Apparatus and method for thermal management of high-power electronic components using graphite bars
The use of thermally conductive graphite bars with a flexible adhesive and heat sink addresses inefficiencies in thermal management of high-power flip-chip components, enhancing thermal performance and durability in space applications.
Patent Information
- Application Number
- JP2024203209
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-12-22
- Filing Date
- 2024-11-21
- Publication Date
- 2025-07-03
AI Technical Summary
Existing thermal management systems for high-power flip-chip electronic components in space applications, such as satellites, are inefficient, complex, heavy, and prone to thermal fatigue, with conventional solutions like heat pipes and thermal straps having drawbacks that lead to component degradation.
A cooling device using thermally conductive graphite bars attached to a frame, with a flexible adhesive and heat sink, that facilitates heat extraction along specific axes to manage thermal output effectively.
The system provides high thermal conductivity with low mass, reducing thermal fatigue and assembly complexity, extending the operating life of electronic components while maintaining structural integrity.
Smart Images
Figure 2025100380000001_ABST
Abstract
Description
Technical Field
[0001] The following generally relates to thermal management in space applications, and more particularly to thermal management of high-power flip-chip electronic components.
Background Art
[0002] Cooling of computer components, such as high-power microprocessors, is an important consideration in the operability and durability of computer components. The power dissipation of flip-chip electronic components such as field programmable gate arrays (FPGAs), ball grid arrays (BGAs), column grid arrays (CCGAs), etc. has increased dramatically over the past decade along with more stringent design requirements such as data retention. The importance of thermal management and thermal fatigue limitation of electronic components is particularly challenging in space-based applications. An important goal enabling electronic components in spaceflight, particularly on, in, or for spacecraft, is to provide effective thermal control to reduce or avoid thermal fatigue and thermal runaway.
[0003] A flip-chip electronic component refers to an electronic component in which a die (for dissipating heat) is sandwiched between a substrate and a lid. Thus, the main thermal path of a flip-chip electronic component is from the die to the lid, which is approximately 10 times more efficient than the path from the die through the substrate to the column.
[0004] One approach to thermal management of electronic components in space applications is to use heat pipes. However, heat pipes are complex to assemble, mount, maintain, and operate efficiently at low temperatures. These drawbacks result in inefficiencies when used with computer components such as high-power microprocessors. Also, when computer components are deployed in an environment where servicing or reassembly is not easily possible, such as when mounted on a satellite in orbit, these drawbacks can lead to complete degradation of the computer components. The drawbacks include, for example, high cost, extensive screening, anti-gravity effects, greater design complexity, and more complex assembly procedures.
[0005] Another approach to thermal management of electronic components in space applications is to use thermal straps. Conventional thermal straps have insufficient thermal performance and / or are heavy in mass. Copper straps provide twice the thermal performance compared to aluminum straps, but copper straps have the disadvantage of being approximately three times heavier than aluminum straps and graphite straps, so they are heavy in mass.
[0006] A specific approach to thermal straps is the use of graphite straps, which provide approximately three times the thermal conductivity of copper straps and save more than 70% in mass. However, graphite strips are composed of thin graphite layers that may not be oriented in the direction of heat flow. Summary of the Invention Problems to be Solved by the Invention
[0007] Accordingly, there is a need for an improved system, apparatus, and method for managing the thermal output of flip-chip electronic components in space-based applications, such as satellite-mounted processors using digital processing components, that overcome the drawbacks of existing systems and methods. Means for Solving the Problems
[0008] A cooling device for cooling an electronic component is provided. The cooling device includes at least one graphite bar attached to a frame. The at least one graphite bar is thermally conductive along a first axis and a second axis. The second axis is perpendicular to the first axis and parallel to the length of the at least one graphite bar. The frame is for attaching the at least one graphite bar and includes a receiving and holding member attached and thermally coupled to the frame at a fixed position relative to the frame to hold the at least one graphite bar. The receiving and holding member includes a recess for receiving the at least one graphite bar, and a thermal adhesive for adhering and thermally coupling the at least one graphite bar to the receiving and holding member is disposed in the recess. A heat sink is thermally coupled to the frame. Heat is extracted from the at least one graphite bar or flows downward from the at least one graphite bar along the second axis through the receiving and holding member, to the frame, and to the heat sink.
[0009] The cooling device can further include a digital printed circuit board (''PCB'') attached to a PCB mounting platform to which the frame is attached and thermally coupled.
[0010] The cooling device can further include a flip-chip electronic component attached to the PCB at the bottom surface of the at least one graphite bar. The flip-chip electronic component includes an integrated circuit package, a top surface for dissipating heat to the at least one graphite bar, and a plurality of solder joints deposited on the chip pads of the flip-chip electronic component to interconnect the flip-chip electronic component to an external circuit on the PCB. A flexible adhesive is disposed between a portion of the bottom surface of the at least one graphite bar that overlaps the top surface of the flip-chip electronic component.
[0011] Approximately one-third of the bottom surface of the at least one graphite bar can overlap the top surface of the flip-chip electronic component.
[0012] The flexible adhesive can be applied together with a primer to strengthen the joint.
[0013] The plurality of solder joints can be solder columns.
[0014] The solder column can be coated with copper.
[0015] The plurality of solder joints can be solder balls.
[0016] At least one graphite bar may not be conductive along a third axis perpendicular to the first axis and further perpendicular to the second axis.
[0017] At least one graphite bar may be further conductive along a third axis perpendicular to the first axis and further perpendicular to the second axis.
[0018] At least one graphite bar can be composed of polycrystalline graphite.
[0019] The polycrystalline graphite can be quantumly oriented so that conduction is possible only along the first axis and along the second axis.
[0020] The polycrystalline graphite can be annealed.
[0021] At least one graphite bar can be substantially rigid.
[0022] At least one graphite bar can be flexible.
[0023] Upon consideration of the following description of some exemplary embodiments, other aspects and features will become apparent to those skilled in the art.
[0024] The drawings included herein are for the purpose of illustrating various examples of the articles, methods, and apparatuses of this specification.
Brief Description of the Drawings
[0025]
Figure 1A
Figure 1B
Figure 2A
Figure 2B
Figure 3
[0026] Various devices or processes are described below to provide an example of each of the claimed embodiments. None of the embodiments described below limit the claimed embodiments, and any of the claimed embodiments can cover processes or devices different from those described below. The claimed embodiments are not limited to a device or process having all of the features of any one of the devices or processes described below, nor to features common to a plurality or all of the devices described below.
[0027] Furthermore, process steps, method steps, algorithms, etc. may be described in sequential order (in the description and / or in the claims), but such processes, methods, and algorithms can be configured to function in an alternative order. In other words, no order or sequence of steps that can be described necessarily indicates that the steps should be performed in that order. The steps of the processes described herein can be performed in any practical order. Additionally, some steps can be performed simultaneously.
[0028] When describing a single device or article in this specification, it will be readily apparent that more than one device / article (regardless of whether they cooperate) can be used instead of a single device / article. Similarly, when describing more than one device or article in this specification (regardless of whether they cooperate), it will be readily apparent that a single device / article can be used instead of more than one device or article.
[0029] The following generally relates to thermal management in space applications, particularly to the thermal management of high-power flip-chip electronic components.
[0030] The present disclosure provides systems, devices, and methods for efficiently cooling high-power electronic components in space applications using highly conductive graphite bars. The present disclosure is particularly suitable for the thermal management of flip-chip electronic components such as those found in satellites or other space vehicles using digital PCBs. The graphite bars provide a thermal management solution that can offer various advantages such as ease of manufacture and assembly and high thermal conductivity with relatively low mass. The graphite bars provide a thermal conductivity-to-mass ratio more than twice that of other graphite thermal management solutions (e.g., graphite thermal straps). The thermal management solution provided by the present disclosure, in one embodiment, can handle more than twice that of some conventional solutions and the same power dissipation (e.g., in the context of a flip-chip) as a copper water heat pipe.
[0031] The present disclosure can have further applications in efficiently cooling digital PCBs and other mounted digital processors.
[0032] The present disclosure advantageously achieves a balance between the thermal performance, mass, and thermal fatigue / lifetime of flip-chip electronic components such as FPGAs. The present disclosure advantageously achieves lower cost as well as simpler design and assembly.
[0033] Next, referring to FIG. 1A, a system 100 for managing the thermal output of high-power electronic components of a digital PCB on a spacecraft platform according to one embodiment is shown herein.
[0034] For clarity, FIG. 1A includes the x, y, and z axes shown as such.
[0035] System 100 can be used, for example, in space-based applications (e.g., mounted on a satellite or other spacecraft) to thermally manage a digital PCB in an on-board digital processor. Such processing components are prone to thermal fatigue conditions during a mission, which can negatively affect performance, durability, and thermal runaway.
[0036] System 100 includes a digital processing unit that includes a digital PCB 102 attached to a printed circuit board (「PCB」) mounting platform 104. The PCB mounting platform 104 is a housing in which the PCB 102 is installed. The PCB mounting platform or housing 104 may be attached to a platform or panel of a satellite or other spacecraft, or it may be a separate component attached thereto.
[0037] System 100 further includes a frame 108 that includes a plurality of connected horizontal and vertical frame components. The frame 108 can form a grid-type structure. The frame 108 is attached to the digital PCB 102. In some cases, the frame can be (thermally and / or mechanically) coupled to the PCB housing 104. The frame 108 provides structural support and a thermally conductive heat path for components attached to the PCB.
[0038] System 100 further includes a flip-chip package (also referred to as a flip-chip electronic component) attached to the digital PCB 102. The flip-chip package includes a processing chip 110 (or integrated circuit package 110) and a plurality of solder joints 112. The flip-chip package can be considered a high-power electronic component. Such components dissipate heat through the top surface of the package (such a direction is referred to as the +x direction in this disclosure, and such an axis is considered the x-axis in this disclosure).
[0039] The solder joints 112 are deposited on the chip pads of the processing chip 110 to interconnect the chip 110 to an external circuit on the digital PCB 102.
[0040] The flip-chip package sinks heat from the chip 110 through the solder joints 112. Since approximately 10% of the heat passes through the solder joints, this is not an efficient heat path.
[0041] In one embodiment, the flip-chip package can be a flip-chip FPGA. In another embodiment, the flip-chip package can be a column grid array (CGA or CCGA). In another embodiment, the flip-chip package can be a ball grid array (BGA).
[0042] The solder joints 112 can be, for example, solder columns, solder balls, or any other suitable solder joints. In one embodiment, the solder joints 112 are copper-clad solder columns. Solder columns can provide more flexibility than solder balls and can reduce the stress caused by CTE mismatch. Solder columns can absorb stress and increase the reliability of the solder joints under severe operating conditions.
[0043] The copper-clad solder columns as an embodiment of the joints 112 can advantageously extend the effective operating life of the solder joints 112.
[0044] System 100 further includes a thermal management device 114 for managing the heat generated by the flip chip package. Generally, by managing the heat output, the thermal management device 114 reduces the likelihood of thermal fatigue conditions (especially at the solder joints 112) in the flip chip package. Thus, the thermal management device 114 extends the operating life of the flip chip package.
[0045] The thermal management device 114 includes a plurality of graphite bars 116. In one embodiment, the number of graphite bars 116 is two. In other embodiments, a different number of graphite bars 116 can be used. The number of graphite bars 116 used can be determined based on the size of the flip chip package and / or the power dissipation of the flip chip package. Since the width of each graphite bar 116 can be a limiting factor, the number of bars 116 can be determined based on the power dissipation and size of the FPGA.
[0046] In the particular embodiment shown in FIG. 1A, there are two graphite bars 116 arranged side by side. Note that since FIG. 1A is a side view, the second graphite bar is hidden but is understood to be present. The graphite bars 116 can be arranged such that there is a (small) gap (not shown) between the edges along the length of each graphite bar 116.
[0047] The graphite bars 116 are generally rectangular in shape. The graphite bars 116 can each have the same dimensions.
[0048] Each graphite bar 116 has a length defined by a first end 118 and a second end 120. The graphite bars 116 are attached to the top surface of the processing chip 110 of the flip chip package using the bottom surface 122 of the graphite bars 116.
[0049] In one embodiment, approximately one-third of the bottom surface 122 facing the first end 118 of the graphite bar 116 is attached to the processing chip 110. In other embodiments, the proportion of the graphite bar 116 covering or attached to the processing chip 110 may vary according to the package size.
[0050] Generally, the graphite bar 116 can be attached to the processing chip 110 such that the graphite bar 116 covers only as much surface area of the top surface of the processing chip 110. For example, the graphite bar 116 can be attached such that the entire surface area or substantially the entire surface of the processing chip 110 is covered. This enables a larger heat path from the flip chip package 110.
[0051] Thus, in some embodiments, the number and size of the graphite bars 116 may be based on the surface area of the top surface of the processing chip 110 and the dissipated power.
[0052] Those skilled in the art will understand that different thicknesses of the graphite bar 116 can be used depending on the specific application in which the bar 116 is deployed (e.g., in a high-power flip chip FPGA, in a PCB). Since the stress that can be applied to a short bar 116 is reduced by the reduction of thermal strain, the shorter the bar 116, the better its fatigue durability can be.
[0053] In some embodiments, the bar 116 can be substantially or completely rigid. In some embodiments, the bar 116 can be flexible. Some flexibility may be preferred over rigidity in order to avoid inducing parasitic loads in the solder. Although the graphite bar is inherently rigid, a flexible adhesive minimizes the rigid effect of the graphite bar.
[0054] The graphite strap is typically made of a conductive flexible sheet in the y-z plane as shown in FIGS. 1A and 1B.
[0055] In one embodiment, bar 116 is made of a conductive rigid sheet in the x-y plane. Since the conductivity in the x-y plane enables heat to be extracted along the x-axis, bar 116 functions thermally more favorably. Advantageously, the conductivity in the x-y plane further enables heat to flow out along the y-axis.
[0056] In one embodiment, bar 116 is made of polycrystalline graphite. Polycrystalline graphite is inherently conductive in two axes out of the x, y, and z axes. In one embodiment, the polycrystalline graphite is oriented such that bar 116 is conductive in the x-y plane rather than in the x-z or y-z plane.
[0057] In one embodiment, bar 116 is conductive simultaneously along each of the x, y, and z axes, i.e., simultaneously in each of the x-y, x-z, and y-z planes. The graphite bar 116 can be made isotropic with respect to conductivity in each of the x, y, and z axes. X-y-z conductivity can be used, but the thermal conductivity may decrease (e.g., from 1700 W / m·K to 1200 W / m·K).
[0058] In one embodiment, to prepare bar 116 that is conductive as described above, the polycrystalline graphite is quantumly oriented such that only the selected thermal conductivity (e.g., x-y conductivity) is possible as described above.
[0059] In one embodiment, to prepare bar 116 that is conductive as described above, the polycrystalline graphite is annealed.
[0060] In one embodiment, bar 116 is relatively short to reduce the stress applied thereto and improve its durability with respect to fatigue.
[0061] Polycrystalline graphite oriented in a specific plane (e.g., the x-y plane) can very well advantageously conduct heat. In one embodiment, bar 116 is made using any commercially available polycrystalline graphite. In one embodiment, bar 116 is made using only polycrystalline graphite suitable for quantum orientation as described above.
[0062] Advantageously, graphite bar 116 represents a much simpler and less expensive heat management technique compared to heat pipes and other conventional solutions.
[0063] Thermal management device 114 further includes a flexible adhesive 124 disposed between a portion of the bottom surface 122 of graphite bar 116 that overlaps or covers processing chip 110 and the top surface of processing chip 110.
[0064] Adhesive 124 has a bonding area and a bonding thickness. Graphite has a significant CTE mismatch with other materials (e.g., with other components of system 100). In some cases, the bonding thickness of adhesive 124 is determined and implemented such that the CTE mismatch between graphite bar 116 and PCB 102 is reduced to a level considered acceptable for the mission.
[0065] In some cases, adhesive 124 can be applied with a primer to strengthen the bond.
[0066] Generally, adhesive 124 has a thickness sufficient to allow for reduction of the CTE mismatch and to balance thermal performance and thermal fatigue. In some embodiments, adhesive 124 can be more rigid (less flexible).
[0067] In one embodiment, adhesive 124 is a highly flexible adhesive. Adhesive 124 can have a low Young's modulus value and a high fracture strain (e.g., greater than 100%).
[0068] In one embodiment, the adhesive 124 is a thermally conductive adhesive that minimizes the thermal resistance between the FPGA and the graphite bar 116 with a minimum thermal conductivity of 0.5 W / m·K.
[0069] In one embodiment, the adhesive 124 has low outgassing characteristics. The adhesive 124 can be an adhesive that meets the NASA outgassing requirements for space applications. The low outgassing characteristics can include two criteria, namely, a maximum mass loss ratio (TML) of 1.0 percent and a maximum condensable volatile condensable material ratio (CVCM) of 0.10 percent.
[0070] In one embodiment, the adhesive 124 is an adhesive that adheres well to graphite, for example, having a lap shear strength exceeding 200 psi when undercoated.
[0071] The adhesive 124 can be an adhesive with a wide durability temperature range (e.g., covering conditions from launch of a spacecraft from Earth to conditions in space). For example, the adhesive 124 can be selected or designed to have a temperature range from -55°C to +125°C and an optimal range from -40°C to +100°C.
[0072] The adhesive 124 accommodates the CTE mismatch between the graphite bar 116 and the PCB 102 (i.e., between the graphite bar 116 and the processing chip 110, between the graphite bar 116 and the receiving and holding member 126, and between the graphite bar 116 and the frame 108). The adhesive 124 reduces the problem of thermal fatigue of the flip chip package.
[0073] Generally, the adhesive 124 is a flexible adhesive or paste that is thick enough to reduce stress at the interface but thin enough to facilitate heat transfer, with a sufficient bond line thickness.
[0074] The adhesive 124 is advantageously flexible to avoid problems seen in conventional adhesives, such as solder joint cracks and cracks in the adhesive between the bar 116 and the flip chip package (e.g., due to temperature changes and CTE mismatches). The adhesive 124 can combine many advantages, including a wide temperature range, meeting NASA outgassing requirements, strong adhesion, flexibility, and thermal conductivity.
[0075] The thermal management device 114 further includes a receiving and holding member 126. In some embodiments, the receiving and holding member 126 may not be present.
[0076] The receiving and holding member 126 is attached and thermally coupled to the frame 108. The receiving and holding member 126 includes a recess (not visible) for receiving (and fixing) the second end 120 of the graphite bar 116. Generally, the receiving and holding member 126 (and its recess) is long enough to accommodate the graphite bar 116. The bar 116 and / or its second end 120 can be specially adapted to be received and held by the receiving and holding member 126.
[0077] The receiving and holding member 126 holds the graphite bar 116 in a fixed position relative to the frame. The receiving and holding member 126 is attached to the frame 108. The end frame can function as a stiffener to provide rigidity to the device 100.
[0078] The receiving and holding member 126 further includes a thermal adhesive (which may be the same as the adhesive 124) disposed in the recess of the receiving and holding member 126. The bar 116 is adhesively bonded to the receiving and holding member 126 in the recess via the thermal adhesive. The thermal adhesive fixes the graphite bar 116 to the receiving and holding member 126 and thermally couples the graphite bar 116 to the receiving and holding member 126, facilitating heat flow from the graphite bar 116 to the receiving and holding member 126 (or, in embodiments without the receiving and holding member 126, to the component to which the second end 120 of the graphite bar 116 is mechanically and thermally coupled).
[0079] The receiving and holding member 126 can advantageously receive the bar 116 with sufficient space around the bar 116 for the thermal adhesive. In one embodiment, an exact amount of the thermal adhesive is applied to create a controlled gap.
[0080] The receiving and holding member 126 encompasses the second end 120 on all planes (x, y, and z) through the thermal adhesive 124. The thermal coupling from the bar end 120 to the receiving and holding member 126 is most efficient at a larger contact area (y - z plane).
[0081] The receiving and holding member 126 is thermally coupled to a heat sink. In other embodiments, the receiving and holding member 126 can be thermally coupled to other components, such as a chassis or other frame, that create a thermal path for heat to move from the receiving and holding member 126 to the heat sink. In such embodiments, the graphite bar 116 can be attached using the thermal adhesive such that the second end 120 is at or near another component or the heat sink. Such an approach can be advantageous in some cases by reducing mass and assembly labor.
[0082] The thermal interface includes the FPGA to the graphite bar 116 through the adhesive 124, the graphite bar 116 to the receiving and holding member 126 through the adhesive 124, the receiving and holding member 126 to the frame 108, and the frame 108 to the heat sink.
[0083] The PCB housing 104 acts as a heat sink for the system 100. The heat sink receives heat processed by the system 100 and in particular by the device 114. The heat sink can include a spacecraft panel.
[0084] In one embodiment, the heat flow in the system 100 reaches from the processing chip 110 to the graphite bar 116, then to the receiving and holding member 126, then to the housing 104, and then to the spacecraft panel. The heat can then be radiated or otherwise expelled by the spacecraft panel.
[0085] An example of the visualization of the heat flow in the system 100 is shown in FIG. 1B. Arrows indicate the direction of the heat flow away from the flip chip package (through the top surface of the processing chip 110), through the graphite bar 116, to the receiving and holding member 126, and through the receiving and holding member 126 to the PCB housing 104.
[0086] Advantageously, the bar 116 can exhibit twice the performance (conductivity) compared to other graphite solutions such as graphite straps (e.g., 800 or 1500 W / m·K depending on orientation). For example, the thermal conductivity of copper is 385 W / m·K. The bar 116 can exhibit a thermal conductivity up to 1700 W / m·K.
[0087] In one embodiment, compared to the density of graphite of 2.3 g / cm 3 the density of copper is 8.9 g / cm 3 so it requires 70% less weight for 4 times the conductivity.
[0088] Advantageously, heat dissipates from the top of the cooling device 100 via bar 116, i.e., as shown in Figure 1B, heat dissipates along the x-axis. The heat further dissipates from bar 116 to the receiving and holding member 126 and through the PCB mounting platform 104 along the x-axis, along the path shown in Figure 1B.
[0089] Referring now to Figure 2A, a top view of the system 100 of Figures 1A and 1B is shown here.
[0090] Referring now to Figure 2B, an isometric view of the system 100 of Figures 1A and 1B is shown here.
[0091] In Figures 2A and 2B, both bars 116 are present and are individually labeled as 116-1 and 116-2.
[0092] Referring now to Figure 3, a flowchart of a method 300 for constructing a cooling device according to one embodiment is shown here. The cooling device of Figure 3 may be the cooling device 100 of Figures 1A, 1B, 2A, and 2B.
[0093] At 302, method 300 includes joining the bar to the receiving and holding member by filling the receiving and holding member with a thermal adhesive. In one embodiment, at 302, bar 116 is joined to receiving and holding member 126 with a thermal adhesive.
[0094] At 304, method 300 further includes placing the bar in a fixture (which aids in creating the cooling device) and applying a fastener until the bar is straight and perpendicular to the receiving and holding member. In one embodiment, at 304, bar 116 is placed in the fixture and fastener applied thereto until bar 116 is straight and perpendicular to receiving and holding member 126.
[0095] At 306, method 300 further includes dry fitting the bar and adjusting the bar until it approaches alignment with the frame and the FPGA. In one embodiment, at 306, bar 116 is dry fit and adjusted until it approaches alignment with the frame and the flip chip component (e.g., until bar 116 is substantially perpendicular to the horizontal portion of frame 108 and one of the flip chip components).
[0096] At 308, method 300 further includes placing the bar on the tooling and encapsulating all exposed edges and surfaces of the bar except for the areas in contact with the flip chip component and the receiving and holding member 126 with an encapsulation coating. In one embodiment, at 308, bar 116 is placed on the tooling and all exposed edges and surfaces of bar 116 are encapsulated with the coating.
[0097] To reduce stress on system 100, processing chip 110, and / or any additional devices or systems in which system 100 and / or processing chip 110 are embedded or otherwise implemented, the thickness of the adhesive used at ends 118 and 120 can be designed and / or implemented to allow for a certain level of tolerance, clearance, tolerance, and / or mismatch.
[0098] From the above description, examples of one or more devices, methods, or systems are provided, but it will be understood that other devices, methods, or systems may also fall within the scope of the claims as interpreted by those skilled in the art.
Description of Reference Numerals
[0099] 100 System 102 PCB 104 Housing 108 Frame 110 Processing Chip 112 Solder Joint 114 Thermal Management Device 116 Graphite Bar 118 First end 120 Second end 122 Bottom surface 124 Adhesive 126 Receiving and holding member
Claims
1. A cooling device for cooling an electronic component, at least one graphite bar attached to a frame, the at least one graphite bar being thermally conductive along a first axis and a second axis, the second axis being perpendicular to the first axis and the second axis being parallel to the length of the at least one graphite bar, the at least one graphite bar; the frame for attaching the at least one graphite bar, the frame including a receiving and holding member attached and thermally coupled to the frame to hold the at least one graphite bar in a fixed position relative to the frame, the receiving and holding member including a recess for receiving the at least one graphite bar, the frame; a thermal adhesive disposed in the recess for adhesively and thermally coupling the at least one graphite bar to the receiving and holding member; a heat sink thermally coupled to the frame comprising, heat is extracted from the at least one graphite bar or flows downward from the at least one graphite bar along the second axis through the receiving and holding member, the frame, and the heat sink; a cooling device.
2. The cooling device according to claim 1, further comprising a digital PCB attached to a printed circuit board ("PCB") attachment platform to which the frame is attached and thermally coupled.
3. A flip-chip electronic component attached to the PCB at the bottom surface of the at least one graphite bar, the flip-chip electronic component including an integrated circuit package, a top surface for dissipating heat to the at least one graphite bar, and a plurality of solder joints deposited on the chip pads of the flip-chip electronic component for interconnecting the flip-chip electronic component to an external circuit on the PCB, the flip-chip electronic component; a flexible adhesive disposed between a part of the bottom surface of the at least one graphite bar overlapping the top surface of the flip-chip electronic component further comprising the cooling device according to claim 2.
4. The cooling device according to claim 3, wherein approximately one-third of the bottom surface of the at least one graphite bar overlaps the top surface of the flip-chip electronic component.
5. The cooling device according to claim 3, wherein the flexible adhesive is applied together with a primer to strengthen the joint.
6. The cooling device according to claim 3, wherein the plurality of solder joints are solder columns.
7. The cooling device according to claim 6, wherein the solder column is wrapped with copper.
8. The cooling device according to claim 3, wherein the plurality of solder joints are solder balls.
9. The cooling device according to claim 1, wherein the at least one graphite bar is not conductive along a third axis perpendicular to the first axis and further perpendicular to the second axis.
10. The cooling device according to claim 1, wherein the at least one graphite bar is further conductive along a third axis perpendicular to the first axis and further perpendicular to the second axis.
11. The cooling device according to claim 1, wherein the at least one graphite bar is composed of polycrystalline graphite.
12. The cooling device according to claim 11, wherein the polycrystalline graphite is quantum-oriented so as to be conductive only along the first axis and along the second axis.
13. The cooling device according to claim 11, wherein the polycrystalline graphite is annealed.
14. The cooling device according to claim 1, wherein the at least one graphite bar is substantially rigid.
15. The cooling device according to claim 1, wherein the at least one graphite bar is flexible.