contact (23) is a contact pad or is formed by a connector, and/or wherein each second electrical contact (24) is a contact pad or is formed by a connector.

7. The electrical feedthrough according to one of the preceding claims, wherein

- the first electrical contacts (23) are arranged on a first surface region (25a) of the first end portion (25) of the multi-layer structure (20) and/or on a second surface region (25a) of the first end portion (25) facing away from the first surface region (25a) of the first end portion (25), and

- the second electrical contacts (24) are arranged on a first surface region (26a) of the second end portion (26) and/or on a second surface region (26b) of the second end portion (26) facing away from the first surface region (26a) of the second end portion (26) , wherein particularly

- the first surface region (25a) of the first end portion (25) faces away from the first surface region (26a) of the second end portion (26), or

- the surface region (25a) of the first end portion (25) and the first surface portion (26a) of the second end portion (26) face in the same direction.

8. The electrical feedthrough according to one of the preceding claims, wherein the antenna (3) is connected to one of the first electrical contacts (23).

9. The electrical feedthrough according to one of the preceding claims, wherein the antenna (3) comprises an open loop (31) or a meandering portion (30).

10. The electrical feedthrough according to one of the preceding claims, wherein the through-hole (40) of the flange (4) comprises four corner regions (41), each corner region (41) comprising a recess (42) for stress relief.

11. A medical device comprising a casing (5) and an electrical feedthrough (1) according to one of the preceding claims, wherein the flange (4) is connected to the casing (5) such that the second electrical contacts (24), and optionally the antenna (3), are arranged outside the casing (5) and the first contacts (23) are arranged in an internal space (50) of the casing (5).

12. The medical device according to claim 11, wherein the medical device (1) comprises a header (6) connected to the casing (5), wherein the antenna (3) and the second electrical contacts (24) are enclosed by the header (6).

13. A method for producing an electrical feedthrough (2) for a medical device (1), comprising the steps of:

Providing a multi-layer structure (20) comprising a plurality of electrically insulating layers (21) and a plurality of conductive tracks (22), each conductive track (22) being arranged between two electrically insulating layers (21) of said plurality of electrically insulating layers (21), wherein the multi-layer structure (20) further comprises an antenna (3) for receiving an electromagnetic signal, the antenna (3) comprising at least one conductive track (22) arranged between two electrically insulating layers (21) of the multi-layer structure (20), and wherein a plurality of first electrical contacts (23) is arranged on a first end portion (25) of the multi-layer structure (20), and a plurality of second electrical contacts (24) is arranged on an opposing second end portion (26) of the multi-layer structure, wherein each conductive track (22) connects a first electrical contact (23) to a second electrical contact (24), Providing a flange (4) comprising a top side (4a) and a bottom side (4b) facing away from the top side (4a), wherein the flange (4) surrounds a through-hole (40) of the flange (4), the through-hole (40) extending from the top side (4a) to the bottom side (4b), and - Inserting the multi-layer structure (20) into the through-hole (40) of the flange (4) and hermetically joining the multi-layer structure (20) to the flange (4).

14. The method according to claim 13, wherein the multi-layer structure (20) is formed by an LTCC process, HTCC or organic multilayer structure, e.g. made from an LCP or a polyimide.

15. The method according to claim 13 or 14, wherein the flange (4) is formed by molding, particularly metal injection molding (MIM), machining, milling, or an additive manufacturing method, particularly 3D-printing.