INTEGRATED CIRCUIT PACKAGE WITH HEAT TRANSFER CHIMNEY INCLUDING THERMALLY CONDUCTIVE NANOPARTICLES

An electronic device includes an integrated circuit package including a die mounted on a die carrier, a mold structure at least partially encapsulating the mounted die, and a heat transfer chimney formed on the die. The heat transfer chimney extends at least partially through the mold structure to transfer heat away from the die. The heat transfer chimney is formed from a thermally conductive compound including thermally conductive nanoparticles.

TECHNICAL FIELD

The present disclosure relates to integrated circuit (IC) devices, and more particularly to IC packages with a heat transfer chimney including thermally conductive nanoparticles.

BACKGROUND

As integrated circuit devices (semiconductor devices) become smaller and more densely populated, device performance is becoming increasingly limited by thermal constraints. In addition, integrated circuit devices are often susceptible to magnetic fields and ionizing radiation that negatively affect device performance.

There is a need for improved thermal management in IC devices, e.g., to remove heat from heat-generating dies. There is also a need for improved shielding of IC devices from magnetic fields and ionizing radiation, which can damage or affect the performance of IC devices.

SUMMARY

One aspect provides an electronic device including an integrated circuit (IC) package including a die mounted on a die carrier, a mold structure at least partially encapsulating the mounted die, and a heat transfer chimney formed on the die and extending at least partially through the mold structure to transfer heat away from the die. The heat transfer chimney is formed from a thermally conductive compound including thermally conductive nanoparticles.

In some examples, the heat transfer chimney extends through a full thickness of the mold structure, wherein a distal surface of the heat transfer chimney is exposed through an outer surface of the mold structure.

In some examples, the die carrier comprises a lead frame or an interposer.

In some examples, the thermally conductive nanoparticles comprise at least one of diamond nanoparticles, silicon carbide nanoparticles, boron nitride nanoparticles, hexagonal boron nitride nanoparticles, or boron nitride nanotubes.

In some examples, the thermally conductive compound including thermally conductive nanoparticles dispersed in a polymer resin.

In some examples, the thermally conductive compound includes thermally conductive nanoparticles and silica dispersed in an epoxy resin.

In some examples, the mold structure includes magnetic shielding nanoparticles to shield the die from magnetic fields.

In some examples, the magnetic shielding nanoparticles comprise at least one of mu-metal or hematite (Fe2O3).

In some examples, the mold structure includes radiation shielding nanoparticles to shield the die from ionic radiation.

In some examples, the electronic device includes a shielding layer formed over the mold structure, the shielding layer including at least one of (a) magnetic shielding nanoparticles to shield the die from magnetic fields or (b) radiation shielding nanoparticles to shield the die from ionizing radiation.

In some examples, the electronic device includes a multi-layer shield formed over the mold structure, wherein the multi-layer shield includes multiple different shielding layers, wherein respective shielding layers of the multiple different shielding layers include shielding nanoparticles to shield the die from at least one of magnetic fields or ionizing radiation, wherein the multiple different shielding layers include different types or different concentrations of shielding nanoparticles.

In some examples, the different types or different concentrations of shielding nanoparticles in the multiple different shielding layers of the multi-layer shield defines a shielding gradient.

In some examples, the integrated circuit package is mounted on a first side of a package support structure, and the electronic device includes a back-side shielding layer formed on a second side of the package support structure opposite the first side, the back-side shielding layer including shielding nanoparticles to shield the die from at least one of magnetic fields or ionizing radiation.

In some examples, the package support structure comprises a printed circuit board or an interposer.

One aspect provides a method including forming an integrated circuit package, including mounting a die on a die carrier, forming a heat transfer chimney on the die, and forming a mold structure at least partially encapsulating the die, wherein the heat transfer chimney extends at least partially through the mold structure, and wherein the heat transfer chimney includes thermally conductive nanoparticles to transfer heat away from the die.

In some examples, the method includes forming a thermally conductive compound, including mixing (a) silica particles and (b) thermally conductive nanoparticles with a polymer, and forming the heat transfer chimney from the thermally conductive compound.

In some examples, the method includes forming a thermally conductive compound, including (a) mixing a surfactant with the thermally conductive nanoparticles to form surfactant-coated thermally conductive nanoparticles, and (b) mixing the surfactant-coated thermally conductive nanoparticles with a polymer, and forming the heat transfer chimney from the thermally conductive compound.

In some examples, the method includes forming a thermally conductive compound, including (a) mixing a surfactant with the thermally conductive nanoparticles to form surfactant-coated thermally conductive nanoparticles, and (b) mixing (i) the surfactant-coated thermally conductive nanoparticles and (ii) silica filler with an epoxy, and forming the heat transfer chimney from the thermally conductive compound.

In some examples, forming the thermally conductive compound includes mixing silica particles and thermally conductive nanoparticles with an epoxy resin, wherein the thermally conductive nanoparticles comprise diamond nanoparticles, silicon carbide nanoparticles, boron nitride nanoparticles, hexagonal boron nitride nanoparticles, or boron nitride nanotubes

In some examples, forming the heat transfer chimney on the die comprises printing the heat transfer chimney using an additive printing process.

In some examples, the method includes mixing shielding nanoparticles with a mold compound to form a nanoparticle-enhanced mold compound, and forming the mold structure from the nanoparticle-enhanced mold compound.

In some examples, the method includes forming a shielding layer over the mold structure, the shielding layer including at least one of (a) magnetic shielding nanoparticles to shield the die from magnetic fields or (b) radiation shielding nanoparticles to shield the die from ionizing radiation.

In some examples, the method includes forming multiple different shielding layers over the mold structure, wherein respective shielding layers of the multiple different shielding layers include shielding nanoparticles to shield the die from at least one of magnetic fields or ionizing radiation, wherein the multiple different shielding layers include different types or different concentrations of shielding nanoparticles.

One aspect provides a method including forming a first integrated circuit package including mounting a first integrated circuit die, and forming a mold structure at least partially encapsulating the first integrated circuit die, and performing a thermal analysis of the first integrated circuit package. The method further includes forming a second integrated circuit package, including determining a first chimney location based on the thermal analysis of the first integrated circuit package, and forming a first heat transfer chimney on a second integrated circuit die at the determined first chimney location.

In some examples, the method further includes performing a thermal analysis of the second integrated circuit package, and forming a third integrated circuit package, including determining a second chimney location, different than the first chimney location, based on the thermal analysis of the second integrated circuit package, and forming a second heat transfer chimney on a third integrated circuit die at the determined second chimney location.

It should be understood the reference number for any illustrated element that appears in multiple different figures has the same meaning across the multiple figures, and the mention or discussion herein of any illustrated element in the context of any particular figure also applies to each other figure, if any, in which that same illustrated element is shown.

DETAILED DESCRIPTION

The present disclosure provides an IC package including a heat transfer chimney formed from a thermally conductive compound including thermally conductive nanoparticles, for example diamond nanoparticles, silicon carbide (SiC) nanoparticles, boron nitride (BN) nanoparticles, hexagonal boron nitride (h-BN) nanoparticles, or boron nitride nanotubes (BNNT), to improve thermal management of the respective IC packages. In some examples the heat transfer chimney may be formed by an additive printing process, e.g., a 2D, 2.5D, or 3D printing process. The heat transfer chimney including thermally conductive nanoparticles may improve heat transfer from a die, which may lower an operating temperature of the die, decrease dark silicon, increase battery life, or otherwise improve performance of the respective IC package.

Some examples also include shielding nanoparticles, e.g., for shielding a die (or multiple dies) from magnetic fields and/or ionizing radiation, provided in a mold encapsulation formed over the die(s) and/or provided in additional shielding layers formed over the mold encapsulation. For example, IC devices incorporating radiation shielding nanoparticles may be provided for Low Earth Orbit (LEO) applications that require or benefit from improved radiation shielding. As another example, magnetically susceptible products (for example magneto-resistive random-access memory (MRAM) or a chip scale atomic clock may benefit from a high permeability magnetic shield.

FIG.1is a cross-sectional side view showing an example integrated circuit package100including a die102mounted on a die carrier104, a heat transfer chimney110formed on the die102, and a mold structure106(e.g., a mold encapsulation) at least partially encapsulating the mounted die102. The heat transfer chimney110may extend at least partially through the mold structure106to transfer heat away from the die102. The heat transfer chimney110may be formed from a thermally conductive compound112including thermally conductive nanoparticles114. In some examples the heat transfer chimney110extends through a full thickness of the mold structure106, such that a distal surface118of the heat transfer chimney110is exposed through an outer surface108of the mold structure106.

The die102may comprise any type of die, chip (e.g., silicon substrate having an integrated circuit formed thereon), or other integrated circuit device (e.g., including analog devices, digital devices, or a mixture of analog and digital devices) that generates or outputs heat. For example, the die102may comprise a microprocessor (e.g., a central processing unit (CPU) chip), a microcontroller (MCU), an application specific IC (ASIC), a graphics processing unit (GPU), a digital signal processor (DSP), an A/D converters or D/A converter, or memory (e.g., Flash memory, random access memory (RAM), read only memory (ROM), e.g., electrically erasable programmable read-only memory (EEPROM), or other memory), or a system-on-chip (SoC) device.

The die carrier104may comprise any structure on which the die102may be mounted, for example a printed circuit board (PCB), a lead frame, an interposer, a heat sink, or another die. The die102may be mounted on the die carrier104in any suitable manner, for example solder mounting, adhesive bonding (e.g., using an epoxy), flip-chip bonding, or eutectic bonding.

As indicated above, the heat transfer chimney110formed on the die102may be formed from a thermally conductive compound112including thermally conductive nanoparticles114, and functions to transfer heat away from the die102.

In some examples the thermally conductive compound112includes thermally conductive nanoparticles114dispersed in a polymer base, for example an epoxy resin. In some examples the thermally conductive compound112includes thermally conductive nanoparticles114dispersed in or otherwise combined with a base compound116, for example a polymer resin. In some examples the thermally conductive compound112also includes silica (SiO2) filler (e.g., in the form of fumed silica or colloidal silica) to thicken or otherwise enhance the structural integrity of the base compound (e.g., epoxy)116. Thus, the thermally conductive compound112may include thermally conductive nanoparticles114and silica (SiO2) filler dispersed in or otherwise combined with an epoxy resin. As used herein, a “compound” may refer to one element or substance, or a mixture or other combination of multiple elements or substances. The term nanoparticles, as used herein, refers to a particle having a maximum dimension between 1 and 100 nanometers.

In some examples the thermally conductive nanoparticles114comprise at least one of diamond nanoparticles, silicon carbide (SiC) nanoparticles, boron nitride (BN) nanoparticles, hexagonal boron nitride (h-BN) nanoparticles, or boron nitride nanotubes (BNNT). In some examples, the thermally conductive compound112includes a mixture of thermally conductive nanoparticles114and a base compound116comprising an epoxy resin or a mixture of epoxy resin and silica (SiO2).

The heat transfer chimney110may be formed on the die102in any suitable manner. In some examples the heat transfer chimney110may be printed on the die102using an additive printing process, for example a 2D, 2.5D, or 3D printing process. In such examples, the horizontal lines shown in the heat transfer chimney110(in all figures) may represent printed layers of the thermally conductive compound112. In other examples, the heat transfer chimney110may be formed by injection molding using a nozzle (e.g., using a microliter/minute flow rate), or spin-coating. In some examples the heat transfer chimney110may be formed on the die102at a selected location or area of the die102, for example a heat-generating area of the die102(e.g., as determined based on a thermal analysis, as discussed below with reference toFIG.10).

In some examples, the mold structure106may also include performance-enhancing nanoparticles. For example, the mold structure106may comprise a nanoparticle-enhanced mold compound120including shielding nanoparticles122dispersed in or otherwise combined with a base mold compound124. The base mold compound124may comprise, for example, an elastomer (e.g., silicone, polyurethane, chloroprene, butyl, polybutadiene, neoprene, natural rubber or isoprene), a thermoset (e.g., thermoset resin), or other molding compound, which may be supplied in the form of pellets, liquids, or powders, for example. In some examples the shielding nanoparticles122may include nanoparticles to shield the die102from magnetic fields and/or ionizing radiation. For example, the shielding nanoparticles122may include magnetic shielding nanoparticles to shield the die from magnetic fields. Magnetic shielding nanoparticles may include mu-metal or hematite (Fe2O3) nanoparticles, for example. As another example, the shielding nanoparticles122may include radiation shielding nanoparticles to shield the die from ionizing radiation. Radiation shielding nanoparticles may include, for example, boron nitride (BN), bismuth (Bi), bismuth oxide (Bi2O3), tantalum nitride (TaN), tungsten nitride (W3N2), tin oxide (SnO2), copper (I) oxide (Cu2O) (i.e., cuprous oxide), or copper (II) oxide (CuO) (i.e., cupric oxide) nanoparticles.

In some examples, the example integrated circuit package100may optionally include at least one shielding layer130formed over the mold structure106. The illustrated example shows two example shielding layers132and134formed over the mold structure106, with shielding layer134formed over shielding layer132. Other examples include a single shielding layer130, or more than two shielding layers130(e.g., three, four, or more shielding layers130). Other examples omit shielding layers130. Respective shielding layer(s)130may include shielding nanoparticles dispersed in or otherwise combined with a base. For example, respective shielding layer(s)130may include magnetic shielding nanoparticles and/or radiation shielding nanoparticles, e.g., as discussed above regarding mold structure106.

In examples with multiple shielding layers130, different shielding layers130may include different types or different concentrations of shielding nanoparticles. For example, referring to the example shown inFIG.1, shielding layer132may comprise magnetic shielding nanoparticles (e.g., to shield die102from magnetic fields) and shielding layer134may comprise radiation shielding nanoparticles (e.g., to shield die102from ionic radiation). As another example, shielding layers132and134may comprise the same type of nanoparticles (e.g., magnetic shielding nanoparticles or radiation shielding nanoparticles) but with a respective different concentration of nanoparticles, to thereby define a shielding gradient along a direction toward or away from the die102. For example, the shielding layers132and134may provide an increasing degree of shielding in a direction toward the die102(e.g., wherein the shielding layer132, which may be termed inner shielding layer132, may provide a greater degree of shielding than shielding layer134, which may be termed outer shielding layer134).

In examples including at least one shielding layer130, the heat transfer chimney110may extend through the shielding layer(s)130, as indicated by110′ inFIG.1. In other examples, the shielding layer(s)130may cover the distal surface118of the heat transfer chimney110.

FIGS.2A-2Fshow an example process for forming the example integrated circuit package100shown inFIG.1.

FIG.2Ais a cross-sectional side view showing a die102mounted on die carrier104using any suitable mounting technique, for example solder mounting, adhesive bonding (e.g., using an epoxy), flip-chip bonding, or eutectic bonding.

As shown inFIG.2B, the thermally conductive compound112is formed. In this example, (a) thermally conductive nanoparticles114(e.g., comprising diamond nanoparticles, silicon carbide (SiC) nanoparticles, boron nitride (BN) nanoparticles, hexagonal boron nitride (h-BN) nanoparticles, or boron nitride nanotubes (BNNT)) and (b) (optional) silica (SiO2) filler115(e.g., in the form of fumed silica or colloidal silica) are mixed or otherwise combined with (c) a base compound116(e.g., comprising an epoxy resin or other polymer) to produce the thermally conductive compound112. The thermally conductive nanoparticles114, (optional) silica filler115, and base compound116may be mixed or combined in any suitable manner, for example using an agitation and/or ultrasonic vibration process.

In some examples a surfactant113may (optionally) be added to enhance or expedite the dissolving of the thermally conductive nanoparticles114in the base compound (e.g., epoxy)116. For example, the thermally conductive nanoparticles114may be mixed with a surfactant that forms a coating on the respective thermally conductive nanoparticles114(e.g., after waiting several hours), and the resulting surfactant-coated nanoparticles114and silica filler115may be mixed (e.g., by an agitation or ultrasonic vibration process) with an epoxy base116. In some examples, the surfactant113may include one or more long-chain amphiphilic compounds including both hydrophobic and hydrophilic groups, wherein such compound(s) may be classified according based on a subtype of the hydrophilic group, e.g., cationic, anionic, zwitterionic, or nonionic surfactants.

In some examples, the thermally conductive nanoparticles114(with or without surfactant coating) and silica filler115may be added to the base compound116(e.g., epoxy resin) in a single step. For example, the thermally conductive nanoparticles114may first be mixed with silica filler115, and then dispersed in an epoxy resin. In other examples, silica filler115may first be added to the base compound116(e.g., epoxy resin) to form a base compound/silica mixture, and the thermally conductive nanoparticles114may then be dispersed in the base compound/silica mixture.

The thermally conductive nanoparticles114and the (optional) silica filler115may comprise any suitable portion, e.g., as defined by volume fraction, of the resulting thermally conductive compound112. In some examples using an epoxy as the base compound116, the thermally conductive nanoparticles114and the (optional) silica filler115may collectively define up to 85% by volume fraction of the resulting thermally conductive compound112, which may provide a sufficient amount of epoxy (e.g., at least 15% by volume fraction) for structural integrity of a heat transfer chimney110formed from the thermally conductive compound112. In some examples, the thermally conductive nanoparticles114may comprise 5-85% by volume fraction of the thermally conductive compound112. In certain examples, the thermally conductive nanoparticles114may comprise 50-75% by volume fraction of the thermally conductive compound112.

As shown inFIG.2C, the heat transfer chimney110is formed on the die102from the thermally conductive compound112. In some examples the heat transfer chimney110is printed on the die102using an additive printing process, for example a 2D, 2.5D, or 3D printer. For example, the heat transfer chimney110may be printed in a single layer or multiple layers (e.g., 2-20 layers). In some examples the heat transfer chimney110may be formed by depositing a single droplet or a small number of droplets using a 2D printer, e.g., a 2D nozzle-based inkjet printer. In some examples, the 2.5D or 3D printer may include, for example, a resin dispense printer, a 2D inkjet printer or other 2D fluid dispense printer (e.g., configured to deposit droplets through a single nozzle or pattern of nozzles), a 2.5D fluid dispense printer (e.g., SmartDispenser® General Fluids Benchtop Automation with AirFree® Technology by Fishman Corporation of Hopkinton, Mass.), or a 3D top-down printer (e.g., DM400A DLP 3D printer by Carima, of Seoul, Korea).

In other examples, the heat transfer chimney110may be formed on the die102using an injection molding process, e.g., using an injection molding nozzle to deposit a single droplet or a few droplets of the thermally conductive compound112.

In some examples the heat transfer chimney110may be formed on the die102at a selected location or area of the die102, for example a heat-generating area of the die102. In some examples a thermal analysis may be performed to identify a location on the die102to form the heat transfer chimney110. As discussed below with reference toFIG.10, such thermal analysis may include an iterative process of forming and analyzing heat transfer chimneys at different locations on respective test devices to determine a target location for the heat transfer chimney110.

As shown inFIG.2D, the nanoparticle-enhanced mold compound120is formed. In this example, shielding nanoparticles122are dispersed in or otherwise combined with a base mold compound124to produce the nanoparticle-enhanced mold compound120. In some examples a surfactant113may (optionally) be added to enhance or expedite the dissolving of the shielding nanoparticles122in the base mold compound124, e.g., as discussed above regarding the thermally conductive nanoparticles114dissolved in the base compound116.

The shielding nanoparticles122(with or without surfactant coating) may be mixed or combined with the base mold compound124in any suitable manner, e.g., using an agitation or ultrasonic vibration process. As discussed above, in some examples the shielding nanoparticles122may include magnetic shielding nanoparticles to shield the die102from magnetic fields and/or radiation shielding nanoparticles to shield the die102from ionizing radiation. Example shielding nanoparticles122(including example magnetic shielding nanoparticles and example radiation shielding nanoparticles) and examples of base mold compound124, are listed above with reference toFIG.1.

As shown inFIG.2E, the mold structure106may be formed over the die102from the nanoparticle-enhanced mold compound120. The mold structure106may be formed in any suitable manner, for example by injection molding, compression molding, reaction injection molding (RIM), resin transfer molding (RTM), or blow molding. In some examples the mold structure106may encapsulate exposed surfaces of the die102, e.g., so that the die102is fully encapsulated by the support structure104, mold structure106, heat transfer chimney110, and/or other structures formed on or adjacent the die102. The heat transfer chimney110may extend through the formed mold structure106, so that the distal surface118of heat transfer chimney110is exposed through the mold structure106. For example, the distal surface118of heat transfer chimney110is flush with or projects above the adjacent top surface108of the mold structure106, e.g., allowing a heat sink or other thermally conductive structure to be arranged in direct contact with the heat transfer chimney110for transferring heat away from die102.

In examples in which optional shielding layer(s)130are subsequently formed over the mold structure106(e.g., as shown inFIG.2Fdiscussed below), the heat transfer chimney110and mold structure106may be formed such that heat transfer chimney110extends beyond (in the illustrated example, above) the top surface108of the mold structure106by a distance associated with a total thickness of the shielding layer(s)130, as indicated by110′ inFIG.2F. In such example the top surface118of the heat transfer chimney110′ may be flush with or protrude above a top surface of the outer shielding layer130, as discussed below.

As shown inFIG.2F, in some examples at least one shielding layer130may (optionally) be formed over the mold structure106. The illustrated example shows example shielding layers132and134formed over the mold structure106. As discussed above, respective shielding layers132and134may include shielding nanoparticles (e.g., magnetic shielding nanoparticles and/or radiation shielding nanoparticles) dispersed in or otherwise combined with a base compound, e.g., an epoxy or other polymer. Example magnetic shielding nanoparticles and example radiation shielding nanoparticles are listed above with reference toFIG.1. As discussed above, other examples may include a single shielding layer130, or more than two shielding layers130, or may omit shielding layers130.

In examples including at least one shielding layer130, the heat transfer chimney110may extend through the shielding layer(s)130, as indicated by110′ inFIG.2F. In other examples, the shielding layer(s)130may cover distal surface118(seeFIG.2E) of the heat transfer chimney110.

FIG.3is a cross-sectional side view showing an example IC package300formed as a lead frame package including a die102mounted on a lead frame304. The lead frame304may include a die attach pad306on which the die102is mounted, and a plurality of lead fingers308arranged around a periphery of the die attach pad306. The die102may be mounted on the die attach pad306in any suitable manner, e.g., using an epoxy or other adhesive. The die102may be electrically connected to selected lead fingers308by a number of wire bond wires314soldered or otherwise secured to the die102and to the respective lead fingers308.

As shown, a heat transfer chimney110may be formed on the die102at a selected location or area of the die102using any suitable process, e.g., using an additive printing process (for example a 2D, 2.5D, or 3D printer) or other process disclosed herein. The heat transfer chimney110may be formed from a thermally conductive compound112including thermally conductive nanoparticles114dispersed in a base compound116(e.g., epoxy resin), e.g., as described above. The die102may be encapsulated by a mold structure106, which may extend above and below the die102and die attach pad306. As shown, the mold structure106may be formed such that the distal surface118of the heat transfer chimney110extends through the top surface108of the mold structure106. In other examples the mold structure106may extend over the top of the heat transfer chimney110to thereby encapsulate the heat transfer chimney110.

In some examples, the mold structure106may include shielding nanoparticles dispersed in or otherwise combined with a base mold compound, e.g., as discussed above regardingFIG.1. For example, the shielding nanoparticles may include magnetic shielding nanoparticles to shield the die102from magnetic fields and/or radiation shielding nanoparticles to shield the die102from ionizing radiation. Example magnetic shielding nanoparticles and example radiation shielding nanoparticles are listed above.

FIG.4is a cross-sectional side view showing an example IC package400formed as a ball grid array (BGA) package. The example BGA package400includes a die102mounted on a substrate404(e.g., a B-T epoxy substrate). The die102may be mounted face-up on a die pad406formed on a top side of the substrate404. The die102may be connected to circuitry formed on, or in, the substrate by respective wire bond wires408. Solder balls410may be formed on a bottom side of the substrate404for mounting the IC package400to a PCB or other structure.

As shown, a heat transfer chimney110may be formed on the die102at a selected location or area of the die102using any suitable process, e.g., using an additive printing process (for example a 2D, 2.5D, or 3D printer) or other process disclosed herein. The heat transfer chimney110may be formed from a thermally conductive compound112including thermally conductive nanoparticles dispersed in a base compound (e.g., epoxy resin), e.g., as described above. The die102may be encapsulated by a mold structure106formed over the substrate404. As shown, the mold structure106may be formed such that the distal surface118of the heat transfer chimney110extends through the top surface108of the mold structure106. In other examples the mold structure106may extend over the top of the heat transfer chimney110to thereby encapsulate the heat transfer chimney110.

In some examples, the mold structure106may include shielding nanoparticles dispersed in or otherwise combined with a base mold compound, e.g., as discussed above regardingFIG.1. For example, the shielding nanoparticles may include magnetic shielding nanoparticles to shield the die102from magnetic fields and/or radiation shielding nanoparticles to shield the die102from ionizing radiation. Example magnetic shielding nanoparticles and example radiation shielding nanoparticles are listed above.

FIG.5is a cross-sectional side view showing an example IC package500formed as a flip-chip pBGA (FC-PBGA) package. The example flip-chip PBGA package500includes a die102flip-chip mounted on a substrate504by solder ball mounting with an epoxy underfill506. Solder balls510may be formed on a bottom side of the substrate504for mounting the IC package500to a PCB or other structure.

As shown, a heat transfer chimney110may be formed on the (flip-chip mounted) die102at a selected location or area of the die102using any suitable process, e.g., using an additive printing process (for example a 2D, 2.5D, or 3D printer) or other process disclosed herein. The heat transfer chimney110may be formed from a thermally conductive compound112including thermally conductive nanoparticles dispersed in a base compound (e.g., epoxy resin), e.g., as described above. The die102may be encapsulated by a mold structure106formed over the substrate504. As shown, the mold structure106may be formed such that the distal surface118of the heat transfer chimney110extends through the top surface108of the mold structure106. In other examples the mold structure106may extend over the top of the heat transfer chimney110to thereby encapsulate the heat transfer chimney110. In some examples, the mold structure106may include shielding nanoparticles, e.g., magnetic shielding nanoparticles and/or radiation shielding nanoparticles, as discussed above.

FIG.6is a cross-sectional side view showing an example IC package600including a first die102aand a second die102b, e.g., a field programmable gate array (FPGA) and a power management IC (PMIC), mounted on an interposer604. A first heat transfer chimney110ais formed on the first die102a, and a second heat transfer chimney110bis formed on the second die102b. Heat transfer chimneys110aand110bmay be respectively formed at identified heat-generating locations on the respective dies102aand102b, e.g., as determined based on thermal analysis of IC package600(or similar IC packages).

In the illustrated example, a radiation shielding layer (or encapsulation structure)612is formed over the second die102b(e.g., PMIC die), but not over the FPGA die, to shield the second die102bfrom ionizing radiation. The radiation shielding layer612may include radiation shielding nanoparticles, e.g., boron nitride (BN), bismuth (Bi), bismuth oxide (Bi2O3), tantalum nitride (TaN), tungsten nitride (W3N2), tin oxide (SnO2), copper (I) oxide (Cu2O), or copper (II) oxide (CuO) nanoparticles. A mold compound620is formed over both dies102aand102b, and over the radiation shielding layer612formed over the second die102b. In some examples the mold compound620may include magnetic shielding nanoparticles, e.g., mu-metal or Fe2O3nanoparticles, to shield both the first die102aand the second die102bfrom magnetic fields.

FIG.7is a cross-sectional side view showing an example electronic device700including the example IC package300(lead frame package) shown inFIG.3mounted on a package support structure, e.g., a PCB702. As discussed above with respect toFIG.3, the example lead frame package300includes a lead frame304including a die attach pad306and a plurality of lead fingers308, a die102mounted on the die attach pad306and connected to selected lead fingers308by respective wire bond wires314, a heat transfer chimney110formed on the die102, and a mold structure106extending above and below the die attach pad306and encapsulating the die102. As discussed above, the heat transfer chimney110may be formed from a thermally conductive compound112including thermally conductive nanoparticles114dispersed in a base compound116(e.g., epoxy resin). In addition, the mold structure106may include shielding nanoparticles, for example magnetic shielding nanoparticles to shield the die102from magnetic fields and/or radiation shielding nanoparticles to shield the die102from ionizing radiation.

As shown inFIG.7, the example electronic device700includes upper shielding layers720on a top side of the PCB702and lower shielding layers730on a back side of the PCB702. In the illustrated example, the upper shielding layers720include a first upper shielding layer722formed over the lead frame package300, and a second upper shielding layer724formed over the first upper shielding layer722. The respective upper shielding layers722and724may include shielding nanoparticles (e.g., magnetic shielding nanoparticles and/or radiation shielding nanoparticles) dispersed in or otherwise combined with a base compound, e.g., an epoxy or other polymer. Example magnetic shielding nanoparticles and example radiation shielding nanoparticles are listed above with reference toFIG.1.

In some examples upper shielding layers722and724may include different types or different concentrations of shielding nanoparticles. For example, upper shielding layer722may comprise magnetic shielding nanoparticles (e.g., to shield die102from magnetic fields) and upper shielding layer724may comprise radiation shielding nanoparticles (e.g., to shield die102from ionic radiation), or vice versa. As another example, upper shielding layers722and724may comprise the same type of nanoparticles (e.g., magnetic shielding nanoparticles or radiation shielding nanoparticles) but with a respective different concentration of nanoparticles, to thereby define a shielding gradient along a direction toward, or away from, the die102. For example, upper shielding layers722and724may provide an increasing degree of shielding in a direction toward the die102(e.g., wherein the upper shielding layer722provide a greater degree of shielding than the upper shielding layer724).

Similarly, the lower shielding layers732and734may include shielding nanoparticles (e.g., magnetic shielding nanoparticles and/or radiation shielding nanoparticles) dispersed in or otherwise combined with a base compound, e.g., an epoxy or other polymer. Like the upper shielding layers722and724, the lower shielding layers732and734may include different types or different concentrations of shielding nanoparticles, e.g., which may define a shielding gradient.

FIG.8is a cross-sectional side view showing an example electronic device800including a first (lower) die802aand a second (upper) die802barranged on a PCB804in a stacked manner and separated from each other by an insulating layer806, wherein the second (upper) die802bgenerates more heat than the first (lower) die802a. A heat transfer chimney810is formed over both dies802aand802bto remove heat generated by both dies802aand802b. As shown, the heat transfer chimney810may cover a larger area of the second die802bthan the first die802a, in order to provide additional heat transfer from the hotter second die802b. For example, (b) an area of contact between the heat transfer chimney810and the second die802band (b) an area of contact between the heat transfer chimney810and the first die802amay be proportional to, or otherwise correspond with, a relationship between the heat generated by the second die802bas compared with the first die802a.

In some examples the heat transfer chimney810formed on dies802aand802bmay comprise a single droplet or a few droplets of a thermally conductive compound112, e.g., formed by a 2D, 2.5D, or 3D printer or nozzle-based injection molding, e.g., as discussed above. Forming a single heat transfer chimney on multiple dies may provide cost savings as compared with forming a distinct heat transfer chimney on the respective dies, and may allow for a more compact design, e.g., using a smaller footprint.

As shown inFIG.8, a mold structure812may be formed over the first and second dies802aand802b. A heat sink820may be formed over the mold structure812and thermally coupled to the heat transfer chimney810, to facilitate heat transfer away from the second die802b.

FIG.9is a flowchart showing an example method900for forming an integrated circuit package. At902, a die is mounted on a die carrier. At904, thermally conductive nanoparticles and (optionally) silica particles are mixed with a polymer base (e.g., epoxy resin) to form a thermally conductive compound. At906, the thermally conductive compound is used to form a heat transfer chimney on the die, e.g., using a 2D, 2.5D, or 3D printer to print the heat transfer chimney. At908, a mold structure if formed, which at least partially encapsulates the die. In some examples the mold structure may include shielding nanoparticles (e.g., magnetic shielding nanoparticles and/or radiation shielding nanoparticles), e.g., as discussed above.

FIG.10is a flowchart showing an example method1000for analyzing and adjusting a location of a heat transfer chimney. At1002a first IC package including a first IC die mounted on a first die carrier, and a mold structure is formed over the mounted first IC die. A thermal analysis of the first IC package, in operation, is performed at1004, e.g., performing a thermal scan of the first IC package using an infrared (IR) camera. At1006, a first chimney location is determined based on the thermal analysis of the first IC package. For example, a thermal tensor flow module may analyze a thermal scan performed at1004and generate a thermal model to identify a first location for forming a heat transfer chimney. At1008, a second IC package is formed, including a first heat transfer chimney on a second IC die (e.g., using an additive printing process) at the determined first chimney location. The second IC die is a second instance of the first IC die.

A thermal analysis of the second IC package is, in operation, performed at1010, e.g., performing a thermal scan of the second IC package using an infrared (IR) camera. At1012, a second chimney location (e.g., different than the first chimney location) is determined based on the thermal analysis of the second IC package, e.g., using a thermal tensor flow module to analyze a thermal scan performed at1010and generate a thermal model to identify a second location for forming a heat transfer chimney. At1014, a third IC package is formed, including a second heat transfer chimney is formed on a third IC die (e.g., using an additive printing process) at the determined second chimney location. The third IC die is a third instance of the first IC die. This process may continue, e.g., in an iterative manner, to identify a target location of the heat transfer chimney for improved thermal performance.