Feedthrough

Abstract

A feedthrough is provided, the feedthrough comprising a ceramic body; and a plurality of electrical conductors embedded in the ceramic body, wherein the density of the electrical conductors exceeds 1 conductor / 23 mils in a planar cross-section of the ceramic body. 2 (14839μm 2 ).

Description

Technical Field

[0001] The present disclosure relates to a feedthrough comprising an electrical conductor at least partially embedded in a ceramic matrix. The present disclosure also provides a method for making such a feedthrough. Background Art

[0002] Metal-ceramic assemblies are necessary for many applications and are particularly useful in applications where one or more electrical conductors are required to pass through a ceramic insulator to provide one or more conductive connections from one surface of the ceramic insulator to another surface of the ceramic insulator. This arrangement of conductors passing through an insulator is often referred to as a "feedthrough." This arrangement is widely used in, for example, medical, aerospace, transportation, communications, and power tube (e.g., x-ray, radio frequency) applications, and the present disclosure is not limited to any one application.

[0003] While the present disclosure is generally applicable, its utility may be seen with reference to a particularly demanding application, namely providing a solderless hermetic feedthrough for medical applications.

[0004] Electronic biomedical implants are increasingly being used to diagnose, prevent, and treat disease and other conditions. Such implants are typically housed in a hermetic package that includes electrical feedthroughs for signal transmission between the housed electronic device and the environment. Such implantable devices, particularly those that interface with the human nervous system, cochlea, or retina, require multiple leads in very small feedthroughs.

[0005] Biocompatible metal-ceramic feedthrough systems may be considered the most reliable choice for such devices due to their inertness (eg, biocompatibility) and longevity (eg, biostability).

[0006] For certain therapies, it is desirable to increase the number of electrical conductors (which have many names in the field of feedthroughs, including: leads, paths, pins, wires, and vias) in a feedthrough to increase the number of I / O signals. However, it is also desirable to reduce the size of the feedthrough because it is undesirable to implant large devices (including large feedthroughs) into a human or animal body. In particular, it is desirable to reduce the invasiveness of the implantation procedure and / or the nature of the placement of the device for the target therapy requires a small device, such as a retinal implant. When the device design requires both a large number of conductors (i.e., a large number of pins) and a small size of the feedthrough, traditional feedthrough manufacturing techniques are no longer feasible.

[0007] Therefore, there is a need to increase the density of conductors within a feedthrough. However, the prior art limits the spacing of conductors within a feedthrough. Therefore, until now, either the feedthrough (and therefore the device including the feedthrough) must be enlarged, or the number of I / O signals must be reduced, which is undesirable.

[0008] One non-exclusive object of the present disclosure is to provide low-cost miniaturization of biocompatible and biostable co-fired feedthroughs. Another non-exclusive object of the present disclosure is to provide novel three-dimensional architectures. Yet another non-exclusive object of the present disclosure is to provide a low-cost method of manufacturing feedthroughs.

[0009] Conventional gold brazed feedthrough technology is able to provide conductor spacing approaching 0.022 inches (") using 0.004" diameter wire with a gold brazing ring. Additionally, feedthroughs with a large number of leads are constructed using manual techniques to place conductive wires (e.g., pins) with gold brazing rings into pre-formed (e.g., drilled, pressed, stamped) holes in an electrically insulating member (typically a high purity alumina ceramic), which is costly and increases the chance of errors that can result in high scrap rates. In addition to the challenges of manually constructing such feedthroughs, the current practice of using a gold brazing ring to assist in achieving a hermetic bond between the metal pins and the insulator places design limitations. The thickness of the gold brazing ring adds design constraints and limits the proximity in which conductors can be placed adjacent to each other. This limits the density of the conductors, and therefore the extent to which the feedthrough can be miniaturized.

[0010] It has been proposed to manufacture feedthroughs using a tape casting / layer-by-layer stacking process. Here, thin ceramic tapes are first processed to have through holes, which are then filled with metal or ceramic-metal ("cermet") inks. The tapes are then aligned and stacked together and subsequently co-fired to produce feedthroughs, where the aligned filled holes form conductive paths. This technology has size limitations on feature size and shape (in this example, the holes cut in the individual tapes). In addition, since the holes are filled with metal / cermet inks, overflow may occur around the edges of the surface, which tend to protrude from the conductive paths in the sintered state. This reduces the effective distance between the conductive paths to less than the spacing designed to ensure insulation isolation, which may cause electrical failures (e.g., electrical shorts or arcs) in some areas of the device. This overflow may also become a structural defect that, if thermally cycled, will extend, resulting in a loss of hermeticity and possibly delamination. The manufacture of feedthroughs using this technology is also process intensive, thereby increasing costs. In addition, the use of particulate inks (metal / cermet) in this technology may cause problems during I / O termination / connection to other electronic components, especially in high-density or miniature devices. Furthermore, the use of non-metallic fillers within conductive paths increases the resistance of the paths (e.g., reduces conductivity), thereby reducing the electrical efficiency of the device, requiring more energy than would otherwise be required, resulting in the need for a larger battery to achieve a desired device life (thereby limiting device miniaturization), or resulting in a reduced life for a given battery size (thereby limiting the useful life of the device).

[0011] Some known examples of feedthroughs and techniques used to provide feedthroughs for such medical applications include:-

[0012] US8,698,006 (US'006) discloses a feed-through, which includes:

[0013] a. Insulating parts; and

[0014] b. A first conductor and a second conductor electrically isolated from each other by an insulating member.

[0015] Fig.19 1 conductor / 24 mils is disclosed in 2 (i.e., 0.000024 square inches or 15483 μm 2 ) density.

[0016] The method of US'006 includes forming a feedthrough by the following steps:

[0017] a. providing a first insulating member having at least one bonding surface;

[0018] b. Providing a second insulating member;

[0019] c. disposing a conductor between the first insulating member and the second insulating member and along at least a portion of the bonding surface;

[0020] d. bonding the first insulating member and the second insulating member at the bonding surface; and

[0021] e. Exposing a portion of a conductor.

[0022] A problem with the method and feed-through of US'006 is that the pressing force causes the conductor to deform, forming a curved (e.g., zigzag) profile that reduces the conductive efficiency of the conductive path. In addition, without a method of fixing the conductor in place during the pressing operation, the conductor may move, resulting in inaccurate positioning of the conductive path, making subsequent attachment of the conductive path to the device and / or leads complicated. In addition, as the diameter size of the wire increases to above 0.003 inches, it becomes increasingly difficult to make an airtight bond between the insulating component and the conductive wire, which effectively limits the maximum size of the wire that can be used. Finally, the minimum thickness of the thinnest green ceramic plate that can be prepared and placed between the rows of pins limits the minimum spacing between the pins of these rows to 0.016" (0.406mm).

[0023] US7,988,507 (US'507) discloses a feedthrough for an implantable medical device, the feedthrough comprising:

[0024] an electrical insulator comprising a first surface and a second surface; and

[0025] one or more conductive structures configured to extend continuously through the electrical insulator and embedded within the electrical insulator such that each of the one or more conductive structures is circumferentially covered by the electrical insulator, such that opposite ends of the at least one conductive structure are exposed, and such that the at least one conductive structure extends beyond at least the first surface or the second surface,

[0026] The one or more conductive structures include a conductive metal or a metal alloy and have a thickness of a film of the same conductive metal or metal alloy.

[0027] US'507 also discloses a method for forming a conductive feedthrough, the method comprising the following steps:

[0028] (i) forming a conductive structure including sacrificial components and non-sacrificial components;

[0029] (ii) coating at least a portion of the non-sacrificial component with a relatively electrically insulating material; and

[0030] (iii) removing at least a portion of the sacrificial component from the conductive structure,

[0031] Forming the conductive structure including the sacrificial components and the non-sacrificial components includes punching the foil or cutting the foil using electrical discharge machining.

[0032] The coating step (ii) comprises moulding a coating of insulating material on and / or around the conductive structure, and in a preferred embodiment, the insulating material is moulded around desired portions of the conductive structure using powder injection moulding (PIM).

[0033] Problems with the process of US'507 include that in medical applications, noble metals (e.g., platinum) are ideal conductors, and the sacrificial portions of the platinum foil used create waste that requires expensive recycling. In addition, when platinum is stamped from the foil, the individual conductors may become brittle during the stamping process, thereby limiting the diameter of the conductor that can be formed. In addition, the stamping process requires the use of precision stamping dies for each geometry of the feedthrough. In addition, when some portions of the foil are removed from the interior of the foil, the remaining portion within the foil may sag or bend because the removal of material reduces the residual stress of the foil and the removal of mass reduces the stiffness of the remaining portion of the foil. When subjected to the pressure of subsequent molding, this self-sagging or deflection of the remaining material may cause the conductive path to be inaccurately positioned, thereby complicating the subsequent attachment of the conductor to the device and / or lead.

[0034] The methods of US'507 and US'006 restrict the arrangement of conductors to substantially parallel conductor layers. This restriction of conductors to substantially parallel arrangements restricts the conductor paths that can be achieved. This means that additional circuitry external to the feedthrough may be required.

[0035] US2013 / 0032382 (US'382) discloses a hermetic feedthrough for an implantable device, the feedthrough comprising:

[0036] A stack of electrically insulating ceramic alumina sheets, each sheet containing holes, the holes being substantially aligned with each other to form a conductive path through the sheets via the holes filled with a conductive substance; the sheets and the conductive substance having a co-fired bond between the sheets, and the co-fired bond hermetically sealing the holes.

[0037] US'382 also discloses that the resulting tortuous (e.g., staggered, serpentine, zigzag) path of the through-hole improves the hermetic seal of the feed-through by better preventing fluid from leaking along the through-hole. However, this benefit may be offset by the same tortuous path, which increases the impedance to the current flow, thereby reducing the efficiency of the device to which the feed-through is attached compared to a straight through-hole.

[0038] US'382 limits its examples to holes with diameters of 0.006" to 0.008" (152μm to 203μm), through-hole lengths of 0.042" to 0.066" (1067μm to 1676μm), and spacings of ~0.0181" (460μm) that have passed He leak testing. However, only holes with diameters of 0.008" (203μm), lengths of 0.042" (1067μm), and minimum spacings of ~0.028" (711μm) are exemplified as not exhibiting dye penetration.

[0039] Minimum spacing is 18.1 mils (0.0181 in; 460 μm) corresponding to 1 conductor / 328 mils 2 .

[0040] US7,480,988 (US'988), US7,989,080 (US'080), US8,163,397 (US'397) and US5,272,283 (US'283) describe feedthroughs having a metal tube (serving as a conductive path) co-fired to a ceramic insulator, whereby a (hermetic) seal is achieved by compression of the tube as the ceramic shrinks when the assembly is fired and subsequently allowed to cool. While this may be effective when using tubes with diameters exceeding 0.040 inches (1016 μm) and ceramic sheets at least 0.70 inches (17.78 mm) thick, smaller tube diameters cannot be achieved, limiting the minimum possible feedthrough geometry.

[0041] US '283 discloses that it is not possible to prepare a co-fired feedthrough having a large number of conductive paths (cited herein as typically 10-22).

[0042] US'988, US'080 and US'397 also disclose feedthroughs that rely on ceramic insulators composed of 92% or 96% alumina and a high glass content. However, glass is susceptible to hydroxide etching. This etching chemistry can result when the ceramic / glass feedthrough is exposed to an aqueous chloride environment such as that found in the human body. Further exploration of this phenomenon is described in patent US 9,698,662.

[0043] US'988, US'080 and US'397 also describe a method of making a hermetic feedthrough consisting of a ceramic plate less than 0.040" (1.02 mm) thick containing drilled blind holes into which metal wires less than 0.010" (0.256 mm) in diameter are inserted, which are then subsequently co-fired to achieve a hermetic seal, however, no hermetic value is provided. After firing, the ceramic is overlapped on the blind hole side to expose the wire to achieve a conductive path through the insulating ceramic. A helium leak test is performed, although the document does not record whether a dye penetration test is performed. Segmentation (cutting) is then performed to form the periphery of the individual feedthroughs. These documents do not record the closest spacing of the final conductors obtained by this method. These documents also do not mention the insertion method used. It is reasonable to assume that the pin insertion method is manual, requiring manual placement and fixing during the co-sintering operation to keep such small, lightweight, and delicate pins in place. This may also require high labor costs and result in low yields. There are practical limitations on how to place pins close to each other using manual techniques. In addition, grinding the fired ceramic to expose the metal wires (for attachment to electrical connection paths) adds cost. In addition, the examples are limited to parallel wire arrays.

[0044] US8,277,227 (US'227) discloses the manufacture of a feedthrough by inserting conductive pins (wires) into an unsintered (or "green") ceramic and then co-firing (such as described in US'988, US'080 and US'397). The manual assembly of US'227 results in inaccuracies, is time consuming (labor intensive and therefore relatively expensive), and may result in unsatisfactory leakage rates when tested and result in low yields. The methods of US'988, US'080 and US'397 also appear to include such manual assembly. In addition, the final position accuracy of the co-fired pins is insufficient because it relies on manual craftsmanship. This may subsequently cause difficulties when integrating the I / O into the implantable device. This lack of accuracy also inevitably limits the maximum achievable density of the pins in the feedthrough.

[0045] US'227 also discloses that cochlear implants typically rely on feedthroughs containing 22 to 24 conductive pins, and it is desirable to increase the number of pins while reducing the size of the feedthrough. The high degree of labor intensity and specialized techniques (such as back grinding to expose the wires) can cause manufacturing problems. Therefore, US'227 discloses a method for realizing such a co-fired feedthrough, which relies on a thin conductive film to form a conductive path, which does not rely on such a labor-intensive process of placing the wires. However, US'227 provides almost no details of the airtightness values ​​and dye permeability results obtained, the size boundaries of the conductive paths, the spacing boundaries between the paths, the parallelism of the conductive paths, or the positional accuracy.

[0046] US'227 does provide the following relationship: H = f(L, 1 / A, 1 / t), where H represents the airtightness, L is the length of the conductive element measured from the first side to the second side of the insulating portion of the feedthrough, A is the cross-sectional area of ​​the conductive element, and t is the time the interface is exposed to a fluid such as a body fluid. This formula means that a feedthrough with a thick cross-section with a small conductive via diameter (or a cross-section if the cross-section of the conductive path is not circular) improves airtightness compared to a thin feedthrough with a large conductive path diameter.

[0047] US'227 discloses a conductive member thickness of 0.040" to 0.070" (1.02mm to 1.78mm), but does not disclose conductor width, airtightness or dye permeability results, nor does it disclose the thickness of the feedthrough, nor the positional accuracy or closest spacing of the conductive elements. However, US'227 discloses the use of a shaped (e.g., stepped or threaded) conductive member to improve airtightness, so it must be assumed that if the conductive member is not shaped, the airtightness is insufficient. Summary of the invention

[0048] A non-exclusive object of the present specification is to provide improved feedthroughs. These improved feedthroughs can at least partially solve the shortcomings of the prior art (as described above). The improved feedthroughs of the present specification can be provided by the new feedthrough manufacturing methods disclosed herein. These feedthrough manufacturing methods can at least partially solve the shortcomings of the prior art (as described above).

[0049] One (non-exclusive) object of the present specification is to provide a method capable of forming an airtight feedthrough having small spacing between conductors; a method capable of providing an arrangement that does not restrict the conductors to layers; a method capable of being repurposed without the need for precision stamping dies; a method capable of forming non-bent conductive paths; and / or a method capable of providing an array of conductors that are accurately and / or precisely positioned.

[0050] Another (non-exclusive) object of the present specification is to provide a hermetic feedthrough having small spacing between conductors; a feedthrough that does not constrain the conductors into layers; a feedthrough that includes non-bent conductors; and / or a feedthrough that includes an array of conductors that are accurately and / or precisely positioned.

[0051] The feedthroughs may be biocompatible. The feedthroughs may be airtight. In particular, the feedthroughs may be implanted in a human or animal body. Advantageously, the feedthroughs may withstand chemical reactions that may occur in the human body. For example, the feedthroughs may remain airtight during the service life of the implant. For example, 1 to 20 years or longer.

[0052] Another (non-exclusive) object of the present specification is to provide a feed-through having a straight solid metal wire of a range of diameters. Larger diameter wires can improve conduction efficiency.

[0053] Another (non-exclusive) object of the present specification is to provide a method that does not rely on inserting individual wires into the green ceramic, nor on post-grinding the fired ceramic to expose the wires to the feed-through surface (which can be expensive). In other words, it is a (non-exclusive) object to automate the placement of the conductors. Furthermore, it is a (non-exclusive) object to prepare thin profiles and to facilitate the placement of wires close to each other with accurate positioning.

[0054] Another (non-exclusive) object of the present specification is to provide a method that can be implemented by a robot (rather than manually). Such implementation can reduce labor costs and increase the yield of the device. In addition, construction with a robot can be particularly suitable for using thin, closely packed conductors and providing micro feedthroughs.

[0055] Another (non-exclusive) object of the present specification is to eliminate the need to use a gold brazing ring around a conductor. Eliminating the need to use a gold brazing ring can help reduce size constraints. Not using a brazing ring can reduce the spacing required to enable the feedthrough to be miniaturized. In addition, in the prior art, under certain conditions, gold may electromigrate, resulting in a loss of an airtight seal. Bonding the conductor directly to the insulator without the use of gold brazing can eliminate the possibility of electromigration (or reduce the risk of electromigration), which can improve the long-term airtightness of the feedthrough (and therefore improve biostability). In addition, eliminating the need to use a gold brazing ring can reduce the need for costs involved in preparing the feedthrough.

[0056] The method disclosed herein can be used to provide a feedthrough with a large number of pins and / or a miniature feedthrough. In addition, the method disclosed herein can also be used to provide a feedthrough with a small number of pins and / or a non-miniature feedthrough. In addition, the feedthrough construction method of the prior art allows a two-dimensional arrangement of conductors, while the method disclosed herein enables a three-dimensional arrangement of conductors.

[0057] Furthermore, because the methods and feedthroughs of the present specification can use solid metal wire conductors, rather than metal pastes with ceramic additives (or substitutes), conductors with low resistance can be provided within the feedthrough. This in turn can increase device battery life or allow for the use of smaller batteries. Increased battery life can reduce the number of times a medical device must be replaced, thereby reducing the number of surgical procedures required. Furthermore, the lower resistance conductive paths allow the designer of the feedthrough to specify smaller diameter conductors, thereby potentially allowing further miniaturization of the feedthrough, and smaller batteries allow for further miniaturization of implantable devices.

[0058] Further, the methods disclosed herein can provide devices with conductors having non-bent profiles. This can provide low-resistance conductive paths (the ability to maintain a specified small conductive path diameter), prevent or reduce the possibility of forming potential stress steps (which may lead to the loss of hermetic seals), and prevent or reduce the possibility of short-circuit paths between conductors. This is in contrast to prior art methods, in which the wires are deformed during the feedthrough manufacturing process, which may result in curved (e.g., zigzag) conductive paths or processes. Such processes typically rely on pastes or inks that can leak between ceramic layers (e.g., tape layers) of insulating components (thereby providing undesirable short-circuit paths).

[0059] Another potential benefit of the methods and devices disclosed herein is that the conductive paths are accurately positioned compared to prior art manufacturing processes that rely on molding pressure (e.g., compression, injection molding). In the prior art, the conductive paths may move or deflect when molding pressure is applied. As a result, this may change the position of the conductor, making the subsequent attachment of the feedthrough conductor to the device and / or leads complicated. The movement of the path may also reduce the distance between adjacent conductive paths, thereby destroying the resistance of the insulating member. In order to address this movement that occurs using this process, the minimum path design distance between the paths must be increased, thereby hindering the optimal miniaturization of the feedthrough. Therefore, one (non-exclusive) purpose of the present disclosure is to provide a manufacturing method that does not require the application of (significant) molding pressure, which may cause the conductor of the feedthrough to move or deflect.

[0060] Another (non-exclusive) object of the present disclosure is to provide a method that can use (cost-effectively) a range of conductor diameters. As will be apparent, these methods can be used to provide a range of feedthroughs having a range of conductor diameters. Prior art feedthrough manufacturing methods that rely on compaction forces to clamp a conductive wire between green ceramic insulating sheets may have an upper limit to the diameter of the wire that can be successfully pressed. Feedthrough manufacturing methods that rely on inserting small diameter wires into preformed holes in insulating ceramics may have high labor costs and low yields due to the delicate nature of the wires that may bend during insertion. It would be advantageous to provide a method that can use a variety of conductors, as small diameter wires may be required to achieve a certain degree of miniaturization, while devices that need to transmit higher voltage signals may have to use large diameter wires.

[0061] statement

[0062] Therefore, in a first aspect of the present invention, there is provided a feed-through comprising:

[0063] a ceramic body; and

[0064] A plurality of electrical conductors embedded in a ceramic body,

[0065] Where the density of electrical conductors exceeds 1 conductor / 23 mils in a planar cross-sectional area of ​​the ceramic body 2 (14839μm 2 ).

[0066] The density of the electrical conductors is preferably greater than 1 conductor / 22 mils in a planar cross-section of the ceramic body. 2 (14194μm 2 ), or more than 1 conductor / 21 mils 2 (13548μm 2 ), or more than 1 conductor / 20 mils 2 (12903μm 2 ), or more than 1 conductor / 19 mils 2 (12258μm 2 ), or more than 1 conductor / 18 mils 2 (11613μm 2 ), or more than 1 conductor / 17 mils 2 (10968μm 2 ). Preferably, the density of the electrical conductors is no greater than 1 conductor / 9 mils in a planar cross-section of the ceramic body. 2 (5806μm 2 ), or not more than 1 conductor / 12 mils 2 (7742μm 2 ), or not more than 1 conductor / 13 mils 2(8387μm 2 ), or not more than 1 conductor / 14 mils 2 (9032μm 2 ), or not more than 1 conductor / 15 mils 2 , or not more than 1 conductor / 16 mils 2 (10323μm 2 The density of the electrical conductors may be no greater than 1 conductor / 17 mils in the planar cross-section of the ceramic body. 2 Electrical insulation between conductors and / or maintaining adequate hermeticity may be more easily achieved at lower densities.

[0067] Electrical conductor density can generally be increased by reducing conductor diameter. However, larger conductor diameters can help provide mechanical integrity of the feedthrough and meet electrical performance standards (eg, current carrying capacity).

[0068] The present invention also provides a combination of high density and one or more other features, including but not limited to small conductor diameter, multiple conductors in parallel, multiple longitudinal conductors traversing the ceramic body in a non-coplanar relationship, and / or a more uniform volume density.

[0069] When combined with the other features, the density of the conductors preferably exceeds 1 conductor / 300 mils in a planar cross-section of the ceramic body. 2 (193584μm 2 ), or more than 1 conductor / 250 mils 2 (161290μm 2 ), or more than 1 conductor / 200 mils 2 (129032μm 2 ), or more than 1 conductor / 150 mils 2 (96774μm 2 ), or more than 1 conductor / 100 mils 2 (64516μm 2 ), or more than 1 conductor / 50 mils 2 (32258μm 2 ).

[0070] Each of the plurality of electrical conductors may be parallel to each other within 2°. Further, each of the plurality of electrical conductors may be parallel to each other within 1.5°, 1°, 0.5° or 0.2°.

[0071] A feedthrough is also provided that includes a plurality of electrical conductors embedded in a ceramic body, wherein the plurality of elongated electrical conductors traverse the ceramic body in a non-coplanar relationship.

[0072] The plurality of elongate electrical conductors may include at least one planar array of elongate electrical conductors defining a plane, and at least one elongate electrical conductor that is non-parallel to the plane.

[0073] The plurality of elongated electrical conductors may include at least two groups of elongated electrical conductors, the conductors in each group being in a coplanar relationship to define a group plane, and wherein the group planes of at least two of the plurality of groups are non-parallel.

[0074] The plurality of elongated electrical conductors may include at least one set of elongated electrical conductors emanating from a first region of the ceramic body to a second region of the ceramic body, the first region having an area that is smaller than an area of ​​the second region.

[0075] The ceramic body may include one or more walls extending from the base, and at least one of the plurality of elongate electrical conductors may be mounted to traverse the ceramic body from the base to the one or more walls.

[0076] At least two of the plurality of elongate electrical conductors may be mounted non-parallel to traverse the ceramic body emanating from the base toward the one or more walls.

[0077] Each of the plurality of electrical conductors may be substantially straight within the ceramic body along a length of the conductor.

[0078] The plurality of electrical conductors may include a first electrical conductor, a second electrical conductor, a third electrical conductor, a fourth electrical conductor, and / or a fifth electrical conductor.

[0079] In a second aspect of the present invention, there is provided a feed-through, comprising:

[0080] a ceramic body; and

[0081] A plurality of electrical conductors embedded in a ceramic body,

[0082] Where the density of electrical conductors exceeds 1 conductor / 300 mils in a planar cross-sectional area of ​​the ceramic body 2 (193584μm 2 ), and wherein the diameter of the electrical conductor is less than 0.005 inches (127 μm).

[0083] In a third aspect of the present invention, there is provided a feed-through, comprising:

[0084] a monolithic ceramic body; and

[0085] A plurality of electrical conductors embedded in a ceramic body,

[0086] Where the density of electrical conductors exceeds 1 conductor / 300 mils in a planar cross-sectional area of ​​the ceramic body 2 (193584μm 2), and wherein each of the plurality of electrical conductors are parallel to each other within 2°, or each of the plurality of electrical conductors are uniformly spaced within a tolerance of the greater of ±5% or 0.002" (50.8 μm).

[0087] A feed-through is also provided, comprising:

[0088] Ceramic body;

[0089] a first electrical conductor embedded in the ceramic body; and

[0090] a second electrical conductor embedded in the ceramic body,

[0091] Wherein a surface of the first electrical conductor is within 0.0038 inches of a surface of the second electrical conductor.

[0092] A feed-through is also provided, comprising:

[0093] a ceramic body; and

[0094] a first electrical conductor embedded in the ceramic body,

[0095] The electrical conductor has a diameter less than 0.001 inch (25.4 μm).

[0096] A feed-through is also provided, comprising:

[0097] a ceramic body; and

[0098] a first electrical conductor embedded in the ceramic body,

[0099] Among them, the airtightness of the feedthrough is less than 1×10 -10 mbar-l / sec.

[0100] The airtightness of the feedthrough can be less than 1×10 -11 mbar-l / sec.

[0101] A feed-through is also provided, comprising:

[0102] a ceramic body; and

[0103] a first electrical conductor embedded in the ceramic body,

[0104] The ceramic body has a density of at least 95% of the theoretical bulk density with a standard deviation of less than 1.0% (at least 5 sample points taken at intervals of at least 0.002 inches apart).

[0105] Preferably, the density of the ceramic body is at least 96% or at least 97% or at least 98% or at least 98.5% of the theoretical bulk density.Preferably, the standard deviation is less than 0.5% or less than 0.4% or less than 0.3% or less than 0.2%.

[0106] A feed-through is also provided, comprising:

[0107] Ceramic body;

[0108] a first electrical conductor embedded in the ceramic body; and

[0109] a second electrical conductor embedded in the ceramic body,

[0110] The first electrical conductor is parallel to the second electrical conductor within a difference of 2°.

[0111] A feed-through is also provided, comprising:

[0112] Ceramic body;

[0113] a first electrical conductor embedded in the ceramic body;

[0114] a second electrical conductor embedded in the ceramic body; and

[0115] a third electrical conductor embedded in the ceramic body,

[0116] Wherein a distance between a surface of the first electrical conductor and a surface of the second electrical conductor is equal to a distance between a surface of the second electrical conductor and a surface of the third electrical conductor within a tolerance of the greater of ±5% or 0.002" (50.8 μm).

[0117] A feed-through is also provided, comprising:

[0118] Ceramic body;

[0119] a first electrical conductor embedded in the ceramic body;

[0120] a second electrical conductor embedded in the ceramic body; and

[0121] a third electrical conductor embedded in the ceramic body,

[0122] wherein the first electrical conductor and the second electrical conductor are in a first plane;

[0123] wherein the third electrical conductor is not in the first plane; and

[0124] Wherein a surface of the third electrical conductor is within 0.0038 inches of a surface of the first electrical conductor or the second electrical conductor.

[0125] The surface of the first electrical conductor may be within 0.0038 inches (96.5 μm) of the surface of the second electrical conductor within the ceramic matrix along the entire length of the first and second conductors within a tolerance of the greater of ±5% or 0.002" (50.8 μm).

[0126] Tolerance can be measured relative to the maximum distance. Tolerance can be measured relative to the average distance.

[0127] The surface of each of the plurality of electrical conductors may be smooth (e.g., preferably having an average roughness (Ra) value of less than 0.0008 inches (20.3 μm), or more preferably less than 0.0004 inches (10.2 μm), or even more preferably less than 0.0002 inches (5.1 μm), or still more preferably less than 0.000125 inches (3.175 μm)). The surface of the first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor, and / or the fifth electrical conductor may be smooth.

[0128] Each of the plurality of electrical conductors may be straight or linear.The first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may be straight or linear.

[0129] Each of the plurality of electrical conductors may be straight or linear along a portion within the ceramic body.The first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may be straight or linear along a portion within the ceramic body.

[0130] Each of the plurality of electrical conductors may have a substantially constant cross-section.The first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may have a substantially constant cross-section.

[0131] Each of the plurality of electrical conductors may have a solid cross-section.The first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may have a solid cross-section.

[0132] Each of the plurality of electrical conductors may have a substantially constant cross-section along a portion within the ceramic body.The first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may have a substantially constant cross-section along a portion within the ceramic body.

[0133] Each of the plurality of electrical conductors may have a solid cross-section along a portion within the ceramic body.The first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor, and / or the fifth electrical conductor may have a solid cross-section along a portion within the ceramic body.

[0134] Each of the plurality of electrical conductors may have a hollow cross-section.The first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may have a hollow cross-section.

[0135] Each of the plurality of electrical conductors may have a hollow cross-section along a portion within the ceramic body.The first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may have a hollow cross-section along a portion within the ceramic body.

[0136] Each of the plurality of electrical conductors may be parallel to each other within 2°. Each of the plurality of electrical conductors may be parallel to each other within 1.5°. Each of the plurality of electrical conductors may be parallel to each other within 1°. Each of the plurality of electrical conductors may be parallel to each other within 0.5°. Each of the plurality of electrical conductors may be parallel to each other within 0.2°.

[0137] The first electrical conductor may be parallel to the second electrical conductor within 2°. The first electrical conductor may be parallel to the second electrical conductor within 1.5°. The first electrical conductor may be parallel to the second electrical conductor within 1°. The first electrical conductor may be parallel to the second electrical conductor within 0.5°. The first electrical conductor may be parallel to the second electrical conductor within 0.2°.

[0138] The diameter of each of the plurality of electrical conductors may be less than 0.0015 inches, less than 0.001 inches, or less than 0.0005 inches. The diameter of the first electrical conductor may be less than 0.0015 inches, less than 0.001 inches, or less than 0.0005 inches. The diameter of the second electrical conductor may be less than 0.0015 inches, less than 0.001 inches, or less than 0.0005 inches. The diameter of the third electrical conductor may be less than 0.0015 inches, less than 0.001 inches, or less than 0.0005 inches. The diameter of the fourth electrical conductor may be less than 0.0015 inches, less than 0.001 inches, or less than 0.0005 inches. The diameter of the fifth electrical conductor may be less than 0.0015 inches, less than 0.001 inches, or less than 0.0005 inches. The diameter of each of the plurality of conductors is preferably at least 0.00038 inches, more preferably at least 0.0005 inches. Conductors with smaller diameters may be used, although they are not currently commercially available. In theory, assuming low pressure manufacturing techniques are used, the conductor diameter can be as low as at least 0.0001. Conductors with diameters below these diameters may have low stiffness, making them unable to support themselves and therefore more difficult to process in the manufacturing process.

[0139] In another embodiment, the diameter of each of the plurality of electrical conductors may be between 0.020 inches and 0.040 inches (0.508 mm to 1.02 mm). The diameter of the first electrical conductor may be between 0.020 inches and 0.040 inches (0.508 mm to 1.02 mm). The diameter of the second electrical conductor may be between 0.020 inches and 0.040 inches (0.508 mm to 1.02 mm). The diameter of the third electrical conductor may be between 0.020 inches and 0.040 inches (0.508 mm to 1.02 mm). The diameter of the fourth electrical conductor may be between 0.020 inches and 0.040 inches (0.508 mm to 1.02 mm). The diameter of the fifth electrical conductor may be between 0.020 inches and 0.040 inches (0.508 mm to 1.02 mm).

[0140] The minimum distance between the surfaces of adjacent electrical conductors in a planar cross-section of the ceramic body is preferably at least 0.0016 inches (40.6 μm), or at least 0.0019 inches (48.3 μm), or at least 0.002 inches (50.8 μm), or at least 0.003 inches (76.2 μm), or at least 0.004 inches (101.6 μm). Typically, the distance between the surfaces of adjacent electrical conductors does not exceed 0.4 inches (10.16 mm), although greater distances are possible. In some embodiments, the distance between the surfaces of adjacent electrical conductors in a planar cross-section of the ceramic body is less than 0.012 inches (304.8 μm) or less than 0.006 inches (152.4 μm) or less than 0.0038 inches (96.52 μm) or less than 0.0035 inches (88.9 μm).

[0141] The thickness of the feedthrough may be less than 0.063 inches (1600.2 μm), less than 0.050 inches (1270.0 μm), less than 0.040 inches (1016.0 μm), or less than 0.030 inches (762.0 μm).

[0142] The ceramic body may have a first surface. The ceramic body may have a second surface. The first surface and the second surface of the ceramic body may be parallel.

[0143] The thickness of the feedthrough between the first surface of the ceramic body and the second surface of the ceramic body may be less than 0.063 inches (1600.2 μm), less than 0.050 inches (1270.0 μm), less than 0.040 inches (1016.0 μm), or less than 0.030 inches (762.0 μm).

[0144] The cross-section of the plurality of electrical conductors may have a substantially constant cross-section such that the cross-sectional area of ​​the conductor varies by less than 10%. Preferably, the cross-sectional area varies by less than 5%, more preferably less than 3%.

[0145] Each of the plurality of electrical conductors may extend from the first surface of the ceramic body to the second surface of the ceramic body. The first electrical conductor may extend from the first surface of the ceramic body to the second surface of the ceramic body. The second electrical conductor may extend from the first surface of the ceramic body to the second surface of the ceramic body. The third electrical conductor may extend from the first surface of the ceramic body to the second surface of the ceramic body. The fourth electrical conductor may extend from the first surface of the ceramic body to the second surface of the ceramic body. The fifth electrical conductor may extend from the first surface of the ceramic body to the second surface of the ceramic body.

[0146] Each of the multiple electrical conductors and / or the first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may have a resistivity between the first surface of the ceramic body and the second surface of the ceramic body at room temperature that is less than 4E-05 (Ω.cm) for Pt / Ir (90 / 10).

[0147] Preferably, the resistivity of each of the multiple electrical conductors and / or the first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor between the first surface of the green ceramic body (i.e. before sintering) and the second surface of the green ceramic body at room temperature may be less than 70% or less than 60%, more preferably less than 50% or less than 40%, even more preferably less than 30% or less than 25%, even more preferably less than 20%, compared to the electrical conductor embedded in the ceramic body (i.e. after sintering).

[0148] The density of the ceramic body is preferably at least 95%, more preferably at least 96% or at least 97%, even more preferably at least 98% or at least 98.5%, even more preferably at least 99% of the theoretical bulk density. The standard deviation of the density (minimum 5 samples, preferably minimum 7 samples) is preferably less than 1.0%, more preferably less than 0.5%, even more preferably less than 0.2%.

[0149] The individual electrical conductors in the plurality of electrical conductors may be separated from each other. The first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may be separated from each other.

[0150] Individual electrical conductors in the plurality of electrical conductors may be electrically isolated from one another.The first electrical conductor, the second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may be electrically isolated from one another.

[0151] The distance between the surface of each of the plurality of electrical conductors and the surface of another electrical conductor may be equal within a tolerance of the greater of ±5% (preferably ±4%, more preferably ±3%) or 0.002" (50.8 μm). The tolerance may be measured relative to a maximum distance. The tolerance may be measured relative to an average distance.

[0152] The plurality of electrical conductors may include at least three conductors, at least four conductors, at least five conductors, at least six conductors, at least seven conductors, at least eight conductors, at least nine conductors, at least ten conductors, at least 11 conductors, at least 12 conductors, at least 13 conductors, at least 14 conductors, at least 15 conductors, at least 16 conductors, at least 17 conductors, at least 18 conductors, at least 19 conductors, at least 20 conductors, at least 24 conductors, at least 25 conductors, at least 30 conductors, at least 35 conductors, at least 40 conductors, at least 45 conductors, at least 48 conductors, at least 50 conductors, at least 55 conductors, at least 60 conductors, at least 65 conductors, at least 70 conductors, at least 72 conductors, at least 73 conductors, at least 74 conductors, at least 75 conductors, at least 76 conductors, at least 77 conductors, at least 78 conductors, at least 79 conductors, at least 80 conductors, at least 81 conductors, at least 82 conductors, at least 83 conductors, at least 84 conductors, at least 85 conductors, at least 86 conductors, at least 87 conductors, at least 88 conductors, at least 89 conductors or more. The present invention relates to a method of manufacturing a plurality of conductors of the present invention. The method comprises: manufacturing a plurality of conductors of the present invention. The plurality of conductors of the present invention comprises: a plurality of conductors of the present invention, at least 75 conductors, at least 80 conductors, at least 85 conductors, at least 90 conductors, at least 95 conductors, at least 92 conductors, at least 100 conductors, at least 120 conductors, at least 144 conductors, at least 168 conductors, at least 192 conductors, at least 216 conductors, at least 240 conductors, at least 264 conductors, at least 288 conductors, at least 312 conductors, at least 336 conductors, or at least 360 conductors, or at least 720 conductors, at least 780 conductors, at least 840 conductors, at least 900 conductors, at least 960 conductors, at least 1020 conductors, at least 1080 conductors, at least 1440 conductors and at least 1800 conductors and at least 2160 conductors.

[0153] Properties of the first conductor, the second conductor, the third conductor, the fourth conductor and / or the fifth conductor and the relationship between the first conductor, the second conductor, the third conductor, the fourth conductor and / or the fifth conductor may also be characteristics of some or all of the plurality of conductors (e.g., three of the plurality of conductors, four of the plurality of conductors, five of the plurality of conductors).

[0154] The second electrical conductor, the third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may have any or all of the properties and / or relationships with the first electrical conductor described above.

[0155] The third electrical conductor, the fourth electrical conductor and / or the fifth electrical conductor may have any or all of the properties and / or relationships with the first electrical conductor and / or the second electrical conductor described above.

[0156] The feed-through may include additional electrical conductors. The additional electrical conductors may have any or all of the properties and / or relationships with the other electrical conductors described above.

[0157] The feedthrough may include a second, third, fourth and / or fifth plurality of electrical conductors.The second, third, fourth and / or fifth plurality of electrical conductors may have any of the features described above with respect to the plurality of conductors.

[0158] The feedthrough may be implantable in a human or animal body. The feedthrough may be biocompatible. Biocompatible materials are compatible with living tissue. Biocompatible materials do not produce toxic or immunological reactions when exposed to the body or body fluids.

[0159] The feed-through may also include a flange or a ferrule.

[0160] The flange or ferrule may be or include titanium, niobium, tantalum, diamond, stainless steel, aluminum, copper, nickel, tungsten, platinum, or alloys thereof.

[0161] The flange or ferrule may be hermetically bonded to the ceramic.

[0162] The feedthrough may be bonded to a titanium alloy flange or ferrule by using a brazing alloy that does not contain gold so that the transformation temperature of the titanium alloy is not exceeded.

[0163] The feed-through described above may advantageously be included in the device.

[0164] Therefore, a device, such as a medical device, comprising the above feed-through is also provided.

[0165] The housing of the medical device may be bonded to the ceramic of the feedthrough.

[0166] The housing of the medical device may be bonded to the flange or ferrule (when present) of the feed-through.

[0167] The housing may be or include titanium or a titanium alloy.

[0168] The feedthrough may be hermetically bonded to the medical device.

[0169] The feedthrough may be bonded to the titanium alloy housing of the medical device by using a brazing alloy that does not contain gold so that the transformation temperature of the titanium alloy is not exceeded.

[0170] A green body for co-firing to form the feedthrough described above is also provided.

[0171] Thus, there is also provided a green body for co-firing to form a feed-through, the feed-through comprising:

[0172] green ceramic bodies; and

[0173] A plurality of electrical conductors embedded in a ceramic body,

[0174] Where the density of electrical conductors exceeds 1 conductor / 23 mils in a planar cross-section of the green ceramic body 2 (14839μm2 ).

[0175] Also provided is a green body for co-firing to form a feedthrough comprising a plurality of electrical conductors embedded in a green ceramic body, wherein the plurality of elongated electrical conductors traverse the green ceramic body in a non-coplanar relationship.

[0176] Methods for forming the feedthroughs and green bodies are also provided.

[0177] Thus, there is provided a method for forming an assembly of electrical conductors, the electrical conductors being at least partially embedded in a ceramic or ceramic precursor matrix, the method comprising the steps of:

[0178] a) mounting a plurality of elongated electrical conductors to a frame to form a conductor-frame assembly comprising a plurality of elongated electrical conductors;

[0179] b) introducing a fluid ceramic or ceramic precursor into the cavity to form a self-supporting body,

[0180] Therein, at least a portion of the elongated electrical conductor is embedded in the self-supporting body.

[0181] Mounting the plurality of elongate electrical conductors to the frame preferably includes fixedly attaching the plurality of elongate electrical conductors to the frame.

[0182] The method enables the preparation of monolithic ceramic structures in which the embedded electrical conductors are not subjected to forces that could significantly deform the conductors from their original frame positions. This is in contrast to layered ceramic structures in which the electrical conductors are subjected to excessive pressures (e.g., greater than 2 atmospheres (absolute)) during their formation, resulting in deformation of the electrical conductors. Thus, the method enables the manufacture of ceramic structures that combine small conductor diameters, small minimum distances between surfaces of adjacent electrical conductors, small center-to-center spacing between conductors, and high conductor density.

[0183] There is also provided a use of a fluid ceramic or a fluid ceramic precursor in the manufacture of a feedthrough, wherein the fluid ceramic or fluid ceramic precursor is introduced into a cavity at a pressure of less than 2 atmospheres (absolute) to form a self-supporting ceramic body. The conductor-frame assembly preferably traverses the cavity before the fluid ceramic or ceramic precursor is introduced.

[0184] In some embodiments, the conductor-frame assembly is positioned into the self-supporting body (i.e., after the fluid ceramic or ceramic precursor is introduced into the cavity). In this embodiment, the elongated electrical conductor is preferably mounted to the frame at one end so that the frame is not embedded in the self-supporting body. A low viscosity (e.g., within 1 second) is preferred. -1The solid loading of the ceramic fluid or ceramic precursor may be in the range of 10 to 80 volume %, depending on the solid properties. More preferably, the solid loading is in the range of 20 to 60 volume %.

[0185] In order to minimize the tolerance of the spacing between the conductors, preferably each end of the elongated electrical conductor is mounted to the frame. Preferably, the elongated electrical conductor has no intermediate supports between the respective ends of the elongated electrical conductor. However, in some embodiments where the elongated electrical conductor is not rigid enough to be self-supporting, an intermediate support may be used. The intermediate support is preferably green ceramic and more preferably has the same composition as the self-supporting body.

[0186] The term "elongated electrical conductor" includes, but is not limited to, wires, ribbons, pins, rods, tubes and bars made of conductive material.

[0187] "Transverse to the cavity" means extending across or through at least a portion of the cavity, and should not be construed as limited to extending across the entire extent of the cavity. "Transverse" should be construed in a similar manner.

[0188] "Fluid ceramic or ceramic precursor" should be understood to mean a fluid comprising a ceramic or ceramic precursor. "Ceramic precursor" means a material that, while not necessarily a ceramic itself, can be converted into a ceramic by appropriate processing. Fluid means capable of flowing under applicable processing conditions and includes, but is not limited to, fine particles, slurries, slips, suspensions, solutions, pastes, and mixtures thereof.

[0189] By "self-supporting body" is meant a body that does not collapse when the frame is removed.

[0190] The cavity may have a perimeter defined at least in part by the frame.

[0191] The method may also include removing at least a portion of the frame.

[0192] A plurality of elongate electrical conductors may traverse the cavity in a coplanar relationship, lying in a single plane.

[0193] A plurality of elongated electrical conductors may traverse the cavity in a non-coplanar relationship.

[0194] The plurality of elongate electrical conductors may include at least one planar array of elongate electrical conductors defining a plane and at least one elongate electrical conductor that is non-parallel to the plane.

[0195] The plurality of elongate electrical conductors may traverse the cavity in at least two groups of elongate electrical conductors, the conductors in each group being in a coplanar relationship to define a group plane.

[0196] Group planes of at least two groups among the plurality of groups may be non-parallel.

[0197] The plurality of elongated electrical conductors may include at least one set of elongated electrical conductors radiating from a first region of the cavity periphery to a second region of the cavity periphery, the first region having an area smaller than an area of ​​the second region.

[0198] The cavity may include one or more walls extending from the base, and at least one of the plurality of elongate electrical conductors may be mounted to traverse the cavity from the base to the one or more walls.

[0199] At least two of the plurality of elongate electrical conductors may be mounted non-parallel to traverse the cavity from the base to the one or more walls.

[0200] The frame may comprise a plurality of frame sections that are assembled to form the frame.

[0201] The method may further comprise the following steps:

[0202] d) mounting each of the first set of elongated electrical conductors by its ends to the first set of frame portions;

[0203] e) securing the second set of frame portions to the first set of frame portions in a fixed relationship;

[0204] f) mounting each of the second set of elongate electrical conductors by one end to the second set of frame portions and by another end to either the first set of frame portions or the second set of frame portions.

[0205] Steps d), e) and f) may be repeated to successively mount subsequent groups of frame parts to each group of frame parts, and each conductor in each group of longitudinal electrical conductors is mounted to the frame part of the subsequent group via one end and to the frame part of the subsequent group or the frame part of the previously mounted group via the other end.

[0206] One or more groups of frame portions may be or comprise a single frame portion.

[0207] One or more elongated electrical conductors may be mounted by one end to the frame portion and by another end to an electronic component disposed in the cavity to be embedded in the ceramic.

[0208] The elongated electrical conductors are preferably fixedly attached to the frame.Any suitable attachment means may be used, including but not limited to diffusion bonding, mechanical fastening, adhesives (eg, UV curable resins), laser assisted diffusion bonding, and welding (eg, laser welding, hard welding, and / or soft welding).

[0209] Mounting the plurality of elongate electrical conductors to the frame preferably includes welding to join the elongate electrical conductors to a metal region of the frame.

[0210] The frame is preferably more rigid than the elongate electrical conductor it supports.The frame is preferably sufficiently rigid that the frame retains its shape during the introduction of the fluid ceramic or precursor thereof to be embedded in the conductor.

[0211] The frame may be metallic, and the metallic region of the frame may comprise a surface portion of the frame.

[0212] The frame may be non-conductive and the metallic areas of the frame may include metal inserts in the frame.

[0213] The longitudinal electrical conductor may include nickel, molybdenum, tantalum, tungsten or their alloys. Additionally or alternatively, the longitudinal electrical conductor includes Pt, Ir, Nb, Pd, Au, Os, Ni, Cr, W, Mo, Ta, Fe, Co, Ti, Rh, Re, Zr, V and their alloys, which may also be used for the conductor.

[0214] The elongated electrical conductor may include a platinum group metal or alloy. In an embodiment, for narrow diameter conductors (e.g., <0.002 inches (50.8 μm)), a platinum alloy (e.g., 5wt% Ir / 95wt% Pt) or a conductor having a stiffness equal to or greater than 5wt% Ir / 95wt% Pt is preferred to increase positional stability during manufacturing. A more rigid conductor also enables longer lengths of feedthrough to be fixedly attached to the frame during manufacturing.

[0215] The metal region of the frame may include an iron alloy. For example, an iron-nickel alloy. The iron-nickel alloy may include 30wt% to 40wt% nickel and / or 60wt% to 70wt% iron, for example, 36% Ni+Fe. Additionally or alternatively, Fe, Ni, Pd, Pt, Co, Cr, Al, Cu, Mo, Ta, W, and alloys thereof may also be used.

[0216] The body may be formed in the cavity as a green ceramic body that is fired to co-sinter the ceramic to the elongate electrical conductor to provide a gas-tight bond between the ceramic and the elongate electrical conductor.

[0217] There is also provided a feed-through comprising a plurality of elongated electrical conductors embedded in a ceramic body and obtainable by the above method.

[0218] A feed-through is also provided, comprising a plurality of elongated electrical conductors embedded in a ceramic body and obtained by the above method.

[0219] Features described with respect to an assembly or a method for a feedthrough or an electrical conductor may be features of the assembly or the method for a feedthrough or an electrical conductor even if they are explicitly listed mutatis mutandis.

[0220] The terms "inch" and "" are used interchangeably throughout this specification.

[0221] The term "diameter" includes the effective diameter (the average of the width at the largest diameter and the narrowest diameter).

[0222] The term "milliinch" is equal to 0.001 inch. 2 Equal to 0.000001 inches 2 or square inches.

[0223] Other aspects of the disclosure will be apparent from the claims and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0224] Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0225] Figure 1 schematically illustrates a plurality of elongated electrical conductors mounted to a lead frame;

[0226] Figure 2 A picture showing platinum wire bonded to a Fe-Ni lead frame;

[0227] Figure 3 (a), (b), (c) show SEM micrographs of the platinum-Fe-Ni invar alloy joint at 170x, 1200x and 12000x magnifications, respectively;

[0228] Figure 4 Schematically shows a plurality of stacked prior to forming a ceramic body to be embedded in at least a portion of an elongated electrical conductor Figure 1 Lead frame;

[0229] Figure 5 A generalized flow chart showing steps in a method of forming an assembly of an electrical conductor at least partially embedded in a ceramic matrix is ​​shown;

[0230] Figure 6 (a) and (b) respectively show a plurality of frame portions having elongated electrical conductors mounted thereon prior to forming a ceramic body to be embedded with at least a portion of the elongated electrical conductors and the resulting pattern of conductors embedded in a ceramic (not shown);

[0231] Figure 6(c) and (d) show, respectively, a cross-sectional view of a plurality of frame portions having mounted thereon at least a portion of the elongated electrical conductors prior to forming a ceramic body to be embedded therein and a cross-sectional view of the resulting pattern of conductors embedded in a ceramic (not shown);

[0232] Figure 7 (a), (b) and (c) respectively show a top view, a bottom view and a cross-sectional view of the feed-through;

[0233] Figure 8 (a) and (b) respectively show a further flange Figure 7 A top view and a cross-sectional view of a feed-through;

[0234] Fig. 9 (a) and (b) schematically illustrate another feedthrough;

[0235] Fig. 9 (c) schematically shows another feedthrough incorporated into the device;

[0236] Fig.10 schematically illustrates the fabrication of a feedthrough prepared in accordance with the present disclosure;

[0237] Fig.11 is a micrograph of a cut cross section of a feedthrough;

[0238] Fig.12 shows a polished cross section of a platinum pin embedded in alumina;

[0239] Fig.13 A method for assembling a conductor-frame assembly prior to further processing is schematically illustrated;

[0240] Fig.14 Schematically shows the installation relative to Figure 1 a plurality of elongated electrical conductors of an alternative lead frame to the lead frame shown;

[0241] Fig.15 Schematically showing the arrangement of conductors extending from a tight mounting area to a wide mounting area;

[0242] Figures 16(a), (b) and (c) show SEM micrographs of cut cross sections of prior art feedthroughs;

[0243] Fig.17 (a), (b) and (c) show SEM micrographs of cut cross sections of the feedthrough;

[0244] Fig.18 An X-ray image of the feedthrough is shown;

[0245] Fig.19An alternative X-ray image of the feedthrough is shown;

[0246] Fig. 20 shows an SEM micrograph of a cut cross section of a feedthrough;

[0247] Fig.21 Shows Fig. 20 Magnified view of the SEM micrograph;

[0248] Fig. 22 shows an SEM micrograph of a cut cross section of a feedthrough;

[0249] FIG23 schematically illustrates the density of a feedthrough constructed according to a prior art method;

[0250] Fig.24 The density of the feedthroughs is schematically shown;

[0251] Fig.25 shows the mathematical method used to calculate conductor density; and

[0252] Fig.26 A SEM micrograph of a cut cross section of another feedthrough is shown. DETAILED DESCRIPTION

[0253] Overall description of the process

[0254] The present disclosure provides a method of forming an assembly of an electrical conductor at least partially embedded in a ceramic or ceramic precursor matrix, the method comprising the steps of:

[0255] a) mounting a plurality of elongated electrical conductors to a frame to form a conductor-frame assembly, the conductor-frame assembly comprising a plurality of elongated electrical conductors traversing the cavity;

[0256] b) introducing a fluid ceramic or ceramic precursor into the cavity to form a self-supporting body embedding at least a portion of the elongated electrical conductor.

[0257] Figure 1 Schematically shown are a plurality of elongated electrical conductors 1 mounted to a lead frame 2 to form a conductor-frame assembly 3. The elongated electrical conductors 1 extend within a cavity 4 defined by a wall 5 of the lead frame 2. The elongated electrical conductors 1 may be mounted or fixedly attached to the lead frame by any convenient means, for example adhesively, by soldering, welding or otherwise.

[0258] Figure 2 shows a picture of platinum wire bonded to a Fe-Ni lead frame, and Figure 3 Details of such a bond are shown in (a), (b) and (c). Details of why such a combination may be advantageous are given below under the heading "Conductor and frame".

[0259] For a feedthrough comprising a single layer of conductors, the conductor-frame assembly may be mounted in a die and ceramic formed around the elongated electrical conductor 1 in cavity 4. The fluid ceramic or ceramic precursor may be introduced through holes in the die, or through optional holes 6 formed in the leadframe 2, or both.

[0260] For feedthroughs comprising two or more layers of conductors, the conductor-frame assemblies 3 may be stacked.

[0261] Figure 4 A plurality of conductor-frame assemblies 3 are shown stacked adjacent to form a conductor frame such that the elongated electrical conductors 1 form a multilayer array of elongated electrical conductors 1. Subsequent formation of a ceramic body with at least a portion of the elongated electrical conductors 1 embedded forms an assembled ceramic body with embedded parallel elongated electrical conductors 1. The assembled ceramic body can be processed while in a frame (which is subsequently removed) and / or after the frame is removed.

[0262] For example, the ceramic body can be a green ceramic body that is subsequently fired to sinter and densify the ceramic, as described below.

[0263] As shown, the individual conductor-frame assemblies 3 are shown stacked in a parallel relationship. This is not essential, particularly if it is desired that the conductors radiate from a first region on one face of the ceramic body to a second region of the ceramic body, the first region being smaller in area than the second region.

[0264] Depending on the nature of the ceramic used, processing of the assembled ceramic body may include (but is not limited to) the steps of drying, curing, sintering, annealing or melting or a combination of two or more of these steps. Details of specific ceramics are given below under the heading "Ceramics".

[0265] Processing of the assembled ceramic body may also include (but is not limited to) slicing the assembled ceramic body to form feedthroughs, polishing, external grinding (e.g., OD grinding, profile grinding), slicing, polishing (if necessary), metallizing the surfaces to be brazed, brazing, testing (e.g., air tightness testing). Of course, other subsequent processing steps known to those skilled in the art may also be used.

[0266] One particularly useful process is to co-sinter the green ceramic body to form a monolithic dense ceramic body around the conductor. It has been demonstrated that co-sintering of metals, such as platinum (e.g., platinum group metals [Pt, Ir, Os, Pd, Rh, Ru] or alloys thereof), with oxide / non-oxide ceramics occurs without any surface degradation of the metal phase if an appropriate (e.g., non-oxidizing) atmosphere is used during sintering to inhibit metal degradation.

[0267] Studies have shown that certain refractory metals (e.g., platinum, molybdenum, nickel, tungsten, and their alloys) do not react significantly (e.g., oxidize, nitride) when co-sintered with oxide and / or non-oxide ceramics. Such reactions can inhibit the properties of the feedthrough (e.g., conductivity and airtightness), making these metals particularly suitable for use in feedthroughs. In addition, the sintering stress from the ceramic matrix during the densification process causes the polycrystalline matrix to shrink and press against the plastic surface of the platinum or other refractory metal at the ceramic sintering temperature (1050°C to 1800°C). This mechanical stress ensures a strong mechanical bond between the metal and the ceramic matrix. When the composite is sintered to full density, it ensures that the bond between the metal / alloy conductor and the ceramic matrix is ​​airtight. "Full density" refers to a density greater than 90% of the theoretical density, greater than 94% of the theoretical density, greater than 98% of the theoretical density, or greater than 99% of the theoretical density.

[0268] The present disclosure is not limited to co-sintering, but the technique is particularly useful.

[0269] Figures 1 to 4 The process illustrated in can produce a feedthrough in which the conductors are generally arranged in layers, although the spacing between conductors is small compared to the prior art [see Example 1 below]. The overall process conforms to Figure 5 A flow chart is shown which gives an overview of the process.

[0270] Figure 6 and Figure 7 A method is shown which allows for more complex conductor geometries to be achieved, wherein the lengthwise electrical conductors are in a non-layered relationship.

[0271] exist Figure 6 In (a) and 6(c), the elongated electrical conductor 1 is bonded to the substrate / ring at one end in a predefined pattern and to the subsequently stacked lead frame portion / ring at the other end. The conductor is subsequently encapsulated in a self-supporting ceramic or ceramic precursor body, producing Figure 6 (b) and Figure 6 3D conductor structure shown in (d) of FIG. 1 , in which the longitudinal electrical conductor 1 diverges from the base plane 7 to multiple positions shifted from the base plane 7 .

[0272] Figure 6 (c) shows the ratio Figure 6 (a) Typical process in more detail.

[0273] In this process, the first conductors 7 are each mounted to the substrate 8 by one end, and mounted to the first frame layer 9 by their other ends.

[0274] Then, the second frame layer 10 is stacked over the first frame layer 9 , and the second conductor 11 is mounted to both the substrate 8 and the second frame layer 10 in a similar manner.

[0275] The second conductor 11 may be mounted to the substrate 8, radially and / or rotationally displaced relative to the first conductor 7 to provide the desired spacing, or may be mounted in line with the first conductor 7, wherein the intention is to provide a common connection for the first conductor 7 and the second conductor 11. The process is repeated by stacking frame layers in sequence until the desired height is reached.

[0276] The frame layers can be stacked directly on each other or with spacers placed between the frame layers. Further details of the frame layers can be found under "Conductors and Frames" below. As will be apparent to those skilled in the art, the frames can be stacked in a horizontal or vertical manner, depending on the design of the desired feedthrough.

[0277] After forming a self-supporting ceramic or ceramic precursor body, the frame portion is removed to leave a ceramic body 12 ( Figure 6 (d)). Depending on the material used, the frame portion can be removed mechanically (e.g., by grinding away) or chemically (e.g., by dissolving) or both. Depending on how it is mounted to the frame, the elongated conductors may leave protruding portions 13, which may be useful in some applications.

[0278] exist Figure 7 , a feedthrough 14 is shown comprising a first face 14 and an opposite second face 15. The elongated electrical conductors 1 diverge to form a non-collinear and non-coplanar 3D array. The elongated electrical conductors 1 diverge from a narrowly spaced 2D array 17 on the second face 15 to a widely spaced 2D array 18 on the first face 16, where they terminate at contacts 19.

[0279] exist Figure 8 In (a) and (b), Figure 7 The feedthrough 14 is shown mounted in a flange or ferrule 51. The feedthrough 14 is shown mounted to the flange or ferrule 51 by a brazed joint 52. However, any alternative joint may be used. For example, the feedthrough may be attached to the device using techniques described in US 8,103,433 and / or US 9,351,436, which are incorporated herein by reference.

[0280] Figure 8 (c) schematically shows a feedthrough 14 included in the device 53. As shown, no flange or ferrule is used to attach the feedthrough 14 to the device 53. However, depending on the design of the device 53, a flange or ferrule may be used.

[0281] Fig. 9(a) and (b) show a feedthrough 20 including two groups of elongated electrical conductors, the conductors in the first conductor group 21 define a first group of planes in a coplanar relationship, and the conductors in the second conductor group 22 define a second group of planes in a coplanar relationship. The conductors in the first conductor group 21 are in a parallel relationship to each other. The conductors in the second conductor group 22 are also in a parallel relationship to each other. However, the conductors can diverge within their respective group planes.

[0282] The first set of planes 21 includes 24 conductors. There are 14 other sets of planes parallel to the first set of planes 21. The second set of planes 22 includes 10 conductors. There are 5 other sets of planes parallel to the second set of planes.

[0283] It should be noted that the examples shown above are by no means the only geometries that can be produced. Many complex shapes can be envisioned that can be produced by the technique of mounting the conductors to a frame and embedding the conductors in the ceramic before removing the frame. These shapes include geometries like hemispherical curved contacts and hollow 3D shapes, among others.

[0284] Furthermore, individual ceramic bodies including embedded conductors may themselves be joined to form more complex arrangements.

[0285] Fig.13 A process for preparing a conductor-frame assembly is schematically shown. The process includes:

[0286] a) mounting each of the first set of elongate electrical conductors by its ends to the first set of frame portions;

[0287] b) mounting the second set of frame sections to the first set of frame sections;

[0288] c) mounting each of the second set of elongate electrical conductors by one end to the second set of frame portions and by another end to either the first set of frame portions or the second set of frame portions.

[0289] If the plurality of groups of frame parts with elongated electrical conductors provide the desired architecture, the group of frame parts is passed on for further processing. Otherwise, the process is repeated, with the product of one cycle forming the first group of frames for the next cycle. During this process, electronic components can optionally be mounted to the frames for embedding in the ceramic.

[0290] Wire and frame

[0291] Depending on the application, the elongated electrical conductors may be made of any suitable material, but particularly useful materials for use when a co-sintered ceramic is desired are inert or refractory metals such as platinum, niobium, iridium, nickel, etc., or alloys thereof as a combination thereof. In the following examples, platinum and 10% Ir / Pt are used. Thus, Pt or 0-15% Ir / Pt or 0-10% Ir / Pt or 8-12% Ir / Pt may be used to form the conductor. Pt, Ir, Nb, Pd, Au, Ni, Cr, W, Mo, Ta, Fe, Co, Ti, Rh, Re, Zr, V and alloys thereof may also be used for the conductor.

[0292] Furthermore, if non-precious metals are used, the frame can be produced economically.

[0293] A wide variety of metals and alloys can form solid solutions with platinum.

[0294] For this reason, alloys Fe-X (X = Ni, Pd and Pt) of the Invar family have been considered as candidates for lead frame materials. Fe-Ni alloys were chosen for the following examples, especially 36% Ni+Fe, because they are cheaper than the other two in the Invar family. However, Fe, Ni, Pd, Pt, Co, Cr, Al, Cu, Mo, Ta, W and their alloys may also be used.

[0295] Figure 2 Pt wires welded to the Fe-Ni framework are shown. Figure 3 (a), (b) and (c) show scanning electron micrographs of the Pt-Invar interface at 170X, 1200X and 12000X magnifications, respectively, demonstrating good bonding.

[0296] The conductor and frame sizes are selected to meet the application. Typical conductor diameters are 0.00038 inches or 0.001 inches to 0.040 inches. For example, 0.0005 inches, 0.001 inches, 0.002 inches, 0.005 inches, 0.010 inches, 0.020 inches, 0.030 inches, or 0.040 inches. Typical conductor ranges include any of these values, for example, 0.0005 inches to 0.005 inches, 0.0005 inches to 0.002 inches, 0.0005 inches to 0.001 inches, 0.001 inches to 0.002 inches.

[0297] The frame portion to which the elongate conductor is mounted and the spacer between the adjacent frame portions may include a recess to accommodate the portion of the conductor located between the adjacent frame portions.

[0298] The frame and frame portions may each comprise a single body of material to which the conductors are bonded, or a composite body comprising regions of material to which the conductors may be bonded and regions of material to which the conductors may not be bonded. Fig.14 Shown with Figure 1 A conductor-frame assembly is similar to the conductor-frame assembly 3, but wherein the non-conductive lead frame 33 carries a metal pad 34, which can be surface mounted or embedded in the non-conductive lead frame 33, and wherein the longitudinal conductor is mounted to the metal pad 34.

[0299] It should be noted that it can sometimes be difficult to precisely mount the wires to the frame where very narrow conductor spacing is required. In some cases, this can be addressed by positioning the conductors closer to the frame than the desired conductor spacing, then machining to expose the conductors at the desired conductor spacing. Fig.15 The conductors 1 are shown mounted to the frame in a tight mounting area 35, further separated in a wide mounting area 36, ​​and then after the ceramic body is formed, the surface of the ceramic body is removed to expose the plane 37 of the desired conductor spacing.

[0300] It will be appreciated that after the method is completed, part or all of the framework may be reused.

[0301] Solid conductors with circular cross-sections may be used. In particular, since such conductors can be used as wires, they may be economical. Avoiding angled geometries (e.g., ovals) also mitigates the risk of crack formation during the co-sintering process. However, other cross-sectional shapes may be used. For example, a hollow conductor may be used in the method to provide a feed-through having a hollow conductor.

[0302] ceramics

[0303] Depending on the application requirements, any oxide, non-oxide, or oxide-non-oxide mixture may be used. Typical ceramics and composites include, but are not limited to, BN, B 4 C.Si 3 N 4 、TiC、TiN、TaN、Al 2 O 3 、ZrO2、SiO 2 , MgO, ZnO, CaO, BeO, MnO, Y 2 O 3 , Nb 2 O 5 Cr 2 O 3 SnO 2 、MnO 2, TaO, CuZO, BeO, NiO and other lanthanide oxides or combinations of two or more of these in the form of compounds such as spinels or as Or solid solution glass ceramics.

[0304] The present disclosure also contemplates the use of glass and glass ceramics. However, for certain applications, it may be desirable to use non-glass-based ceramics. For example, certain glasses may react with human or animal body fluids, thereby reducing the biostability of the feedthrough. Therefore, non-glass-based ceramics may be selected to improve the biostability of the formed feedthrough.

[0305] The ceramic may be formed around the elongate electrical conductor by any suitable process, given the degree of bonding and hermeticity required for the intended application.

[0306] Typical processes include slip casting, gel casting, low pressure-low viscosity thermoplastic injection molding, fluidized bed direct transfer, low stress casting, zero pressure casting, gravity feed casting or casting without external pressure application and other alternatives that will be obvious to those skilled in the art. Preferably, these processes do not expose the longitudinal electrical conductors to significant pressures that may cause deformation and misalignment. Preferably, these processes are carried out at less than 2 atmospheres (absolute), more preferably less than 1.8 atmospheres (absolute) or less than 1.5 atmospheres (absolute); and even more preferably at ambient atmosphere (i.e., 1.0 atmosphere (absolute)) and even more preferably under vacuum. Within the scope of the present invention, conventional ceramic powder injection molding is typically operated at pressures of 10s or 100s atmospheres and is therefore not suitable for preparing feedthroughs.

[0307] Desirable features to achieve high density and airtightness in the composite are:

[0308] ·Void-free casting

[0309] Stress-free green body

[0310] Uniform green density throughout the green body

[0311] A co-sintering process can be used to densify a green body in which a ceramic matrix encapsulates an array of metal pins. The selection of co-sintering process parameters depends on the metal-ceramic system selected. Typically, the temperature can be in the range of 1050°C to 1800°C for peak sintering temperature. The environment can also be changed from atmospheric to inert to other atmospheres or vacuum. In some cases, if a binder is used, the green body monolith can be passed through an air oven for binder burnout and subsequently transferred to a high temperature furnace for sintering. In some cases, pressure-assisted sintering can also be used.

[0312] Example 1

[0313] Alumina was used as the insulating ceramic and platinum wire was used as the electrical conductor. The electrical conductor forms an electrically conductive via in the feedthrough. Fig.10 The entire process up to and including embedding the elongate electrical conductor 1 in the ceramic is shown.

[0314] A wire bonding process is used to bond platinum wire 1 to the conductor-frame assembly precursor 24, 25, 26. The individual lead frames 25, 26, 27 are then arranged into a desired pattern to form an assembly 28 of lead frames 25, 26, 27. The assembly 28 is then placed in a mold / mould (schematically indicated at 29) and subsequently the ceramic matrix is ​​cast using a gel casting method.

[0315] Gel casting of alumina was accomplished by preparing a 99.9% pure alumina slurry with acrylic dispersant and water followed by the addition of monomer methacrylamide and cross-linker polyethylene glycol dimethylacrylate. The solid loading of alumina was approximately 40% by volume.

[0316] Alternative gel casting methods may be used, as will be apparent to those skilled in the art. Gel casting methods for preparing zirconia ceramics, zirconia toughened alumina (ZTA) ceramics, yttria-tetragonal zirconia polycrystalline (3Y-TZP) alumina ceramics and / or other ceramics may be used. For example, those described in US Pat. No. 5,028,362 and / or US Pat. No. 6,066,279 may be used.

[0317] After co-firing, individual feedthroughs 20 may subsequently be cut from the co-fired monolith, or in other cases may be individually over-moulded based on the design.

[0318] This process allows very thin (<400 μm) insulator plates to be fabricated in a closely spaced (<250 μm pitch) relationship with complete conductors passing therethrough.

[0319] Example density

[0320] The table below shows the density distribution of a ceramic matrix using a forming system that takes samples at intervals of at least 0.002 inches (50 μm). As can be seen, densities of >98% are achieved with very low standard deviations.

[0321]

[0322] It will be appreciated that good theoretical density is achieved due to the low porosity resulting from the formation method employed. Fig.24In the prior art of ceramic lamination around the conductor 1 in the ceramic body 12 (see FIG. 23 ), since the conductor 1 is not uniform and extends into the ceramic 12, a region with a larger porosity and a lower density may be formed. However, when a feedthrough is manufactured according to the present disclosure (see Fig.24 ), since the conductor is homogeneous with a constant cross-section, there are no areas of reduced density and increased porosity / there are fewer areas of reduced density and increased porosity.

[0323] Because the density of the ceramic around the conductor is more uniform, there are fewer stress risers within the ceramic. In turn, fewer stress risers can lead to increased hermeticity and / or a longer period of time for maintaining a high degree of hermeticity. In addition, because there are fewer stress risers, further miniaturization can be achieved because smaller-sized feedthroughs can have sufficient integrity.

[0324] A known alternative to the ceramic laminate of Figure 23 is to use platinum ink, which has similar problems as ceramic laminates.

[0325] Example SEM images

[0326] Fig.11 The cutting interface of a high-density feedthrough made by this process is shown, using a single piece of aluminum oxide substrate 32 embedded in the The conductors are arranged in layers and the measurements consisting of the conductor positions are shown. The figure shows that the process of the present disclosure can easily achieve a conductor spacing within a layer of approximately The standard deviation is less than The spacing between the conductor layers is approximately The standard deviation is less than The interlayer spacing is determined by the leadframe thickness and any spacing between leadframes, and this example is not optimized for tight spacing.

[0327] Fig.12 The phase boundary 35 between the platinum and the alumina matrix is ​​shown to be sharp, showing no signs of chemical diffusion or metal degradation.

[0328] Exemplary Conductor Uniformity

[0329] FIG16 shows a prior art feedthrough comprising a metal conductor in a ceramic matrix. In this case, the feedthrough is prepared according to the method of US8,698,006. FIG16 (a), (b) and (c) show images where the surface of the conductor has been polished to different depths. Obviously, the surface shown is in the plane of the conductor.

[0330] The diameter of the conductor is approximately 0.002 inches (50 μm). When using the method of US 8,698,006, it is expected to obtain a conductor with a uniform cross section, however, it can be seen that the cross section is not uniform because the edges of the conductor are jagged or have a zigzag profile. Therefore, it is clear that the conductor does not have a smooth or uniform surface. As shown in Figure 16, for a 50 μm pin, the deviation caused by slip / deformation can be as high as 25 μm.

[0331] Fig.17 A feedthrough comprising a metal conductor in a ceramic matrix prepared using the present method is shown. When observing these SEM images, it should be noted that the ceramic matrix (ZTA) is very hard. Therefore, it is difficult to perfectly polish the interface between the ceramic and the Pt pin. The visible porosity and wear are artifacts of the polishing process and not characteristics of the feedthrough. However, it is clear that the wire is not zigzag.

[0332] Furthermore, it can be seen that the conductors are parallel to within 1°. The deviation shown is exaggerated here due to polishing artifacts. No significant slip is observed in the pins. (The same deviation also appears in the previous process (Figure 16), however, it is masked by the total slip deviation.)

[0333] The effects of polishing artifacts are particularly noticeable when viewing X-ray images (since no polishing is required for taking the X-ray images). Fig.18 and Fig.19 An X-ray image is shown in . Fig.18 and Fig.19 CT scan (X-ray) of a 0.002 inch (50 μm) diameter wire 1 in a ZTA ceramic matrix 12.

[0334] Fig.18 The length of the wire in the image is approximately 2.4 mm (0.1 in). The shadow and light pattern of the wire is an artifact of the X-ray technology that makes the diameter of the wire appear slightly larger than it actually is. However, it can be clearly seen that the wire is actually parallel and straight throughout the visible 2.4 mm length.

[0335] Fig.19 The in-plane position accuracy is shown to be within approximately 0.0005 inches (12.7 μm), which is shown in the following reference Figure 20 to Figure 22 Discuss in more detail.

[0336] Example Precise Wire Placement

[0337] Fig. 20 The conductor position tolerance is shown as + / - 50 microns, and the conductor diameter is 50 microns. Fig. 20 In ZrO 2A Pt pin 1 having a diameter of 0.002 inches (50 μm) is shown in the insulating ceramic 12. The surface is cut and polished. The solid line corresponds to the "ideal" or expected position and the dashed line corresponds to the measured position. These measurements show that in the y plane (eg Fig. 20 The deviation from the expected position is less than 0.0005 inches (12.7 μm) in the x-plane (as shown in the figure). These measurements also show that Fig. 20 The deviation from the desired position within 0.0008 inches (20.3 μm) is less than 0.0008 inches (20.3 μm).

[0338] Fig.21 It shows that ZrO 2 2 mil diameter Pt pin in ceramic body. The surface is cut and de-polished. Fig.21 In the , the deviation from the "ideal" or desired position (indicated by the dashed line) is mostly the result of surface state artifacts introduced by the sawing process due to the softness of Pt. The deviation from the desired position is less than 0.0002 inches (5.1 μm).

[0339] Fig. 22 A 0.015" (381 μm) diameter Pt pin in a ZTA ceramic body is shown. Again, the surface was cut and de-polished. In this example, no deviation from the "ideal" or desired position was observed.

[0340] Clearly, by better controlling the minimum design spacing between electrical paths, designers can design the paths closer together, thereby achieving further miniaturization.Thus, it is clear that because the disclosed method enables more precise placement of conductors, it also enables conductors to be placed closer together in a feedthrough design.

[0341] Example Conductor Density

[0342] A 10 mil inter-conductor spacing is shown, using a 2 mil diameter wire. In this example, 120 conductors are incorporated into the feedthrough at this conductor density. This is a significant improvement over the prior art, resulting in an overall 5x reduction in the area of ​​the feedthrough.

[0343] As will be apparent, this corresponds to 1 conductor / 100 mils. 2 density.

[0344] In a further example (using a 2 mil diameter conductor), a 235 micron (235 μm, 9.2 mil) center-to-center spacing between conductors is shown. In other examples, a 200 micron (200 μm, 7.9 mil) center-to-center spacing between conductors is shown. In an even further example, a 135 micron (135 μm, 5.3 mil) center-to-center spacing between conductors is shown. In another example, a 100 micron (100 μm, 3.9 mil) center-to-center spacing between conductors is achieved. In another example, the center-to-center spacing between conductors is 93 microns (93 μm, 3.66 mil). These spacings correspond to 1 conductor / 85 mil, respectively. 2 , 1 conductor / 62 mils 2 , 1 conductor / 28 mils 2 , 1 conductor / 15 mil 2 and 1 conductor / 13 mils 2 Conductor density.

[0345] Thus, in the example, a conductor / 23 mil is achieved. 2 The conductor density corresponds to a conductor center-to-center spacing of 4.8 mils or less. In other examples, it is contemplated that the described method can be used to achieve a conductor density of 1 conductor / 12 mils. 2 or even 1 conductor / 9 mils 2 The conductor density corresponds to a conductor center-to-center spacing of 90 microns (90 μm, 3.5 mils).

[0346] Fig.21 An SEM micrograph of a feedthrough having a 2 mil (50.8 μm) diameter conductor in a ceramic body (prepared according to the methods and materials of Example 1) is shown. Since the ceramic matrix is ​​very hard and difficult to polish, the visible porosity and wear are artifacts of the polishing process and not characteristics of the feedthrough. Fig.21 In the image of FIG. 1 , distance a is 2 mils (50.8 μm) and distance b is also 2 mils (50.8 μm). It will also be apparent that the diameter of the conductor is 2 mils (50.8 μm). It will also be apparent that the minimum distance between the surfaces of adjacent electrical conductors in a planar cross section of the ceramic body is 2 mils (50.8 μm). Thus, in this feedthrough, the center-to-center spacing between conductors is 4 mils (101.6 μm). This corresponds to 1 conductor / 16 mils. 2 (10323μm 2 ) density.

[0347] therefore, Fig.21The realization of a feedthrough having a combination of small conductor diameter, a small minimum distance between surfaces of adjacent electrical conductors, a small center-to-center spacing between conductors, and a high conductor density is shown. Such a feedthrough can be realized using the present method because low pressure casting techniques enable the use of smaller diameter (i.e., more fragile) conductors while reducing the risk of deformation during component formation.

[0348] Example Conductor Thinness / Thickness

[0349] Conductors as small as 0.002 inches in diameter are used to form feedthroughs in the described methods. It is contemplated that conductors as small as 0.001 inches in thickness can be readily used to form feedthroughs in the described methods. Further, it is contemplated that conductors thinner than 0.001 inches can be used to form feedthroughs in the described methods.

[0350] In some cases, it may be preferable to use thinner conductors.

[0351] In other cases, it may be preferable to use thicker conductors. In particular, when conductors are thicker, they can support higher electrical requirements. For example, higher voltage and / or current requirements.

[0352] Fig.12 A polished cross section of a 380 μm (15 mil) diameter platinum pin 33 co-sintered in an alumina substrate 34 is shown. Fig.11 and Fig.12 It is shown that the present disclosure is capable of using multiple size conductors (wires / pins) embedded and co-sintered in a fully dense ceramic matrix that is gas-tight over the length of the embedded conductors.

[0353] Example air tightness test

[0354] The standard size and high density feedthroughs manufactured by this process have a hermeticity of less than 1×10 -9 mbar-l / sec.

[0355] In one example, less than 1×10 -10 In another example, less than 1×10 -11 mbar-l / sec. These measured values ​​correspond to an excellent hermetic seal.

[0356] When measuring these air tightnesses, MIL-STD-883 Test Method 1014 and Test Condition A are used. 4 agreement.

[0357] Example Conductivity Test

[0358] The resistivity / conductivity of a 0.015 inch (381 μm) diameter, Pt (90% wt) / Ir (10% wt) pin was measured. The data is shown in the table below. It can be seen that the measured conductivity is high, while the measured resistivity is low. For example, the resistivity is about 1 / 5 of the resistivity reported in Kyocera's document US2013 / 0032382 (compared to the 5% composition in Table 5; note that the prior art uses the unit Ω.m, while the data below uses the unit Ω.cm.

[0359] sample Average resistivity (Ω.cm) Average conductivity (S / cm) sintering 4.00742E-05 25187.04809 Green 3.16756E-05 31648.54812

[0360] Example Precise Conductor Placement - Parallelism of Pins

[0361] When forming feedthroughs using the disclosed method, it has been possible to achieve feedthroughs with conductors that are parallel to within 0.5° of each other. This is true for feedthroughs with thicknesses ranging from 750 micrometers (750 μm, 30 mils) to 1.6 mm (63 mils).

[0362] Example Feedthrough Thickness

[0363] Using the disclosed method, feedthroughs with thicknesses ranging from 750 micrometers (750 μm, 30 mils) to 1.6 mm (63 mils) were prepared. These feedthroughs had good hermeticity, as described above.

[0364] As will be apparent to one skilled in the art, feedthroughs having a wide range of thicknesses may be prepared using the disclosed methods. However, for certain applications, it may be desirable to have a feedthrough of a certain thickness to achieve the desired hermeticity.

[0365] Determining Conductor Density

[0366] refer to Fig.25 The mathematical method used to determine the conductor density is illustrated in Fig.25 Four conductors 1 are shown in . The view is a cross-sectional view through the feed-through.

[0367] The conductor density can be conceptually analyzed by a and b Since the square has a conductor in each corner, the conductors are given a value of 1 / 4 (each conductor is in four conceptually similar squares), and the conductor density is one conductor / ab area. For example, if a = 4 mils and b = 4 mils, then the density will be one conductor / 16 mils 2 .

[0368] Of course, you can use the edge c and dThe conductor density is calculated by c and d The size of the square is equal to the size of the square with sides a and b). In this case, the square cd also contains a conductor, and the density will be one conductor / cd area. For example, if c = 4 mils and d = 4 mils, then the density will be one conductor / 16 mils 2 .

[0369] Although not shown, within a given region, conductors on the edge of the region will be counted as 1 / 2.

[0370] Using this method, feedthroughs with high density over large cross-sectional areas can be prepared. For example, areas greater than 23 (0.014838), 100 (0.064516), 250 (0.16129), 500 (0.32258), 1000 (0.64516), 2000 (1.29032), 4000 (2.58054), 6000 (3.87096), 10000 (6.4516) mils 2 (mm 2 ).

[0371] Final Limit

[0372] When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof (such as "including" and "including") mean that the specified features, steps or integers are included. These terms should not be interpreted as excluding the presence of other features, steps or components.

[0373] The features disclosed in the preceding description or in the appended claims or in the drawings, expressed in their specific form or according to means for performing the disclosed functions or methods or processes for achieving the disclosed results, may, where appropriate, be used alone or in any combination of these features to realize the invention in its various forms.

Claims

1. A sealed feedthrough, comprising: Ceramic body; as well as a plurality of solid metal wire electrical conductors embedded in the ceramic body, each of the plurality of solid metal wire electrical conductors being a non-bent solid metal wire electrical conductor, wherein the plurality of solid metal wire electrical conductors traverse the ceramic body to provide a feed-through therethrough, wherein the density of the solid metal wire conductors exceeds 1 conductor / 23 mils in a planar cross-section of the ceramic body 2 .

2. The sealed feedthrough according to claim 1, wherein: Each of the plurality of solid metal wire conductors is parallel to one another within 2°, or each of the plurality of solid metal wire conductors is evenly spaced within the greater of the following tolerances: ±5% or 0.002 inches.

3. The sealed feedthrough of claim 1, wherein: The plurality of solid metal wire electrical conductors include at least one planar array of solid metal wire electrical conductors defining a plane, and at least one solid metal wire electrical conductor that is not parallel to the plane.

4. The sealed feedthrough of claim 1, wherein: The ceramic body includes one or more walls extending from a base, and at least one of the plurality of solid metal wire electrical conductors is mounted to traverse the ceramic body from the base to the one or more walls.

5. The sealed feed-through according to any one of claims 1 to 4, wherein: The ceramic body has a density of at least 95% of the theoretical bulk density with a standard deviation of less than 1.0%.

6. The sealed feed-through according to any one of claims 1 to 4, wherein: The ceramic body is monolithic.

7. The sealed feed-through according to any one of claims 1 to 4, wherein: The density of the solid metal wire electrical conductors is no greater than 1 conductor / 9 mils in a planar cross-section of the ceramic body. 2 .

8. The sealed feed-through according to any one of claims 1 to 4, wherein: The surface of the first solid metal wire conductor is at least 40 μm away from the surface of the second solid metal wire conductor in a planar cross-section of the ceramic body.

9. The sealed feed-through according to any one of claims 1 to 4, wherein: A surface of the first solid metal wire electrical conductor is within 0.0038 inches of a surface of the second solid metal wire electrical conductor in a planar cross-section of the ceramic body.

10. The sealed feed-through according to any one of claims 1 to 4, wherein: The density of the solid metal wire electrical conductors is no greater than 1 conductor / 9 mils in a planar cross-section of the ceramic body. 2 ; and the diameter of the solid metal wire conductor is less than 0.0015 inches, or between 0.020 inches and 0.040 inches.

11. The sealed feed-through of claim 10, wherein: The solid metal wire electrical conductor has a diameter less than 0.001 inches, or between 0.020 inches and 0.040 inches.

12. The sealed feed-through of claim 10, wherein: The solid metal wire electrical conductor has a diameter less than 0.0005 inches, or between 0.020 inches and 0.040 inches.

13. A hermetic feed-through as in claim 1 wherein a plurality of said solid metal wire electrical conductors embedded in said ceramic body traverse said ceramic body in a non-coplanar relationship.

14. The sealed feed-through of claim 13, wherein: The plurality of solid metal wire electrical conductors include at least one planar array of solid metal wire electrical conductors defining a plane, and at least one solid metal wire electrical conductor that is not parallel to the plane.

15. The sealed feed-through of claim 13, wherein: The ceramic body includes one or more walls extending from a base, and at least one of the plurality of solid metal wire electrical conductors is mounted to traverse the ceramic body from the base to the one or more walls.

16. The sealed feed-through according to any one of claims 13 to 15, wherein: The ceramic body has a density of at least 95% of the theoretical bulk density with a standard deviation of less than 1.0%.

17. The sealed feed-through according to any one of claims 13 to 15, wherein: The ceramic body is monolithic.

18. The sealed feed-through according to any one of claims 13 to 15, wherein: The density of the solid metal wire electrical conductors is no greater than 1 conductor / 9 mils in a planar cross-section of the ceramic body. 2 .

19. The sealed feed-through according to any one of claims 13 to 15, wherein: The surface of the first solid metal wire conductor is at least 40 μm away from the surface of the second solid metal wire conductor in a planar cross-section of the ceramic body.

20. The sealed feed-through according to any one of claims 13 to 15, wherein: A surface of the first solid metal wire electrical conductor is within 0.0038 inches of a surface of the second solid metal wire electrical conductor in a planar cross-section of the ceramic body.

21. The sealed feed-through according to any one of claims 13 to 15, wherein: The density of the solid metal wire electrical conductors is no greater than 1 conductor / 9 mils in a planar cross-section of the ceramic body. 2 ; and the diameter of the solid metal wire conductor is less than 0.0015 inches, or between 0.020 inches and 0.040 inches.

22. The sealed feed-through of claim 21, wherein: The solid metal wire electrical conductor has a diameter less than 0.001 inches, or between 0.020 inches and 0.040 inches.

23. The hermetic feedthrough of claim 21, wherein: The solid metal wire electrical conductor has a diameter less than 0.0005 inches, or between 0.020 inches and 0.040 inches.

24. A medical device comprising the sealed feed-through of any one of claims 1 to 23.

25. A green body for co-firing to form a hermetic feed-through, the hermetic feed-through comprising: Raw ceramic body; as well as a plurality of solid metal wire electrical conductors embedded in the ceramic body, each of the plurality of solid metal wire electrical conductors being a non-bent solid metal wire electrical conductor, wherein the plurality of solid metal wire electrical conductors traverse the ceramic body to provide a feed-through therethrough, wherein the density of the solid metal wire conductors exceeds 1 conductor / 23 mils in a planar cross-section of the green ceramic body 2 .

26. A green body for co-firing to form the hermetic feedthrough of claim 25 wherein a plurality of said solid metal wire electrical conductors embedded in said green ceramic body traverse said green ceramic body in a non-coplanar relationship.

27. A method of forming an assembly of electrical conductors, the electrical conductors being at least partially embedded in a ceramic or ceramic precursor matrix, the method comprising the steps of: fixedly attaching the plurality of elongated electrical conductors to the frame to form a conductor-frame assembly including the plurality of elongated electrical conductors; introducing a fluid ceramic or ceramic precursor into the cavity at a pressure of less than 2 atmospheres to form a self-supporting body, wherein at least a portion of the elongated electrical conductor is embedded in the self-supporting body, wherein the diameter of the elongated electrical conductor is less than 0.0015 inches, or between 0.020 inches and 0.040 inches, and wherein The viscosity of the fluid ceramic or ceramic precursor is -1 The strain rate is 0.05 to 10.0 Pa.s, and the solid loading of the fluid ceramic or ceramic precursor is in the range of 10 to 80 volume %.

28. The method of claim 27, wherein: The diameter of the elongated electrical conductor is less than 0.001 inches, or between 0.020 inches and 0.040 inches.

29. The method of claim 27, wherein: The diameter of the elongated electrical conductor is less than 0.0005 inches, or between 0.020 inches and 0.040 inches.

30. The method of claim 27, comprising the steps of: d) fixedly attaching each of the first set of elongate electrical conductors to the first set of frame portions via an end of the elongate electrical conductor; e) securing a second set of frame sections to said first set of frame sections in a fixed relationship; f) fixedly attaching each of the second set of elongate electrical conductors by one end to the second set of frame portions and by another end to either the first set of frame portions or the second set of frame portions.

31. The method of claim 27, wherein: Fixedly attaching a plurality of elongated electrical conductors to the frame includes using diffusion bonding, mechanical fastening, adhesives, laser assisted diffusion bonding, or welding to join the elongated electrical conductors to a metal region of the frame.

32. The method of claim 27, wherein: The fluid ceramic or ceramic precursor is introduced by slip casting, gel casting, low pressure-low viscosity thermoplastic injection molding, fluidized bed direct transfer, low stress casting, zero pressure casting, gravity feed casting, or casting without applying external pressure.

33. The method of claim 32, wherein: The fluid ceramic or ceramic precursor is introduced by slip casting, gel casting, low stress casting, zero pressure casting, gravity feed casting or casting without applying external pressure.

34. The method of any one of claims 27 to 33, wherein: The self-supporting body is formed in the cavity as a green ceramic body that is fired to co-sinter the ceramic to the elongated electrical conductor to provide a gas-tight bond between the ceramic and the elongated electrical conductor.

35. A feedthrough prepared by the method of any one of claims 27 to 34.

36. Use of a fluid ceramic or a fluid ceramic precursor in a method of forming an assembly of an electrical conductor as claimed in any one of claims 27 to 34, wherein: The fluid ceramic or fluid ceramic precursor is introduced into the cavity at a pressure of less than 2 atmospheres to form a self-supporting ceramic body.

37. The use according to claim 36, wherein Prior to introducing the fluid ceramic or the fluid ceramic precursor, a conductor frame assembly traverses the cavity.

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