Thermal management using the change in thermal resistance of a thermal interface

Abstract

The thermal management system includes an integrated circuit having an active side including a control circuit and a backside including a first set of electrodes dispersed across the backside. The thermal management system includes a heat exchanger having a surface including a second set of electrodes. The thermal management system includes a thermal interface material including thermally conductive particles suspended in a fluid. The thermal interface material is disposed between the backside of the integrated circuit and the surface of the heat exchanger. The control circuit is configured to apply an electric field to the thermal interface material using a first electrode of the first set of electrodes and a second electrode of the second set of electrodes to excite at least a portion of the thermally conductive particles between the first electrode and the second electrode.

Description

Background Art

[0001] Generally, thermal management technology improves reliability and reduces or eliminates early failures of integrated circuit products caused by heat generated by the integrated circuit products. Technologies used to cool integrated circuit products (e.g., heat sinks, forced air systems, fans, heat pipes, thermoelectric devices) typically cool the entire integrated circuit product. Hot spots are relatively small or local areas of an integrated circuit product that have a higher temperature compared to the temperature of the rest of the integrated circuit product. By cooling the entire integrated circuit product, conventional thermal management technologies may cause unnecessary overcooling of integrated circuit products that are prone to hot spots. Therefore, technologies for locally cooling hot spots of integrated circuit products are desired.

[0002] In at least one embodiment, a thermal management system includes an integrated circuit having an active side including a control circuit, and a back side including a first set of electrodes distributed across the back side. The thermal management system includes a heat exchanger having a surface including a second set of electrodes. The thermal management system includes a thermal interface material including thermally conductive particles suspended in a fluid. The thermal interface material is disposed between the back side of the integrated circuit and the surface of the heat exchanger. The thermal interface material is in contact with the back side of the integrated circuit and the surface of the heat exchanger. The control circuit is configured to apply an electric field to the thermal interface material using a first electrode of the first set of electrodes and a second electrode of the second set of electrodes to excite at least some of the thermally conductive particles between the first electrode and the second electrode. In at least one embodiment, the electric field is a non-uniform electric field. In at least one embodiment, the electric field causes at least some of the thermally conductive particles to form a high thermal conductivity path in the thermal interface material between the first electrode and the second electrode. The high thermal conductivity path has a lower thermal resistance than a region of the thermal interface material having randomly dispersed thermally conductive particles suspended in a fluid. In at least one embodiment, the first electrode is proximate to a hot spot location of the integrated circuit. In at least one embodiment, the electric field is generated using an alternating current provided by the integrated circuit. In at least one embodiment, the electric field is an alternating electric field having a magnitude, frequency, waveform, and phase determined by the control circuit. In at least one embodiment, the radius of the thermally conductive particles, a first permittivity, a first conductivity, a second permittivity of the fluid, and a second conductivity have values that cause a chain of the thermally conductive particles in the fluid in response to the electric field. In at least one embodiment, the first electrode and the second electrode are an asymmetric pair of electrodes. In at least one embodiment, the control circuit is configured to select the first electrode from the first set of electrodes based on the hot spot location. In at least one embodiment, the thermal management system further includes a plurality of sensors configured to sense a local temperature of the integrated circuit. The hot spot location is identified based on temperature information provided by the plurality of sensors. In at least one embodiment, the hot spot location is identified based on workload information of the integrated circuit.In at least one embodiment, the control circuit is configured to periodically update the hot spot position and enable a third electrode among a first set of electrodes according to the updated hot spot position. In at least one embodiment, the control circuit includes a memory element and a processor configured to execute instructions stored in the memory element and executable by the processor, and the instructions cause the processor to generate a signal for applying an electric field to the thermal interface material.

[0003] In at least one embodiment, a method for thermal management of an integrated circuit product includes selecting a first electrode of a first set of electrodes distributed across the backside of the integrated circuit and a second electrode of a second set of electrodes on a surface of a heat exchanger. The method includes applying an electric field across a thermal interface material using the first electrode and the second electrode. The thermal interface material includes thermally conductive particles suspended in a fluid. The thermal interface material is disposed between the backside of the integrated circuit and the surface of the heat exchanger. The thermal interface material is in contact with the backside of the integrated circuit and the surface of the heat exchanger. The electric field excites at least some of the thermally conductive particles between the first electrode and the second electrode. In at least one embodiment of the method, the electric field is a non-uniform electric field. In at least one embodiment of the method, the electric field causes at least some of the thermally conductive particles to align, thereby forming a high thermal conductivity path of the thermal interface material between the first electrode and the second electrode. The high thermal conductivity path has a lower thermal resistance than a region of the thermal interface material having randomly dispersed thermally conductive particles suspended in the fluid. In at least one embodiment, the first electrode is proximate to a hot spot location of the integrated circuit. In at least one embodiment, the electric field is generated using an alternating current. In at least one embodiment, the method further includes identifying a hot spot location of the integrated circuit, and the first electrode is selected based on the hot spot location. In at least one embodiment, the method further includes sensing a local temperature of the integrated circuit, and the hot spot location is identified based on the local temperature. In at least one embodiment, the hot spot location is identified based on workload information. In at least one embodiment, the method further includes periodically updating the hot spot location of the integrated circuit and enabling a third electrode of the first set of electrodes according to the updated hot spot location. In at least one embodiment, the thermally conductive particles suspended in the fluid are conductive particles. In at least one embodiment, the radius of the thermally conductive particles, a first permittivity, a first conductivity, a second permittivity, and a second conductivity of the fluid have values that cause a chain of the thermally conductive particles in the fluid in response to the electric field.

[0004] In at least one embodiment, a method for manufacturing a thermal management system includes providing an integrated circuit having an active side including a control circuit and a back side including a first set of electrodes dispersed across the back surface. The method includes providing a heat exchanger having a surface including a second set of electrodes. The method includes providing a thermal interface material including thermally conductive particles suspended in a fluid. The thermal interface material is disposed between the back side of the integrated circuit and the surface of the heat exchanger. The thermal interface material is in contact with the back side of the integrated circuit and the surface of the heat exchanger. The control circuit is configured to apply an electric field to the thermal interface material using a first electrode of the first set of electrodes and a second electrode of the second set of electrodes to excite at least some of the thermally conductive particles between the first electrode and the second electrode. In at least one embodiment, the method further includes forming the first set of electrodes on the back side of the integrated circuit, forming a passivation layer on the surface of the heat exchanger, and forming a second set of electrodes electrically insulated from the heat exchanger by the passivation layer. In at least one embodiment, the radius of the thermally conductive particles, the first permittivity, the first conductivity, the second permittivity of the fluid, and the second conductivity have values that cause a chain of the thermally conductive particles in the fluid in response to the electric field. In at least one embodiment, the first electrode and the second electrode are an asymmetric pair of electrodes.

[0005] The present invention can be better understood by reference to the accompanying drawings, in which many of the objects, features, and advantages will be apparent to those skilled in the art.

Brief Description of the Drawings

[0006]

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DETAILED DESCRIPTION OF THE INVENTION

[0007] When the same reference numerals are used in different drawings, they indicate similar or identical items.

[0008] Referring to FIGS. 1 and 2, an exemplary integrated circuit product (e.g., an integrated circuit die, a multi-chip module, or an integrated circuit die or multi-chip module attached to an interposer or package substrate) includes regions that operate at different power densities. For example, regions 104 and 106 operate at a higher power density than the power density of region 103. Region 104 may have a higher power density at different times than region 106. Regions 104 and 106 create associated hot spots on integrated circuit product 102. An exemplary thermal management system 100 includes a heat exchanger 110 (e.g., a heat spreader, a heat sink, a package lid, or other heat transfer structure) that contacts the surface of the integrated circuit product (e.g., the back side of the integrated circuit die in a flip-chip device, the back side of a substrate attached to the integrated circuit die) through a thermal interface material 108 between the heat exchanger 110 and the surface of the integrated circuit product. The heat exchanger 110 transfers thermal energy from the integrated circuit product 102 at a high temperature to another object at a low temperature (e.g., air).

[0009] The thermal interface material 108 fills the gap between the heat transfer surface of the integrated circuit product 102 and the heat exchanger 110 to enhance the heat transfer efficiency. In at least one embodiment, the thermal interface material 108 is a fluid (e.g., a non-curing polymer matrix, a silicone-based fluid, a poly-synthetic oil), and thermally conductive particles (e.g., silver, aluminum, aluminum oxide, zinc oxide, boron nitride) are added to improve the thermal conductivity of the compound (i.e., reduce the thermal resistance). Generally, the thermally conductive particles are randomly dispersed throughout the fluid. The thermal interface material 108 has an effective thermal conductivity (e.g., 3 - 6 W / mK) that does not substantially change over time or with operating conditions.

[0010] Thermal management techniques increase the thermal conductivity of a thermal interface material in a local region thereof by aligning the thermally conductive particles within the thermal interface material to form a high thermal conductivity path between the surface of an integrated circuit product and the surface of a heat exchanger. Referring to FIG. 3, the thermal interface material 208 is a compound that includes a fluid (e.g., a non-curing polymer matrix, a silicone-based fluid, a poly-synthetic oil) and thermally conductive particles (e.g., silver, aluminum, aluminum oxide, zinc oxide, boron nitride). The fluid has a viscosity that is low enough (e.g., less than 250 Pascal seconds) to allow the thermally conductive particles to move within the fluid of the compound. In at least one embodiment of the thermal interface material 208, the thermally conductive particles are silver particles (e.g., microparticles or nanoparticles) having a thermal conductivity of about 406 W / (mK), although in other embodiments, particles of gold, copper, or aluminum are included. In one embodiment, the thermal interface material 208 has a thickness in the range of 20 to 100 μm. A metal-based thermal interface material may be conductive and capacitive. When a metal-based thermal interface material is in contact with a circuit, the thermal interface material may cause a malfunction of the circuit or damage the circuit. In at least one embodiment of the thermal interface material 208, other thermally conductive particles that are electrical insulators (e.g., micronized diamond particles having a high thermal conductivity of about 1000 W / mK) may be used.

[0011] Referring to FIGS. 3 and 4, in at least one embodiment, the thermal management system 200 uses dielectrophoretic force to polarize neutral thermal conductive particles, i.e., the thermal conductive particles in the thermal interface material 208. The dielectrophoretic force excites the particles, causes the movement of the particles, or aligns a plurality of particles between the hot spot of the integrated circuit product 202 and the heat exchanger 210, and forms a high thermal conductivity path 216 between the electrode 214 proximate to the hot spot of the integrated circuit product 202 and the electrode 212 (e.g., heat spreader, heat sink, heat transfer structure) of the heat exchanger 210. The high thermal conductivity path 216 has a lower thermal resistance than other portions of the thermal interface material 208 having randomly dispersed thermal conductive particles. In at least one embodiment, the heat exchanger 210 has a smooth and flat contact surface for establishing thermal contact with the surface of the integrated circuit product 202 (e.g., the back side of the integrated circuit die). In other embodiments, the heat exchanger 210 includes a textured (e.g., having a serrated surface) contact surface for increasing the surface area for establishing thermal contact with another surface of the integrated circuit product 202 (e.g., the back side of the integrated circuit die). An exemplary serrated surface creates the position of the electrode within the region of increased surface area. In some embodiments, the heat exchanger 201 includes a contact surface that includes a smooth region and a textured region proximate to the expected position of the hot spot. By exciting (e.g., polarizing in situ), concentrating, or aligning the thermal conductive particles between the hot spot of the integrated circuit product 202 and the heat exchanger 210, the thermal management system 200 reduces the effective thermal resistance of the high thermal conductivity path between the hot spot of the integrated circuit product 202 and the heat exchanger 210 as compared to the region of the thermal interface material 208 having randomly dispersed thermal conductive particles.

[0012] Generally, the dielectrophoretic movement of polarized neutral heat-conductive particles occurs in response to the forces applied to the neutral heat-conductive particles when it is subjected to a non-uniform electric field. The dielectrophoretic force generates a movement that depends on the gradient of the electric field. The gradient of the electric field can be generated by using asymmetric electrodes (e.g., electrodes formed using different shapes, non-uniform shapes, or different materials) that change the phase of the electric field, or by other suitable techniques.

[0013] In at least one embodiment of the thermal management system 200, the non-uniform electric field is a non-uniform alternating current (AC) electric field or a non-uniform direct current (DC) electric field. The force applied to the heat-conductive particles by AC dielectrophoresis is controlled by adjusting the field parameters (e.g., magnitude, frequency, waveform, wave symmetry, and phase). The sign and magnitude of the dipoles induced in the heat-conductive particles are given by the real part of the Clausius-Mossotti function K,

Equation

Equation

[0014] Generally, the dielectrophoretic effect causes structuring when a high concentration of heat-conductive particles is present between the electrodes. In various embodiments, the particle size varies from nanometers to micrometers. When the heat-conductive particles are sufficiently close, the dipoles induced in the heat-conductive particles interact with each other. The heat-conductive particles align in chains along the direction of the field lines. The chain force F chain is proportional to the square of the electric field strength E 2 and the square of the radius of the particle r 2Depends on

number

[0015] The thermal management system 200 applies an AC or DC signal to at least one pair of selectively enabled electrodes to generate an AC or DC field, respectively, across the thermal interface material 208. In some embodiments, the thermal management system applies a pulse of electric charge using the selectively enabled electrodes to induce small movements of thermally conductive particles in the thermal interface material 208 to enhance heat transfer. Each pair of selectively enabled electrodes includes an electrode on a surface of the integrated circuit product 202 and an electrode on a surface of the heat exchanger 210. In an embodiment of the thermal management system 200, an electrode 214 selected from a plurality of electrodes on the backside of the integrated circuit product 202 and an electrode 212 of the heat exchanger 210 are asymmetric. For example, the electrode 214 has a different thickness or shape than the electrode 212, even if both sets of electrodes are formed from the same material (e.g., thin film conductor). In at least one embodiment, a different number of electrodes on the surfaces of the integrated circuit product 202 and the heat exchanger 210 are selected to generate an asymmetric electric field across the thermal interface material 208. The thermal management system 200 selects at least one electrode on a surface of the heat exchanger 210 in contact with the thermal interface material 208 and at least one electrode on a surface of the integrated circuit product 202 in contact with the thermal interface material 208 to generate a non-uniform electric field that excites, concentrates or aligns a portion of the thermally conductive particles in the thermal interface material 208 to form a highly thermally conductive path between the surface of the integrated circuit product 202 and the heat exchanger 210.

[0016] Referring to FIG. 5, in at least one embodiment, an array of thin film electrodes 212 and associated electrical wiring (not shown) are formed on the surface of the integrated circuit product 202 (e.g., the back side of the integrated circuit product 202). The electrodes 212 are formed using conventional integrated circuit manufacturing techniques (e.g., forming a dielectric layer, forming one or more conductive layers (e.g., a metal layer or a redistribution layer), patterning the conductive layer (e.g., applying a photoresist, selectively exposing the photoresist using a reticle containing a conductive pad pattern, and removing unwanted material)). Note that the geometry, spacing, and shape of the electrodes vary depending on the application.

[0017] Referring to FIG. 6, a detailed view of a subset 606 of the electrodes of FIG. 5 is shown, and the selection circuit 602 receives a digital code SEL that identifies one or more electrodes selected to receive power from the power supply 604 independently of the other electrodes. The unselected electrodes are coupled to ground or another supply voltage. In at least one embodiment, the selection circuit 602 is included on the surface of the integrated circuit product 202, and the digital code SEL is received from the active side of the integrated circuit product 202. In other embodiments, the selection circuit 602 is included on the active side of the integrated circuit product 200, and the selected electrodes receive power from a selectively enabled power signal received from the active side of the integrated circuit product 202. Referring to FIG. 7, in at least one embodiment, a control signal or a power signal is received from the active side of the integrated circuit product 202 using silicon through vias. The silicon through via 708 is a vertical interconnect structure that completely penetrates the die of the integrated circuit product 202. For example, the silicon through via 708 is formed using wafer backside lithography, deep silicon etching, silicon dioxide etching using a photoresist mask (e.g., reactive ion etching (RIE)), sidewall insulation deposition (e.g., low temperature plasma enhanced chemical vapor deposition (PECVD), silicon dioxide deposition and subsequent silicon dioxide RIE), and conductive material processing. In other embodiments, the active side of the integrated circuit product 200 provides the digital code SEL to a digital signal interface, and an external conductor provides the digital code SEL to a port on the back side of the integrated circuit product 200.

[0018] The heat exchanger 210 includes a second set of one or more electrodes. In at least one embodiment, the electrodes are formed on a passivation layer (e.g., silicon nitride). The first set of electrodes and the second set of one or more electrodes are described as including a plurality of electrodes, but in at least one embodiment, the second set of electrodes includes only one electrode. In at least one embodiment, the heat exchanger 210 is coupled to the ground node of a power supply and is a thermally conductive and electrically conductive plate that functions as the only electrode of the second set of electrodes of the heat exchanger 210, and the thermal management system 200 only selectively enables the electrodes of the first set of electrodes on the back side of the integrated circuit product 202.

[0019] Referring to FIG. 8, in at least one embodiment, the integrated circuit product 202 includes a processor 402, a coprocessor 404, memory circuits 406, 408, 410, 412, an interface 416, and a thermal control device 414. In at least one embodiment, the processor 402 is a microprocessor, a central processing unit, a graphics processing unit, an acceleration processing unit, a digital signal processor, or other processing circuitry. In some embodiments, the thermal control device 414 is not included separately. In other embodiments, the thermal control device 414 is implemented using software (including firmware) executed on the processor 402 or the coprocessor 404, or by a combination of software and hardware. As described herein, the software may be encoded in the memory 406, 408, 410, 412 or at least one other tangible (i.e., non-transitory) computer-readable medium. As referred to herein, the tangible computer-readable medium includes at least one disk, tape, or other magnetic, optical, or electronic storage medium.

[0020] In one embodiment of the thermal management system 200, the thermal control device 414 generates a digital code SEL and communicates the digital code SEL or an associated selectively enabled power signal to the back side of the integrated circuit product 202. In some embodiments, the digital code SEL includes a signal for the interface 416 to communicate with the heat exchanger 210 via an external signal for selectively enabling at least one of the second set of electrodes of the heat exchanger 210. In at least one embodiment, the thermal control device 414 includes temperature sensors (e.g., diodes on the integrated circuit product 202) distributed across the active side of the integrated circuit product 202. The temperature sensors provide temperature information to the thermal control device 414 to identify hot spots on the integrated circuit product 202 during operation. In at least one embodiment, the thermal control device 414 determines a temperature difference between one region of the integrated circuit product and another region of the integrated circuit product 210, compares these temperature differences with a threshold temperature difference corresponding to the hot spot, and detects the hot spot on the integrated circuit product 202.

[0021] Referring to FIGS. 3, 4, and 8, in one embodiment, the thermal control device 414 uses the workload information of the integrated circuit product 200 as a substitute for temperature information, or in addition to temperature information, to identify the hot spots of the integrated circuit product 202. For example, the thermal control device 414 can use the workload information (e.g., program flow information) of the processor 402 and the coprocessor 404. When the workload information indicates that the coprocessor 404 is operating in a high-power mode, the thermal control device 414 enables one or more electrodes proximate to the coprocessor 404 to create one or more corresponding high-thermal-conductivity paths (e.g., high-thermal-conductivity path 216 or high-thermal-conductivity path 218) between the coprocessor 404 and the hot spots of the integrated circuit product 202 generated by the coprocessor 404 and the heat exchanger 210. In one embodiment, the thermal control device 414 periodically performs hot spot detection and updates the selected electrodes or creates additional high-thermal-conductivity paths between additional hot spots and the heat exchanger 210 to change the position of the high-thermal-conductivity paths between the hot spots and the heat exchanger 210. In at least one embodiment, the thermal control device 414 receives information regarding which core of the multi-core integrated circuit is executing the workload, and the thermal control device 414 updates the selected electrodes to create a high-thermal-conductivity path between the hot spot associated with the core executing the workload and the heat exchanger 210. The thermal control device 414 updates the selected electrodes to create a high-thermal-conductivity path at another location where the workload is being executed or disables the path to randomly disperse the thermally conductive particles through the thermal interface material to uniformly cool all the cores of the integrated circuit die.

[0022] When the program flow indicates that the coprocessor 404 is operating in the low power mode, the thermal control device 414 disables the electrodes associated with the previously enabled high thermal conductivity path. In one embodiment, a first set of electrodes on the back side of the integrated circuit product 202 is adjusted according to a predetermined hot spot of the integrated circuit product 202, and as shown in FIG. 9, has a higher density in the region associated with higher power consumption and a lower density in the region associated with lower power consumption. The electrodes in FIGS. 5, 6, and 9 are shown as square conductive pads, but in other embodiments, the electrodes have different geometries (e.g., rectangular, rhombic, or irregular shapes).

[0023] Although the thermal management system has been described in embodiments where dielectrophoretic forces are used to align thermally conductive particles suspended within the thermal interface material and reduce the thermal resistance of the path within the thermal interface material between the hot spot of the integrated circuit product 202 and the heat exchanger 210, those skilled in the art will be able to utilize the teachings herein with electrophoresis, magnetophoretic movement of thermally conductive particles, or electro-magnetophoretic movement of thermally conductive particles and understand that a high thermal conductivity path of the thermal interface material between the hot spot of the integrated circuit product 202 and the heat exchanger 210 can be generated. For example, in one embodiment, the thermal interface material 208 includes magnetic thermally conductive particles (e.g., iron oxide particles coated with gold), and a magnetic field gradient causes the magnetophoretic movement of the thermally conductive particles to form a path having a higher thermal conductivity compared to the thermal conductivity of the fluid in which the thermally conductive particles are randomly dispersed. Embodiments using electro-magnetophoresis generate a magnetic field using electrodes or actual magnets, and this magnetic field applies a force to the particles to excite, translate, or align the particles, and uses the movement of the thermally conductive particles due to the Lorentz force generated by simultaneously applying an electric current and a magnetic field to the thermally conductive particles to form a path having a higher thermal conductivity compared to the thermal conductivity of the fluid having randomly dispersed thermally conductive particles.

[0024] Accordingly, heat management techniques have been described that cool hot spots without supercooling other parts of the integrated circuit product. The description of the invention set forth herein is illustrative and is not intended to limit the scope of the invention as set forth in the following claims. Modifications and variations of the disclosed embodiments may be made based on the description presented herein without departing from the scope of the invention as shown in the following claims.

Claims

1. A thermal management system, comprising: an integrated circuit having an active side including a control circuit and a back side including a first set of electrodes distributed across the back side; a heat exchanger having a surface including a second set of electrodes; a thermal interface material including thermally conductive particles suspended in a fluid, the thermal interface material being disposed between the back side of the integrated circuit and the surface of the heat exchanger and in contact with the back side of the integrated circuit and the surface of the heat exchanger; the control circuit being configured to apply an electric field to the thermal interface material using a first electrode of the first set of electrodes and a second electrode of the second set of electrodes to excite at least a portion of the thermally conductive particles between the first electrode and the second electrode; A thermal management system.

2. The electric field is a non-uniform electric field. The thermal management system of Claim 1.

3. The electric field forms a high thermal conductivity path in the thermal interface material between the first electrode and the second electrode in at least a portion of the thermally conductive particles, the high thermal conductivity path having a lower thermal resistance than a region of the thermal interface material having randomly dispersed thermally conductive particles suspended in the fluid. The thermal management system of Claim 1.

4. The first electrode is proximate to a hot spot location of the integrated circuit. The thermal management system of Claim 1.

5. The electric field is generated using an alternating current supplied by the integrated circuit. The thermal management system of Claim 1.

6. The electric field is an alternating electric field having a magnitude, frequency, waveform, and phase determined by the control circuit. The thermal management system of Claim 1.

7. The radius, first permittivity, and first conductivity of the thermally conductive particles and the second permittivity and second conductivity of the fluid have values that cause a chain of the thermally conductive particles in the fluid in response to the electric field. The thermal management system of Claim 1.

8. The first electrode and the second electrode are an asymmetric pair of electrodes. The thermal management system of Claim 1.

9. The control circuit is configured to select the first electrode from the first set of electrodes based on a hot spot location, The thermal management system further comprises: a plurality of sensors configured to sense a local temperature of the integrated circuit. The hot spot position is identified based on temperature information provided by the plurality of sensors, The control circuit is configured to periodically update the hot spot position and enable a third electrode among the first set of electrodes according to the updated hot spot position, The thermal management system according to any one of claims 1 to 8.

10. The control circuit is configured to select the first electrode from the first set of electrodes based on the hot spot position, The hot spot position is identified based on the workload information of the integrated circuit, The control circuit is configured to periodically update the hot spot position and enable a third electrode among the first set of electrodes according to the updated hot spot position, The thermal management system according to any one of claims 1 to 8.

11. A method for thermal management of an integrated circuit product, comprising: selecting a first electrode from a first set of electrodes distributed across the back side of the integrated circuit and a second electrode from a second set of electrodes on the surface of the heat exchanger; applying an electric field to a thermal interface material using the first electrode and the second electrode, the thermal interface material including thermally conductive particles suspended in a fluid, the thermal interface material being disposed between the back side of the integrated circuit and the surface of the heat exchanger, the thermal interface material being in contact with the back side of the integrated circuit and the surface of the heat exchanger, the electric field exciting at least some of the thermally conductive particles between the first electrode and the second electrode; Method.

12. The electric field is a non-uniform electric field, The electric field aligns at least some of the thermally conductive particles, thereby forming a high thermal conductivity path of the thermal interface material between the first electrode and the second electrode, the high thermal conductivity path having a lower thermal resistance than a region of the thermal interface material having randomly dispersed thermally conductive particles suspended in the fluid; The method according to claim 11.

13. identifying a hot spot position of the integrated circuit; sensing a local temperature of the integrated circuit; further comprising periodically updating the hot spot position of the integrated circuit and enabling a third electrode among the first set of electrodes according to the updated hot spot position; The first electrode is selected based on the hot spot position, The hot spot position is specified based on the local temperature. The method according to claim 11 or 12.

14. Specifying the hot spot position of the integrated circuit; Further comprising periodically updating the hot spot position of the integrated circuit and enabling a third electrode among the first set of electrodes according to the updated hot spot position; The first electrode is selected based on the hot spot position; The hot spot position is specified based on workload information; The method according to claim 11 or 12.

15. The radius, first permittivity, and first conductivity of the thermally conductive particles, and the second permittivity and second conductivity of the fluid have values that cause a chain of the thermally conductive particles in the fluid in response to the electric field. The method according to claim 11 or 12.

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