Active package cooling structures using molded substrate packaging technology

Package assemblies with a molded substrate comprising fluid conduits. The fluid conduits may be operable for conveying a fluid (e.g., liquid and/or vapor) through some portion of the package substrate structure. Fluid conduits may be at least partially defined by an interconnect trace comprising a metal. The fluid conveyance may improve thermal management of the package assembly, for example removing heat dissipated by one or more integrated circuits (ICs) of the package assembly.

BACKGROUND

In electronics manufacturing, integrated circuit (IC) packaging is a stage of semiconductor device fabrication, in which an IC that has been fabricated on a die (or chip) comprising a semiconducting material is encapsulated in an “assembly” or “package” that can protect the IC from physical damage and support electrical contacts that connect the IC to a host circuit board or another package. In the IC industry, the process of fabricating a package is often referred to as packaging, or assembly.

Central processors, power management ICs, and RFIC packages continue to achieve higher power densities. A number of IC packaging technologies include a heat spreader, which is to convey heat from an IC die to an external heat sink. Such passive cooling may however become inadequate in the near future, and active cooling technologies may be needed. However, active cooling through an IC package remains challenging, for example due to a variety of manufacturing difficulties associated with a given packaging technology. Package technologies that can accommodate active cooling at a minimal incremental cost may prove commercially advantageous, enabling longer IC assembly lifetimes in more extreme field environments, and/or higher IC device power densities, for example.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The terms “over,” “under,” “between,” and “on” as used herein refer to a relative position of one component or material with respect to other components or materials where such physical relationships are noteworthy. For example in the context of materials, one material or material disposed over or under another may be directly in contact or may have one or more intervening materials. Moreover, one material disposed between two materials or materials may be directly in contact with the two layers or may have one or more intervening layers. In contrast, a first material or material “on” a second material or material is in direct contact with that second material/material. Similar distinctions are to be made in the context of component assemblies.

Examples of active cooling structures that may be integrated within a substrate of a package assembly (e.g., single die, multi-die, 3D die stacks, etc.) are described herein. In accordance with some exemplary embodiments, a molded substrate integrates fluid conduits within a package substrate structure. These fluid conduits are operable for conveying a fluid (e.g., liquid) through some portion of the substrate. The fluid conveyance may improve thermal management of the package assembly, for example by removing heat dissipated by one or more integrated circuits (ICs) of the package assembly. Embodiments described herein may be particularly advantageous where cooling (active, or otherwise) on a top-side a package assembly is hindered. For example, when an interposer is over a top side of an IC die, or multiple die are stacked (e.g., memory IC over a logic IC), or the use of a heat spreader on the top side of the assembly is otherwise difficult, and, as a result, heat removal through the top side of a package assembly may be insufficient. Active cooling through a bottom side of an IC die may be achieved through use of the fluid conduit architectures described herein.

Molded substrate packaging technology comprises a preform substrate that includes an interconnect leadframe embedded within an electrical insulator (dielectric) material. During molded substrate manufacture, the dielectric material may be patterned and any number of metallization layers plated up from a sacrificial carrier, for example. Upon removal of the carrier, the mold preform can then be employed as a substrate for an IC package assembly. With structural benefits of the mold preform, the interconnect metallization may be of a significantly finer geometry (e.g., smaller trace dimensions) than a discrete leadframe. Electrical and thermal properties of a molded preform may also be superior to a discrete leadframe. Embodiments described further below integrate one or more fluid conduits into a substrate structure that comprises one or more molded preforms. Top side interconnects (e.g., top-side ball grid array, or TSBGA) on an uppermost molded preform may couple the substrate structure to one or more IC dies, while bottom side interconnects (e.g., bottom-side ball grid array, or BSBGA) may further couple a lowermost molded preform to a system-level interface (e.g., circuit board, etc.). The fluid conduits within the molded substrate structure may implement active cooling of the IC dies, for example with a fluid inlet and outlet coupled to opposite ends of a fluid conduit. A fluid, such as any suitable heat transfer liquid, may be conveyed through the fluid conduits, for example as part of a system-level coolant loop, to remove heat from the package assembly during operation of the IC dies.

In accordance with some embodiments,FIG.1Aillustrates a flow diagram of methods101for fabricating an IC package assembly comprising a fluid conduit suitable for active cooling, in accordance with some embodiments. Methods101begin at block105where a molded preform is received. The molded preform includes interconnect metallization within a dielectric mold material. The interconnect metallization may comprise any number of interconnect metallization (e.g., trace) levels. The dielectric mold material may have any suitable composition. At block120, one or more fluid conduits are formed in the molded preform. In some embodiments, a fluid conduit comprises a cavity within the molded preform, for example within one or more interconnect metallization levels. In some alternative embodiments, methods101optionally further include block115where an additional molded preform is received and joined to the molded preform received at block105. One or more fluid conduits may then be formed within features of the joint between two molded preforms.

Once the fluid conduit(s) are present within the substrate structure, methods101continue at block125where an IC die is received. The IC die may comprise one or more integrated circuits, and may for example by any of a microprocessor die, a memory die, a wireless/RF communication die, or a system-on-chip (SoC) die including one or more of microprocessor circuitry, memory circuitry, or RF transmitter/receiver circuitry, for example.

At block130, the die received at block125is attached to the substrate structure. In exemplary embodiments, the IC die is attached, for example with solder features, to the substrate structure so that the IC die is located proximal (e.g., directly over) a fluid conduit of the substrate structure. Any number of IC dies may be attached at block130, in either a 2D die layout, or a 3D die layout (i.e., die stack). Any die attachment process may be implemented at block130, for example interconnect features on a surface of an IC die may be attached to a ball grid array (BGA) on a surface of the substrate structure.

With at least one IC die attached to the substrate structure, methods101may continue according to any compatible packaging assembly process. In the illustrated example, methods101continue at block140where a mold compound is applied around the IC die. Any suitable mold material may be applied at block140to form any suitable overmold structure, for example encapsulating one or more IC dies within a package assembly. Methods101are then completed at block150where any compatible packaging assembly and/or electrical test process(es) may be performed upon the package assembly.

Following completion of methods101, the package assembly may be affixed to a system-level component, such as, but not limited to, a printed circuit board (PCB), or other interface. The system-level component may be part of any electronic device (e.g., wireless handset device, notebook computer device, networked computer server, automobile, autonomous platform, etc.).

FIG.1Billustrates methods102for integrating a package assembly with fluid conduits into a computer system or platform. Methods102begin at block155where a package assembly is received. The package assembly received at block155includes a substrate structure with fluid conduits, which may, for example, have been assembled according to methods101. Methods102continue at block160where the package assembly is attached to interconnect features on a system board. Any technique known to be suitable for attaching a package assembly may be employed. In some embodiments, a substrate structure is attached to system-level interconnect features through a bottom side BGA (BSBGA) present on the substrate structure. At block170, an active cooling recirculation loop of the system is coupled a fluid conduit present in the substrate structure. In one example, a system level fluid supply is coupled to an inlet end of a fluid conduit in the substrate structure. In a further example, a system level fluid return is coupled to an outlet end of the fluid conduit with a length of the fluid conduit coupling the inlet and outlet ends such that a heat transfer fluid that is to be conveyed through the system-level cooling loop passes through a length of the fluid conduit proximal to one or more IC dies in the package assembly. In some exemplary embodiments, coupling of the fluid conduit inlet and/or outlet ports comprises a reflow of one or more solder features joining the fluid conduit inlet and/or outlet ends to mating features of the system component (e.g., PCB).

FIG.1Cillustrates a flow diagram of methods103for fabricating an IC package assembly comprising a fluid conduit suitable for active cooling, in accordance with some embodiments. Methods103may be practiced as one implementation of the methods101that were illustrated inFIG.1A. Methods103begin at block111where a first molded preform comprising a first interconnect structure embedded within a first mold material is received. A second molded preform comprising a second interconnect structure embedded within a second mold material is received at block112. The two preforms are then assembled together at block121to form a substrate structure. In one example, interconnect features on one side of the mold preform received at block111are soldered to interconnect features on one side of the mold preform received at block112to form the substrate structure. A subset of the interconnect features joining the two molded preforms may define one or more walls of a lateral run (e.g., a “length”) of a fluid conduit that is suitable for confining a fluid between the two molded preforms (i.e., within the substrate structure). In some embodiments, the fluid conduit comprises an opening at a perimeter edge of the substrate structure, for example where a heat transfer fluid supply and/or return may be coupled to and/or from the lateral conduit length. In some other embodiments, the fluid conduit lacks any openings at the edge of the substrate structure. For one such embodiment, methods103further include the formation of one or more through substrate vias (TSVs) that extend through at least the thickness of one of the molded preforms. The TSVs may be suitable for confining/conveying a fluid through one of the molded preforms, and the TSVs may intersect the lateral fluid conduit within the substrate structure (e.g., located between the two molded preforms). The TSVs may therefore function as vertical conduit runs and/or inlet/outlet ports of the substrate structure.

Methods103continue at block131where at least one IC die comprising at least one integrated circuit is attached to a first side of the substrate structure, and more specifically to interconnect features on a top surface of a top molded preform. At block145, solder features (e.g., solder balls or bumps) are attached to a second side of the substrate structure, and more specifically to interconnect features on a bottom surface of a bottom molded preform. Methods103complete at block150where the package assembly is completed and/or tested. For example, an overmold process may be performed to encapsulate the IC die(s), etc. The package assembly is then ready to be attached to a system-level component by the bottom-side solder features.

A variety of package assembly structures, each having any number of fluid conduit features, may be fabricated according to the methods described above. Exemplary package assembly structures illustrating some illustrative fluid conduit features are described below. Although such package assembly structures may be fabricated according to one or more of the methods described above, similar structures may also be fabricated according to alternative methods.

FIG.2A-2Dillustrate cross-sectional views of an IC package assembly including a multilayered molded substrate structure comprising a fluid conduit at various stages of assembly, in accordance with some embodiments.FIG.2Aillustrates a sectional view of a molded preform201. Molded preform201includes a metallization level211embedded within a dielectric material223. Metallization level211includes any number of metallization features, such as traces216. The metallization features may be of any material having suitable electrical conductivity, such as, but not limited to, copper, an alloy thereof, or another metal. Dielectric material223may be any suitable material, such as, but not limited to, mold material comprising an epoxy-based, or silicone-based matrix. Such matrix materials may be polymeric, with some examples of silicone-based polymers being polysiloxanes that further comprise silicon, oxygen, and carbon. In addition to the matrix material, dielectric material223may further comprise one or more fillers. In some embodiments, at least one of the fillers and matrix is carbonaceous (e.g., graphite, etc.).

Molded preform201further includes interconnect features in another metallization level212. These interconnect features may be posts, or pillars, for example, that extend beyond a surface of dielectric material223in a manner that makes them suitable for solder contacts. Each interconnect feature within metallization level212may electrically couple to any number of features within metallization level211. In the illustrated example, each of interconnect features217,218and219interconnect metallization levels211and212. Molded preform201may be formed according to any suitable techniques. In some embodiments, molded preform201is fabricated by forming a resist mask over a sacrificial carrier, plating metallization level211according to the resist mask, removing the resist mask, and molding dielectric material223around the plated metallization features. Dielectric material223may then be planarized (polished) to be co-planar with traces216. Posts of metallization level212may then be plated upon exposed portions of metallization level211, and the sacrificial carrier then removed to arrive at molded preform201.

FIG.2Billustrates a sectional view of a molded preform210. Molded preform210also includes metallization levels embedded within a dielectric material229. In the illustrated example, molded preform210includes metallization levels211,212,213,214, and215, but more (or fewer) metallization levels may be present. Conductive interconnects231,232and233are in contact with a surface of features in metallization level211. Conductive interconnects231-233may be any known to be suitable for electrically coupling an IC die, such as, but not limited to, solder features (e.g., solder balls, solder bumps, microbumps, etc.). Dielectric material229may again be any suitable material, such as, but not limited to, mold material comprising an epoxy-based, or silicone-based matrix. In some embodiments dielectric material229has substantially the same composition as dielectric material223(FIG.2A). Metallization levels211-215may comprise any suitable metal(s), such as, but not limited to copper.

FIG.2Cillustrates a sectional view of a substrate structure220that includes molded preform201attached to molded preform210. In this example, features in metallization level212of molded preform201are soldered to features in metallization level211of molded preform210. As shown, interconnects231-233and/or interconnect features217,218,219and221stand-off molded preform201from an opposing nearest surface of molded preform210. Fluid conduits240may reside within the standoff between molded preforms201and210. Fluid conduits240may be separate channels, for example with interconnect feature218forming a boundary between two adjacent fluid conduits240. Alternatively fluid conduits240may be portions of a larger conduit with interconnect feature218merely being a post around which a fluid may be present. At least one interconnect feature defines a sidewall of fluid conduit(s)240with opposing surfaces of molded preforms201,210enclosing the bottom and top of the fluid conduit(s)240, respectively. In the illustrated example, traces216and226at least partially define a top and bottom surface of fluid conduit(s)240with interconnect217defines a sidewall of fluid conduit(s)240. As such, at least a portion of fluid conduit(s)240may comprise an interconnect metallization trace.

FIG.2Dillustrates a sectional view of an IC package assembly225that includes an IC die250attached to substrate structure220. A package mold material260is over IC die250. IC die250is coupled to a top surface of substrate structure220by solder interconnect features248(e.g., solder bumps, balls, etc.) with package mold material260therebetween. IC die250may be any die that includes one or more integrated circuits, such as, but not limited to, any of the examples described above. IC package assembly225further includes bottom-side solder features249in contact with a bottom metallization level of substrate structure220. Solder features249may be solder balls or bumps, for example, suitable for coupling IC package assembly225to a system-level component, such as a PCB (not depicted).

As illustrated, no portion of IC die250is directly exposed to fluid conduit240with surfaces of IC die250instead separated from fluid conduit240by a portion of substrate structure220. Interconnect features218and219electrically couple IC die250, through a solder feature231, to one or more additional metallization features227within substrate structure220. The interconnect features218and219may therefore also be referred to herein as electrical interconnect structures. Interconnect feature217is not in electrical contact with IC die250, and may instead function as a sidewall of fluid conduit(s)240, for example with interconnect feature217and solder feature232together presenting a barrier suitable for confining a fluid within fluid conduit(s)240. Interconnect feature217may also have other functions, for example as a thermal via, or may also make electrical contact to IC die250(e.g., to a ground plane, power plane, or signal I/O). In this example therefore, fluid conduit240is between metal traces above and below (e.g., metallization features216,226) and with a metal trace sidewall (e.g., interconnect feature217).

FIG.2Eillustrates a plan view of the IC package assembly225, in accordance with some embodiments. The plan view shown is through a z-plane that intersects interconnect features217,218,219and221. Dashed lines are out of the z-plane (e.g., below or above) and solid lines are on the z-plane. For reference, the A-A′ line inFIG.2Edenotes the cross sectional plane illustrated inFIG.2D. As shown inFIG.2E, interconnect feature217is a metal trace that extends between opposite sidewalls of package assembly225with fluid conduit240extending a lateral length (e.g., y-axis) between a fluid inlet280and a fluid outlet290. A second interconnect feature277is another trace presenting a continuous barrier to fluid flow along the length of fluid conduit240, confining conduit240to a region of the IC package assembly225below IC die250.

Fluid conduit240extends beyond the footprint of IC die250, and has a length (e.g., y-dimension) that is longer than that of a sidewall of IC die250. During operation of IC package assembly225, a fluid may be conveyed through fluid conduit240, entering at fluid inlet280and discharging from fluid outlet290. An illustrative fluid flow pattern within the lateral run below IC die250is represented by straight arrows inFIG.2E. In this example, IC die250(e.g., I/O signal ports) is electrically coupled to the substrate structure through interconnect features218and219, which extend through, and/or are surrounded by, fluid conduit240. Features218and219may be considered vias or traces, but at any rate have lengths (e.g., y-axis) smaller than that of features217and277. With this fluid conduit architecture, it may be advantageous for fluid conduit240to convey a dielectric heat transfer fluid that is sufficiently electrically insulative such that multiple metallization features (e.g., interconnect features218and219) directly immersed in the heat transfer fluid need not be electrically shorted. Exemplary dielectric heat transfer fluids include aliphatics, fluorocarbons and silicones.

In some embodiments, a fluid conduit is physically separated from one or more package substrate metallization features that further convey signals to/from an IC die. In accordance with some embodiments, a fluid conduit prevents fluid contact with any package metallization features that convey IC electrical signals through the package substrate.FIG.3A-3Dillustrate cross-sectional views of an IC package assembly evolving to include a multilayered molded substrate structure comprising a fluid conduit, in accordance with some embodiments.FIG.3Aillustrates a sectional view of a molded preform301. Molded preform301includes metallization levels311,312,313,314and315embedded within a dielectric material223. Molded preform301further includes interconnect features317,318and319(e.g., posts, or pillars) that extend beyond a surface of dielectric material223in a manner that makes them suitable for contacting a solder feature. In the illustrated example, only interconnect feature319is electrically coupled to a top-side solder feature (e.g., bump348).

FIG.3Billustrates a sectional view of a molded preform310. Molded preform310also includes metallization levels311-315embedded within a dielectric material229. Conductive interconnects (e.g., solder features341,342and343) are in contact with a surface of features in metallization level311. Solder features341-343may be solder balls, solder bumps, microbumps, for example. Metallization level315includes features (e.g., pads) to receive conductive interconnects (e.g., solder features), and may alternatively include posts or pillars (e.g., like interconnect features317,318and319).

FIG.3Cillustrates a sectional view of a substrate structure320that includes molded preform301attached to molded preform310. In this example, interconnect features (e.g.,317,318and319) on a bottom side of molded preform301are connected to metallization level311(e.g., by solder features341-343) on a top side of molded preform310. As shown, solder features341-343and/or interconnect features317-319stand-off molded preform301from a nearest surface of molded preform310. Fluid conduits may again reside within the standoff between molded preforms301, but for exemplary embodiments where electrical pathways are isolated from the fluid conduit, the fluid conduit may be confined exclusively by non-electrical interconnect features.

FIG.3Dillustrates a sectional view of an IC package assembly325that includes IC die250attached to substrate structure320. Package mold material260is over IC die250, and may also be present between die solder interconnect features348(e.g., solder bumps, balls, etc.). Alternatively, a separate underfill material may be between IC die250and substrate structure320. IC package assembly325further includes bottom-side solder features249in contact with a metallization level within substrate structure320. Interconnect feature317physically couples through solder feature341, to one or more additional metallization features326within substrate structure320. As further shown, interconnect feature319electrically couples IC die250, through solder feature343, to one or more additional metallization features327within substrate structure320. In this example, interconnect features317and318each function as one sidewall of a fluid conduit340and do not further function as electrical connection(s) to IC die250. Interconnect feature317and solder feature341together may present a barrier suitable for confining a fluid within a fluid conduit340. Interconnect features317-318may also have other functions, for example as thermal vias, etc., and may even make electrical contact to IC die250(e.g., to a ground plane, power plane, or signal I/O). However, with interconnect features317and318defining fluid conduit340, interconnect feature319is electrically isolated from any fluid that is to be conveyed through fluid conduit340. Hence, a dry zone350may surround interconnect feature319. In the illustrated example, dry zone350is between two fluid conduits340such that two adjacent fluid conduits340are separated from each other by two interconnect features318and321that are each a sidewall of one of one of the conduits340.

FIG.3Eillustrates a plan view of the IC package assembly325, in accordance with some embodiments. The plan view shown is through a z-plane that intersects interconnect features317,318,319and321. Dashed lines are out of the z-plane (e.g., below or above) and solid lines are on the z-plane. For reference, the A-A′ line inFIG.3Edenotes the cross sectional plane illustrated inFIG.3D. As visible in the plan view, interconnect features317and318are substantially parallel traces that define a longitudinal length of fluid conduit340. Interconnect features317and318extend between opposite sidewalls of package assembly325with fluid conduit340having a lateral length (e.g., y-axis) between a fluid inlet280and a fluid outlet290. Solder feature341is also illustrated to be continuous along the length of interconnect feature317. Solder341and interconnect feature317may, for example, provide a continuous barrier to fluid flow along the length of a fluid conduit340. A similar solder feature is continuous along the length of interconnect feature318to provide a second continuous barrier to fluid flow along the length of fluid conduit340.

Fluid conduit340extends beyond the footprint of IC die250, and has a length (e.g., y-dimension) that is longer than that of a sidewall of IC die250. During operation of IC package assembly325, a fluid may be conveyed through fluid conduit340, entering at fluid inlet280and discharging from fluid outlet290and having some fluid flow pattern (e.g., represented by straight arrows inFIG.3E) within the lateral run below IC die250. In this example, IC die250(e.g., I/O signal ports) is electrically coupled to the substrate structure through interconnect feature(s)319, with is isolated from fluid conduit340. Feature(s)319may have any lateral dimensions. Another fluid conduit340is further isolated from interconnect feature(s)316by interconnect feature321, that may be similarly attached to a solder feature. With this fluid conduit architecture, fluid conduit340may convey any heat transfer fluid, including those that are not considered to be dielectric fluids since metallization features electrically coupled to IC die250are not directly exposed to any heat transfer fluid.

In some embodiments, a molded substrate structure includes a fluid conduit having a longitudinal length that extends through at least a partial thickness of the substrate structure. Hence, in addition to lateral runs over a substrate structure, a fluid conduit may also include vertical runs. With vertical runs, a fluid conduit need not have an inlet and/or outlet on edges of the substrate structure, for example. In some embodiments, a vertical conduit run comprises a through-substrate via (TSV). Such a fluid conduit TSV may include one or more metallization features of a molded preform as a conduit sidewall. Sidewalls of the TSV may also include mold material of a molded preform.FIG.4A-4Billustrate cross-sectional views of an IC package assembly420including a molded substrate structure comprising a fluid conduit TSV, in accordance with some embodiments. As shown inFIG.4A, an interconnect feature417of a molded preform401is attached by solder features341to a TSV metallization features426of a molded preform410. Fluid conduit440is located between molded preforms401and410, and comprise a TSV475that extends through the z-thickness of molded preform410. Such a TSV may be drilled (e.g., laser or mechanical) through a preform, or may be the result of an iterative patterning process (e.g., with a sacrificial material that is removed selectively to mold material229).

FIG.4Billustrates a plan view of the IC package assembly420, in accordance with some embodiments. The plan view shown is through a z-plane that intersects interconnect features417,418and421. Dashed lines are out of the z-plane (e.g., below or above) and solid lines are on the z-plane. For reference, the A-A′ line inFIG.3Edenotes the cross sectional plane illustrated inFIG.4A. As visible in the plan view, TSVs475are at opposite ends of a lateral run of fluid conduit(s)440with TSVs475intersecting a spacing or channel between interconnect features417and418. Fluid conduits440may therefore have an inlet and/or outlet at a bottom surface of molded preform410. For this embodiment also, electrical connections to an IC die (e.g., through interconnect features421) are isolated from fluid conduits340, but in the alternative may also be exposed to the fluid conduits.

In some embodiments, a fluid conduit is embedded within a molded preform. Such a fluid conduit may be completely sealed within the molded preform, or may include an inlet/outlet port. Embedded fluid conduits may not rely upon solder and/or interconnect features in the manner described above, but may otherwise share one or more structural features with the fluid conduits described above.

FIG.5illustrates a flow diagram of methods501for assembling an IC assembly including a fluid conduit suitable for active cooling, in accordance with some embodiments. Methods501again begin at block110where a molded preform is received. The molded preform may have one or more of the attributes described elsewhere herein, and may further comprise a sacrificial material that is to be removed selectively to the interconnect metallization and/or mold material at block520. Once a cavity is formed in the molded preform, the cavity may be filled with a heat transfer fluid and/or a variety of components to facilitate active cooling of an IC die. For example, the embedded cavity may be fitted with inlet and outlet ports that interface with a system-level cooling loop. As another example, a heat pipe device may be positioned (e.g., by pick-and-place) within the molded preform cavity as a closed-loop cooling system for an IC die that is to be subsequently attached to the molded preform. Such a heat pipe device may be integrated into the molded preform such that one or more metallization features of the molded preform that are exposed by the cavity may implement hot and/or cold sides of the heat pipe upon the addition of a heat transfer fluid to the cavity. Optionally, a porous “wick” material may also be applied to the cavity at block525, for example. The cavity may then be sealed, for example during the package assembly process, and an IC die attached to (top) surface of the preform at block531. At block545, solder features may be applied to a bottom surface of the preform, and package assembly and/or test performed at block150.

FIG.6Aillustrates a cross-sectional view of an IC package assembly625including molded substrate structure601comprising a fluid conduit640, in accordance with some embodiments. As illustrated, fluid conduit640is embedded within substrate structure601, for example with a bottom surface of the conduit comprising a first interconnect metallization level315, and a top surface of the conduit comprising a second interconnect metallization level313. Sidewalls of fluid conduit640comprise interconnect metallization features661and662, of an intervening metallization level314. IC package assembly625may be formed during package assembly (e.g., according to methods501), or may be formed during the fabrication of a molded preform that is then utilized in subsequent package assembly.

FIG.6Billustrates a plan view of the IC package assembly625, in accordance with some embodiments. The plan view shown is through a z-plane that intersects interconnect metallization features661and662. Dashed lines are out of the z-plane (e.g., below or above) and solid lines are on the z-plane. For reference, the A-A′ line inFIG.6Bdenotes the cross sectional plane illustrated inFIG.6A. As visible in the plan view, interconnect features661and662are substantially parallel traces that define a longitudinal length of fluid conduit640. Interconnect features661and662extend between opposite sidewalls of package assembly625with fluid conduit640having a lateral length (e.g., y-axis) between a fluid inlet280and a fluid outlet290. In contrast to fluid conduits described elsewhere herein, fluid conduit640does not incorporate a solder feature along the length of the conduit. Instead, sidewalls of fluid conduit640are defined only by interconnect metallization traces embedded within a single molded preform.

Fluid conduit640extends beyond the footprint of IC die250, and has a length (e.g., y-dimension) that is longer than that of a sidewall of IC die250. During operation of IC package assembly625, a fluid may be conveyed through fluid conduit640, entering at fluid inlet280and discharging from fluid outlet290with an illustrative fluid flow pattern within the lateral run below IC die250represented inFIG.6Bby straight arrows. In this example,

IC die250is electrically coupled to the substrate structure through interconnect feature(s)661and662, which also define fluid conduit640. In some examples, interconnect features661and662maintain a single reference voltage for IC die250with no voltage potential then applied across a coolant fluid that may be contained within, and/or conveyed through, fluid conduit640. Interconnect features661and662may be part of a ground plane of package assembly625, may be electrically floating, or may be powered to a power rail level supplied to IC die250, for example. In other embodiments, an embedded fluid conduit may be contained within metallization traces that are not electrically coupled to any signal, power, or ground port of an IC die.

As noted above in the context of methods501, in addition to facilitating active cooling loops that are open to a coolant fluid supply/return external of an IC package assembly, fluid conduits in accordance with embodiments herein may also be suitable for closed loop cooling systems that are fully contained with a molded substrate and/or IC package assembly. A heat pipe device is one example of an active cooling system where no system-level fluid supply/return is needed. A heat pipe device implemented in an assembly process may be substantially as described above with hot and cold sides of the heat pipe device on two different molded preforms that are attached by interconnect features, such as a solder features. Alternatively, an embedded heat pipe device may be implemented in an assembly process where a sacrificial material is removed from a molded substrate during the assembly process and a heat pipe device installed or constructed. Upon removing a sacrificial material to form a fluid conduit for example, a portion of the fluid conduit exposed to an exterior surface (e.g., edge sidewall) of a package substrate structure may be plugged to isolate the fluid conduit. In still other embodiments, the heat pipe device may be formed upstream of assembly (e.g., during fabrication of a molded preform).

FIG.7Aillustrates a cross-sectional view of an IC package assembly725including a molded substrate structure701that further comprises a heat pipe device740, in accordance with some embodiments. Heat pipe device740comprises a fluid conduit that is closed rather than the open conduit640(FIG.6A-6B).FIG.7Billustrates a plan view of the IC package assembly725, in accordance with some embodiments. The plan view shown is through a z-plane that intersects interconnect metallization features661and662. Dashed lines are out of the z-plane (e.g., below or above) and solid lines are on the z-plane. For reference, the A-A′ line inFIG.7Bdenotes the cross sectional plane illustrated inFIG.7A. As visible in the plan view, a sidewall of heat pipe device740comprises a molded preform metallization feature661that forms a continuous perimeter about an interior region, or cavity, within which a heat transfer fluid is to be conveyed between hot and cold surfaces of the heat pipe device.

Heat pipe device740is a closed system that utilizes evaporative cooling to move heat from a heat source (e.g., from a hot side coupled to IC die250) to a heat sink (e.g., to a cold side component coupled to solder features249). Heat transfer of heat pipe device740operates on phase transition principle. For example, a fluid conduit may include a porous material741occupying a section of the conduit, and an open space or passageway within another section of the conduit. The conduit further includes a heat transfer fluid, more or less of which may be in liquid and/or vapor phase as a function of the temperature and/or physical location of the fluid within the heat pipe device. The liquid phase of the heat transfer fluid in contact with the hot side of the conduit may evaporate, thereby absorbing heat from the hot side. The resulting vapor phase of the heat transfer fluid may travel along the open passageway of the conduit towards the cold side. Once the vapor phase of the heat transfer fluid is at or near the cold side, the vapor may condense back to the liquid phase, thereby releasing latent heat at the cold side. The liquid phase of the heat transfer fluid is then transported back to the hot side through the porous material, for example, by capillary action. Thus, in heat pipe device740, a change of phase of the heat transfer fluid between liquid and vapor aids in transfer of heat from the hot side (proximal to IC die250) to the cold side (proximal to solder features249), thereby cooling IC die250.

Heat pipe device740is embedded within substrate structure701, with a metallization trace (or other feature) of metallization level313functional as a hot-side surface and metallization trace (or other feature) of metallization level315functional as a cold-side surface. Sidewalls of heat pipe device740include material that can hermitically seal the fluid conduit. In the illustrated example, interconnect features661, each comprising a metal (e.g., copper), further serve to seal the fluid conduit. Hence, the material employed as electrical interconnects of molded preform701are further employed to seal heat pipe device740. Interconnect metallization may completely isolate heat pipe device740from mold material223, for example.

Heat pipe device740may contain a heat transfer fluid (not depicted). The heat transfer fluid may be based on an application of the package assembly725. For example, the selection of the heat transfer fluid may be based on an anticipated maximum temperature at the hot side, a desired amount of heat to be transferred, etc. Exemplary heat transfer fluids include those fluids described above as well as water, IPA, ethanol, methanol, and R1234ze). Porous material741may be any material known to be suitable for the application that is further suitable to the package assembly process and/or molded preform fabrication process. In some examples porous material741is a sol-gel material derived from a colloidal solution (sol) that acts as the precursor for an integrated network (or gel) of either discrete particles or network polymers.

FIG.8is a functional block diagram of an electronic computing device800, in accordance with an embodiment of the present invention. Device800further includes a motherboard802hosting a number of components, such as, but not limited to, a processor804(e.g., an applications processor). Processor804may be physically and/or electrically coupled to motherboard802. In some examples, processor804includes an integrated circuit die packaged with active package cooling structures within a molded packaging substrate, for example as described elsewhere herein. In general, the term “processor” or “microprocessor” 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 further stored in registers and/or memory.

In various examples, one or more communication chips806may also be physically and/or electrically coupled to the motherboard802. In further implementations, communication chips806may be part of processor804. Depending on its applications, computing device800may include other components that may or may not be physically and electrically coupled to motherboard802. These other components include, but are not limited to, volatile memory (e.g., DRAM832), non-volatile memory (e.g., ROM835), flash memory (e.g., NAND or NOR), magnetic memory (MRAM830), a graphics processor822, a digital signal processor, a crypto processor, a chipset812, an antenna825, touchscreen display815, touchscreen controller865, battery816, audio codec, video codec, power amplifier821, global positioning system (GPS) device840, compass845, accelerometer, gyroscope, speaker820, camera841, and mass storage device (such as hard disk drive, solid-state drive (SSD), compact disk (CD), digital versatile disk (DVD), and so forth), or the like. In some exemplary embodiments, at least one of the functional blocks noted above comprise an IC package assembly including active package cooling structures within a molded packaging substrate, for example as described elsewhere herein.

Communication chips806may enable wireless communications for the transfer of data to and from the computing device800. The term “wireless” and its derivatives may be used to describe circuits, devices, systems, methods, techniques, communications channels, etc., that may communicate data through the use of modulated electromagnetic radiation through a non-solid medium. The term does not imply that the associated devices do not contain any wires, although in some embodiments they might not. Communication chips806may implement any of a number of wireless standards or protocols, including but not limited to those described elsewhere herein. As discussed, computing device800may include a plurality of communication chips806. For example, a first communication chip may be dedicated to shorter-range wireless communications, such as Wi-Fi and Bluetooth, and a second communication chip may be dedicated to longer-range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others.

FIG.9illustrates a mobile computing platform and a data server machine employing a IC package assembly including active package cooling structures within a molded packaging substrate, for example as described elsewhere herein. Computing device800may be found inside platform905or server machine906, for example. The server machine906may be any commercial server, for example including any number of high-performance computing platforms disposed within a rack and networked together for electronic data processing, which in the exemplary embodiment includes a package assembly950including active package cooling structures within a molded packaging substrate, for example as described elsewhere herein. The mobile computing platform905may be any portable device configured for each of electronic data display, electronic data processing, wireless electronic data transmission, or the like. For example, the mobile computing platform905may be any of a tablet, a smart phone, laptop computer, etc., and may include a display screen (e.g., a capacitive, inductive, resistive, or optical touchscreen), a chip-level or package-level integrated system910, and a battery915.

Whether disposed within the integrated system910illustrated in the expanded view920, or as a stand-alone chip within the server machine906, IC package assembly950may include active package cooling structures within a molded packaging substrate, for example as described elsewhere herein. Assembly950may be further coupled to a board, a substrate, or an interposer960along with, one or more of a power management integrated circuit (PMIC)930, RF (wireless) integrated circuit (RFIC)925including a wideband RF (wireless) transmitter and/or receiver (TX/RX) (e.g., including a digital baseband and an analog front end module further comprises a power amplifier on a transmit path and a low noise amplifier on a receive path), and a controller935. A coolant loop955, for example including a heat exchanger and a recirculation system is implemented at a system board level or platform-level (off-board). Coolant loop955may be coupled into IC package assembly950, for example.

Functionally, PMIC930may perform battery power regulation, DC-to-DC conversion, etc., and so has an input coupled to battery915and with an output providing a current supply to other functional modules. As further illustrated, in the exemplary embodiment, RFIC925has an output coupled to an antenna (not shown) to implement any of a number of wireless standards or protocols, including but not limited to Wi-Fi (IEEE 802.11 family), WiMAX (IEEE 802.16 family), IEEE 802.20, long term evolution (LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT,

Bluetooth, derivatives thereof, as well as any other wireless protocols that are designated as 3G, 4G, 4G, and beyond.

It will be recognized that the invention is not limited to the embodiments so described, but can be practiced with modification and alteration without departing from the scope of the appended claims. For example the above embodiments may include specific combinations of features as further provided below.

In first examples, a microelectronic device package assembly comprises a substrate structure comprising one or more traces adjacent to a mold material, wherein the traces comprises a metal. The assembly comprises an integrated circuit (IC) die physically coupled to the substrate structure, and electrically coupled to at least one of the traces, and a fluid conduit within the substrate structure, wherein at least a portion of the fluid conduit comprises the metal.

In second examples, for any of the first examples the fluid conduit comprises an inlet to receive a fluid into the substrate structure and an outlet to discharge the fluid from the substrate structure with a length of the conduit therebetween.

In third examples, for any of the second examples the die is over at least a portion of the fluid conduit, and wherein the length of the fluid conduit is greater than a length of the die.

In fourth examples, for any of the first through the third examples, the substrate structure comprises a first and second substrate, the first substrate bonded to the second substrate by a plurality of solder features, and wherein the fluid conduit is between the first and second substrate.

In fifth examples, for any of the first examples the die is bonded to the first substrate, the fluid conduit comprises an inlet to receive a fluid into the substrate structure and an outlet to discharge the fluid from the substrate structure, and the fluid conduit comprises a metal trace of the first substrate attached by solder to a metal trace of the second substrate.

In sixth examples, for any of the first through the fifth examples the fluid conduit comprises a lateral run between a first conductive via structure and a second conductive via structure, and the first conductive via structure is to convey the fluid to the lateral run, and the second conductive via structure is to covey the fluid from the lateral run.

In seventh examples, for any of the first through the sixth examples the fluid conduit further comprises solder, the solder bonded to the metal.

In eighth examples, for any of the first through seventh examples the fluid conduit comprises a heat pipe sealed within the substrate structure.

In ninth examples, a microelectronic assembly comprises the package structure of any of the first through eighth examples, and the fluid conduit comprises a first conduit having a sidewall comprising a first trace and a second conduit having a sidewall comprising a second trace.

In tenth examples, for any of the ninth examples the first and second conduits are separated from each other by the first and second traces, and the IC die is electrically coupled to a conductive interconnect located between the first and second conductive traces.

In eleventh examples, for any of the ninth through tenth examples each of a first sidewall, a second sidewall, a top side, and a bottom side of the channel comprises a conductive trace.

In twelfth examples, for any of the eleventh examples at least one of the first sidewall, the second sidewall, the top side or the bottom side of the channel is adjacent the mold material.

In thirteenth examples for any of the ninth through twelfth examples, the substrate structure comprises a first mold material; the IC die is embedded within a second mold material, the IC die is coupled to the substrate structure through solder features, and the fluid conduit is separated from the IC die by at least the first mold material.

In fourteenth examples, for any of the ninth through thirteenth examples, at least one of the first sidewall or the second sidewall comprises one or more of copper or solder.

In fifteenth examples, for any of the ninth through fourteenth examples the channel comprises a through-substrate via structure, and wherein a sidewall of the through-substrate via structure comprises a first interconnect trace level of the substrate structure and a second interconnect trace level of the substrate structure, in contact with the first interconnect trace level.

In sixteenth examples, a method of fabricating a microelectronic package assembly comprises forming a fluid conduit within a package substrate structure, the fluid conduit at least partially defined by an interconnect trace comprising a metal, the trace adjacent to a first mold compound, and the fluid conduit extends a length of the substrate. The method further comprises affixing an integrated circuit (IC) die to a surface the package substrate structure, the IC die over the fluid conduit. The method further comprises forming a second mold compound around the IC die, wherein at least one of the first and second mold compounds separates the IC die from the fluid conduit.

In seventeenth examples, for any of the sixteenth examples forming the fluid conduit comprises affixing a first substrate to a second substrate by soldering an interconnect trace of the first substrate to an interconnect trace of the second substrate, wherein the interconnect trace of the first substrate is adjacent to a first mold compound, and the interconnect trace of the second substrate is adjacent to a second mold compound.

In eighteenth examples, for any of the sixteenth through seventeenth examples, forming the fluid conduit comprises one of forming a vertical channel through at least a partial thickness of the substrate structure by laser drilling through the mold compound.

In nineteenth examples, for any of the sixteenth through eighteenth examples forming the fluid conduit comprises removing, selectively to the mold compound, a sacrificial material from one side of the interconnect trace.

In twentieth examples, for any of the sixteenth through nineteenth examples, the method further comprises coupling a fluid supply to a first end of the fluid conduit, and coupling a fluid return to a second end of the fluid conduit.