Patent Description:
Bandwidth increases in computing platforms has resulted in a switch from electrical signals to optical signals. In an optical platform, a compute die is communicatively coupled to a plurality of optics dies. The optics dies are configured to convert signals between electrical and optical regimes. In some instances optical connectors are attached to the optics dies. The optical connectors house optical fibers over which the optical signals are propagated. The ends of the optical fibers are exposed and fit into V-grooves on the optics die.

The use of optical connectors is not without issue. One issue is that optical connectors result in incomplete encapsulation of the system. This may provide reliability concerns. For example, incomplete encapsulation will allow moisture to enter the package, and ice can form when temperatures go below <NUM>. When the ice melts, short circuits may occur. Another issue is that existing optical connectors may not be compatible with high volume manufacturing (HVM). Exposed optical fibers are vulnerable to mechanical shock during handling and thermal shock during solder reflow. Additionally, the tool for mounting the optical connector may require several pick-up tool tips in order to provide the mounting.

Yet another drawback of existing optical systems is the uncontrolled flow of underfill and encapsulation materials. For example, the multi-chip packages require controlled underfills. Additionally, encapsulation materials also need precise control in order not to spread beyond desired areas. Currently, location and uniformity of material with a certain viscosity is hard to control by just dispensing it on planar surfaces.

Yet another drawback of existing optical systems is the need for a large external fiber shuffler for routing the optical fibers. The large footprint of fiber shufflers occupy a large area on the package substrate and/or the board. As such, valuable real estate is lost to optical routing. <CIT> discloses an "Optically enabled Cavity-Down BGA IC Package". The package comprises an interposer board to route signals between a microchip and the external world, a heat-spreader plate, a microchip, wirebonds, encapsulation epoxy, and solder balls. The microchip is fixed using electrically/thermally conductive epoxy in order to electrically access an optical port. A typical step in the assembly of this type of IC package is to next make a small dam of epoxy around the inner cavity and fill the entire cavity with epoxy to completely cover the microchip and wirebonds which results in a slightly raised, hard, flat surface of epoxy in the middle of the package.

Described herein are multi chip optical packages, in accordance with various embodiments. In the following description, various aspects of the illustrative implementations will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that the present invention may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the illustrative implementations. However, it will be apparent to one skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative implementations.

Various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the present invention, however, the order of description should not be construed to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation.

As noted above, multi-chip optical packages suffer from various integration issues. Accordingly, embodiments disclosed herein include various architectures for improving the reliability and ease of assembly, as well as providing a decreased footprint. For example, reliability may be improved by sealing the optical connectors. Ease of assembly may be improved by providing micro channels and/or by embedding the optical fibers. The footprint may be decreased by providing a shuffler with a reduced footprint.

Particularly, in some embodiments, the optical connectors are fully encapsulated. The full encapsulation may prevent reliability concerns, such as water in the package resulting in short circuits. The full encapsulation is made by providing a lid over the optical interconnects. The lid may cover a recessed portion of the package substrate. The lid may be clipped or adhered to the integrated heat spreader (IHS) with an adhesive or by magnets. The lid may be further improved by providing a sealant. The sealant fills the cavity and surrounds the ferrules to provide a complete seal at the edge of the optical package.

In some embodiments, ease of assembly is increased by providing micro channels in various surfaces. The micro channels can be used to direct and/or restrict flow of dispensed materials, such as epoxies, underfills, and sealants. For example, the micro channels may be provided on package substrates, the IHS, or the V-grooves on the optics die. Various micro channel designs can be used to promote the flow of the dispensed fluid in a certain direction and/or restrict flow of the dispensed fluid.

In some embodiments, ease of assembly and reliability is further improved by providing the fibers in a molded housing. Particularly, the ferrule, a fiber distribution housing, and a fiber holder are molded into a single component. Molding into a single component allows for a single tip in a pick-and-place tool to be used to insert the fibers into the V-grooves on the optics die. Additionally, the molding protects the fibers from thermal and mechanical shock.

In some embodiments, the footprint of the optical system is reduced by utilizing an improved fiber shuffler. In a fiber shuffler design, the optical fibers are coupled to grating couplers on the optics die. The optical fibers are bent by a fiber array unit (FAU) and fed into a fiber shuffler that has V-grooves with different depths. After exiting the fiber shuffler, a ferrule aligns the fibers into a plurality of columns. As such, a single row at a first end of optical fibers can be rerouted to form a plurality of columns at a second end of the optical fibers.

Referring now to <FIG>, a plan view illustration of an optical package <NUM> is shown, in accordance with an embodiment. In an embodiment, the optical package <NUM> is shown from below with the package substrate being transparent for clarity. As shown, the optical package <NUM> comprises a compute die <NUM> and a plurality of optics dies <NUM>. The compute die <NUM> may be any die, such as a processor, a graphics processor, or the like. In an embodiment, the optics dies <NUM> provide functionality for converting between optical and electrical signals. The optics dies <NUM> may be communicatively coupled to the compute die <NUM> by a bridge or other interconnect on the package substrate (not shown).

In an embodiment, optical connectors <NUM> may be coupled to the optics dies <NUM>. The optical connectors <NUM> may comprise a plurality of fibers <NUM> and a ferrule <NUM>. For example, the plurality of fibers <NUM> may comprise twenty four fibers in some embodiments. The fibers <NUM> may be secured into V-grooves on the optics dies <NUM>.

As shown in <FIG>, an integrated heat spreader (IHS) <NUM> is provided over top surfaces of the compute die <NUM> and the optics dies <NUM>. That is, in the view of <FIG>, the IHS <NUM> is below the compute die <NUM> and the optics die <NUM>. In an embodiment, the IHS <NUM> also covers portions of the optical connectors <NUM>. In an embodiment, the ferrules <NUM> may extend out past an edge of the IHS <NUM>.

Referring now to <FIG>, a plan view illustration of the bottom of the optical package <NUM> showing the package substrate <NUM> is shown, in accordance with an embodiment. In an embodiment, the package substrate <NUM> may have an H-shaped footprint. That is, recesses <NUM> may be provided along opposite edges of the package substrate <NUM>. In an embodiment, the optical connectors <NUM> are provided in the recesses <NUM>. As shown in <FIG>, the recesses <NUM> are covered by a lid <NUM>. The lid <NUM> provides a seal around the bottom of the optical connectors <NUM>.

The lid <NUM> may comprise any number of architectures. For example, the lid <NUM> may be a clip on component. In other embodiments, the lid <NUM> may be secured to the IHS <NUM> by an adhesive or by magnets.

Examples of various lid <NUM> architectures that include clip on architectures are shown in <FIG>. As shown in <FIG>, the optical package <NUM> comprises a package substrate <NUM> and an IHS <NUM>. Solder balls <NUM> or other interconnects may be provided on the package substrate <NUM>. In an embodiment, the lid <NUM> comprises a plate <NUM> and clips <NUM>. The plate <NUM> seals an opening (i.e., the recess) in the package substrate <NUM>. The clips <NUM> may secure the plate <NUM> to the package substrate <NUM>. In an embodiment, the plate <NUM> and the clips <NUM> may comprise a plastic material or they may comprise metallic materials. In the illustrated embodiment, the plate <NUM> sits above a surface of the package substrate <NUM>.

Referring now to <FIG>, a cross-sectional illustration of the optical package <NUM> with an alternative lid <NUM> architecture is shown, in accordance with an embodiment. As shown, the plate <NUM> may be substantially coplanar with a surface of the package substrate <NUM>.

Referring now to <FIG>, a cross-sectional illustration of the optical package with yet another lid <NUM> architecture is shown, in accordance with an embodiment. In an embodiment, the lid <NUM> may comprise spring ends <NUM> on opposite ends of the plate <NUM>. The spring ends <NUM> may bend inward to pass through the opening and expand out after passing the opening to secure the lid <NUM>. In an embodiment, the plate <NUM> and the spring end <NUM> may comprise a thin metal sheet, though other materials may also be used in accordance with additional embodiments.

Referring now to <FIG>, a cross-sectional illustrations of an optical package <NUM> is shown, in accordance with an additional embodiment. In an embodiment, the optical package <NUM> comprises a package substrate <NUM> and an IHS <NUM>. Ferrules <NUM> are provided on the IHS <NUM>. In an embodiment, a lid <NUM> provides a seal around the ferrules <NUM>. The lid <NUM> may comprise a plate <NUM> with support posts <NUM>. The support posts <NUM> may extend down to the IHS <NUM> between the ferrules <NUM>. In an embodiment, the support posts <NUM> are secured to the IHS <NUM> by an adhesive <NUM>.

Referring now to <FIG>, a perspective view illustration of an optical package <NUM> is shown, in accordance with an embodiment. In an embodiment, the optical package <NUM> comprises a package substrate <NUM> with a recess <NUM>. The IHS <NUM> is shown below the recess <NUM>. Edges of the optics dies <NUM> are also illustrated in <FIG>. The optical connectors <NUM> are shown removed from the recess <NUM> in order to more clearly illustrate the layout on the IHS <NUM>. As shown, a plurality of magnets <NUM> and <NUM> may be provided on the IHS <NUM>. The magnets <NUM> and <NUM> may be positioned to interface with support posts of the lid (not shown in <FIG>). While magnets <NUM> and <NUM> are shown in <FIG>, it is to be appreciated that the magnets may alternatively be formed only on the lid in cases where the IHS <NUM> is a magnetic or metallic material.

Referring now to <FIG>, a perspective view illustration of the lid <NUM> is shown, in accordance with an embodiment. As shown, the lid <NUM> comprises a plate <NUM> and support posts <NUM>. Magnets <NUM> may also be provided along edges of the plate <NUM>. The magnets <NUM> may align with the positioning of magnets <NUM> shown in <FIG>. Additionally, magnets may also be included on the support posts <NUM> in some embodiments.

It is to be appreciated that the lids described above provide a seal of the bottom surface of the recess in the package substrate. However, the edge surface between the lid and the IHS where the ferrules exit the cavity may not be sealed in some embodiments. In additional embodiments, a sealant may also be included in order to provide a seal around the ferrules. Examples of such embodiments are provided in <FIG>.

Referring now to <FIG>, an edge view of the recess in an optical package <NUM> is shown, in accordance with an embodiment. As shown, the ferrules <NUM> are set on the IHS <NUM>. A sealant <NUM> may be disposed around the ferrules <NUM>. The sealant <NUM> may be a high viscosity sealant. For example, the sealant <NUM> may be an epoxy or the like. In an embodiment, a plate <NUM> of a lid is brought down into contact with the sealant <NUM>, as indicated by the arrow. In an embodiment, the plate <NUM> may be part of any of the lids such as those described above. For example, the plate <NUM> may be clipped or otherwise adhered to the IHS (e.g., with adhesive or magnets). As shown in <FIG>, the edge of the optical package <NUM> is completely sealed with the plate <NUM>, the sealant <NUM>, and the ferrules <NUM> completely filling the edge of the recess. In addition to providing a seal for the recess, the sealant <NUM> may also prevent the ferrules from moving when mechanical and/or thermal shock is applied to the optical package <NUM>.

Referring now to <FIG>, an edge view of the recess in an optical package <NUM> is shown, in accordance with an embodiment. In an embodiment, the plate <NUM> may further comprise supports <NUM>. In an embodiment, the supports <NUM> may be attached to the plate <NUM>, or the supports <NUM> may be a monolithic part of the plate <NUM>. The supports <NUM> are configured to be placed between the ferrules <NUM> on the IHS <NUM>. The supports <NUM> provide additional volume that may make it easier for the sealant <NUM> to provide a proper seal of the recess.

As shown by the arrow in <FIG>, the plate <NUM> and supports <NUM> are inserted down towards the IHS <NUM> to provide a device similar to the optical package <NUM> shown in <FIG>. In <FIG>, the spacings between the ferrules <NUM> are filled by a combination of the supports <NUM> and the sealant <NUM>. As such, a smaller volume of sealant <NUM> is necessary to fill the edge of the recess.

Referring now to <FIG>, a series of edge view illustrations depicting a process for sealing a recess in an optical package <NUM> is shown, in accordance with an additional embodiment. As shown in <FIG>, a plurality of supports <NUM> are provided between the ferrules <NUM> over the IHS <NUM>. That is, instead of connecting the supports <NUM> to the plate <NUM> (as shown in <FIG>), the supports <NUM> are attached to the IHS <NUM>. In an embodiment, the supports <NUM> may be adhered to the IHS <NUM>, or the supports <NUM> may be a monolithic part of the IHS <NUM>. As indicated by the arrows, the sealant <NUM> and the plate <NUM> are then added to provide a structure similar to that shown in <FIG>. Similar to <FIG>, the spacings between the ferrules <NUM> are filled by a combination of the supports <NUM> and the sealant <NUM>. As such, a smaller volume of sealant <NUM> is necessary to fill the edge of the recess.

The use of a lid and a sealant such as described above allows for the recess into the package substrate to be fully sealed. The IHS may form one surface of a cavity and the package substrate provides portions of the sidewalls of the cavity. In an embodiment, the lid can provide the surface of the cavity opposite from the IHS, and the sealant can provide the missing sidewall of the cavity. As such, the cavity can be fully sealed to prevent moisture from entering the optical package. In some embodiments, the sealant may also substantially fill the cavity.

Embodiments disclosed herein may also provide for improved manufacturability and reliability. An example of an optical connector <NUM> is shown in <FIG>. The optical connector <NUM> comprises a socket <NUM> (also sometimes referred to as a plug). A ferrule <NUM> is inserted into the socket <NUM>, and a holder <NUM> is spaced away from the ferrule <NUM>. The holder <NUM> maintains fibers <NUM> at the proper alignment for insertion into V-grooves on an optics die. The fibers <NUM> may be arranged in a 2X12 alignment in the ferrule <NUM> and a 1X24 alignment in the holder <NUM>. Between the holder <NUM> and the ferrule <NUM> the fibers are bent to accommodate the different alignments on each end.

However, such an architecture provides several drawbacks. One drawback is that insertion of the fibers <NUM> into V-grooves requires complex pick-and-place tools. Particularly, the pick-and-place tool requires at least three different tips. A first tip is needed to control the socket <NUM> and ferrule <NUM>, a second tip is needed to control the holder <NUM>, and a third tip is needed to hold a fiber lid to press the ends of the fibers <NUM> into the V-grooves. Additionally, the portions of the fibers <NUM> between the ferrule <NUM> and the holder <NUM> are exposed to thermal and mechanical shock. As such, the optical connector <NUM> is susceptible to environmental damage during and after installation. Accordingly, embodiments disclosed herein provide an enhanced optical connector <NUM> that mitigates the drawbacks of the optical connector <NUM> illustrated in <FIG>. Such an optical connector <NUM> is illustrated in <FIG>.

Referring now to <FIG>, a perspective view illustration of an optical connector <NUM> is shown, in accordance with an embodiment. In an embodiment, the optical connector <NUM> comprises a socket <NUM>. The socket <NUM> may be substantially similar to the socket <NUM> illustrated in <FIG>. That is, the socket <NUM> may be configured to receive a ferrule <NUM>. In an embodiment, the ferrule <NUM> receives the optical fibers <NUM> and holds them in a 2X24 arrangement. Though, it is to be appreciated that different optical fiber <NUM> arrangements can be used, depending on the number of optical fibers <NUM> in the connector <NUM>.

In an embodiment, the optical connector <NUM> may also comprise a holder <NUM> that is similar to the holder <NUM> in <FIG>. The holder <NUM> may secure the optical fibers <NUM> in an arrangement that is different than the arrangement of the optical fibers in the ferrule <NUM>. In an embodiment, the holder <NUM> arranges the optical fibers <NUM> in a single row. For example, in the case of a twenty four optical fiber <NUM> optical connector <NUM>, the optical fibers <NUM> may be positioned in a 1X24 arrangement.

The optical connector <NUM> in <FIG> differs from the optical connector <NUM> in <FIG> in that a fiber distribution housing <NUM> is provided between the ferrule <NUM> and the holder <NUM>. In an embodiment, the fiber distribution housing <NUM> may be the same material as one or both of the ferrule <NUM> and the holder <NUM>. For example, the fiber distribution housing <NUM>, the ferrule <NUM>, and the holder <NUM> may each comprise glass. In such embodiments, the fiber distribution housing <NUM>, the ferrule <NUM>, and the holder <NUM> may be a monolithic part. That is, in some embodiments, there may be no discernable seam or other boundary between the fiber distribution housing <NUM>, the ferrule <NUM>, and the holder <NUM>. However, in other embodiments, seams may be present between two or more of the fiber distribution housing <NUM>, the ferrule <NUM>, and the holder <NUM>, even when formed from the same material. In yet another embodiment, two or more of the fiber distribution housing <NUM>, the ferrule <NUM>, and the holder <NUM> may be formed with different materials.

The fiber distribution housing <NUM> provides an enclosure around the optical fibers <NUM> as they are bent to allow conversion from one arrangement at the ferrule <NUM> to a second arrangement at the holder <NUM>. For example, the optical fibers <NUM> may be bent so that at the ferrule <NUM> the optical fibers <NUM> are arranged in two or more rows (e.g., a 2X12 array) and at the holder <NUM> the optical fibers <NUM> are arranged in a single row (e.g., a 1X24 array).

In an embodiment, the fiber distribution housing <NUM> entirely surrounds the optical fibers <NUM>. As such, the optical fibers <NUM> are less susceptible to thermal or mechanical shock. Additionally, the fiber distribution housing <NUM> mechanically couples the ferrule <NUM> to the holder <NUM>. As such, a tip for the pick-and-place tool for mounting the optical connector <NUM> to the V-grooves on the optics die may be omitted.

Referring now to <FIG>, a perspective view illustration of the assembly of an optical package <NUM> is shown, in accordance with an embodiment. As shown, the optical package <NUM> may comprise a package substrate <NUM> and an integrated heat spreader <NUM>. A recess in the package substrate <NUM> may result in the exposure of an edge of one or more optics dies <NUM> that are attached to the package substrate <NUM>. The optics dies <NUM> may comprise V-grooves for receiving optical fibers <NUM> of the optical connector <NUM>.

As shown, the optical connector <NUM> may be substantially similar to the optical connector <NUM> in <FIG>. For example, the optical connector <NUM> comprises a socket <NUM>, a ferrule <NUM>, a fiber distribution housing <NUM>, a holder <NUM>, and optical fibers <NUM>. The optical connector <NUM> may be handled by a pick-and-place tool <NUM>. The pick-and-place tool <NUM> may comprise a first tip <NUM>A and a second tip <NUM>B. The first tip <NUM>A may hold the socket <NUM>. The fiber distribution housing <NUM> mechanically couples the holder <NUM> to the ferrule <NUM> that is held by the socket <NUM>. As such, only a single first tip <NUM>A is needed to handle these components of the optical connector <NUM>. In contrast, the optical connector <NUM> in <FIG> requires an additional tip in order to properly align the holder <NUM> since it is not mechanically coupled to the ferrule <NUM>. In an embodiment, the second tip <NUM>B may be arranged to handle the bare ends of the optical fibers <NUM>. The second tip <NUM>B is therefore responsible for holding a fiber lid to press in the bare ends of the optical fibers <NUM> into the V-grooves on the optics dies <NUM>.

The embodiments described above may include the fluidic dispensing of one or more materials in order to allow for proper coupling of components and/or sealing of cavities. For example, the compute die and the optics dies typically include underfill materials, an epoxy may be needed to secure the bare optical fibers to the V-grooves, and sealant may be dispensed to fully seal the cavity formed by the package substrate recess. It is to be appreciated that the control of the various flows of one or more of such fluids is critical in order to provide high yielding and robust optics packages. Accordingly, embodiments disclosed herein include various micro channels into surfaces where such fluids are dispensed in order to control the spread of the materials.

Referring now to <FIG>, a cross-sectional illustration of a fluid <NUM> dispensed on a surface <NUM> is shown, in accordance with an embodiment. With the inclusion of no micro channels or other features, the fluid <NUM> is distributed as viscosity and surface tensions dictate. For example, the fluid <NUM> may have a cross-section that follows a normal distribution.

Referring now to <FIG>, a cross-sectional illustration of a fluid <NUM> dispensed on a surface <NUM> with a micro patterned channel <NUM> is shown, in accordance with an embodiment. As shown, the channel <NUM> interrupts the natural flow of the fluid and truncates a tail of the fluid. Such a channel <NUM> can therefore be used to halt the flow of a fluid across a surface. In the illustrated embodiment, a single channel <NUM> is shown, but it is to be appreciated that multiple channels <NUM> may be provided next to each other to further enhance control of the fluid across the channels.

In contrast, <FIG> is an illustration of channels <NUM> that are formed into a surface that coincide with the primary flow direction of a fluid <NUM> (as indicated by the arrow). As shown, the guiding channels <NUM> promote flow of the fluid <NUM> along the path dictated by the channels <NUM>. In the illustrated embodiment a pair of parallel channels <NUM> are shown. However, it is to be appreciated that a single guiding channel <NUM> or a plurality of guiding channels may be provided to modify the flow of the fluid <NUM>.

In <FIG>, the channels <NUM> and <NUM> are shown as being substantially straight lines. However, it is to be appreciated that the channels may not be linear in some embodiments. For example, in <FIG> an illustration of a circular channel <NUM> is shown, in accordance with an embodiment. The use of a circular channel <NUM> may be used to confine a fluid <NUM> to a given area. In an embodiment, a single circular channel <NUM> may be sufficient to confine a fluid <NUM>. However, in other embodiments, two or more circular channels (e.g., a first circular channel <NUM>A and a second circular channel <NUM>B) may be used to confine the flow of a fluid <NUM>. Additionally, while shown as being circular channels <NUM>, it is to be appreciated that any shaped closed loop channel may be used in other embodiments.

Referring now to <FIG>, a plan view illustration of a fluid distribution structure is shown, in accordance with an embodiment. As shown, the fluid may be dispensed into a main reservoir <NUM> and a plurality of branches <NUM>, <NUM>, <NUM> may intersect the main reservoir <NUM>. The various branches <NUM>, <NUM>, <NUM> have different widths W<NUM>, W<NUM>, and W<NUM>, respectively. Depending on the width W, different amounts of capillary force will draw the fluid to different distances away from the reservoir <NUM>. For example, the first width W<NUM> is the smallest and results in the greatest distance of fluid transfer, and the third width W<NUM> is the largest and results in the shortest distance of fluid transfer.

In <FIG>, the various channels are referred to as being "micro channels". A micro channel may refer to features (e.g., width and/or depth) of the channel being at the micron scale. For example, the width and/or depth of the micro channels may be approximately <NUM> or less, approximately <NUM> or less, or approximately <NUM> or less, depending on the fluid that is being dispensed. Additionally, it is to be appreciated that lengths of the micro channels may be several millimeters or longer. That is the length of the micro channels may not be considered as being on the micron scale in some embodiments.

Referring now to <FIG>, a perspective view illustration of a V-groove <NUM> is shown, in accordance with an embodiment. A first end of the V-groove <NUM> may comprise a spot size converter (SCC) <NUM>. The opposite end of the V-groove <NUM> may be at the end of the optics die (not shown). In an embodiment, a plurality of parallel channels <NUM>A extend along a length direction of the V-groove <NUM>. In an embodiment, the channels <NUM>A may be provided on one or more surfaces of the V-groove <NUM>. For example, the channels <NUM>A may be provided on sidewall surfaces and/or the bottom surface of the V-groove <NUM>. The channels <NUM>A allow for optical epoxy to evenly distribute under a fiber (not shown) and flow under the SSC <NUM>. In an embodiment, second channels <NUM>B may be provided at the end of the V-groove <NUM> opposite from the SSC <NUM>. The second channels <NUM>B may be substantially orthogonal to the channels <NUM>A. Such a configuration prevents overflow of epoxy outside of the V-groove <NUM> and forces more fluid flow towards the SSC <NUM>.

Referring now to <FIG>, a perspective view illustration of an optical package <NUM> is shown, in accordance with an embodiment. As shown, the optical package <NUM> comprises an IHS <NUM> and a package substrate <NUM>. Portions of the optics dies <NUM> are exposed by a recess in the package substrate <NUM>. The optical connectors <NUM> are removed from the recess to more clearly illustrate exposed surfaces of the IHS <NUM>. However, it is to be appreciated that the optical connectors <NUM> are attached to the IHS <NUM> by a mechanical epoxy. It is desirable for this epoxy to not overflow outside of the package and to be evenly distributed. As such, the surfaces of the IHS <NUM> exposed by the recess in the package substrate <NUM> may comprise micro channels to control the flow of the epoxy.

Referring now to <FIG>, an illustration of the IHS <NUM> in isolation from the remainder of the optical package <NUM> is shown, in accordance with an embodiment. As shown, the IHS <NUM> may comprise a first set of parallel channels <NUM>A. The first set of parallel channels <NUM>A are used to evenly distribute the epoxy in the recess region. One or more second channels <NUM>B may be provided along an edge of the IHS <NUM>. The second channels <NUM>B may be substantially perpendicular to the first set of parallel channels <NUM>A. The second channels <NUM>B prevent the flow of the epoxy off the edge of the IHS <NUM>.

Referring now to <FIG>, an illustration of the package substrate <NUM> with a compute die <NUM> and optics dies <NUM> is shown, in accordance with an embodiment. In an embodiment, keep out zones surrounding the optics dies <NUM> and the compute die <NUM> may be provided. The keep out zones are areas of the package substrate <NUM> that should remain free of underfill material. According to the claimed invention, channels <NUM> are provided between the keep out zones. The channels <NUM> are fluidically coupled to reservoirs <NUM>. As such, excess underfill material flows into the channels <NUM> and is transported to the reservoirs <NUM> through capillary action. Therefore, precise control of the underfill in order to maintain proper keep out zones is provided.

In the embodiments described above, the optical connector is described as interfacing with the optics die through V-grooves. However, it is to be appreciated that in other embodiments, the optical connector may be optically coupled to the optics die from above. In such an embodiment, a grating coupler may be provided on the optics die to receive optical signals from a fiber coming down towards the optics die from above. In some instances that fibers are routed to a ferrule using a fiber shuffler or a loom. However, such architectures occupy a large area on the footprint of the printed circuit board (PCB) and are therefore not desirable.

Accordingly, embodiments disclosed herein include an optical coupler that has a reduced footprint. In an embodiment, the optical coupler may be supported by pillars that are on the package substrate or the PCB. The pillars are smaller than previous solutions, and therefore save valuable package or board real estate.

Referring now to <FIG>, a perspective view illustration of a portion of an optics package <NUM> is shown, in accordance with an embodiment. In an embodiment, the optics package <NUM> comprises a package substrate <NUM> and an optics die <NUM> over the package substrate <NUM>. A grating coupler <NUM> may be provided on the optics die <NUM> to receive optical signals. The optics package <NUM> may further comprise an IHS <NUM> over the optics die <NUM>. The IHS <NUM> may comprise an opening to allow for optical signals to pass through the IHS <NUM>.

In an embodiment, the optical coupler comprises a fiber array unit (FAU) <NUM>. The FAU <NUM> bends the optical fibers <NUM>. For example, the bend provided by the FAU <NUM> may be approximately <NUM>°. After exiting the FAU <NUM>, the fibers <NUM> pass through a fiber shuffler <NUM>. The fiber shuffler <NUM> redistributes the fibers <NUM> to different Z-heights. For example, fiber <NUM>A is at a first Z-height, fiber <NUM>B is at a second Z-height that is above the first Z-height, and fiber <NUM>C is at a third Z-height that is above the second Z-height. After exiting the fiber shuffler <NUM>, the fibers <NUM> enter a ferrule <NUM>. The ferrule <NUM> routs the fibers <NUM> so they are arranged into a column. That is, the third fiber <NUM>C is directly above the second fiber <NUM>B, and the second fiber <NUM>B is directly above the first fiber <NUM>A. Accordingly, the optical coupler may translate a row into a column. In an embodiment, the fiber shuffler <NUM> and the ferrule <NUM> may be supported from below by pillars <NUM>. The pillars <NUM> may be supported by the PCB (not shown) or by a portion of the package substrate <NUM>. In the illustrated embodiment, the FAU <NUM>, the optical fibers <NUM>, the fiber shuffler <NUM>, and the ferrule <NUM> are shown as discrete components. However, it is to be appreciated that the FAU <NUM>, the optical fibers <NUM>, the fiber shuffler <NUM>, and the ferrule <NUM> may be molded together as a single component.

The optical coupler described above highlights the coupling of a set of three fibers <NUM>A-C. However, the optical coupler may provide translation of a plurality of optical fibers <NUM>. For example, in <FIG>, a 1X24 row of fibers <NUM> is translated into a 3X8 array at the end of the ferrule <NUM>.

In an embodiment, the fibers <NUM> may be optically coupled to the grating coupler <NUM> by lenses <NUM> and <NUM>. Lens <NUM> may be coupled to the FAU <NUM>, and lens <NUM> may be coupled to the optics die <NUM>. As such, optical signals from the fibers <NUM> may be focused onto the grating couplers <NUM> of the optics die <NUM>. However, it is to be appreciated that one or both of the lenses <NUM> and <NUM> may be omitted in some embodiments.

Referring now to <FIG>, a perspective view illustration of an FAU <NUM> is shown, in accordance with an embodiment. As shown, the FAU <NUM> may comprise a housing for guiding the fibers (not shown) towards a grating coupler <NUM> on an optics die (not shown). Channels <NUM> may be formed in a bottom portion of the FAU <NUM> to receive the fibers. The channels <NUM> may be completely surrounded by the housing of the FAU <NUM>. In an embodiment, the channels <NUM> may comprise a bend in order to change the path of the fibers. For example, the bend in the channels <NUM> may be approximately <NUM>°. In the upper portion of the FAU <NUM>, V-grooves <NUM> may be provided. The V-grooves provide an alignment feature that allows for fibers to be properly inserted into the channels <NUM>.

In the illustrated embodiment, the FAU <NUM> is shown with paths for three fibers. However, it is to be appreciated that the components of the FAU <NUM> may be repeated any number of times in order to provide an FAU <NUM> that accommodates architectures with more fibers. For example, the FAU <NUM> may comprise twenty four paths for fibers.

Referring now to <FIG>, a perspective view illustration of a fiber shuffler <NUM> is shown, in accordance with an embodiment. In an embodiment, the fiber shuffler <NUM> comprises a main body <NUM>. A plurality of trenches <NUM> are provided into the main body <NUM>. Each of the trenches <NUM> may have a V-groove bottom in order to properly align the fibers (not shown). In an embodiment, the trenches <NUM> may have two or more different depths. For example, trenches <NUM>A have a first depth D<NUM>, trenches <NUM>B have a second depth D<NUM>, and trenches <NUM>C have a third depth D<NUM>. The difference in the depths allow for the fibers to be aligned at different heights within the system. In an embodiment, a rigid plate with protrusions or the like (not shown) may press the fibers into the V-groove bottoms.

In the illustrated embodiment, each set of trenches (e.g., trenches <NUM>A-<NUM>C) includes three trenches. The sets of trenches <NUM> may be repeated any number of times in order to accommodate any number of fibers. For example, eight sets of trenches <NUM> may be used to accommodate a system that comprises twenty four fibers. Additionally while sets with three trenches <NUM> are shown, it is to be appreciated that each set may comprise two or more trenches <NUM>.

Referring now to <FIG>, a perspective view illustration of a ferrule <NUM> is shown, in accordance with an embodiment. In an embodiment, the ferrule <NUM> comprises a first end <NUM> and a second end <NUM>. A fiber realignment region <NUM> is provided between the first end <NUM> and the second end <NUM>. A single fiber <NUM> passing through the fiber realignment region <NUM> is show for simplicity. However, it is to be appreciated that the all of the fibers <NUM> pass through the fiber realignment region <NUM> in some embodiments.

As shown in <FIG>, for each set of three fibers <NUM>, the first end of the fibers <NUM><NUM> are not aligned. This is because the fiber shuffler <NUM> has set different Z-heights for the fibers <NUM>. Additionally, no lateral displacement has taken place at this point, so the fibers <NUM> within a set are not aligned above/below each other. During the transition from the first end <NUM> to the second end <NUM>, the fibers <NUM><NUM> are laterally displaced so that the second end of the fibers <NUM><NUM> are aligned in a column. As such, the combination of the FAU <NUM>, the fiber shuffler <NUM>, and the ferrule <NUM> allow for the conversion of a row of fibers into a multi column array. For example, the fibers may be converted from a 1X24 array to a 3X8 array in some embodiments.

Referring now to <FIG>, a perspective view illustration of an optical package <NUM> is shown, in accordance with an embodiment. As shown, the optical package <NUM> comprises a package substrate <NUM> and an IHS <NUM>. A compute die <NUM> and optics dies <NUM> are provided between the package substrate <NUM> and the IHS <NUM>. Each of the optics dies <NUM> are optically coupled to an optical connector <NUM>. For example, six optical connectors <NUM> are shown in <FIG>. However, it is to be appreciated that there may be any number of optical connectors <NUM> to match the number of optics dies <NUM>.

In an embodiment, each of the optical connectors <NUM> may comprise a FAU <NUM>, a fiber shuffler <NUM>, and a ferrule <NUM>. The ferrule <NUM> and the fiber shuffler <NUM> may be supported by pillars <NUM>. The pillars <NUM> may be attached to a board (not shown) that is below the package substrate <NUM>. In other embodiments, the package substrate <NUM> may extend out and provide the support for the pillars <NUM>.

Referring now to <FIG>, a perspective view illustration of an optical system <NUM> is shown, in accordance with an embodiment. In an embodiment, the optical system <NUM> comprises a board <NUM>, such as a PCB. A package substrate <NUM> may be attached to the board <NUM>. An IHS <NUM> may be provided over the package substrate <NUM>. In an embodiment, a compute die (not shown) and a plurality of optics dies (not shown) are provided between the IHS <NUM> and the package substrate <NUM>. Optical connectors <NUM> may be optically coupled to the optics dies.

In an embodiment, the optical system <NUM> may comprise any of the embodiments described above. For example, a lid covering a recess in the package substrate may be provided. A sealant epoxy is be provided to seal the cavity below the lid in some embodiments. Additionally, the optical connector <NUM> may comprise a molded fiber distribution housing between a holder and the ferrule. Embodiments may also include one or more micro channels on various surfaces in order to control the dispensing of various materials. For examples, micro channels may be provided on the IHS <NUM>, the package substrate <NUM>, or on V-grooves of the optics dies.

In the illustrated embodiment, the optical connectors <NUM> exit from the side of the optical system. However, it is to be appreciated that optical connectors similar to those described in <FIG> may replace the illustrated optical connectors <NUM>. In such an embodiment, holes through the IHS <NUM> may be provided to allow access to grating couplers on the optics dies. In an embodiment, such vertical optical connectors may comprise an FAU, a fiber shuffler, and a ferrule.

<FIG> illustrates a computing device <NUM> in accordance with one implementation of the invention. The computing device <NUM> houses a board <NUM>. The board <NUM> may include a number of components, including but not limited to a processor <NUM> and at least one communication chip <NUM>. The processor <NUM> is physically and electrically coupled to the board <NUM>. In some implementations the at least one communication chip <NUM> is also physically and electrically coupled to the board <NUM>. In further implementations, the communication chip <NUM> is part of the processor <NUM>.

These other components include, but are not limited to, volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), flash memory, a graphics processor, a digital signal processor, a crypto processor, a chipset, an antenna, a display, a touchscreen display, a touchscreen controller, a battery, an audio codec, a video codec, a power amplifier, a global positioning system (GPS) device, a compass, an accelerometer, a gyroscope, a speaker, a camera, and a mass storage device (such as hard disk drive, compact disk (CD), digital versatile disk (DVD), and so forth).

The processor <NUM> of the computing device <NUM> includes an integrated circuit die packaged within the processor <NUM>. In some implementations of the invention, the integrated circuit die of the processor may be part of an optical package that comprises optical connectors coupled to optics dies, in accordance with embodiments described herein. The term "processor" may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory.

Claim 1:
An optical package (<NUM>), comprising:
a package substrate (<NUM>);
a compute die (<NUM>) on the package substrate (<NUM>);
an optics die (<NUM>) on the package substrate (<NUM>); an optical connector (<NUM>) coupled to the optics die (<NUM>);
a sealant around the optical connector (<NUM>); and
an integrated heat spreader, IHS, (<NUM>) over the compute die (<NUM>) and the optics die (<NUM>),
wherein channels (<NUM>) and reservoirs (<NUM>) are disposed on a surface of the IHS (<NUM>) facing the package substrate (<NUM>), said channels (<NUM>) fluidically coupled to the reservoirs (<NUM>), wherein the sealant at least partially fills the channels (<NUM>), and wherein the channels are configured to transport excess sealant to the reservoirs (<NUM>) through capillary action.