Abstract:
An electrical feedthrough, in particular for use in an electro-medical implant, having a flange enclosing at least one feedthrough bushing and at least one terminal pin enclosed by the at least one feedthrough bushing, the terminal pin having at least one section which can be joined at a lower energy in the interior of the implant.

Description:
RELATED APPLICATION 
     This patent application claims the benefit of U.S. Provisional Patent Application No. 61/318,405, filed on Mar. 29, 2010, which is hereby incorporated by reference in its entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to an electrical feedthrough, suitable, in particular, for electromedical implants, such as, but not limited to, implantable cardiac pacemakers, defibrillators, cardioverters, nerve and cerebral stimulators, hearing aids, implantable medication pumps, and/or other electrically active implants, which include a hermetically sealed housing, and batteries having a hermetically sealed housing for these electronic implants. 
     BACKGROUND OF THE INVENTION 
     Such feedthroughs typically have a flange, through use of which they are inserted into a housing wall of the electro-medical implant, preferably by a thermal joining method such as welding or soldering. An apparatus having, inter alia, a circuit board which is capable of processing or transmitting electrical signals, is located in the housing. The feedthrough has at least one feedthrough bushing, a flange enclosing the at least one feedthrough bushing, in which at least one terminal pin is seated, which is enclosed by the at least one feedthrough bushing. The terminal pin extends through the flange and the feedthrough bushing from an inner end in the interior of the housing to an outer end, which lies outside the hermetically sealed housing. The terminal pin is typically connected to the at least one feedthrough bushing and/or the at least one feedthrough bushing is typically connected to the flange using a soldered connection, preferably using a gold solder if metal coated feedthrough bushings are used, or using a biocompatible glass solder (type 8625 from Schott) if uncoated feedthrough bushings are used. In consideration of the fact that the outer end of the terminal electrode can come into contact with the body tissue surrounding the implant in a medical implant, the terminal pins are typically manufactured from a biocompatible material, such as, but not limited to, niobium (Nb), platinum (Pt), iridium (Ir), platinum/iridium alloys (Pt/Ir), tantalum (Ta), titanium (Ti), zirconium (Zr), hafnium (Hf), medical stainless steel (e.g., 316L), or alloys made of these materials. FeNi, FeNiCo, FeCr, molybdenum (Mo), tungsten (W), chromium (Cr), FeCr, vanadium (V), aluminum (Al), or other alloys made of these materials are also possible as materials for the terminal pin. It will be apparent to one of ordinary skill in the art that other materials and alloys have similar properties may be utilized for the terminal pins without departing from the spirit and scope of the present invention. 
     The feedthrough bushing is typically produced from a ceramic material, such as aluminum oxide (Al2O3). Above all in the case of terminal pins made of niobium, tantalum, or titanium, the problem exists that only welding methods come into consideration in order to produce a connection to other conductors, for example, to the terminal lines or to device electronics attached to the circuit in the interior of the implant, for the production of secure, low-resistance, mechanically stable, and long-lived electrical contacts to the described biocompatible terminal pins. The required high temperatures of the welding procedure may generate metal vapors and/or welding sprays, however, which impair the electrical insulation capability of the ceramics and/or damage the circuit boards and therefore frequently require additional protective measures. Due to these properties, reflow soldering, which is well known in the electronics sector, has simple production technology, and is efficient, is also not possible or is not readily usable with such a terminal pin. 
     In the case of the described ceramic feedthroughs having platinum/iridium terminal pins, it is known that without special protective precautions, they display problems with the detachment of the metal coating of the feedthrough bushings upon the soldering using gold solder and have poor wettability of the platinum/iridium surfaces with soft solder. As a result, the noted reflow soldering is generally unreliable. 
     Fundamentally, the coating of the pin surfaces in the case of niobium, tantalum, or titanium terminal pins on the inner side for easy wettability with soft solder for the attachment to the internal electronics is either not possible at all or is only possible with increased effort, in that metal coatings which can be soft soldered are applied using welding technology or plasma-physical pathways, for example. Surfaces or coatings which can be soft soldered on nickel, tantalum, or titanium, which are applied with the aid of fluxes or using electroplating, have been unknown up to this point. 
     A feedthrough for implantable medical devices having an integrated capacitive filter is known from U.S. Pat. No. 5,870,272, in which the electrical contacting and mechanical connection between a pin comprising niobium, for example, and an inner contact circuit with the capacitive filter interposed is produced via a complex, multistep soldering configuration using hard and soft solders. This design is too complex for feedthroughs having simple terminal electrodes, and efficient manufacturing would not be possible in the case of a corresponding layout of the feedthrough. 
     The present invention is directed toward overcoming one or more of the above-identified problems. 
     SUMMARY OF THE INVENTION 
     The present invention is based on the object of disclosing a hermetically sealed feedthrough for terminal electrodes made of a body-compatible material toward the implant outer side, which is contact-connectible in a manner having simple production on their inner end to the electronics situated there, in particular using reflow soldering. 
     This object is achieved in that the terminal pin has a biocompatible section and, in the interior of the implant, a section which can be joined at a lower energy, and preferably can be soft soldered. The inner end of the terminal pin and/or the intersection can additionally be implemented in the form of a nailhead. 
     The section of the terminal pin which can be joined at a lower energy and can preferably be soft soldered provides the advantage that the terminal pin can be joined in the interior of the implant securely and easily using lower energy—for example, lower heat energy up to 450° C., which is used above all in soft soldering processes. In particular, in a reflow process, cost-effective soft soldering can be produced simultaneously with other components on the electronic circuit board of the implant. These sections of the terminal pins may be installed together with the other components of the electrical feedthrough in the form of the at least one feedthrough bushing simultaneously in a common high-temperature soldering process, which in turn represents a particularly cost-effective mode of attachment. Furthermore, the formation of brittle phases between the section of the terminal pin and the soft solder used is avoided by use of the section of the terminal pin which can be joined at a lower energy in the interior of the implant, as otherwise formed, for example, between gold electrodes and soft solders having tin components. 
     Optionally, the sections of the terminal pin which can be joined at a lower energy may additionally also be provided with coatings which can be soft soldered particularly well, i.e., are easily wettable, having materials such as palladium (Pd), silver (Ag), copper (Cu), gold (Au), and alloys made of these materials, the coating having a layer thickness up to approximately 0.5 mm and a thickness up to approximately 200 μm in the case of a gold coating. A gold coating having this layer thickness is known not to form brittle phases together with soft soldering materials containing tin components. 
     In summary, because of the design according to the present invention of the electrical feedthrough, only biocompatible surfaces are offered toward the implant outer side and only electrode areas which can be soft soldered are offered toward the interior. The latter are capable, for example, of being processed further in a reflow soldering method for the contacting. Materials for the biocompatible section of the terminal pin are, for example, Nb, Ta, Ti, Pt, Pt/Ir, Zr, Hf, medical stainless steels such as 316L, or alloys of these materials, as well as FeNi, FeNiCo, FeCr, Mo, W, Cr, V, Al, or alloys made of these materials. Materials for the section which can be joined at lower energy are nickel, copper, palladium, gold, silver, iron, or alloys made of these materials. These alloys may also contain one or more of the following elements in addition to the listed elements: zinc (Zn), tin (Sn), cadmium (Cd), lead (Pb), antimony (Sb), arsenic (As), bismuth (Bi), phosphorus (P), silicon (Si), nitrogen (N), or beryllium (Be). One of ordinary skill in the art will appreciate that other materials and alloys have similar properties may be utilized or other implemented without departing from the spirit and scope of the present invention. 
     The section made of the above listed materials, or other similar materials, which can be joined at a lower energy can be an attachment which is located on the inner end of the terminal pin. This attachment can be implemented as a pin, on the one hand, which is advantageously located in an extension of the longitudinal axis of the terminal pin and allows the ready accommodation of further components such as filters to ensure the electromagnetic compatibility (EMC filters) in the form of capacitors because of the lack of thickened areas. Alternatively, the attachment can also be implemented as a disk or round blank, which offers larger areas to the corresponding contact points on the partner circuit board as an advantage during the reflow process and allows mechanically stronger connections having higher carrying capacities. 
     The attachment which can be joined at a lower energy is preferably attached using a joint to the biocompatible section of the terminal pin, in particular hard solder alloys containing, for example, copper (Cu), silver (Ag), copper-nickel (CuNi), copper-zinc (CuZn), copper-tin (CuSn), silver-copper (AgCu), silver-copper-zinc (AgCuZn), silver-copper-zinc-tin (AgCuZnSn), silver-copper-tin (AgCuSn), silver-copper-zinc-cadmium (AgCuZnCd), copper-phosphorus (CuP), copper-phosphorus-silver (CuPAg), or copper-gold (CuAu), using which temperature inhomogeneities during the brazing process may be compensated for. Brazing using gold solder/gold solder alloys is preferred. Further, alloys thereof having additional possible alloy additives such as Pb, Sb, As, Bi, P, N, Be, Ni are also possible. Furthermore, the attachment which can be joined at a lower energy can be soldered, welded, crimped, clamped, or glued in an electrically conductive manner on the biocompatible section of the terminal pin using a joint, but is preferably brazed using gold solder. Preferably, the joint between the biocompatible section and the attachment which can be joined at a lower energy is located inside the implant housing in relation to the connection solder. This is the preferred type of attachment, because it is simple, reliable because of a lack of brittle phases, has mechanical carrying capacity, and can be implemented simultaneously together with the further feedthrough components in the same soldering process of the feedthrough. Because this attachment occurs already before the attachment to the electrical circuit in the interior of the implant, a welding or brazing procedure can be performed therein at the joint. In a preferred embodiment, the joint can be located within the at least one feedthrough bushing. It may thus be implemented easily in the soldering process of the feedthrough because of the centering action of the feedthrough bushing and may additionally protect it from mechanical strains and further influences. Furthermore, it is particularly preferably possible to also enclose it in the glass solder. This results in more extensive protection from mechanical strains, because the joint and the adjoining pin areas are mechanically decoupled toward the exterior by the glass solder. 
     In a further preferred embodiment, the electrical feedthrough includes an outer and an inner feedthrough bushing. In this embodiment, the at least one terminal pin is connected hermetically sealed to the outer and the inner feedthrough bushings and the outer and inner feedthrough bushings are connected hermetically sealed to the flange using a soldered connection implemented as a glass plug. The glass plug is delimited by a cavity which is enclosed by the flange, and the outer and the inner feedthrough bushings. The glass solder of the type 8625 from Schott, which was cited at the beginning, is preferably used as the solder material. However, other solder materials are also contemplated. The feedthrough bushings are thus used as flow barriers during the soldering, which results in a simplification and a yield increase of the production process. In further embodiments, either the outer or the inner feedthrough bushings, or also both, may be dispensed with, if suitable materials or material combinations are selected for the flange, the terminal pins, and the glass solder for this purpose. These variants have the advantage that the soldering can be performed in a more space-saving manner than with two feedthrough bushings simultaneously. 
     The security against incident radiation in the housing and thus the prevention of the introduction of radiation is very important due to modern imaging methods and also because of the radiation present in the environment, for example, due to mobile telephones, wireless networks, magnetic resonance tomographs, and the like. For this reason, the electrical feedthrough can comprise a filter, preferably a filter capacitor, which is electrically connected to the section which can be joined at a lower energy, preferably to the pin which can be soft soldered. A shield between the flange and the at least one terminal pin is produced by the filter and the circuit lying inside the housing and the further components are thus protected against electromagnetic incident radiation. The suitable filters are typically ceramics, which are generally very sensitive to heat and fracture. Therefore, these may only be attached directly without further complex measures using a low-energy method, such as a soft soldering method. 
     Furthermore, the present invention includes a production method for an electrical feedthrough, in which the terminal pin is cooled using a heat sink during the generation of the glass solder plug. Because the terminal pin remains cooler than the glass in this case, even upon the use of terminal pin materials having coefficients of thermal expansion which are otherwise incompatible with the glass solder, the occurring thermal strains may be controlled enough that hermetically sealed soldering having mechanical carrying capacity is achieved. The heat introduction into the glass solder can be performed by IR radiation (for example, of a CO2 lasers) or inductive heat coupling via the surrounding flange, inter alia. 
     Furthermore, the present invention includes the use of the feedthrough according to the present invention, with soft soldering on the terminal pin being executed using a reflow method. In addition, exterior soft soldering can be executed using a reflow method simultaneously with the interior soft soldering. 
     Preferred refinements of the terminal electrode feedthrough are disclosed, whose features, details, and advantages will become clear from the following description of the exemplary embodiment on the basis of the appended drawing. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a spatial illustration of a feedthrough according to the present invention having ten terminal pins for implant signals and having an eleventh terminal pin for the electrical ground connection. 
         FIG. 2  shows a sectional illustration of a further embodiment of the feedthrough according to the present invention. 
         FIG. 3  shows a sectional illustration of a variant of the feedthrough according to the present invention from  FIG. 2  having four nailhead-shaped terminal pins for implant signals and one nailhead-shaped ground pin. 
         FIG. 4  shows a sectional illustration of a further variant of the feedthrough according to the present invention having five terminal pins, which are provided with a coating (pre-tinning) which improves the reflow soft soldering. 
         FIG. 5  shows a sectional illustration of the additional variants of the feedthrough according to the present invention from  FIG. 2  having five terminal pins, one feedthrough bushing leading at least two terminal electrodes and the terminal pins being provided with a coating which improves the soft soldering capability. 
         FIG. 6  shows a sectional illustration of an alternative embodiment of the feedthrough according to the present invention having five terminal electrodes and having components soldered using glass. 
         FIG. 7  shows a sectional illustration of a further embodiment of the feedthrough according to the present invention having a filter capacitor. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  generally shows an electrical feedthrough in a spatial illustration of a fundamental construction of a series feedthrough  102  having a view of the inner side (protruding into the implant interior) and the outer side. The electrical feedthrough includes a flange  101 , which preferably consists of, but is not limited to, Ti, Nb, Ta, Zr, alloys made of one or more of the elements, or further additive elements such as, but not limited to, Hf, Al, Fe, P, Si, Mn, or C, or ceramic, in which multiple feedthrough bushings  106  are located, to which terminal pins  103  are connected by soldered connections. An attachment  111 , which can be soft soldered, of the terminal pin  103  in the form of a disk can be recognized on the inner view, which is electrically and mechanically attached to the terminal pin  103  by a joint  112 . The components identified therein are described further in  FIG. 2 . The feedthrough is constructed in this and the following figures as a series feedthrough having a series made of ten feedthrough bushings  106  and terminal pins  103  and series having four or six such feedthrough bushings and terminal pins. A ground pin  114 , which also has an attachment  11  which can be soft soldered, is located in the latter. However, any number of feedthrough bushings and terminal pins may be implemented without departing from the spirit and scope of the present invention. 
       FIG. 2  shows the section of a further embodiment of the electrical feedthrough  202 . Identical or similar components are identified using reference numerals based on  FIG. 1 , but in the two-hundred series of numbers, and are not explained once again here. For example, the reference numeral  102  in  FIG. 1  identifies the same component as the reference numeral  202  in  FIG. 2 . 
     The flange  201  preferably guides at least one cylindrical feedthrough bushing  206  made, for example, of biocompatible Al2O3 in its flange openings  207 . Each of the bushings is soldered using a soldered connection  208  made, for example, of biocompatible, metal hard solder to the flange  201 . The feedthrough bushings  206  are provided in this embodiment with a metal coating in the area of the flange openings  207 , preferably a biocompatible coating made of niobium, in order to make them wettable by the hard solder and thus allow soldering. In the variant shown here, the ceramic feedthrough bushings  206  protrude beyond the flange  201  on both sides and ensure sufficiently long electrical insulation sections for high-voltage applications of the feedthrough  202 . 
     The terminal pin  203  preferably has a simple cylindrical shape, an outer end  204  and an inner end  205 , and is connected using a soldered connection  209  to the feedthrough bushing  206  and is thus fixed together with the feedthrough bushing in the flange  201 . Both of the soldered connections  208  and  209  are implemented in the production phase as soldered rings, which are located between the flange  201  and the feedthrough bushings  206  and/or between feedthrough bushings  206  and terminal pins  203 . These rings are liquefied by heating, for example, via electrical resistance heating, electrical induction, heat conduction, or infrared radiation, and form a biocompatible, mechanically stable, hermetically sealed soldered connection which can be loaded with alternating temperatures after cooling. 
     An attachment  211  which can be soft soldered, preferably in the form of nickel discs, is attached via a joint  212  on the inner end  205 . To be able to produce the listed soldered connections  208 ,  209 , and joints  212  cost-effectively in the same process, the materials of the soldered connections and the joint preferably include the same soldering material, such as, for example, gold solders, gold-niobium, gold-tantalum, gold-titanium, or gold-zirconium alloys. Alternatively, for example, copper, silver, copper-nickel, copper-zinc, copper-tin, silver-copper, silver-copper-zinc, silver-copper-zinc-tin, silver-copper-tin, silver-copper-zinc-cadmium, copper-phosphorous, copper-phosphorous-silver, or copper-gold alloys or numerous further alloys may be used in order to compensate for temperature inhomogeneities during the brazing process. These joints lying on the implant interior do not have to be implemented as biocompatible like the terminal pins lying on the implant interior, because they are separated from the outer side by the hermetically sealed implant housing and the hermetically sealed feedthrough. 
     As the preferred material combination, niobium is selected for the terminal pin  203  or  214 , nickel for the attachment  211  which can be soft soldered, and refined gold for the hard solder  212  or  215 , because refined gold generates soldered connections with both niobium and also with nickel which are miscible with one another in any alloy ratio and always form ductile phases. The resulting brazed connections are sufficiently stable that upon mechanical strain, the terminal pins  203  or  214  tear or fail in most cases, and not the brazed connections  212 . 
     Alternatively, however, it is also advantageous for processing technology to join the joint  212  between terminal pin  203  and attachment  211  using a hard solder having a higher melting point or to weld them directly without an additive in a first method step, in order to subsequently solder them in a second brazing process to the other components of the feedthrough  202 , so that possible problems—for example, in the case of complex and/or more spacious structures—with undesired temperature inhomogeneities are avoided. It is essential that soft solder having a tin component is not used in the joint  212 , in order to avoid brittle phases, which have little mechanical carrying capacity, between gold and tin. 
     Furthermore, the electrical feedthrough according to the embodiment shown includes a ground pin  214 , for which the observations just made with respect to the soldered connections also apply. 
     The inner surfaces of the attachments  211  of the terminal pins  203  and the ground pin  214  are preferably all approximately located in a common plane and thus allow successful reflow soldering, but may also intentionally lie in different planes, if this is required by the adaptation to the corresponding substrate of the implant. 
     In the embodiment shown here, the flange  201  has a groove  217  for receiving the half shells of an implant housing (not shown). A lip  218  is simultaneously used as a welding protection during the laser welding of the flange  201  to the housing half shells of the implant. 
       FIG. 3  shows a further variant of the embodiments from  FIG. 1  and  FIG. 2 . As before, identical or similar components are identified using reference numerals based on  FIG. 2 , but in the three-hundred series of numbers, and are not explained once again here. The pins  303  have nailhead-like or plate-like attachments (also called “nailheads”)  310  on the inner end  305 . Better orientation of the attachments  311  which can be soft soldered is thus made easier and more precise common planarity is achieved. 
       FIG. 4  shows a further or additional variant to the previously described embodiments. Identical or similar components are identified using reference numerals based on the previously described figures, but in the four-hundred series of numbers, and are not explained once again here. Before the actual reflow process, the attachments  411 , which can be soft soldered on the terminal pins  403  and the ground pins  414 , are wetted at least on their front face with a coating or layer  430 , preferably made of soft solder Sn37Pb, for example, from Weidinger or Zevaton, with suitable fluxes being used as aids for good wetting of the front faces of the attachments  411 , preferably of the standardized type “Alpha 850-33”. However, other fluxes such as aqueous solutions or solutions containing hydrochloric acid which are made of zinc chloride/ammonium chloride, alcohol-based solutions with dimethyl amine hydrochloride, or aqueous solutions made of strong activated halogenides are also suitable. All of these fluxes offer the advantage that after the completed wetting of the attachments  411  with soft solder  430 , they can be removed again from the feedthrough in a simple cleaning method using aqueous solutions without residues and possible leakage paths in the feedthrough are not concealed by flux residues, so that the feedthroughs may be tested reliably for hermeticity using helium leak tests. 
     The soft soldering surface is additionally brought into a common plane by a separate method—for example, by thermal pretreatment or by grinding. In general, a better common flatness is achieved using the layers  430  made of soft solder than is possible using the attachments  411  alone, so that production-related irregularities of the attachments  411  which can be soft soldered are compensated for using the layer. Furthermore, the coating provides favorable conditions for a reflow soft soldering method, because it is no longer necessary to first achieve the most complete possible wetting of the attachments  411  with soft solder during the reflow soldering, because the surfaces of the attachments  411  are already nearly completely wetted with soft solder. The lateral surfaces of the disc-shaped attachments  411  may also be wetted by the soft solder layer  430 . Even if the joints  412  containing gold solder are also unintentionally wetted using soft solder containing tin, and Au—Sn brittle phases are formed in the transition zones, the Au—Sn brittle phases do not represent a disadvantage in this configuration, because the Au—Sn brittle phases do not assume a mechanical function, are not noticeably mechanically loaded, and have ductile coherence with the remainder of the soft solder layer  430 , so that no components or particles of the soft solder  430  detach in the further application of the feedthrough. The inner ends  405  of the terminal pin  403  or the ground pin  414  may also be nailhead-shaped, as shown in  FIG. 3 . 
     It is advantageous for the method technology if both the feedthrough bushings  406  and also the inner walls of the openings  407  of the flange  401  have corresponding bevels or steps  428  and  429 . A tapered bushing outer surface  426  is thus formed, which generally protrudes further out of the flange  401  than without tapering, in order to ensure a sufficient installation section. Using this configuration, the ceramic can be centered in the inner cavity of the flange before the preparation of the soldered connection  408  and does not have to be held in position by additional aids. 
       FIG. 5  shows a further variant compatible with the prior embodiments, in which two or more pins  503  are soldered into a common ceramic  506 . Identical or similar components are identified using reference numerals based on the previously described figures, but in the five-hundred series of numbers, and are not explained once again here. The common ceramics  506  may have depressions or so-called “slots”  535 , which lengthen the electrical insulation sections between the pins  503  among one another and/or the pins  503  and the flange  501 , and thus increase the high-voltage stability of the feedthrough. In this embodiment, the attachments  511 , which can be soft soldered are provided with a coating  530  which can be soft soldered particularly well, for example, made of palladium, silver, gold, copper, or alloys of these materials. Gold coatings having thicknesses of up to approximately 200 μm are particularly preferred, because they do not form brittle phases with the tin of the soft solder at these layer thicknesses. The coated attachments  511  are preferably stamped out of nickel plates or films which are coated on both sides and are therefore preferably only provided on one front face with coatings  530  which can be soft soldered particularly well for the subsequent reflow process. The coating  530  and the other coating pointing toward the pin, at which the joint  512  is located, may include different materials and have different thicknesses, the other coating pointing toward the pin being particularly suitable for the hard soldering with the terminal pins  503  and the ground pin  514 , and the other coating  530  being particularly suitable for the reflow soft soldering. The attachments  511  may also additionally have coatings on their lateral surfaces which can be soft soldered particularly well, which ensures improved mechanical carrying capacity of the soft solder connections produced during the reflow soft soldering in this case. 
     In this variant, the flange  501  has a fitting  537 , which is used for welding into an opening of the implant housing (not shown). A stop or a lip  518  is simultaneously used as a welding protection during the laser welding of the flange  501  to the housing or the housing half shells of the implant. 
     A special embodiment is shown in  FIG. 6 . Identical or similar components are identified using reference numerals based on the previously described figures, but in the six-hundred series of numbers, and are not explained once again here. An inner feedthrough bushing  606  and an outer feedthrough bushing  636  are attached in each inner opening  607  of the flange  601 , which form a cavity with the flange  601 . The terminal pins  603  are soldered using a preferably biocompatible glass solder  609  to the flange  601  and the feedthrough bushings  606  and  636 , the glass solder also being located in the cavity and completely or nearly completely filling it. The feedthrough bushings  606  and  636  form a flow barrier for the glass solder  609  during the soldering, i.e., they prevent the glass solder  609  from flowing away out of the opening  607  of the flange  601  during the soldering process. Upon selection of the correct glass solder  609 , preferably glass solder of the type 8625 from Schott, the ground pin  614  can be soldered using hard solder  613  in the opening  619  of the flange  601 , and also the attachments  611  can be soldered using the joint  612 , because glass solder generally allows a wide temperature range of the processing, in the same soldering and/or heating process. In the case of a glass/ceramic feedthrough, the soldered connection  609  preferably includes a biocompatible glass solder, which simultaneously wets the flange  601 , the terminal pins  603 , and the feedthrough bushings  606  and  636  and whose coefficient of thermal expansion is preferably adapted to the wetted components. 
     In further variants, the feedthrough bushings  606  and/or  636  may optionally be left out simultaneously, if suitable materials or material combinations are selected for the flange, the terminal pins, and the glass solder for this purpose. In such cases, for example, the glass solder is adjusted in its composition so it is less oxidizing or even reducing, so that the metal surfaces are less attractive to the glass solder, the surface tension of the glass solder dominates in the brazing, and finally the glass does not flow out of the openings  607  during the processing in spite of low viscosity. These variants have the advantage that the soldered connections may be executed in a more space-saving manner overall than using two feedthrough bushings simultaneously. In further variants, the openings  607  may have bevels or steps, which form a positioning aid for the glass solder in the openings  607 . 
       FIG. 7  shows a further embodiment of the invention. Identical or similar components are identified using reference numerals based on the previously described figures, but in the seven-hundred series of numbers, and are not explained once again here. A filtered feedthrough  702  having a flange  701  is shown in  FIG. 7 , which has an inner feedthrough bushing  706 , an outer feedthrough bushing  736 , and a glass solder plug  709  lying between them. A terminal pin, which is implemented in two parts and fixed by the glass solder plug  709 , is shown in each of these feedthrough bushings  706  and  736 . It includes an outer biocompatible section  703 , on which a pin  711 , which can be soft soldered, is attached at a joint  712 . The solder material of the joint  712  can be one of the above-mentioned solder materials. The joint  712  can have been fixed during the production method by the glass solder plug so that it is located inside the inner feedthrough bushing  706 , in order to thus be protected against mechanical and chemical influences. Furthermore, the electrical feedthrough comprises a ground pin  714 , which is electrically and mechanically connected in this embodiment variant to the flange  701  using a spot weld  751 . The ground pin  714  can include the same biocompatible material as the biocompatible section  703  of the terminal pin, or also the same material in which the flange  701  includes, which can improve the welding capability, but includes a section  716  which can be soft soldered in the form of a disc. Both the pins  711  which can be soft soldered and also the section  714  of the ground pin which can be soft soldered may be provided with a soft solder coating  730  for better attachment and form a nearly common plane (“common zone”) for the reflow process by a special thermal method or by grinding. 
     For electromagnetic filtering, in this variant a filter capacitor  757  is used, which is held on the flange using a bushing  753 . The bushing  753  is electrically and mechanically attached on the flange  701  using one or more spot welds or weld seams  751 , with the flange  701  being able to have a depression for better positioning of the bushing  753  in relation to the flange  701 . The spot welds  751  are applied so that a leak test connection is provided between the bushing  753  and the flange  701 . 
     The filter capacitor  757  includes laminar electrodes  756  and  758 , which are embedded in a dielectric material  757 , which includes barium titanate, for example. The electrodes  756  have a metal plating  755  which can be soft soldered on the outer side of the capacitor, made of palladium, silver, copper, or their alloys, for example. An electrical and mechanical ground connection is performed on this metal plating via a fixed soldered connection  754  to the bushing  753  fastened on the flange  701 . The electrodes  758  are also provided with a metal plating  765  which can be soft soldered, also made of palladium, silver, copper, or their alloys, at the openings of the capacitor, through which the pins  711 , which can be soft soldered, extend and using which the soldered connection  764  is soldered to the pins  711  which can be soft soldered, in order to form the electrical connections to the electrical signals of the electrical implant. For reasons of better manufacturing, the soldered connections  764  and  754  may include various soft solders having different melting points or ranges. A material composition is preferably selected as the material for the soldered connection  754 , for example, PbSn3.5Ag1.5, which has a higher processing temperature at a soldering range of 305° C. than the material of the soldered connection  764  having the preferred material composition of, for example, PbSn5Ag2.5 and a soldering temperature of 280° C. Thus, in a preferred production method, the capacitor  757  can first be soldered onto the bushing  753 , which can be soft soldered using the higher-melting-point soft solder  754 , the bushing  753  having the soldered-on capacitor  757  can be pushed over the pins  711  and electrically and mechanically attached on the flange  701  using welds  750 , then finally can be soldered onto the pins  711  which can be soft soldered using a lower-melting-point soft solder  764 , without the higher-melting-point soft solder  754  running the danger of melting again during the second soft soldering using the soft solder  764  and detaching from the metal plating  755  and losing the electrical/mechanical connection to the capacitor electrodes  756 . The electrical feedthrough thus produced can be tested for hermeticity between the inner and outer sides of the implant using a helium leak test, because the leak test connection provides a passage to the cavity  752 , which is delimited by the flange  701 , bushing  753 , capacitor  757 , and the individual inner feedthrough bushings  706  and pins  711  which can be soft soldered, through which the helium can flow. 
     In further variants of this embodiment, instead of a single capacitor  757 , multiple independent capacitors may also be used. It is also possible to only filter individual terminal pins using capacitors  757  (for example, for an antenna attachment for wireless transmission of signals out of the implant). The electrical and mechanical attachment of the capacitor  757  can also be implemented using electrically conductive adhesives, using, for example, welding, clamps, or plugs, special value always being placed on the leak test capability of the configuration. The leak test capability can alternatively or additionally be implemented by additional openings (not shown) in the capacitor  757 , in the solders  754  and  764 , and/or in the bushing  753 . The flange  701  can alternatively be shaped so that instead of the bushing  753 , the flange continues at a similar point and receives the capacitor  757  and has an additional opening for the leak test capability in the wall thus resulting (not shown here) to the cavity  752 . 
     In all of the described embodiments, joining technologies and forms other than those listed may also be used, for example, by welding, clamping, electrically conductive gluing, bonding, and the like. 
     In further variants, the pins  711  may also be attached to the flange  701  and filtered using the examples offered in  FIGS. 2-5 . 
     In further reasonable variants, all combinations and geometric modifications from  FIGS. 1-7  may be implemented and are part of this patent application. 
     It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teachings of the disclosure. The disclosed examples and embodiments are presented for purposes of illustration only. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof. Additionally, the disclosure of a range of values is a disclosure of every numerical value within that range. 
     
       
         
               
             
               
               
             
           
               
                   
               
               
                 List of reference numerals: 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 101, 201, 301, 401, 501, 601, 701 
                 flange 
               
               
                 102, 202, 302, 402, 502, 602, 702 
                 feedthrough 
               
               
                 103, 203, 303, 403, 503, 603, 703 
                 terminal pin 
               
               
                 104, 204, 304, 404, 504, 604, 704 
                 outer, biocompatible end of the  
               
               
                   
                 terminal pin 
               
               
                 105, 205, 305, 405, 505, 605, 705 
                 inner end of the terminal pin 
               
               
                 106, 206, 306, 406, 506, 606, 706 
                 feedthrough bushing, inner  
               
               
                   
                 feedthrough bushing 
               
               
                 207, 307, 407, 507, 607, 707 
                 opening in the flange 
               
               
                 108, 208, 308, 408, 508, 607, 708 
                 soldered connection between  
               
               
                   
                 flange and feedthrough bushing 
               
               
                 109, 209, 309, 409, 509, 609, 709 
                 soldered connection between  
               
               
                   
                 terminal electrode and feedthrough  
               
               
                   
                 bushing 
               
               
                 310, 410 
                 nailhead-like attachment on the  
               
               
                   
                 inner end of the terminal pin 
               
               
                 111, 211, 311, 411, 511, 611, 711 
                 attachment of the terminal pin  
               
               
                   
                 which can be soft soldered 
               
               
                 112, 212, 312, 412, 512, 612, 712 
                 joint between terminal pin and  
               
               
                   
                 attachment 
               
               
                 113, 213, 313, 413, 513, 613, 713 
                 soldered connection between  
               
               
                   
                 ground pin and flange 
               
               
                 114, 214, 314, 414, 514, 614, 714 
                 ground terminal pin or ground pin 
               
               
                 117, 217, 317, 417, 517, 617, 717 
                 groove in the flange for receiving  
               
               
                   
                 the implant housing halves 
               
               
                 118, 218, 318, 418, 518, 618, 718 
                 interior lip 
               
               
                 219, 319, 419, 519, 619 
                 opening to receive the ground pin 
               
               
                 428 
                 step in the flange 
               
               
                 429 
                 step in the feedthrough bushing 
               
               
                 430, 530, 630, 730 
                 soft solder (flattened on the end)  
               
               
                   
                 or coating which can be soft  
               
               
                   
                 soldered or layer which can be soft  
               
               
                   
                 soldered on the attachment 
               
               
                 535 
                 “slot” or depression in the  
               
               
                   
                 feedthrough bushing 506 to  
               
               
                   
                 enlarge the insulation section, e.g.,  
               
               
                   
                 between two pins 503 or between  
               
               
                   
                 one pin 503 and the flange 501 
               
               
                 636, 736 
                 outer feedthrough bushing 
               
               
                 537 
                 weld fitting in the flange 
               
               
                 751 
                 spot welds or weld seams 750 
               
               
                 752 
                 cavity 
               
               
                 753 
                 metal bushing which can be soft  
               
               
                   
                 soldered and welded 
               
               
                 754 
                 soldered connection between  
               
               
                   
                 bushing 753 and metal plating 
               
               
                   
                 755 of the capacitor 757 
               
               
                 755, 765 
                 metal plating of the capacitor 757 
               
               
                 756, 758 
                 capacitor electrode 
               
               
                 757 
                 ceramic dielectric material 
               
               
                 764 
                 soldered connection between pin  
               
               
                   
                 711 which can be soft soldered 
               
               
                   
                 and metal plating 765 of the  
               
               
                   
                 capacitor 757