Hermetic feed-through with hybrid seal structure
A power terminal feed-through includes a housing body, a plurality of conductive pins, and a seal structure that hermetically seals the conductive pins to the housing body and electrically insulates the conductive pins from the housing body. The seal structure includes a first material fused to one of the housing body and the conductive pin, and a second material fused to the other one of the housing body and the conductive pin. The first and second materials may be properly chosen to match thermal expansion of the housing body and the conductive pins, respectively.
1. A hermetic feed-through comprising:
a housing body;
a conductive pin; and
a seal structure that hermetically seals the conductive pin to the housing body and that provides electric insulation between the housing body and the conductive pin;
wherein the seal structure comprises a first material fused to one of the housing body and the conductive pin, and a second material fused to the first material and to the other one of the housing body and the conductive pin such that the seal structure comprises a first sealing path, a second sealing path, and a third sealing path that are connected to form a continuous sealing boundary.
2. The hermetic feed-through of claim 1 , wherein the housing body is made of a first metal, the first metal having a coefficient of thermal expansion matching that of the first material, the conductive pin being made of a second metal, the second metal having a coefficient of thermal expansion matching that of the second material.
3. The hermetic feed-through of claim 2 , wherein the first material has a gas permeation prevention property better than that of the second material.
4. The hermetic feed-through of claim 3 , wherein the second material has a fusing temperature lower than that of the first material.
5. The hermetic feed-through of claim 1 , further wherein the first sealing path is a glass-to-metal seal, the second sealing path is a polymer-to-metal seal, and the third sealing path is a glass-to-polymer seal; and
wherein the housing body is made of a first metal, the first metal having a coefficient of thermal expansion matching that of the first material, and the conductive pin is made of a second metal, the second metal having a coefficient of thermal expansion matching that of the second material.
6. The hermetic feed-through of claim 1 , wherein the first material is glass, the second material is epoxy, the housing body is made of steel, and the conductive pin includes at least one of copper, silver, and gold.
7. The hermetic feed-through of claim 1 , wherein the third sealing path forms an angled portion between the first material and the second material.
8. The hermetic feed-through of claim 1 , wherein the seal structure further comprises a third material fused to the second material such that the seal structure comprises a fourth sealing path.
9. The hermetic feed-through of claim 8 wherein the first sealing path is a glass-to-metal seal, the second sealing path is a polymer-to-metal seal, the third sealing path is a glass-to-polymer seal, and the fourth sealing path is a glass-to-polymer seal.
10. The hermetic feed-through of claim 9 , wherein the first and second sealing paths are parallel to one another; and
wherein the third and fourth sealing paths are parallel to one another.
11. A hermetic feed-through comprising:
a housing comprising an aperture therethrough;
a conductive pin having a longitudinal axis and extending in a direction along the longitudinal axis through the aperture in the housing; and
a seal structure hermetically sealing the conductive pin to the housing and electrically insulating the conductive pin from the housing;
the seal structure comprising a first dielectric material, a second dielectric material and at least three sealing paths extending parallel to the direction of the longitudinal axis, a first sealing path located between the first dielectric material and the housing, a second sealing path located between the second dielectric material and the pin, and a third sealing path located between the first dielectric material and the second dielectric material; and
wherein the first sealing path comprises a glass-to-metal seal, the second sealing path comprises a polymer-to-metal seal, and the third sealing path comprises a glass-to-polymer seal.
12. The hermetic feed-through of claim 11 , wherein the second dielectric material comprises a flange portion extending perpendicularly to the longitudinal axis; and
wherein the seal structure further comprises a fourth sealing path extending perpendicularly to the direction of the longitudinal axis, the fourth sealing path located between the flange portion of the second dielectric material and first the dielectric material.
13. The hermetic feed-through of claim 11 wherein the first dielectric material comprises a sealing glass and the second dielectric material comprises a polymer; and
wherein the housing comprises a first metal having a coefficient of thermal expansion matching that of the sealing glass, and the conductive pin comprises a second metal having a coefficient of thermal expansion matching that of the polymer.
14. A hermetic feed-through comprising:
a housing comprising an aperture therethrough;
a conductive pin having a longitudinal axis and extending in a direction along the longitudinal axis through the aperture in the housing; and
a seal structure hermetically sealing the conductive pin to the housing and electrically insulating the conductive pin from the housing;
the seal structure comprising a first dielectric material, a second dielectric material, a third dielectric material and four sealing paths extending parallel to the direction of the longitudinal axis, a first sealing path located between the first dielectric material and the housing, a second sealing path located between the second dielectric material and the pin, a third sealing path located between the first dielectric material and the third dielectric material, and a fourth sealing path located between the second dielectric material and the third dielectric material.
15. The hermetic feed-through of claim 14 , wherein the housing comprises aluminum.
16. The hermetic feed-through of claim 14 wherein the first and second sealing paths comprise a polymer-to-metal seal, and the third and fourth sealing paths comprise a glass-to-polymer seal.
17. The hermetic feed-through of claim 14 wherein the first and third dielectric materials comprise a polymer, and the second dielectric material comprises a sealing glass; and
wherein the housing comprises a first metal having a coefficient of thermal expansion matching that of the first dielectric material, and the conductive pin comprises a second metal having a coefficient of thermal expansion matching that of the third dielectric material.