Patent Description:
Embodiments presented in this disclosure generally related to in-package optics. More specifically, embodiments disclosed herein relate to frame lids for protection and thermal dissipation for electrical and optical components of an in-package optical assembly.

The speed, size and data processing power of ASICs (Application-Specific Integrated Circuits) have increased tremendously, and a large number of packaging technologies such as <NUM>. 5D and 3D integration of ICs (Integrated Circuits) using interposers and TSVs (Through Silicon Vias) as well as various fan-out technologies are being developed. Electrical components produce waste heat during operation, which can damage or interfere with the operation of electrical or optical components in a packaged optical device. As the currents used to power electrical devices increase, so too does the heat produced by those components.

In addition to <NUM>. 5D or 3D integration of ICs, an ASIC package also includes a heat spreader, Thermal Interface Material (TIM), frame lid and heat sink in order to dissipate the heat generated by the ICs. Typically, thermal interface material is dispensed on the backside of the silicon after chip-attachment, and the heat spreader is assembled on the top. An adhesive material glues the heat spreader leg to the substrate. A heat spreader is conventionally made of Copper and alloy plating or another heat conductive material, and can be manufactured into a desired shape via a stamping method. TIM is typically a flowable material with high thermal conductivity and can include Indium and phase change polymers. After the heat spreader is attached (and any adhesives applied between the lid and the substrate), a curing process at a pre-defined pressure and temperature (e.g., <NUM>-<NUM> degrees C) is used to cure the heat spreader (and any adhesives).

With the need for In Package Optics (optics on the same substrate with ASICs), it is often desirable that the optical packaging be compatible with conventional ASIC packaging in order to leverage the ASIC packaging infrastructure and economies of scale in producing In Package Optics, otherwise the operations and heat of the ASIC may damage the optics or cause the optics to perform erratically. For a conventional ASIC package, a frame lid is mounted above the ASIC in order to provide protection as well as heat dissipation. The electrical connections (e.g., power, ground, I/O) are made though an Interposer and substrate and/or the PCB (Printed Circuit Board). However, optical I/O connections through PCBs are difficult to form.

<CIT> is directed to an example device that includes a first shield to provide thermal isolation between a first component and a heatsink of a second component, and to provide a cooling channel that is thermally isolated from the heatsink to receive an airflow for the first component. A second shield is to provide thermal isolation between the first shield and the heatsink, and to provide a thermal barrier region between the first shield and the second shield.

<CIT> is directed to a chip packaging system, including multiple chips, a substrate, a heat dissipating component, and at least one thermoelectric refrigeration chip. A heat dissipating ring and a heat dissipating lid are provided on the heat dissipating component. One end of the heat dissipating ring is secured to the substrate, and the other end, opposite to the end secured to the substrate. The multiple chips are disposed in space enclosed by the substrate, the heat dissipating ring, and the heat dissipating lid, and all of the multiple chips are separated each other by using a thermal insulation material or by air. One surface of each of the at least one thermoelectric refrigeration chip is a hot end and the other surface thereof is a cold end. The cold end of each thermoelectric refrigeration chip is disposed on a side close to the multiple chips.

<CIT> is directed to a semiconductor device that includes a wiring substrate, a first semiconductor chip mounted on the wiring substrate, and a second semiconductor chip mounted on the wiring substrate. The second semiconductor chip generates less heat than the first semiconductor chip. A heat dissipation plate is arranged on the wiring substrate and partially at a higher location than the first and second semiconductor chips. The heat dissipation plate is connected to the first semiconductor chip and includes an opening formed at a location corresponding to an upper surface of the second semiconductor chip. The upper surface of the second semiconductor chip is entirely exposed from the heat dissipation plate through the opening.

<CIT> is directed to a device for holding a light guide, in particular an optical fiber, preferably a glass fiber, comprising at least one bearing having a reversibly deformable inner bearing section being provided with an opening or passage for the light guide and an outer bearing section which is less deformable than the inner bearing section, wherein the inner bearing section and the outer bearing section are formed and arranged in such a manner that the light guide can be moved within the bearing under deformation of the inner bearing section, such movement of the light guide being limited by the outer bearing section.

Disclosed herein is a platform that includes: a substrate; a first IC (Integrated Circuit) mounted to the substrate; a second IC; a first frame lid mounted to the substrate and defining a cavity with the substrate that encapsulates the first IC and the second IC, the first frame lid comprising: a first roof disposed in a first plane parallel to the substrate, the first roof defining a port providing access to the second IC through the first roof; a foot disposed in a second plane parallel to the first plane and connected to the substrate; and a wall, connecting the first roof to the foot; and a second frame lid mounted to the first roof via a thermal isolator and extending through the port to be in thermal contact with the second IC.

Disclosed herein is a method for attaching a frame assembly to a circuit package comprising a substrate, a first EIC (Electronic Integrated Circuit) mounted to the substrate and a second EIC, in which the method includes: applying an adhesive to the substrate; applying a first thermal interface material to a first surface of the first EIC; applying a second thermal interface material to a second surface of the second EIC; placing a first frame lid onto the circuit package, wherein a foot of the first frame lid contacts the adhesive, a roof of the first frame lid contacts the first thermal interface material, and the second thermal interface material is exposed by a port defined in the roof; placing a second frame lid through the port to contact the second thermal interface material, wherein the second frame lid is thermally isolated from the first frame lid; and curing the adhesive, the first thermal interface material, and the second thermal interface material to bond the first frame lid and the second frame lid onto the circuit package and to seal the port.

Disclosed herein is a frame lid assembly that includes: a first frame lid, including: a foot, disposed in a first plane; a roof, disposed in a second plane parallel to the first plane, the roof defining a port as a first through-hole that is perpendicular to the second plane; a wall, disposed obliquely to the first plane, separating the roof from the foot, the wall defining a slot as a second through-hole that is parallel to the first plane; a second frame lid connected to the first frame lid and thermally isolated from the first frame lid, the second frame lid including: a cap, connected to the roof via a thermal insulator; and a plug, extending perpendicularly from the cap through the port.

A frame assembly may be provided in one or several components to protect a photonic assembly captured within the frame assembly from physical contact, and from thermal effects. The frame assembly includes an opening for an optical fiber or other physical communications channel, which may later be sealed, and one or more thermal contact points for electrical circuits captured inside of the frame assembly to allow heat to be transferred from the electrical circuits to the environment outside of the frame assembly. In some embodiments, in order to create an optical input/output (I/O) for an in-package optics solution, a silicon photonic (SiP) chip is mounted on an edge of an interposer within the frame assembly in order to perform Optical to Electric and Electric to Optical conversion, and an optical connection is made between a Fiber Array Unit (FAU) and the SiP chip. The frame lid design is compatible with the assembly process of attaching the FAU and has an opening to allow optical fibers and other optical leads to come out the frame lid.

In various embodiments, a sealant is applied around the optical connections and the lid and/or substrate to seal the internal components inside the lid, and to secure the optical connections. The sealant may be selected based on its thermal properties so that the curing processes used for the Thermal Interface Material (TIM) and adhesives also cure the sealant. In various embodiments, the seal achieved by the sealant is hermetic (i.e., water tight or air tight).

In some embodiments, the opening may be a slot that leaves an open pathway on an underside of the lid so that the lid may be placed vertically over the internal components and the optical lead. In some embodiments that use an open-slot pathway, a second base component of an insert is positioned between the optical lead and the substrate, so that a gap between the optical lead and the substrate is reduced. In such embodiments, the second base component/insert may be placed prior to connecting or after connecting the optical leads, and may be affixed to the substrate and the lid during curing. In other embodiments, the opening may be defined as a closed shape (e.g., a rectangle, circle, oval, etc.), and the lid slides into position along the optical lead before being secured to the substrate at a desired location.

Some examples, useful for understanding the invention, provide for a one-lid design that couples various components captured in a cavity defined between the frame lid assembly and the substrate with the frame lid, to allow heat transfer from those components to the frame lid and the environment outside of the cavity. Disclosed herein is a two-lid design that decouples heat transfer from one section (e.g., the ASIC die) to another section (e.g., the SiP engine) while providing independent heat dissipation paths for both sections. For example, the ASICs for >50TB systems are expected to dissipate hundreds of Watts of power, and the operation of the components of a SiP may be sensitive to heat. Accordingly, thermal isolation between the ASIC and the nearby SiP is highly desired. Some of the embodiments provide a frame lid that has a first opening for optical connections to the SiP die and a second opening for a second frame lid to connect with the SiP.

The one-lid and two-lid designs each include a frame lid that is attached to the first section of the in-package optic, in which an opening or hole may be defined for the second frame lid to be attached to the second section. The second lid is physically and thermally connected via a TIM to the second section (e.g., the SiP engine) and physically connected to the first lid via a thermal insulator, which (at least partially) thermally isolates the heat dissipation path for the second section from the heat dissipation path for the first section. In some embodiments, the thermal insulation seals (e.g., hermetically) an interior cavity of the in-package optic (defined between the lid and the substrate). In some embodiments, the hole is defined during fabrication of the in-package optic, while in other embodiments, the hole is defined at a later time and resealed by the second lid (e.g., as a patch). In some embodiments, the first lid is cured to the substrate at the same time as the second lid is cured to the first lid using the same curing process, while in other embodiments, the second lid is cured to the first lid before or after curing the first lid to the substrate and using a different curing process (e.g., a different temperature or pressure, light curing). In various embodiments, the first lid and the second lid may be made from the same or from different material, and may be connected to individual cooling or heat dissipation systems that are of the same or of different types. For example, a second lid may be connected to a radiative heat sink, whereas the first lid may be connected to a fluid-based heat sink.

The frame lid used for in-package optics has an opening for optical connections to the SiP die and the design provides protection as well as access to the SiP chip for fiber assembly. In addition, the two lid design allows decoupling of heat transfer from one section (e.g., the ASIC die) to another section (e.g., the SiP engine) while providing heat dissipation paths for both sections. In addition to having cutouts/openings for optical connections, cutouts and openings may be included for other purposes such as epoxy dispense/cure, rework, visioning/inspection, etc..

<FIG> illustrate an optical assembly <NUM> or other circuit package to which a frame lid (discussed in greater detail elsewhere in the present disclosure) may be attached.

<FIG> illustrates a profile view of the optical assembly <NUM>, illustrating a substrate <NUM> to which an interposer <NUM> and adhesive <NUM> are attached on one side. The interposer <NUM> is connect to a first Photonic Integrated Circuit (PIC) <NUM>, a first Electrical Integrated Circuit (EIC) 140a (generally, EIC <NUM>), and a second EIC 140b on an opposite side to where the substrate <NUM> is attached. The interposer <NUM> provides for electrical connectivity between the circuits connected thereto and may include one or more connections to Through Silicon Vias (TSV) defined in the substrate <NUM> to provide electrical connections to devices outside of the optical assembly <NUM>.

The PIC <NUM> is part of a SiP platform, which includes a third EIC 140c connected to the PIC <NUM> and an optical fiber <NUM> (or other optical communications channel) connected to the PIC <NUM>. The PIC <NUM> provides for one or more of the transmission of optical signals (e.g., via a laser and associated modulators and optical amplifiers) and/or of the reception of optical signals (e.g., via a photodiode and associated modulators and optical amplifiers) over the optical fiber <NUM>. The PIC <NUM> may be mounted within a Fan-Out Wafer-Level Package, and the third EIC 140c may be mounted to the PIC <NUM> to drive a laser or other optical component defined in the PIC <NUM>.

Each of the EICs 140a-c is associated with a corresponding TIM 160a-c (generally, TIM <NUM>). The TIM <NUM> may include various materials, such as Indium and phase change polymers, that are selected to conduct heat generated by the associated EIC <NUM> to a frame lid, to thereby dissipate heat from the EIC <NUM> into the external environment. Although illustrated as even layers across the EIC <NUM>, and of even height, in various embodiments the TIM <NUM> may be applied to a sub-portion of the EIC <NUM> and may be applied at different heights/thicknesses to each of the EIC <NUM>. Additionally, one or more EIC <NUM> may omit a corresponding TIM <NUM> in various embodiments.

<FIG> and <FIG> illustrate isometric views of optical assemblies <NUM> with the same elements described in <FIG>. <FIG> illustrates a first arrangement of components on the interposer <NUM>, where the upper surfaces of the first EIC 140a, second EIC 140b, and third EIC 140c are disposed in one plane. <FIG> illustrates a second arrangement of components on the interposer <NUM>, where the upper surfaces of the first EIC 140a and second EIC 140b are disposed in one plane, and the upper surface of the third EIC 140c is disposed in a different plane. Each of the EICs <NUM> may be disposed in the same or different planes based on the relative heights of the EICs <NUM> relative to the interposer <NUM> or substrate <NUM>. A fabricator may compensate for different relative heights of the EICs <NUM> by one or more of: different heights of TIMs, a two-lid design, etc..

The optical assembly <NUM> illustrated in <FIG> is provided for explanatory purposes. The present disclosure is contemplated for use with optical assemblies <NUM> using more or fewer than the illustrated components and in different arrangements than illustrated in <FIG>.

<FIG> illustrate a photonic platform <NUM> using a one-lid design, useful for understanding the invention. In various embodiments, a one-lidded photonic platform <NUM> may be modified into a two-lidded photonic platform <NUM> (as is discussed in relation to <FIG>), for example, when retrofitting, repairing, or inspecting internal components of a one-lidded photonic platform <NUM>.

<FIG> illustrates a profile view with a portion of a one-lidded photonic platform <NUM> cutaway to show details of an optical assembly <NUM> connected thereto. The photonic platform <NUM> includes the components of the optical assembly (such as is illustrated in <FIG>) and a first frame lid <NUM>. The first frame lid <NUM> includes a foot <NUM> in contact with the adhesive <NUM> and (when cured) bonded to the substrate <NUM> via the adhesive <NUM>, a roof <NUM> in contact with the TIM <NUM> of the EIC <NUM> within a cavity <NUM> defined between the first frame lid <NUM> and the substrate <NUM>, and a wall <NUM> that separates the foot <NUM> from the roof <NUM> and defines a slot <NUM> (not visible in <FIG>) as a through-hole that the optical fiber <NUM> passes into/out of the cavity <NUM>. In various embodiments, the adhesive <NUM> forms a bond between the frame lid <NUM> and the substrate <NUM> that is airtight or watertight, and a sealant (not illustrated) is placed in the slot <NUM> to form an airtight or watertight seal so that the cavity <NUM> is hermetically sealed from the external environment when cured.

<FIG> illustrates an isometric view of a frame lid <NUM> as may be used in a photonic platform <NUM> using a one-lid design, illustrating the slot <NUM>. The slot <NUM> is defined in the wall <NUM> as a through-hole that the optical fiber <NUM> may pass. The through-hole for the slot <NUM> runs parallel to the plane of the substrate <NUM>, although the slot <NUM>, due to the angle of the wall <NUM> relative to the foot <NUM> and the roof <NUM>, may be defined in various planes that are nonparallel to the planes in which the foot <NUM> and the roof <NUM> are defined. Although shown as generally circular in <FIG>, the slot <NUM> may be defined with other cross-sectional shapes in other embodiments. Although the wall <NUM> is illustrated with two or more individual surfaces, surrounding a roof <NUM> having a generally rectangular areal section, in other embodiments, the wall <NUM> may be provided with a single surface and in different cross sectional areas (e.g., as the one-sided perimeter of a circular roof <NUM>, as the eight-sided perimeter of an octagonal roof <NUM>).

<FIG> illustrates an isometric view of a frame lid <NUM> and an insert <NUM> as may be used in a photonic platform <NUM> using a one-lid design. In some embodiments, the slot <NUM> is defined with an opening through the wall <NUM> and the foot <NUM> of the frame lid <NUM> so as to allow for the frame lid <NUM> to be placed vertically over the optical fiber <NUM> and onto the adhesive <NUM>, as is discussed in greater detail in regard to <FIG> and <FIG> and <FIG> and <FIG>. In contrast, embodiments defining the slot <NUM> such that the wall <NUM> and/or foot <NUM> define a boundary of the slot <NUM> (e.g., as in <FIG>), may require the optical fiber <NUM> to be connected to the PIC <NUM> after placing the frame lid <NUM> over the optical assembly <NUM> or by sliding the frame lid <NUM> into position along the length of an optical fiber <NUM> attached to the PIC <NUM>, as is discussed in greater detail in regard to <FIG> and <FIG>.

The insert <NUM>, which may be set in place before placing the frame lid <NUM> over the optical fiber <NUM> or after placing the frame lid <NUM> over the optical fiber <NUM>, provides additional support for the optical fiber <NUM> and reduces the cross-sectional area of the slot <NUM> that is to be sealed with a sealant to ensure that the cavity <NUM> is hermetically sealed from the outside environment. The insert <NUM> is adapted to the size and shape of the slot <NUM> and the size, shape, and relative location of the optical fiber <NUM>, and accordingly may be provided in several different sizes, shapes, and orientations in various embodiments. Examples of several inserts <NUM>, and the sub-features thereof, are discussed in greater detail in regard to <FIG>.

<FIG> illustrate a photonic platform <NUM> using a multi-lid design. In various embodiments, a multi-lidded photonic platform <NUM> may be modified from a one-lidded photonic platform <NUM> (as is discussed in relation to <FIG>), for example, when retrofitting, repairing, or inspecting internal components of a one-lidded photonic platform <NUM>. Although illustrated and discussed primarily as a two-lidded design, it is contemplated that more than two secondary (or second) frame lids <NUM> may be included in a multi-lid design with corresponding ports <NUM> through the primary (or first) frame lid <NUM>.

<FIG> illustrate profile views with a portion of a two-lidded photonic platform <NUM> cut away to show details of an optical assembly <NUM> connected thereto. The photonic platform <NUM> includes the components of the optical assembly <NUM> (such as is illustrated in <FIG>), a first frame lid <NUM>, and a second frame lid <NUM>. As in the one-lidded photonic platform <NUM>, the first frame lid <NUM> includes a foot <NUM> that is in contact with the adhesive <NUM> and (when cured) bonded to the substrate <NUM> via the adhesive <NUM>, a roof <NUM> that is in contact with the TIM 160a,b of the EIC 140a,b within a cavity <NUM> defined between the first frame lid <NUM> and the substrate <NUM>, and a wall <NUM> that separates the foot <NUM> from the roof <NUM> and defines a slot <NUM> (not visible in <FIG>) as a through-hole that the optical fiber <NUM> passes into/out of the cavity <NUM>. In various embodiments, the adhesive <NUM> forms a bond between the first frame lid <NUM> and the substrate <NUM> that is airtight or watertight, and a sealant (not illustrated) is placed in the slot <NUM> to form an airtight or watertight seal so that the cavity <NUM> is hermetically sealed from the external environment when cured.

In addition to the first frame lid <NUM>, the two-lidded design includes a second frame lid <NUM> which is inserted into the cavity <NUM> via a through-hole, designated as port <NUM>, defined through the roof <NUM> of the first frame lid <NUM>. The second frame lid <NUM> is bonded to, and thermally isolated from, the first frame lid <NUM> via a thermal isolator <NUM>. The thermal isolator <NUM> is a thermal insulator that impedes the transfer of heat between the first frame lid <NUM> and the second frame lid <NUM>, and when cured, seals the port <NUM>. The second frame lid <NUM> includes a cap <NUM>, which connects with the thermal isolator <NUM> to seal the port <NUM> and to interface with various external devices (e.g., heatsinks <NUM>, as discussed in greater detail in regard to <FIG>), and a plug <NUM>, which extends from the cap <NUM> into the cavity <NUM> to contact the TIM <NUM> of a designated EIC <NUM>. Although illustrated in contact with the third EIC 140c in contact with the PIC <NUM>, in other examples, useful for understanding the invention, the second frame lid <NUM> may be in contact with a different EIC <NUM> (e.g., a thermally sensitive EIC <NUM> or an EIC <NUM> outputting a greater than average amount of heat) within the cavity <NUM> to thermally isolate that EIC <NUM> from the other EICs <NUM>.

Although in some embodiments, such as illustrated in <FIG>, the upper contact surfaces of the TIMs <NUM> (that contact the first frame lid <NUM> or the second frame lid <NUM>) may be disposed in one plane at a shared height relative to the substrate <NUM>, in other embodiments, such as illustrated in <FIG>, the TIMs <NUM> may be located at different heights relative to the substrate <NUM>. Therefore, the plug <NUM> of the second frame lid <NUM> may extend to various lengths from the cap <NUM> in various embodiments to account for EICs <NUM> and TIMs <NUM> of various heights.

In various embodiments, the second frame lid <NUM> may be inserted into the port <NUM> after the first frame lid <NUM> is placed over the optical assembly <NUM>, or may be placed into the port <NUM> before placing the first frame lid <NUM> over the optical assembly <NUM>. Additionally, the thermal isolator <NUM> may be placed on a first side of the roof <NUM> surrounding the port <NUM> (e.g., as in <FIG>) or may be placed within the port <NUM> (e.g., as shown in <FIG>).

<FIG> illustrate isometric views of a two-lidded frame lid assembly. In some embodiments, the slot <NUM> is defined with an opening through the wall <NUM> and the foot <NUM> of the first frame lid <NUM> (e.g., as in <FIG> and <FIG>) so as to allow for the first frame lid <NUM> to be placed vertically over the optical fiber <NUM> and onto the adhesive <NUM>, as is discussed in greater detail in regard to <FIG> and <FIG> and <FIG> and <FIG>. In contrast, embodiments defining the slot <NUM> such that the wall <NUM> and/or foot <NUM> define a boundary of the slot <NUM> (e.g., as in <FIG>), may require the optical fiber <NUM> to be connected to the PIC <NUM> after placing the first frame lid <NUM> over the optical assembly <NUM> or by sliding the first frame lid <NUM> into position along the length of an optical fiber <NUM> attached to the PIC <NUM>, as is discussed in greater detail in regard to <FIG> and <FIG>.

The insert <NUM>, which may be set in place before placing the first frame lid <NUM> over the optical fiber <NUM> or after placing the first frame lid <NUM> over the optical fiber <NUM>, provides additional support for the optical fiber <NUM> and reduces the cross-sectional area of the slot <NUM> that is to be sealed with a sealant to ensure that the cavity <NUM> is hermetically sealed from the outside environment. The insert <NUM> is adapted to the size and shape of the slot <NUM> and the size, shape, and relative location of the optical fiber <NUM>, and accordingly may be provided in several different sizes, shapes, and orientations in various embodiments. Examples of several inserts <NUM>, and the sub-features thereof, are discussed in greater detail in regard to <FIG>.

The thermal isolator <NUM> is sized and shaped according to the size and shape of the port <NUM> and the size and shape of the cap <NUM>. The thermal isolator <NUM> may be placed around the perimeter of the port <NUM> outside of the cavity <NUM> (e.g., as in <FIG>), or may be secured to the perimeter of the port <NUM> both inside and outside of the cavity <NUM> (e.g., as in <FIG>). In various embodiments, the thermal isolator <NUM> may be cured to form an airtight or water tight seal with the cap <NUM> of the second frame lid <NUM>, or may include a sealant or adhesive that forms such a seal with the cap <NUM> when cured. In various embodiments, the thermal isolator <NUM> is bonded to the first frame lid <NUM> before the second frame lid <NUM> is bonded to the thermal isolator <NUM> (e.g., as in <FIG>), or may be bonded to the first frame lid <NUM> and to the second frame lid <NUM> during one curing/fabrication process (e.g., as in <FIG>).

The second frame lid <NUM> is sized and shaped according to the size and shape of the port <NUM>, the relative distance to the TIM <NUM> to which the plug <NUM> is to be placed in thermal contact with, and the size and shape of any external devices to be connected to the second frame lid <NUM>. The cap <NUM> provides an exposed surface (opposite to the side the plug <NUM> extends from) to which various external devices (such as heat sinks <NUM> as in <FIG>) may be mounted and through which heat generated by the EIC <NUM> connected to the plug <NUM> may be dissipated into the environment. Although shown in <FIG> and <FIG> with a generally rectangular shape, the cap <NUM> may be provided in various shapes in various other embodiments. The plug <NUM> may also be provided with various cross-sectioned shapes (e.g., generally rectangular in <FIG> and generally circular in <FIG>), and may extend to various lengths from the cap <NUM> based on the relative height of the TIM <NUM> and EIC <NUM> that the plug <NUM> is to connect with.

<FIG> is an isometric view of an assembled photonic platform <NUM> connected to external heatsinks <NUM>. A first external heatsink 340a is bonded to the first frame lid <NUM>, and a second external heatsink 340b is bonded to the second frame lid <NUM> in <FIG>. Each of the heatsinks <NUM> bonded to different portions of the photonic platform <NUM> may be of the same or of different types, and may include passive radiative heat sinks and active heat sinks (e.g., forced air, forced liquid) of various sizes, materials, and form factors based on the intended operating environments and heat generated when operating the optical assembly <NUM>.

<FIG> illustrates several variations of inserts 240a-f (generally, insert <NUM>), as may be used to fully or partially occupy a slot <NUM> in a frame lid assembly as described herein. Each of the inserts <NUM> include an insert foot <NUM>, and an insert wall <NUM> that are set at a relative angle to each other equal to the relative angle of the foot <NUM> and the wall <NUM> that the insert <NUM> is to be bonded to. The insert <NUM> is inserted into the slot <NUM>, and is bonded to the substrate <NUM> via the adhesive <NUM>, and to the foot <NUM> and the wall <NUM> via a sealant or another adhesive. Once inserted into the slot <NUM>, the insert <NUM> defines an opening of a smaller size than the slot <NUM> that the optical fibers <NUM> pass through. The opening is sealed by various sealants to provide a hermetically sealed cavity <NUM> and to secure the optical fibers <NUM> traversing the opening. In various embodiments, the sealant is cured during the same operation that cures the adhesive <NUM>.

The opening is sized according to the shape, size, and number of the optical fibers <NUM> connected to the PIC <NUM> and may be defined internally to the insert wall <NUM> (e.g., as in inserts 240a and 240b) or may be defined between the insert wall <NUM> and the wall <NUM> of the first frame lid <NUM> (e.g., as in inserts 240c-f). In embodiments using an open cutout <NUM> (e.g., inserts 240c-e) or no cutout <NUM> (e.g., insert 240f), the size and shape of the opening is defined by a remaining open portion of the slot <NUM> between a distal end <NUM> of the insert wall <NUM> and the wall <NUM>, and any portion of the insert wall <NUM> defining a cutout <NUM>. In other embodiments with closed cutouts <NUM> (e.g., inserts 240a and 240b), the size and shape for the opening is defined by the size and shape of the cutout <NUM>.

<FIG> and <FIG> illustrate assembly of a photonic platform with a first frame lid <NUM> and a pre-placed insert <NUM>, according to embodiments of the present disclosure. <FIG> shows a first cutaway view of the photonic platform and <FIG> shows a second planar view of the photonic platform. In <FIG> and <FIG>, the second frame lid <NUM> and thermal isolator <NUM> (and associated arrow <NUM>) are shown as optional elements; the second frame lid <NUM> and thermal isolator <NUM> may be omitted in some examples useful for understanding the invention,
placed before placing the first frame lid <NUM>, or placed after placing the first frame lid <NUM>. When the first frame lid <NUM> defines a slot <NUM> through the wall <NUM> and the foot <NUM>, the fabricator may place the first frame lid <NUM> over the optical assembly <NUM> (per Arrow <NUM>). The insert <NUM> may be pre-positioned so that when the fabricator places the first frame lid <NUM>, the slot <NUM> is placed around and in contact with the insert <NUM>, and the optical fiber <NUM> is captured between the insert <NUM> and the first frame lid <NUM>. After placing the first frame lid <NUM> over the optical assembly <NUM>, in multi-lidded embodiments, the fabricator may then place the thermal isolator <NUM> and/or the second frame lid <NUM> (per Arrow <NUM>).

<FIG> and <FIG> illustrate assembly of a photonic platform with a first frame lid <NUM> and a subsequently-placed insert <NUM>, according to embodiments of the present disclosure. <FIG> shows a first cutaway view of the photonic platform and <FIG> shows a second planar view of the photonic platform. In <FIG> and <FIG>, the second frame lid <NUM> and thermal isolator <NUM> (and associated arrow <NUM>) are shown as optional elements; the second frame lid <NUM> and thermal isolator <NUM> may be omitted in some examples useful for understanding the invention,
placed before placing the first frame lid <NUM>, or placed after placing the first frame lid <NUM>. When the first frame lid <NUM> defines a slot <NUM> through the wall <NUM> and the foot <NUM>, the fabricator may place the first frame lid <NUM> over the optical assembly <NUM>. The fabricator may place the insert <NUM> into the slot <NUM> of the pre-positioned first frame lid <NUM> so that the insert <NUM> is placed "under" the optical fiber <NUM> and the first frame lid <NUM> and in contact with the adhesive <NUM> (per Arrow <NUM>). The insert <NUM> and first frame lid <NUM> thus capture the optical fiber <NUM> between the insert <NUM> and the first frame lid <NUM>. After placing the insert <NUM> into the slot <NUM>, in multi-lidded embodiments, the fabricator may then place the thermal isolator <NUM> and/or the second frame lid <NUM> (per Arrow <NUM>).

<FIG> and <FIG> illustrate assembly of a photonic platform with a first frame lid <NUM> defining a closed slot <NUM>, according to embodiments of the present disclosure. In embodiments using a closed slot <NUM>, the fabricator inserts the optical fiber <NUM> through the slot <NUM>, and slides the first frame lid <NUM> into position along the length of the optical fiber (per Arrow <NUM>). Once in position over the optical assembly <NUM>, the fabricator lowers the first frame lid <NUM> to place the foot <NUM> in contact with the adhesive <NUM> (per Arrow <NUM>). In multi-lidded embodiments, the fabricator may then place the thermal isolator <NUM> and/or the second frame lid <NUM> (per Arrow <NUM>). In <FIG> and <FIG>, the second frame lid <NUM> and thermal isolator <NUM> (and associated arrow <NUM>) are shown as optional elements; the second frame lid <NUM> and thermal isolator <NUM> may be omitted in some examples useful for understanding the invention, placed before placing the first frame lid <NUM>, or placed after placing the first frame lid <NUM>.

<FIG> is a flowchart of a method <NUM> for attaching a frame assembly to an optical assembly <NUM>. The optical assembly <NUM>, such as the optical assembly discussed in relation to <FIG> includes a substrate <NUM>, a first EIC 140a mounted to the substrate <NUM> (either directly or via an interposer <NUM>), a PIC <NUM> mounted to the substrate <NUM> (directly or via an interposer <NUM>) on a first side and to a second EIC 140b on an opposite side, and an optical fiber <NUM>, connected to the PIC <NUM>.

Method <NUM> begins at block <NUM>, where a fabricator applies an adhesive <NUM> to the substrate <NUM> in a perimeter around the optical assembly <NUM>. The adhesive <NUM> provides a thermally activated bond between the substrate <NUM> and the frame assembly that is airtight or watertight to hermetically seal the optical assembly <NUM> within the frame assembly.

At block <NUM>, the fabricator applies a first TIM 160a to a first surface of the first EIC 140a, and a second TIM 160b to a second surface of the second EIC 140b. The TIM <NUM> are flowable materials that provide a thermally conductive surface between the EIC <NUM> of the optical assembly <NUM> and the frame lid assembly.

At block <NUM>, the fabricator places a first frame lid <NUM> onto the optical assembly <NUM>. Once placed, in one embodiment, a foot <NUM> of the first frame lid <NUM> contacts the adhesive <NUM>, a roof <NUM> of the first frame lid <NUM> contacts the first TIM 160a, and the optical fiber <NUM> is disposed a slot <NUM> defined in a wall <NUM> of the first frame lid <NUM> that is nonparallel to the roof <NUM>. In examples, useful for understanding the invention, using a one-lidded design, the roof <NUM> is also in contact with the second TIM 160b, but in embodiments using a two-lidded design, the fabricator leaves the second TIM 160b exposed by a port <NUM> defined in the roof <NUM>.

In embodiments in which the first frame lid <NUM> defines an open slot <NUM> through the foot <NUM> and the wall <NUM>, the fabricator may vertically place the first frame lid <NUM> onto the adhesive <NUM> and over the optical assembly <NUM> (e.g., by lowering the first frame lid <NUM> into position). When using an insert <NUM>, the fabricator places the insert <NUM> into the slot <NUM> in contact with the adhesive <NUM> and between the substrate <NUM> and the optical fiber <NUM>. The insert <NUM> may be placed in the slot <NUM> and "under" the optical fiber <NUM> so that when the first frame lid <NUM> is placed onto the adhesive <NUM> and "over" the optical fiber <NUM>, the optical fiber <NUM> is captured between the first frame lid <NUM> and the insert <NUM>. The fabricator may put the insert <NUM> in place before or after placing the first frame lid <NUM>.

In embodiments in which the first frame lid <NUM> defines a closed slot <NUM> through the wall <NUM>, the fabricator inserts a distal end of the optical fiber <NUM> from the PIC <NUM> through the slot <NUM> and slides the first frame lid <NUM> along a length of the optical fiber <NUM> until the foot <NUM> is in contact with the adhesive <NUM>. The fabricator may then adjust the position of the first frame lid <NUM>.

At block <NUM>, when using a multi-lidded design, the fabricator places a second frame lid <NUM> through the port <NUM> to contact the second TIM 160b. The second frame lid <NUM> is thermally isolated from the first frame lid by a thermal isolator <NUM>. Method <NUM> may omit block <NUM> when using a one-lidded design in examples, useful for understanding the invention. In some embodiments, the fabricator applies a thermal isolator <NUM> to the port <NUM>, either around the perimeter of the port <NUM> outside of the cavity <NUM> or surrounding the lip of the roof <NUM> that defines the port <NUM> both inside and outside of the cavity <NUM>. The thermal isolator <NUM> separates the second frame lid <NUM> from the first frame lid <NUM>, and the fabricator may apply the thermal isolator <NUM> to roof <NUM> before placing the first frame lid <NUM> onto the optical assembly <NUM> or after placing the first frame lid <NUM> onto the optical assembly <NUM>.

At block <NUM>, the fabricator applies additional sealants or adhesives to the photonic platform at any designated joints. For example, the fabricator may apply sealants to joints between the foot <NUM> and wall <NUM> of the first frame lid <NUM> and any inserts <NUM> placed in slots <NUM> defined therein, and to the openings around the optical fibers <NUM> passing through the first frame lid <NUM>, to the port <NUM> in which a second frame lid <NUM> is inserted (including to the thermal isolator <NUM>).

At block <NUM>, the fabricator cures the photonic platform at a designated temperature and pressure to hermetically seal the cavity <NUM> defined between the first frame lid <NUM> and the substrate <NUM>. For example, a fabricator may cure the photonic platform at a temperature selected to be high enough to flow the TIM <NUM> and activate the adhesive <NUM> and any sealants, but low enough to not permanently affect the operational characteristics of the EIC <NUM> or PIC <NUM>. The fabricator may select a pressure (e.g., low or medium vacuum) to evacuate air from the cavity <NUM>, so that when the photonic platform is hermetically sealed, the cavity <NUM> maintains a low-pressure environment to reduce convective heat transfer between elements within the cavity <NUM>. The fabricator cures the adhesive <NUM>, the first TIM 160a, and the second TIM 160b to bond the first frame lid <NUM> onto the optical assembly <NUM>. The fabricator also cures any applied sealant to seal the optical fiber <NUM> in the slot <NUM>, secure the insert <NUM> (if included) in the slot <NUM>, secure the thermal isolator <NUM> and the second frame lid <NUM> (if included) to the first frame lid <NUM>, and seal the port <NUM> (if included).

At block <NUM>, the fabricator places external devices on the lid(s) of the photonic platform. For example, the fabricator may place a first heatsink 340a on the first frame lid <NUM> and/or a second heatsink 340b on the second frame lid <NUM>. In some embodiments, block <NUM> is performed before block <NUM> so that the external devices are bonded to the photonic platform during the curing process. In some embodiments, block <NUM> is performed after block <NUM>, and the external devices may be secured to the photonic platform in a separate curing process or by mechanical clips that do not require a curing process. In other embodiments, the fabricator may omit block <NUM> if no external devices are to be bonded to the photonic platform. Method <NUM> may then conclude.

In the current disclosure, reference is made to various examples. However, the scope of the present disclosure is not limited to specific described examples. Instead, any combination of the described features and elements, whether related to different examples or not, is contemplated to implement and practice contemplated examples. Additionally, when elements of the examples are described in the form of "at least one of A and B," it will be understood that examples including element A exclusively, including element B exclusively, and including element A and B are each contemplated. Furthermore, although some examples disclosed herein may achieve advantages over other possible solutions or over the prior art, whether or not a particular advantage is achieved by a given example is not limiting of the scope of the present disclosure. Thus, the features, examples, and advantages disclosed herein are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to "the invention" shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s). As will be appreciated by one skilled in the art, the examples disclosed herein may be exemplified as a system, method or computer program product. Accordingly, examples may take the form of an entirely hardware example, an entirely software example (including firmware, resident software, micro-code, etc.) or an example combining software and hardware aspects that may all generally be referred to herein as a "circuit," "module" or "system. " Furthermore, examples may take the form of a computer program product exemplified in one or more computer readable medium(s) having computer readable program code embodied thereon.

Examples of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatuses (systems), and computer program products according to examples presented in this disclosure.

The flowchart illustrations and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various examples.

Claim 1:
A platform (<NUM>), comprising:
a substrate (<NUM>);
a first Integrated Circuit, IC, mounted to the substrate (<NUM>);
a photonic integrated circuit (<NUM>) mounted to the substrate (<NUM>);
a second IC (140c) mounted to the photonic integrated circuit (<NUM>), the photonic integrated circuit being mounted between the second IC and the substrate (<NUM>);
a first frame lid (<NUM>) mounted to the substrate (<NUM>) and defining a cavity (<NUM>) with the substrate (<NUM>) that encapsulates the first IC, the photonic integrated circuit (<NUM>), and the second IC (140c), the first frame lid (<NUM>) comprising:
a first roof (<NUM>) disposed in a first plane parallel to the substrate (<NUM>),
the first roof (<NUM>) defining a port providing access to the second IC (140c) through the first roof (<NUM>);
a foot (<NUM>) disposed in a second plane parallel to the first plane and connected to the substrate (<NUM>);
a wall (<NUM>), connecting the first roof (<NUM>) to the foot (<NUM>); and
an opening (<NUM>) in the wall arranged to allow an optical fiber to pass through the wall (<NUM>) to connect to the photonic integrated circuit (<NUM>);
the platform (<NUM>) further comprising a second frame lid (<NUM>) mounted to the first roof (<NUM>) via a thermal isolator (<NUM>) and extending through the port to be in thermal contact with the second IC (140c).