Filtered feedthrough assemblies for implantable devices and methods of manufacture
A solder joint between a capacitive element and a ferrule of a filtered feedthrough assembly for an implantable medical device is formed from a solder pre-form mounted on a portion of an external surface of the capacitive element, which portion of the external surface may be overlaid with a layer including a noble metal. Another solder joint may be formed between the capacitive member and each feedthrough pin; and, for an assembly including a plurality of feedthrough pins, each of the other solder joints may be formed from a solder pre-form mounted onto the external surface of the capacitive element by inserting each pin through a corresponding ring of a plurality of rings connected together to form the solder pre-form.
1. A filtered feedthrough assembly for an implantable medical device, the assembly comprising:
a ferrule;
a feedthrough pin extending within the ferrule;
a capacitive element located within the ferrule, the capacitive element including a bore, through which the pin extends, and an external surface extending laterally outward from an opening of the bore; and
a first solder joint coupling the capacitive element to the ferrule;
wherein the external surface of the capacitive element includes a first portion adjacent to the first solder joint, the first portion being overlaid with a layer comprising a noble metal.
2. The assembly of claim 1 , further comprising a non-conductive strain-relief member mounted on the external surface of the capacitive element and surrounding the pin.
3. The assembly of claim 1 , further comprising:
a second solder joint coupling the capacitive element to the pin; and
wherein the external surface of the capacitive element further includes a second portion adjacent the second solder joint, the second portion being overlaid with a layer comprising a noble metal.
4. The assembly of claim 3 , further comprising a non-conductive strain-relief member mounted over the second solder joint and surrounding the pin.
5. A solder pre-form used in manufacturing a feedthrough assembly for an implantable medical device, the solder pre-form comprising a plurality of rings connected together, each ring of the plurality of rings having an inner diameter sized to fit around a feedthrough pin of the feedthrough assembly.
6. The solder pre-form of claim 5 , wherein the plurality of rings are connected together by a stringer extending between adjacent rings of the plurality of rings.
7. The solder pre-form of claim 6 , wherein each stringer includes a discontinuity.
8. The solder pre-form of claim 5 , further comprising an outer member extending alongside the plurality of rings and being connected to at least one ring of the plurality of rings.
9. The solder pre-form of claim 5 , further comprising an outer member extending alongside the plurality of rings; and wherein the plurality of rings are connected together by the outer member, and at least one stringer extends between each ring of the plurality of rings and the outer member.
10. The solder pre-form of claim 9 , wherein each of the at least one stringers includes a discontinuity.
11. The solder pre-form of claim 5 , further comprising an outer member extending alongside the plurality of rings and being connected to at least one ring of the plurality of rings; wherein the outer member includes a bend for conforming around an edge of a capacitive element of the feedthrough assembly.
12. An implantable medical device comprising a housing and a filtered feedthrough assembly extending therethrough, the filtered feedthrough assembly comprising:
a ferrule coupled to the housing of the device;
a feedthrough pin extending within the ferrule;
a capacitive element located within the ferrule, the capacitive element including a bore, through which the pin extends, and an external surface extending laterally outward from an opening of the bore; and
a first solder joint coupling the capacitive element to the ferrule;
wherein the external surface of the capacitive element includes a first portion adjacent to the first solder joint, the first portion being overlaid with a layer comprising a noble metal.
13. The device of claim 12 , wherein the feedthrough assembly further comprises a non-conductive strain-relief member mounted on the external surface of the capacitive element and surrounding the pin.
14. The device of claim 12 , wherein the feedthrough assembly further comprises:
a second solder joint coupling the capacitive element to the pin; and
wherein the external surface of the capacitive element further includes a second portion adjacent the second solder joint, the second portion being overlaid with a layer comprising a noble metal.
15. The device of claim 14 , wherein the feedthrough assembly further comprises a non-conductive strain-relief member mounted over the second solder joint and surrounding the pin.
16. The solder pre-form of claim 5 wherein the solder pre-form comprises tin, gold, or indium.