EP0308557B1 - Hermetically sealed electrical feedthrough - Google Patents
Hermetically sealed electrical feedthrough Download PDFInfo
- Publication number
- EP0308557B1 EP0308557B1 EP19870308514 EP87308514A EP0308557B1 EP 0308557 B1 EP0308557 B1 EP 0308557B1 EP 19870308514 EP19870308514 EP 19870308514 EP 87308514 A EP87308514 A EP 87308514A EP 0308557 B1 EP0308557 B1 EP 0308557B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- electrical conductor
- adapter
- cylindrical cavity
- glass body
- conductor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B17/00—Insulators or insulating bodies characterised by their form
- H01B17/26—Lead-in insulators; Lead-through insulators
- H01B17/30—Sealing
- H01B17/303—Sealing of leads to lead-through insulators
- H01B17/305—Sealing of leads to lead-through insulators by embedding in glass or ceramic material
Description
- This invention relates generally to electrical feedthroughs and, more particularly to an hermetically sealed coaxial cable feedthrough.
- Hermetically sealed casings are used extensively to package a variety of hybrid microcircuits. Typically, glass-to-metal seals are employed to hermetically seal and electrically isolate one or more lead wires from a package body. Generally, the hermetic seal is produced by fusing glass between the lead wire and the package body. Such hybrid packages provide, for microelectronic circuits, enclosures that are electrically accessible but completely isolated from external hostile environments.
- Significant problems encountered during the creation of hermetically sealed packages stem from requirements for internal circuitry routing. The use of either elongated pin feedthroughs or gold ribbons to reach internal circuitry often results in impedance mismatches. Conversely, the interconnection of internal circuitry and feedthrough pins with coaxial cable assemblies entails sensitive soldering procedures that can damage individual components, particularly the fragile inner conductors of the cable assemblies.
- European Patent Application EP-A-0 229 549 discloses a feedthrough assembly having an inner conductor hermetically sealed to a flange adapter by a glass bead. The adapter is adapted for connection to an outer conductor electrically isolated from the inner conductor by insulation and for mounting in a wall panel of an enclosure. However, in order to facilitate hermetic sealing to the glass bead and the wall panel, the adapter is made of a magnetic material such as ferro-nickel. Such materials provide the assembly with undesirable magnetic properties.
- The object of this invention, therefore, is to provide an improved feedthrough for hermetically sealed packages.
- According to the present invention an hermetically sealed electrical feedthrough assembly comprises an elongated inner electrical conductor having first and second ends, a glass body hermetically sealed around one length portion of the inner conductor adjacent to the first end thereof, a metal adapter with a solderable material hermetically sealed around the glass body and adapted for mounting in a wall of a housing, a tubular outer electrical conductor enclosing and coaxial with another length portion of the inner electrical conductor, the outer electrical conductor being seperated from the inner electrical conductor by an annular volume and having one end portion electrically connected to the metal adapter and an opposite end portion disposed adjacent to the second end of the inner electrical conductor and electrical insulation filling the annular volume and electrically isolating the outer electrical conductor from the length portion of the inner electrical conductor, characterized in that the inner electrical conductor and the metal adapter are made of a substantially non-magnetic material plated with a solderable material. High performance interconnections with microcircuitry in an hermetically sealed housing is facilitated by the disclosed assembly.
- According to specific features of the invention, the adapter defines an outer cylindrical cavity extending inwardly from an outer end thereof and an inner cylindrical cavity extending inwardly from an inner end thereof and coaxially aligned with the outer cylindrical cavity, the outer cylindrical cavity retaining the glass body, and the inner cylindrical cavity retaining an end section of the outer electrical conductor. These features provide the desired assembly in a structurally efficient arrangement.
- According to another feature of the invention, the adaptor defines a circumferential flange with an annular surface for engaging the wall of the housing, the annular surface facing toward the inner end. The circumferential flange accommodates mounting of the assembly in the hermetically sealed housing.
- According to still other features of the invention, the inner and outer cylindrical cavities are separated by a central cavity defined by an annular rib having an inner surface facing the inner cylindrical cavity and an outer surface facing the outer cylindrical cavity, the inner surface engages said glass body, the diameter of the inner cylindrical cavity is less than the diameter of the outer cylindrical cavity and another length portion of the inner electrical conductor extends between the second end thereof and the central cavity.
- According to yet other features of the invention, the inner electrical conductor and the adapter are made of stainless steel and plated with an alloy comprising nickel and gold and the outer electrical conductor is made of a ductile, electrically conductive material. The disclosed conductor and adapter materials facilitates both hermetic sealing and soldering operations while the ductile outer conductor is easily manipulated during interconnection procedures.
- The invention further includes a method for producing an hermetically sealed electrical feedthrough assembly and constituted by the steps of providing a cylindrical glass body with an axial passage, providing a substantially non-magnetic metal adapter with an outer cylindrical cavity extending inwardly from an outer end thereof and conforming to the glass body, providing an elongateed substantially non-magnetic inner electrical conductor, providing an elongated, tubular outer electrical conductor having an inner surface engaged by an elongated cylindrical insulator defining a central passage coaxially aligned with the outer electrical conductor and conforming in shape to the inner electrical conductor, inserting one length portion of the inner electrical conductor into the axial passage, inserting the glass body into the outer cylindrical cavity, applying heat so as to produce a hermetic seal between the glass body and both the adapter and the length portion of the inner electrical conductor, plating exposed portions of the adapter and inner electrical conductor with solderable material subsequently pressing another length portion of the inner electrical conductor into the central passage and electrically connecting the outer electrical conductor to the adapter. This method provides the desired assembly in a simple, efficient manner.
- According to the other method features of the invention, the adapter defines an inner cylindrical cavity axially aligned with the outer cylindrical cavity and a central cavity separating the inner and outer cylindrical cavities and defined by a ridge having an inner annular surface facing the inner cylindrical cavity, and the pressing step comprises moving an end of the outer electrical conductor into the inner cavity and into engagement with the inner annular surface. These steps simplify production of the assembly.
- According to still other method features, the inner electrical conductor and the adapter are made of stainless steel and are plated before the pressing step. The use of plated stainless steel facilitates both hermetic sealing and soldering of the inner conductor and adapter while performing the plating step before insertion of the outer conductor reduces plating costs and minimizes the addition of undesirable magnetic properties to the assembly.
- These and other objects and features of the invention will become more apparent upon a perusal of the following description taken in conjunction with the accompanying drawings wherein:
- Fig. 1 is a right perspective view of an hermetically sealed electrical feedthrough assembly according to the invention;
- Fig. 2 is a left perspective view of the assembly shown in Fig. 1;
- Fig. 3 is a sectional view taken along the lines 3-3 of Fig. 1;
- Fig. 4 is a right end view of the assembly shown in Fig. 1; and
- Fig. 5 is a left end view of the assembly shown in Fig. 1.
- A preferred embodiment of an electrical feedthrough assembly 11 is illustrated in Figs. 1-5. Included in the assembly 11 are a
metal adapter 12 and acylindrical glass body 13 and acoaxial cable 14 both retained thereby. Theadapter 12 has an outercylindrical portion 15 joined to an innercylindrical portion 16 of reduced diameter and both axially aligned with thecoaxial cable 14. Projecting outwardly from the outercylindrical portion 15 is acircumferential flange 17 that defines anannular surface 18 facing toward thecoaxial cable 14. Further defined by the outercylindrical portion 15 is an outercylindrical cavity 19 that retains and conforms in shape to theglass body 13, which also is axially aligned with thecable 14. Theglass body 13 is hermetically sealed within the outercylindrical cavity 19 of theadapter 12 and defines anaxial passage 21. - Forming the
coaxial cable 14 is an elongated innerelectrical conductor 22 and an elongated and coaxial, tubular outerelectrical conductor 23 separated therefrom by an annular space filled with anelectrical insulation material 24. Onelength portion 25 of theinner conductor 22 adjacent to afirst end 26 thereof is received by and hermetically sealed in theaxial passage 21 of theglass body 13. Anotherlength portion 28 of theinner conductor 22 between asecond end 29 thereof and the onelength portion 25 is received by acentral passage 31 in theelectrical insulation 24. Electrically connected to theadapter 12 bysolder 32 is oneend portion 33 of theouter conductor 23 while anopposite end portion 34 terminates adjacent to thesecond end 29 of theinner conductor 22. - An inner
cylindrical cavity 35 is formed in the reduced diameterinner portion 16 of theadapter 12. Theinner cavity 35 is axially aligned with theouter cavity 19 and is separated therefrom by acentral cavity 36 defined by an inwardly directed annular rib 37 projecting inwardly from theouter portion 15 of theadapter 12. Defined by the annular rib 37 is anouter shoulder surface 38 engaged by theglass body 13 and aninner shoulder surface 39. Anend section 41 of the oneend portion 33 of theouter conductor 23 conforms in shape to and is received by the innercylindrical cavity 35. Engaging theinner shoulder surface 39 of the annular rib 37 is an end 42 of theend section 41. - According to a preferred embodiment of the assembly 11, the
adapter 12 and theinner conductor 22 are made of stainless steel plated with a nickel, gold alloy; theouter conductor 23 is made of ductile, electrically conductive material such as copper; and theelectrical insulation 24 is a suitable dielectric. In typical use, theouter portion 15 of theadapter 12 is inserted through anopening 44 in ahousing 45 to produce engagement thereof with theannular surface 18 on thecircumferential flange 17. A hermetic seal then is established between thehousing 45 and theadapter 12 bysolder 46 applied between thehousing 45 and thecircumferential flange 17. Thesecond end 29 of theinner conductor 22 and theopposite end portion 34 of theouter conductor 23 then are electrically connected to circuity (not shown) to be hermetically sealed within thehousing 45. A conventional female socket connector then can be coupled to thefirst end 26 of theinner conductor 22 so as to provide for the transmission of electrical signals through the walls of thehousing 45. - In accordance with a preferred method of construction for the assembly 11, the
length portion 25 of theinner conductor 22 is inserted into theaxial passage 21 of theglass body 13 which then is inserted into the outercylindrical cavity 19 of theadapter 12. Sequential heating and cooling produces non-uniform expansion of theglass body 13 relative to the stainless steelinner conductor 22 andadapter 12 and resultant compression therebetween that creates an hermetic seal. After the sealing step, the exposed surfaces of theinner conductor 22 and theadapter 12 are plated with a nickel, gold alloy. The gold in the plating finish enhances the electrical conductivity of theinner conductor 22 and theadapter 12 so as to reduce the RF insertion losses of the completed cable assembly 11, while the nickel content both facilitates subsequent soldering operations on theadapter 12 and functions as a barrier to prevent the migration of contaminants through the gold and nickel layer. Next, the previously combinedouter conductor 23 andinsulation 24 are assembled as a composite body by pressing thelength portion 28 of theinner conductor 22 into thecentral passage 31. During this assembly step, theend section 41 of theouter conductor 23 is inserted into the innercylindrical cavity 35 of theadapter 12 until the end 42 of theouter conductor 23 engages theinner surface 39 of the rib 37. Finally, theouter conductor 23 is secured to theadapter 12 by the application ofsolder 32 therebetween.
Claims (10)
- An hermetically sealed electrical feedthrough assembly comprising an elongated inner electrical conductor (22) and having first (26) and second ends (29), a glass body (13) hermetically sealed around one length portion (25) of the inner conductor adjacent to the first end thereof, a metal adapter (12) hermetically sealed around the glass body and adapted for mounting in a wall of a housing, a tubular outer electrical conductor (23) enclosing and coaxial with another length portion (28) of the inner electrical conductor (22), the outer electrical conductor (23) being separated from the inner electrical conductor (22) by an annular volume and having one end portion (33) electrically connected to the metal adapter (12) and an opposite end portion (34) disposed adjacent to the second end (29) of the inner electrical conductor (27) and electrical insulation (24) filling the annular volume and electrically isolating the outer electrical conductor (23) from the length portion (28) of the inner electrical conductor, characterized in that the inner electrical conductor (22) and the adapter (12) are made of a substantially non-magnetic material plated with a solderable material.
- An assembly according to claim 1, characterized in that the adapter defines an outer cylindrical cavity (19) extending inwardly from an outer end thereof and an inner cylindrical cavity (35) extending inwardly from an inner end thereof and coaxially aligned with the outer cylindrical cavity, the outer cylindrical cavity (19) retaining the glass body (13) and the inner cylindrical cavity (35) retaining an end section (41) of the outer electrical conductor (23).
- An assembly according to claim 2, characterized in that the inner and outer cylindrical cavities (19, 35) are separated by a central cavity (36) defined by a projection (37) having an inner surface (39) facing the inner cylindrical cavity (35) and an outer surface (38) facing the outer cylindrical cavity (19) and wherein the inner surface (39) engages the outer electrical conductor (23) and the outer surface (38) engages the glass body (13).
- An assembly according to claim 3, characterized in that the projection (37) comprises an annular rib (37).
- An assembly according to claim 4, characterized in that the diameter of the inner cylindrical cavity (35) is less than the diameter of the outer cylindrical cavity (19).
- An assembly according to claim 5, characterized in that the length portion (28) of the inner electrical conductor (22) extends between the second end (29) thereof and the central cavity (36).
- An assembly according to claim 6, characterized in that the inner electrical conductor (22) and the adapter (12) are made of stainless steel and plated with an alloy comprising nickel and gold.
- An assembly according to claim 7, characterized in that the outer electrical conductor (23) is made of a ductile, electrically conductive material.
- An assembly according to claim 1, characterized in that the adapter (12) is one-piece and defines a circumferential flange (17) with an annular surface (18) for engaging the wall of the housing, the annular surface facing toward the second end (29).
- A method for producing an hermetically sealed electrical feedthrough assembly and comprisng the steps of providing a cylindrical glass body (13) with an axial passage (21), providing a substantially non-magnetic metal adapter (12) with an outer cylindrical cavity (19) extending inwardly from an outer end thereof and conforming to the glass body, providing an elongated substantially non-magnetic inner electrical conductor (22), providing an elongated, tubular outer electrical conductor (23) having an inner surface engaged by an elongated cylindrical insulator (24) defining a central passage (31) coaxially aligned with the outer electrical conductor and conforming in shape to the inner electrical conductor, inserting one length portion (25) of the inner electrical conductor (22) into the axial passage (21), inserting the glass body (13) into the outer cylindrical cavity (19), applying heat so as to produce a hermetic seal between the glass body (13) and both the adapter (12) and the length portion (25) of the inner electrical conductor (22), plating exposed portions of the adapter (12) and inner electrical conductor (22) with a solderable material, subsequently pressing another length portion (28) of the inner electrical conductor (22) into the central passage (31) and electrically connecting the outer electrical conductor (23) to the adapter (12).
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US06/897,654 US4737601A (en) | 1986-08-18 | 1986-08-18 | Hermetically sealed electrical feedthrough and method of making same |
DE8787308514T DE3776908D1 (en) | 1987-09-25 | 1987-09-25 | HERMETICALLY SEALED ELECTRICAL ENTRY. |
EP19870308514 EP0308557B1 (en) | 1987-09-25 | 1987-09-25 | Hermetically sealed electrical feedthrough |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP19870308514 EP0308557B1 (en) | 1987-09-25 | 1987-09-25 | Hermetically sealed electrical feedthrough |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0308557A1 EP0308557A1 (en) | 1989-03-29 |
EP0308557B1 true EP0308557B1 (en) | 1992-02-26 |
Family
ID=8198046
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19870308514 Expired - Lifetime EP0308557B1 (en) | 1986-08-18 | 1987-09-25 | Hermetically sealed electrical feedthrough |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0308557B1 (en) |
DE (1) | DE3776908D1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11485670B2 (en) | 2013-10-10 | 2022-11-01 | Medtronic, Inc. | Hermetic conductive feedthroughs for a semiconductor wafer |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0758800B1 (en) * | 1995-08-10 | 1999-10-20 | Emerson Electric Co. | Method of manufacturing lid covers for containers and product |
DE102017000361A1 (en) * | 2017-01-17 | 2018-07-19 | Liebherr-Elektronik Gmbh | High-pressure bushing for carrying a coaxial cable into a high pressure area |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
BE788766A (en) * | 1971-09-23 | 1973-01-02 | Bunker Ramo | ELECTRICAL PASS-THROUGH ASSEMBLIES |
GB1571792A (en) * | 1975-11-19 | 1980-07-16 | Bunker Ramo | Interconnector |
GB2029651B (en) * | 1978-09-07 | 1982-11-10 | Standard Telephones Cables Ltd | Demountable connectors for submarine repeaters |
US4420210A (en) * | 1981-09-17 | 1983-12-13 | The Bendix Corporation | Hermetic through bulkhead electrical connector |
FR2591040B1 (en) * | 1985-11-29 | 1988-01-22 | Radiall Ind | HERMETIC COAXIAL CONNECTOR |
-
1987
- 1987-09-25 DE DE8787308514T patent/DE3776908D1/en not_active Expired - Fee Related
- 1987-09-25 EP EP19870308514 patent/EP0308557B1/en not_active Expired - Lifetime
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US11485670B2 (en) | 2013-10-10 | 2022-11-01 | Medtronic, Inc. | Hermetic conductive feedthroughs for a semiconductor wafer |
Also Published As
Publication number | Publication date |
---|---|
EP0308557A1 (en) | 1989-03-29 |
DE3776908D1 (en) | 1992-04-02 |
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