Abstract:
A ferrule for an implantable medical device (IMD) can employ stamped metal portion including an electrically-conductive ferrule portion. The stamped ferrule portion can be affixed to a wall of a housing of the IMD. The resulting ferrule can provide cost savings or higher production throughput over a ferrule employing machined ferrule portion.

Description:
CLAIM OF PRIORITY 
       [0001]    This application is a continuation of U.S. application Ser. No. 13/765,350, filed Feb. 12, 2013, which claims the benefit of priority under 35 USC 119(e) to U.S. Provisional Application No. 61/598,961, filed on Feb. 15, 2012, entitled, “CAPACITIVE FILTER FERRULE FOR IMPLANTABLE MEDICAL DEVICE,” and U.S. Provisional Application No. 61/682,466, filed on Aug. 13, 2012, entitled “FERRULE FOR IMPLANTABLE MEDICAL DEVICE,” each of which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    An electrical feedthrough can be used in an implantable medical device (IMD) to provide an isolated electrical circuit path from the exterior of the IMD to an interior of a housing. Feedthroughs can be used with housings that are sealed, such as a biocompatible hermetically sealed housing. The electrical path can provide an electrical connection to components inside the housing from outside the housing. To preserve internal components, the feedthrough can be leak-resistant. Some feedthrough designs are biocompatible and hermetically sealed. Some implantable medical devices using such a hermetically sealed housing can protect implanted electronics from body fluids and can resist undesirable exposure of the patient to materials from inside the housing. 
         [0003]    To provide such a feedthrough, a ferrule, or mechanical element can be disposed through the housing and coupled to the housing. An electrical conductor can extend through the ferrule. A seal and/or electrical insulator can be disposed between the ferrule and the conductor. A hermetically sealed ferrule configured as such can maintain hermeticity of the case while allowing an electrical signal to enter the case. 
         [0004]    A feedthrough connector for an implantable medical device is discussed in U.S. Pat. No. 4,934,366 entitled, “Feedthrough Connector for an Implantable Medical Device.” An implantable connector that electrically connects multi-conductor leads to an implantable medical device is discussed in U.S. Pat. No. 7,736,191 entitled, “Implantable Connector with Protected Contacts.” 
         [0005]    A hermetic implantable medical device is discussed in U.S. Pat. No. 2,006,247,714 entitled, “Glass-to-metal Feedthrough Seals Having Improved Durability Particularly Under AC or DC Bias.” 
         [0006]    An optical window assembly for use in implantable medical device is discussed in U.S. Pat. No. 5,902,326 entitled, “Optical Window for Implantable Medical Devices.” 
         [0007]    These approaches have a number of shortcomings, including, but not limited to, complexity, difficulty to manufacture, and high cost. 
       OVERVIEW 
       [0008]    A ferrule can be machined from solid titanium, which can be expensive to manufacture. There is a need for improved techniques of ferrule components such as to lower the cost or increase production throughput. 
         [0009]    By way of example, this document describes housing, such as a housing for an implantable medical device, which can include a ferrule that can be configured at least partially within a first passage through the housing, which can provide for passage of an electrical connection, such as a signal, through the ferrule. The signal can be filtered by one or more components coupled to the ferrule, such as capacitors. The housing can include an interior portion, an exterior portion, and a first passage between the interior and exterior portions. The ferrule can include an outer ferrule portion oriented toward an exterior portion of the housing. The outer ferrule portion can optionally be electrically conductive. The ferrule can include an inner ferrule portion oriented toward the interior portion of the housing. The inner ferrule portion can optionally be electrically conductive. The inner ferrule portion can be formed non-integrally, or discretely from, the outer ferrule portion, and can be attached to the outer ferrule portion. The housing can be configured to carry and hermetically enclose an electronic circuit. A dielectric insert that can isolate a ferrule from electrical communication with the housing. 
         [0010]    A method can include forming an outer ferrule portion sized or shaped or otherwise configured to fit into a passage between the interior and exterior portions of a housing of an implantable medical device. The outer ferrule portion can be disposed proximal the exterior portion of the housing. The method can include forming an inner ferrule portion sized or shaped or otherwise configured to fit into a passage between an interior and exterior portion of the housing of the implantable medical device. The inner ferrule portion can be disposed proximal the interior portion of the housing. The method can include attaching the outer ferrule portion to the inner ferrule portion. The method can include providing a dielectric insert disposed at least partially inside the passage. The method can include providing an electrical conductor through the dielectric insert, such as through the passage. 
         [0011]    Forming the outer ferrule portion can include stamping a sheet such as a web. In an example, a first stamped web carries a plurality of the outer ferrule portions. Forming an inner ferrule portion can also include stamping a sheet such as a web. In an example, a second stamped web carries a plurality of inner ferrule portions. Forming the ferrule can include attaching the outer ferrule portion to the inner ferrule portion, such as by joining the first web with the second web during a roll-to-roll process. In an example, a plurality of outer ferrule portions can be attached to the first web and a plurality of inner ferrule portions can still be attached to the second web. The two webs can be attached in a roll-to-roll process resulting in a plurality of assembled ferrules, each including an inner ferrule fixed to an outer ferrule. 
         [0012]    In an example, a dielectric insert can be provided for mating to one or both the inner and outer ferrule such as to provide insulation between various portions of the outer ferrule or the inner ferrule. In some examples, the insert can be provided as part of a process such as a reel-to-reel manufacturing process. Providing the dielectric insert can include providing a plurality of dielectric inserts while the first web is positioned with respect to the second web. For example, the plurality of outer ferrule portions can be attached to the first web, and the plurality of inner ferrule portions can be attached to the second web, while a third web, with dielectric inserts, is positioned, such as between them, to dispose the dielectric insert in the ferrule. 
         [0013]    Some examples include providing an electrical conductor through the dielectric insert to provide a conductive path through the ferrule in electrical isolation from one or both of the inner ferrule portion and the outer ferrule portion. In an example, providing the electrical conductor through the dielectric insert can include providing a plurality of electric conductors through respective dielectric inserts while the plurality of outer ferrule portions are attached to the first web and the plurality of inner ferrule portions are attached to the second web. 
         [0014]    In an example, a method can include separating individual attached outer and inner ferrule portions from the first and second webs, respectively. A method can include disposing an connected outer and inner ferrule portion within a first passage of a housing of an implantable medical device. 
         [0015]    A portion of a ferrule, such as the inner ferrule portion, can include one or more biases, such as spring biases or spring fingers, which can be interference fit against an interior wall of the housing of the implantable medical device. Such a spring bias can draw the outer ferrule portion toward an exterior of the housing of the implantable medical device. It can be useful to hold the ferrule in place while the ferrule is being attached and/or sealed to the housing. 
         [0016]    Some examples include a one-piece ferrule. The inner portion and outer portion of the above referenced approach can be formed of the same continuous or monolithic material. The one-piece ferrule can be located at least partially within a passage such as a passage that extends from the interior and exterior of the apparatus or the implantable medical device housing to the exterior. The ferrule can include an exterior flange leading into a tunnel that opens to an interior of the housing. The ferrule can include one or more interior tabs extending away from an interior of the tunnel, an electrically insulative insert disposed at least partially inside the tunnel and a hermetic seal disposed between the electrically insulative insert and the tunnel. The exterior flange can be configured to abut an exterior surface of the metallic housing. The exterior flange can define an exit opening. The tunnel can define a tunnel interior extending away from the exit opening and terminating at the inlet opening of the ferrule. The at least one interior tab can be configured to exert a bias against the metallic housing while the exterior flange abuts the metallic housing. 
         [0017]    A method can include stamping a sheet to define a flange and a tunnel extending away from the flange. The method can include cutting the tunnel to define at least one tab. The method can include bending the tab away from the tunnel toward a perimeter of the flange. The method can include excising an inner opening from the tunnel. The inner opening can be in communication with an opening around which the flange extends. The method can include inserting an electrically insulative insert in the tunnel. The method can include disposing a conductor through the electrically insulative insert. The method can include sealing the electrically insulative insert to the conductor. The method can include sealing the electrically insulative insert to the ferrule. 
         [0018]    An advantage of ferrules described herein is that they can be provided into two separate portions (i.e., the outer and inner ferrule portions), each of which can be manufactured by stamping. The stamped outer and inner ferrule portions can remain on webs to aid in the manufacturing process. Such a process can provide increased production throughput by using webs, and potentially, a reel-to-reel process can be used to input one or more webs and output finished ferrules. 
         [0019]    Another advantage of the ferrules described herein is that they can provide for lower component cost versus machining approaches, which can significantly lower expenses for manufacturers. 
         [0020]    Another advantage of ferrules described herein is that they can assist in welding a ferrule to the implantable medical device housing. 
         [0021]    Some ferrules described herein can be formed as one-piece ferrules, such as by stamping. Such a one-piece ferrule can be made using a progressive stamping process, which can yield high throughput with lower cost. 
         [0022]    Another advantage of the ferrules disclosed herein is that they can provide a hermetic seal for the device with an electrical conductor passing therethrough. 
         [0023]    Another advantage of ferrules described herein is that they can hold case halves together. Further, examples having a flange can material weldable to case halves. Some designs, when joined with a housing, provide a cavity for ceramic to be disposed in and gold braze to flow into. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0024]    The drawings illustrate generally, by way of an example, but not by a way of limitation, various embodiments discussed in the present document. 
           [0025]      FIG. 1  is a schematic cutaway view diagram of an IMD incorporating a ferrule, according to an example. 
           [0026]      FIG. 2  is a perspective view diagram of an outer ferrule portion, according to an example. 
           [0027]      FIG. 3  is a perspective view diagram of an inner ferrule portion, according to an example. 
           [0028]      FIG. 4  is a perspective view diagram of a dielectric insert, according to an example. 
           [0029]      FIG. 5  is a perspective view diagram of a ferrule, according to an example. 
           [0030]      FIG. 6  is a cross-sectional view diagram of  FIG. 5  taken along an axis  6 - 6 , according to an example. 
           [0031]      FIG. 7  is a diagram of a method of manufacturing a ferrule, according to an example. 
           [0032]      FIG. 8  is a perspective view diagram of multiple outer ferrule portions adhered to a first web, according to an example. 
           [0033]      FIG. 9  is a perspective view diagram of multiple inner ferrule portions adhered to a second web, according to an example. 
           [0034]      FIG. 10  is a perspective view diagram of multiple ferrules and a first and a second web, according to an example. 
           [0035]      FIG. 11  is a perspective view diagram of a first and a second web with ferrules stamped out, according to an example. 
           [0036]      FIG. 12  is a perspective view diagram of multiple ferrules separated from the first and the second web of  FIG. 11 . 
           [0037]      FIG. 13A  is a perspective view of a one-piece ferrule, according to an example. 
           [0038]      FIG. 13B  is a top view diagram of the one-piece ferrule of  FIG. 13A . 
           [0039]      FIG. 13C  is a front view diagram of the one-piece ferrule of  FIG. 13A . 
           [0040]      FIG. 13D  is a perspective view diagram of a part of the one-piece ferrule of  FIG. 13A . 
           [0041]      FIG. 13E  is a side view diagram of the one-piece ferrule of  FIG. 13A . 
           [0042]      FIG. 13F  is an enlarged view of the portion marked  13 F in  FIG. 13E , according to an example. 
           [0043]      FIG. 14A  is a perspective view diagram of an electrical insulative insert placed in a one-piece ferrule, according to an example. 
           [0044]      FIG. 14B  is a cross sectional side view taken along an axis  14 B- 14 B in  FIG. 14A , according to an example. 
           [0045]      FIG. 15A  is a perspective view diagram of a ferrule coupled to a circuit, according to an example. 
           [0046]      FIG. 15B  is a schematic diagram of a ferrule coupled to a circuit, according to an example. 
           [0047]      FIG. 16  is a diagram of a method of manufacturing a one piece ferrule assembly including a one piece ferrule, according to an example. 
       
    
    
     DETAILED DESCRIPTION 
       [0048]      FIG. 1  is a schematic cutaway view diagram illustrating generally, by way of an example, but not by way of limitation, an implantable medical device (“IMD”)  100  incorporating a ferrule  108  such as a capacitive filter ferrule. The IMD  100  can include a header  102 , a housing  104 , and one or more electronic circuits such as a printed circuit board (PCB) or a hybrid circuit (e.g., one formed at least in part of flex-circuit) or other circuit  106 . The hybrid circuit  106  can be a miniaturized electronic circuit manufactured of individual devices, such as semiconductor devices (e.g. transistors and diodes) and passive components (e.g. resistors, inductors, transformers, and capacitors), attached to a substrate or printed circuit board (PCB). 
         [0049]    The header  102  can be coupled to one or more other implantable components, such as a lead  110 . The 1 MB  100  can be operated with one or more leads such as the lead  110  such as, for example, for conveying cardiac electrostimulation or neurostimulation, or impedance or other conductivity characteristic measurement test energy from the 1 MB  100 , or for conveying one or more electric cardiac or other signals from the heart to a sensing circuitry of the IMD  100 . The housing  104  can include an interior portion  112 , an exterior portion  114 , and a first passage  116  between the interior  112  and exterior  114  portions, respectively, of the housing  104 . The circuit  106  can be disposed within a hermetically-sealed interior portion  112  of the housing  104 . The ferrule  108  can be affixed or otherwise coupled to the housing  104 , and can extend partially within the first passage  116  (between the interior and exterior portions  112  and  114 , respectively, of the housing  104 ) such as to allow capacitively-filtered or other passage of an electrical current via an electrical conductor. 
         [0050]    In an example, the ferrule  108  can be a one-piece ferrule as illustrated in  FIG. 13 . In an example, the ferrule  108  can be a two piece ferrule  108 ′ as illustrated in  FIGS. 2-3 . An IMB  100  can include a header  102  that can enclose a portion of the ferrule  108 ′ extending out of the housing  104 . The header  102  can couple a terminal block on a proximal end of the lead  110  to a circuit  106  via the ferrule  108 ′. 
         [0051]    A circuit  106  can electrically couple to the portion of the ferrule  108 ′ that extends within the interior portion  112  of the housing  104 . During operation of the IMD  100 , the circuit  106  can communicate with an electrode at the distal end of the lead  110  by way of the ferrule  108 ′. The housing  104  of the IMD  100  can include or can be formed of a biocompatible material, such as titanium. In an example, one or more biocompatible materials, such as niobium, platinum, or one or more other biocompatible materials can be used. 
         [0052]    Referring now to  FIGS. 2 and 3 , the two portions of the two piece ferrule are described.  FIG. 2  is a perspective view diagram illustrating generally, by way of an example, but not by way of limitation, an outer ferrule portion  200 . In an example, the outer ferrule portion  200  can be electrically-conductive. The outer ferrule portion  200  can be stamped from a suitable material, such as sheet metal, or can be formed in another way. The outer ferrule portion  200  can include or can be composed of an electrically-conductive biocompatible material, such as titanium. One or more other materials such as one or more of niobium, niobium-titanium alloy, titanium-6Al-4V alloy, platinum, iridium, molybdenum, zirconium, tantalum, vanadium, tungsten, palladium, nickel super alloy, alloys, mixtures, and/or one or more combinations thereof can be used for manufacturing the outer ferrule portion  200 . The outer ferrule portion  200  can be shaped like a rectangular frame defining a rectangular opening  204 , or can have another shape. Although not a requirement, the outer ferrule portion  200  can be made of a biocompatible material, such as the same material as the housing  104  of the 1 MB  100 , such as for facilitating attachment to the exterior portion  114  of the housing  104 . The outer ferrule portion  200  can include a drawn or extruded or otherwise formed seat portion  202  sized or shaped or otherwise configured to fit within a passage such as first passage  116 . A snug fit can be provided, which can help form a hermetic seal between the seat portion  202  and the first passage  116  of the housing  104 . The snug fit can permit welding or brazing the electrically-conductive outer ferrule portion  200  to the exterior portion  114  of the housing  104 . 
         [0053]      FIG. 3  is a perspective view diagram illustrating generally, by way of an example, but not by way of limitation, an inner ferrule portion  300 . The inner ferrule portion  300  can be stamped from a suitable material, such as sheet metal, or can be formed in another way. The inner ferrule portion  300  can include or can be composed of an electrically-conductive material, such as titanium. One or more other materials such as one or more of niobium, niobium-titanium alloy, titanium-6Al-4V alloy, platinum, iridium, molybdenum, zirconium, tantalum, vanadium, tungsten, palladium, nickel super alloy, or one or more alloys, mixtures, or combinations thereof can be used for manufacturing the inner ferrule portion  300 . The inner ferrule portion  300  can be shaped like a rectangular frame. The inner ferrule portion  300  can be similar to the shape of the outer ferrule portion  200 . The length of the inner ferrule portion  300  and the length of the outer ferrule portion  200  can be the same or different. The width of the outer ferrule portion  200  can exceed the width of the inner ferrule portion  300 . The width of the outer ferrule portion  200  can be less than the width of the inner ferrule portion  300 . The inner ferrule portion  300  can be made of a biocompatible material or of one or more non-biocompatible materials, such as to reduce the manufacturing cost. 
         [0054]    The inner ferrule portion  300  can include at least one member or tab such as an elastically flex tab  302  that can extend outward, away from an inner ferrule portion opening  308 . The flex tab  302  can be made of a flexible or resilient material that can be flexed (e.g., inelastically deformed to assume and retain a new shape) upward or away from a frame of the inner ferrule portion  300  during the stamping process.  FIG. 3  depicts an example in which the inner ferrule portion  300  can include four flex tabs similar to the flex tab  302 , but more or a fewer flex tabs  302  can be used. The inner ferrule portion  300  and the outer ferrule portion  200  can be two separate portions that can be attached to each other, or each can be attached to the housing  104 . The outer ferrule portion  200  can be attached to the inner ferrule portion  300 . The inner ferrule portion  300  can be formed non-integrally with the outer ferrule portion  200 , but can be attached to the outer ferrule portion  200 . The inner ferrule portion  300  can be electrically-conductive and can include an electrically-conductive tab  304 . The electrically-conductive tab  304  can include a second passage  306 . The second passage  306  can be sized or shaped for passing an electrical conductor (e.g., as described below in conjunction with  FIG. 5 ). The second passage  306  can permit an electrical connection between the electrical conductor and the electrically-conductive tab  304 . The electrical conductor can be made of a material that can include, but is not limited to, one or more of tantalum, niobium, titanium, molybdenum, copper, or one or more alloys of any of these. 
         [0055]      FIG. 4  is a perspective view diagram illustrating generally, by way of an example, but not by way of limitation, an insert such as a dielectric insert  400 .  FIG. 4  depicts an example that can include one or a plurality of lumens such as through lumens  402 . The lumens  402  can pass the respective electrical conductors. More or a few through lumens  402  or conductors (than that shown in  FIG. 4 ) can be employed. The dielectric insert  400  can be at least partially disposed between and carried within the outer ferrule portion  200  and the inner ferrule portion  300 . The dielectric insert  400  can operate to electrically isolate the electrical connection of a conductor passing through the lumens  402  from the electrically-conductive outer ferrule portion  200 . The dielectric insert  400  can include a recess  404 . The recess  404  can be sized or shaped or otherwise configured to receive a tab such as the electrically-conductive tab  304  of the inner ferrule portion  300 . This can permit an electrically-conductive element to pass through the lumens  402  in the electrically-conductive tab  304  and the recess  404 . In an example, the dielectric insert  400  can be metalized. Metalizing can be accomplished by sputtering a thin layer of metal such as titanium onto the dielectric insert  400 . Other metals can also be used in metalizing. Metalizing the dielectric insert  400  can improve a brazing operation to join the dielectric insert  400  to another component, such as the ferrule  108 ′. 
         [0056]    Conductive portions isolated by the non-conducting dielectric insert  400  can provide a capacitor structure. The capacitive structure can be disposed within the housing  104  and partially disposed within the ferrule  108 ′. The capacitive structure can be operatively coupled to a distal portion of the conductor. This capacitor can help filter unwanted electromagnetic interference (e.g., EMI) from passing through a feedthrough to which the outer ferrule portion  200  and inner ferrule portion  300  can be coupled. The dielectric insert  400  can include or can be composed of a ceramic material such as the one or more of alumina, co-fired alumina, boron nitride, or another ceramic material. 
         [0057]      FIG. 5  is a perspective view diagram illustrating generally, by way of an example, but not by way of limitation, the ferrule  108 ′. The ferrule  108 ′ can include an electrically-conductive outer ferrule portion  200 , an electrically-conductive inner ferrule portion  300 , one or more conductors  502 , and a dielectric insert  400 , as described herein. The electrically-conductive outer ferrule portion  200  can be configured to be located on the exterior portion  114  of the housing  104 . The inner ferrule portion  300  can be configured to be located within the interior portion  112  of the housing  104 . The outer ferrule portion  200  can be attached to the inner ferrule portion  300 . The outer ferrule portion  200  can be welded or affixed to the inner ferrule portion  300 , such as through joining, such as by a laser weld or another coupling. The outer ferrule portion  200  can be vacuum-fused or otherwise affixed to the inner ferrule portion  300 . One or more other joining techniques can be employed, such as brazing or another joining technique. 
         [0058]    The dielectric insert  400  can be at least partially disposed within a frame provided by the outer ferrule portion  200  and the frame provided by the inner ferrule portion  300 . The dielectric insert  400  can be hermetically attached to the one or both of the outer ferrule portion  200  and the inner ferrule portion  300 , such as by brazing or welding. The dielectric insert  400  can extend into the interior of the housing. The dielectric insert  400  can extend out of the housing to an exterior region. 
         [0059]    The outer ferrule portion  200  can include a stamped sheet metal portion that can be sized or shaped to accept a portion of the dielectric insert  400  within the frame provided by the outer ferrule portion  200 . The inner ferrule portion  300  can also include a stamped sheet metal portion that can be sized or shaped to accept a portion of the dielectric insert  400  within the frame provided by the inner ferrule portion  300 . The dielectric insert  400  can operate to electrically isolate one or more conductors  502  from the electrically-conductive outer ferrule portion  200 . 
         [0060]    In the example of  FIG. 5 , one or more conductors  502  can pass through respective apertures in the dielectric insert  400 . The one or more conductors  502  can extend through the dielectric insert  400 , which can be disposed within the frame provided by the outer ferrule portion  200  and the inner ferrule portion  300 . One or more conductors  502  can be hermetically sealed within respective apertures in the dielectric insert  400 , such as by brazing or another technique suitable for providing such a seal. 
         [0061]    The ferrule  108 ′ can be configured to be located at least partially within the first passage  116  (between the interior and exterior portions  112  and  114 , respectively, of the housing  104 ). The ferrule  108 ′ can allow for capacitively-filtered or other passage of signals along the one or more conductors  502  between electronics in the housing  104  to electronics or other loads outside and the housing  104 . 
         [0062]      FIG. 6  is a cross-sectional view diagram of  FIG. 5  taken along an axis  6 - 6 , according to an example. The ferrule  108 ′ can include or can be composed of an electrically-conductive, biocompatible material such as titanium, similar to the material used to construct the housing  104  of the IMD  100 . The ferrule  108 ′ can be sized or shaped or otherwise adapted to mate with the interior and exterior portions  112  and  114 , respectively, of the housing  104  that can be adjacent to the first passage  116  such as for allowing the capacitively-filtered or other passage of the one or more conductors  502  within the first passage  116 . The ferrule  108 ′ can be hermetically attached to the housing  104  such as by welding or brazing or another attachment technique. The electrically-conductive outer ferrule portion  200  can be configured to be hermetically attached or otherwise attached to the exterior portion  114  of the housing  104 . 
         [0063]    The inner ferrule portion  300  can be configured to exert a bias against a portion of the interior portion  112  of the housing  104 . The inner ferrule portion can be disposed adjacent to the first passage  116 . The inner ferrule portion  300  can include the flex tab  302  (e.g., as discussed with respect to  FIG. 2B ) that can be configured to be bent toward the outer ferrule portion  200  such as shown in  FIG. 6 . The adjacent regions of the interior and exterior portions  112  and  114 , respectively, of the housing  104  can be configured to be inserted into a space or slot  602  that can be provided laterally between the coupled outer ferrule portion  200  and the inner ferrule portion  300 . Two halves of a clamshell shaped housing can be closed around the ferrule  108 ′, disposed in the slot  602 . 
         [0064]    Adjacent portions of the housing  104  can exert a force on the flex tab  302  of the inner ferrule portion  300 . This can enable the flex tab  302  of the inner ferrule portion  300  to flex to generate a biasing force against the portions of the housing  104  of the IMD  100 , such as to draw the outer ferrule portion  200  toward or against the exterior portion  114  of the housing  104 . This can be helpful in holding the ferrule in place. The biasing force can aid in holding the outer ferrule portion  200  flush against the exterior portion  114  of the housing  104  and can help secure the ferrule  108 ′ such as during welding or otherwise affixing of the outer ferrule portion  200  to the housing  104  of the IMD  100 . After such welding or other hermetically-sealing affixation of the outer ferrule portion  200  to the housing  104 , the flex tab  302  may straighten such as to extend laterally outward due to the biasing force. 
         [0065]    The dielectric insert  400  can be partially disposed within a peripheral frame  604  provided by the outer ferrule portion  200  and the inner ferrule portion  300 , respectively, and can be hermetically attached to the outer ferrule portion  200  and the inner ferrule portion  300 , respectively. The dielectric insert  400  can be further configured to fit within a lateral peripheral dimension of the first passage  116  between the interior and exterior portions  112  and  114 , respectively, of the housing  104 . 
         [0066]    In this example, the circuit  106  can be adapted to receive or otherwise be electrically connected to the one or more conductors  502 . In an example, the conductors  502  can be soldered or welded or otherwise electrically and mechanically connected to a conductive pad or terminal on the circuit  106 . 
         [0067]      FIG. 7  is a diagram illustrating generally, by way of an example, but not by way of limitation, a method of manufacturing a ferrule such as the ferrule  108 ′. At  700 , an electrically-conductive outer ferrule portion  200  can be formed to include one or more stamped sheet metal portions (e.g., those discussed in conjunction with  FIGS. 2, 5, and 6 ). This can include stamping a titanium or other metal sheet, such as to form the one or more stamped sheet metal portions of the outer ferrule portion  200  for creating a passage through the sheet, which can be stamped to be sized or shaped or otherwise configured to be located toward and welded or brazed to the exterior portion  114  of the housing  104 . 
         [0068]    At  702 , an electrically-conductive inner ferrule portion  300  can be formed, such as to include one or more stamped sheet metal portions (such as discussed in conjunction with  FIGS. 3, 5, and 6 ). This can include stamping a titanium or other metal sheet, such as to form the one or more stamped sheet metal portions of the inner ferrule portion  300  for creating a passage through the sheet, which can be stamped to be sized or shaped or otherwise configured to be attached and sealed at the interior portion  112  of the housing  104 , such as by welding or brazing. At  702 , the stamping of the inner ferrule portion  300  can include or can be accompanied by stamping the metal sheet to form a flex tab  302  (such as discussed above), such as for extending toward and biasing against a portion of an interior portion  112  of the housing  104 . 
         [0069]    At  704 , the outer ferrule portion  200  and the inner ferrule portion  300  can be attached. In an example, the outer ferrule portion  200  can be attached to the inner ferrule portion  300  by a laser weld or other welding or attachment technique. In an example, the outer ferrule portion  200  can be vacuum-fused or otherwise attached to the inner ferrule portion  300 . In an example, one or more other attachment techniques, such as brazing or any other attachment technique can be used. 
         [0070]    At  706 , a dielectric insert  400  can be provided such that the dielectric insert  400  is captured partially within the lateral peripheral frame provided by the outer  200  and the inner ferrule portion  300  (such as discussed above in  FIGS. 4 and 5 ). 
         [0071]    At  708 , one or more conductors  502  can be provided through the dielectric insert  400 . One or more conductors  502  can pass through a respective aperture in the dielectric insert  400 . The conductors  502  that are located within a respective aperture through the dielectric insert  400  can be hermetically sealed within aperture in the dielectric insert  400  such as by brazing or another technique suitable for such sealing. The one or more conductors  502  can extend through the dielectric insert  400 , which can be disposed within the frame provided by the outer ferrule portion  200  and the inner ferrule portion  300  (such as discussed above in  FIGS. 4 and 5 ). An electrically-conductive outer ferrule portion  200  can be formed to include one or more stamped sheet metal portions (such as discussed in conjunction with  FIGS. 2, 5, and 6 ) 
         [0072]    The above described order of steps of the method is an example. The method can be performed in a different sequence of steps other than that described above. For example, the one or more conductors  502  can first be provided through the dielectric insert  400 . The method then can include providing the electrically-conductive outer ferrule portion  200  and the electrically-conductive inner ferrule portion  300 . The method can further include attaching the outer ferrule portion  200  and the inner ferrule portion  300 . Then, the dielectric insert  400  can be captured partially within the lateral peripheral frame provided by the outer ferrule portion  200  and the inner ferrule portion  300  (such as discussed above in  FIGS. 4 and 5 ). 
         [0073]    The above description has emphasized an example of a procedure with respect to making a single or particular ferrule  108 ′. However, multiple outer ferrule portions such as the outer ferrule portion  200  (such as shown in  FIG. 8 ) and multiple inner ferrule portions such as the inner ferrule portion  300  (such as shown in  FIG. 9 ) can be serially or concurrently fabricated. This can result in multiple productions of multiple ferrules such as the ferrule  108 ′ (such as shown in  FIG. 10 ). 
         [0074]    At  700 , stamping an electrically-conductive outer ferrule portion  200  can include stamping a metal sheet. The stamping can be used for forming a plurality of the outer ferrule portion  200 , which can be joined by a first web  802  after such stamping. Thus, the first web  802  can carry a plurality of the outer ferrule portion  200 . 
         [0075]    At  702 , stamping an electrically-conductive inner ferrule portion  300  at  702  can include stamping a metal sheet. The stamping can be used for forming a plurality of the inner ferrule portions such as the inner ferrule portion  300 , which can be joined by a second web  902  after such stamping. Thus, the second web  902  can carry a plurality of the inner ferrule portion  300 . 
         [0076]    At  704 , the outer ferrule portion  200  can be attached to the respective inner ferrule portion  300 . Such attaching can be carried out while the first web  802  is positioned with respect to the second web  902 , with the plurality of outer ferrule portion  200  still attached to the first web  802 , and with the plurality of inner ferrule portion  300  still attached to the second web  902 . 
         [0077]    At  706 , a plurality of dielectric inserts similar to the dielectric insert  400  can be provided while the first web  802  is positioned with respect to the second web  902 . Also, the plurality of outer ferrule portion  200  can still be attached to the first web  802 . Further, the plurality of inner ferrule portions such as the inner ferrule portion  300  can still be attached to the second web  902 . 
         [0078]    At  708 , a plurality of one or more conductors  502  can be provided through respective dielectric insert  400  while the plurality of outer ferrule portion  200  can be still attached to the first web  802  and the plurality of inner ferrule portion  300  can be still attached to the second web  902 . The respectively individually attached outer ferrule portion  200  and the inner ferrule portion  300  can be separated from the first web  802  and second web  902 , respectively (such as shown in  FIGS. 11 and 12 ). The respectively attached outer ferrule portion  200  and the inner ferrule portion  300  can be disposed within the first passage  116  of a housing  104  of the IMD  100  (such as discussed above). Thus, inner ferrule portion  300  can bias against an interior portion  112  of the housing  104 . This can help to draw the outer ferrule portion  200  toward an exterior portion  114  of the housing  104  of the IMD  100 , which can help provide a tight seal therebetween. The outer ferrule portion  200  can be further attached and sealed to the exterior portion  114  of the housing  104  of IMD  100 . 
         [0079]      FIG. 13A  is a perspective view illustrating generally, by way of an example, but not by way of limitation, a ferrule  108 ″. The ferrule  108 ″ can be a one-piece ferrule referred to as ferrule  108 ″. The ferrule  108 ″ can be used for providing electrical communication through a housing  104  of an IMD  100 , which can be metallic and/or hermetically sealed  1304  as discussed herein. The one-piece ferrule  108 ″ can be stamped from a suitable material, such as sheet metal, or can be formed in another way. The one-piece ferrule  108 ″ can include or can be composed of an electrically-conductive biocompatible material such as titanium. One or more other materials such as one or more of niobium, niobium-titanium alloy, titanium-6Al-4V alloy, platinum, iridium, molybdenum, zirconium, tantalum, vanadium, tungsten, palladium, nickel super alloy, and alloys, mixtures, and their alloys can be used to form the one-piece ferrule  108 ″. The one-piece ferrule  108 ″ can be shaped like a rectangular frame or can have another shape. Although not a requirement, the one-piece ferrule  108 ″ can be made of a biocompatible material, such as of the same material as the housing  104  of the IMD  100  such as for facilitating attachment to the housing  104 . The ferrule  108 ″ can be affixed or otherwise coupled to the housing  104  and can extend partially within the first passage  116  (e.g., between the interior and exterior portions  112  and  114 , respectively, of the housing  104 ). 
         [0080]    The one-piece ferrule  108 ″ can include a drawn or extruded or otherwise formed seat portion  1322 . The seat portion  1322  can be sized or shaped or otherwise configured to fit within the first passage  116 . A snug fit can be provided, which can help form the hermetic seal  1404  between the seat portion  202  and the first passage  116  of the housing  104 . The snug fit can permit welding or brazing the electrically-conductive one-piece ferrule  108 ″ to the exterior portion  114  of the housing  104 . The ferrule  108 ″ can include an exterior flange  1302  also referred to as the flange  1302  that can be configured to abut an exterior portion  114  of the metallic housing  104  such that the exterior flange  1302  can define an exit opening  1316 . 
         [0081]    The flange  1302  can include at least one carrier flash  1320 . The carrier flash  1320  can form an integral or monolithic portion of the one-piece ferrule  108 ″.  FIG. 13A  depicts an example in which the carrier flash  1320  is provided at two distinct opposite locations. However, the carrier flash  1320  can be provided at more than two or less than two locations. The spacing between the carrier flash  1320  placed at distinct locations can vary as desired. The carrier flash  1320  can be a remnant of a progressive die stamping operation. 
         [0082]    The one-piece ferrule  108 ″ can further include a tunnel  1304  that can extend from the exterior flange  1302 . The tunnel  1304  can be shaped like an oval frame or can have another shape. The tunnel  1304  can define a tunnel interior  1306  that can extend away from the exit opening  1316  and can terminate at an inlet opening  1318  of the one-piece ferrule  108 ″. The tunnel  1304  can be formed by a process comprising drawing a sheet away from the flange  1302 . The tunnel  1304  can be sized to conform to the first passage  116  through the housing. The tunnel  1304  can be notched along its length, away from the exit opening  1316 , such that at least one interior tab  1308  can extend away from a notch  1310 . The at least one interior tab  1308  can extend away from the tunnel interior  1306 . The at least one interior tab  1308  can be one of a plurality of interior tabs disposed around the tunnel  1304 . The tabs can be formed before or after the tunnel is bent or rolled proximal the inlet opening  1318 . 
         [0083]      FIG. 13A  depicts an example in which the ferrule  108 ″ can include one or more interior tabs  1308 , and corresponding notches  1310 ,  1308 , and  1310 . The at least one interior tab  1308  can be configured to exert a bias against the metallic housing  104  while the exterior flange  1302  can abut the metallic housing  104 . The at least one interior tab  1308  can be bent from material comprising the tunnel  1304 . The at least one interior tab  1308  can be made of a flexible or resilient material that can be flexed (e.g., inelastically deformed to assume and retain a new shape) upward or away from the tunnel of the ferrule  108 ″ during the stamping process. The ferrule  108 ″ can include an electrically insulative insert similar to the dielectric insert  400  disposed at least partially inside the tunnel  1304 . The hermetic seal  1404  can include gold disposed between the electrically insulative insert  400  and the tunnel  1304 . 
         [0084]    A system for providing electrical communication can include the IMD  100 . The 1 MB housing  104  can define the interior  112  and the first passage  116  that can extend from the exterior  114  of the 1 MB housing  104  to the interior  112 . The IMD  100  can further include the one-piece ferrule  108 ″ that can be made of a biocompatible material. The ferrule  108 ″ can be conformed to and joined to the first passage  116  such that the ferrule  108 ″ can extend from the exterior  114  to the interior  112  of the IMD housing  104 . The ferrule  108 ″ can include the exterior flange  1302  that can be configured to abut the exterior portion  114  of the housing  104  such that the exterior flange  1302  can define the exit opening  1316 . The ferrule  108 ″ can further include the tunnel  1304  extending from the exterior flange  1302 . The tunnel  1304  can define the tunnel interior  1306 , which can extend away from the exit opening  1316  and can terminate at the inlet opening  1318  of the ferrule  108 ″. The ferrule  108 ″ can include at least one interior tab  1308  that can extend away from the tunnel interior  1306 . The at least one interior tab  1308  can be configured to exert a bias against the housing  104  while the exterior flange  1302  can abut the housing  104 . The ferrule  108 ″ can include the electrically insulative insert  400  disposed at least partially inside the tunnel  1304  and the hermetic seal  1404  disposed between the electrically insulative insert  400  and the tunnel  1304 . 
         [0085]      FIG. 13B  is a top view diagram of an example of the one-piece ferrule  108 ″. A top surface  1314  of the exterior flange  1302  can define a recess  1312 , such that the recess  1312  encircles the exit opening  1316 . The hermetic seal  1404  can further substantially fill the recess  1312  on the top surface  1314  of the exterior flange  1302  as illustrated in  FIG. 13B . 
         [0086]      FIG. 13C  is a front view of an example of the one-piece ferrule  108 ″.  FIG. 13D  is a cross sectional perspective view diagram of an example of a part of the one-piece ferrule  108 ″. The ferrule  108 ″ can include or can be composed of the electrically-conductive, biocompatible material such as titanium, similar to the material used to construct the housing  104  of the IMD  100 . The ferrule  108 ″ can include the exterior flange  1302  that can be configured to abut the exterior portion  114  of the metallic housing  104  such that the exterior flange  1302  can define the exit opening  1316  (as illustrated in  FIG. 9D ). The one-piece ferrule  108 ″ can further include the tunnel  1304  that can extend from the exterior flange  1302 . The tunnel  1304  can define the tunnel interior  1306  that can extend away from the exit opening  1316  and can terminate at an inlet opening  1318  of the ferrule  108 ″. 
         [0087]      FIG. 13E  is a side view diagram of an example of the one-piece ferrule  108 ″.  FIG. 13F  is an enlarged view of an example of a marked portion  13 F of the one-piece ferrule  108 ″ of  FIG. 13E . The enlarged view of the exterior flange  1302  and the at least one interior tab  1308  is illustrated in  FIG. 12F . The at least one interior tab  1308  can include a flex tab that can extend laterally outward from the tunnel  1304  (as shown in  FIG. 13F ) toward a portion of the interior portion  112  of the housing  104  adjacent the first passage  116 . A bias can urge the tab  1308  against the portions of the housing  104  of the IMD  100 , such as to draw the one-piece ferrule  108 ″ toward or against the exterior portion  114  of the housing  104 . The biasing force can aid in holding the one-piece ferrule  108 ″ flush against the exterior portion  114  of the housing  104  and can help secure the one-piece ferrule  108 ″ such as during welding or other hermetically-sealing or affixation of the one-piece ferrule  108 ″ to the housing  104  of the IMD  100 . The tunnel  1304  can be formed by a process such as drawing a sheet away from the flange  1302 . The tunnel  1304  can be sized to conform to the first passage  116  through the housing  104 . 
         [0088]      FIG. 14A  is a perspective view diagram of an example of the electrically insulative insert  400  placed in the one-piece ferrule  108 ″. An example of the one-piece ferrule  108 ″ has been described above in detail in conjunction with  FIG. 13A .  FIG. 14A  depicts an example that can include one or a plurality of lumens such as through lumens  402 . The lumens  402  can pass the respective electrical conductors. More or a fewer through lumens  402  or conductors, than that shown in  FIG. 14A , can be used. The ferrule  108 ″ can further include the electrically insulative insert  400  disposed at least partially inside the tunnel  1304  and the hermetic seal  1404  disposed between the electrically insulative insert  400  and the tunnel  1304 , such as shown in  FIG. 14A . 
         [0089]    The dielectric insert  400  can be metalized. Metalizing can be accomplished by sputtering a thin layer of metal such as titanium onto the dielectric insert  400 . One or more other metals can also be used in metalizing. The electrically insulative insert  400  can be brazed to the ferrule  108 ″. Metalizing the dielectric insert  400  can improve a brazing operation to join the dielectric insert  400  to another component, such as the ferrule  108 ″. The dielectric insert  400  can operate to electrically isolate the electrical connection of the at least one of the conductors  502  passing through the lumens  402  from the electrically-conductive ferrule  108 ″. 
         [0090]    The conductive portions isolated by the non-conducting dielectric insert  400  can provide a capacitor structure. The capacitive structure can be disposed within the housing  104  and partially disposed within the ferrule  108 ″. The capacitive structure can be operatively coupled to a distal portion of the conductor. This capacitor can help filter unwanted electromagnetic interference (e.g., EMI) from passing through the feedthrough to which the ferrule  108 ″ can be coupled. The dielectric insert  400  can include or can be composed of a ceramic material such as one or more of alumina, co-fired alumina, boron nitride, or another ceramic material. The ceramic material can fit inside the ferrule and can create a hermetic seal  1404 . 
         [0091]      FIG. 14B  is an example of a cross sectional side view diagram taken along an axis  14 - 14 .  FIG. 14B  shows a part of the electrically insulative insert  400  placed in the one-piece ferrule  108 ″ with the hermetic seal  1404 . The hermetic seal  1404  can substantially fill the recess  1312 . The electrically insulative insert  400  can be brazed to the ferrule  108 ″. A brazing material can form the hermetic seal  1404  between the electrically insulative insert  400  and the ferrule  108 ″. The brazing material that can be used to maintain the electrically insulative insert  400  within the ferrule  108 ″ can be composed of any suitable braze material or materials. Examples of suitable braze materials include, but are not limited to gold, a gold alloy, or the like. The brazing material can fill in one or more gaps between the above discussed ceramic material and another component. The brazing material can fit inside the ferrule and can create a hermetic seal  1404 . The ceramic material can be metalized with titanium. The ceramic material can be metalized on its surface as well as internally, such as through pores. The titanium can bind to the outside layer of the ceramic material, such as alumina, such that it can create a metalized layer that can allow the gold to enter into that layer. 
         [0092]      FIG. 15A  is a perspective view diagram of an example of the one-piece ferrule  108 ″ coupled to the circuit  106 . The ferrule can be situated on the surface of the circuit  106 . The ferrule  108 ″ can be attached to the circuit  106  using a surface mount circuit assembly or populating technique. As illustrated in  FIG. 15A , at least one of the conductors  502  can extend through the electrically insulative insert  400  to be coupled to a respective terminal  1502  of a capacitor  1504  disposed on the circuit  106 . The capacitor  1504  can be mounted on a capacitor board  1508 . The capacitor board  1508  can be mounted flush with the circuit  106 , such as to reduce or minimize height is taken up by the capacitor board  1508 . The ferrule  108 ″ can include a ground  1506  on the circuit  106 . 
         [0093]      FIG. 15B  is a schematic illustrating generally, by way of an example, but not by way of limitation, the one-piece ferrule  108 ″ coupled to the circuit  106 . The one-piece ferrule  108 ″ can include an electrically insulative insert  400  that can be disposed at least partially inside the tunnel  1304 . At least one of the conductors  502  can extend through the electrically insulative insert  400 . The circuit  106  can be coupled to the at least one of the conductors  502 . The at least one of the conductors  502  can be one of a plurality of conductors, such as conductors  502 . Individual ones of the conductors  502  can be coupled to a respective terminal  1502  of the capacitor  1504  disposed on the circuit  106 , such as shown in  FIG. 14B . Some of the conductors  502  can be electrically coupled to a common polarity. The at least one of the plurality of conductors  502  can be in electrical communication with the metallic housing  104  and an opposite polarity terminal of each of the respective capacitors  1504 . The at least one of the conductors  502  can be one of a plurality of conductors  502  such that the circuit  106  can include a capacitive filter electrical signal carried on the plurality of conductors  502 . The at least one of the conductors  502  can be soldered or welded or otherwise electrically and mechanically connected to a conductive pad or the respective terminal  1502  on the circuit  106 . 
         [0094]      FIG. 15B  shows an example of circuitry for providing the functionality of the IMD  100 . The IMD  100  can include a pacemaker, a ICD, a defibrillator, or another medical device.  FIG. 15B  can include protection circuitry for protecting the IMD  100  from external electrical interference such as voltage or current surges at inputs provided by the feedthrough into the interior portion  112  of the housing  104 . The protection circuitry can include a capacitive filter. The capacitive filter can include a power supply filter that can be used to filter signals from other circuitry such as high voltage signals. 
         [0095]      FIG. 16  is a diagram of an example of a method of manufacturing the one-piece ferrule  108 ″ assembly. At  1600 , the ferrule  108 ″ can be formed by a stamping process, such as progressive-die stamping. The one-piece ferrule  108 ″ can be electrically conductive and can be formed to include one or more stamped sheet metal portions. This can include stamping the titanium or other metal sheet, such as to form the one or more stamped sheet metal portions of the ferrule  108 ″ for creating the first passage  116  through the sheet, which can be stamped to be sized or shaped or otherwise configured to be located toward and welded or brazed to the interior  112  and exterior  114  walls of the housing  104 . At  1600 , the sheet can be stamped to define the flange  1302 , such as with the tunnel  1304  extending away from the flange  1302 . The flange  1302  can be configured to abut the exterior portion  114  of the housing  104  (such as discussed in conjunction with  FIG. 13 ). 
         [0096]    At  1602 , the tunnel  1304  can be cut or extruded that can define the at least one tab  1308 , thereby creating at least one tab  1308  on the sides. The tunnel  1304  can be shaped like an oval frame, or can have another shape. The tunnel  1304  can be notched along its length, away from the opening such that at least one interior tab  1308  can extend away from a notch  1310 . The ferrule  108 ″ can include four interior tabs  1308 , e.g., similar to the at least one interior tab  1308  and four notches, e.g., similar to the notch  1310 , but more or fewer tabs  1308  or notches  1310  can be employed. 
         [0097]    At  1604 , the interior tab  1308  can be bent away from the tunnel  1304 , such as toward a perimeter of the flange  1302 . The at least one interior tab  1308  can extend away from the tunnel interior  1306 . 
         [0098]    At  1606 , the inlet opening  1318  from the tunnel  1304  can be excised. The inlet opening  1318  can be in communication with an opening such as the exit opening  1316  around which the flange  1302  extends. The flange  1302  defines the exit opening  1316 . 
         [0099]    At  1608 , the electrically insulative insert  400  can be inserted in the tunnel  1304 . The dielectric insert  400  can be provided such that the dielectric insert  400  is captured partially within the frame provided by the ferrule  108 ″ (such as discussed above in  FIG. 12 ). 
         [0100]    At  1610 , at least one of the conductors  502  can be disposed through the electrically insulative insert  400 . The at least one of the conductors  502  can pass through a respective aperture or lumens  402  in the dielectric insert  400 . 
         [0101]    At  1612 , the electrically insulative insert  400  can be sealed to the at least one of the conductors  502 . The conductors  502  that are located within the respective aperture or lumen  210  through the dielectric insert  400  can be hermetically sealed within the aperture or lumen  210  in the dielectric insert  400 , such as by brazing or another technique suitable for such sealing. The braze material used to maintain the electrically insulative insert  400  within the ferrule  108 ″ can be composed of any suitable material or materials. Examples of suitable braze materials include, but are not limited to, gold, a gold alloy, or the like. 
         [0102]    At  1614 , the electrically insulative insert  400  can be sealed to the ferrule  108 ″. The dielectric insert  400  can be metalized. Metalizing can be accomplished by sputtering the thin layer of metal such as titanium onto the dielectric insert  400 . One or other metals can be used in metalizing. Metalizing the dielectric insert  400  can improve a brazing operation to join the dielectric insert  400  to another component, such as the ferrule  108 ″ (such as discussed in conjunction with  FIG. 14A ). 
         [0103]    The method can further include pinching the wall of the housing  104  between the at least one tab  1308  and the flange  1302 , such as under a bias exerted by elastic deformation of the tab  1308 . The at least one interior tab  1308  can be made of a flexible or resilient material that can be flexed. The method can include forming the housing  104  by joining two cup-shaped housing shells  118 A and  118 B. The method can include joining the two cup-shaped housing shells  118 A and  118 B such that the two cup-shaped housing shells  118 A and  118 B can define the first passage  116  that can extend from the exterior  114  of the housing  104  to the interior  112  of the housing  104 . The method can include disposing two cup-shaped housing shells  118 A and  118 B together to define the passage. One of the shells can include a stepped portion sized to fit in the other shell. At least one tab  1308  can bias the ferrule  108 ″, such as to adjust the flange  1302  against the exterior  114  of the two cup-shaped housing shells  118 A and  118 B. The method can include joining the flange  1302  to the housing  104  by a welding technique such as laser welding. 
         [0104]    A potential advantage of the ferrule  108 ′ can be that it can be provided in two separate portions, (e.g., the outer portion  200  and inner ferrule portion  300 ), each of which can be manufactured by stamping. The stamped outer and inner ferrule portions  200  or  300  can remain on a web, such as to help improve throughput or otherwise aid in the later steps of the manufacturing process. Such a process can provide increased production throughput by using a web, and optionally, a reel-to-reel process to input one or more webs and output finished ferrules. 
         [0105]    Another potential advantage of the stamped outer and inner ferrule portions  200  or  300  can be that the stamped outer or inner ferrule portions  200  or  300  can provide lower component cost than a more time-consuming precision machining process. This can lower the expense to manufacture a device using the ferrule. 
         [0106]    Another potential advantage of the stamped outer and inner ferrule approach can be that the stamped outer and inner ferrule portions can potentially assist in a better welding of the stamped outer and inner ferrule portions to the implantable medical device housing. 
         [0107]    A potential advantage of the ferrule described herein can be that it can be provided as one-piece, such as can be manufactured by stamping. This one-piece ferrule can be made in a progressive stamping process, which can yield high throughput with low cost. 
         [0108]    A potential advantage of the one-piece ferrule can be that it can fulfill a basic function of some ferrule designs, e.g., can provide a hermetic seal for the device with an electrical conductor passing therethrough. The one-piece ferrule can use one integral or monolithic stamped piece. 
         [0109]    A potential advantage of the one-piece ferrule can be that it can hold case halves and ferrule flange  1302  together, such as to provide contact for welding or to provide a cavity, such as for ceramic or gold braze. 
       Various Notes &amp; Examples 
       [0110]    Example 1 can include or use an apparatus for providing electrical communication through housing that is metallic and hermetically sealed. The subject matter can include a one-piece ferrule that is biocompatible. The ferrule can be configured to be located at least partially within a passage extending from an interior and exterior of an implantable medical device housing to an exterior. The ferrule can include an exterior flange configured to abut an exterior surface of the metallic housing, the exterior flange defining an exit opening. The ferrule can include a tunnel extending from the exterior flange, the tunnel defining a tunnel interior extending away from the exit opening and terminating at inlet opening of the ferrule. The ferrule can include at least one interior tab extending away from an interior of the tunnel, the at least one interior tab configured to exert a bias against the metallic housing while the exterior flange abuts the metallic housing. The ferrule can include an electrically insulative insert disposed at least partially inside the tunnel. The ferrule can include a hermetic seal disposed between the electrically insulative insert and the tunnel. 
         [0111]    Example 2 optionally includes the subject matter of any of the preceding examples, wherein the flange can include at least one carrier flash. 
         [0112]    Example 3 optionally includes the subject matter of any of the preceding examples, wherein the tunnel can be notched along its length, away from the opening, with the at least one interior tab extending away from the notch. 
         [0113]    Example 4 optionally includes the subject matter of any of the preceding examples, wherein the at least one interior tab is bent from material comprising the tunnel. 
         [0114]    Example 5 optionally includes the subject matter of any of the preceding examples, wherein the at least one interior tab is one of a plurality of interior tabs disposed around the tunnel. 
         [0115]    Example 6 optionally includes the subject matter of any of the preceding examples, wherein the hermetic seal includes gold. 
         [0116]    Example 7 optionally includes the subject matter of any of the preceding examples, wherein a top surface of the exterior flange defines a recess encircling the exit opening. 
         [0117]    Example 8 optionally includes the subject matter of any of the preceding examples, wherein the hermetic seal substantially fills the recess. 
         [0118]    Example 9 optionally includes the subject matter of any of the preceding examples, wherein the at least one conductor is one of a plurality of conductors, and wherein each of the conductors is coupled to a respective terminal of a capacitor disposed on the circuit. 
         [0119]    Example 12 optionally includes the subject matter of any of the preceding examples, wherein some of the conductors are electrically coupled to a common polarity. 
         [0120]    Example 13 optionally includes the subject matter of any of the preceding examples, wherein at least one of the plurality of conductors is in electrical communication with the metallic housing and an opposite polarity terminal of each of the respective capacitors. 
         [0121]    Example 14 optionally includes the subject matter of any of the preceding examples, wherein the at least one conductor is one of a plurality of conductors, wherein the circuit comprises a capacitive filter electrical signals carried on the plurality of conductors. 
         [0122]    Example 15 optionally includes the subject matter of any of the preceding examples, wherein the ferrule is stamped. 
         [0123]    Example 16 optionally includes the subject matter of any of the preceding examples, wherein the at least one interior tab is a flex tab extending laterally outward from the tunnel and toward and against a portion of an interior wall of the housing adjacent the passage. 
         [0124]    Example 17 optionally includes the subject matter of any of the preceding examples, wherein the tunnel is formed by a process comprising drawing a sheet away from the flange. 
         [0125]    Example 18 optionally includes the subject matter of any of the preceding examples, wherein the tunnel is sized to conform to the passage through the housing. 
         [0126]    Example 19 optionally includes the subject matter of any of the preceding examples, including forming a ferrule, by stamping a sheet to define a flange, with a tunnel extending away from the flange. The example can include cutting the tunnel to define at least one tab. The example can include bending the tab away from the tunnel, toward a perimeter of the flange. The example can include excising an inner opening from the tunnel, the inner opening in communication with an opening around which the flange extends. The example can include inserting an electrically insulative insert in the tunnel. The example can include disposing a conductor through the electrically insulative insert. The example can include sealing the electrically insulative insert to the conductor. The example can include sealing the electrically insulative insert to the ferrule. 
         [0127]    Example 20 optionally includes the subject matter of any of the preceding examples, wherein stamping includes progressive-die stamping. 
         [0128]    Example 21 optionally includes the subject matter of any of the preceding examples, including pinching a wall of a housing between the at least one tab and the flange under a bias exerted by elastic deformation of the tab. 
         [0129]    Example 22 optionally includes the subject matter of any of the preceding examples, including forming the housing by joining two cup-shaped housing shells. 
         [0130]    Example 23 optionally includes the subject matter of any of the preceding examples, wherein pinching the passage is irregular, with opposing steps defined between the two cup-shaped housing shells, wherein the at least one tab biases the ferrule to adjust the flange against the exterior of the two cup-shaped housing shells. 
         [0131]    Example 25 optionally includes the subject matter of any of the preceding examples, wherein metalizing includes sputtering metal onto the electrically insulative insert. 
         [0132]    Example 30 optionally includes the subject matter of any of the preceding examples, wherein the metal includes titanium. 
         [0133]    Example 31 optionally includes the subject matter of any of the preceding examples, wherein sealing includes brazing. 
         [0134]    Example 32 optionally includes the subject matter of any of the preceding examples, wherein brazing includes brazing with gold. 
         [0135]    Example 33 optionally includes a system including an implantable medical device housing defining an interior and a passage extending from an exterior of the implantable medical device housing to the interior. The example can include a one-piece ferrule that is biocompatible, the ferrule conformed to and joined to the passage, the ferrule extending from the exterior to the interior of the implantable medical device housing. The ferrule can include an exterior flange configured to abut an exterior surface of the housing, the exterior flange defining an exit opening. The example can include a tunnel extending from the exterior flange, the tunnel defining a tunnel interior extending away from the exit opening and terminating at inlet opening of the ferrule. The example can include at least one interior tab extending away from an interior of the tunnel, the at least one interior tab configured to exert a bias against the housing while the exterior flange abuts the housing. The example can include an electrically insulative insert disposed at least partially inside the tunnel. The example can include a hermetic seal disposed between the electrically insulative insert and the tunnel. 
         [0136]    Example 34 optionally includes the subject matter of any of the preceding examples, including a weld attaching the outer ferrule portion to the exterior portion of the housing. 
         [0137]    Example 35 can include a medical device including a housing, including an interior portion, an exterior portion, and a first passage between the interior and exterior portions of the housing, the housing configured to carry and hermetically enclose an electronic circuit. The example can include a capacitive filter ferrule, configured to be located at least partially within the first passage between the interior and exterior portions of the housing to allow capacitively-filtered passage of an electrical connection there between, the capacitive filter ferrule including. The example can include an electrically-conductive outer ferrule portion, configured to be located toward the exterior portion of the housing. The example can include an inner ferrule portion, configured to be located toward the interior portion of the housing, the inner ferrule portion non-integrally formed with the outer ferrule portion but attached to the outer ferrule portion. The example can include the electrical connection. The example can include a dielectric plug, electrically isolating the electrical connection from the electrically-conductive outer ferrule portion. 
         [0138]    Example 36 can optionally include the subject matter of example 35, wherein the inner ferrule portion includes a flexing flange extending laterally outward within the interior portion of the housing and also extending toward and biasing against a portion of an interior wall of the housing adjacent to the first passage between the interior and exterior portions of the housing. 
         [0139]    Example 37 can optionally include the subject matter of any of examples 35-36, wherein the outer ferrule portion includes a stamped sheet metal portion that is sized and shaped to accept a portion of the dielectric plug there within and to fit snugly at least partially within the first passage between the interior and exterior portions of the housing. In the example, the inner ferrule portion can include a stamped sheet metal portion that is sized and shaped to accept a portion of the dielectric plug there within and to provide the flexing flange. 
         [0140]    Example 38 can optionally include the subject matter of any of examples 35-37, wherein the outer ferrule portion is welded to the inner ferrule portion. 
         [0141]    Example 39 can optionally include the subject matter of any of examples 35-38, wherein the outer ferrule portion is vacuum-fused to the inner ferrule portion. 
         [0142]    Example 40 can optionally include the subject matter of any of examples 35-39, wherein the outer ferrule portion includes a drawn or extruded seat portion that is sized and shaped to fit within the first passage. 
         [0143]    Example 41 can optionally include the subject matter of any of examples 35-40, wherein the inner ferrule portion is electrically-conductive and includes an electrically-conductive tab extending laterally toward an interior of the first passage between the interior and exterior portions of the housing, the electrically-conductive tab including a second passage capable of passing an electrical conductor there though so as to permit an electrical connection between the electrical conductor and the electrically-conductive tab. 
         [0144]    Example 42 can optionally include the subject matter of any of examples 35-41, wherein the dielectric plug includes a plurality of through lumens carrying respective electrical conductors. 
         [0145]    Example 43 can optionally include the subject matter of any of examples 35-42, comprising a weld attaching the outer ferrule portion to the exterior portion of the housing. 
         [0146]    Example 44 includes forming an electrically-conductive outer ferrule portion that is sized and shaped to fit about a first passage between the interior and exterior portions of a housing of an implantable medical device such that the outer ferrule portion is located toward the exterior portion of the housing. The example can include forming an inner ferrule portion that is sized and shaped to fit about the first passage between the interior and exterior portions of the housing of the implantable medical device such that the inner ferrule portion is located toward the interior portion of the housing. The example can include attaching the outer ferrule portion to the inner ferrule portion. The example can include providing a dielectric plug at least partially within the outer and inner ferrule portions. The example can include providing an electrical conductor through the dielectric plug. 
         [0147]    Example 45 optionally includes the subject matter of any examples 35-44, wherein the forming the inner ferrule portion comprises stamping a sheet to form a flexing flange sized and shaped for extending laterally outward within the interior portion of the housing and also sized and shaped for extending toward and biasing against a portion of an interior wall of the housing adjacent to the first passage between the interior and exterior portions of the housing. 
         [0148]    Example 46 optionally includes the subject matter of examples 35-45, wherein forming an electrically-conductive outer ferrule portion comprises stamping a sheet for creating a passage through the sheet, the passage sized and shaped to accept the dielectric plug, and comprising extruding or drawing the sheet to form a seat portion that is sized and shaped to fit within the first passage. 
         [0149]    Example 47 optionally includes the subject matter of examples 35-46, wherein providing the dielectric plug comprises providing a plurality of dielectric plugs while the first web is positioned with respect to the second web and while the plurality of outer ferrule portions are still attached to the first web and the plurality of inner ferrule portions are still attached to the second web. 
         [0150]    Example 48 optionally includes the subject matter of examples 35-47, wherein the providing the electrical conductor through the dielectric plug comprises providing a plurality of electric conductors through respective dielectric plugs while the plurality of outer ferrule portions are still attached to the first web and the plurality of inner ferrule portions are still attached to the second web. 
         [0151]    Example 49 optionally includes the subject matter of examples 35-49, wherein attaching and sealing the outer ferrule portion to the exterior wall of the housing of the implantable medical device comprises welding or brazing the outer ferrule portion to the exterior wall of the housing of the implantable medical device. 
         [0152]    Example 50 can optionally include the subject matter of any of examples 35-49, wherein attaching the outer ferrule portions to the respective inner ferrule portions comprises welding the outer ferrule portions to the respective inner ferrule portions. 
         [0153]    Example 51 can optionally include the subject matter of any of examples 35-50, wherein attaching the outer ferrule portions to the respective inner ferrule portions comprises vacuum fusing the outer ferrule portions to the respective inner ferrule portions. 
         [0154]    Example 52 can optionally include the subject matter of any of examples 35-51, including a housing including an interior portion, an exterior portion, and a first passage between the interior and exterior portions of the housing, the housing configured to carry and hermetically enclose an electronic circuit. The example can include a capacitive filter ferrule, configured to be located at least partially within the first passage between the interior and exterior portions of the housing to allow capacitively-filtered passage of an electrical connection there between, the capacitive filter ferrule including. The example can include an electrical connection. The example can include a dielectric plug. The example can include an electrically-conductive outer ferrule portion, configured to be located toward and welded or brazed to the exterior portion of the housing, wherein the outer ferrule portion includes a stamped sheet metal portion that is sized and shaped to accept a portion of the dielectric plug there within and to fit snugly at least partially within the first passage between the interior and exterior portions of the housing, wherein the dielectric plug, electrically isolates the electrical connection from the electrically-conductive outer ferrule portion. The example can include an inner ferrule portion, configured to be located toward the interior portion of the housing, the inner ferrule portion non-integral with the outer ferrule portion but attached to the outer ferrule portion by welding or vacuum fusing, wherein the inner ferrule portion includes a flexing flange extending laterally outward within the interior portion of the housing and also extending toward and biasing against a portion of an interior wall of the housing adjacent to the first passage between the interior and exterior portions of the housing, wherein the inner ferrule portion includes a stamped sheet metal portion that is sized and shaped to accept a portion of the dielectric plug there within and to provide the flexing flange, wherein the inner ferrule portion is electrically-conductive and includes an electrically-conductive tab extending laterally toward an interior of the first passage between the interior and exterior portions of the housing, the electrically-conductive tab including a second passage capable of passing an electrical conductor there though so as to permit an electrical connection between the electrical conductor and the electrically-conductive tab. The example can include a configuration wherein the dielectric plug includes a plurality of through lumens carrying respective electrical conductors. 
         [0155]    Each of these non-limiting examples can stand on its own, or can be combined in various permutations or combinations with one or more of the other examples. 
         [0156]    The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein. 
         [0157]    In the event of inconsistent usages between this document and any documents so incorporated by reference, the usage in this document controls. 
         [0158]    In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. 
         [0159]    Method examples described herein can be machine or computer-implemented at least in part. Some examples can include a computer-readable medium or machine-readable medium encoded with instructions operable to configure an electronic device to perform methods as described in the above examples. An implementation of such methods can include code, such as microcode, assembly language code, a higher-level language code, or the like. Such code can include computer readable instructions for performing various methods. The code may form portions of computer program products. Further, in an example, the code can be tangibly stored on one or more volatile, non-transitory, or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media can include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memories (RAMs), read only memories (ROMs), and the like. 
         [0160]    The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.