Co-fired hermetically sealed feedthrough with alumina substrate and platinum filled via for an active implantable medical device

Abstract

A co-fired hermetically sealed feedthrough is attachable to an active implantable medical device. The feedthrough comprises an alumina dielectric substrate comprising at least 96 or 99% alumina. A via hole is disposed through the alumina dielectric substrate from a body fluid side to a device side. A substantially closed pore, fritless and substantially pure platinum fill is disposed within the via hole forming a platinum filled via electrically conductive between the body fluid side and the device side. A hermetic seal is between the platinum fill and the alumina dielectric substrate, wherein the hermetic seal comprises a tortuous and mutually conformal interface between the alumina dielectric substrate and the platinum fill.

What is claimed is: 
     
       1. A hermetically sealed feedthrough that is attachable to an active implantable medical device (AIMD), the feedthrough comprising:
 a) an electrically conductive ferrule comprising a ferrule sidewall defining a ferrule opening extending to a ferrule body fluid end surface and to a ferrule device side end surface, wherein, when the ferrule is attached to an opening in a housing of an AIMD, the ferrule body fluid end surface and the ferrule device side end surface reside outside the AIMD and inside the AIMD, respectively; 
 b) an alumina substrate comprised of at least 96% alumina and having a thickness extending from to a substrate body fluid side and to a substrate device side, wherein the alumina substrate resides in the ferrule opening where the alumina substrate is hermetically sealed to the ferrule; 
 b) ac) an active via hole disposedextending through the alumina substrate fromto the substrate body fluid side and to the substrate device side, wherein a counter-bore in the substrate is aligned with the active via hole and has a depth that extends from the substrate body fluid side part-way into the substrate thickness; 
 c)d) a substantially closed pore and substantially pureclosed-pore platinum fill disposed withinthat is hermetically sealed to the alumina substrate in the active via hole and, the substantially closed-pore platinum extending betweento the counter-bore at the substrate body fluid side and to or adjacent to the substrate device side of the alumina substrate; and 
 d) a hermetic seal between the platinum fill and the alumina substrate, 
 e) an electrically conductive bond pad comprising a pad portion and a post, wherein the pad portion at least partially resides in the counter-bore on the substrate body fluid side with the post extending into the substantially closed-pore platinum in the active via hole, and 
 f) wherein the platinum fill forms a tortuous and mutually conformal knitline or interface between the alumina substrate and the platinum fill  pad portion of the bond pad has an uninterrupted upper surface of a width that is greater than a diameter of the via hole, and 
 g) wherein the combined length of the pad portion and the post of the bond pad is less than the substrate thickness. 
 
     
     
       2. The feedthrough of  claim 1 , wherein the alumina substrate comprises at least 99% alumina. 
     
     
       3. The feedthrough of  claim 1 , wherein there is a tortuous and mutually conformal knitline between the alumina substrate and the platinum fill and wherein the knitline comprises a glass that is at least about 60% silica. 
     
     
       4. The feedthrough of  claim 1 , wherein the hermetic seal has a leak rate at least no greater than 1×10 −7  std cc He/sec. 
     
     
       5. The feedthrough of  claim 1 , wherein an inherent shrink rate during a heat treatment of the alumina dielectric substrate in a substrate green state is greater than that of the substantially closed-pore platinum fill in the a platinum green state. 
     
     
       6. The feedthrough of  claim 1 , wherein the substantially closed-pore platinum fill is characterized as having been formed from a platinum paste that prior to bake out bake-out and sintering had a platinum metal content of at least 80%. 
     
     
       7. The feedthrough of  claim 1 , wherein the substantially closed-pore platinum fill is characterized as having been formed from a platinum paste that prior to bake out bake-out and sintering had a platinum metal content of about 95%. 
     
     
       8. The feedthrough of  claim 1 , wherein the substantially closed-pore platinum fill is characterized as having been packed into the active via hole prior to bake out bake-out and sintering to occupy at least 90% of the available space in the active via hole. 
     
     
       9. The feedthrough of  claim 1 , wherein the substantially closed-pore platinum fill is characterized as having been packed into the active via hole prior to bake out bake-out and sintering to occupy about 99% of the available space in the active via hole. 
     
     
       10. The feedthrough of  claim 1 , wherein, as a result of having been subjected to a bake-out and sintering, the alumina dielectric substrate is characterized as having shrunk from a substrate green state by about 20% to about 14% more than the substantially closed-pore platinum fill shrinks from a platinum green state as a result of having been subjected to bake out and sintering. 
     
     
       11. The feedthrough of  claim 1 , wherein, as a result of having been subjected to bake-out and sintering, the alumina dielectric substrate is characterized as having shrunk from a substrate green state by about 16% more than the substantially closed-pore platinum fill shrinks from a platinum green state as a result of having been subjected to bake out and sintering. 
     
     
       12. The feedthrough of  claim 1 , wherein a difference in a first coefficient of thermal expansion (CTE) of the alumina dielectric substrate and a second CTE of the substantially closed-pore platinum fill is from about 0.5×10 −6 /K to about 1.0×10 −6 /K. 
     
     
       13. The feedthrough of  claim 1 , wherein the platinum filled active via hole comprises a larger cross sectional cross-sectional area at either both a first active via end exposed to at the substrate body fluid side or and at a second active via end exposed to at the substrate device side as compared to a smaller cross sectional cross-sectional area of the platinum filled that portion of the active via hole that resides between the first and second active via ends. 
     
     
       14. The feedthrough of  claim 1  including an electrically conductive cap or protrusion co-fired to the platinum fill on the body fluid side. 
     
     
       15. The feedthrough of claim  14  1, wherein the cap or protrusion bond pad comprises platinum or titanium. 
     
     
       16. The feedthrough of  claim 1 , including an adhesion metallization disposed on an outside outer circumferential surface of the alumina substrate and a wetting metallization disposed on the adhesion metallization. 
     
     
       17. The feedthrough of  claim 16  including a wetting metallization disposed on the adhesion metallization. 
     
     
       18. The feedthrough of claim  17  including a ferrule disposed around the alumina substrate 16, wherein a gold braze hermetically seals the ferrule to the adhesion and wetting metallizations disposed on the alumina substrate. 
     
     
       19. The feedthrough of  claim 18  including a gold braze hermetically sealing the alumina substrate to the ferrule. 
     
     
       20. The feedthrough of claim  19  18, wherein the braze between the alumina substrate and the ferrule has a leak rate at least no greater than 1×10 −7  cc He/sec. 
     
     
       21. The feedthrough of claim  20  1, wherein the ferrule comprises titanium. 
     
     
       22. The feedthrough of  claim 16 , wherein the adhesion metallization comprises titanium and the wetting metallization comprises niobium or molybdenum. 
     
     
       23. The feedthrough of  claim 17  wherein the wetting metallization comprises niobium or molybdenum. 
     
     
       24. The feedthrough of  claim 1 , wherein the alumina dielectric substrate comprises a castellation recess disposed on the substrate device side, and wherein a monolithic chip capacitor is disposed within the castellation recess, the monolithic chip capacitor comprising an active electrode plate set disposed parallel to a ground electrode plate set, the active electrode plate set being electrically connected to the substantially closed-pore platinum disposed in the active via hole by a first circuit trace disposed within the alumina substrate, and the ground electrode plate set being electrically connected to an outer metallization disposed on the alumina substrate by a second circuit trace disposed within the alumina substrate. 
     
     
       25. The feedthrough of  claim 24  including a monolithic chip capacitor disposed within the castellation recess, the monolithic chip capacitor comprising an active electrode plate set disposed parallel to a ground electrode plate set. 
     
     
       26. The feedthrough of  claim 25  wherein the active electrode plate set is electrically coupled to the platinum fill by a first circuit trace disposed within the alumina substrate, and wherein the ground electrode plate set is electrically coupled to the adhesion metallization by a second circuit trace disposed within the alumina substrate. 
     
     
       27. The feedthrough of  claim 1 , including a feedthrough capacitor attached to the alumina dielectric substrate. 
     
     
       28. The feedthrough of  claim 27 , including wherein an insulative washer is disposed between the alumina substrate and the feedthrough capacitor. 
     
     
       29. The feedthrough of  claim 27 , wherein the feedthrough capacitor comprises a second dielectric substrate, a conductive capacitor via hole disposed through the second dielectric substrate, a set of active electrode plates disposed within the second dielectric substrate and being electrically coupled to the conductive capacitor via hole, an outside outer feedthrough capacitor metallization disposed on an outside outer surface of the feedthrough capacitor, and a set of ground electrode plates disposed within the second dielectric substrate and being electrically coupled to the outside feedthrough capacitor metallization. 
     
     
       30. The feedthrough of  claim 29 , wherein the set of ground electrode plates and the outside outer feedthrough capacitor metallization are electrically coupled to a ferrule. 
     
     
       31. The feedthrough of  claim 29 , including a ball grid solder joint or braze electrically coupling the set of active electrode plates to the conductive capacitor via hole and to the substantially closed-pore platinum fill in the active via hole extending through the alumina substrate of the feedthrough. 
     
     
       32. The feedthrough of  claim 31 , including a substrate device side wire disposed within the conductive feedthrough capacitor via hole and being electrically coupled to the substantially closed-pore platinum fill in the active via hole extending through the alumina substrate of the feedthrough and also being electrically coupled to the set of active electrode plates of the feedthrough capacitor by the ball grid solder joint or braze. 
     
     
       33. The feedthrough of  claim 1 , including at least one grounded ground via hole disposed through the alumina substrate from, the ground via hole extending to the substrate body fluid side and to the substrate device side, wherein a substantially pure grounded ground platinum fill is disposed within the at least one grounded ground via hole, thereby forming a platinum filled grounded ground via hole that is an electrically conductive between path to the substrate body fluid side and to the substrate device side. 
     
     
       34. The feedthrough of  claim 33 , including a set of feedthrough ground plates disposed within the alumina substrate, the feedthrough ground plate being electrically coupled to the ground platinum filled grounded in the ground via hole and to the ferrule and, wherein the ground platinum in the ground via hole is in a non-conductive relation to with the substantially closed-pore platinum filled in the active via hole. 
     
     
       35. The feedthrough of  claim 34 , including an internally grounded feedthrough capacitor disposed adjacent to the alumina dielectric substrate. 
     
     
       36. The feedthrough of  claim 35 , wherein the internally grounded feedthrough capacitor comprises a second dielectric substrate, at least one conductive capacitor via hole disposed extending through the second dielectric substrate, a set of active electrode plates disposed within the second dielectric substrate and being electrically coupled to the at least one conductive capacitor via hole, a conductive grounded ground via hole disposed extending through the second dielectric substrate, and a set of ground electrode plates disposed within the second dielectric substrate and being electrically coupled to the conductive grounded  ground platinum disposed within the at least one ground via hole in the second dielectric substrate, and wherein the internally grounded feedthrough capacitor does not have an external metallization on an outer surface of the second dielectric substrate and the set of ground electrode plates do not extend to the outer surface of the second dielectric substrate. 
     
     
       37. The feedthrough of  claim 36 , including a leadwire comprising a leadwire first end spaced from a leadwire second end, wherein the leadwire first end is connectable at a first end to an AIMD electronic circuit, and at its wherein the leadwire second end is disposed within and electrically coupled to the at least one conductive capacitor via and hole extending through the second dielectric substrate of the feedthrough capacitor where the leadwire second end is conductively connected to the set of active electrode plates disposed within the second dielectric substrate. 
     
     
       38. The feedthrough of  claim 37 , including a ground leadwire connectable at a  comprising a ground leadwire first end spaced from a ground leadwire second end, wherein the ground leadwire first end is connectable to an AIMD electronic circuit, and at its wherein the ground leadwire second end is disposed within and electrically coupled to the feedthrough capacitor conductive grounded ground via and hole extending through the second dielectric substrate of the feedthrough capacitor where the ground leadwire second end is conductively connected to the set of ground electrode plates disposed within the second dielectric substrate. 
     
     
       39. The feedthrough of  claim 17  including a hermetically sealed braze between the wetting metallization and an active implantable medical device housing. 
     
     
       40. The feedthrough of  claim 33 , wherein the at least one grounded ground via hole extending through the alumina substrate and the ground platinum fill disposed within the at least one ground via hole comprise at least two cross sectional areas. 
     
     
       41. The feedthrough of  claim 1  including, wherein the bond pad comprises a conductive leadwire disposed within the substantially closed-pore platinum fill on in the active via hole adjacent to at least the substrate body fluid side. 
     
     
       42. The feedthrough of  claim 41 , wherein the conductive leadwire comprises platinum. 
     
     
       43. The feedthrough of  claim 41 , wherein the conductive leadwire and the substantially closed-pore platinum fill are characterized as having been co-fired. 
     
     
       44. The feedthrough of  claim 1  including a crimp post disposed within the platinum fill on the body fluid side. 
     
     
       45. The feedthrough of  claim 1  including a double-sided crimp post disposed through the platinum fill, wherein the double-sided crimp post comprises a first crimp post end on the body fluid side and a second crimp post end on the device side. 
     
     
       46. The feedthrough of  claim 1 , wherein a resistance of the substantially closed-pore platinum fill from disposed within the active via hole and extending to the substrate body fluid side and to the substrate device side is less than about 0.5 ohms. 
     
     
       47. The feedthrough of  claim 1 , wherein a resistance of the substantially closed-pore platinum fill from disposed within the active via hole and extending to the substrate body fluid side and to the substrate device side is less than about 0.3 ohms. 
     
     
       48. The feedthrough of  claim 1 , wherein a resistance of the substantially closed-pore platinum fill from disposed within the active via hole and extending to the substrate body fluid side and to the substrate device side is less than about 10 milliohms. 
     
     
       49. A hermetically sealed feedthrough that is attachable to an active implantable medical device (AIMD), the feedthrough comprising:
 a) an electrically conductive ferrule comprising a ferrule sidewall defining a ferrule opening extending to a ferrule body fluid end surface and to a ferrule device side end surface, wherein, when the ferrule is attached to an opening in a housing of an AIMD, the ferrule body fluid end surface and the ferrule device side end surface reside outside the AIMD and inside the AIMD, respectively; 
 b) an alumina substrate comprised of at least 96% alumina and having a thickness extending from to a substrate body fluid side and to a substrate device side, wherein the alumina substrate resides in the ferrule opening where the alumina substrate is hermetically sealed to the ferrule; 
 b)c) a via hole disposed through the alumina substrate from, the via hole extending to the substrate body fluid side and to the substrate device side, wherein a counter-bore in the substrate is aligned with the via hole and has a depth that extends from the substrate body fluid side part-way into the substrate thickness; 
 c)d) a substantially closed pore and substantially pureclosed-pore platinum fill disposed withinin the via hole and extending betweento the counter-bore at the substrate body fluid side and to or adjacent to the substrate device side of the alumina substrate; and 
 d) a hermetic seal between the platinum fill ande) wherein the platinum in the via hole is hermetically sealed to the alumina substrate, and  
 e)f) wherein the hermetic seal has a leak rate that is no greater than 1×10 −7  std cc He/sec,; and  
 f)g) an electrically conductive bond pad comprising a pad portion and a post, wherein the pad portion resides in the counter-bore with the post extending into the platinum in the via hole, and 
 h) wherein the platinum fill forms a tortuous and mutually conformal knitline or interface between the alumina substrate and the platinum fill pad portion of the bond pad has an uninterrupted upper surface of a width that is greater than a diameter of the via hole, and 
 i) wherein the combined length of the pad portion and the post of the bond pad is less than the substrate thickness. 
 
     
     
       50. The feedthrough of  claim 49  wherein the knitline comprises a glass that is at least about 60% silica. 
     
     
       51. The feedthrough of  claim 49 , wherein an inherent shrink rate during a heat treatment of the alumina substrate in a substrate green state is equal to or up to 20% greater than an inherent co-fired shrink rate of the substantially closed-pore platinum fill in a platinum green state. 
     
     
       52. A hermetically sealed feedthrough that is attachable to an active implantable medical device (AIMD), the feedthrough comprising:
 a) an electrically conductive ferrule comprising a ferrule sidewall defining a ferrule opening extending to a ferrule body fluid end surface and to a ferrule device side end surface, wherein, when the ferrule is attached to an opening in a housing of an AIMD, the ferrule body fluid end surface and the ferrule device side end surface reside outside the AIMD and inside the AIMD, respectively; 
 b) an alumina substrate comprised of at least 96% alumina and having a thickness extending from to a substrate body fluid side and to a substrate device side, wherein the alumina substrate resides in the ferrule opening where the alumina substrate is hermetically sealed to the ferrule; 
 b) ac) an active via hole disposed through the alumina substrate from, the active via hole extending to the substrate body fluid side and to the substrate device side; 
 c)d) a first substantially closed pore and substantially pureclosed-pore platinum fill disposed within in the active via hole and, the substantially closed-pore platinum extending between to the substrate body fluid side and to or adjacent to the substrate device side of the alumina substrate, wherein the first substantially closed-pore platinum fill forms a tortuous and mutually conformal knitline or interface between in the active via hole forms a first hermetic seal with the alumina substrate and the platinum fill; at a first tortuous and mutually conformal knitline, and 
 d) a hermetic seal between the first platinum fill and the alumina substrate,e) wherein the first hermetic seal has a leak rate that is no greater than 1×10 −7  std cc He/sec; 
 e)f) a groundedground via hole disposedextending through the alumina substrate fromto the substrate body fluid side and to the substrate device side; 
 f)g) a second substantially closed poreclosed-pore platinum fill disposed within in the grounded ground via hole and extending between to the substrate body fluid side and to or adjacent to the substrate device side of the alumina substrate;, wherein the second substantially closed-pore platinum in the ground via hole forms a second hermetic seal with the alumina substrate at a second tortuous and mutually conformal knitline, and 
 g) a second hermetic seal between the second platinum fill and the alumina substrate,h) wherein the second hermetic seal has a leak rate that is no greater than 1×10 −7  std cc He/sec; 
 h)i) at least one groundedground electrode plate that is electrically coupled to the second groundedsubstantially closed-pore platinum filleddisposed within the ground via andhole, but is in a non-conductive relation towith the first substantially closed-pore platinum filleddisposed within the active via hole; and 
 i)j) an outer metallization disposed on the alumina dielectric substrate and being electrically connected to the plurality of grounded at least one ground electrode plates plate, 
 k) wherein at least one of the active via hole and the ground via hole has a counter-bore aligned with the via hole, the counter-bore having a depth that extends from the substrate body fluid side part-way into the substrate thickness; and 
 l) an electrically conductive bond pad comprising a pad portion and a post, wherein the pad portion resides in the counter-bore with the post extending into the first and second substantially closed-pore platinum in the respective at least one of the active via hole and the ground via hole, and 
 m) wherein the pad portion of the bond pad has an uninterrupted upper surface of a width that is greater than a diameter of the via hold, and 
 n) wherein the combined length of the pad portion and the post of the bond pad is less than the substrate thickness. 
 
     
     
       53. The feedthrough of  claim 52 , wherein the knitline first and second knitlines formed by the respective first and second substantially closed-pore platinum fill and the alumina dielectric substrate comprises each comprise a glass that is at least about 60% silica. 
     
     
       54. The feedthrough of  claim 52 , wherein an inherent shrink rate during a heat treatment of the alumina substrate in a substrate green state is greater than a shrink rate of the first and second substantially closed-pore platinum fills in a their respective platinum green state states. 
     
     
       55. A hermetically sealed feedthrough that is attachable to an active implantable medical device, the feedthrough comprising:
 a) an electrically conductive ferrule comprising a ferrule sidewall defining a ferrule opening extending to a ferrule body fluid end surface and to a ferrule device side end surface, wherein, when the ferrule is attached to an opening in a housing of an AIMD, the ferrule body fluid end surface and the ferrule device side end surface reside outside the AIMD and inside the AIMD, respectively;   b) an alumina substrate comprised of at least 96% alumina and having a thickness extending to a substrate first side and to a substrate second side, wherein the alumina substrate resides in the ferrule opening where the alumina substrate is hermetically sealed to the ferrule;   c) an active via hole extending through the alumina substrate to the substrate first side and to the substrate second side, wherein a counter-bore in the substrate is aligned with the active via hole and has a depth that extends from the substrate first side part-way into the substrate thickness;   d) a substantially closed-pore platinum that is hermetically sealed to the alumina substrate in the active via hole, the substantially closed-pore platinum extending to the counter-bore at the substrate first side and to or adjacent to the substrate second side; and   e) an electrically conductive bond pad comprising a pad portion and a post, wherein the pad portion resides in the counter-bore with the post extending into the substantially closed-pore platinum in the active via hole, and   f) wherein the pad portion of the bond pad has an uninterrupted upper surface of a width that is greater than a diameter of the via hole, and   g) wherein the combined length of the pad portion and the post of the bond pad is less than the substrate thickness.   
     
     
       56. The feedthrough of claim 55, wherein the pad portion of the bond pad has a height that is greater than the depth of the counter-bore so that part of the pad portion extends outwardly beyond the substrate body fluid side bordering the counter-bore. 
     
     
       57. The feedthrough of claim 55, wherein the hermetic seal has a leak rate at least no greater than 1×10 −7  std cc He/sec. 
     
     
       58. The feedthrough of claim 55, wherein the substantially closed-pore platinum resides in the counter-bore contacting the pad portion of the bond pad. 
     
     
       59. A hermetically sealed feedthrough that is attachable to an active implantable medical device, the feedthrough comprising:
 a) an electrically conductive ferrule comprising a ferrule sidewall defining a ferrule opening extending to a ferrule body fluid end surface and to a ferrule device side end surface, wherein, when the ferrule is attached to an opening in a housing of an AIMD, the ferrule body fluid end surface and the ferrule device side end surface reside outside the AIMD and inside the AIMD, respectively;   b) an alumina substrate comprised of at least 96% alumina and having a thickness extending to a substrate first side and to a substrate second side, wherein the alumina substrate resides in the ferrule opening where the alumina substrate is hermetically sealed to the ferrule;   c) an active via hole extending through the alumina substrate to the substrate first side and to the substrate second side, wherein a counter-bore in the substrate is aligned with the active via hole and has a depth that extends from the substrate first side part-way into the substrate thickness;   d) a substantially closed-pore platinum that is hermetically sealed to the alumina substrate in the active via hole, the substantially closed-pore platinum extending to the counter-bore at the substrate first side and to or adjacent to the substrate second side; and   e) an electrically conductive leadwire connection feature extending to a leadwire connection feature first portion having a leadwire connection feature first end and to a leadwire connection feature second portion, wherein the leadwire connection feature first portion is seated on the substrate first side in the counter-bore with the leadwire connection feature first end residing adjacent to the substrate first side, and wherein the leadwire connection feature second portion extends into the substantially closed-pore platinum in the active via hole, and   f) wherein the leadwire connection feature first portion has an uninterrupted upper surface of a width that is greater than a diameter of the via hole, and   g) wherein the combined length of the leadwire connection feature first and second portions is less than the substrate thickness.   
     
     
       60. The feedthrough of claim 59, wherein the leadwire connection feature first end is substantially flush with the substrate first side bordering the counter-bore. 
     
     
       61. The feedthrough of claim 59, wherein the leadwire connection feature first end is proud of the substrate first side bordering the counter-bore. 
     
     
       62. The feedthrough of claim 59, wherein the leadwire connection feature first portion has a larger cross-section perpendicular to a longitudinal axis of the leadwire connection feature than the leadwire connection feature second portion. 
     
     
       63. The feedthrough of claim 59, wherein the leadwire connection feature is selected from the group consisting of a wire, a bond pad having a rounded nail head, and a bond pad having a flat nail head. 
     
     
       64. A feedthrough insulator substrate assembly, comprising:
 a) an insulator substrate having a thickness extending to a substrate body fluid side and to a substrate device side, wherein the insulator substrate resides in the ferrule opening where the substrate is hermetically sealed to the ferrule;   b) an active via hole extending through the insulator substrate to the substrate body fluid side and to the substrate device side, wherein a counter-bore in the substrate is aligned with the active via hole and has a depth that extends from the substrate body fluid side part-way into the substrate thickness;   c) a substantially closed-pore platinum that is hermetically sealed to the insulator substrate in the active via hole, the substantially closed-pore platinum extending to the counter-bore at the substrate body fluid side and to or adjacent to the substrate device side; and   d) an electrically conductive bond pad comprising a pad portion and a post, wherein the pad portion resides in the counter-bore, seated on the substrate body fluid side with the post extending into the substantially closed-pore platinum in the active via hole, and wherein the pad portion of the bond pad has a height that is greater than the depth of the counter-bore so that part of the pad portion in the counter-bore extends outwardly beyond the substrate body fluid side bordering the counter-bore, and wherein the substantially closed-pore platinum resides in the counter-bore contacting the pad portion of the bond pad, and   e) wherein the pad portion of the bond pad has an uninterrupted upper surface of a width that is greater than a diameter of the via hole, and   f) wherein the combined length of the pad portion and the post of the bond pad is less than the substrate thickness.   
     
     
       65. The feedthrough of claim 64, wherein the bond pad is selected from the group consisting of a wire providing the pad portion and the post, a nail having a rounded nail head, and a nail having a flat nail head. 
     
     
       66. The feedthrough of claim 1, wherein the bond pad is selected from the group consisting of a wire providing the pad portion and the post, a nail having a rounded nail head, and a nail having a flat nail head. 
     
     
       67. The feedthrough of claim 49, wherein the bond pad is selected from the group consisting of a wire providing the pad portion and the post, a nail having a rounded nail head, and a nail having a flat nail head. 
     
     
       68. The feedthrough of claim 52, wherein the bond pad is selected from the group consisting of a wire providing the pad portion and the post, a nail having a rounded nail head, and a nail having a flat nail head. 
     
     
       69. The feedthrough of claim 55, wherein the bond pad is selected from the group consisting of a wire providing the pad portion and the post, a nail having a rounded nail head, and a nail having a flat nail head. 
     
     
       70. The feedthrough of claim 1, wherein the pad portion of the bond pad has a height that is greater than the depth of the counter-bore so that part of the pad portion extends outwardly beyond the substrate body fluid side bordering the counter-bore. 
     
     
       71. The feedthrough of claim 1, wherein the substantially closed-pore platinum resides in the counter-bore contacting the pad portion of the bond pad. 
     
     
       72. The feedthrough of claim 1, wherein the pad portion of the bond pad resides in the counter-bore, seated on the substrate body fluid side with the post extending into the substantially closed-pore platinum in the active via hole. 
     
     
       73. The feedthrough of claim 1, wherein the uninterrupted upper surface of the pad portion of the bond pad is either flush or proud of the substrate body fluid side surrounding the counterbore. 
     
     
       74. A hermetically sealed feedthrough that is attachable to an active implantable medical device (AIMD), the feedthrough comprising:
 a) an electrically conductive ferrule comprising a ferrule sidewall defining a ferrule opening extending to a ferrule body fluid end surface and to a ferrule device side end surface, wherein, when the ferrule is attached to an opening in a housing of an AIMD, the ferrule body fluid end surface and the ferrule device side end surface reside outside the AIMD and inside the AIMD, respectively;   b) an alumina substrate comprised of at least 96% alumina and having a thickness extending to a substrate body fluid side and to a substrate device side, wherein the alumina substrate resides in the ferrule opening where the alumina substrate is hermetically sealed to the ferrule;   c) an active via hole extending through the alumina substrate to the substrate body fluid side and to the substrate device side;   d) a substantially closed-pore platinum that is hermetically sealed to the alumina substrate in the active via hole, the substantially closed-pore platinum extending to or adjacent to the substrate body fluid side and to or adjacent to the substrate device side; and   e) an electrically conductive double-sided crimp post disposed through the substantially closed-pore platinum in the active via hole, the double-sided crimp post comprising a crimp post first end adjacent to the substrate body fluid side and a crimp post second end adjacent to the substrate device side.