This disclosure generally relates to electrical components for hermetically sealed devices.
Various systems require electrical coupling between electrical devices disposed within a sealed enclosure or housing and devices or systems external to the enclosure. Oftentimes, such electrical coupling needs to withstand various environmental factors such that a conductive pathway or pathways from the external surface of the enclosure to within the enclosure remains stable. For example, implantable medical devices (IMDs), e.g., cardiac pacemakers, defibrillators, neurostimulators, and drug pumps, which include electronic circuitry and one or more power sources, require an enclosure or housing to contain and seal these elements within a body of a patient. Many of these IMDs include one or more electrical components such as, for example, feedthrough assemblies to provide electrical connections between the elements contained within the housing and components of the IMD external to the housing, for example, one or more sensors, electrodes, and lead wires mounted on an exterior surface of the housing, or electrical contacts housed within a connector header, which is mounted on the housing to provide coupling for one or more implantable leads. Existing electrical components may include a substrate that includes vias filled with copper-based alloys.
The techniques of this disclosure generally relate to electrical components that include corrosion-resistant vias in a substrate. The corrosion-resistant vias are filled with a corrosion-resistant alloy capable of bonding to substrates that include ceramics or sapphire and forming a hermetic seal. Such corrosion-resistant alloys may exhibit increased corrosion resistance and reduced porosity relative to existing conductive via fill materials such as, for example, copper-alloys or other materials susceptible to corrosion. Accordingly, electrical components formed according to the methods described herein may allow the construction of packages that have increased corrosion resistance and long-term hermeticity.
In one example, aspects of this disclosure relate to a method of forming an electrical component. The method includes providing a substrate including ceramic or sapphire and forming one or more vias in the substrate. Each of the one or more vias includes an opening at an outer surface of the substrate and one or more sidewalls formed by the substrate. The method further includes disposing a corrosion-resistant alloy in the one or more vias or on the outer surface of the substrate proximal to the one or more vias and reflowing the corrosion-resistant alloy into the one or more vias to form one or more corrosion-resistant vias such that the corrosion-resistant alloy is bonded to the one or more sidewalls.
In another example, aspects of this disclosure relate to an electrical component. The electrical component includes a substrate and one or more corrosion-resistant vias. The substrate includes ceramic or sapphire. The one or more corrosion-resistant vias are disposed in the substrate. Each of the one or more corrosion-resistant vias includes one or more sidewalls formed by the substrate and a corrosion-resistant alloy bonded to the one or more sidewalls.
All headings provided herein are for the convenience of the reader and should not be used to limit the meaning of any text that follows the heading, unless so specified.
The terms “comprises” and variations thereof do not have a limiting meaning where these terms appear in the description and claims. Such terms will be understood to imply the inclusion of a stated step or element or group of steps or elements but not the exclusion of any other step or element or group of steps or elements.
In this application, terms such as “a,” “an,” and “the” are not intended to refer to only a singular entity but include the general class of which a specific example may be used for illustration. The terms “a,” “an,” and “the” are used interchangeably with the term “at least one.” The phrases “at least one of” and “comprises at least one of” followed by a list refers to any one of the items in the list and any combination of two or more items in the list.
As used herein, the term “or” is generally employed in its usual sense including “and/or” unless the content clearly dictates otherwise.
The term “and/or” means one or all of the listed elements or a combination of any two or more of the listed elements.
As used herein in connection with a measured quantity, the term “about” refers to that variation in the measured quantity as would be expected by the skilled artisan making the measurement and exercising a level of care commensurate with the objective of the measurement and the precision of the measuring equipment used. Herein, “up to” a number (e.g., up to 50) includes the number (e.g., 50).
Also herein, the recitations of numerical ranges by endpoints include all numbers subsumed within that range as well as the endpoints (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.)
The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims.
In general, the present disclosure provides various embodiments of an electrical component and a method of forming such electrical component. The electrical component may include a ceramic or sapphire substrate. The electrical component may further include one or more corrosion-resistant vias disposed in the substrate. The one or more corrosion-resistant vias may each include one or more sidewalls formed by the substrate. Each of the one or more corrosion-resistant vias may further include a corrosion-resistant alloy may bonded to the sidewall of the one or more corrosion-resistant vias. The bond between the corrosion-resistant alloy and the one or more sidewalls may provide a hermetic seal. Furthermore, the methods of disposing and reflowing the corrosion-resistant alloy into the vias may reduce porosity and cracking of the via fill materials compared to existing via fill materials and methods. Accordingly, the electrical component described herein can be used as part of devices where corrosion resistance or long-term hermeticity is desired.
Although existing via fill materials such as, for example, copper-based alloys may exhibit good conductivity, such alloys are generally not corrosion-resistant. Additionally, some existing via fill methods/materials may exhibit a level of porosity that may lead to long-term hermeticity failure. In contrast, the corrosion-resistant alloy filled vias described herein may form a bond between the corrosion-resistant alloy fill material and the sidewall from the substrate and may have reduced porosity and cracking of the via fill material.
The substrate 106 may include any suitable material or materials such as, for example, ceramic or sapphire. Ceramics may include, for example, alumina (Al2O3), nanocrystalline yttria-stabilized zirconia (nc-YSZ), or other biostable ceramics. In at least one embodiment, the substrate 106 includes sapphire. In one or more embodiments, the substrate 106 can include a transparent material. The substrate 106 has a thickness that extends between an outer surface 112 and an outer surface 114. The outer surface 112 may be referred to interchangeably as a first major surface and the outer surface 114 may be referred to interchangeably as a second major surface. The substrate 106 may take on any suitable shape or shapes and have any suitable dimensions.
The vias 108 extend from the outer surface 112 to the outer surface 114 and are exposed at such surfaces. Accordingly, the electrical component 102 may be used as a feedthrough, an interposer, or other electrical component. The vias 108 may have any suitable cross-sectional shape or shapes. For example, the vias 108 may have an elliptical cross section. Such elliptical vias may have a single sidewall 116 that defines the outer diameter of the elliptical vias. Further, for example, the vias 108 may have a polygonal cross section. Such polygonal vias may have three or more sidewalls 116. Still further, for example, the vias 108 may have a cross-sectional shape that includes both straight and curved edges such as, for example, a semicircle, a quadrant, arcs, or combinations of curved and polygonal shapes. Vias with such cross-sectional shapes may include two or more sidewalls 116.
The vias 108 are filled with a corrosion-resistant alloy 110. The corrosion-resistant alloy 110 may be bonded to the sidewalls 116. Such bond between the corrosion-resistant alloy 110 and the sidewalls 116 may provide a hermetic seal. The corrosion-resistant alloy 110 may include any suitable material or materials. Such materials may include one or more of, for example, titanium, niobium, nickel, hafnium, etc. In at least one embodiment, the corrosion-resistant alloy 110 includes zirconium alloys. Zirconium alloys may include, for example, Z-61Zr or Z-62Zr. The zirconium alloys may refer to AUFHAUSER ZIRCONIUMALLOYS Z-61Zr or Z-62Zr. The zirconium alloy Z-61Zr may include to 58 to 64 percent by weight zirconium (Zr), 19 to 21 percent by weight nickel (Ni), 10 to 11 percent by weight titanium (Ti), 6 to 8 percent by weight niobium (Nb), and 1 to 2 percent hafnium (Hf). The zirconium alloy Z-62Zr may include to 59.5 to 64.9 percent by weight zirconium (Zr), 19 to 21 percent by weight nickel (Ni), 16 to 18 percent by weight titanium (Ti), and 0.1 to 1.5 percent hafnium (Hf). In at least one other embodiment, the corrosion-resistant alloy 110 includes a titanium alloy TiNi67.
As used herein, “corrosion resistant” or “corrosion-resistant” may refer to materials, alloys, vias, and layers that exhibit less than a 1 micrometer reduction in height of the outer surface when exposed to a 0.9 percent saline solution at 90 degrees Celsius for 10 weeks. In other words, a layer of material removed from corrosion-resistant materials, alloys, vias, or layers due to exposure to a 0.9 percent saline solution at 90 degrees Celsius for 10 weeks will have a thickness of less than 1 micrometer. In general, corrosion-resistant materials and devices remain chemically stable and resist break down or damage due to chemical processes in corrosive environments such as, e.g., marine environments, underground, in the body (e.g., biostable), etc. Accordingly, vias such as vias 108 that are filled with the corrosion-resistant alloy 110 may not include alloys or compositions that may compromise a corrosion-resistance or a biostability of the vias. In other words, vias filled with the corrosion-resistant alloy 110 may be corrosion-resistant vias. While not all alloys that include titanium, niobium, nickel, hafnium, and other elements may be corrosion-resistant, the corrosion-resistant alloys described herein refer to a subset of such alloys that are corrosion-resistant.
The circuitry 104 may include any suitable circuitry or components for incorporating the electrical component 102 in a device. The circuitry 104 may include, for example, multiple layers, substrates, conductive traces, vias, passive components, active components, pads, electrodes, or other electrical components. The circuitry 104 may be soldered or otherwise sealed to the substrate 106. The circuitry 104 may take on any suitable shape or shapes and have any suitable dimensions. Generally, the circuitry 104 may be shaped to fit in a housing of a device.
The alloy bumps 120 include the corrosion-resistant alloy 110. The alloy bumps 120 may further include any suitable material or materials to aid a reflow process. For example, the alloy bumps 120 may include flux, organic binders, fluid, etc. Such materials may aid the corrosion-resistant alloy 110 in filling the vias 108 and bonding to the sidewalls 116. Furthermore, binders and/or fluid may facilitate maintaining the position of the alloy bumps 120 prior to reflow. The alloy bumps 120 may take one any suitable shape or shapes. For example, the alloy bumps 120 may be substantially spherical, discoid, parallelepiped, hemispherical, or other suitable shape. Each of the alloy bumps 120 may be of a size sufficient to fill the vias 108 during a reflow process.
The stencil 122 may be used to secure the position of the alloy paste 124 relative to the vias 108 prior to a reflowing step or process. For example, the stencil 122 may include openings 123 at or near the position of the vias 108. The openings 123 may allow the alloy paste 124 to be deposited in the vias 108 or on the outer surface 112 of the substrate 106 proximal to the vias 108. The stencil 122 may include any suitable materials such as, for example, stainless steel, nickel, etc. In at least one embodiment, the stencil 119 includes stainless steel.
The alloy paste 124 may include the corrosion-resistant alloy 110. The corrosion-resistant alloy 110 may be included in the alloy paste 124 as alloy particles. The alloy paste 124 can include binding agents to hold the alloy particles together. The alloy paste 124 can include any suitable binding agents, e.g., organic binders, solvents, etc. The alloy paste 124 can be dispensed using any suitable dispensing tools and/or nozzles such as, for example, dispenser 128 (see
The alloy paste 124 can be pulled across the stencil 122 and the substrate 106 using any suitable tool or tools. For example, the alloy paste 124 can be pulled across the stencil 122 and the substrate 106 using a squeegee 126. The squeegee 126 may be configured to pull the alloy paste 124 across the stencil 122 and the substrate 106 causing the alloy paste 124 to be deposited in the openings 123 of the stencil 122. After the alloy paste 124 has been deposited in the openings 123 of the stencil 122, the stencil 122 can be removed from the outer surface 112 of the substrate 106 leaving the alloy paste 124 positioned in and proximal to the vias 108. Accordingly, the substrate 106 and the alloy paste 124 of
At 202, the substrate 106 may be provided (see
At 204, one or more vias 108 may be formed in the substrate 106 (see
At 206, the corrosion-resistant alloy 110 may be disposed in the one or more vias 108 or on the outer surface 112 of the substrate 106 proximal to the one or more vias 108. As used herein, the term “proximal to the one or more vias” means that the corrosion-resistant alloy 110 is disposed such that at least a portion of the alloy can flow into one or more openings 117 of the one or more vias 108 when the portion of the alloy is melted. Additionally, the corrosion-resistant alloy may be disposed on the outer surface 112 of the substrate such that the opening 117 of each of the one or more vias 108 is at least partially covered by the corrosion-resistant alloy 110.
The corrosion-resistant alloy 110 may be disposed using any suitable technique or techniques. For example, disposing the corrosion-resistant alloy may include, but is not limited to, disposing a bump array 118 of the corrosion-resistant alloy 110 on the outer surface 112 of the substrate 106 such that the opening 117 of each of the one or more vias 108 is at least partially covered by an alloy bump 120 of the bump array 118 (see
At 208, the corrosion-resistant alloy 110 may be reflowed into the one or more vias 108. Reflowing the corrosion-resistant alloy 110 may include reducing an atmospheric pressure around the substrate 106 and the corrosion-resistant alloy 110. The atmospheric pressure may be reduced to any suitable level, for example, from at least 10-7 Torr to no greater than 10-5 Torr. In at least one embodiment, the atmospheric pressure is reduced to less than 10-6 Torr.
Reflowing the corrosion-resistant alloy 110 may include brazing the substrate 106 and the corrosion-resistant alloy 110. Reflowing the corrosion-resistant alloy 110 may include heating the substrate 106 and the corrosion-resistant alloy 110 to a peak temperature above the liquidus temperature of the corrosion-resistant alloy 110. The liquidus temperature of the corrosion-resistant alloy 110 may be the temperature at which the corrosion-resistant alloy forms solids within a few hours and remains in equilibrium with liquids. The exact liquidus temperature of the corrosion-resistant alloy 110 may depend on its composition (e.g., Z-61Zr, Z-62Zr, TiNi67, or other corrosion-resistant alloy composition). Reflowing the corrosion-resistant alloy 110 may include heating the substrate 106 and the corrosion-resistant alloy 110 to a peak temperature, for example, of at least 10 degrees Celsius greater than the liquidus temperature of the corrosion-resistant alloy 110 and no greater than 150 degrees Celsius greater than the liquidus temperature of the corrosion-resistant alloy 110 or to a peak temperature within any suitable range therebetween. For example, reflowing the corrosion-resistant alloy 110 may include heating the substrate 106 and the corrosion-resistant alloy 110 to a peak temperature in a range from at least 10 degrees Celsius, 15 degrees Celsius, 20 degrees Celsius, 25 degrees Celsius, 30 degrees Celsius, 35 degrees Celsius, 40 degrees Celsius, 45 degrees Celsius, or 50 degrees Celsius greater than the liquidus temperature to no greater than 100 degrees Celsius, 105 degrees Celsius, 110 degrees Celsius, 115 degrees Celsius, 120 degrees Celsius, 125 degrees Celsius, 130 degrees Celsius, 135 degrees Celsius, 140 degrees Celsius, 145 degrees Celsius, or 150 degrees Celsius greater than the liquidus temperature. In at least one embodiment, reflowing the corrosion-resistant alloy 110 may include heating the substrate 106 and the corrosion-resistant alloy 110 to a peak temperature of at least 50 degrees Celsius greater than the liquidus temperature of the corrosion-resistant alloy 110 and no greater than 100 degrees Celsius greater than the liquidus temperature of the corrosion-resistant alloy 110.
Reflowing the corrosion-resistant alloy 110 may include heating the substrate 106 and the corrosion-resistant alloy 110 to a peak temperature that is independent from the liquidus temperature. In at least one embodiment, reflowing the corrosion-resistant alloy 110 may include heating the substrate 106 and the corrosion-resistant alloy 110 to a peak temperature of at least 950 degrees Celsius and no greater than 1050 degrees Celsius. Reflowing the corrosion-resistant alloy 110 may include heating the substrate 106 and the corrosion-resistant alloy 110 at the peak temperature, for example, for at least 10 seconds and no greater than 30 minutes or for any suitable range of time therebetween. For example, reflowing the corrosion-resistant alloy 110 may include heating the substrate 106 and the corrosion-resistant alloy 110 at the peak temperature for a time period in a range from at least 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 1 minute to no greater than 3 minutes, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes. In at least one embodiment, reflowing the corrosion-resistant alloy 110 may include heating the substrate 106 and the corrosion-resistant alloy 110 at the peak temperature for at least 1 minute and no greater than 15 minutes.
Reflowing the corrosion-resistant alloy 110 may form a reaction layer 132 between the corrosion-resistant alloy 110 and the substrate 106. Heating the corrosion-resistant alloy 110 to suitable melting temperatures may allow the corrosion-resistant alloy 110 to displace atoms (e.g., aluminum atoms of substrates that include Al2O3) in the substrate 106 and bond to oxygen atoms of the substrate 106. Such displacement and bonding may form the reaction layer 132.
At 210, the substrate 106 may be shaped. Shaping the substrate 106 may include grinding or polishing one or more surfaces of the substrate 106. Additionally, shaping of the substrate 106 may include grinding or polishing the one or more vias 108. Shaping the substrate 106 may smooth portions of the outer surfaces 112, 114 of the substrate 106 and/or the one or more vias 108. Shaping the substrate 106 may result in one or more planar or curved surfaces.
The invention is defined in the claims. However, below there is provided a non-exhaustive listing of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.
Example Ex1. A method of forming an electrical component. The method includes providing a substrate including ceramic or sapphire and forming one or more vias in the substrate. Each of the one or more vias includes an opening at an outer surface of the substrate and one or more sidewalls formed by the substrate. The method further includes disposing a corrosion-resistant alloy in the one or more vias or on the outer surface of the substrate proximal to the one or more vias and reflowing the corrosion-resistant alloy into the one or more vias to form one or more corrosion-resistant vias such that the corrosion-resistant alloy is bonded to the one or more sidewalls.
Example Ex2. The method of Ex1, where disposing the corrosion-resistant alloy includes disposing a bump array of the corrosion-resistant alloy on the outer surface of the substrate such that the opening of each of the one or more vias is at least partially covered by an alloy bump of the bump array.
Example Ex3. The method of Ex2, where alloy bumps of the bump array are held in place by a stencil while the bump array is disposed on the outer surface of the substrate.
Example Ex4. The method of Ex1, where disposing the corrosion-resistant alloy includes screen printing alloy paste that includes the corrosion-resistant alloy in the one or more vias or on the outer surface of the substrate proximal to the one or more vias.
Example Ex5. The method of Ex1, where disposing the corrosion-resistant alloy includes dispensing an alloy paste that includes the corrosion-resistant alloy in the one or more vias or on the outer surface of the substrate proximal to the one or more vias.
Example Ex6. The method of Ex1, where reflowing the corrosion-resistant alloy includes brazing the substrate and the corrosion-resistant alloy.
Example Ex7. The method of Ex1, where reflowing the corrosion-resistant alloy includes reducing an atmospheric pressure around the substrate and the corrosion-resistant alloy.
Example Ex8. The method of Ex7, where the atmospheric pressure is reduced below 10-6 Torr.
Example Ex9. The method of Ex1, where reflowing the corrosion-resistant alloy includes heating the substrate and the corrosion-resistant alloy to a peak temperature of at least 50 degrees Celsius greater than a liquidus temperature of the corrosion-resistant alloy and no greater than 150 degrees Celsius greater than the liquidus temperature of the corrosion-resistant alloy.
Example Ex10. The method of Ex9, where the substrate and the corrosion-resistant alloy are heated at the peak temperature for at least 1 minute and no greater than 15 minutes.
Example Ex11. The method of Ex1, where reflowing the corrosion-resistant alloy forms a reaction layer between the corrosion-resistant alloy and the substrate.
Example Ex12. The method of Ex1, where the corrosion-resistant alloy includes zirconium.
Example Ex13. The method of Ex1, where the corrosion-resistant alloy includes Z-61Zr or Z-62Zr.
Example Ex14. The method of Ex1, where the substrate includes sapphire.
Example Ex15. The method of Ex1, where reflowing the corrosion-resistant alloy hermetically seals the one or more vias.
Example Ex16. An electrical component that includes a substrate and one or more corrosion-resistant vias. The substrate includes ceramic or sapphire. The one or more corrosion-resistant vias are disposed in the substrate. Each of the one or more corrosion-resistant vias includes one or more sidewalls formed by the substrate and a corrosion-resistant alloy bonded to the one or more sidewalls.
Example Ex17. The electrical component of Ex16, further including a reaction layer adapted to bond the corrosion-resistant alloy and the one or more sidewalls of each of the one or more corrosion-resistant vias.
Example Ex18. The electrical component of Ex16, where the corrosion-resistant alloy includes zirconium.
Example Ex19. The electrical component of Ex16, where the corrosion-resistant alloy comprises Z-61Zr or Z-62Zr.
Example Ex20. The electrical component of Ex16, where the substrate includes sapphire.
All references and publications cited herein are expressly incorporated herein by reference in their entirety into this disclosure, except to the extent they may directly contradict this disclosure. Illustrative embodiments of this disclosure are discussed, and reference has been made to possible variations within the scope of this disclosure. These and other variations and modifications in the disclosure will be apparent to those skilled in the art without departing from the scope of the disclosure, and it should be understood that this disclosure is not limited to the illustrative embodiments set forth herein. Accordingly, the disclosure is to be limited only by the claims provided below.
This application claims the benefit of U.S. Provisional Application No. 63/294,181, filed Dec. 28, 2021, the disclosure of which is incorporated by reference herein in its entirety.
Filing Document | Filing Date | Country | Kind |
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PCT/US2022/054066 | 12/27/2022 | WO |
Number | Date | Country | |
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63294181 | Dec 2021 | US |