Abstract:
A multilayered feedthrough for an implantable medical device includes a substrate having a first edge, a second edge, and a substrate length. A plurality of traces is formed on the substrate and extends along the substrate length. The plurality of traces extends to the first and second edges of the substrate. An insulator layer is formed on the substrate and the plurality of traces. A ground plane layer is formed on the insulator layer.

Description:
FIELD 
       [0001]    The present disclosure relates to electrical interconnects for implantable medical systems and devices, and, more particularly, to a co-fired ceramic electrical feedthrough assembly. 
       INTRODUCTION 
       [0002]    The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
         [0003]    Miniaturized electrical feedthroughs are required for implantable medical devices (IMDs) that offer reduced functional volume in a small package while offering a high level of electromagnetic interference (EMI) protection. In conventional feedthrough technologies, EMI filtering is oftentimes accomplished by mounting chip-type capacitors or discoidal capacitors on the surface of an electrical feedthrough. This technology suffers from the disadvantage of increasing overall device volume while increasing lead interconnect length required to attach the termination of the capacitor to the hermetic pin assembly and grounding structure (typically the ferrule and a portion of the outer enclosure of a metallic IMD). Technologies are required that enable integration of EMI protection while improving the electrical performance in a very small, low-profile, miniaturized device structure. 
         [0004]    The present teachings provide a feedthrough assembly of the type used, for example, in implantable medical devices such as heart pacemakers and the like, wherein the feedthrough assembly is constructed of a plurality of layers of a non-conductive material with conductive traces present thereon. 
       SUMMARY 
       [0005]    In various exemplary embodiments, the present disclosure relates to a multilayered feedthrough for an implantable medical device. The multilayered feedthrough includes a first edge and a second edge, and further includes a substrate having a first edge, a second edge, and a substrate length. A plurality of traces is formed on the substrate and extends along the substrate length. A plurality of contact pads is electrically coupled with the plurality of traces and extends to the first and second edges of the substrate. An insulator layer is formed on the substrate and the plurality of traces. The feedthrough further includes a ground plane layer. 
         [0006]    In various exemplary embodiments, the present disclosure relates to a multilayered feedthrough for an implantable medical device. The multilayered feedthrough includes a substrate having a first edge, a second edge, a substrate length, a first surface and a second surface opposite the first surface. A first plurality of traces is formed on the first surface and extends along the substrate length. A second plurality of traces is formed on the second surface and extends along the substrate length. A first plurality of contact pads is electrically coupled with the first plurality of traces and extends to the first and second edges of the substrate. A second plurality of contact pads is electrically coupled with the second plurality of traces and extends to the first and second edges of the substrate. A first insulator layer is formed on the first surface and the first plurality of traces. A second insulator layer is formed on the second surface and the second plurality of traces. The feedthrough further includes first and second ground plane layers. 
         [0007]    Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0008]    The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein: 
           [0009]      FIGS. 1 and 2  are isometric and exploded views, respectively, of a feedthrough assembly according to various embodiments of the present disclosure; 
           [0010]      FIG. 3  is an isometric view of a feedthrough assembly according to various embodiments of the present disclosure; 
           [0011]      FIG. 4  is an isometric view of a feedthrough assembly with an integrated transceiver according to various embodiments of the present disclosure; 
           [0012]      FIG. 5  is an isometric view of a feedthrough assembly with attached weld ring according to various embodiments of the present disclosure; 
           [0013]      FIG. 6  is an isometric view of a feedthrough assembly according to various embodiments of the present disclosure; and 
           [0014]      FIG. 7  is a cross-sectional view of the feedthrough assembly of  FIG. 6  along line  7 - 7 . 
       
    
    
     DESCRIPTION 
       [0015]    The following description is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses. For purposes of clarity, the same reference numbers will be used in the drawings to identify similar elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A or B or C), using a non-exclusive logical or. It should be understood that steps within a method can be executed in different order without altering the principles of the present disclosure. 
         [0016]    Referring now to  FIGS. 1 and 2 , a feedthrough assembly  10  according to various embodiments of the present disclosure as illustrated. The feedthrough assembly  10  includes a plurality of layers. A substrate  14  includes a plurality of traces  15  formed on one or both sides of the substrate  14 . The substrate  14  can be made of any non-conductive material, for example, a high temperature co-fired ceramic or other ceramic material. The traces  15  can be formed on the substrate  14  by depositing a conductive material, such as platinum, gold or palladium, on the surface of substrate  14  such that they extend from one edge of the substrate to the other. Other methods of forming traces  15  can be utilized. 
         [0017]    The traces  15  can be formed on a first surface  144   a  and/or a second surface  144   b  of the substrate  14 . In various embodiments, integrated devices such as capacitors and/or filtering devices, e.g., SAW filters, can be formed (for example, by screening or photo lithography processes) on the substrate  14  or applied to the substrate  14 , and electrically connected to the traces  15 /contact pads  150 . For example, a SAW filter can be made from various materials, such as lithium niobate or lithium tantalate, and surface mounted to the substrate  14 . In this case, the insulator layer(s), which are described below, can encase the SAW filter to serve as a hermetic housing. 
         [0018]    An insulator layer  13   a ,  13   b  can be formed on the first and second surfaces  144   a ,  144   b , respectively. The insulator layer can be formed of any non-conductive material, such as a high temperature co-fired ceramic or other ceramic material, similar to the substrate  14 . In some embodiments, the insulator layers  13   a ,  13   b  can be formed of any biostable and biocompatible materials, e.g., alumina, zirconia or a combination thereof. In various embodiments, the insulator layer  13   a ,  13   b  covers only a portion of the first and second surfaces  144   a ,  144   b  of the substrate  14 . For example, substrate edges  142   a ,  142   b  can remain exposed and not covered by insulator layer  13   a ,  13   b . In this manner, traces  15  can be electrically connected to the IMD. 
         [0019]    Ground planes  12   a ,  12   b  can be formed on the insulator layer  13   a ,  13   b  in various embodiments. The ground planes  12   a ,  12   b  can be formed of any conductive material, such as platinum, gold, palladium or other metal. The ground planes  12   a ,  12   b  assist in shielding the traces  15  from stray electromagnetic interference, as well as minimizing interference between the traces  15  themselves. In various embodiments, the ground planes  12   a ,  12   b  can be formed of a continuous layer of conductive material covering the insulator layers  13   a ,  13   b . In some embodiments, the ground planes  12   a ,  12   b  can be formed of a mesh or grid of conductive material covering the insulator layers  13   a ,  13   b . Another insulator layer  11   a ,  11   b  can be formed on the ground planes  12   a ,  12   b  to insulate the ground planes  12   a ,  12   b  from the IMD. 
         [0020]    While the illustrated embodiments show the ground planes  12   a ,  12   b  to be formed on layers separate from substrate  14 , the present disclosure encompasses the formation of ground planes  12   a ,  12   b  in different configurations. For example, ground planes  12   a ,  12   b  can be formed on the substrate  14  and electrically insulated from traces  15 . Furthermore, ground planes  12   a ,  12   b  can be formed to substantially surround the substrate  14  and/or be oriented perpendicular to the first and second surfaces  144   a ,  144   b  of substrate  14 . Ground planes  12   a ,  12   b  can be connected to electrical ground potential in various ways, for example, by connection with one or more of the traces  15 , one or more of the contact pads  150 , with a weld ring  35  (described more fully below) or a combination thereof. For example only, ground planes  12   a ,  12   b  can be connected with traces  15  through the use of one or more vias formed in an insulator layers or layers  11   a ,  11   b . The use of vias is described more fully below with respect to  FIGS. 6-7 . 
         [0021]    The traces  15  of the feedthrough assembly  10  can extend to the edges  142   a ,  142   b  of the substrate  14 . In this manner, the traces  15  can be utilized as card edge connectors to mate with corresponding receiver slots (not shown) present, e.g., in the IMD. In various embodiments, contact pads  150  are included as part of the traces  15 . The contact pads  150  can have a larger surface area than traces  15  such that positive coupling between the traces and the associated circuitry of the IMD can be assured. In various embodiments, the traces  15 /contact pads  150  can extend around the edges  142   a ,  142   b  and be present on end surfaces  140  of the substrate  14 , as shown in  FIG. 3 . The presence of the traces  15 , with or without contact pads  150 , on the end surfaces  140  can provide a more consistent coupling between the feedthrough assembly  10  and the receiver slots of the IMD. 
         [0022]    Referring now to  FIG. 4 , a feedthrough assembly  20  with an integrated transceiver  26  according to various embodiments of the present disclosure as illustrated. Similar to feedthrough assembly  10  discussed above, the feedthrough assembly  20  includes a plurality of layers. A substrate  24  includes a plurality of traces  25  formed on one or both sides of the substrate  24 . The substrate  24  can be made of any non-conductive material, for example, a high temperature co-fired ceramic or other ceramic material. The traces  25  can be formed on the substrate  24  by depositing a conductive material, such as platinum, gold or palladium, on the surface of substrate  24  such that they extend from one edge of the substrate to the other. Other methods of forming traces  25  can be utilized. The traces  25  can be formed on a first surface  244   a  and/or a second surface  244   b  of the substrate  14 . The traces  25  can include contact pads, similar to that described above in regard to traces  15  and contact pads  150 . In various embodiments, integrated devices such as capacitors and/or filtering devices, e.g., SAW filters, can be formed on the substrate  24  and electrically connected to the traces  25 . 
         [0023]    An insulator layer  23   a ,  23   b  can be formed on the first and second surfaces  244   a ,  244   b , respectively. The insulator layer can be formed of any non-conductive material, such as, a high temperature co-fired ceramic or other ceramic material, similar to the substrate  24 . In various embodiments, the insulator layer  23   a ,  23   b  covers only a portion of the first and second surfaces  244   a ,  244   b  of the substrate  24 . Substrate edges  242   a ,  242   b  can remain exposed and not covered by insulator layer  23   a ,  23   b . In this manner, traces  25  can be electrically connected to the IMD. 
         [0024]    Ground planes  22   a ,  22   b  can be formed on the insulator layer  23   a ,  23   b  in various embodiments. The ground planes  22   a ,  22   b  can be formed of any conductive material, such as platinum, gold, palladium or other metal. The ground planes  22   a ,  22   b  assist in shielding the traces  25  from stray electromagnetic interference, as well as minimizing interference between the traces  25  themselves. In various embodiments, the ground planes  22   a ,  22   b  can be formed of a continuous layer of conductive material covering the insulator layers  23   a ,  23   b . In some embodiments, another insulator layer  21   a ,  21   b  is formed on the ground planes  22   a ,  22   b  to insulate the ground planes  22   a ,  22   b  from the IMD. As described above, ground planes  22   a ,  22   b  can be connected to electrical ground potential in various ways, for example, by connection with one or more of the traces  25 , one or more of the contact pads  150 , with a weld ring  35  (described more fully below) or a combination thereof. 
         [0025]    The traces  25  of the feedthrough assembly  20  can extend to the edges  242   a ,  242   b  of the substrate  24 . In this manner, the traces  25  can be utilized as card edge connectors to mate with corresponding receiver slots (not shown) present, e.g., in the IMD. In various embodiments, the traces  25  can extend to around the edges  242   a ,  242   b  and be present on end surfaces  240  of the substrate  24 , as shown in  FIG. 3  with respect to feedthrough assembly  10 . The presence of the traces  25  on the end surfaces  240  can provide a more consistent coupling between the feedthrough assembly  20  and the receiver slots of the IMD. 
         [0026]    An integrated transceiver  26  can be surface mounted on the substrate  24 , as illustrated in  FIG. 4 . A signal-in trace  262  can be electrically connected to integrated transceiver  26  from the IMD. In this manner, integrated transceiver  26  can receive signals from the IMD. Integrated transceiver  26  can be further electrically connected to a signal-out trace  264 . Signal-out trace  264  can be electrically connected to an antenna or transmission/reception element (not shown). In this manner, integrated transceiver  26  can transmit information received from the IMD to, as well as receive information from, a remote device. Integrated transceiver  26  can be powered by power lines  266  formed as traces on substrate  24 . In various embodiments, transceiver  26  can include power lines and/or include signal-in and signal-out lines that are separate from the substrate  24  and traces  25  formed thereon, such as with a wire or ribbon bond. 
         [0027]    Referring now to  FIG. 5 , a feedthrough assembly  30  according to various embodiments of the present disclosure as illustrated. Feedthrough assembly  30  can be substantially similar to feedthrough assemblies  10  and  20  described above. Weld ring  35  can be hermetically sealed to feedthrough assembly  30 . Weld ring  35  can be can be made of any biostable and biocompatible material, for example, titanium, niobium, tantalum or combinations thereof. Weld ring  35  can also be connected to the body of IMD such that there is a hermetic seal between IMD and feedthrough assembly  30 . The weld ring  35  can be coupled to the feedthrough assembly in various manners, such as by braze joint, diffusion bond, glass seal or a compression seal. 
         [0028]    Referring now to  FIGS. 6 and 7 , a feedthrough assembly  200  according to various embodiments of the present disclosure as illustrated. The feedthrough assembly  200  includes a plurality of layers. A substrate  204  includes a plurality of traces  205  ( FIG. 7 ) formed on one or both sides of the substrate  204 . The substrate  204  can be made of any non-conductive material, for example, a high temperature co-fired ceramic or other ceramic material. The traces  205  can be formed on the substrate  204  by depositing a conductive material, such as platinum, gold or palladium, on the surface of substrate  204 . Other methods of forming traces  205  can be utilized. 
         [0029]    The traces  205  can be formed on a first surface  244   a  and/or a second surface  244   b  of the substrate  204 . In various embodiments, integrated devices such as capacitors and/or filtering devices, e.g., SAW filters, can be formed (for example, by screening or photo lithography processes) on the substrate  204  or applied to the substrate  204 , and electrically connected to the traces  205 /contact pads  250 . For example, a SAW filter can be made from various materials, such as lithium niobate or lithium tantalate, and surface mounted to the substrate  204 . In this case, the insulator layer(s), which are described below, can encase the SAW filter to serve as a hermetic housing. 
         [0030]    An insulator layer  203   a ,  203   b  can be formed on the first and second surfaces  244   a ,  244   b , respectively. The insulator layer can be formed of any non-conductive material, such as a high temperature co-fired ceramic or other ceramic material, similar to the substrate  204 . In some embodiments, the insulator layers  203   a ,  203   b  can be formed of any biostable and biocompatible materials, e.g., alumina, zirconia or a combination thereof. In various embodiments, the insulator layer  203   a ,  203   b  covers the entire first and second surfaces  244   a ,  244   b  of the substrate  204 . 
         [0031]    Ground planes  202   a ,  202   b  can be formed on the insulator layer  203   a ,  203   b  in various embodiments. The ground planes  202   a ,  202   b  can be formed of any conductive material, such as platinum, gold, palladium or other metal. The ground planes  202   a ,  202   b  assist in shielding the traces  205  from stray electromagnetic interference, as well as minimizing interference between the traces  205  themselves. In various embodiments, the ground planes  202   a ,  202   b  can be formed of a continuous layer of conductive material covering the insulator layers  203   a ,  203   b . In some embodiments, the ground planes  202   a ,  202   b  can be formed of a mesh or grid of conductive material covering the insulator layers  203   a ,  203   b . Another insulator layer  201   a ,  201   b  can be formed on the ground planes  202   a ,  202   b  to insulate the ground planes  202   a ,  202   b  from the IMD. While the illustrated embodiments show the ground planes  202   a ,  202   b  to be formed on layers separate from substrate  204 , the present disclosure encompasses the formation of ground planes  202   a ,  202   b  in different configurations. For example, ground planes  202   a ,  202   b  can be formed on the substrate  204  and electrically insulated from traces  205 . Furthermore, ground planes  202   a ,  202   b  can be formed to substantially surround the substrate  204  and/or be oriented perpendicular to the first and second surfaces  244   a ,  244   b  of substrate  204 . As described above, ground planes  202   a ,  202   b  can be connected to electrical ground potential in various ways, for example, by connection with one or more traces  205 , one or more contact pads  250 , a weld ring  35  (described more fully below) or a combination thereof. 
         [0032]    In various embodiments, the traces  205  of the feedthrough assembly  200  do not extend to the edges of the substrate  204 . Instead, contact pads  250  are formed on a separate layer (in the illustrated example, insulator layer  201   a ) and electrically coupled with traces  205 . In this manner, the contact pads  250  can be utilized as card edge connectors to mate with corresponding receiver slots (not shown) present, e.g., in the IMD. The contact pads  250  can have a larger surface area than traces  205  such that positive coupling between the traces and the associated circuitry of the IMD can be assured. In various embodiments, the contact pads  250  can extend around the edges of the feedthrough assembly, similar to feedthrough assembly  20  illustrated in  FIG. 3 . The presence of the contact pads  250  on the end surfaces can provide a more consistent coupling between the feedthrough assembly  200  and the receiver slots of the IMD. 
         [0033]    The traces  205  can be electrically coupled with the contact pads  250  by vias  255 . Vias  255  extend between the various layers of feedthrough assembly  200 , and can be formed of any conductive material, such as platinum, gold, palladium or other metal. In the illustrated embodiment, vias  255  extend through insulator layer  201   a , ground plane  202   a  and insulator layer  203   a  to couple contact pads  250  to traces  205 . In order to isolate the vias  255  from ground plane  202   a , apertures  257  are formed in ground plane  202   a  through which vias  255  extend. In some embodiments, apertures  257  can be filled with an insulative material. In other various embodiments, apertures  257  can be hollow openings in the various layers through which vias  255  extend. 
         [0034]    In various embodiments of the present disclosure, feedthrough assembly  200  can include a weld ring  235  to hermetically seal feedthrough assembly  200 . Weld ring  235  can also be connected to the body of IMD such that there is a hermetic seal between IMD and feedthrough assembly  200 . The weld ring  235  can be coupled to the feedthrough assembly in various manners, such as by braze joint, diffusion bond, glass seal or a compression seal. Furthermore, in various embodiments, feedthrough assembly  200  can include an integrated transceiver, similar to feedthrough assembly  20  described above and illustrated in  FIG. 4 . 
         [0035]    The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims.