Patent ID: 12233477

DETAILED DESCRIPTION

The techniques of this disclosure generally relate to various embodiments of a hermetic assembly. The assembly includes a ferrule that includes a body and a flange that extends from the body. As used herein, the term “ferrule” refers to an element or component that resides between two or more additional components to facilitate physical connection and/or provides structural support of the components in the assembly. The flange is welded to a welding portion of a patterned layer disposed between the flange and a first major surface of a dielectric substrate of the assembly such that the ferrule is hermetically sealed to the dielectric substrate. The hermetic assembly can form a part of a hermetically-sealed package, where a housing of the package can be connected to the ferrule of the assembly.

Some feedthrough assemblies include a dielectric substrate that is connected to a metal battery or housing. Bonding of a dielectric material to a metal material can, however, be challenging. Some techniques for performing such bonding require a bonding surface of the metal battery or housing be polished such that it is extremely smooth. Such smooth bonding surfaces have to be kept clean prior to bonding so that flat, smooth, clean surfaces are presented for bonding.

Other techniques for bonding dielectric and metal materials include bonding or brazing a weld ring to a dielectric wafer and then welding the metal housing or battery to the weld ring. These techniques, however, can still require that bonding surfaces of the dielectric wafer and the weld ring be polished such that they are extremely smooth. And while a brazed weld ring may not require the same level of surface preparation as is required for other types of bonding, brazing is a high-temperature process that can create stress in the materials and limit the process order as well as size, shape, and design of the assembly due to such thermal stresses.

One or more embodiments of the present disclosure provide a hermetic assembly that includes a ferrule having a flange that is welded to a patterned layer disposed on a major surface of a dielectric substrate. The ferrule can be connected to a housing or battery with minimal or no polishing or use of a weld ring. Further, the ferrule can allow for thinner housing sidewalls and provides more area on the dielectric substrate for electronic components as compared to assemblies that utilize weld rings or other attachment techniques. One or more embodiments of the present disclosure can further simplify attachment of a housing to the dielectric substrate of the hermetic assembly. Further, the ferrule can aid in protecting edges of the dielectric substrate and also isolate the substrate from some external loads that can damage the substrate. One or more embodiments of ferrules described herein may be bonded only to one side of the dielectric substrate without needing to be bonded to the other side of such substrate. Further, bonding of the ferrule to the substrate after components have been disposed on the substrate is possible as high process temperatures typically needed for brazing ferrules to substrates are not necessary.

The various embodiments of hermetic assemblies described herein can be included in hermetically-sealed packages that can be utilized for any suitable application. In one or more embodiments, the hermetically-sealed package can maintain the integrity of a conductive pathway that connects an external contact electrode or device to components disposed within the package while protecting enclosed electronic devices or circuitry from undesired external environmental factors.

The various embodiments of hermetic assemblies and hermetically-sealed packages that include such assemblies can be utilized with any suitable devices or systems, e.g., electronic systems used, e.g., in smartphones, tablets, laptop computers, construction equipment, underwater equipment, implantable medical devices, etc.

FIGS.1-2are various schematic views of one embodiment of a hermetic assembly10. In one or more embodiments, the hermetic assembly10can be a feedthrough assembly as it includes one or more feedthroughs18as is further described herein. The assembly10includes a dielectric substrate12having a first major surface14and a second major surface16, a feedthrough18disposed in the dielectric substrate, and a patterned layer20connected to the first major surface of the dielectric substrate. In one or more embodiments, the patterned layer20can be a patterned conductive layer. The assembly10further includes a ferrule22that has a body24and a flange26extending from the body. The ferrule22is connected to a welding portion28of the patterned conductive layer20that is disposed between the flange26and the first major surface14of the dielectric substrate12such that the ferrule is hermetically sealed to the dielectric substrate.

The dielectric substrate12can include any suitable material or materials. In one or more embodiments, the substrate12can include a dielectric material, e.g., at least one of glass, quartz, silica, sapphire, silicon carbide, diamond, or gallium nitride. Further, the substrate12can include at least one of a biocompatible material or one or more coatings or layers that can provide biocompatibility.

In one or more embodiments, the substrate12can be a transparent substrate. As used herein, the phrase “transparent substrate” refers to a substrate that can transmit a given percentage of electromagnetic radiation incident thereon during use of laser bonding techniques described herein to preferentially heat only a major surface of the substrate (e.g., first major surface14or second major surface16of substrate12), and not an inner bulk of the substrate, thereby creating a bond that has a relatively greater strength than the bulk strength of the substrate. In one or more embodiments, the substrate12can be substantially transparent at a desired wavelength or range of wavelengths. As used herein, the phrase “substantially transparent” means that the substrate transmits greater than 50% of electromagnetic radiation incident on the substrate for a selected wavelength or range of wavelengths, assuming no reflection at the air-substrate boundaries. In one or more embodiments, the substrate12can be substantially transmissive to electromagnetic radiation having a wavelength of at least 200 nm. In one or more embodiments, the substrate12can be substantially transmissive to electromagnetic radiation having a wavelength of greater than 10,000 nm. In one or more embodiments, the substrate12can be substantially transmissive to electromagnetic radiation having a wavelength in a range of 200 nm to 10,000 nm. In one or more embodiments, the substrate12can be substantially transmissive to at least one of UV light, visible light, or IR light.

The substrate12can include any suitable dimensions, e.g., thicknesses. Further, the substrate12can take any suitable shape or shapes. The substrate12can be a single, unitary substrate or multiple substrates joined together using any suitable technique or techniques.

Disposed in the substrate12is the feedthrough18, which can include any suitable feedthrough or feedthroughs that provide an electrical connection between the first major surface14and the second major surface16of the substrate. In one or more embodiments, the assembly10can include an array of feedthroughs18. The hermetic assembly10can include any suitable number of feedthroughs, e.g., 1, 2, 3, 4, 5, 10, 20, or more feedthroughs. Each feedthrough18of the assembly10can be substantially identical in construction. In one or more embodiments, one or more feedthroughs can have characteristics that are different from one or more additional feedthroughs. The feedthrough18can include a via30disposed between the first major surface14and the second surface16of the substrate12. A conductive material32can be disposed in the via30to provide an electrical pathway between the first major surface14and the second major surface16of the substrate12.

The feedthrough18can also include an external contact34. In one or more embodiments, the external contact34can be a portion of the patterned conductive layer20that is disposed adjacent the first major surface14of the substrate12. As used herein, the term “adjacent the first major surface of the substrate” means that an element or component is disposed closer to the first major surface of the substrate than to the second major surface of the substrate. In one or more embodiments, the external contact34can be disposed on the first major surface14of the substrate12. The external contact34can be disposed over the via30adjacent the first major surface14of the substrate12. In one or more embodiments, the external contact34can be electrically connected to the conductive material32disposed in the via30. The external contact34can be hermetically sealed to the first major surface14of the substrate12using any suitable technique or techniques.

The via30of the feedthrough18can be any suitable dimensions and take any suitable shape. The size and shape of the via30is predicated on the thickness of the substrate12and the techniques utilized to provide the conductive material32that forms the electrical pathway between the first major surface14and the second major surface16of the substrate12. Exemplary shapes for the via30can include parallel surface walls and/or tapered surface walls. In one or more embodiments where the substrate12has a thickness of approximately 100 to 500 μm, a typical opening for the via30at the first major surface14of the substrate12can be no greater than 500 μm, or no greater than 250 μm, or no greater than 100 micrometers, or no greater than 80 micrometers, or no greater than 50 micrometers, or no greater than 10 micrometers. Of course, the diameter of the via30could be larger (or smaller) than the illustrated examples based on the substrate thickness and/or the techniques utilized to provide the conductive material that forms the electrical pathway. Any suitable technique or techniques can be utilized to form the via30, e.g., drilling, chemical etching, laser etching, etc.

The feedthrough18can also include the conductive material32disposed in the via30to provide a conductive pathway between the first major surface14and the second major surface16of substrate12. The conductive material32can include any suitable conductive material or conductive materials, e.g., copper, titanium, aluminum, chromium, nickel, gold, platinum, composites (e.g., silver-filled epoxies), and combinations thereof. The conductive material32can be disposed in the via30using any suitable technique or techniques to provide a conductive pathway from external contact34to one or more devices or contacts disposed on or adjacent the second major surface16of the substrate12. In one or more embodiments, the conductive material32can be disposed in the via30such that it substantially fills the via. In one or more embodiments, the conductive material32can be disposed in the via along sidewalls of the via and the opening of the via at the first major surface14.

The feedthrough18can also include the external contact34. In one or more embodiments, the external contact34can be adapted to electrically couple the feedthrough18to a conductor or a contact of a device, e.g., a contact of a header of an implantable medical device. Such conductors and contacts can be electrically coupled to the external contact34using any suitable technique or techniques, e.g., soldering, physical contact, welding, etc. The external contact34can include any suitable conductive material or combination of conductive materials, e.g., at least one of copper, silver, titanium, niobium, zirconium, tantalum, stainless steel, platinum, iridium, aluminum, Kovar, or nickel (including clad structures, laminates etc.). In one or more embodiments, the external contact34can include two or more materials, e.g., bi-metals, clad laminates, etc.

Further, the external contact34can take any suitable shape or shapes. In one or more embodiments, the external contact34can take a circular shape in a plane parallel to the first major surface14of the substrate12as shown inFIG.2. In one or more embodiments, the external contact34can take a rectangular shape in the plane parallel to the first major surface14of the substrate12. Further, the external contact34can take any suitable shape or shapes in a plane orthogonal to the first major surface14of the substrate12, e.g., square, tapered, domed, etc. In one or more embodiments, the external contact34can take substantially the same shape as an external contact of one or more additional feedthroughs18. In one or more embodiments, external contact34can take a shape that is different from the shape of an external contact of one or more additional feedthroughs18. Further, in one or more embodiments, one or more external contacts34can include complex shapes such as grooves or channels formed in the contact to facilitate attachment of conductors or electronic devices to the contacts.

The external contact34can also include any suitable dimensions. In one or more embodiments, the contact34can have any suitable thickness in a direction normal to the first major surface14of the substrate12. It is envisioned that for purposes of this disclosure, the dimension of the external contact's thickness is limited only by the fabrication techniques. With that in mind, in one or more example embodiments, a typical thickness can be at least 2 micrometers. In other example embodiments, it may be desirable to have the thickness be less than 10 millimeters, although greater thicknesses are also contemplated in accordance with embodiments of the disclosure. The thickness of the contact34can be the same as or different from the thickness of an external contact of one or more additional feedthroughs. In one or more embodiments, the external contact34can be of sufficient size and thickness to enable laser, resistance, or other welding and joining techniques to be utilized to electrically couple conductors and/or electronic devices to the external contact.

In one or more embodiments, the external contact34can be formed or disposed over the via30on the first major surface14of the substrate12. For purposes of the present disclosure, the terms “form,” forming,” and “formed” will be used interchangeably with the terms “dispose,” “disposing,” and “disposed” respectively, such that the terms are considered to be equivalent. In other words, the external contact34is disposed over the via30such that the contact covers the via and the via is not visible in a plan view of the first major surface14of the substrate12. In one or more embodiments, the external contact34(or any of the external contacts described herein) can be formed separately from the substrate12as a discrete member, or it could be patterned from a conductive sheet or foil.

The external contact34is electrically coupled to the conductive material32that is disposed in the via30. In one or more embodiments, the external contact34is in direct contact with the conductive material32to electrically couple the contact to the conductive material. In one or more embodiments, one or more additional conductive layers (e.g., interlayer40) can be disposed between the external contact34and the conductive material32to electrically couple the external contact to the conductive material.

In one or more embodiments, the external contact34is hermetically sealed to the first major surface14of the substrate12. Any suitable technique or techniques can be utilized to hermetically seal the external contact34to the first major surface14of the substrate12. For example, in one or more embodiments, the external contact34can be hermetically sealed to the first major surface14of the substrate12by a bond35that surrounds the via30as shown inFIG.2. Any suitable technique or techniques can be utilized to form this bond35. For example, in one or more embodiments, the bond35can be formed using a laser to provide a laser bond. By surrounding the via30with the bond35that hermetically seals the external contact34to the first major surface14of the substrate12, the via is also protected from the external environment. The electrical coupling between the external contact34and the conductive material32disposed in the via30is, therefore, protected, and the integrity of this electrical pathway from the first major surface14of the substrate to the second major surface16can be maintained. In one or more embodiments, the external contact34can also be attached to the first major surface14of the substrate12using bonds in addition to bond35. For example, in one or more embodiments, the external contact34can be attached to the first major surface14by bond35and one or more additional bonds between the external contact34and the first major surface, e.g., point bonds.

In one or more embodiments, the feedthrough18can include an internal contact36disposed adjacent the second major surface16of the substrate12. As used herein, the term “adjacent the second major surface of the substrate” means that an element or component is disposed closer to the second major surface than to the first major surface of the substrate. The internal contact36can include any suitable material or materials, e.g., the same materials utilized for the external contact34or others, and can be formed using any suitable technique or techniques such as sputtering, plating, evaporating, etc. Further, the internal contact36can take any suitable shape or shapes and have any suitable thickness in a direction normal to the second major surface16of the substrate12, e.g., the same shapes and thicknesses as described regarding the external contact34, or other thicknesses and shapes such as conductive traces.

The internal contact36is disposed over the via30on the second major surface16of the substrate12. The contact36can be electrically coupled to the conductive material32disposed in the via30. The arrangement30of the external contact34, the via30and the internal contact36facilitates creation of an electrical pathway between the external side adjacent to the first major surface14and the interior side adjacent to the second major surface16. In one or more embodiments, the internal contact36is hermetically sealed to the second major surface16of the substrate12using any suitable technique or techniques, e.g., by a bond (e.g., laser bond) that surrounds the via30.

Connected to the first major surface14of the dielectric substrate12is the patterned layer20. The patterned layer20can include any suitable conductive or nonconductive material or materials, e.g., at least one of copper, silver, titanium, niobium, zirconium, tantalum, stainless steel, platinum, iridium, aluminum, Kovar, or nickel. In the embodiment illustrated inFIGS.1-2, the patterned layer20is a patterned conductive layer. In one or more embodiments, the patterned conductive layer20can include a foil or foils disposed using any suitable technique or techniques. The patterned conductive layer20can include any suitable layers or sublayers.

Further, the patterned conductive layer20can be disposed in any suitable pattern when connected to the first major surface14of the dielectric substrate12. In one or more embodiments, one or more portions of the patterned conductive layer20can form one or more external contact34of one or more vias18disposed in the dielectric substrate12. Further, the patterned conductive layer20can include one or more welding portions28that can be utilized to connect the ferrule22to the dielectric substrate12as is further described herein.

Any suitable technique or techniques can be utilized to dispose the patterned conductive layer20on or adjacent the first major surface14of the dielectric substrate12. For example, the patterned conductive layer20can be disposed on or adjacent the first major surface14utilizing one or more of photolithography, etching, plasma vapor deposition, chemical vapor deposition, electroplating, laser bonding, etc. In one or more embodiments, the patterned conductive layer20can be connected to the first major surface14by one or more laser bonds59.

In one or more embodiments, the assembly10can include a second patterned conductive layer38disposed on or adjacent the second major surface16of the dielectric substrate12. The second patterned conductive layer38can include any suitable patterned conductive layer, e.g., patterned conductive layer20. In one or more embodiments, one or more portions of the second patterned conductive layer38can provide one or more internal contact36of one or more feedthroughs18. The same design characteristics and possibilities described herein regarding the first patterned conductive layer20can be applied to the second patterned conductive layer38.

The patterned conductive layer20can include any suitable number of layers. For example, the patterned conductive layer20can include a conductive sublayer60and an interlayer40disposed between the conductive sublayer and the first major surface14of the dielectric substrate12. The interlayer40can include any suitable material or materials, e.g., titanium, niobium, tantalum, zirconium, and alloys thereof. Further, the interlayer40can have any suitable dimensions. In one or more embodiments, the interlayer40can have a thickness as measured in a direction orthogonal to the first major surface14of the dielectric substrate12of at least 50 nanometers and no greater than 10 micrometers. The interlayer40can be disposed between the conductive sublayer60and the first major surface14of the dielectric substrate12using any suitable technique or techniques, e.g., the same techniques described herein regarding the patterned conductive layer20. In one or more embodiments, the interlayer40and the conductive sublayer60can be disposed on the first major surface14of the substrate12and then patterned using any suitable technique or techniques. Further, the second patterned conductive layer38can include any suitable number of layers. Although not shown, the second patterned conductive layer38can include one or more conductive sublayers and interlayers disposed between the conductive sublayers and the second major surface16of the dielectric substrate12. Any suitable interlayer or interlayers can be utilized, e.g., interlayer40.

Connected to the dielectric substrate12is the ferrule22. The ferrule22can include any suitable material or materials, e.g., at least one of titanium, niobium, or stainless steel. In one or more embodiments, the ferrule22can include a conductive material. The ferrule22can take any suitable shape or shapes and have any suitable dimensions.

For example, as shown inFIG.2, the ferrule22can have an elliptical shape in a plane parallel to the first major surface14of the substrate12. Further, the flange26can also take an elliptical shape in the plane parallel to the first major surface14of the substrate12.

The ferrule22includes the body24and the flange26that extends from the body. The flange26can be integral with the body24or manufactured separately and attached to the body using any suitable technique or techniques. The flange26can include the same material or materials utilized to form the body24. In one or more embodiments, the flange26and the body24can include different materials.

As mentioned herein, the ferrule22can be connected to the dielectric substrate12using any suitable technique or techniques. As illustrated inFIG.1, the ferrule22is connected to the welding portion28of the patterned conductive layer20that is disposed between the flange26and the first major surface14of the dielectric substrate12such that the ferrule is hermetically sealed to the dielectric substrate. In one or more embodiments, the ferrule22can be connected to the second major surface16of the dielectric substrate12. Further, in one or more embodiments, the ferrule22can be connected to the first major surface14and the second major surface16of the dielectric substrate, e.g., the ferrule can include a second flange (not shown) that can be connected to the second major surface of the dielectric substrate. In one or more embodiments, a major surface42of the flange26contacts the welding portion28of the patterned conductive layer20when the ferrule22is connected to the welding portion. In one or more embodiments, the major surface42of the flange26is substantially parallel to the first major surface14of the dielectric substrate12. As used herein, the term “substantially parallel” means that an angle formed between the major surface42of the flange26and the first major surface14of the dielectric substrate12is less than 10 degrees. Further, a gap between the major surface42of the flange26and the first major surface14of the dielectric substrate12is compatible with the joining techniques utilized to connect the flange to the dielectric substrate.

The flange26can be welded to the welding portion28of the patterned conductive layer20using suitable technique or techniques. In one or more embodiments, the flange26is welded to the welding portion28of the patterned conductive layer20by a weld44. Any suitable welding technique or techniques can be utilized to provide the weld44, e.g., laser welding. Further, the weld44can take any suitable shape or shapes and have any suitable dimensions.

In one or more embodiments, the ferrule22can be electrically connected to the patterned conductive layer20using any suitable technique or techniques. As shown inFIG.1, the assembly10includes a second feedthrough46disposed in the dielectric substrate12that is electrically connected to the flange26of the ferrule22. The feedthrough46can include any suitable feedthrough, e.g., feedthrough18. The feedthrough46includes a via48disposed between the first major surface14and the second major surface16of the dielectric substrate12, and conductive material50disposed in the via. The conductive material50is electrically connected to the welding portion28of the patterned conductive layer20through the interlayer40if present. The welding portion28of the patterned conductive layer20is electrically connected to the flange26of the ferrule22. The second feedthrough46also includes an internal contact52disposed adjacent the second major surface16of the dielectric substrate12and electrically connected to the conductive material50disposed in the via48. As a result, the internal contact52is electrically connected to the ferrule22.

The assembly10can also include one or more electronics or electronic components54disposed adjacent at least one of the first major surface14or the second major surface16of the dielectric substrate12. The electronic component54can include any suitable circuit or component, e.g., at least one of a capacitor, transistor, integrated circuit, including controller or multiplexer, sensor, accelerometer, optical components such as emitters and detectors, etc. Although depicted as including one electronic component54, the assembly10can include any suitable number of electronic components. Further, the electronic component54can be electrically connected to one or more feedthroughs18using any suitable technique or techniques. In one or more embodiments, the electronic component54is electrically connected to one or more feedthroughs18by one or more device contacts56. Such device contacts56can be electrically connected to one or more internal contacts36of feedthroughs18using any suitable technique or techniques. In one or more embodiments, the electronic component54can include one or more test points (e.g., one or more test points362ofFIG.8) disposed on one or surfaces of the electronic component as is further described herein.

As mentioned herein, one or more embodiments of assembly10can include the patterned conductive layer20that is connected (e.g., hermetically sealed) to the first major surface14of the dielectric substrate12using any suitable technique or techniques, e.g., welding, laser welding, laser bonding, diffusion bonding, laser-assisted diffusion bonding, etc. In one or more embodiments, the patterned conductive layer20can be connected to the first major surface14using the laser diffusion bonding techniques described in co-owned U.S. Pat. No. 10,124,559 B2, entitled KINETICALLY LIMITED NANO-SCALE DIFFUSION BOND STRUCTURES AND METHODS. For example, electromagnetic radiation (e.g., light) can be directed through the second major surface16of the dielectric substrate12and focused at an interface between the patterned conductive layer20and the first major surface14to form the laser bond59and laser bonds35of the external contacts34. In embodiments where the interlayer40is present, the electromagnetic radiation can be focused at an interface between the interlayer and the first major surface14.

Any suitable electromagnetic radiation can be utilized to form a bond between one or more portions of the patterned conductive layer20and the first major surface14of the dielectric substrate12. In one or more embodiments, the electromagnetic radiation can include laser light that can include any suitable wavelength or range of wavelengths. In one or more embodiments, the laser light can include light having a wavelength of at least 200 nm. In one or more embodiments, the laser light can include a wavelength of no greater than 10,000 nm. For example, laser light can include UV light, visible light, IR light, and combinations thereof. In one or more embodiments, a UV laser can be utilized to provide light having a wavelength of about 350 nm and a pulse width of 30 ns. In one or more embodiments, the materials for the substrate12and the patterned conductive layer20, and the power level and wavelength of the light used may be selected such that the light may not directly damage, ablate, warp, or cut the substrate and the patterned conductive layer, and such that the substrate and the patterned conductive layer retain their bulk properties.

In general, light can be provided by any suitable laser or laser system. For example, the laser may generate light having a relatively narrow set of wavelengths (e.g., a single wavelength). The light emitted by the laser may form a collimated beam that may not be focused at a particular point. The light emitted by the laser may be focused at interfaces between the patterned conductive layer20and the first major surface14to generate a laser bond.

Although the laser may provide light that has a narrow range of wavelengths, in one or more embodiments, the laser may represent one or more devices that emit light having a wider range of wavelengths than a single typical laser. A wide variety of devices may be used to emit light having a narrow or wide range of wavelengths. In one or more embodiments, the laser may include one or more laser devices including diode and fiber lasers. Laser sources may also include, e.g., TI sapphire, argon ion, Nd:YAG, XeF, HeNe, Dye, GaAs/AlGaAs, CO2, Alexandrite, InGaAs, InGaAsP, Nd:glass, Yb:YAG, or Yb fiber lasers. The laser device may also include one of continuous wave, modulated, or pulsed modes. Accordingly, a wide variety of laser devices may be used in the bonding process. In one or more embodiments, a power level of the laser may be set to approximately 1 W, distributed across the approximate focused beam diameter of 10 μm, with a top hat or Gaussian spatial energy profile.

As mentioned herein, the various embodiments of feedthrough assemblies can be utilized in any suitable device or system. For example,FIG.3is a schematic cross-section view of one embodiment of a hermetically-sealed package100. The package100includes a housing102and the hermetic assembly10ofFIG.1. Although depicted as including the hermetic assembly10ofFIG.1, the hermetically-sealed package100can include any suitable hermetic assembly. In one or more embodiments, the hermetic assembly10can form a part of the housing102. The housing102defines a recess112within which one or more electronic components or circuitry (e.g., electronic component54) can be disposed. Further, the housing102, ferrule22, and dielectric substrate12form a cavity116.

The housing102of the package100can include any suitable dimensions and take any suitable shape or shapes. In general, the housing102is sized and shaped to at least partially surround the electronic device54. In one or more embodiments, the housing102can include one or more sidewalls104that can be connected to the hermetic assembly10using any suitable technique or techniques as is further described herein. The housing102can completely surround and enclose the electronic device54, and the hermetic assembly10can be connected to the housing. In one or more embodiments, the housing102can include an open side or face, and the hermetic assembly10can be connected to the housing within this open side such that the hermetic assembly forms a part of the housing. The housing102can be a unitary housing or can include one or more sections that are joined together using any suitable technique or techniques.

The housing102can include any suitable material or materials, e.g., metal, polymeric, ceramic, or inorganic materials. In one or more embodiments, the housing102can include at least one of glass, quartz, silica, sapphire, silicon carbide, diamond, synthetic diamond, or gallium nitride (including clad structures, laminates etc.). In one or more embodiments, the housing102can include at least one of copper, silver, titanium, niobium, zirconium, tantalum, stainless steel, platinum, iridium, aluminum, nickel, Kovar, or AlMg (including clad structures, laminates etc.). In one or more embodiments, the housing102can include the same material or materials as the dielectric substrate12of the hermetic assembly10.

The package100can include any suitable electronic component54or electronics disposed within the housing102. In one or more embodiments, the electronic component54can include any suitable integrated circuit or device, e.g., a controller, a multiplexer, etc. It should be understood that any of the electronic devices mentioned in this disclosure can be coupled to a power source. Further, the package100can include a second electronic component110disposed in any suitable location within the housing102. The second electronic component110can include any suitable integrated circuit or device. In one or more embodiments, the second electronic component110can include a power source that is adapted to provide power to one or more integrated circuits or devices disposed within the housing102or exterior to the housing. Any suitable power source110can be disposed within the housing102, e.g., one or more batteries, capacitors, etc. The power source110can be rechargeable by electrically connecting the power source to a power supply through the hermetic assembly10. In one or more embodiments, the power source110can be adapted to be inductively charged by an inductive power system that is external to the package100. The power source110can be electrically connected to the electronic component54using any suitable technique or techniques. In one or more embodiments, the power source110can include a hermetically-sealed battery that is connected to the hermetic assembly10using any suitable technique or techniques.

The housing102can be connected to the hermetic assembly10using any suitable technique or techniques. In the embodiment illustrated inFIG.3, an edge58of the body26of the ferrule22is connected to an edge106of the housing102by a bond or weld108. Any suitable technique or techniques can be utilized to form the weld108, e.g., the same techniques described herein regarding the weld44between the flange24and the welding portion28of the patterned conductive layer20. Further, the ferrule22can include an overhang114that is disposed adjacent the edge106of the housing102. In one or more embodiments, the overhang114can be adapted to block energy utilized to form weld108from damaging electronic component54.

As mentioned herein, the ferrule22of the hermetic assembly10can be electrically connected to the patterned conductive layer20via the welding portion28of the patterned conductive layer. As a result, the patterned conductive layer20can also be electrically connected to the housing102of the package100via the ferrule22and its connection to the housing. In one or more embodiments, the ferrule22can be electrically connected to a ground terminal that is, e.g., on the housing102of the package100.

The ferrule22of the assembly10can also include a slot78disposed in the body26of the ferrule. In one or more embodiments, the slot78can extend along the edge58and overhang114of the body26of the ferrule. The slot78can take any suitable shape or shapes and have any suitable dimensions. When the assembly10and the housing102are connected together, the slot78can be adapted to form a vent80with the edge106of the housing. In one or more embodiments, the slot78can be adapted to form the vent80with the edge106and the sidewalls104of the housing102. The vent80can allow backfill gas exchange of the package100before the assembly10is sealed to the housing102. Once gas exchange is completed, the vent80can be sealed with weld108.

For example,FIG.15is a schematic plan view of an outer portion of the package100. As can be seen inFIG.15, a substantial portion of the edge58of the body26of the ferrule22is connected to the edge106of the housing102by the weld108. A portion of the edges58,106are, however, left unwelded such that the vent80is exposed. Gas exchange of the package100through the vent80can be performed. After gas exchange has been completed, the weld122can be completed over the remainder of edges58,106and the vent80to seal the ferrule22to the housing102.

In one or more embodiments, the package100can include an optional second housing118connected to a second edge120of the body26of the ferrule22. All of the design considerations and possibilities regarding the housing102apply equally to the second housing118. The second housing118can be any suitable structure or component to which the assembly10is connected. In one or more embodiments, the second housing118can include a header of an implantable medical device (e.g., header330ofFIGS.5-8). The second housing118can include the same materials as the housing102or different materials.

The second housing118can be connected to the second edge120of the ferrule22using any suitable technique or techniques, e.g., the same techniques described herein regarding the connection of the housing102to the ferrule. In one or more embodiments, the second housing118can be connected to the ferrule22by a weld122that is disposed through the second housing and into the ferrule. Further, the second edge120of the ferrule22can include a second overhang124that is disposed adjacent an edge126of the second housing118.

The second housing118can be electrically connected to the ferrule22using any suitable technique or techniques. In one or more embodiments, the second housing118can be electrically connected to the hermetic assembly10through the electrical connection of the ferrule22to the patterned conductive layer20. Further, the second housing118can be electrically connected to the housing102via the ferrule22.

The package100can be manufactured using any suitable technique or techniques. For example,FIG.4is a flowchart of one embodiment of a method200of forming the hermetically-sealed package100. Although described in regard to the package100, the method200can be utilized to form any suitable hermetically-sealed package.

Method200includes disposing the power source110within the recess112of the housing102at202. In one or more embodiments, the power source110can be a hermetically-sealed battery that has been formed within housing102using any suitable technique or techniques. The patterned conductive layer20can be laser bonded to the first major surface14of the dielectric substrate12at204. Further, at206, the electronic device54can be disposed on the second major surface16of the dielectric substrate12. At208, the flange26of the ferrule22can be welded to the welding portion28of the patterned conductive layer20such that the welding portion is between the flange and the first major surface14of the dielectric substrate12and the ferrule is hermetically sealed to the dielectric substrate. Further, the edge58of the body26of the ferrule22can be connected to the edge106of the housing102(or hermetically-sealed battery) at210using any suitable technique or techniques such that the electronic device54is disposed within cavity116. In one or more embodiments, the weld108can be formed between the ferrule22and the housing102using any suitable technique or techniques. In one or more embodiments, the weld108hermetically-seals the assembly10to the housing102.

When the ferrule22includes the slot78, a portion of the edges58,106can remain disconnected such that the vent80is exposed. In such embodiments, the method200can include a gas exchange between the package100and the environment external to the package. Any suitable gas exchange technique or techniques can be utilized. In one or more embodiments, a vacuum can be applied to the package100such that any internal gases or ambient air can be removed from the package. Optionally, the package100can be subjected to heat while under vacuum to remove any moisture from within the package. In one or more embodiments, the package100can be backfilled by exposing the package to an inert or low-reactive gas such as argon, nitrogen, helium, or combinations thereof, such that the gas enters the package through the vent80. While still in an inert gas environment, the weld108can be disposed over the vent80and between the remainder of the edge58of the body26of the ferrule22and the edge106of the housing102such that the assembly10is hermetically sealed to the housing.

In embodiments where the hermetically-sealed package100includes second housing118, the edge126of such housing can be connected to the second edge120of the body26of the ferrule22at212using any suitable technique or techniques. In one or more embodiments, the weld122can be formed through the edge126of the second housing118and into the second edge120of the body26of the ferrule22. In one or more embodiments where the second housing118is a header (e.g., header308ofFIGS.5-8), the header can be connected to the second edge120of the body26of the ferrule22such that the header is electrically connected to the feedthrough20of hermetic assembly10using any suitable technique or techniques. In one or more embodiments, the gas exchange through vent80can occur prior to or after the second housing118is connected to the second edge120of the body26of the ferrule22.

The various embodiments of feedthrough assemblies described herein can be utilized with any device or system that requires hermetically sealed conductive pathways. For example, one or more embodiments of feedthrough assemblies described herein can be utilized with an implantable medical device or system. In one or more embodiments, the implantable medical device or system can employ one or more leads that may be used with the various embodiments of feedthrough assemblies described herein. Representative examples of such implantable medical devices include hearing implants, e.g., cochlear implants; sensing or monitoring devices; signal generators such as cardiac pacemakers or defibrillators, neurostimulators (such as spinal cord stimulators, brain or deep brain stimulators, peripheral nerve stimulators, vagal nerve stimulators, occipital nerve stimulators, subcutaneous stimulators, etc.), gastric stimulators; or the like. Further, in one or more embodiments, an implantable medical device can include one or more external contacts of a hermetic assembly that can be utilized to directly provide energy to tissue of a patient.

For example,FIGS.5-8are various schematic views of one embodiment of an implantable medical device system300. The system300includes an implantable medical device (IMD)302, a lead304, and a lead extension306.

The IMD302includes a hermetically-sealed package303that includes a housing310, a hermetic (e.g., feedthrough) assembly312that forms a part of the housing, and a header308adapted to receive a proximal portion314of the lead extension306. All of the design considerations and possibilities regarding the hermetically-sealed package100ofFIG.3apply equally to the hermetically-sealed package303of IMD302. Although depicted as include a single hermetic assembly312, the IMD302can include any suitable number of hermetic assemblies.

The proximal portion314of lead extension306includes one or more electrical contacts316that are electrically connected to internal contacts (not shown) at distal connector318of the lead extension. The header308of the IMD302includes internal contacts320(FIGS.6-7) and is adapted to receive the proximal portion314of the lead extension306such that the internal contacts of the header may be electrically connected to the contacts316of the lead extension when the lead extension is inserted into the header.

The system300depicted inFIGS.5-8further includes lead304. The depicted lead304has a proximal portion322that includes contacts324and a distal portion326that includes electrodes328. Each of the electrodes328can be electrically connected to a discrete contact324. The distal connector318of the lead extension306is adapted to receive the proximal portion322of the lead304such that the contacts324of the lead can be electrically connected to the internal contacts of the connector of the extension. Accordingly, a signal generated by the IMD302can be transmitted to tissue of a patient by an electrode328of lead304when the lead is connected to the extension306and the extension is connected to the IMD. In one or more embodiments, a signal received by electrode328of lead304from the patient may be transmitted to a contact320of the IMD302when the lead is connected to the extension306and the extension is connected to the IMD.

It will be understood that lead304can be connected to IMD302without use of an extension306. Any number of leads304or extensions306can be connected to device302. While lead304is depicted as having four electrodes328, it will be understood that the lead can include any number of electrodes, e.g. 1, 2, 3, 4, 5, 6, 7, 8, 16, 32, or 64 electrodes. Corresponding changes in the number of contacts324in lead304, contacts316and internal contacts in connector318of lead extension306, or internal contacts320in header308of device302may be required or desired. As used hereinafter, “lead” will refer to both “leads” and “lead extensions” unless the content and context clearly dictates otherwise.

The IMD302further includes the hermetically sealed package303in which electronics334are disposed. The housing310of the hermetically-sealed package303can include any suitable material or combination of materials, e.g., titanium, glass, sapphire, etc. In one or more embodiments, the housing310can be electrically conductive to provide a ground electrode for the IMD302as is known in the art.

Lead receptacles330,332can be formed in the housing336of the header308. The receptacles330,332can take any suitable shape or shapes and have any suitable dimensions. Although depicted as including two receptacles330,332, the header308can include any suitable number or receptacles, e.g., 1, 2, 3, 4, or more receptacles. Further, the receptacles330,332can be adapted to receive and electrically connect contacts316of the lead extension306(or contacts324of the lead304) to contacts320of the header308. Any suitable number of leads304and lead extension306can be electrically connected to the header308via the receptacles330,332.

The receptacles330,332have internal contacts320positioned to align with and electrically connect with contacts316of the lead extension306and/or contacts324of the lead304when the lead extension or lead is properly inserted into one or both receptacles. The pitch of the internal contacts320ofFIG.6is adapted to allow electrical connection with the contacts316of the lead extension306or contacts324of the lead304.

Electronics334disposed within the package303are adapted to send electrical signals to tissue of the patient, or receive signals from tissue of the patient, through leads operably coupled to the electronics of the IMD302. As used herein, the term “transmitted electrical signals” is used to refer to both the signals sent by electronics334to tissue of the patient or received by the electronics from the tissue of the patient. In one or more embodiments, conductors of IMD302can be electrically connected to internal contacts320of lead receptacles330,332via conductors338of hermetic assembly312that are electrically connected to a patterned conductive layer340of the assembly. For example, in one or more embodiments, conductors338can be electrically connected to the electronics334via a feedthrough that is disposed in a dielectric substrate342of the hermetic assembly312. In one or more embodiments, one or more conductors can be electrically connected to a patterned conductive layer disposed on a second major surface of the dielectric substrate342using any suitable technique or techniques. The feedthrough can include any suitable feedthrough described herein, e.g., feedthrough18of assembly10ofFIG.1. A conductive pathway is, therefore, formed between the internal contacts320of lead receptacles330,332and electronics334. Hermetic assembly312can include any hermetic assembly described herein, e.g., hermetic assembly10ofFIGS.1-3.

In one or more embodiments, each conductor338can electrically connect an internal contact320of the lead receptacles330,332to a discrete channel of the electronics334. As used herein, a “channel” of the electronics is a discrete electronic pathway through which signals may be transmitted independently of another channel. Each channel of the electronics334can be independently connected with a discrete internal contact320of the receptacles330,332, which can be connected with a discrete contact316of the lead extension306or contact324of the lead304, which can in turn be connected with a discrete electrode328of the lead. Accordingly, each channel of the electronics334can be operably connected to a given electrode328of the lead304.

As shown inFIG.8, one or more test points362can be disposed on a surface335of the electronics334(i.e., electronics package or component). such test points362can be utilized to test the electronics334. The test points362can be incorporated into the electronics334as part of a three-dimensional die stack of the electronics package. Although not shown, vertical interconnects such as vias can be disposed through one or more of the electronics334and electrically connected to the test points362. The surface335can be a non-functional surface such as glass with the test points362disposed on the surface and one or more vias disposed through the surface and into the layers of the electronics. In one or more embodiments, the surface335of the electronics334can be an active surface with the test points362disposed directly onto such active surface or on a redistribution layer disposed on the active surface. The test points362can be utilized to access schematic nodes disposed in a top layer or intermediate layers of the package of electronics334or to access schematic nodes disposed on the substrate342that are not disposed within the package.

Such placement of the test points362can reduce or eliminate the need for hybrid test points. Further, because the test points362are on or in the electronics stack, interconnections for such test points do not significantly increase the complexity of the stack. Further, such positioning of the test points362can reduce routing lengths to out-board test points, reduce EMI concerns, and simplify manufacturing. Further, the test points362can simplify burn-in when testing both in panel/wafer form and downstream when the devices are singulated. Also, troubleshooting completed devices can be simplified because the test points362remain formed on the electronics334.

As is also shown inFIG.8, a ferrule344of the hermetic assembly312can include an optional slot378. The slot378can take any suitable shape or shapes and have any suitable dimensions. The slot378can be utilized to form a vent with the housing336to allow for gas exchange between the package303and the environment surrounding the package as is described herein regarding slot78and vent80ofFIG.3.

The hermetic assembly312can be disposed within the header308such that the housing336surrounds the assembly, and the assembly can be connected to a sidewall of the housing310of the IMD302between the header and the housing. In one or more embodiments, the hermetic assembly312can be disposed on any sidewall of the housing310such that the system does not include a header. In one or more embodiments, the hermetic assembly312can be connected to the housing by the ferrule344that is connected to a welding portion346of the patterned conductive layer340that is disposed between a flange354of the ferrule and a first major surface348of the dielectric substrate342such that the ferrule is hermetically sealed to the dielectric substrate. Any suitable technique or techniques can be utilized to hermetically seal the ferrule344to the dielectric substrate342, e.g., the same techniques described herein regarding the hermetically-sealed package100ofFIG.3. For example, the patterned conductive layer340can be connected to the first major surface348of the dielectric substrate342by a laser bond356. And the flange354of the ferrule344can be welded to the welding portion346of the patterned conductive layer340by weld358such that the ferrule is hermetically sealed to the dielectric substrate. Further, the hermetic assembly312can be disposed on a sidewall of the housing310using any suitable technique or techniques, e.g., the same techniques described herein regarding hermetically-sealed package100ofFIG.3.

The header308can be connected to at least one of the hermetic assembly312and the housing310using any suitable technique or techniques, e.g., the same techniques described herein regarding the hermetically-sealed package100ofFIG.3. In one or more embodiments, the hermetic assembly312can include tabs350(FIG.8) that can receive one or more fasteners that extend through openings in the header308and openings352in the tabs and connect the header to the hermetic assembly. Any suitable fasteners can be utilized to connect the header308to the hermetic assembly312.

As mentioned herein, the various embodiments of feedthrough assemblies described herein can be utilized in any suitable device. For example,FIGS.9-10are various views of another embodiment of an implantable medical device400. All of the design considerations and possibilities regarding the implantable medical device300ofFIGS.5-8apply equally to the implantable medical device400ofFIGS.9-10. The device400includes a hermetically-sealed package402having a housing404and a hermetic (e.g., feedthrough) assembly406that forms a part of the housing.

The hermetic assembly406includes a dielectric substrate410and a ferrule412. The ferrule412includes a body414and a flange416extending from the body. The ferrule412is connected to a welding portion418of a patterned conductive layer420that is disposed between the flange416and a first major surface422of the dielectric substrate410such that the ferrule is hermetically sealed to the dielectric substrate. An edge424of the body414of the ferrule412is connected to an edge426of the housing404.

The hermetically-sealed package406also includes a second housing408that is connected to a second edge428of the body414of the ferrule412. Any suitable technique or techniques can be utilized to connect the second housing408to the ferrule412, e.g., the same techniques described herein regarding connection of the housing102and second housing118of the hermetically-sealed package100ofFIG.3. In one or more embodiments, the second housing408includes an external contact430that is adapted to provide an electrical signal to tissue of a patient using any suitable technique or techniques. In one or more embodiments, the external contact430can be electrically connected to the patterned conductive layer420of hermetic assembly406using any suitable technique or techniques.

The IMD400can take any suitable shape or shapes. In one or more embodiments, at least one of the housing404, second housing408, or the dielectric substrate410can have an elliptical cross-section in a plane that is substantially parallel to the first major surface422of the dielectric substrate410. Further, the IMD400can have any suitable dimensions.

The IMD400can further include one or more tines432that are connected to the second housing408using any suitable technique or techniques. In one or more embodiments, one or more of the tines432can be electrically connected to the hermetic assembly406using any suitable technique or techniques.

FIGS.11-12are various views of another embodiment of an implantable medical device (IMD)500. All of the design considerations regarding the implantable medical device300ofFIGS.5-8and the implantable medical device400ofFIGS.9-10apply equally to the implantable medical device500ofFIGS.11-12. The device500includes a hermetically-sealed package502having a housing504and a hermetic assembly506that forms a part of the housing. Although depicted as including a single hermetic assembly506, the implantable medical device500can include any suitable number of hermetic assemblies.

The hermetic assembly506includes a dielectric substrate508and a ferrule510. The ferrule510includes a body512and a flange514extending from the body. As can be seen inFIG.12, the flange516extends from an upper portion516of the body512. The ferrule510is connected to a welding portion518of a patterned conductive layer520that is disposed between the flange514and a first major surface522of the dielectric substrate508such that the ferrule is hermetically sealed to the dielectric substrate. An edge524of the body512of the ferrule510is connected to an edge526of the housing504using any suitable technique or techniques, e.g., welding.

One difference between the IMD500ofFIGS.11-12and the IMD400ofFIGS.9-10is that the IMD500does not include a second housing. Instead, the hermetic assembly506forms the upper portion of the sealed package502of the IMD500. Further, the housing504connected to the ferrule510can be a sealed battery that is electrically connected to the hermetic assembly506using any suitable technique or techniques.

In one or more embodiments, the patterned conductive layer520can include an external electrode528disposed on the first major surface522of the dielectric substrate508as shown inFIG.11. The external electrode528can be electrically connected to electronic component530that is connected to a second major surface532of the dielectric substrate508using any suitable technique or techniques. In one or more embodiments, the external electrode528can be adapted to direct energy (e.g., a signal) to tissue of a patient. In one or more embodiments, the external electrode528can be adapted to receive energy from tissue of the patient, thereby functioning as a sensor. In one or more embodiments, the external electric528can be adapted to direct and receive energy to and from tissue of a patient.

The IMD500can take any suitable shape or shapes. In one or more embodiments, at least one of the housing504or the dielectric substrate508can take a rectangular shape in a plane that is substantially parallel to the first major surface522of the dielectric substrate508. Further, the IMD500can have any suitable dimensions.

As described herein, the various embodiments of hermetic assemblies can be utilized in any suitable application. For example, one or more embodiments of hermetic assemblies can be utilized as an optical window or port that can provide a hermetically-sealed window for viewing of one or more components disposed within a housing connected to the assembly or for emission and detection of electromagnetic radiation that is directed through a dielectric substrate of the assembly. For example, an emitter that is adapted to emit electromagnetic radiation can be disposed within a housing that is in part formed by a hermetic assembly. Such electromagnetic radiation can be directed from within the housing and through a dielectric substrate that is hermetically sealed to a ferrule of the hermetic assembly. Such dielectric substrate, is, therefore, adapted to provide an optical window for the emitter.

FIGS.13-14are various view of one embodiment of a hermetic assembly600. All of the design considerations and possibilities regarding the hermetic assembly10ofFIGS.1-2and the hermetically-sealed package100ofFIG.3apply equally to the hermetic assembly600ofFIGS.13-14.

The hermetic assembly600includes a dielectric substrate602having a first major surface604and a second major surface606. The assembly600further includes a patterned layer608connected to the first major surface604of the dielectric substrate602by a laser bond610, and a ferrule612having a body614and a flange616extending from the body. The flange616is welded to a welding portion618of the patterned layer608that is disposed between the flange and the first major surface604of the dielectric substrate602such that the ferrule612is hermetically sealed to the dielectric substrate.

The hermetic assembly600can be connected to any suitable housing (e.g., housing102of package100ofFIG.3) using any suitable technique or techniques. Further, the hermetic assembly600can be utilized with any suitable system or package, e.g., implantable medical device500ofFIGS.11-12.

The various embodiments of hermetically-sealed packages described herein can include any suitable number of hermetic assemblies. For example,FIG.15is a schematic cross-section view of another embodiment of a hermetically-sealed package700. All of the design considerations and possibilities described herein regarding the hermetically-sealed package100ofFIG.3apply equally to hermetically-sealed package700ofFIG.15. The package700includes a first hermetic assembly710and a second hermetic assembly770. Each of the first and second hermetic assemblies710,770can include any suitable hermetic assembly, e.g., hermetic assembly10ofFIGS.1-2. The package700can include identical assemblies710,770. In one or more embodiments, the first assembly710is different from the second assembly770. Although depicted as including two hermetic assemblies710,770, the package700can include any suitable number of assemblies.

The assemblies710,770can be connected together using any suitable technique or techniques. In one or more embodiments, a ferrule722of the first assembly710is connected to a ferrule772of the second assembly770. In the embodiment illustrated inFIG.15, an edge758of a body726of the ferrule722is connected to an edge766of a body768of the ferrule772by a bond or weld764. Any suitable technique or techniques can be utilized to form the weld764, e.g., the same techniques described herein regarding the weld44between the flange26and the welding portion28of the patterned conductive layer20of the assembly10ofFIGS.1-2.

The hermetic assemblies710,770can form a part of a housing702of the package700. In such embodiments, additional portions of the housing702can be connected to one or both of the assemblies710,770to form a hermetically-sealed enclosure712. In one or more embodiments, the assemblies710,770form the entirety of the housing702and provide the hermetically-sealed enclosure712.

The package700can be utilized for any suitable device or system, e.g., an implantable medical device. The package700can provide such device sensing of electrical signals within a patient in two distinct directions. Further such device can provide more reliable telemetry with external transceivers as signals can be transmitted through one or both assemblies710,770, which may be oriented in different directions. Also, the package700can be utilized with an implantable energy transfer system that can be adapted to receive electromagnetic energy through two or more sides of the housing702via the assemblies710,770.

It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). In addition, while certain aspects of this disclosure are described as being performed by a single module or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of units or modules associated with, for example, a medical device.

In one or more examples, the described techniques may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include computer-readable storage media, which corresponds to a tangible medium such as data storage media (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer).

Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term “processor” as used herein may refer to any of the foregoing structure or any other physical structure suitable for implementation of the described techniques. Also, the techniques could be fully implemented in one or more circuits or logic elements.