Gold wetting on ceramic surfaces upon coating with titanium hydride

Patent metadata

Field	Value
Publication number	US-2018085591-A1
Application number	US-201715712669-A
Country	US
Kind code	A1
Filing date	Sep 22, 2017
Priority date	Sep 23, 2016
Publication date	Mar 29, 2018
Grant date	—

Abstract

The application of a titanium hydride coating on a ceramic, preferably an alumina ceramic, as a facile and inexpensive approach to bond gold to the ceramic during brazing is described. During the brazing process, the deposited titanium hydride is first partially decomposed to form pure titanium intermixed with titanium hydride. The combination of pure titanium and titanium hydride contributes to improved adhesion of gold with the alumina ceramic without any detrimental reaction between pure titanium and gold. The titanium hydride coating can be applied by dip/spray/paint coating.

First claim

What is claimed is:

1 . A hermetic feedthrough for an implantable medical device, the feedthrough comprising:
a) a ferrule defining a ferrule opening, wherein the ferrule is configured to be attachable to an opening in a housing of an implantable medical device; b) an insulator at least partially residing in the ferrule opening where a first gold braze hermetically seals the insulator to the ferrule, wherein at least one insulator passageway extends through the insulator to an insulator first end surface and an insulator second end surface; and c) an electrically conductive terminal pin residing in the at least one insulator passageway where a second gold braze hermetically seals the terminal pin to the insulator.

2 . The feedthrough of claim 1 , wherein at least one of the first and second brazes has the following braze profile: insulator/titanium and titanium hydride mixture/gold/ferrule or terminal pin, as the case may be.

3 . The feedthrough of claim 2 , wherein, in the braze profile for at least one of the first and second brazes, the titanium and titanium hydride mixture includes residual inorganic binders.

4 . The feedthrough of claim 1 , wherein both of the first and second brazes have the following braze profile: insulator/titanium and titanium hydride mixture/gold/ferrule or terminal pin, as the case may be.

5 . The feedthrough of claim 4 , wherein, in the first and second braze profiles, the titanium and titanium hydride mixture includes residual inorganic binders.

6 . The feedthrough of claim 1 , wherein the ferrule is selected from the group consisting of titanium, tantalum, niobium, stainless steel, and combinations of alloys thereof.

7 . The feedthrough of claim 1 , wherein the insulator is selected from the group consisting of an alumina ceramic, aluminum nitride, boron nitride, silicon carbide, glass, or combinations thereof

8 . The feedthrough of claim 1 , wherein the terminal pin is selected from the group consisting of platinum, platinum-iridium alloys, palladium, and palladium alloys.

9 . The feedthrough of claim 1 , wherein the terminal pin extends from a terminal pin first portion to a terminal pin second portion, and wherein the terminal pin first portion extends outwardly beyond the insulator first end surface and the terminal pin second portion extends outwardly beyond the insulator second end surface.

10 . A method for providing a hermetic feedthrough, comprising the steps of:
a) providing an insulator, the insulator comprising an insulator outer side wall extending to an insulator first end surface and an insulator second end surface, wherein at least one insulator passageway is defined by an insulator inner surface extending through the insulator to the insulator first and second end surfaces; b) contacting at least a portion of the insulator outer sidewall and at least a portion of the insulator inner surface with a coating comprising titanium hydride; c) providing a ferrule defining a ferrule opening, wherein the ferrule is configured to be attachable to an opening in a housing of an implantable medical device; d) providing an electrically conductive terminal pin; e) positioning the insulator in the ferrule opening and positioning the terminal pin in the at least one insulator passageway; f) positioning a first gold fillet surrounding the insulator outer surface adjacent to the ferrule opening and positioning a second gold fillet surrounding the terminal pin adjacent to the at least one insulator passageway to thereby construct a feedthrough sub-assembly; and g) heating the feedthrough sub-assembly to first partially decompose the titanium hydride to form a mixture of titanium and titanium hydride and then further heating the feedthrough sub-assembly to melt the first and second gold fillets to thereby form a first hermetic braze sealing the insulator to the ferrule and a second hermetic braze sealing the terminal pin to the insulator.

11 . The method of claim 10 , wherein both of the first and second brazes have the following braze profile: insulator/titanium and titanium hydride mixture/gold/ferrule or terminal pin, as the case may be.

12 . The method of claim 10 , including mixing a binder with the titanium hydride prior to contacting at least a portion of the insulator cuter sidewall and at least a portion of the insulator inner surface with the titanium hydride coating, wherein, in the first and second braze profiles, the mixture of titanium and titanium hydride includes residual inorganic binders.

13 . The method of claim 12 , including selecting the binder from the group consisting of polyethylene glycol, methyl cellulose, colloidal silica, sodium silicate aqueous dispersions, and mixtures thereof.

14 . The method of claim 10 , including heating the feedthrough sub-assembly in a vacuum having a pressure that ranges from 10 −1 Torr to 10 −9 Torr.

15 . The method of claim 10 , including heating the feedthrough sub-assembly at a temperature that ranges from about 400° C. to about 1,000° C. for about 30 to about 180 minutes.

16 . A method for providing a hermetic feedthrough, comprising the steps of:
a) providing an insulator, the insulator comprising an insulator outer sidewall extending to an insulator first end surface and an insulator second end surface, wherein at least one insulator passageway is defined by an insulator inner surface extending through the insulator to the insulator first and second end surfaces; b) contacting at least a portion of the insulator outer sidewall and at least a portion of the insulator inner surface with a coating comprising titanium hydride; c) heating the feedthrough sub-assembly to partially decompose the titanium hydride to form a mixture of titanium and titanium hydride contacting the insulator outer sidewall and the insulator inner surface; d) providing a ferrule defining a ferrule opening, wherein the ferrule is configured to be attachable to an opening in a housing of an implantable medical device; e) providing an electrically conductive terminal pin; f) positioning the insulator in the ferrule opening and positioning the terminal pin in the at least one insulator passageway; g) positioning a first gold fillet surrounding the insulator outer surface adjacent to the ferrule opening and positioning a second gold fillet surrounding the terminal pin adjacent to the at least one insulator passageway to thereby construct a feedthrough sub-assembly; and h) further heating the feedthrough sub-assembly to melt the first and second gold fillets to thereby form a first hermetic braze sealing the insulator to the ferrule and a second hermetic braze sealing the terminal pin to the insulator.

17 . The method of claim 16 , wherein both of the first and second brazes have the following braze profile: insulator/titanium and titanium hydride mixture/gold/ferrule or terminal pin, as the case may be.

18 . The method of claim 16 , including mixing a binder with the titanium hydride prior to contacting at least a portion of the insulator outer sidewall and at least a portion of the insulator inner surface with the titanium hydride coating, wherein, in the first and second braze profiles, the mixture of titanium and titanium hydride includes residual inorganic binders.

19 . The method of claim 18 , including selecting the binder from the group consisting of polyethylene glycol, methyl cellulose, colloidal silica, sodium silicate aqueous dispersions, and mixtures thereof.

20 . The method of claim 16 , including h

Assignees

• Greatbatch Ltd

Inventors

• Li Dongfa
• Das Biswa P
• Shah Ashish

Classifications

• H01G2/02

  Mountings · CPC title

• H01G4/242

  the capacitive element surrounding the terminal · CPC title

• H01G4/224

  Housing; Encapsulation · CPC title

• H01G4/35

  Feed-through capacitors or anti-noise capacitors · CPC title

• A61N1/3754 Primary

  Feedthroughs · CPC title