Patent Publication Number: US-2021193549-A1

Title: Package wrap-around heat spreader

Description:
TECHNICAL FIELD 
     Embodiments of the present disclosure relate to semiconductor devices, and more particularly to wrap-around heat spreaders to provide improved thermal control of multi-die packages. 
     BACKGROUND 
     Higher performance, lower cost, and greater packaging density of integrated circuits are ongoing goals of the microelectronic industry. To achieve these goals, microelectronic devices are continuously miniaturized and/or stacked in 3D architectures. While 3D architectures allow for improved density, thermal management becomes a significant challenge for such devices due to the high power density of the components, the compounding impact of hot spots from multiple dies, and the high thermal resistance usually experienced by the bottom dies. Thermal management is a critical concern for 3D packages, because the integrated circuits in those devices may be damaged or destroyed if the temperature of the microelectronic device raises too high. 
     However, existing thermal solutions, such as an integrated heat spreader (IHS) that interfaces with only the top dies, do not provided the needed cooling for the bottom dies in a stack. For example, the primary thermal path from the bottom die in a multi-die stack to the IHS passes through low thermal conductivity layers such as underfill or mold compound. Similarly, in double sided systems (i.e., with a die module both above and below the package substrate), the primary thermal path from the bottom die module to the IHS passes through the package substrate. 
     Underfills, mold compounds, and package substrates are predominantly made of organic materials, and improvements to thermal conductivity of organic materials are severely limited by material properties. Additionally, attempts to reduce thermal resistance by improving the performance of the thermal interface material (TIM) or underfills only provides incremental improvements. Such incremental improvements do not scale with future generations as the power dissipated by the dies continues to increase. In the case of a double sided system, a second thermal solution (e.g., a second IHS) for the bottom die is not always possible due to cost and size limitations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a cross-sectional illustration of an electronic package with a wrap-around heat spreader (WAHS), in accordance with an embodiment. 
         FIG. 1B  is a cross-sectional illustration of an electronic package for accommodating die modules on two surfaces that includes a WAHS, in accordance with an embodiment. 
         FIG. 1C  is a cross-sectional illustration of an electronic package with a WAHS that includes thermal slugs embedded in the package substrate, in accordance with an embodiment. 
         FIG. 1D  is a cross-sectional illustration of an electronic package with a WAHS that includes components embedded in the package substrate that are thermally coupled to the WAHS, in accordance with an embodiment. 
         FIG. 2A  is a cross-sectional illustration of an edge of the electronic package that more clearly illustrates a WAHS that is spaced away from the sidewall of the package substrate, in accordance with an embodiment. 
         FIG. 2B  is a cross-sectional illustration of an edge of the electronic package that more clearly illustrates a WAHS that is secured to the sidewall of the package substrate, in accordance with an embodiment. 
         FIG. 3A  is a plan view illustration of a top surface of an electronic package that comprises a pair of WAHSs, in accordance with an embodiment. 
         FIG. 3B  is a plan view illustration of a top surface of an electronic package that comprises a plurality of WAHSs, in accordance with an additional embodiment. 
         FIG. 4A  is a cross-sectional illustration of an electronic package with a 3D die stack and a WAHS, in accordance with an embodiment. 
         FIG. 4B  is a cross-sectional illustration of an electronic package with a 3D die stack and an embedded component that is thermally coupled to a WAHS, in accordance with an embodiment. 
         FIG. 4C  is a cross-sectional illustration of an electronic package with a first die module and a second die module on an opposite surface, where the second die module is thermally coupled to a WAHS, in accordance with an embodiment. 
         FIG. 4D  is a plan view illustration of a bottom surface of an electronic package with a WAHS, in accordance with an embodiment. 
         FIG. 5  is a cross-sectional illustration of an electronic system that includes an electronic package with a WAHS, in accordance with an embodiment. 
         FIG. 6  is a schematic of a computing device built in accordance with an embodiment. 
     
    
    
     EMBODIMENTS OF THE PRESENT DISCLOSURE 
     Described herein are electronic packages with wrap-around heat spreaders to provide improved thermal control of multi-die packages, in accordance with various embodiments. In the following description, various aspects of the illustrative implementations will be described using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that the present invention may be practiced with only some of the described aspects. For purposes of explanation, specific numbers, materials and configurations are set forth in order to provide a thorough understanding of the illustrative implementations. However, it will be apparent to one skilled in the art that the present invention may be practiced without the specific details. In other instances, well-known features are omitted or simplified in order not to obscure the illustrative implementations. 
     Various operations will be described as multiple discrete operations, in turn, in a manner that is most helpful in understanding the present invention, however, the order of description should not be construed to imply that these operations are necessarily order dependent. In particular, these operations need not be performed in the order of presentation. 
     As noted above, thermal management of 3D packaging architectures is limited by layers or components such as underfills, mold compounds, or package substrates that have a low thermal conductivity. Accordingly, heat is not easily propagated from the bottom dies to the integrated heat spreader (IHS). Therefore, embodiments disclosed herein include thermal solutions that provide high thermal conductivity paths from the bottom dies to the IHS. 
     In a particular embodiment, the high thermal conductivity path includes a flexible heat spreader that wraps around the package substrate. Such a heat spreader may be referred to as a wrap-around heat spreader (WAHS). A first portion of the WAHS may be secured to the top surface of the package substrate and a second portion of the WAHS may be secured to the bottom surface of the package substrate. A third portion of the WAHS wraps along the sidewall of the package substrate to connect the first portion of the WAHS to the second portion of the WAHS. In an embodiment, supports of the IHS are secured to the first portion of the WAHS. 
     In an embodiment, the WAHS has high in-plane thermal conductivity. For example, the WAHS may comprise graphene or high conductivity graphite sheets, a heat pipe, a vapor chamber, or the like. In some embodiments, thermal features (e.g., vias, thermal slugs, etc.) that pass through a thickness of the package substrate may thermally couple the bottom dies to the WAHS. Accordingly, a high thermal conductivity path from the bottom dies to the IHS is provided. 
     In some embodiments, the electronic package comprises a first die module on a top surface of the package substrate and a second die module on the bottom surface of the package substrate. In such embodiments, the WAHS provides a high thermal conductivity path from the bottom die module to the IHS. As such, there is no need for a second thermal solution dedicated to the bottom die module. 
     Referring now to  FIG. 1A , a cross-sectional illustration of an electronic package  100  is shown, in accordance with an embodiment. In  FIG. 1A , a die module  140  and an integrated heat spreader (IHS)  150  are illustrated with dashed lines to indicate that any suitable die module  140  or IHS  150  may be integrated with the electronic package  100 . More detailed descriptions of the die module  140  and the IHS  150  are provided below. 
     In an embodiment, the electronic package  100  comprises a package substrate  110 . The package substrate may be an organic package substrate. The package substrate  110  may comprise a plurality of layers laminated over each other. For example, the package substrate  110  may comprise a plurality of layers of buildup film (BF), or the like. In an embodiment, the package substrate  110  may comprise conductive features (e.g., traces, vias, etc.) for routing electrical paths from a first surface  111  of the package substrate  110  to a second surface  112  of the package substrate  110 . The conductive features for electrical routing are not shown for simplicity. 
     However, thermal routing is shown in the package substrate  110 . For example, one or more thermal vias  115  may pass from the first surface  111  to the second surface  112  of the package substrate. Accordingly, heat generated from the die module  140  may rapidly pass from the first surface  111  to the second surface  112  of the package substrate  110 , despite the low thermal conductivity of the organic material of the package substrate  110 . In an embodiment, the thermal vias  115  are dedicated for thermal purposes. That is, in some embodiments, the thermal vias  115  are not held at any particular voltage. In other embodiments, the thermal vias  115  may be part of a ground plane and, therefore, may be held at a certain voltage. In the illustrated embodiment, the thermal vias  115  are shown as having substantially vertical sidewalls. In other embodiments, the thermal vias  115  may have tapered sidewalls, typical of laser drilling in package manufacturing. Additionally, the thermal vias  115  may include alternating vias and pads through a thickness of the package substrate  110 . 
     In an embodiment, the electronic package  100  may further comprise a WAHS  120 . In an embodiment, the WAHS may comprise a first portion  121  secured to the first surface  111 , a second portion  122  secured to the second surface  112 , and a third portion  123  that wraps along a sidewall surface  113  of the package substrate  110 . In an embodiment, the first portion  121  may be secured to the first surface  111  with a sealant  132  or other adhesive material. In an embodiment, the second portion  122  is secured to the second surface  112  with a thermal interface material (TIM)  131 . The use of a TIM allows for thermal energy to pass from the thermal vias  115  to the WAHS  120  with minimal thermal resistance. In an embodiment, TIMs disclosed herein may be any suitable TIM materials, such as solder or polymer TIMs, or adhesives with high thermal conductivities (e.g., metal filled epoxies). 
     In an embodiment, the WAHS  120  has a high in-plane thermal conductivity. The high in-plane thermal conductivity allows for thermal energy to easily propagate between the second portion  122  and the first portion  121 . In a particular embodiment, the WAHS  120  comprises a flexible material. The use of a flexible material allows for a monolithic WAHS  120  to wrap over the sidewall  113  between the first portion  121  and the second portion  122 . In an embodiment, the WAHS  120  may comprise graphene or high conductivity graphite sheets, a heat pipe, a vapor chamber, or any combination thereof. 
     In an embodiment, the first portion  121  of the WAHS  120  may be thermally coupled to the IHS  150 . Particularly, supports  152  extending down from a main body  151  are coupled to the first portion  121  of the WAHS  120 . For example, a TIM  133  may be between the supports  152  and the first portion  121  of the WAHS  120 . Accordingly, a low thermal resistance path from the die module  140  to the IHS  150  is provided. In an embodiment, the primary low thermal resistance path may include the thermal vias  115 , the TIM  131 , the WAHS  120 , the TIM  133 , and the supports  152  of the IHS  150 . Such a low thermal resistance path allows for improved thermal control of the die module  140  since the primary thermal path no longer needs to pass through organic materials such as mold or underfill layers (not shown) in the stack comprising the die module. 
     In an embodiment, a pair of WAHSs  120  are provided along opposing sidewalls  113  of the package substrate  110 . In some embodiments, a single WAHS  120  is provided. In other embodiments, more than two WAHSs  120  may be included, as will be described in greater detail below. 
     In an embodiment, the WAHS  120  may have any suitable dimensions to accommodate the architecture of the electronic package  100 . For example, the WAHS  120  may be routed around interconnects or other components on the surfaces  111  or  112  of the package substrate  110 . In a particular embodiment, a first length L 1  of the first portion  121  may be smaller than a second length L 2  of the second portion  122 . For example, the first length L 1  may be such that the first portion  121  remains outside of a footprint of the die module  140 , and the second length L 2  may be such that the second portion  122  at least partially extends under the footprint of the die module  140 . Extending the second portion  122  under the footprint of the die module  140  allows for the primary thermal path to be substantially vertical through a thickness of the package substrate  110 . That is, horizontal propagation of the thermal energy may be implemented by the WAHS  120  that has superior in-plane thermal conductivity. 
     Referring now to  FIG. 1B , a cross-sectional illustration of an electronic package  100  is shown, in accordance with an additional embodiment. In an embodiment, the electronic package  100  in  FIG. 1B  may be substantially similar to the electronic package  100  in  FIG. 1A , with the exception that a second die module  141  is attached to the second surface  112  of the package substrate  110 . The second die module  141  may be thermally coupled to the WAHS  120 . As such, heat generated by the second die module  141  may be propagated to the IHS  150  over the first surface  111  without needing to pass through a thickness of the package substrate  110 . Therefore, a second thermal solution (e.g., a second IHS) dedicated to the second die module  141  is not needed. This provides a cost and size savings for the electronic package  100 . 
     Referring now to  FIG. 1C , a cross-sectional illustration of an electronic package  100  is shown, in accordance with an embodiment. In an embodiment, the electronic package  100  is substantially similar to the electronic package  100  in  FIG. 1A , with the exception that the thermal vias  115  are augmented by thermal slugs  116 . In an embodiment, one or more thermal slugs  116  may be embedded into the package substrate  110 . The thermal slugs  116  comprise a high thermal conductivity material. In a particular embodiment, the thermal slugs  116  comprise copper or other metallic material. The thermal slugs  116  provide additional thermal mass along the primary thermal path from the die module  140  to the IHS  150 . In an embodiment, the thermal slugs  116  may be thermally coupled to one or more thermal vias  115 . For example, a thermal trace  117  may connect the thermal slug  116  to the thermal via  115 . In an embodiment, the thermal slugs  116  may directly interface with the TIM  131 . The thermal slugs  116  may also increase a surface area of thermally conductive material that interfaces with the TIM  131  and the WAHS  120 . Accordingly, the WAHS  120  is able to extract more thermal energy from the die module  140 . 
     Referring now to  FIG. 1D , a cross-sectional illustration of an electronic package  100  is shown, in accordance with an additional embodiment. The electronic package  100  in  FIG. 1D  may be substantially similar to the electronic package  100  in  FIG. 1C , with the exception that the thermal slugs  116  are thermally coupled to one or more components  161  or  162  embedded in the substrate  110 . 
     In one embodiment, component  161  may be a thermoelectric cooler (TEC). The TEC  161  may be positioned below the die module  140 . A TEC  161  may provide active cooling to the die module  140 . That is, a first surface (facing the die module  140 ) of the TEC  161  may be a cooling surface and a second surface (facing away from the die module  140 ) may be a heating surface. The heating surface may be thermally coupled to the WAHS  120  by a thermal slug  116  or the like. Accordingly, heat generated by the TEC  161  is rapidly removed from the package substrate  110  and propagated to the IHS  150  by the WAHS  120 . 
     In another embodiment, additional components  162  may also be thermally controlled by being thermally coupled to a WAHS  120 . Components  162  may include any discrete component suitable for electronic packaging. For example, the components  162  may be passive components, such as capacitors, voltage regulators, passive bridges, or the like. In an embodiment, the additional components  162  may also comprise active components, such as a die, an active bridge, or the like. 
     Referring now to  FIG. 2A , a cross-sectional illustration that more clearly depicts a structure of a WAHS  220  is shown, in accordance with an embodiment. As shown, the WAHS  220  may have a first portion  221  that is secured to a first surface  211  of a package substrate  210  by a sealant  232  or the like, and a second portion  222  that is secured to a second surface  212  of the package substrate  210  by a TIM  231 . In an embodiment, a third portion  223  of the WAHS  220  attaches the first portion  221  to the second portion  222 . 
     In an embodiment, the WAHS  220  is a monolithic structure. That is, the first portion  221 , the second portion  222 , and the third portion  223  are part of a single monolithic component. For example, the WAHS  220  may be a flexible body that is able to be wrapped around the sidewall  213  of the package substrate  210 . As shown, the WAHS  220  may have curved corners  227  indicative of the WAHS  220  bending. 
     In some embodiments, the WAHS  220  is not secured to the sidewall surface  213  of the package substrate  210 . For example, as shown in  FIG. 2A , the third portion  223  is spaced away from the sidewall  213  by a gap G. In other embodiments, the WAHS  220  may be in direct contact with the sidewall  213 . That is, there may not be a gap G between the third portion  223  and the sidewall  213 . 
     Referring now to  FIG. 2B , a cross-sectional illustration that more clearly depicts an alternative structure of a WAHS  220  is shown, in accordance with an additional embodiment. In an embodiment, the third portion  223  of the WAHS  220  may be secured to the sidewall  213  of the package substrate  210 . For example, a portion of the TIM  231  may wrap around the corner and extend along the sidewall  213 . As such, additional portions of the package substrate  210  may be thermally coupled to the WAHS  220  in order to further improve thermal performance. In other embodiments, the TIM  231  on the sidewall  213  may be replaced with any suitable adhesive. 
     Referring now to  FIG. 3A , a top view illustration of the package substrate  310  is shown, in accordance with an embodiment. In the illustrated view, the first surface  311  of the package substrate  310  is shown. In an embodiment, a pair of WAHSs  320  extend over the first surface  311 . For example, a first WAHS  320 A wraps around the left edge of the package substrate  310  and a second WAHS  320 B wraps around the right edge of the package substrate  310 . As shown, the first portions  321  of the WAHSs  320  extend towards the center of the package substrate  310 . The area of the first portions  321  may be suitable for accepting supports of an IHS (not shown). In the illustrated embodiment, the first WAHS  320 A and the second WAHS  320 B are shown as being on opposite edges of the package substrate  310 . However, it is to be appreciated that WAHSs  320  may be on any of the edges of the package substrate  310 , depending on the routing and thermal requirements of the electronic package. 
     Referring now to  FIG. 3B , a top view illustration of the package substrate  310  is shown, in accordance with an additional embodiment. As shown, the package substrate  310  comprises a plurality of WAHSs  320 A-D. For example, a WAHS  320  is located over each of the four edges of the package substrate. In the illustrated embodiment, each edge of the package substrate  310  comprises a single WAHS  320 . However, in additional embodiments, one or more edges of the package substrate  310  may comprise a plurality of WAHSs  320 , depending on the routing and thermal requirements. 
     Referring now to  FIG. 4A , a cross-sectional illustration of an electronic package  400  is shown, in accordance with an embodiment. In an embodiment, the electronic package  400  may comprise a package substrate  410  and a die module  440  over the package substrate  410 . An IHS  450  may be thermally coupled to a top surface of the die module  440 . For example, a main body  451  of the IHS  450  may be thermally coupled to the top surface of the die module  440  by a TIM  448 . In an embodiment, the IHS  450  may also comprise one or more supports  452  that extend down towards the package substrate  410 . 
     In an embodiment, the die module  440  may comprise a plurality of dies and have a 3D architecture. For example, the illustrated die module  440  may comprise a first die  442 , and a plurality of second dies  443  that are attached to the backside surface of the first die  442  by interconnects  445 . In an embodiment, the second dies  443  may be electrically coupled to the first die  442  by vias (not shown) through the first die  442 . In an embodiment, the second dies  443  may be embedded in a mold layer  446 , such as epoxy. 
     In the illustrated embodiment, a single first die  442  is shown. Alternative embodiments may include a plurality of first dies  442 . For example, a plurality of first dies  442  may be electrically coupled together by a bridge embedded in the package substrate  410 . In an embodiment, the first die  442  is electrically coupled to the package substrate  410  by interconnects  444 . In an embodiment, the interconnects  444  may be surrounded by an underfill  447 . In an embodiment, the underfill  447  may be optimized for thermal performance. For example, the underfill  447  may be an epoxy with high thermal conductivity fillers or the like. 
     3D architectures, such as the one illustrated in  FIG. 4A  provide significant thermal challenges. While the backside surfaces of the second dies  443  are directly connected to the main body  451  of the IHS  450  by the TIM  448 , there is no direct thermal path to the IHS  450  for the bottom first die  442 . Accordingly, embodiments disclosed herein include a primary thermal path that passes through the package substrate  410  and wraps around the sidewall  413  outside of the package substrate  410 , and back to the supports  452  of the IHS  450  over the first surface  411  of the package substrate  410 . 
     In an embodiment, the primary thermal path through the package substrate  410  may include thermal vias  415 . The thermal vias  415  may be below a footprint of the first die  442 . In some embodiments, the thermal vias  415  pass through an entire thickness of the package substrate  410 . For example, the pair of thermal vias  415  on the right side of the package substrate  410  pass through the entire thickness of the package substrate  410 . In other embodiments, thermal vias  415  may optionally be used in conjunction with other thermal features. For example, thermal vias  415  may be thermally coupled to traces  417  and/or thermal slugs  416  embedded in the package substrate  410 . 
     In an embodiment, the primary thermal path for heat transferred from the bottom die  442  to the IHS  450  outside of the package substrate  410  is provided along the WAHS  420 . The WAHS  420  may comprise a first portion  421  secured to the first surface  411  of the package substrate  410 , and a second portion  422  secured to the second surface  412  of the package substrate  410 . A third portion  423  passes over the sidewall  413  of the package substrate  410  and connects the first portion  421  to the second portion  422 . In an embodiment, the WAHS  420  is a monolithic structure that is flexible to allow for the attachment to both the first surface  411  and the second surface  412  of the package substrate  410 . The WAHS  420  is a structure with a high in-plane thermal conductivity. For example, the WAHS  420  may comprise high conductivity graphite or graphene sheets, a heat pipe, or a vapor chamber. 
     In an embodiment, the first portion  421  of the WAHS  420  is secured to the first surface  411  of the package substrate  410  by a sealant  432  or other adhesive. In an embodiment, the second portion  422  of the WAHS  420  is secured to the second surface  412  of the package substrate  410  by a TIM  431 . The use of a TIM  431  allows for improved thermal propagation from the bottom of the thermal features in the package substrate  410  (e.g., thermal vias  415 , thermal slugs  416 , etc.) to the WAHS  420 . In an embodiment, the TIM  431  is over an entire interface between the WAHS  420  and the second surface  412  of the package substrate  410 . This allows for thermal energy to be pulled from the package substrate  410  even outside of the thermal features (e.g., thermal vias  415 , thermal slugs  416 , etc.). 
     In an embodiment, the second portion  422  of the WAHS  420  extends below a footprint of the first die  442 . Accordingly, the primary thermal path through the package substrate  410  may be a substantially vertical path in some embodiments. For example, on the right side of the package substrate  410 , thermal vias  415  drop vertically from below the first die  442  and are thermally coupled to the second portion  422  of the WAHS  420  by the TIM  431 . 
     In an embodiment, the second portion  422  of the WAHS  420  is routed to avoid the interconnects  463 . As shown, the second level interconnects (SLIs)  463  are positioned between the pair of second portions  422 . In an embodiment, a thickness of the WAHSs  420  is also smaller than the standoff height of the SLIs  463 . Accordingly, standard mounting processes may be used to secure the electronic package  400  to a board or the like. 
     In an embodiment, the thermal features may also route thermal energy from locations below the first die  442  to the periphery of the package substrate  410 . For example, one or more hot spots at various locations of the first die  442  may be thermally coupled to the WAHS  420 . An example of such routing is provided on the left side of the package substrate  410 . As shown, a via  415  may be located below a hot spot of the first die  442  and route the thermal energy towards the periphery by using thermal traces  417  or the like. In the illustrated embodiment, the thermal trace  417  is connected to a thermal slug  416 . The thermal slug  416  is thermally coupled to the second portion of the WAHS  420  by the TIM  431 . 
     In an embodiment, the WAHSs  420  are thermally coupled to the supports  452  of the IHS  450 . As shown, each of the supports  452  may land on a first portion  421  of a WAHS  420 . Thermal coupling between the bottom surface of the supports  452  and the top surface of the first portion  421  of the WAHS  420  may be improved by utilizing a TIM  433  at the interface. 
     Referring now to  FIG. 4B , a cross-sectional illustration of an electronic package  400  is shown, in accordance with an additional embodiment. The electronic package  400  in  FIG. 4B  may be substantially similar to the electronic package  400  in  FIG. 4A , with the exception that one or more components  461  are embedded in the package substrate  410 . In a particular embodiment, the component  461  is a TEC. In such embodiments, the cooling surface of the TEC  461  faces the first die  442  and the heating surface of the TEC  461  faces the bottom surface of the package substrate  410 . The bottom surface of the TEC  461  may be thermally coupled to the second portion  422  of the WAHS  420 . Accordingly, active cooling may also be used in conjunction with the WAHS  420  to provide even greater thermal control of the electronic package  400 . 
     Referring now to  FIG. 4C , a cross-sectional illustration of an electronic package  400  is shown, in accordance with an additional embodiment. In an embodiment, the electronic package  400  comprises a first die module  440  and a second die module  441 . In an embodiment, the first die module  440  is attached to the first surface  411  of the package substrate  410 , and the second die module  441  is attached to the second surface  412  of the package substrate  410 . 
     In an embodiment, the first die module  440  comprises a first die  442 . The first die  442  is thermally coupled to the main body  451  of the IHS  450  by a TIM  448 . The second die module  441  comprises a second die  455 . Since the second die  455  is on the opposite side of the package substrate  410 , there is no direct connection to the IHS  450 . Accordingly, embodiments include using the WAHSs  420  to route thermal energy from the second die  455  to the supports  452  of the IHS  450 . 
     In an embodiment, the second die  455  is attached to the second surface  412  of the package substrate  410  by interconnects  457 . The interconnects  457  may be surrounded by an underfill  456 . In an embodiment, the underfill  456  is a high thermal conductivity underfill  456 . For example, the underfill  456  may comprise epoxy with high thermal conductivity fillers or the like. The underfill  456  may be in direct contact with the second portions  422  of the WAHSs  420 . Accordingly, thermal energy from the second die  455  is propagated through the underfill  456  to the WAHS  420 , and up to the support  452  of the IHS  450 . Accordingly, the thermal energy does not need to pass through the organic package substrate  410  that has a low thermal conductivity. 
     Referring now to  FIG. 4D , a plan view illustration of the second surface  412  of the electronic package  400  in  FIG. 4C  is shown, in accordance with an embodiment. As shown, the second portions  422  extend along the second surface  412  and are in contact with the underfill  456 . In some embodiments, the second portions  422  extend below the underfill  456 . The plan view illustration also depicts the clearance for the SLIs  463 . As shown, the SLIs  463  are in rows that are out of the plane illustrated in  FIG. 4C . 
     Referring now to  FIG. 5 , a cross-sectional illustration of an electronic system  590  is shown, in accordance with an embodiment. In an embodiment, the electronic system  590  comprises an electronic package  500  that is secured to a board  591 . The board  591  may be a motherboard or the like. In an embodiment, the electronic package  500  is attached to the board  591  with interconnects  563 . In the illustrated embodiment, the interconnects  563  are shown as solder balls, but it is to be appreciated that any suitable interconnect architecture may be used so long as there is clearance for the WAHS  520 . For example, a standoff height T 1  of the interconnects  563  will be larger than a combined thickness T 2  of the second portion  522  of the WAHS  520  and any adhesive (or TIM) used to secure the second portion  522  to the second surface  512 . 
     In an embodiment, the electronic package  500  comprises a package substrate  510 , a WAHS  520 , a die module  540 , and an IHS  550 . In an embodiment, the die module  540  may comprise one or more dies. For example, a 3D die architecture is shown in  FIG. 5 . While an electronic package  500  with a single die module  540  over a first surface  511  of the package substrate  510  is shown, it is to be appreciated that electronic packages  500  with any number of die modules  540  over one or both surfaces  511  and  512  may be included in the electronic package  500 . 
     In an embodiment, the WAHS  520  comprises a first portion  521  on the first surface  511  of the package substrate  510 , a second portion  522  on the second surface  512  of the package substrate  510 , and a third portion  523  that wraps along a sidewall surface  513  of the package substrate  510 . The WAHS  520  may be thermally coupled to thermal features  515  and/or  516  in the package substrate  510  and to the IHS  550  by a TIM or the like. 
       FIG. 6  illustrates a computing device  600  in accordance with one implementation of the invention. The computing device  600  houses a board  602 . The board  602  may include a number of components, including but not limited to a processor  604  and at least one communication chip  606 . The processor  604  is physically and electrically coupled to the board  602 . In some implementations the at least one communication chip  606  is also physically and electrically coupled to the board  602 . In further implementations, the communication chip  606  is part of the processor  604 . 
     These other components include, but are not limited to, volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), flash memory, a graphics processor, a digital signal processor, a crypto processor, a chipset, an antenna, a display, a touchscreen display, a touchscreen controller, a battery, an audio codec, a video codec, a power amplifier, a global positioning system (GPS) device, a compass, an accelerometer, a gyroscope, a speaker, a camera, and a mass storage device (such as hard disk drive, compact disk (CD), digital versatile disk (DVD), and so forth). 
     The communication chip  606  enables wireless communications for the transfer of data to and from the computing device  600 . 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. The communication chip  606  may 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, 5G, and beyond. The computing device  600  may include a plurality of communication chips  606 . For instance, a first communication chip  606  may be dedicated to shorter range wireless communications such as Wi-Fi and Bluetooth and a second communication chip  606  may be dedicated to longer range wireless communications such as GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others. 
     The processor  604  of the computing device  600  includes an integrated circuit die packaged within the processor  604 . In some implementations of the invention, the integrated circuit die of the processor  604  may be part of an electronic package that comprises a WAHS that wraps from a first surface to a second surface of the package substrate, in accordance with embodiments described herein. The term “processor” may refer to any device or portion of a device that processes electronic data from registers and/or memory to transform that electronic data into other electronic data that may be stored in registers and/or memory. 
     The communication chip  606  also includes an integrated circuit die packaged within the communication chip  606 . In accordance with another implementation of the invention, the integrated circuit die of the communication chip  606  may be part of an electronic package that comprises a WAHS that wraps from a first surface to a second surface of the package substrate, in accordance with embodiments described herein. 
     The above description of illustrated implementations of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific implementations of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. 
     These modifications may be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific implementations disclosed in the specification and the claims. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation. 
     Example 1: an electronic package, comprising: a package substrate with a first surface, a second surface opposite from the first surface, and a sidewall surface connecting the first surface to the second surface; and a heat spreader, wherein a first portion of the heat spreader is attached to the first surface of the package substrate and a second portion of the heat spreader is attached to the second surface of the package substrate, and wherein a third portion of the heat spreader adjacent to the sidewall surface of the package substrate connects the first portion of the heat spreader to the second portion of the heat spreader. 
     Example 2: the electronic package of Example 1, wherein the third portion of the heat spreader is spaced away from the sidewall surface of the package substrate. 
     Example 3: the electronic package of Example 1, wherein the third portion of the heat spreader is secured to the sidewall surface of the package substrate. 
     Example 4: the electronic package of Examples 1-4, further comprising: a via through the package substrate from the first surface to the second surface, wherein the via is thermally coupled to the second portion of the heat spreader. 
     Example 5: the electronic package of Examples 1-4, further comprising: a thermally conductive slug embedded in the package substrate, wherein the thermally conductive slug is thermally coupled to the second portion of the heat spreader. 
     Example 6: the electronic package of Example 5, wherein the thermally conductive slug is thermally coupled to a component embedded in the package substrate. 
     Example 7: the electronic package of Example 6, wherein the component is a thermoelectric cooler, a capacitor, or a voltage regulator. 
     Example 8: the electronic package of Examples 1-7, wherein a first length of the first portion is smaller than a second length of the second portion. 
     Example 9: the electronic package of Examples 1-8, further comprising: a plurality of heat spreaders. 
     Example 10: the electronic package of Examples 1-9, wherein the heat spreader is flexible and wraps around the sidewall surface of the package substrate. 
     Example 11: the electronic package of Examples 1-10, wherein the heat spreader comprises, high thermal conductivity graphite, graphene sheets, a heat pipe, or a vapor chamber. 
     Example 12: an electronic package, comprising: a package substrate with a first surface and a second surface; a heat spreader that is attached to the first surface and the second surface of the package substrate; a first die module attached to the first surface of the package substrate; and an integrated heat spreader (IHS) that is thermally coupled to the heat spreader and the first die module. 
     Example 13: the electronic package of Example 12, wherein the first die module comprises: a first die that is attached to the first surface of the package substrate; and a plurality of second dies stacked over the first die. 
     Example 14: the electronic package of Example 12, further comprising: a second die module attached to the second surface of the package substrate. 
     Example 15: the electronic package of Examples 12-14, wherein the IHS comprises: a main body; and one or more supports extending down from the main body, wherein the main body is thermally coupled to the first die module, and wherein one or more of the supports are thermally coupled to the heat spreader. 
     Example 16: the electronic package of Examples 12-15, further comprising: one or more thermally conductive paths through the package substrate, wherein the one or more thermally conductive paths thermally couple the first die module to the heat spreader. 
     Example 17: the electronic package of Example 16, wherein the one or more thermally conductive paths comprise vias through a thickness of the package substrate. 
     Example 18: the electronic package of Example 16, wherein the one or more thermally conductive paths comprise metal traces or thermal slugs embedded in the package substrate. 
     Example 19: the electronic package of Examples 12-18, further comprising: a thermoelectric cooler with a cooling surface and a heating surface embedded in the package substrate within a footprint of the first die module, wherein the cooling surface faces the first die module, and wherein the heating surface is thermally coupled to the heat spreader by a thermally conductive path. 
     Example 20: the electronic package of Examples 12-19, further comprising: one or more passive devices embedded in the package substrate or on a surface of the package substrate, wherein the one or more passive devices are thermally coupled to the heat spreader by a thermally conductive path. 
     Example 21: the electronic package of Examples 12-20, further comprising: second level interconnects attached to the second surface of the package substrate, wherein the second level interconnects have a first thickness, and wherein the heat spreader has a second thickness that is less than the first thickness. 
     Example 22: the electronic package of Examples 12-21, wherein a first portion of the heat spreader attached to the first surface of the package substrate is outside of a footprint of the first die module, and wherein a second portion of the heat spreader attached to the second surface of the package substrate is at least partially within the footprint of the first die module. 
     Example 23: electronic system, comprising: a die module; an electronic package electrically coupled to the die module by first interconnects, wherein the electronic package comprises a first surface and a second surface opposite from the first surface; a heat spreader attached to the first surface and the second surface of the electronic package; an integrated heat spreader (IHS) thermally coupled to the die module and the heat spreader; and a board electrically coupled to the electronic package by second interconnects. 
     Example 24: the electronic system of Example 23, wherein the heat spreader is flexible and wraps around a sidewall surface of the electronic package. 
     Example 25: the electronic system of Example 23 or Example 24, wherein the heat spreader comprises, high thermal conductivity graphite, graphene sheets, a heat pipe, or a vapor chamber.