Feedthrough assembly of airtightly sealed and controlled impedance

Abstract

To provide an assembly for delivering an electric signal of a controlled impedance between two different environments through feedthrough of a feedthrough block.SOLUTION: A feedthrough 11 has a signal coupling part 61, a dielectric body 53 surrounding the signal coupling part 61, and a ground coupling part 70 surrounding the dielectric body 53. An electric insulation block 30 has a conductive signal link 62, and a separate conductive ground link 71 surrounding the signal link 62. A conductive block has a separate dielectric spacer, and a signal link 62 passing through the spacer. Coupling parts among the block 30, the links 62 and 71 and the spacers are sealed, and airtightly separate two environments. One method press-fits components, and forms no gap between the adjacent components. Another method forcibly puts a potting material into the coupling parts between the components.SELECTED DRAWING: Figure 18

Description

[Technical field]

[0001] The present invention relates to electrical cable feedthrough assemblies, and more particularly to controlled impedance cable feedthroughs that are typically used to transmit high frequency signals between different physical environments. [Background technology]

[0002] In some situations, signals must be sent between different environments, for example between environments with different atmospheric gases, between environments at different atmospheric pressures, between environments with different sterility levels, etc. In such cases, the interfaces must be hermetically sealed to prevent the environments from mixing or one environment from contaminating the other.

[0003] In the current state of the art, individual coaxial connectors such as SMA or SMP are used to transmit signals between environments. These connectors are fairly large, 0.25 to 0.5 inches in diameter. Because they cannot be brought closer than their maximum diameter, the number of connectors per unit area separating the environments, i.e., the density, is fairly small. Summary of the Invention [Problem to be solved by the invention]

[0004] This specification describes an assembly for passing signals between two different environments. Those signals, typically RF, pass through a first connector in the first environment, through a feedthrough in a flange that separates the two environments, and through a second connector in the second environment. Each connector terminates with one or more controlled impedance cables. [Means for solving the problem]

[0005] The connector has several embodiments, representative of which include an anchor block for securing the cable, compliant signal contacts for making the electrical connection between the cable signal conductors and the feedthrough, and optionally compliant ground contacts for making the electrical connection between the cable shield and the feedthrough, and a plate attached to the anchor block 88 that holds the contacts.

[0006] The conductive anchor block provides a common ground for the cables that are either permanently or removably attached to the anchor block. Alternatively, the anchor block is non-conductive and only provides an anchor for the removably attached cables 20.

[0007] The connector can be designed for use with contacts conforming to any number of different standards. A plate holds the contacts. The plate can be constructed of an electrically conductive or electrically insulating material. The plate abuts the anchor block face 92 when the connector is assembled and typically abuts the feedthrough block when the connector is connected to the feedthrough block. The signal contacts are captured within through apertures in the plate. If the plate is conductive, the signal contacts are insulated from the plate. Prior to assembly of the plate into the anchor block, contact points of the signal contacts extend from each side of the plate. Each ground contact is captured within a ground through aperture. Prior to assembly of the plate into the anchor block, contact points of the ground contacts extend from each side of the plate.

[0008] The signal travels through the flange via a feedthrough in a feedthrough block. The feedthrough has three components: a signal coupling section, a dielectric that surrounds the signal coupling section, and a ground coupling section that surrounds the dielectric. If the block is electrically insulating, the block itself can act as the dielectric. If the block is conductive, another dielectric is required.

[0009] Another dielectric-free feedthrough has a signal through aperture in the block for a signal link, which is a conductive wire or pin. Both ends of the signal link are contact points for the signal contacts of the connector. Optionally, the signal link and signal aperture are shaped to prevent the signal link from being forced through the signal aperture during set-up or when the first environment is at a higher pressure than the second environment.

[0010] The feedthrough with another dielectric has a spacer through an aperture in the block with the dielectric in the form of a dielectric spacer. Optionally, the spacer aperture and the spacer are shaped to prevent the spacer from being forced through the spacer aperture during set-up or when the first environment is at a higher pressure than the second environment. The spacer has a signal through aperture for the signal link.

[0011] In general, the apertures, spacers, and signal links are sized to provide a matched impedance for the signal using methods known in the art. For accurate impedance matching, the dielectric must be surrounded by the ground plane of the system. If the block is conductive, no special containment is required for the ground signal. Non-conductive blocks must route the ground signal through the block by a ground bond.

[0012] The ground coupling may include a separate conductive ground link that extends through a ground aperture in the block. An appropriate number of ground links surround the signal link. The ground link is a conductive wire or pin. Alternatively, the ground link is a plated tube. In another configuration, the ground coupling is a conductive ground ferrule set in a through aperture of a ground ferrule in the block surrounding the spacer. In another configuration, the walls of the spacer aperture are coated with a conductive material.

[0013] The various components are configured with hermetic seals to hermetically separate the two environments. In one method, the various components are press-fit into corresponding apertures, leaving no air gaps between adjacent components.

[0014] In another method, the spacer is shorter than the spacer apertures so that one or both sides of the spacer are recessed from the corresponding block surface, thereby leaving a gap between the spacer and the block surface. One or both of the gaps are potted to seal around the spacer apertures and the signal links, thereby creating a hermetic seal. A typical potting material is a two-part epoxy. The minimum depth of each gap depends on the environment and the potting material, and is typically 0.01 inches or greater. The plated tubes are hermetically sealed by filling them with potting material or by soldering.

[0015] One method of potting involves applying a vacuum to one surface of the block, which allows the potting material to be pulled from the other side, thereby forcing the potting material into voids and interfaces between all components. This vacuum ensures that the potting material is forced into all spaces that may provide leak paths. Alternatively, pressure is applied at one surface, forcing the potting material into all spaces that may provide leak paths.

[0016] The present invention contemplates that the flange is a block, i.e., the feedthroughs extend through the flange itself. Alternatively, the block is a separate component that is hermetically sealed within an opening in the flange.

[0017] The objectives of the present invention will become apparent upon consideration of the following drawings and detailed description of the invention.

[0018] For a more complete understanding of the nature and objects of the present invention, reference is made to the accompanying drawings. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view of one embodiment. [Diagram 2] FIG. 2 is a detailed view of FIG. [Diagram 3] FIG. 2 is a cross-sectional view of a portion of the connector configuration of FIG. 1 with a permanently attached cable. [Figure 4] FIG. 13 is a cross-sectional view of a portion of a connector configuration with a detachable cable. [Diagram 5] FIG. 13 is a cross-sectional view of a portion of another configuration of a connector with a detachable cable. [Figure 6] FIG. 13 is a cross-sectional view of a portion of another configuration of a connector with a detachable cable. [Figure 7] FIG. 13 is a cross-sectional view of one configuration of the plate along with a portion of the anchor block and cable. [Figure 8] FIG. 13 is a cross-sectional view of another configuration of the plate with a portion of the anchor block and cable. [Figure 9] FIG. 13 is a cross-sectional view of an insulating plate with fuzz button contacts. [Figure 10] FIG. 2 is a cross-sectional view of an insulating plate with conductive rubber contacts. [Figure 11] FIG. 11 is a cross-sectional view taken along line EE in FIG. [Figure 12] FIG. 12 is a cross-sectional view taken along line FF in FIG. [Figure 13] FIG. 13 is a bottom view of an insulating plate with embedded, stamped or etched contacts. [Figure 14] FIG. 13H is a detailed view of the bottom of the coax cable termination assembly. [Figure 15] FIG. 14 is a cross-sectional view of the plate of FIG. 13. [Figure 16] FIG. 13 is a cross-sectional view of an insulating plate with embedded stamped or etched contacts, one side of the contacts conforming to a cable and the contacts compressed. [Figure 17]FIG. 13 is a cross-sectional view of the block separated from the flange. [Figure 18] FIG. 2 is a cross-sectional view of a basic feedthrough without a separate dielectric. [Figure 19] FIG. 19 is a top view of the feedthrough of FIG. 18. [Figure 20] 11A-11C are cross-sectional views of a feedthrough with alternative configurations of signal links and signal apertures. [Figure 21] 11A-11C are cross-sectional views of a feedthrough with alternative configurations of signal links and signal apertures. [Figure 22] FIG. 1 is a cross-sectional view of a basic feedthrough. [Diagram 23] FIG. 23 is a top view of the feedthrough of FIG. 22. [Figure 24] 1 is a cross-sectional view of a feedthrough with an alternative configuration of some components. [Diagram 25] FIG. 25 is a top view of the feedthrough of FIG. 24. [Figure 26] 1 is a cross-sectional view of a feedthrough with an alternative configuration of some components. [Figure 27] 1 is a cross-sectional view of a feedthrough with an alternative configuration of some components. [Figure 28] FIG. 2 is a cross-sectional view of a feedthrough with a ground link. [Figure 29] FIG. 1 is a top view of a feedthrough with a signal link and a ground link surrounding a spacer. [Diagram 30] FIG. 1 is a cross-sectional view of a PCB block with a ground link. [Diagram 31] FIG. 1 is a top view of the feedthrough with a ground link for the ground plane. [Diagram 32] FIG. 2 is a cross-sectional view of a feedthrough with a ground ferrule. [Diagram 33] FIG. 2 is a cross-sectional view of a feedthrough with a plated aperture and a ground pad. [Diagram 34] FIG. 2 is a cross-sectional view of a block that is a part of the flange. [Diagram 35] FIG. 2 is a top view of the flange as a block. [Diagram 36] FIG. 13 is a top view of a flange with a separate block. [Figure 37] FIG. 13 is a top view of the flange with the PCB as a block. [Figure 38] FIG. 2 is a cross-sectional view showing the connection of a connector to a feed-through block. [Figure 39] FIG. 13 is a cross-sectional view of another embodiment. [Diagram 40] FIG. 40 is a cross-sectional view of the embodiment of FIG. 39 with a connector attached. [Diagram 41] 40 is another cross-sectional view of the embodiment of FIG. 39 with a connector attached. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] This specification describes an assembly 10 for passing signals between a first environment 1 and a second environment 2 separated by a barrier 3. The two environments 1, 2 may differ in many ways. For example, there may be pressures, temperatures, or chemical compounds on either side of the barrier 3 that do not mix in some applications. An example of such a situation is passing data into and out of a cryogenic computing environment, such as a quantum computing environment. The first environment 1 is typically at normal atmospheric pressure and room temperature. In a quantum computing environment, the second environment 2 is an almost perfect vacuum. The region of the second environment 2 closest to the first environment 1 is at about room temperature, and the temperature of the region furthest from the first environment 1 is kept at 4 Kelvin to 4 milliKelvin.

[0021] As shown in Figures 1 and 2, signals are passed between environments 1, 2 through a first connector 14 in the first environment 1, a flange 12 separating the two environments 1, 2, and a second connector 16 in the second environment 2. The signals are typically radio frequency or RF signals. Signal speeds can be as low as a few hundred MHz, or as high as 70 GHz, depending on the application, although the highest frequency range that the present invention can utilize is constantly improving.

[0022] Each connector 14, 16 terminates with one or more controlled impedance cables 20. A controlled impedance coaxial cable 20 has a signal conductor 22 surrounded by a dielectric 24 with a ground reference shield 26 outside the dielectric 24. Optionally, a sheath 28 covers the shield 26. A controlled impedance twinaxial cable 20 has two signal conductors 22 surrounded by a dielectric 24 with a ground reference shield 26 outside the dielectric 24 and a sheath 28 covering the shield 26. To properly terminate the cable 20, the cable's ground shield 26 must be electrically coupled to the connector 14, 16. Optionally, a ferrule 90 can be set on the ground shield 26 as in FIG. 2. Controlled impedance cables 20 with more than two signal conductors 22 are available. Although not specifically described, the present invention can be adapted to accommodate cables 20 with any number of signal conductors 22.

[0023] The flange 12 is removably mounted within an opening in a barrier 3 separating the two environments 1, 2. The flange 12 may be mounted in any manner that provides an acceptable hermetic seal between the flange 12 and the barrier 3. Attachment methods are known in the industry. Alternatively, the barrier 3 incorporates the flange 12, i.e. the barrier 3 and the flange 12 are not separate components.

[0024] Signals travel through the flange 12 via the feedthrough 11 in the feedthrough block 30. Connectors 14, 16 provide an interface between a controlled impedance coaxial cable (hereafter simply "cable") 20 and the feedthrough 11. Various configurations of connectors 14, 16 are described in U.S. Patent Nos. 8,926,342 and 9,160,151, both of which are incorporated herein by reference. Some of the configurations are summarized below. Only one connector 14 is referenced hereinafter.

[0025] The connector 14 has several embodiments, representative of which include an anchor block 88 for securing the cable 20, standard compliant signal contacts 86 for making an electrical connection between the cable signal conductors 22 and the feedthrough 11, an optional standard compliant ground contact 87 for making an electrical connection between the cable shield 26 and the feedthrough 11, and a plate 89 attached to the anchor block 88 that holds the contacts 86, 87.

[0026] In one configuration, anchor block 88 is conductive and provides a common ground for the permanently attached cables 20 as in Figure 3. The ground shields 26 of all of the cables 20 are electrically connected to anchor block 88 at holes 91 in anchor block 88. Any suitable method may be used, including soldering, crimping, potting with a conductive adhesive, insert molding anchor block 88 with the cables 20 in place during molding, and pressing ground shields 26, e.g., pre-tinned and hardened, into holes 91.

[0027] Once the cable 20 is anchored in the anchor block 88, the face 92 of the anchor block 88, the signal conductors 22, and the dielectric 24 are properly prepared to make reliable electrical contact with the standard compliant contacts 86, 87. The anchor block face 92, the signal conductors 22, and the dielectric 24 may require polishing and flattening by some mechanical means, such as milling, grinding, or sanding, so that the cable center conductor 22 and the dielectric 24 are positioned at a known depth relative to, and in this case flush with, the anchor block face 92. The anchor block face 92 and the signal conductors 22 may also require precious metal plating to protect the polished surfaces from oxidation that would otherwise deteriorate and prevent acceptable electrical connection of the contacts 86, 87 to the signal conductors 22 and the anchor block 88.

[0028] In alternative configurations, anchor blocks 88 are either conductive or non-conductive, merely providing anchors for removably attached cables 20. Methods for removably attaching cables 20 to anchor blocks 88 are shown in Figures 4-6. These methods allow for replacement of individual cables 20, thus avoiding the need to replace the entire assembly.

[0029] The first method, shown in FIG. 4, entails attaching a ferrule to or near the end of the cable 20 to trim the cable end. The sheath 28 is stripped and a threaded ferrule 94 is placed over the shield 26. The ferrule 94 is attached to the cable 20 by soldering, crimping, or other mechanical means to electrically couple the ferrule 94 to the shield 26. The ferrule face 95, signal conductor 22, and dielectric 24 are then trimmed as described above relative to the anchor block 88. The ferrule 94 is threaded through a threaded hole 96 in the anchor block 88 until the signal conductor 22 is pressed against the signal contact 86 to create an electrical connection between the signal conductor 22 and the signal contact 86.

[0030] A second method for removably attaching the cable 20 to the anchor block 88 involves the use of a twist-lock coupling 100 as shown in FIG. 5. A twist-lock component 102 is placed over the cable 20, allowing the component 102 to slide freely over the cable 20. A coil spring 104 is placed over the cable 20. After the sheath 28 is stripped, a ferrule 106 is attached to the shield 26 by soldering, crimping, or other mechanical means to electrically couple the ferrule 106 to the shield 26. The ferrule face 108, signal conductors 22, and dielectric 24 are then aligned relative to the anchor block 88 as described above.

[0031] The ferrule 106 / cable 20 is inserted into a hole 110 in the anchor block 88. A protrusion 112 from the twist-lock component 102 slides down into an opposing notch (not shown) in the side of the hole 110 until it aligns with a tubular recess 114 in the hole 110. This alignment causes the spring 104 to compress to urge the signal conductor 22 up to the signal contact 86 to create an electrical connection between the signal conductor 22 and the signal contact 86. The twist-lock component 102 is engaged with the protrusion 112 captured in the tubular recess 114, thereby retaining the cable 20 in the hole 110.

[0032] Another method of removably mounting the cable 20 to the anchor block 88 is shown in FIG. 6. A ferrule 120 is mounted to the cable 20 and trimmed as described above. The ferrule 120 has a tubular ridge 122 at or away from the end 124 of the ferrule 120 as in FIG. 6. The anchor block 88 has two sections, a bottom section 126 and a top section 128. The top end of the cable lumen 130 in the bottom section 126 has a tubular groove 132. When the ferrule 120 / cable 20 assembly is inserted into the cable lumen 130, the ridge 122 fits into the groove 132 flush with the block face 92, along with the ferrule face 134, the signal conductor 22, and the dielectric 24. The top section 128 of the block is set into the bottom section 126 and attached by screws, clips, or any other acceptable method. The top section 126 captures the ferrule 120 / cable 20 assembly in the anchor block 88. Optionally, the ridges 122 and grooves 132 can be adjusted to prevent the ferrule 120 / cable 20 assembly from rotating within the cable lumen 130.

[0033] In some situations, particularly involving removable coupling devices, the signal conductor 22 and / or dielectric 24 may not be exactly flush with the anchor block face 92, i.e., may recess or protrude slightly into the anchor block face 92. This recess or protrusion may be on the order of 0.05 inches. This specification and claims use the term "flush" to indicate that the signal conductor 22 and dielectric 24 are substantially flush, recessing or protruding slightly into the anchor block face 92 by on the order of 0.05 inches.

[0034] The connector 14 can be designed for use with any number of different standard compliant contacts, including, but not limited to, skewed coil contacts, fuzz button contacts, conductive rubber contacts, and conductive strip contacts. Figures 3-8 show a connector designed for use with skewed coil contacts. Skewed coil contacts of various types and configurations are described in U.S. Patent Nos. 7,126,062 and Re 41,663, both of which are incorporated herein by reference. Briefly, skewed coil contacts include an essentially flexible wire with a pair of conductive, oppositely extending leads. These leads extend in an angled direction from the coil axis. During compression, the coil loops are electrically shorted together while sliding along one another.

[0035] Plate 89, shown in Figures 7 and 8, carries contacts 86, 87 and may be constructed of an electrically conductive or an electrically insulating material.

[0036] Plate 89 has a block surface 154 that abuts anchor block surface 92 when connector 14 is assembled, and a feedthrough surface 156 that generally abuts feedthrough block 30 when connector 14 is connected to feedthrough block 30. Generally, plate 89 is attached to anchor block surface 92 by screws 216.

[0037] 7, the signal contact 86 is captured in a through aperture 160 in the plate 89. The signal through aperture 160 has a larger central section 166 that narrows to a smaller signal block opening 168 in the block face 154 and a smaller signal feedthrough opening 170 in the feedthrough face 156. The coil 140 of the contact 86 is captured in the central section 166. Prior to assembly of the plate 89 into the anchor block 88, the block contact points 142 of the signal contact 86 extend from the signal block opening 168. Prior to connecting the connector 14 to the feedthrough block 30, the feedthrough contact points 144 of the signal contact 86 extend from the signal feedthrough opening 170.

[0038] If plate 89 is conductive, signal through aperture 160 resides in an insulating plug 162 that prevents signal contact 86 from electrically shorting to plate 89. Plug 162 is typically made from an insulating plastic. Plug 162 fits into a signal through hole 164 in plate 89.

[0039] After the plate 89 is assembled to the anchor block 88 , each signal block opening 168 is aligned with a corresponding cable 91 in the anchor block 88 .

[0040] Each ground contact 87 is captured within a ground through aperture 190. Each ground through aperture 190 has a larger central section 192 that narrows to a smaller ground block opening 194 in the block face 154 and a smaller ground feedthrough opening 196 in the feedthrough face 156. The coil 146 of the ground contact 87 is captured within the central section 192. Prior to assembly of the plate 89 to the anchor block 88, the block contact points 148 of the ground contact 87 extend from the ground block openings 194. Prior to connecting the connector 14 to the feedthrough block 30, the feedthrough contact points 150 of the ground contact 87 extend from the ground feedthrough openings 196.

[0041] If constructed of a conductive material, plate 89 electrically couples with ground contact 87 , thereby providing a more accurate impedance match to signal contact 86 .

[0042] 7 configuration, plate 89 has two mirror image sheets 200, 202. The bottom sheet 200 has the feedthrough openings 170, 196 and half of the central sections 166, 192, and the top sheet 202 has the block openings 168, 194 and half of the central sections 166, 192. The contacts 86, 87 are placed in the central section 166, 192 of one sheet 200 and the sheets 200, 202 are sandwiched together to capture the contacts 86, 87.

[0043] 8, plate 89 has a bottom sheet 204 with the feedthrough openings 170, 196 and the entire central section 166, 192, and a top sheet 206 with only the block opening 168. The contacts 86, 87 are mounted in the central section 166, 192 of the bottom sheet 204, and the sheets 204, 206 are sandwiched together to encase the contacts 86, 87.

[0044] If an insulating plug 162 is used, it may be press-fit into the through hole 164 of the plate 89 or may be bonded into the through hole 164 with an adhesive. Alternatively, as shown in FIG. 7, the plug 162 has two parts 174, 176, each of which fits into one plate sheet 200, 202. Mating shoulders 178, 180 hold the plug parts 174, 176 to the plate sheets 200, 202. Alternatively, as shown in FIG. 8, the plug 162 has a lower portion 182 and an upper portion 184, which fit into a lower sheet 204 and an upper sheet 206, respectively. Mating shoulders 186, 188 hold the plug parts 182, 184 to the plate sheets 204, 206.

[0045] As discussed above, fuzz button contacts may be utilized. As shown in Figure 9, fuzz button contact 220 is cylindrical. Plate 89 has aperture 160 therethrough, such as 224, which is narrower in the middle than at the ends. Contact 220 is forced into aperture 160. The length of contact 220 is such that end 226 extends from plate 89.

[0046] As discussed above, conductive rubber contacts may be utilized. As shown in Figures 10-12, the conductive rubber contacts 230 for the signal contacts 86 may be cylindrical with a centrally located tubular recess 232. The plate 89 has a through aperture 160 with a centrally located tubular protrusion 236. The conductive rubber 30 is radially compressed and seated within the aperture 160, whereby the protrusion 236 fits within the recess 232 to hold the contacts 230 within the aperture 160. The length of the contacts 230 is such that both ends 238 extend from the plate 89.

[0047] The conductive rubber contacts for the ground contacts 87 can be of the same structure as the signal contacts 86. Alternatively, the conductive rubber contacts 242 for the ground contacts 87 are circular and surround the signal contacts 86, as in FIG. 11. The conductive rubber contacts 242 have a circular top sheet 244 adjacent to the anchor block 88 and a circular bottom sheet 246 for interfacing to the feedthrough block 30. The two sheets 244, 246 are electrically connected to through apertures 250 in the plate 89 by a number of plugs 248. The number of plugs 248 can vary depending on the application, and is typically four or eight, evenly spaced around the signal contacts 230. To accompany the signal contacts 230, each plug 248 has a tubular recess 252 that fits into a tubular protrusion 254 for retention. As shown in FIG. 12, knobs 256 extend from the seats 244, 246 into recesses 252 in the plate 89 to help hold the seats 244, 246 in place.

[0048] As mentioned above, conductive strip contacts can be utilized. In Figs. 13-16, contact 270 is a strip of conductive material in a C-shape. The contacts can be formed by chemical etching, stamping and molding, or any other practical means. Signal contacts 270 are captured in through apertures 160 in plate 89. In their resting state, contact leads 272 extend outside plate 89, Fig. 15. When anchor block 88 is attached to plate 89, top lead 272 deforms into recess 276 toward plate 89, Fig. 16, thereby providing electrical contact to signal conductor 22 by signal contact 86 and to anchor block 88 by ground contact 87. When the assembly is connected to feedthrough block 30, bottom lead 274 deforms into recess 278 toward plate 89.

[0049] As mentioned above, signals travel through the flange 12 via the feedthrough 11 in the feedthrough block 30 as shown in Figures 1, 2, 17 and 34. A first surface 38 of the block 30 is designed to accommodate a first environment 1 and a second surface 40 of the block 30 is designed to accommodate a second environment 2.

[0050] The feedthrough block 30 has a feedthrough 11 for each signal passing between the two environments 1, 2 through a flange 12. To accurately pass signals with controlled impedance, the feedthrough 11 requires at least three components: a signal coupling portion 61, a dielectric 53 surrounding the signal coupling portion 61, and a ground coupling portion 70 surrounding the dielectric 53.

[0051] The feedthrough 11 has two different configurations, which differ based on the material that the block 30 is made of. If the block 30 is made of an electrically insulating material, the block 30 itself can act as the dielectric 53. If the block 30 is made of a conductive material, a separate dielectric 53 is required.

[0052] Another dielectric-free feedthrough 11 is shown in Figures 18 and 19. The feedthrough 11 has a signal through aperture 43 in the block 30 that extends between a first opening 44 in the first surface 38 of the block 30 and a second opening 45 in the second surface 40 of the block 30. As shown in Figure 19, the signal through aperture 43 is generally circular, but can be other shapes.

[0053] The signal coupling portion 61 includes a signal link 62 extending through each signal aperture 43. The signal link 62 is a conductive wire or pin and may be constructed of any conductive material suitable for the application. Typically, the signal link 62 is constructed of a copper alloy. In one configuration, the signal link 62 is constructed of beryllium copper with gold plating over nickel. If a non-magnetic signal link 62 is desired, gold-plated beryllium copper may be used. The signal link 62 may also be constructed of a non-conductive material, so long as the signal link 62 is capable of conducting electricity. For example, the signal link 62 may be constructed of a non-conductive plastic or composite material embedded in or coated with a conductive material that provides electrical conductivity to the signal link 62.

[0054] The signal link 62 has a first end 65 on the first surface 38 of the block and a second end 66 on the second surface 40 of the block. The ends 65, 66 of the signal link are contact points for the signal contacts 86 of the connectors 14, 16. Optionally, the ends 65, 66 are flush with the corresponding block surfaces 38, 40. Due to imprecision and tolerances in the manufacturing process, the ends 65, 66 of the signal link may not be exactly flush with the corresponding block surfaces 38, 40; that is, they may be slightly recessed or protruding into the corresponding block surfaces 38, 40. Typically, the recess is 0.0005 inches or less and the protrusion is 0.001 inches or less, but may be as much as 0.05 inches. If the protrusion or recess is greater than the tolerance, the affected signal link ends 65, 66 and corresponding block surfaces 38, 40 can be polished and flattened by some mechanical means such as milling, grinding, or sanding to ensure that the signal link ends 65, 66 are a known depth relative to the block surfaces 38, 40, in this case flush with the ground block face 20. The polished ends 65, 66 may also require precious metal plating to prevent them from oxidizing or otherwise deteriorating and preventing an acceptable electrical connection.

[0055] As used herein and in the claims, the term "flush" indicates that both signal link ends 65, 66 are substantially flush with each other, recessing or protruding slightly into the corresponding block surfaces 38, 40 by approximately 0.05 inches.

[0056] The signal link 62 has a cross-sectional shape that allows it to properly match, both mechanically and electrically, to the signal aperture 43. In the drawings, the signal aperture 43 and the signal link 62 are both circular. However, the signal aperture 43 and the signal link 62 can be different cross-sectional shapes as long as the joint is structurally sound. For example, the signal aperture 43 can be circular and the signal link 62 can be octagonal.

[0057] Optionally, the signal link 62 and the signal aperture 43 are shaped to prevent the signal link 62 from being forced through the signal aperture 43 during set up or when the first environment 1 is at a higher pressure than the second environment 2. Generally, the diameter of the first end 65 of the signal link is larger than the diameter of the signal aperture 43. In one configuration shown in FIG. 20, the first end 65 of the signal link has a head 63 that has a larger diameter than the remainder of the signal link 62 and the signal aperture 43. In another configuration shown in FIG. 21, the signal link 62 is frusto-conical rather than cylindrical. The signal aperture 43 is shaped to mate such that when the signal link 62 is firmly within the signal aperture 43, each end 65, 66 rests on a corresponding block surface 38, 40. Any other geometry that prevents the signal link 62 from being forced through the signal aperture 43 is contemplated by the present invention.

[0058] Ground coupling 70 is described below.

[0059] As indicated above, if the block 30 is made of an electrically conductive material, then a separate dielectric 53 is required, as shown in Figures 22 to 25. The separate dielectric 53 can also be used if the block 30 is made of an electrically insulating material that does not have the required dielectric properties.

[0060] The feedthrough 11 has a spacer through aperture 32 in the block 30 that extends between a first opening 34 in a first surface 38 of the block 30 and a second opening 36 in a second surface 40 of the block 30. As shown in Figures 23 and 25, the spacer through aperture 32 is generally cylindrical, but can be other shapes.

[0061] Within the spacer through aperture is a dielectric 53 in the form of a dielectric spacer 54. The spacer 54 has a cross-sectional shape that can adequately match the spacer aperture 32, both mechanically and electrically. In the drawings, the spacer aperture 32 and the spacer 54 are both circular. However, the spacer aperture 32 and the spacer 54 can be of different cross-sectional shapes, so long as the spacer 54 has an appropriate impedance and is structurally sound. For example, the spacer aperture 32 can be circular and the spacer 54 can be octagonal.

[0062] Optionally, the spacer aperture 32 and the spacer 54 are shaped to prevent the spacer 54 from being forced through the spacer aperture 32 during set up or when the first environment 1 is at a higher pressure than the second environment 2. Typically, the first surface 54 of the spacer 54 is larger than the second opening 36 of the spacer aperture 32. In one configuration shown in FIG. 24, the spacer aperture 32 has a stepped diameter, such as 48, to provide a shoulder 49. The spacer 54 abuts against the shoulder 49 to prevent the spacer 54 from dropping or being forced through the spacer aperture 32. In another configuration, the spacer 54 is frustoconical rather than cylindrical, similar to the signal link 62 of FIG. 21. The spacer aperture 32 is shaped to mate such that when the spacer 54 is securely in the spacer aperture 32, each end 56, 57 is properly positioned against the corresponding block surface 38, 40. Any other configuration that prevents the spacers 54 from being forced through the spacer apertures 32 is contemplated by the present invention.

[0063] The material from which the spacer 54 is made is selected depending on the application. The dielectric constant of the spacer 54 has a value required to create the desired impedance environment, typically 50 ohms, although other impedances may be desired. The dielectric constant can range from 1.1 to 15, but is typically about 3 to 4. Typically the spacer 54 is an engineered plastic (polyetheretherketone, PEEK) that is selected for its dielectric constant (Dk) value and the signal matching performance it provides. In one configuration, the Dk is 3.3, selected such that the impedance of the feedthrough is 50 ohms. Various Dk values ​​can be used depending on the desired impedance, the diameter of the aperture 32, and the diameter of the signal link 62.

[0064] The spacer 54 has one or more signal through apertures 43 that extend between a first opening 44 on a first face 56 and a second opening 45 on a second face 57 of the spacer 54. For a coaxial cable 20, there is a single signal aperture 43 axially aligned with the spacer 54. For a cable 20 with two or more signal conductors 22, the spacer 54 has a signal aperture 43 for each signal conductor 22, the signal apertures 43 being paraxially aligned and arranged for impedance matching as described below.

[0065] A signal link 62 extends through each signal aperture 43. As mentioned above, the signal link 62 is a conductive wire or pin.

[0066] As mentioned above, the signal link 62 has a first end 65 on the first surface 38 of the block and a second end 66 on the second surface 40 of the block. Optionally, both signal ends 65, 66 are flush with the corresponding block surfaces 38, 40.

[0067] As mentioned above, the signal link 62 is generally circular and may be shaped to prevent the signal link 62 from being forced through the signal aperture 43 during setup or when the first environment 1 is at a higher pressure than the second environment 2.

[0068] The remainder of this specification will be illustrated with a configuration that includes spacers 54. It will be understood that the following description also applies, mutatis mutandis, to a configuration without spacers 54.

[0069] Optionally, the aperture 32, spacer 54, and signal link 62 are sized to provide a matched impedance to the signal. Methods for doing so are known in the art, including equations, software simulators such as HFSS (High Frequency Structure Simulator). Key parameters include materials, Dk values, and dimensions.

[0070] For the feedthrough, dielectric 53 must be surrounded by the ground plane of the system to provide the correct impedance match. If block 30 is conductive, no special housing for the ground signal is needed. Block 30 itself is the contact point for ground contacts 87 of connectors 14, 16.

[0071] The non-conductive block 30 must provide a ground signal between the surfaces 38, 40 by means of a ground bond 70. This can be accomplished in a number of different ways.

[0072] In one configuration, the ground coupling 70 may include separate dielectrically conductive ground links 71 that extend through a ground aperture 72 in the block 30, as in Figures 18 and 28. The ground links 71 surround the signal links 62, such that the ground signal surrounds the spacer 54 / signal links 62, as in Figures 19 and 29. The particular number of ground links 71 used to surround the signal links 62, and their distance from the signal links 62, will be determined by the parameters of the particular application, such as the desired impedance environment, the diameter of the signal links 62 and the spacer 54, and the material from which the block 30 and the spacer 54 are constructed. The ground links 71 are generally equally spaced around a circle surrounding the aperture 32. For example, if there are six ground links 71, they will be spaced 60° apart, as at 76 in Figures 19 and 29.

[0073] The ground link 71 is a conductive wire or pin and may be constructed of any conductive material suitable for the application. Typically, the ground link 71 is constructed of a copper alloy. In one configuration, the ground link 71 is constructed of beryllium copper with gold plating over nickel. If a non-magnetic ground link 71 is desired, gold-plated beryllium copper may be used. The ground link 71 may also be constructed of a non-conductive material, so long as the ground link 71 is capable of conducting electricity. For example, the ground link 71 may be constructed of a non-conductive plastic or composite material embedded in or coated with a conductive material that provides electrical conductivity to the ground link 71.

[0074] Optionally, the ground links 71 and ground apertures 72 are shaped to prevent the ground links 71 from being forced through the ground apertures 72 during setup or when the first environment 1 is at a higher pressure than the second environment 2. The same geometries as described above with respect to the signal links 62 can be used. For example, the first end 80 of each ground link has a head 78 with a larger diameter than the remainder of the ground links 71, as shown in FIG.

[0075] When block 30 is constructed of PCB construction or other dielectric material, ground link 71 can be a plated tube 73 through block 30, such as 74 in Figure 30, to carry a ground signal through block 30. Plated tube 73 surrounds signal link 62 as described above and connects ground plane 79 to both surfaces 38, 40, generally as in Figures 30 and 31. Plated tubes 73 are hermetically sealed at 75 by filling them with a potting material such as epoxy or by soldering.

[0076] Both ends 80, 81 of the ground link are contact points for ground contacts 87 of connectors 14, 16. In the case of tube 73, plating 74 can extend horizontally along surfaces 38, 40 of the PCB to provide contact points 80, 81 for ground contacts 87.

[0077] 32, a conductive ground ferrule 64 is set in a ground ferrule through aperture 84 in the block 30, and a spacer 54 is set in a spacer aperture 32 of the ground ferrule 64, such that the ground ferrule 64 surrounds the spacer 54. A first end 82 of the ground ferrule and a first end 65 of the signal link 62 are coplanar, and a second end 83 of the ground ferrule 64 and a second end 66 of the signal link 62 are coplanar. The term (coplanar) is intended to have the same meaning as above, and the ferrule ends 82, 83 are substantially coplanar, although they may be slightly recessed or protrude into the associated block surfaces 38, 40.

[0078] The ferrule ends 82, 83 are the contact points for the ground contacts 87 of the connectors 14, 16. The ground ferrule 64 may be of a different overall height than the spacer set 54. Preferably, the ferrule faces 82, 83 and the signal link ends 65, 66 protrude beyond the corresponding block surfaces 38, 40, thereby ensuring good compressive contact with the signal contacts 86 and ground contacts 89.

[0079] In another configuration of the ground bond 70, the walls 41 of the spacer apertures 32 are coated with a conductive material. For example, if the block 30 is a PCB, the spacer apertures 32 can be plated tubes, such as 77 in FIG. 33, where the plating 77 is electrically connected to ground. The coating 77 can cover all of the walls 41 or can coat only a portion of the walls 41, such as a stripe extending between the block faces 38, 40.

[0080] Optionally, the plating 77 in the spacer apertures 32, shown in FIG. 33, may extend horizontally along the surface of the PCB to provide contact points 78 for the ground contacts 87 of the connectors 14,16.

[0081] The signal link 62, the ground bond 70, and, if utilized, the spacer 54, are set in a hermetic seal to hermetically separate the two environments 1, 2. The hermetic seal can be formed in one or more of a number of different ways.

[0082] First, the various components are press-fit into the corresponding apertures, leaving no gaps between adjacent components. For example, signal link 62 is press-fit into signal aperture 43, leaving no gaps between signal link 62 and spacer 54 or block 30. Optionally, spacer 54 is constructed of a slightly compressible material, so that when spacer 54 is set in spacer aperture 32, spacer 54 expands against spacer aperture wall 41 and against signal link 62 to form a hermetic seal.

[0083] In a second method of providing a hermetic seal, shown in Fig. 24, the spacer 54 is shorter than the spacer aperture 32, whereby both sides 56, 57 of the spacer 54 are recessed from the corresponding block surfaces 38, 40, leaving a first gap 58 between the first side 56 of the spacer and the first surface 38 of the block, and a second gap 59 between the second side 57 of the spacer and the second surface 40 of the block. Alternatively, as in Fig. 26, only one side 57 is recessed from the block surface 40, leaving only one gap 59, and the opposite spacer side 56 extends to the corresponding block surface 38. Alternatively, as in Fig. 27, only the other side 56 is recessed from the block surface 38, leaving only one gap 58, and the opposite spacer side 57 extends to the corresponding block surface 40.

[0084] One or both of the cavities 58, 59 are potted at 60 to seal around the spacer apertures 32 and the signal links 62, thereby creating a hermetic seal. A typical potting material is a two-part epoxy, but any material that provides the desired seal and is minimally affected by the environment can be used. The minimum depth of each cavities 58, 59 that will provide an adequate hermetic seal depends on the environment and the potting material. In one configuration, the depth of the cavities is approximately 0.02 inches, and 0.01 inches or more.

[0085] Most of the figures, although not necessary, show the potting material 60 flush with the block surfaces 38, 40. The potting material 60 may be recessed into the voids 58, 59, as in Figure 27. Because the potting material 60 is initially liquid, it may form a meniscus 68 on its surface.

[0086] The plated tubes 73 are hermetically sealed by filling them with a potting material or by soldering, such as 75 in FIG.

[0087] One method of potting involves applying a reduced pressure to one surface 40 of the block 30, which pulls the potting material 60 from the opposite side, allowing it to be forced into the voids 58 and into all interfaces between the components, such as between the signal links 62 and the spacers 54 or the block 30, between the spacers 54 and the block 30, and between each ground link 71 and the block 30. This reduced pressure ensures that the potting material 60 is forced into all spaces that may provide a leak path between the two environments 1, 2. Of course, this reduced pressure can be applied in the opposite direction from the other surface 38.

[0088] In another method of potting, pressure is applied to the potting material at one surface 38,40, forcing the potting material 60 into any spaces that may provide a leak path between the two environments 1,2.

[0089] The press-fit and potting methods can be utilized simultaneously, for example, in Figure 24, the shorter spacer 54 is sized to be press-fit into aperture 32, the signal link 62 is press-fit into signal aperture 43, and then the gaps 58, 59 are potted.

[0090] The present invention contemplates that the flange 12 is a block 30, i.e., the feedthrough 11 extends through the flange 12 itself, as in FIGS.

[0091] Alternatively, the block 30 is a separate component that is hermetically sealed in the opening 50 of the flange 12. The block 30 can be similar to a connector body, or the block 30 can be a printed circuit board. With the former, there can be more than one block 30 attached to the flange 12, as in FIG. 36. With the latter, more than one PCB can be used, as in FIG. 36, but typically a single PCB is attached in the flange 12, as in FIG. 37. The block 30 is attached in the opening 50 by any suitable means, such as screws or other mechanical means. The seam between the block 30 and the flange 12 can be potted to provide a hermetic seal. Alternatively, a gasket can be used to provide a hermetic seal.

[0092] The connectors 14, 16 removably connect to the feedthrough block 30. A typical connection mechanism is via a jackscrew 290, shown in Figure 38. The jackscrew 290 extends through a hole 292 in the anchor block 88 and passes into a threaded hole 294 in the feedthrough block 30.

[0093] Another embodiment is shown in Figures 39-41. The feedthrough block 30 is an anchor block 88 of the connector 14. The anchor block 88 is attached to the opening 50 in the flange 12 with an O-ring to provide a hermetic seal. Preferably, the connector 14 is removably attached to the flange 12. A jackscrew 212 extends through a hole 214 in the flange 12 and advances into a threaded hole in the anchor block 88.

[0094] The cable holes 91 in the anchor block 88 are also hermetically sealed. If the cables 20 are permanently attached, the attachment means (soldering, crimping, potting with conductive adhesive, insert molding) provides the hermetic seal. If the cables 20 are removably attached to the cable holes 91, the cable holes 91 are potted after the cables 20 are set to hermetically seal them.

[0095] The connectors 14, 16 removably connect to one another using a single plate 89 attached to the removable connector 16. A typical connection mechanism is via a jack screw 290 that extends through a hole 292 in the anchor block 88 of the removable connector 16 and passes into a threaded hole 296 in the anchor block 88 of the connector 14 that is attached to the flange 12, as shown in FIG.

[0096] The present invention contemplates signals much closer together than can be achieved with SMA or SMP, thus greatly increasing the total channel density. Signal spacing can be 0.1 inches or less, more than doubling the channel density over the current state of the art.

[0097] The materials and construction are chosen for mechanical integrity through environmental pressures and cycle life to ensure the lowest possible leak rate, intended controlled impedance, and minimal outgassing. The thickness of the block 30 is determined by the mechanical strength of the block material. In cases where one environment is at a different pressure than the other, the block 30 must be thick enough to remain relatively flat, for example, ±0.01 inches over the area of ​​the surfaces 38, 40 to ensure a proper mating interface. In other cases, the thickness of the block 30 is not critical.

[0098] Thus, a hermetically sealed, controlled impedance feedthrough assembly has been shown and described. All matter set forth in the foregoing specification and shown in the accompanying drawings is intended to be illustrative and not limiting, since certain changes may be made to the disclosure without departing from the scope of the invention.

Claims

1. A controlled impedance feedthrough assembly (10) between a first environment (1) and a second environment (2), comprising: (a) a conductive block (30) having a first surface (38) designed to accommodate said first environment (1) and a second surface (40) designed to accommodate said second environment (2); (b) at least one feedthrough (11) of said block (30) extending between said first surface (38) and said second surface (40); (1) a spacer through aperture (32) extending between a first opening (34) in said first surface (38) and a second opening (36) in said second surface (40); (2) a dielectric spacer (54) within said spacer through aperture (32) having a first surface (56) and a second surface (57); (3) a signal through aperture (43) extending between the first face (56) and the second face (57); and (4) a rigid conductive signal link (62) in said signal through aperture (43) having a first end (65) abutting said first surface (38) and a second end (66) abutting said second surface (40); At least one feedthrough (11) including: Equipped with (c) the feedthrough (11) is hermetically sealed between the first environment (1) and the second environment (2) by a press fit between the dielectric spacer (54) and the spacer through aperture (32) and between the conductive signal link (62) and the signal through aperture (43); A controlled impedance feedthrough assembly (10).

2. The controlled impedance feedthrough assembly (10) of claim 1, wherein said dielectric spacer (54) is comprised of a slightly compressible material.

3. the spacer (54) and the spacer through aperture (32) are shaped to prevent the spacer (54) from being forced through the spacer through aperture (32); 3. The controlled impedance feedthrough assembly (10) of claim 1 or 2, wherein the conductive signal link (62) and signal through aperture (43) are shaped to prevent the conductive signal link (62) from being forced through the signal through aperture (43).

4. 4. The controlled impedance feedthrough assembly (10) of claim 3, wherein the first end (65) of the conductive signal link (62) has a head (63) having a diameter larger than a diameter of the signal through aperture (43).

5. 5. The controlled impedance feedthrough assembly (10) of claim 3 or 4, wherein the spacer through aperture (32) has a stepped diameter (48) creating a shoulder (49) whereby the diameter of the first opening (34) is greater than the diameter of the second opening (36) and the spacer (54) abuts against the shoulder (49).

6. The controlled impedance feedthrough assembly (10) of claim 3, wherein said conductive signal link (62) and said signal through aperture (43) are frustoconical.

7. 7. The controlled impedance feedthrough assembly (10) of any one of claims 1 to 6, further comprising a flange (12) separating the first environment (1) and the second environment (2), the block (30) being mounted within an opening (50) of the flange (12), and a joint between the block (30) and the flange (12) being hermetically sealed.

Images