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Terminal pins that include a refractory metal partially welded to a terminal block of a dissimilar metal incorporated into feedthrough filter capacitor assemblies are discussed. The feedthrough filter capacitor assemblies are particularly useful for incorporation into implantable medical devices suc

Terminal pins that include a refractory metal partially welded to a terminal block of a dissimilar metal incorporated into feedthrough filter capacitor assemblies are discussed. The feedthrough filter capacitor assemblies are particularly useful for incorporation into implantable medical devices such as cardiac pacemakers, cardioverter defibrillators, and the like, to decouple and shield internal electronic components of the medical device from undesirable electromagnetic interference (EMI) signals.

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1. A feedthrough assembly, which comprises: a) an insulator of electrically non-conductive material comprising an insulator sidewall, having an outer insulator surface extending from a first insulator end to a second insulator end, wherein the insulator has at least one terminal pin bore extending t

1. A feedthrough assembly, which comprises: a) an insulator of electrically non-conductive material comprising an insulator sidewall, having an outer insulator surface extending from a first insulator end to a second insulator end, wherein the insulator has at least one terminal pin bore extending there through to the first and second insulator ends;b) a terminal pin comprising a first metal received in the terminal pin bore, the terminal pin having a terminal pin sidewall extending from a first terminal pin portion having a first terminal pin end to a second terminal pin end, wherein the opposed first and second terminal pin ends are spaced from the respective first and second insulator ends, and wherein the first terminal pin portion has a terminal pin perimeter;c) a ferrule of an electrically conductive material comprising a ferrule opening defined by a surrounding ferrule sidewall having an inner ferrule surface, wherein the insulator is supported in the ferrule opening;d) a terminal block of a second metal and comprising a terminal block sidewall, extending to opposed first and second terminal block ends, the terminal block having at least one terminal block bore extending there through to the first and second terminal block ends, wherein the first terminal pin portion extends through the terminal block bore with the first terminal pin end spaced above the first end of the terminal block, and wherein the second end of the terminal block faces the insulator;e) a first braze material extending from a first metallization contacting the terminal pin bore to the first metal of the terminal pin, thereby hermetically sealing the terminal pin to the insulator;f) a second braze material extending from a second metallization contacting the outer insulator surface to the inner ferrule surface to thereby hermetically seal the insulator to the ferrule; andg) a weld connecting from about 10 percent to about 60 percent of the terminal pin perimeter at the first terminal pin portion to the first terminal block end. 2. The feedthrough assembly of claim 1 wherein the first metal of the terminal pin comprises a refractory metal. 3. The feedthrough assembly of claim 1 wherein the first metal of the terminal pin is selected from the group consisting of niobium, molybdenum, tantalum, tungsten, rhenium, titanium, vanadium, zirconium, hafnium, osmium, iridium, and alloys thereof. 4. The feedthrough assembly of claim 1 wherein the weld is a laser weld. 5. The feedthrough assembly of claim 4 wherein the laser weld is characterized as having been formed by a laser at a welding energy of from about 0.5 joule to about 2.0 joule (J). 6. The feedthrough assembly of claim 4 wherein the laser weld is characterized as having been formed by a laser at a welding pulse frequency of from about 2 hertz (Hz) to about 10 hertz (Hz). 7. The feedthrough assembly of claim 4 wherein the laser weld is characterized as having been formed by a laser at a welding pulse width of from about 0.5 milliseconds (msec) to about 2.0 milliseconds (msec). 8. The feedthrough assembly of claim 1 wherein the weld connects from about 20 percent to about 80 percent of the perimeter of the terminal pin to the terminal block. 9. The feedthrough assembly of claim 1 further comprising a protective cap comprising a protective cap sidewall extending from a first protective cap end to a second protective cap end, wherein the protective cap is positioned between the second end of the terminal block and the first end of the insulator with the terminal pin residing in a protective cap throughbore extending to the first and second protective cap ends. 10. The feedthrough assembly of claim 9 wherein the protective cap is composed of a biocompatible polymeric material. 11. The feedthrough assembly of claim 9 wherein the terminal block is positioned in a slot at the first protective cap end. 12. The feedthrough assembly of claim 1 wherein the insulator and the terminal block have at least two respective terminal pin bores and terminal block bores with at least two terminal pins residing therein, and wherein welds connect from about 10 percent to about 60 percent of the first portion of each of the terminal pins to the first end of the terminal block with a remaining unwelded portion of the respective perimeters of the first terminal pin portions facing each other. 13. The feedthrough assembly of claim 1 wherein the second metal of the terminal block is selected from the group consisting of nickel, titanium, gold, silver, platinum, palladium, stainless steel, MP35N (35Co-35Ni-20Cr-10Mo), and alloys thereof. 14. The feedthrough assembly of claim 1 wherein the first terminal pin end is either spaced above or recessed below the first terminal block end. 15. A method for providing a feedthrough assembly, comprising the steps of: a) as providing a feedthrough comprising: i) an insulator of electrically non-conductive material comprising an insulator sidewall having an outer insulator surface extending from a first insulator end to a second insulator end, wherein the insulator has at least one terminal pin bore extending there through to the first and second insulator ends;ii) a terminal pin comprising a first metal received in the terminal pin bore, the terminal pin having a terminal pin sidewall extending from a first terminal pin portion having a first terminal pin end to a second terminal pin end, wherein the opposed first and second terminal pin ends are spaced from the respective first and second insulator ends, and wherein the first terminal pin portion has a terminal pin perimeter;iii) a ferrule of an electrically conductive material comprising a ferrule opening defined by a surrounding ferrule sidewall having an inner ferrule surface, wherein the insulator is supported in the ferrule opening;iv) a terminal block of a second metal and comprising a terminal block sidewall extending to opposed first and second terminal block ends, the terminal block having at least one terminal block bore extending there through to the first and second terminal block ends, wherein the first terminal pin portion extends through the terminal block bore with the first terminal pin end spaced above the first end of the terminal block and the second end of the terminal block facing the insulator;v) a first braze material extending from a first metallization contacting the terminal pin bore to the first metal of the terminal pin, thereby hermetically sealing the terminal pin to the insulator; andvi) a second braze material extending from a second metallization contacting the outer insulator surface to the inner ferrule surface to thereby hermetically seal the insulator to the ferrule; andb) welding from about 10 percent to about 60 percent of the terminal pin perimeter at the first terminal pin portion to the first terminal block end. 16. The method of claim 15 including providing the first metal of the terminal pin comprising a refractory metal. 17. The method of claim 15 including selecting the terminal pin from the group consisting of niobium, molybdenum, tantalum, tungsten, rhenium, titanium, vanadium, zirconium, hafnium, osmium, iridium, and alloys thereof. 18. The method of claim 15 including providing the weld as a laser weld. 19. The method of claim 18 including welding the first portion of the terminal pin to the first end of the terminal block by applying a laser weld energy of from about 0.5 joule (J) to about 2.0 joule (5), a welding pulse frequency of from about 2 hertz (Hz) to about 10 hertz (Hz), and a welding pulse width of from about 0.5 milliseconds (msec) to about 2.0 milliseconds (msec) to at least one of the terminal pin and the terminal block. 20. The method of claim 15 including joining from about 20 percent to about 80 percent of the perimeter of the terminal pin to the terminal block. 21. The method of claim 15 including providing a protective cap comprising a protective cap sidewall extending from a first protective cap end to a second protective cap end, wherein the protective cap is positioned between the second end of the terminal block and the first end of the insulator with the terminal pin residing in a protective cap throughbore extending to the first and second protective cap ends. 22. The method of claim 21 including providing the protective cap composed of a biocompatible polymeric material. 23. The method of claim 21 including providing the terminal block in a slot formed at the first protective cap end. 24. The method of claim 15 including providing the insulator and the terminal block having at least two respective terminal pin bores and terminal block bores with at least two terminal pins residing therein and further welding from about 10 percent to about 60 percent of the first portion of each of the terminal pins to the first end of the terminal block with a remaining unwelded portion of the respective perimeters of the first portions of the terminal pins facing each other. 25. The method of claim 15 including selecting the second metal of the terminal block from the group consisting of nickel, titanium, gold, silver, platinum, palladium, stainless steel, MP35N (35Co-35Ni-20Cr-10Mo), and alloys thereof. 26. A feedthrough assembly, which comprises: a) an insulator of electrically non-conductive material comprising an insulator sidewall having an outer insulator surface extending from a first insulator end to a second insulator end, wherein the insulator has at least one terminal pin bore extending there through to the first and second insulator ends;b) a terminal pin comprising a first metal received in the terminal pin bore, the terminal pin having a terminal pin sidewall extending from a first terminal pin portion having a first terminal pin end to a second terminal pin end, wherein the opposed first and second terminal pin ends are spaced from the respective first and second insulator ends, and wherein the first terminal pin portion has a terminal pin perimeter;c) a ferrule of an electrically conductive material comprising a ferrule opening defined by a surrounding ferrule sidewall having an inner ferrule surface, wherein the insulator is supported in the ferrule opening;d) a terminal block of a second metal and comprising a terminal block sidewall extending to opposed first and second terminal block ends, the terminal block having at least one terminal block bore extending there through to the first and second terminal block ends, wherein the first terminal pin portion resides in the terminal block bore with the first terminal pin end recessed below the first terminal block end, and wherein the second end of the terminal block faces the insulator;e) a first braze material extending from a first metallization contacting the terminal pin bore to the first metal of the terminal pin, thereby hermetically sealing the terminal pin to the insulator;f) a second braze material, extending from a second metallization contacting the outer insulator surface to the inner ferrule surface to thereby hermetically seal the insulator to the ferrule; andg) a weld connecting from about 10 percent to about 60 percent of the terminal pin perimeter at the first terminal pin end to the first terminal block end.