Patent Publication Number: US-11652080-B2

Title: Thermal compression bonder nozzle with vacuum relief features

Description:
BACKGROUND 
     Thermal compression bonding (TCB) tools may be employed in die attach operations during the package assembly of integrated circuit (ICs). Such tools may comprise a vacuum nozzle to hold a die in place by vacuum clamping the die to the nozzle. Alignment of the die with a substrate may be maintained by the vacuum nozzle, as the die is pressed against the substrate and held together between heated platens to which a mild compression force is applied. The aligned die and substrate are heated to enable reflow of first level interconnect (FLI) solder bumps on die or substrate. While securely clamped in place by the vacuum nozzle, the die undergoes bonding to the substrate as platens are heated to solder liquidus temperatures. Solder bumps on the die and/or substrate reflow to form FLI solder joints between die and substrate as the platens cool below reflow temperatures. 
     While the die may be securely clamped by the vacuum nozzle during the reflow operation, the alignment accuracy between die and substrate interconnects may be degraded by non-uniform thermal expansion and contraction of the die relative to the substrate during the reflow operation. The non-uniform thermal expansion and contraction of the die may be caused by pinning of the die at corners and edges of the vacuum nozzle by strong vacuum, constraining normal thermal expansion of the die while the substrate undergoes free thermal expansion. As a result, there may be a misalignment of die and substrate interconnects before and during FLI reflow, which may worsen with larger dies. The offset between interconnect centers may be as much as 10 microns. In addition, pinning of the die during heating may cause die warpage leading to large gaps, as much as 15 microns, in the bonding plane between die and substrate and non-bonded contacts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  illustrates a cross-sectional view in the x-z plane of a vacuum bonding nozzle according to some embodiments of the disclosure. 
         FIG.  1 B  illustrates a profile view in the y-z plane of a vacuum bonding nozzle according to some embodiments of the disclosure. 
         FIG.  1 C  illustrates a plan view in the x-y plane of a vacuum bonding nozzle according to some embodiments of the disclosure. 
         FIG.  2 A  illustrates a cross-sectional view in the x-z plane of a bonding nozzle employed in a thermal compression bonder, according to some embodiments of the disclosure. 
         FIG.  2 B  illustrates a cross-sectional view in the y-z plane of a bonding nozzle employed in a thermal compression bonder, according to some embodiments of the disclosure. 
         FIG.  3    illustrates a plan view in the x-y plane of a vacuum bonding nozzle, showing vacuum gradients within the channel network on a bonding surface when coupled to an active vacuum pump, according so some embodiments of the disclosure. 
         FIG.  4    illustrates a process flow chart for using the disclosed vacuum bonding nozzle according to some embodiments of the disclosure. 
         FIG.  5    illustrates a block diagram of a computing device as part of a system-on-chip (SoC) package in an implementation of one or more integrated circuit dies attached to a substrate in a thermal compression bonder employing a vacuum bonding nozzle according to some embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein is a vacuum bonding nozzle for use in thermal compression bonding tools. According to some embodiments, the vacuum bonding nozzle comprises vacuum relief conduits on the periphery of its bonding surface to weaken the vacuum seal and clamping of the peripheral regions of a die, while maintaining adequate seal and clamping force in the interior regions of the die to hold the die firmly against the bonding surface of the nozzle to maintain alignment between a die and a substrate during die attachment operations. The disclosed vacuum bonding nozzle may mitigate pinning of the periphery of the die against the bonding surface of the vacuum bonding nozzle, enabling free thermal expansion and contraction of the die during the reflow phase of the die attach process. The disclosed vacuum bonding nozzle may thus enable the die to expand and contract in phase with the substrate, mitigating first-level interconnect (FLI) misalignment. Peripheral pinning may also cause warpage of the die, leading to gaps between die and substrate, with non-bonded contacts. Reduction of peripheral clamping forces by employment of the disclosed bonding nozzle in die attach processes may also reduce gaps in the bonding plane by mitigation of die warpage from constrained thermal expansion. 
     The disclosed vacuum bonding nozzle comprises a bonding surface comprising a network of interconnected channels. The network of channels includes a first channel portion comprising interior channels within a central portion of the bonding surface, and a second channel portion comprising peripheral channels extending along the periphery of the bonding surface. The peripheral channels may be joined to interior channels extending to the center of the bonding surface. Interior channels may intersect a central conduit extending perpendicularly from the bonding surface through the vacuum bonding nozzle, terminating at a vacuum port at the top of the vacuum bonding nozzle. The interior channels couple the peripheral channels to the vacuum conduit, which may be coupled to a vacuum source. In some embodiments, the bonding surface has a rectangular footprint. Peripheral channels may extend along each of the four orthogonal edges of the bonding surface. Adjacent ends of the peripheral channels may be joined to each other to form a contiguous ring around the perimeter of the bonding surface. 
     Vacuum relief conduits intersect and open into one or more peripheral channels near the corners of the bonding surface. The vacuum relief conduits may be machined into the body of the vacuum bonding nozzle, extending to one or more walls of the vacuum bonding nozzle. The vacuum relief conduits may open to an ambient atmosphere surrounding the bonding nozzle. One vacuum relief conduit may intersect a peripheral channel near an end of the channel, for example, near the corners of the bonding surface. In some embodiments, one or more of the peripheral channels on a rectangular bonding surface may be each intersected by a first vacuum relief conduit at a first end, and by a second vacuum relief conduit at a second end. In some embodiments, a third vacuum relief conduit may intersect one or more of the peripheral channels between the first and second vacuum relief conduits. 
     The vacuum relief conduits provide controlled vacuum leaks (e.g., air or other ambient atmosphere leaks into the nozzle). The controlled vacuum leaks through the vacuum relief conduits enable a vacuum gradient to form within the channel network when the vacuum bonding nozzle is connected to a vacuum source, such as an active vacuum pump. The vacuum may be weakest (e.g., the gas pressure highest) within the peripheral channels due to the to the vacuum relief conduits being fluidically coupled to one or more of the peripheral channels. Thus, the clamping force of the disclosed vacuum bonding nozzle along the periphery of an IC die to which the bonding nozzle is engaged may be significantly smaller than the clamping force on the central portion of the die. 
     By establishment of a radial or other vacuum gradient within the channel network enables a distribution of clamping force on the IC die. As an example, a vacuum gradient may be formed within the first and second channel portions such that the clamping force on an engaged IC die may be highest within a central region of an IC die interfaced to the bonding surface. The central clamping force may be sufficient to prevent movement of the IC die during alignment with a package substrate and subsequent temperature cycling for solder reflow. While vacuum clamping may be strongest within a central region of the bonding surface and IC die. The vacuum clamping force may diminish in a radial manner within the interior channels as they approach the peripheral channels. As a result, clamping forces may be lowest at the periphery of the boding surface, enabling the peripheral regions of the IC die to undergo relatively unrestrained thermal expansion in response to temperature cycling (e.g., for solder reflow). 
     With a conventional bonding nozzle, vacuum clamping forces may not be distributed in a gradient (e.g., in a radial manner), whereby clamping forces at the periphery of the bonding surface are substantially the same as clamping forces within the central region of the bonding surface, enabling pinning of peripheral regions of the IC die. Natural thermal expansion and contraction of the IC die may be prevented or impeded during a heating and cooling cycles, for example, in a thermal compression bonding tool. Two consequences may occur as a result. First, the substrate may not be so constrained and may be free to expand, creating a misalignment between die and substrate. Offsets as large as 10 microns between die and substrate interconnects. Second, while the die is constrained from expanding laterally, significant transverse buckling and warpage may occur, whereby significant gaps may develop between die and substrate. Such gaps may create non-bonded states for some interconnects as die interconnects are raised well above substrate contacts. 
     Views labeled “cross-sectional”, “profile”, “plan”, and “isometric” correspond to orthogonal planes within a cartesian coordinate system. Thus, cross-sectional and profile views are taken in the x-z plane, plan views are taken in the x-y plane, and isometric views are taken in a 3-dimensional cartesian coordinate system (x-y-z). Where appropriate, drawings are labeled with axes to indicate the orientation of the figure. 
       FIG.  1 A  illustrates a cross-sectional view in the x-z plane of vacuum bonding nozzle  100  according to some embodiments of the disclosure. 
     Vacuum bonding nozzle  100  comprises body  101 , machined or cast into suitable shapes such as the T-shaped profile shown in the figure. Body  101  may comprise metals such as copper, steel, brass and aluminum, or any suitable material that may withstand solder reflow temperatures (e.g., temperatures exceeding 200°-250° C.). In some embodiments, body  101  comprises stage  102  and base  103 . Stage  102  may have a substantially larger width w 1  than base w 2 , and may overhang sidewalls of base  103 . A larger width w 1  of stage  102  (with respect to width w 2 ) may enable even distribution of forces from heating platen  104  when engaged with upper surface  105  of stage  102  (it will be understood that platen  104  is not a part of vacuum bonding nozzle  100 , but is shown for context). Peripheral channel  106  extends within lower bonding surface  107 , and may extend along most of width w 2  of base  103 . As shown below, peripheral channel  106  extends along the perimeter of base  103 . 
     In the illustrated embodiment, vacuum relief conduits  108  and  109  intersect peripheral channel near each end. A third vacuum relief conduit  110  may optionally intersect peripheral channel  106  between vacuum relief conduits  108  and  109 . For example, vacuum relief conduit  110  may intersect peripheral channel  106  near the center, as shown. Orifices  111  are the openings of vacuum relief conduits  108 ,  109  and  110  into peripheral channel  106 . Vacuum relief conduits  108 ,  109  and  110  may rise vertically (in the z-direction) above bonding surface  107 . Vacuum relief conduits may also include horizontal portions  112  and  113  extending laterally (in the x-direction) to opposing walls  114  and  115 , respectively. Middle vacuum relief conduit  110  may also has a horizontal portion (not shown) that extends along the y-axis of the figure, above and below the plane of the figure. Horizontal portions  112  and  113  intersect opposing walls  114  and  115 , forming orifices  116  and  117  at the planes of intersection, whereby orifices  116  and  117  open to ambient atmosphere  118  (indicated by the dashed enclosure) that surrounds vacuum bonding nozzle  100 . 
     In some embodiments, horizontal portions  112  and  113  may intersect the same wall (e.g., wall  114 ) or orthogonal walls. In some embodiments, horizontal portions  112  and  113  may also intersect walls of base  103 , it may be advantageous to locate orifices  116  and  117  at the furthest possible distance from bonding surface  107  to avoid pulling solder and flux vapors into the vacuum system. 
       FIG.  1 B  illustrates a rotated profile view of vacuum bonding nozzle  100  in the y-z plane, according to some embodiments of the disclosure. 
     The profile view of vacuum bonding nozzle  100  is rotated 90° to the y-z plane to show orifices  116  at planes of intersection of horizontal portions  112  vacuum relief conduits with sidewall  114 . Hidden lines indicate positions of a peripheral channel extending along bonding surface  107  parallel to sidewall  114  and vacuum relief conduits (e.g., vacuum relief conduits  108 ) within body  101  that terminate at orifices  116  on sidewall  114 . In some embodiments, stage  102  and base  103  have a rectangular footprint. As shown in  FIGS.  1 A and  1 B , both stage  102  and base  103  have shorter widths w 3  and w 4 , respectively, along the y-axis than along the x-axis. (e.g., w 1 &gt;w 3 , w 2 &gt;w 4 ). 
       FIG.  1 C  illustrates a plan view in the x-y plane of vacuum bonding nozzle  100  according to some embodiments of the disclosure. 
     Peripheral channels  106 ,  119 ,  120  and  121  extend along the periphery of bonding surface  107 , having edges that coincide with sidewalls  122 ,  123 ,  124  and  125  of base  103 . In the illustrated embodiment, ends of peripheral channels  119  and  121  on opposing edges of bonding surface  107  join ends of orthogonal peripheral channels  106  and  120 , forming a contiguous ring channel extending along the perimeter of bonding surface  107 . Interior channels  126 ,  127 ,  128  and  129  extend in a radial configuration between the center and the periphery of bonding surface  107 . In the illustrated embodiment, each of interior channels  126 - 129  opens into vacuum conduit  130  at a first end. Channels of the channel network may be grooves milled or otherwise engraved into bonding surface  107 , recessed to a depth of 0.1 to 2 millimeters from the plane of bonding surface  107 . The channels may have any suitable cross section width. In some embodiments, interior channels  126 - 129  may have a tapered cross section, as described below. 
     While interior channels  126 - 129  are shown in the illustrated embodiment extending in a radial geometry to the corners of bonding surface  107 , other suitable geometries may be considered for extending interior channels  126 - 129  to intersect with peripheral channels  106 ,  119 ,  120  and  121 . While interior channels  126 - 129  are shown to have a constant channel cross section in the illustrated embodiment, in some embodiments interior channels  126 - 129  may have a tapered cross section, for example, having a wide cross section at the intersection with peripheral channels, and a narrow cross section at the intersection with central vacuum conduit  130 . A taper within the channel cross section may create a venturi effect with interior channels  126 - 129 , potentially enhancing vacuum gradients created when the bonding nozzle is coupled to an active vacuum source. In some embodiments, a taper may be engineered for optimal distribution of clamping forces on an engaged IC die. 
     Vacuum conduit  130  terminates at an orifice at the center of bonding surface  107 . Vacuum conduit  130  may extend vertically (e.g., in z-direction perpendicular to the figure) from bonding surface  107 , through base  103  to the upper surface of stage  102  (e.g., upper surface  105  in  FIG.  1 A ). Interior channels  126 - 129  extend radially, each toward a corner region of bonding surface  107 . Interior channels  126 - 129  may join peripheral channels  106 ,  119 ,  120  and  121  at or near their points of intersection, for example, near the corners of bonding surface  107 . 
     The network of bonding nozzle channels comprising interior channels  126 - 129  and peripheral channels  106 ,  119 - 121  are coupled to vacuum conduit  130 . Vacuum relief conduits (e.g., vacuum relief conduits  108 - 110 ) open into peripheral channels  106  and  120 , forming orifices  111  and  131 . The vacuum relief conduits may enable controlled leakage of air or other atmospheric gases for vacuum relief along peripheral channels  106  and  120 . Vacuum relief conduits may also terminate at other peripheral channels. In some embodiments, only one or two vacuum relief conduits may intersect each peripheral channel. For example, one vacuum relief conduit may intersect a peripheral channel at an end or between ends. 
       FIG.  2 A  illustrates a cross-sectional view in the x-z plane of bonding nozzle  100  employed in thermal compression bonder  200 , according to some embodiments of the disclosure. 
     The cross-sectional view plane of thermal compression bonder  200  cuts through peripheral channel  106 . Thermal compression bonder  200  comprises upper and lower heating platens  201  and  202 , which may be engaged by a vise-like mechanism within bonder  200  (not shown) for pressing heating platens  201  and  202  together. In the illustrated embodiment, die  203  is aligned with substrate  204  such that solder bumps  205  align to die interconnects  206  or substrate interconnects  207 . Platens  201  and  202  may be heated (indicated by wavy arrows showing direction of heat flow) to reflow solder bumps  205  to form FLI solder joints between die interconnect  206  and substrate interconnects  207 . Die  203  may be vacuum clamped to bonding surface  107  of bonding nozzle  100 . A vacuum may be applied to bonding nozzle  100  by engaging upper platen  201  with top surface  105  of stage  102 , where a seal may be formed between vacuum port  208  on upper platen  201  and a central vacuum conduit (e.g., vacuum conduit  130 ) extending through base  103  and stage  102  of bonding nozzle  100 . coupling bonding nozzle  100  to a vacuum system through vacuum port  208 . 
     Peripheral conduit  106  may be coupled to vacuum port  208  through the channel network on bonding surface  107 , as illustrated in  FIG.  1 C . The channel network comprises peripheral channels (e.g., peripheral channel  106 ,  119 - 121 ) extending around the perimeter of bonding surface  107  and interior channels (e.g., interior channels  126 - 129 ,  FIG.  1 C ) extending between vacuum conduit (e.g., vacuum channel  130 ) and peripheral channels (e.g., peripheral channels  106 ,  119 - 121 ). 
     Vacuum relief conduits  108 ,  109  and  110  open into peripheral channel  106  through orifices  111 . When a vacuum pump is coupled to the channel network through vacuum port  208 , air flows out of vacuum port  208 , as indicated by the vertical arrow pointing away from vacuum port  208 . A continuous flow may be established, whereby air or other ambient gases may leak into peripheral channel  106  through openings  116  and  117  on sidewalls  114  and  115 . The vacuum flow is indicated by the horizontal arrows pointing into openings  116  and  117 . 
       FIG.  2 B  illustrates a cross-sectional view in the y-z plane of bonding nozzle  100  employed in thermal compression bonder  200 , according to some embodiments of the disclosure. 
     Thermal compression bonder  200  is rotated 90° to show another cross-sectional view taken through a central y-z plane. Central vacuum conduit  130  is shown extending from bonding surface  107 , where it exerts the greatest suction force on die  203 , through vacuum port  208 /While not shown in the cross-sectional view, vacuum conduit  130  is coupled through interior channels (e.g., interior channels  126  and  129 ) to peripheral channels  106  and  120 , extending along opposite sidewalls  122  and  124 . 
     Vacuum conduit  130  may be coupled to the vacuum system of the thermal compression bonder tool, which may be coupled to an external vacuum pump (not shown). 
       FIG.  3    illustrates a plan view in the x-y plane of vacuum bonding nozzle  100 , showing vacuum gradients within the channel network on bonding surface  107  when coupled to a vacuum source, according so some embodiments of the disclosure. 
     During a die attach process for example, vacuum gradients may be established within the channel network comprising peripheral channels  106 ,  119 - 121  and interconnected interior channels  126 - 129 . Vacuum gradients are indicated by shading gradations within interior channels  126 - 129 , where black indicates the strongest vacuum and white indicates the weakest vacuum, with shades of gray indicating intermediate levels of vacuum. As shown, the vacuum is strongest at the center of bonding surface  107 , particularly within vacuum channel  130 . The vacuum gradient extends laterally within interior channels  126 - 129  and weakens as it approaches the periphery of bonding surface  107 . As shown, vacuum gradients may not occur within peripheral channels  106 ,  119 - 121 . Air or other ambient gases may enter peripheral channels through orifices  111  and  131  where vacuum relief conduits open into the peripheral channels. Air may fill the peripheral channels while flowing up the four interior channels toward vacuum conduit  130  at the center of bonding surface  107 . 
     Vacuum relief conduits (e.g., vacuum relief conduits  108 ) may be dimensioned to produce small air leakage into the peripheral channels. For example, the diameters of orifices  111  and  131  (and diameters of vacuum relief conduits also) may be dimensioned to permit a leakage rate that approximates the vacuum flow rate. The vacuum may also be adjusted to attain an air leakage rate that enables formation of a vacuum gradient within the channel network such as that shown in  FIG.  3     
     The vacuum gradient shown in  FIG.  3    may provide sufficient clamping force in the central portion of a die (e.g., die  203 ) engaged by vacuum bonding nozzle  100 , as shown in  FIG.  2   , to prevent lateral displacement. Clamping force at the periphery of the die may be significantly weaker relative to the central portion of the die, as a consequence of the low vacuum within peripheral channels. As a result, pinning of corners and edges of the die may be substantially mitigated, enabling unrestrained thermal expansion and contraction of the edges and corners of the die according to the temperature cycle phase imposed by the thermal compression bonder. 
     Lateral misalignment of die and substrate interconnects may be significantly mitigated. For example, bump misalignment may be reduced by an average of 10 microns in comparison to displacements when a conventional bonding nozzle is employed in the die attach process. Similarly, warpage of the die and formation of FLI gaps between die and substrate may also be substantially mitigated. For example, a reduction of gap variation by an average of 15 microns may be obtained relative to observed gap variation when employing conventional bonding nozzles not having the disclosed vacuum relief conduits. The improvements in FLI alignment realized by including vacuum relief features such as vacuum relief conduits as descried above may result in higher product yields than would be possible with a conventional vacuum bonding nozzle. 
       FIG.  4    illustrates process flow chart  400  for using the disclosed vacuum bonding nozzle according to some embodiments of the disclosure. 
     At operation  401 , a die is prepared for bonding to a package substrate. The die and and/or individual substrate may be bumped with solder on all interconnects, and placed in a thermal compression bonder tool as shown in  FIG.  2   . The die (e.g., die  203 ) is brought in contact with a vacuum bonding nozzle having vacuum relief features (e.g., bonding nozzle  100 ), according to embodiments described above. The die may be pressed against the bonding surface of the vacuum bonding nozzle. A jig may be employed to immobilize the die and substrate pair. 
     The die may be pre-aligned with an individual package substrate (e.g., substrate  204 ), where both package and die are held in proximity of one another in an alignment jig. Precise alignment between die and substrate may be achieved by automated pick-and-place operations. Alignment may also be performed at wafer level, where multiple unsingulated substrate chips carried on a wafer or panel may be aligned with individual IC dies by automated placement processes. 
     At operation  402 , the die and substrate may be placed in a jig that is set between two heating platens (e.g., upper and lower platens  201  and  202 ) of a thermal compression bonder tool. Upper and lower heating platens may be moved toward each other, compressing the die and substrate against each other with mild force. A vacuum source may be coupled to a vacuum bonding nozzle (e.g., through vacuum port  208 ) coupled to the channel network of the vacuum bonding nozzle, creating a vacuum with the channel network to securely clamp the die to the bonding nozzle. 
     As vacuum relief conduits enable air leakage into the channel network, a vacuum gradient may be established within the channel network. The vacuum gradient may be established such that the vacuum may increase inwardly from the periphery toward the center of the bonding nozzle. Peripheral channels may carry a relatively weak vacuum such that clamping forces. As noted above, clamping forces at the periphery of the die may be weaken so as not to pin the corners and edges of the die against the bonding surface, enabling unconstrained thermal expansion and contraction of the die. Alignment between die and substrate interconnects may be substantially maintained as described above. 
       FIG.  5    illustrates a block diagram of computing device  500  as part of a system-on-chip (SoC) package in an implementation of one or more integrated circuit dies attached to a substrate in a thermal compression bonder employing a vacuum bonding nozzle according to some embodiments of the disclosure. 
     According to some embodiments, computing device  500  represents a server, a desktop workstation, or a mobile workstation, such as, but not limited to, a laptop computer, a computing tablet, a mobile phone or smart-phone, a wireless-enabled e-reader, or other wireless mobile device. 
     In some embodiments, computing device has wireless connectivity (e.g., Bluetooth, WiFi and 5G network). It will be understood that certain components are shown generally, and not all components of such a device are shown in computing device  500 . 
     The various embodiments of the present disclosure may also comprise a network interface within  570  such as a wireless interface so that a system embodiment may be incorporated into a wireless device, for example, cell phone or personal digital assistant. The wireless interface includes a millimeter wave generator and antenna array. The millimeter wave generator may be part of a monolithic microwave integrated circuit. 
     According to some embodiments, processor  510  represents a CPU or a GPU, and can include one or more physical devices, such as microprocessors, application processors, microcontrollers, programmable logic devices, or other processing means. Processor  510  may be coupled to a memory controller or high-speed serial I/O interface controller, as disclosed. The processing operations performed by processor  510  include the execution of an operating platform or operating system on which applications and/or device functions are executed. The processing operations include operations related to I/O (input/output) with a human user or with other devices, operations related to power management, and/or operations related to connecting the computing device  500  to another device. The processing operations may also include operations related to audio I/O and/or display I/O. 
     In one embodiment, computing device  500  includes audio subsystem  520 , which represents hardware (e.g., audio hardware and audio circuits) and software (e.g., drivers, codecs) components associated with providing audio functions to the computing device. Audio functions can include speaker and/or headphone output, as well as microphone input. Devices for such functions can be integrated into computing device  500 , or connected to the computing device  500 . In one embodiment, a user interacts with the computing device  500  by providing audio commands that are received and processed by processor  510   
     Display subsystem  530  represents hardware (e.g., display devices) and software (e.g., drivers) components that provide a visual and/or tactile display for a user to interact with the computing device  500 . Display subsystem  530  includes display interface  532  which includes the particular screen or hardware device used to provide a display to a user. In one embodiment, display interface  532  includes logic separate from processor  510  to perform at least some processing related to the display. In one embodiment, display subsystem  530  includes a touch screen (or touch pad) device that provides both output and input to a user. 
     I/O controller  540  represents hardware devices and software components related to interaction with a user. I/O controller  540  is operable to manage hardware that is part of audio subsystem  520  and/or display subsystem  530 . Additionally, I/O controller  540  illustrates a connection point for additional devices that connect to computing device  500  through which a user might interact with the system. For example, devices that can be attached to the computing device  500  might include microphone devices, speaker or stereo systems, video systems or other display devices, keyboard or keypad devices, or other I/O devices for use with specific applications such as card readers or other devices. 
     As mentioned above, I/O controller  540  can interact with audio subsystem  520  and/or display subsystem  530 . For example, input through a microphone or other audio device can provide input or commands for one or more applications or functions of the computing device  500 . Additionally, audio output can be provided instead of, or in addition to display output. In another example, if display subsystem  530  includes a touch screen, the display device also acts as an input device, which can be at least partially managed by I/O controller  540 . There can also be additional buttons or switches on the computing device  500  to provide I/O functions managed by I/O controller  540 . 
     In one embodiment, I/O controller  540  manages devices such as accelerometers, cameras, light sensors or other environmental sensors, or other hardware that can be included in the computing device  500 . The input can be part of direct user interaction, as well as providing environmental input to the system to influence its operations (such as filtering for noise, adjusting displays for brightness detection, applying a flash for a camera, or other features). 
     In one embodiment, computing device  500  includes power management  550  that manages battery power usage, charging of the battery, and features related to power saving operation. Memory subsystem  560  includes memory devices for storing information in computing device  500 . Memory can include nonvolatile (state does not change if power to the memory device is interrupted) and/or volatile (state is indeterminate if power to the memory device is interrupted) memory devices. Memory subsystem  560  can store application data, user data, music, photos, documents, or other data, as well as system data (whether long-term or temporary) related to the execution of the applications and functions of the computing device  500 . 
     Elements of embodiments are also provided as a machine-readable medium (e.g., memory  560 ) for storing the computer-executable instructions. The machine-readable medium (e.g., memory  560 ) may include, but is not limited to, flash memory, optical disks, CD-ROMs, DVD ROMs, RAMs, EPROMs, EEPROMs, magnetic or optical cards, phase change memory (PCM), or other types of machine-readable media suitable for storing electronic or computer-executable instructions. For example, embodiments of the disclosure may be downloaded as a computer program (e.g., BIOS) which may be transferred from a remote computer (e.g., a server) to a requesting computer (e.g., a client) by way of data signals via a communication link (e.g., a modem or network connection). 
     Connectivity via network interface  570  includes hardware devices (e.g., wireless and/or wired connectors and communication hardware) and software components (e.g., drivers, protocol stacks) to enable the computing device  500  to communicate with external devices. The computing device  500  could be separate devices, such as other computing devices, wireless access points or base stations, as well as peripherals such as headsets, printers, or other devices. 
     Network interface  570  can include multiple different types of connectivity. To generalize, the computing device  500  is illustrated with cellular connectivity  572  and wireless connectivity  574 . Cellular connectivity  572  refers generally to cellular network connectivity provided by wireless carriers, such as provided via GSM (global system for mobile communications) or variations or derivatives, CDMA (code division multiple access) or variations or derivatives, TDM (time division multiplexing) or variations or derivatives, or other cellular service standards. Wireless connectivity (or wireless interface)  574  refers to wireless connectivity that is not cellular, and can include personal area networks (such as Bluetooth, Near Field, etc.), local area networks (such as Wi-Fi), and/or wide area networks (such as WiMax), or other wireless communication. 
     Peripheral connections  580  include hardware interfaces and connectors, as well as software components (e.g., drivers, protocol stacks) to make peripheral connections. It will be understood that the computing device  500  could both be a peripheral device (“to”  582 ) to other computing devices, as well as have peripheral devices (“from”  584 ) connected to it. The computing device  500  commonly has a “docking” connector to connect to other computing devices for purposes such as managing (e.g., downloading and/or uploading, changing, synchronizing) content on computing device  500 . Additionally, a docking connector can allow computing device  500  to connect to certain peripherals that allow the computing device  500  to control content output, for example, to audiovisual or other systems. 
     In addition to a proprietary docking connector or other proprietary connection hardware, the computing device  500  can make peripheral connections  580  via common or standards-based connectors. Common types can include a Universal Serial Bus (USB) connector (which can include any of a number of different hardware interfaces), DisplayPort including MiniDisplayPort (MDP), High Definition Multimedia Interface (HDMI), Firewire, or other types. 
     Furthermore, the particular features, structures, functions, or characteristics may be combined in any suitable manner in one or more embodiments. For example, a first embodiment may be combined with a second embodiment anywhere the particular features, structures, functions, or characteristics associated with the two embodiments are not mutually exclusive. 
     While the disclosure has been described in conjunction with specific embodiments thereof, many alternatives, modifications and variations of such embodiments will be apparent to those of ordinary skill in the art in light of the foregoing description. The embodiments of the disclosure are intended to embrace all such alternatives, modifications, and variations as to fall within the broad scope of the appended claims. 
     In addition, well known power/ground connections to integrated circuit (IC) chips and other components may or may not be shown within the presented figures, for simplicity of illustration and discussion, and so as not to obscure the disclosure. Further, arrangements may be shown in block diagram form in order to avoid obscuring the disclosure, and also in view of the fact that specifics with respect to implementation of such block diagram arrangements are highly dependent upon the platform within which the present disclosure is to be implemented (i.e., such specifics should be well within purview of one skilled in the art). Where specific details (e.g., circuits) are set forth in order to describe example embodiments of the disclosure, it should be apparent to one skilled in the art that the disclosure can be practiced without, or with variation of, these specific details. The description is thus to be regarded as illustrative instead of limiting. 
     The following examples pertain to further embodiments. Specifics in the examples may be used anywhere in one or more embodiments. All optional features of the apparatus described herein may also be implemented with respect to a method or process. 
     Example 1 is an apparatus comprising a bonding nozzle comprising one or more channels in a bonding surface, the one or more channels comprising a first channel portion in an inner region of the bonding surface and a second channel portion along an outer periphery of the bonding surface, the one or more channels in fluid communication with a vacuum port; and a vacuum relief conduit within the bonding nozzle, the vacuum relief conduit comprising a first opening into the second channel portion along the outer periphery of the bonding surface and a second opening along an exterior wall of the bonding nozzle. 
     Example 2 includes all of the features of example 1, wherein the bonding nozzle has a rectangular periphery, wherein one or more channels of the second channel portion extend along orthogonal edges of the rectangular periphery, and wherein the one or more channels of the second channel portion has a first end and a second end. 
     Example 3 includes all the features of examples 1 or 2, wherein a first channel of the second channel portion is joined to a second channel of the second channel portion, wherein the first channel is orthogonal to the second channel. 
     Example 4 includes all of the features of example 3, wherein the vacuum relief conduit is a first vacuum relief conduit and opens into the first channel near the first end, and 
     wherein a second conduit opens into the first channel near the second end. 
     Example 5 includes all of the features of example 4, wherein a third vacuum relief conduit opens into the first channel between the first and second vacuum relief conduits. 
     Example 6 includes all of the features of any one of examples 1 through 5, wherein a first portion of the vacuum relief conduit is orthogonal to the bonding surface and extends partially within the bonding nozzle, and wherein a second portion of the vacuum relief conduit is substantially parallel to the bonding surface and extends to the exterior wall of the bonding nozzle. 
     Example 7 includes all of the features of example 6, wherein the second portion opens to an ambient atmosphere that surrounds the bonding nozzle. 
     Example 8 includes all of the features of any one of examples 1 through 7, wherein a central conduit extends from a central region of the bonding surface through the bonding nozzle, wherein a first end of the central conduit is fluidically coupled to the first channel portion and a second end of the central conduit is coupled to the vacuum port on the bonding nozzle. 
     Example 9 includes all of the features of example 8, wherein the first channel portion comprises one or more interior channels extending between the central conduit and the second channel portion, wherein the one or more interior channels is in fluidic communication with the second channel portion. 
     Example 10 includes all of the features of example 9, wherein the one or more interior channels extend between the central conduit and the intersection of a first peripheral channel of the second channel portion and a second peripheral channel of the second channel portion, wherein the first peripheral channel is orthogonal to the second peripheral channel. 
     Example 11 is a system comprising a thermal compression bonder, the thermal compression bonder comprising a bonding nozzle comprising one or more channels in a bonding surface, the one or more channels comprising a first channel portion in an inner region of the bonding surface in fluidic communication with a second channel portion along an outer periphery of the bonding surface, the one or more channels in fluid communication with a vacuum port; and a vacuum relief conduit within the bonding nozzle, the vacuum relief conduit comprising a first opening into the second channel portion along the outer periphery of the bonding surface and a second opening along an exterior wall of the bonding nozzle. 
     Example 12 includes all of the features of example 11, wherein the first channel portion is fluidically coupled to the second channel portion and to a central conduit extending between a vacuum port and a central region of the bonding surface, wherein the central conduit is coupled to a vacuum source to create a vacuum within the first and second channel portions when the bonding surface is interfaced to a substrate. 
     Example 13 includes all of the features of example 12, wherein the first channel portion is fluidically coupled to the second channel portion and to a central conduit extending between a vacuum port and a central region of the bonding surface, wherein the central conduit is coupled to a vacuum source to create a vacuum within the first and second channel portions when the bonding surface is interfaced to a substrate. 
     Example 14 is a method for using a thermal compression bonder, the method comprising interfacing a bonding surface of a bonding nozzle to an integrated circuit (IC) die to be bonded to a substrate, the bonding surface comprising one or more channels, the one or more channels comprising a first channel portion within a central portion of the bonding surface fluidically coupled to a second channel portion along a periphery of the bonding surface; and forming a vacuum gradient within the one or more channels, wherein the vacuum gradient is minimal at the periphery of the bonding surface and maximal within the central portion of the bonding surface. 
     Example 15 includes all of the features of example 14, wherein interfacing the bonding surface of the bonding nozzle to the IC die comprises aligning the second channel portion with the edges of the IC die. 
     Example 16 includes all of the features of example 15, wherein forming a vacuum gradient within the one or more channels comprises coupling a vacuum source to the one or more channels, wherein an ambient atmosphere flows into the one or more channels through at least one vacuum relief conduit in fluidic communication with the second channel portion. 
     Example 17 includes all of the features of example 16, wherein forming a vacuum gradient within the one or more channels comprises providing metered suction of the ambient atmosphere through the at least one vacuum relief conduit such that the second channel portion has a smaller vacuum than the first channel portion. 
     Example 18 includes all of the features of example 17, wherein forming a vacuum gradient within the one or more channels comprises forming a vacuum gradient within the first channel portion that is decreases from the central region of the bonding surface toward the periphery of the bonding surface. 
     Example 19 includes all of the features of example 18, wherein interfacing the bonding surface of the bonding nozzle to the IC die comprises forming a clamping force gradient between the bonding surface and the IC die such that the clamping force is maximal within a central region of the IC die and minimal within a peripheral region of the IC die, and wherein the clamping force gradient is proportional to the vacuum gradient. 
     Example 20 includes all of the features of example 19, wherein forming the clamping force gradient comprises forming a symmetrical vacuum gradient between the central region of the IC die and the peripheral region of the IC die, wherein the clamping force is greatest within the central portion of the IC die and diminishes substantially equally in all directions from the central portion toward opposing edges of the IC die. 
     An abstract is submitted with the understanding that it will not be used to limit the scope or meaning of the claims. The following claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate embodiment.