FLEXURAL PLATE WAVE DEVICE FOR CHIP COOLING
Methods, systems, and apparatuses are described for cooling electronic devices. The electrical device includes an integrated circuit die (IC) having opposing first and second surfaces, a plurality of interconnects on the second surface of the IC die that enable the IC die to be coupled to a substrate, and a flexural plate wave device. The flexural plate wave device is configured to generate a stream of air to flow across the electrical device to cool the IC die during operation of the IC die.
This application is a continuation of U.S. application Ser. No. 13/173,456, now allowed, filed Jun. 30, 2011, which claims the benefit of U.S. Provisional Application No. 61/376,757, filed on Aug. 25, 2010, which are both incorporated by reference herein in their entireties.
BACKGROUND OF THE INVENTION1. Field of the Invention
The invention relates generally to cooling techniques, and more particularly to techniques for cooling dies in integrated circuit packages.
2. Background
Integrated circuit (IC) dies are typically mounted in or on a package that is attached to a printed circuit board (PCB). Many types of IC packages exist, including leadless chip carriers (LCC), ball grid array (BGA) packages, quad flat packages (QFP), etc. One example advanced type of package is a wafer-level package. Different types of wafer-level packages exist, including wafer level chip scale packages (WLCSP), wafer level ball grid array (WLBGA) packages, and further types. Wafer level packages typically have an array of interconnects located on a bottom external surface of the package die, which may have the form of pads, posts, or balls/bumps (in the case of WLBGA packages). In a WLBGA package, an array of solder bump interconnects may be mounted directly to the die when the die has not yet been singulated from its fabrication wafer. As such, WLBGA packages do not include a package substrate. WLBGA packages can therefore be made very small, with high pin out, relative to other IC package types including traditional BGA packages.
IC packages often are subjected to high temperatures resulting from heat dissipation by circuitry during normal operation. These high temperatures can impair the performance of the circuits and/or cause thermal stresses in the package. Accordingly, a package sometimes includes one or more passive cooling devices, such as heat sinks, coupled to the IC die to facilitate conduction of heat away from the die. However, the mere introduction of passive cooling devices may not adequately dissipate heat from the IC die. Other techniques that are prevalent in industry use active system cooling devices, such as fans. However, in handheld devices and limited-space applications, it typically is not possible to incorporate system level cooling fans. A failure to adequately dissipate heat from the IC die may negatively affect the performance and/or reliability of the IC die.
BRIEF SUMMARY OF THE INVENTIONA system and/or method for actively cooling an electronic device using a flexural plate wave device, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims.
The accompanying drawings, which are incorporated herein and form part of the specification, illustrate embodiments of the present invention and, together with the description, further serve to explain the principles involved and to enable a person skilled in the relevant art(s) to make and use the disclosed technologies.
The features and advantages of the disclosed technologies will become more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters identify corresponding elements throughout. In the drawings, like reference numbers generally indicate identical, functionally similar, and/or structurally similar elements. The drawing in which an element first appears is indicated by the leftmost digit(s) in the corresponding reference number.
DETAILED DESCRIPTION OF THE INVENTION
- I. Introduction
The following detailed description refers to the accompanying drawings that illustrate example embodiments of the present invention. However, the scope of the present invention is not limited to these embodiments, but is instead defined by the appended claims. Thus, embodiments beyond those shown in the accompanying drawings, such as modified versions of the illustrated embodiments, may nevertheless be encompassed by the present invention.
References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” or the like, indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Furthermore, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to implement such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
Furthermore, it should be understood that spatial descriptions (e.g., “above,” “below,” “up,” “left,” “right,” “down,” “top,” “bottom,” “vertical,” “horizontal,” etc.) used herein are for purposes of illustration only, and that practical implementations of the structures described herein can be spatially arranged in any orientation or manner.
Various approaches are described herein for, among other things, cooling a chip using a flexural plate wave (FPW) device. The cooling techniques described herein are applicable to any suitable type of IC package, including but not limited to wafer level chip scale packages (WLCSPs) and wafer level ball grid array (WLBGA) packages. For example, packages that utilize the cooling techniques described herein may be relatively easy to fabricate, may dissipate heat more effectively than conventional packages, and/or may provide a competitive advantage in technologies that enable very small device features (e.g., 40 nm and lower technologies). Such cooling techniques can also be used as a system-level cooling solution where multiple chips are cooled using one FPW device (or larger numbers of FPW devices). Such techniques may be implemented in any type of commercially available and/or proprietary devices/systems, including stationary devices (e.g., desktop computers, displays (e.g., computer monitors, televisions such as flat panel displays, etc.), mobile devices (e.g., cell phones, smart phones, handheld computers laptop computers, netbooks, tablet computers, handheld music players, etc.), and further types of devices.
- II. Example Chip Cooling Embodiments
Package 100 may be subjected to high temperatures resulting from heat 108. These high temperatures can impair the performance of the circuits of die 102 and/or cause thermal stresses in package 100. Accordingly, a passive cooling device, such as heat sink, may be coupled to die 102 to facilitate further conduction of heat 108 from die 102. However, the mere introduction of passive cooling devices may not adequately dissipate heat 108 from die 102. An active system cooling device, such as a fan, may be used to further dissipate heat 108 from die 102 (e.g., into the air surrounding die 102). However, if package 100 is incorporated in a mobile handheld device, or is used in other limited-space application, it typically is not possible to use a system level cooling fan with regard to package 100. A failure to adequately dissipate heat 108 from die 102 may negatively affect the performance and/or reliability of die 102.
In embodiments, a cooling device that incorporates piezoelectric vibrating structures may be incorporated in package 100 to further dissipate heat 108 from die 102. In an embodiment, the cooling device may be a separate device from die 102 that is attached to die 102. In another embodiment, the cooling device may be integrated with die 102 (e.g., a single-piece die-cooling device combination). In an embodiment, the cooling device may include a flexural plate wave (FPW) device on at least one surface of the cooling device. The FPW device generates a stream of air (e.g., a stream of the gas in the environment in which the cooling device is located) that flows over the surface of the cooling device. The stream of air aids in dissipating heat from the cooling device, which includes at least a portion of heat 108 generated by die 102. In this manner, dies 102 is cooled, which may enable the performance and/or reliability of die 102 to be less negatively affected, even entirely unaffected, by heat 108.
Such cooling devices may be implemented in various ways in embodiments. For instance,
Die 202 has opposing first and second surfaces 224 and 212. First surface 224 is a non-active surface of die 202, and second surface 212 is an active surface of die 202. Die 202 may be formed of various semiconductor materials, such as silicon, gallium arsenide, or other type of semiconductor material. Die 202 may have been separated (singulated) from a semiconductor wafer that includes tens, hundreds, or even larger numbers of dies, and that was processed according to photolithographic and/or other techniques to form integrated circuitry in die 202 (and the other dies) that is accessible at second surface 212.
Electrically conductive interconnect elements 206 are on second surface 212 of die 202. Electrically conductive interconnect elements 206 may be applied to second surface 212 in any manner. Although shown in
In the example of
In the embodiment of
Support members 216A and 216B are coupled between first surface 220 of cooling device 214 and first surface 224 of die 202. Support members 216A and 216B mount cooling device 214 to die 202 and form a gap or channel 226 between die 202 and cooling device 214. Two support members 216A and 216B are shown in
The region between first surface 220 of cooling device 214 and first surface 224 of die 202 may be referred to as channel 226. Channel 226 has a spacing, gap distance, or height defined by a height (length) of support members 216A and 216B. FPW devices 218 (also referred to as piezoelectric vibrating structures or FPW pumps) are coupled to first surface 220 of cooling device 214. Each of the FPW devices 218 is configured to generate a respective traveling wave. The traveling waves act to pump air 222 through channel 226 along surface 220 of cooling device 214 and surface 224 of die 202. The streaming of air 222 along surface 224 of die 202 acts to dissipate at least some of heat 208 that is produced during the operation of die 202 by flowing air along surface 224 of die 202 to receive some of heat 208 in air 222. For instance, the junction temperature Tj that is described with respect to
Although a plurality of FPW devices 218 are shown on first surface 220 of die 202 in
As shown in
As shown in
As shown in
As described above, FPW devices 218 are configured to generate respective traveling waves, which collaboratively pump air 522 along surface 224 of die 202 and surface 220 of cooling device 214 through channel 226 formed between cooling device 214 and die 202. The streaming of air 522 along through channel 226 and along surfaces 220 and 224 acts to dissipate at least some of heat 208 that is produced during the operation of die 202 from die 202 and cooling device 214. Furthermore, the inclusion of recessed region 530 in second surface 228 increases a surface area of second surface 228 of cooling device 214. For example, the increased surface area of surface 228 in
As described above, cooling device 214 may be made of a variety of materials, and may be thermally conductive.
As shown in
Electrical devices that include IC packages with cooling devices may function in various ways to dissipate heat, in embodiments. For instance,
Referring to flowchart 700, in step 702, an integrated circuit (IC) of an electrical device is operated that generates heat during operation. For example, referring to
In step 704, a stream of air is generated with a flexural plate wave device of the electrical device to dissipate at least a portion of the heat generated by the IC die. For example, as shown in
In an embodiment, FPW device 804 is configured to generate a stream of air (e.g., air 222, 322, 422, 522 of
Referring to flowchart 900, in step 902, an acoustic wave is generated that travels through the piezoelectric material that causes the stream of air to flow across the electrical device. For example, referring to
In step 904, the acoustic wave is absorbed to prevent the acoustic wave from reflecting. Step 904 is optional. For example, in an embodiment, wave absorber 808 of
FPW device 804 may be formed and configured in various ways to perform flowcharts 700 and 900, as described above. Various techniques, including micromachining techniques, photolithography, chemical vapor deposition (CVD), vacuum deposition, and/or other techniques may be used to form FPW device 804.
Base layer 1002 may be considered to be part of FPW device 1000, or may be considered to be separate from FPW device 1000. For example, in one embodiment, base layer 1002 may be a layer formed on a body (e.g., body 602 of
As shown in
Dielectric layer 1008 is optionally present. When present, dielectric layer 1008 is coupled to (e.g., attached to or formed on, directly, or indirectly through one or more further layers) diaphragm layer 1006. Dielectric layer 1008 may be formed from one or more electrically insulating layers, including a polymer, a ceramic (e.g., silicon nitride), or other suitable material or combination of materials.
Piezoelectric material layer 1010 is coupled to (e.g., attached to or formed on, directly, or indirectly through one or more further layers) dielectric layer 1008. Piezoelectric material layer 1010 may be formed from one or more piezoelectric materials. Example piezoelectric materials for piezoelectric material layer 1010 include aluminum nitride (AlN), zinc oxide (ZnO), etc.
As shown in
Although a particular configuration for FPW device 1000 is shown in
FPW device 1000 may include any number of layers, including additional, fewer, and/or alternative layers, to implement its functions. Furthermore, the layers of FPW device 1000 may be formed any suitable combination of materials. In one example embodiment, base layer 1002 is made of silicon, support layer 1004 and diaphragm layer 1006 are made of polysilicon, dielectric layer 1008 is made of silicon nitride, and piezoelectric material layer 1110 is made of aluminum nitride.
Wave generator 1014 and wave absorber 1016 may be configured in various ways to perform their respective functions. For instance, as shown in
A first input bond pad 1012a is coupled to base feature 1112, and a second input bond pad 1012b is coupled to base feature 1116. An oscillating voltage source 1102 is coupled to first and second input bond pads 1012a and 1012b such that a first oscillating signal 1128 is coupled to first comb-shaped electrically conductive feature 1104, and a second oscillating signal 1130 is coupled to second comb-shaped electrically conductive feature 1106. Oscillating voltage source 1102 generates first and second oscillating signals 1128 and 1130 to generate an electric field with first and second comb-shaped electrically conductive features 1104 and 1106. The electric field causes piezoelectric material layer 1010 to vibrate to form an acoustic wave 1134 in piezoelectric material layer 1010, dielectric layer 1008, and diaphragm layer 1006 that travels in the direction of direction 1026.
For instance, oscillating voltage source 1102 may generate first and second oscillating signals 1128 and 1130 to be out of phase (e.g., opposite phase or 180 degrees out of phase) to generate the electric field to be oscillating. The oscillating electric field may cause piezoelectric material layer 1010 to vibrate to generate acoustic waves 1134 as Rayleigh waves, as are known to persons skilled in the relevant art(s). A velocity of Rayleigh waves depends on factors that include the type of piezoelectric material of piezoelectric material layer 1010. If zinc oxide is used as the piezoelectric material, the Rayleigh velocity is about 4 times lower. Hence, with zinc oxide, the frequency of oscillation is also 4 times lower for a same inter-digitated finger spacing of wave generator 1014. When the piezoelectric material is selected, a basic pumping velocity (speed of wave propagation through diaphragm layer 1006) is thereby selected. The actual pumping velocity is then the function of the height of channel 226 (when a channel is present), the amplitude of the acoustic wave (for transfer effect), and a velocity profile across the channel (a function of the air being pumped), as would be known to persons skilled in the relevant art(s) from the teachings herein.
In one embodiment, the Rayleigh wave velocity for the piezoelectric material of piezoelectric material layer 1010 may be used to determine a frequency of oscillating signals 1128 and 1130. Equation 1 shown below indicates a relationship between the Rayleigh wave velocity (CR), wavelength (λ), and oscillating voltage frequency (ƒ):
CR=λ׃ Equation 1
For instance, if wavelength λ is 0.00001 meters, and the Rayleigh wave velocity is 10.4 km/sec (e.g., for AlN piezoelectric material in a particular configuration), frequency ƒ may be determined to be 10.4 km/sec/0.00001 meters=1040 MHz. Thus, for a spacing of d=0.000005 meters, and a piezoelectric material of AlN, oscillating signals 1128 and 1130 may be generated to have frequencies of 1040 MHz.
Note that the amplitude of the vibration of piezoelectric material layer 1010 and diaphragm layer 1006 may be selected based on various factors. For instance,
Note that the piezoelectric efficiency of conversion of voltage to vibration depends on these and various other factors, including the type of piezoelectric material, a crystallographic orientation of the crystals of the piezoelectric material, and a quality of the piezoelectric films.
Referring back to
Wave absorber 1016 is configured to at least reduce a reflection of acoustic waves 1134 through piezoelectric material layer 1010 (and diaphragm layer 1006 of
For example,
Note that other configurations for wave generator 1014 and wave absorber 1016 than shown in
According to embodiments, acoustic streaming is air flow caused by high frequency travelling waves. Acoustic streaming is caused by friction between the medium (e.g., the air) and the vibrating wall (e.g., a diaphragm that vibrates due to one or more FPW devices). Acoustic streaming creates a flow pattern that includes the following effects: (a) convective heat transfer enhancement (vortex type air-flow effect), and (b) an increase in flow velocity (pumping effect). With regard to the pumping effect, a flow rate of air in the vicinity of the vibrating diaphragm is directly proportional to the velocity of the travelling wave. The higher the velocity, the greater is the pumping of air. The actual flow-rate depends on a mean velocity in the channel.
ΘJA=(TJ−TA)/device power Equation 2
where
-
- TJ=junction temperature,
- TA=ambient temperature, and
- device power=die active surface power.
Graph 2000 includes plots 2002 and 2004. Plot 2002 represents junction-to-ambient thermal resistances for an electrical device that does not include a cooling device or FPW devices. As depicted by plot 2002, the junction-to-ambient thermal resistance for an electronic device that does not include a cooling device/FPW device remains substantially constant at approximately 100% for wave travel velocities from 0 m/s to 100 m/s. Plot 2004 represents junction-to-ambient thermal resistances for an electrical device that does include a cooling device and FPW device. As depicted by plot 2004, the junction-to-ambient thermal resistance for an electrical device that does include a cooling device and FPW devices decreases from approximately 96.8% at a wave travel velocity of approximately 0 m/s to approximately 67.9% at a wave travel velocity of approximately 100 m/s. The slope of plot 2004 is more negative between wave travel velocities of 0 m/s to approximately 20 m/s than between wave travel velocities of approximately 20 m/s to 100 m/s. The slope of plot 2004 is shown to be substantially linear between wave travel velocities of approximately 20 m/s to 100 m/s. Accordingly, cooling devices with FPW devices offer substantial reductions in junction-to-ambient (die-to-ambient) thermal resistance for electrical devices, particularly as wave travel velocity is increased for an FPW device.
In an embodiment, an electrical device includes an integrated circuit die (IC) having opposing first and second surfaces, a plurality of interconnects on the second surface of the IC die that enable the IC die to be coupled to a substrate, and a flexural plate wave device configured to generate a stream of air to flow across the electrical device to cool the IC die during operation of the IC die.
The flexural plate wave device may be on the first surface of the IC die.
The electrical device may further include a cooling device having opposing first and second surfaces, wherein the cooling device is coupled to the IC die, and the flexural plate wave device is on the first surface of the cooling device.
The electrical device may further include a plurality of support members coupled between the first surface of the cooling device and the first surface of the IC die that mount the cooling device to the IC die and form a channel between the IC die and the cooling device, wherein the stream of air generated by the flexural plate wave device flows through the channel.
The second surface of the cooling device may have a recessed region.
The second surface of the cooling device may be attached to the first surface of the IC die, wherein the stream of air generated by the flexural plate wave device flows across the first surface of the cooling device.
The flexural wave plate device may include a base layer, a support layer coupled to the base layer, a diaphragm layer coupled to the support layer, the support layer including an opening to form an air gap between the base layer and the diaphragm layer, a piezoelectric material layer coupled to the diaphragm layer, and a wave generator formed on the piezoelectric material layer that is configured to generate an acoustic wave that travels through the piezoelectric material layer, the acoustic wave causing the stream of air to flow across the electrical device.
The wave generator may include a first comb-shaped electrically conductive feature, and a second comb-shaped electrically conductive feature electrically isolated from and interlocked with the first comb-shaped electrically conductive feature, wherein a first oscillating signal is coupled to the first comb-shaped electrically conductive feature, and a second oscillating signal is coupled to the second comb-shaped electrically conductive feature.
The electrical device may further include a wave absorber formed on the piezoelectric material layer configured to receive and absorb the acoustic wave to at least reduce a reflection of the acoustic wave through the piezoelectric material layer.
The wave absorber may include a first comb-shaped electrically conductive feature, and a second comb-shaped electrically conductive feature interlocked with the first comb-shaped electrically conductive feature.
The second comb-shaped electrically conductive feature may be electrically coupled to the first comb-shaped electrically conductive feature.
In another embodiment, a cooling device includes a body that has opposing first and second surfaces, and a flexural plate wave device on the first surface that is configured to generate a stream of air to flow at least across the cooling device to cool an integrated circuit (IC) during operation of the integrated circuit (IC).
The body may be an IC die, and the second surface may be an active surface of the IC die.
The cooling device may include a plurality of support members on the first surface of the cooling device configured to mount the cooling device to an IC die and form a channel between the IC die and the cooling device, wherein the stream of air generated by the flexural plate wave device flows through the channel.
The second surface of the cooling device may be a recessed region.
The second surface of the cooling wave device may be configured to be attached to an IC die.
The flexural plate wave device may include a support layer coupled to the body, a diaphragm layer coupled to the support layer, the support layer including an opening to form an air gap between the body and the diaphragm layer, a piezoelectric material layer coupled to the diaphragm layer, and a wave generator formed in contact with the piezoelectric material layer that is configured to generate an acoustic wave that travels through the piezoelectric material layer, the acoustic wave causing the stream of air to flow at least across the cooling device.
The wave generator may include a first comb-shaped electrically conductive feature, and a second comb-shaped electrically conductive feature electrically isolated from and interlocked with the first comb-shaped electrically conductive feature, wherein a first oscillating signal is coupled to the first comb-shaped electrically conductive feature, and a second oscillating signal is coupled to the second comb-shaped electrically conductive feature.
The cooling device may include a wave absorber formed in contact with the piezoelectric material layer configured to receive and absorb the acoustic wave to prevent the acoustic wave from reflecting through the piezoelectric material layer.
In a further embodiment, a method includes operating an integrated circuit (IC) of an electrical device that generates heat during operation, and generating a stream of air with a flexural plate wave device of the electrical device to dissipate at least a portion of the heat generated by the IC die.
CONCLUSIONWhile various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.
Claims
1. An electrical device, comprising:
- an integrated circuit (IC) die having opposing first and second surfaces;
- a plurality of interconnects on the second surface of the IC die that enable the IC die to be coupled to a substrate;
- a flexural plate wave device configured to generate an acoustic wave through at least a portion of the flexural plate wave device, the acoustic wave causing vortexes of air to be pumped across the electrical device to cool the IC die during operation of the IC die.
2. The electrical device of claim 1, wherein the flexural plate wave device is on the first surface of the IC die.
3. The electrical device of claim 1, further comprising:
- a cooling device having opposing first and second surfaces, wherein the cooling device is coupled to the IC die, and the flexural plate wave device is on the first surface of the cooling device.
4. The electrical device of claim 3, further comprising:
- a plurality of support members coupled between the first surface of the cooling device and the first surface of the IC die that mount the cooling device to the IC die and form a channel between the IC die and the cooling device;
- wherein the vortexes of air are pumped through the channel.
5. The electrical device of claim 4, wherein the second surface of the cooling device has a recessed region.
6. The electrical device of claim 3, wherein the second surface of the cooling device is attached to the first surface of the IC die;
- wherein the vortexes of air flow across the first surface of the cooling device.
7. The electrical device of claim 1, wherein the flexural plate wave device comprises:
- a base layer;
- a support layer coupled to the base layer;
- a diaphragm layer coupled to the support layer, the support layer including an opening to form an air gap between the base layer and the diaphragm layer;
- a piezoelectric material layer coupled to the diaphragm layer; and
- a wave generator formed on the piezoelectric material layer that is configured to generate the acoustic wave.
8. The electrical device of claim 7, wherein the wave generator comprises:
- a first comb-shaped electrically conductive feature; and
- a second comb-shaped electrically conductive feature electrically isolated from and interlocked with the first comb-shaped electrically conductive feature;
- wherein a first oscillating signal is coupled to the first comb-shaped electrically conductive feature, and a second oscillating signal is coupled to the second comb-shaped electrically conductive feature.
9. The electrical device of claim 7, further comprising:
- a wave absorber formed on the piezoelectric material layer configured to receive and absorb the acoustic wave to at least reduce a reflection of the acoustic wave through the piezoelectric material layer.
10. The electrical device of claim 9, wherein the wave absorber comprises:
- a first comb-shaped electrically conductive feature; and
- a second comb-shaped electrically conductive feature interlocked with the first comb-shaped electrically conductive feature.
11. The electrical device of claim 10, wherein the second comb-shaped electrically conductive feature is electrically coupled to the first comb-shaped electrically conductive feature.
12. A cooling device, comprising:
- a body that has opposing first and second surfaces; and
- a flexural plate wave device on the first surface that is configured to generate an acoustic wave through at least a portion of the flexural plate wave device, the acoustic wave causing vortexes of air to be pumped across the cooling device to cool an integrated circuit (IC) during operation of the integrated circuit (IC).
13. The cooling device of claim 12, wherein the body is an IC die, and the second surface is an active surface of the IC die.
14. The cooling device of claim 12, further comprising:
- a plurality of support members on the first surface of the body configured to mount the cooling device to an IC die and form a channel between the IC die and the cooling device;
- wherein the vortexes of air are pumped through the channel.
15. The cooling device of claim 14, wherein the second surface of the body has a recessed region.
16. The cooling device of claim 12, wherein the second surface of the body is configured to be attached to an IC die.
17. The cooling device of claim 12, wherein the flexural plate wave device comprises:
- a support layer coupled to the body;
- a diaphragm layer coupled to the support layer, the support layer including an opening to form an air gap between the body and the diaphragm layer;
- a piezoelectric material layer coupled to the diaphragm layer; and
- a wave generator formed in contact with the piezoelectric material layer that is configured to generate the acoustic wave.
18. The cooling device of claim 17, wherein the wave generator comprises:
- a first comb-shaped electrically conductive feature; and
- a second comb-shaped electrically conductive feature electrically isolated from and interlocked with the first comb-shaped electrically conductive feature;
- wherein a first oscillating signal is coupled to the first comb-shaped electrically conductive feature, and a second oscillating signal is coupled to the second comb-shaped electrically conductive feature.
19. The cooling device of claim 17, further comprising:
- a wave absorber formed in contact with the piezoelectric material layer configured to receive and absorb the acoustic wave to prevent the acoustic wave from reflecting through the piezoelectric material layer.
20. A method, comprising:
- operating an integrated circuit (IC) of an electrical device that generates heat during operation; and
- generating an acoustic wave with a flexural plate wave device of the electrical device, the acoustic wave causing vortexes of air to be pumped across the electrical device to cool the IC during operation of the IC.
Type: Application
Filed: Jul 16, 2015
Publication Date: Nov 5, 2015
Inventors: Milind S. Bhagavat (Fremont, CA), Mehdi Saeidi (Irvine, CA), Tak Sang Yeung (Irvine, CA)
Application Number: 14/801,377