Abstract:
An element ( 1 ) for mechanical and electrical coupling of a passive and/or active electrical unit ( 2 ) to an electrical circuit unit ( 3 ). The element ( 1 ) comprises at least one electrical contact element ( 10, 11 ) for electrical contacting of the passive and/or active electrical unit ( 2 ) with electrical circuit unit ( 3 ), a first side, which faces toward passive and/or active electrical unit ( 2 ), which comprises a second side ( 13 ), which faces toward electrical circuit unit ( 3 ), and at least one first means ( 14 ) for secure mechanical connection to the electrical circuit unit is attached fixed to second side ( 13 ). Also discloses an electromedical implant for stimulating human/animal organism and/or sensing human/animal physiological signals. Comprises at least one electrical circuit unit ( 3 ), at least one passive and/or active electrical unit ( 2 ), and at least one coupling element, to electrically and mechanically couple unit ( 2 ) and unit ( 3 ) together.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an element for mechanical and electrical coupling of a passive and/or active electrical unit to an electrical circuit unit. Such elements comprise at least one electrical contact element for the electrical contacting of the passive and/or active electrical unit with the electrical circuit unit and a first side facing toward the passive and/or active electrical unit. 
     2. Description of the Related Art 
     The connection of electrical components, such as active and/or passive electrical units, to electrical circuit units plays an especially important role in electrical engineering. In the following, electric or electronic circuits are referred to as electrical circuit units. While the assembly of electrical and/or electromechanical components (switches, lamps, motors . . . ) into a functioning configuration is referred to as an electrical circuit—the function of the circuit being produced by the electrical current which flows through the components in a closed loop (electric circuit), the assembly of electrical and particularly electronic components (such as diodes and transistors) into a (functioning) configuration is referred to as an electronic circuit. An electronic circuit differs from an electrical circuit by the use of electronic components. 
     Electrical circuit units are located on circuit boards, for example. A circuit board, also referred to as a printed wiring board, printed circuit board, or etched wiring board (printed wiring board=PWB, printed circuit board=PCB, or etched wiring board=EWB), is used for the mechanical fastening and the electrical connection of electronic components. The connection lines are usually produced by etching from a thin layer of conductive material on an insulating base plate. The components are soldered onto these printed conductors. Circuit boards comprise insulating material which may also be flame retardant. Examples of such materials are phenol resin, epoxide resin, glass or glass fibers, Teflon, ceramics, LTCC, HTCC, or polyester. 
     A secure electrical connection is of great importance in electrical circuit units, to avoid short-circuits, loose contacts, or other malfunctions. For this purpose, fixed electrical connections are important, which are typically made possible by electrically conductive soldering, welding, and/or bonding processes. In such processes, electrically conductive elements of such electrical circuit units are connected to components and/or multiple electrical circuit units are connected to one another to produce entire networks of different circuits. Individual components are also assembled into electrical circuit units by such processes. 
     Surface-mounting technology (English surface-mounting technology, abbreviated SMT) has developed into the most important method which is most favorable for processing technology in this case. Surface-mounted components (English surface-mounted device, abbreviated SMD or SMD components) are soldered directly on to the circuit board (printed circuit board) using solderable terminal surfaces. This processing is therefore also called assembling, although the assembling also comprises other work steps besides only placing the components on the circuit board. This assembly comprises at least the following steps:
         application of soldering paste (a mixture of metal beads (for example: tin beads) and flux) or adhesive to the circuit board   assembling the components   soldering the circuit board or curing the adhesive       

     A secure connection of components to electrical circuit units is especially important in medical implants, because implants must operate reliably and may not be maintained or explanted easily. An implant is an artificial material implanted in the body, which is to remain therein permanently or at least for a long period of time. Implants for stimulating the human or animal organism and/or sensing human or animal physiological signals are viewed as electromedical implants in the meaning of the present invention. For example, these are cardiac pacemakers, implantable defibrillators, cardioverters, neurostimulators, or brain pacemakers and artificial hearts. Electromedical implants contain at least one electrical circuit unit, which is capable of analyzing sensed human or animal signals, generating electrical stimulation pulses, storing data from the sensed signals and the stimulation pulses, and/or transmitting the data from the sensed signals and the stimulation pulses out of the body, and at least one passive or active electrical unit. 
     In such electromedical implants the communication out of the body is—for the above-mentioned reasons of the maintenance or even the programming and/or transmission of physiological states and signals or technical data of the implant—of predominant significance. Such an implant may only be externally programmed by these apparatuses and tailored to the patient and the quality of life may thus be increased. The transmission of data of the implant and threatening or notable states of the body to a treating physician is also important. Only in this way may the physician ensure optimum treatment. For this reason, the above-mentioned electromedical implants have communication means, which allow wireless communication, almost as standard equipment as one of the passive and/or active electrical units. For example, such communication means comprise antennas for near-field or far-field telemetry, which may be coils of any type, above all air-core coils, for example. 
     Such passive and/or active electrical units may additionally or alternatively comprise one or more of the following components, for example:
         capacitors,   batteries and/or accumulators   one or more further electrical circuit units, which are capable of analyzing sensed human or animal signals, generating electrical stimulation pulses, storing data from the sensed signals and the stimulation pulses, and/or transmitting the data from the sensed signals and the stimulation pulses out of the body,   active and/or passive storage units   filtered or unfiltered feedthroughs       

     Placing passive and/or active electrical units using so-called mounting frames in a housing is known. However, these frames are only used for the defined positioning of the units in this housing and do not offer any further possibilities for electrical and/or mechanical coupling to one another. 
     Furthermore, providing coils as communication units in electromedical implants, which are welded into laminates—i.e. into plastic films—is known. Two electrical terminal strips are led out of the films, which are electrically contacted manually with an electrical circuit unit via corresponding electrical contacts, in that they are mechanically soldered on manually. This film is connected to the circuit via a gluing method, for example, to thus protect the relatively sensitive terminal strips from being torn off. The disadvantage of this solution is that the production may not be automated, because the laminates may be damaged during SMT processes, for example. The terminal strips are also not or not easily electrically connectable to the circuit via automated processes. In addition, very many work steps having greatly varying parameters are required for the production, because of which the production processes are very time-consuming, work intensive, and thus costly. The electromedical implants cited in this approach are known, for example, from U.S. Pat. No. 4,441,498. 
     An improvement of the cited solution is presented in WO 2004/039450. A frame element made of a solid plastic material is situated around the communication coil. The terminal strips of the communication coil are electrically contacted and mechanically fastened to contact elements, which are located on the frame element, the contact elements being situated on the outer edge of the frame element in such a way that they also allow an electrical contact to glass-ceramic bushings. The electrical contacting between the communication coil and the electrical circuit unit occurs via a soldering process, in that the contact elements of the frame element are soldered to the circuit. The disadvantage of this solution is that there is only a punctual mechanical fastening between the electrical circuit unit and the frame element having the communication coil, which may easily result in damage and/or tearing off of the contacting in the event of shocks of the electromedical implants. To remove this disadvantage, it has already been described in WO 2004/039450 that in a further work step, planar gluing of the frame element and the communication unit located therein to both the electrical circuit unit and also to a half-shell of the hermetically sealed housing occurs. However, this solution conceals the disadvantage that again an additional work step must be performed, which may not be automated and even requires the application of a further joining technology. The connection to the hermetically sealed housing conceals additional disadvantages, whose solution is not the object of the present invention, however. 
     BRIEF SUMMARY OF THE INVENTION 
     Starting from the disadvantages of the prior art, the present invention is based on the object of ensuring the secure, cost-effective electrical and mechanical contacting, which is extensively producible completely automatically and easily, of a passive and/or active electrical unit to an electrical circuit unit, which may be extensively prepared cost-effectively and completely automatically and withstands shocks in the scope of the physically possible. 
     This object is achieved as claimed herein, in that the element from the preamble comprises a second side, which faces toward the electrical circuit unit, at least one first means for secure mechanical connection to the electrical circuit unit being attached fixed on this second side. 
     Is important for the observation and understanding of the further embodiment that a mechanical connection has no electrical connection or effect. A mechanical connection in the meaning of the present invention thus has no electrical conduction properties and is to be viewed as an infinite electrical resistor. 
     This solution has the advantage that in addition to the mechanical coupling, which occurs due to the fixed electrical contacting with the electrical contact element, at least one further mechanical coupling results between the passive and/or active electrical unit and the electrical circuit unit. Secure redundant electrical and mechanical contacting and thus an error-free interaction of the passive and/or active electrical unit and electrical circuit unit are thus made possible. In addition, the extensive security of the contacts from shocks or continuous periodic or rhythmic strains is advantageous. 
     Furthermore, the present invention offers the advantage that pre-mounting of the passive and/or active electrical unit with the coupling element according to the present invention may be performed, so that simple cost-effective and completely automatic process designs are made possible. 
     An outer delimitation edge preferably delimits the first and second sides of the element in their extension, which also preferably corresponds to the external contour of an outer delimitation edge of the electrical circuit unit. 
     This further secures the coupling of passive and/or active electrical unit and electrical circuit unit, because it is thus ensured that in the event of an impact, for example, no edges project or differing forces arise on both units. 
     In an additional embodiment, an inner delimitation edge delimits the first and second sides of the element in their extension. In a preferred type of the additional embodiment, the inner contour corresponds to an inner delimitation edge of the passive and/or active electrical unit. 
     In an additional preferred embodiment, the outer and inner delimitation edges run largely parallel and thus form a frame. This results in a savings in material and thus a reduction in weight. Furthermore, such a frame increases the stability of the passive and/or active electrical unit. 
     In general, the first and second sides of the element may be largely planar surfaces facing away from one another. This improves and simplifies the secure mounting of the passive and/or active electrical unit and the electrical circuit unit and reduces the size of the mounted units. 
     The at least one contact means of the element for electrical contacting of the passive and/or active electrical unit with the electrical circuit unit may comprise a first and a second end. The first end is used for the electrical contacting with the passive and/or active electrical unit and the second end is used for the electrical contacting with the electrical circuit unit. 
     The at least one contact means preferably comprises terminal surfaces capable of soldering, bonding, welding, or gluing using an electrically conductive adhesive, which preferably produce a soldered electrical connection between the passive and/or active electrical unit and the electrical circuit unit using a surface-mounting technology (SMT). 
     The terminal surfaces may also be designed as capable of bonding or welding. It is also possible to set up the terminal surfaces in such a way that a connection using electrically conductive adhesives is made possible. 
     In a further preferred design, the at least one contact means is located on the second side. The electrical contacts of the passive and/or active electrical unit are brought through at least one opening in the element from the first side to the second side of the element for the electrical contacting. 
     The cited features simplify the automated mounting of the element according to the present invention with the passive and/or active electrical unit and the electrical circuit unit in as few mounting/process levels as possible. Predefined mounting surfaces are provided, which allow the concrete application of surface-mounting technologies (SMT), which results in simple automation of the mounting. 
     In a further design, the at least one further means comprises surfaces which are capable of soldering, bonding, welding, or gluing using electrically conductive adhesive. A soldered mechanical connection may preferably be produced between the element according to the present invention and the electrical circuit unit using a surface-mounting technology (SMT) via these surfaces. 
     This at least one first means is advantageously used for the further secure fastening of the passive and/or active electrical unit to the electrical circuit unit and prevents fastening from only occurring punctually by the electrical contacting at the electrical contacts. Furthermore, the construction allows the simultaneous electrical contacting of the passive and/or active electrical unit with the electrical circuit unit at the electrical contacts and the mechanical connection at the at least one first means for secure mechanical connection by only one process step, for example, an SMT process, which allows extensive automation of the mounting. 
     In addition, in a further embodiment, a second means may be provided for the secure mechanical fastening of the passive and/or active electrical unit. The second means is electrically and mechanically independent from the first means for the secure mechanical connection to the electrical circuit unit and fastens the passive and/or active electrical unit at the element according to the present invention. The second means preferably comprises dispensed adhesive. Exemplary used is an adhesive with the trademark “Tra-Con Ablebond 400-5” compounded by Tra-Con, Inc. It contributes to further ensuring the electrical contacts between passive and/or active electrical unit and electrical circuit. 
     Moreover, the element preferably comprises an electrically insulating material, preferably flame retardant materials, especially preferably one of the following materials: phenol resin, epoxide resin, glass or glass fibers, Teflon, ceramics, LTCC, HTTC, or polyester. 
     The passive and/or active electrical unit is preferably a communication unit, which also allows wireless communication. The communication unit preferably comprises an antenna for near-field or far-field telemetry, especially preferably a coil and more preferably an air-core coil. 
     Because the use of the element according to the present invention in an electromedical implant is very probable, the present invention is also based on the object of solving the disadvantages of the prior art in regard to electromedical implant, in that more secure operation and secure communication between the extracorporeal area and the electromedical implant are to be ensured. 
     This object is achieved by as claimed herein, in that, in an electromedical implant, at least one element according to the present invention couples a passive and/or active electrical unit electrically and mechanically to an electrical circuit unit. 
     For further protection from mechanical strains or damage, the implant also comprises a support frame having struts which enclose the passive and/or active electrical unit on three sides. The support frame is produced from temperature-resistant plastic, preferably from liquid crystal polymer. One example of such polymer and which is exemplarly used is known under trade name Ticona Vectra® T130 LCP. 
     In a further preferred design, the implant also provides a dispensed adhesive or a adhesive strip for the secure mechanical fastening of the support frame to the passive and/or active electrical unit, the dispensed adhesive or a adhesive strip preferably being electrically insulating, especially preferably comprising an electrically insulating adhesive strip. Exemplary used is an adhesive with the trademark “Tra-Con Ablebond 400-5” compounded by Tra-Con Inc. 
     Furthermore, the implant comprises a hermetically sealed housing, which encloses the units and means, the housing preferably comprising biocompatible material, especially preferably plastic, medical stainless steel, titanium, or ceramics, and/or alloys made of these materials. 
     The passive and/or active electrical unit in this implant according to the present invention is preferably a communication unit, which also allows wireless communication. The communication unit preferably comprises an antenna for near-field or far-field telemetry, especially preferably a coil and more preferably an air-core coil. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following, the present invention is described on the basis of an exemplary embodiment having a passive electrical unit in the form of an air-core coil. 
         FIG. 1 : shows a coupling element according to the present invention in a top view of the second side 
         FIG. 2 : shows a coupling element according to the present invention in a top view of the second side having pre-mounted air-core coil 
         FIG. 3 : shows a coupling element according to the present invention in a perspective view having a protective element 
         FIG. 4 : shows an exploded drawing of a complete construction 
         FIG. 5 : shows an exploded drawing of the internal construction of an implant according to the present invention having an assembly made of electrical circuit unit, coupling element, and air-core coil 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The coupling element  1  according to the present invention is shown in  FIG. 1  in a view toward the second side  13 . The second side is facing toward an electrical circuit unit  3  illustrated in  FIG. 4 . The coupling element comprises an electrically insulating material, preferably flame retardant materials such as: phenol resin, epoxide resin, glass or glass fibers, Teflon, ceramics, LTCC, HTTC, or polyester. 
     Two electrical contact elements  10  and  11  are used for the electrical contacting of an air-core coil  2  (also shown in  FIG. 4 ) with the electrical circuit unit  3 . The contact elements are only located on the second side  13  and may be attached both connected fixed and also displaceably to the element  1  according to the present invention. If the contact elements  10  and  11  are connected fixed, they have a three-dimensional cuboid shape, five sides being enclosed by the insulating material and a fixed connection thus being produced. However, plates or coatings may also be used. 
     The exposed surface of the contact elements  10  and  11  is designed as a solderable terminal surface and composed in such a way that a solder contact may be produced using SMT processes. 
     Furthermore, multiple means  14  for the secure mechanical connection to the electrical circuit unit  3  are attached fixed to the second side  13  of the exemplary embodiment. These means  14  are connected fixed to the element  1 . The means have an external surface, which, like the contact elements  10  and  11 , are also designed as solderable and composed in such a way that a solder contact may be produced using SMT processes. 
     Thus, in one work step using SMT processes, both an electrical contact and also a mechanical connection may be produced between an electrical circuit unit  3  and the element according to the present invention. 
       FIG. 2  again shows the second side  13  of the element  1  according to the present invention. On a first side (not visible), which forms a surface facing away from the second side, an air-core coil  2  is attached fixed in a pre-mounting step. The second side comprises no surfaces which may be assembled using SMT processes in this exemplary embodiment. Air-core coil  2  is connected fixed in a nonconductive way to the contact element by way of dispensing adhesive at the contacting surfaces between the element  1  and the air-core coil  2 . Exemplary used is an adhesive with the trademark “Tra-Con Ablebond 400-5” compounded by Tra-Con Inc. As is recognizable from  FIG. 4 , the air-core coil  2  also may be connected fixed to the element according to the present invention by using second means for securely mechanical connection of air-core coil  18 . In this case this means is a double-sided adhesive film. 
     The double-sided adhesive film is attached to the element  1  in such a way that the two openings  18   a  and  18   b  of the film  18  come to rest congruently to the openings  17   a  and  17   b  of the element  1 . A continuous opening thus arises, so that the contact strips  21   a  and  21   b  of the air-core coil  2 , which could be simply the contrary ends of the coil wire unspooled from the main winding of air-core coil  2  for electrical termination, may be led through the openings  17   a  and  17   b  to the solderable terminal surfaces of the contact elements  10  and  11 , which are attached on the second side  13  facing away from the coil. 
     The solderable terminal surfaces of the electrical contact elements  10  and  11  have a rectangular shape in this exemplary embodiment, so that they each have a first end  10   a  and  11   a  and a second end  10   b  and  11   b . In a further pre-mounting step, at the first end  10   a  and  11   a , the contact strips  21   a  and  21   b  of the air-core coil  2  are soldered for example via an SMT process, preferably an automated SMT process, only to the first end  10   a  and  11   a  and electrically connected to the solderable terminal surfaces of the electrical contact elements  10  and  11 . The air-core coil  2  and the element  1  according to the present invention now form a pre-mounted assembly, which may now be extensively electrically tested. 
     This SMT process—also referred to as assembly—for pre-mounting comprises at least the following steps:
     I. Applying soldering paste (a mixture of metal beads (for example: tin beads) and flux) or adhesive to the circuit board on the first ends  10   a  and  10   b      II. Placing the contact strips  21   a  and  21   b  only on the ends  10   a  and  11   a      III. Attaching the contact strips  21   a  and  21   b  only to the ends  10   a  and  11   a  by soldering, welding (for example spot welding), gluing with electrically conductive adhesive,   

     In the final manufacturing step, in a processing step using a further SMT process, the mechanical coupling and the electrical contacting are performed in that, only at the second ends  10   b  and  11   b  of the electrical contact elements  10  and  11  and at the first means  14 , the pre-mounted assembly made of element  1  and air-core coil  2  is connected fixed to the electrical circuit unit  3 . 
     This SMT process for final mounting comprises at least the following steps:
     I. Applying soldering paste (a mixture of metal beads (for example: tin beads) and flux) or adhesive to the circuit board on the ends  10   b ,  11   b , and the means  14     II. Placing electrical contacts of the electrical circuit unit  3  on the ends  10   b  and  11   b      III. Soldering the electrical contacts of the electrical circuit unit only to the ends  10   b  and  11   b      

     As a further protection of the pre-mounted soldered points, at which the contact strips  21   a  and  21   b  are electrically connected to the first ends  10   a  and  11   a  of the terminal surfaces of the electrical contact elements  10  and  11 , a protective cap is additionally provided. This protective cap is shown in  FIG. 3  by the reference numeral  6 . The protective cap  6  covers the first ends  10   a  and  11   a  of the terminal surfaces of the electrical contact surfaces  10  and  11 , the contact strips  21   a  and  21   b , and the openings  17   a  and  17   b . The pre-mounted soldered points may thus not be damaged during the final mounting process. In a further embodiment the protective cap is currently a second type of adhesive, also dispensed only over the first ends  10   a  and  11   a . Exemplarly it could be used an adhesive, known under trade name Hysol 0151. 
       FIG. 4  shows an exploded drawing of a complete construction made of the coupling element  1  according to the present invention, which is located between an air-core coil  2  and an electrical circuit unit  3 . The element  1  is connected fixed in the assembled state to both the air-core coil  2  and the electrical circuit unit  3 . As is obvious from the figure, an outer delimitation edge  15  of the element  1  is visible, which is tailored to the outer contour of the electrical circuit unit  3 . The air-core coil or also alternately any other passive and/or active unit  2  is advantageously also the outer contour of the electrical circuit unit  3 , because this increases the packing density. 
     It is also obvious from  FIG. 4  that the element  1  has an inner delimitation edge  16 , which corresponds to an inner delimitation edge of the air-core coil  2 . A frame advantageously arises in this exemplary embodiment, because, as is typical in an air-core coil, the inner contour runs parallel to the outer contour. In this case, the inner contour of the air-core coil  2  and of the element  1  runs parallel to the outer contour of the circuit  3 . The opening which is defined by the inner delimitation edge is used for saving material and thus for reducing weight. This is of eminent importance in electromedical implants above all. 
       FIG. 5  shows an exemplary internal construction of an implant according to the present invention. Such an implant has a hermetically sealed titanium housing (not shown here), in which, inter alia, the illustrated components are integrated. A coupling element  1  is securely mechanically and electrically connected via electrical contact elements  10  and  11 , which may be processed by SMT, and via at least one means  14  for mechanical coupling to an electrical circuit unit  3  (not shown here). An air-core coil  2  is securely mechanically connected on the side of the coupling element  1  opposite to the electrical circuit unit using dispensing adhesive or a second means  18 . The electrical contact between the air-core coil  2  and the electrical coupling elements  10  and  11  is produced via the contact strips  21   a  and  21   b . The “contact strips” could also be simply the contrary ends of coil wire, unspooled from the main winding, for electrical termination. 
     The coil must be suitably protected due to the continuous rhythmic and arrhythmic shocks which an electromedical implant is subjected to in a body. For this reason, a support frame  4  is connected to the air-core coil  2  by way of dispensing adhesive at the contacting surfaces between the element  1  and the air-core coil  2 . Exemplary used is an adhesive with the trademark “Tra-Con Ablebond 400-5” compounded by Tra-Con Inc. It is also possible to connect fixed the support frame to the air-core coil  2  using a third mechanical means  5 . The third means  5  is produced from the same material from which the second means  18  is produced. As an further important function, support frame  4  protects the coil from damage during inner device assembly during manual or automatic assembly steps. 
     The support frame  4  encloses the coil in such a way that only the surface of the air-core coil  2  which is attached to the first side of the coupling element  1  is not protected. The air-core coil  2  is thus protected on all external sides in the assembled state. 
     To increase the stability, the support frame  4  has struts  41   a ,  41   b , and  41   c . In addition to stability, also a purpose of the three-strut structure of struts  41   a ,  41   b  and  41   c  is to present a round, flat surface for the complete assembled coil assembly to be picked up with a movable vacuum tip, and placed on the electrical circuit  3  by automated assembly equipment during the SMT process. 
     LIST OF REFERENCE NUMBERS 
     
         
           1  . . . Coupling element 
           2  . . . electrical unit, for example air-core coil 
           3  . . . electrical circuit unit 
           4  . . . support frame 
           5  . . . third mechanical means for securely mechanical connection of support frame 
           6  . . . protective cap 
           10  . . . electrical contact element 
           10   a  . . . first end of electrical contact element 
           10   b  . . . second end of electrical contact element 
           11  . . . electrical contact element 
           11   a  . . . first end of electrical contact element 
           11   b  . . . second end of electrical contact element 
           13  . . . second side of coupling element 
           14  . . . means for secure mechanical connection 
           15  . . . outer delimination edge of coupling element 
           16  . . . inner delimination edge of coupling element 
           17   a  . . . opening in coupling element 
           17   b  . . . opening in coupling element 
           18  . . . second means for securely mechanical connection of air-core coil 
           18   a  . . . opening in second means for securely mechanical connection of air-core coil 
           18   b  . . . opening in second means for securely mechanical connection of air-core coil 
           21   a  . . . contact strip of air-core coil 
           21   b  . . . contact strip of air-core coil 
           41   a  . . . strut of support frame 
           41   b  . . . strut of support frame 
           41   c  . . . strut of support frame