WO2017146739A1

WO2017146739A1 - Pressure and load measurement for silicon die thermal solution attachment

Info

Publication number: WO2017146739A1
Application number: PCT/US2016/019964
Authority: WO
Inventors: Naga Sivakumar YAGNAMURTHY; Betsegaw GEBREHIWOT; Tannaz HARIRCHIAN; Joseph B. PETRINI; Shankar Devasenathipathy; Seth B. REYNOLDS; Pramod Malatkar
Original assignee: Intel Corp
Current assignee: Intel Corp
Priority date: 2016-02-26
Filing date: 2016-02-26
Publication date: 2017-08-31
Anticipated expiration: 2018-08-26

Abstract

Embodiments are generally directed to pressure and load measurement for silicon die thermal solution attachment. An embodiment of a calibration machine includes: a base; a first post and a second post, a first end of each of the posts being coupled with the base; a set of fixtures, a first fixture being coupled with the first post and second post and a second fixture being moveable coupled with the first post and the second post; an actuator, the actuator being coupled with the first fixture and being operable to provide force on the second fixture; a load cell coupled with the base; and one or more calibration stages on the load cell and below the set of fixtures.

Description

PRESSURE AND LOAD MEASUREMENT FOR SILICON DIE

THERMAL SOLUTION ATTACHMENT

TECHNICAL FIELD

[0001] Embodiments described herein generally relate to the field of electronic devices and, more particularly, to pressure and load measurement for silicon die thermal solution attachment.

BACKGROUND

[0002] Semiconductor packages undergo mechanical loading at various stages of the manufacturing, assembly, and test process. In particular, during the assembly of the thermal solution in a system environment, mechanical loads are applied to ensure contact of the thermal solution to silicon die. These loads can be static, dynamic, or both in nature, and may be applied over a short or long periods of time.

[0003] It is important to characterize the applied loads and the resulting contact pressure on the silicon to evaluate die crack risk. However, the measurement of the contact pressure at the interface for a die is complex and requires special techniques without altering the mechanical boundary conditions or the state of stress.

[0004] Conventional methods used to measure the in-situ load and pressure distribution are pressure-sensitive paper, piezoresistive based pressure sensors, and load cells. However, there are challenges associated with these measurement techniques, including accuracy, repeatability, and reproducibility of the measurements.

[0005] Embodiments described here are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings in which like reference numerals refer to similar elements. DESCRIPTION OF DRAWINGS

[0006] Figure 1 illustrates calibration and measurement elements according to an embodiment;

[0007] Figure 2 is an illustration of a high level process for pressure and load measurement for silicon die thermal solution attachment according to an embodiment;

[0008] Figure 3A is an illustration of a calibration machine according to an embodiment;

[0009] Figure 3B is an illustration of a calibration machine according to an embodiment; [0010] Figure 4A is an illustration of a pressure bladder for conditioning and equilibration of a piezoresistive pressure sensor according to an embodiment;

[0011] Figure 4B is an illustration of a pressure bladder with automatic pressure control for conditioning and equilibration of a piezoresistive pressure sensor according to an embodiment;

[0012] Figure 5 illustrates a process for measurement of pressure and load distribution according to an embodiment;

[0013] Figure 6 illustrates a process for preparation of a piezoresistive pressure sensor according to an embodiment;

[0014] Figure 7 illustrates a process for conditioning of a piezoresistive pressure sensor according to an embodiment;

[0015] Figure 8 illustrates a process for equilibration of a piezoresistive pressure sensor according to an embodiment;

[0016] Figure 9 illustrates a process for calibration of a piezoresistive pressure sensor according to an embodiment;

[0017] Figure 10 illustrates a process for measurement of load and pressure distribution on a silicon die utilizing a piezoresistive pressure sensor according to an

embodiment;

[0018] Figure 11A illustrates a user interface for tailored logic in software to operate the calibration and measurement system according to an embodiment;

[0019] Figure 11B illustrates a user interface for tailored logic in software to provide for automatic pressure control in conditioning and equilibration of a piezoresistive pressure sensor according to an embodiment;

[0020] Figure 12 illustrates calibration logic according to an embodiment; and

[0021] Figure 13 illustrates a process for calibration operation utilizing calibration logic according to an embodiment.

DETAILED DESCRIPTION

[0022] Embodiments described herein are generally directed to pressure and load measurement for silicon die thermal solution attachment.

[0023] For the purposes of this description:

[0024] "Thermal solution" refers in general to one or more elements for the cooling of an electronic component or package, including a heat spreader, heat sink, or similar element. [0025] In some embodiments, an apparatus, system, or method provides for accurate and consistent measurement of pressure and load on silicon dies during thermal solution attachment. In the enabling of a thermal solution on a die, including a silicon die, a significant amount of pressure may be applied to the die in order to properly attach the thermal solution. In certain circumstances, the pressure will lead to damage or failure of the die. For this reason, it is important to provide for measurement of the pressure and load applied to a silicon during the thermal solution enablement process. Specifically, when a thermal heat sink is attached on a semiconductor package, knowledge of the total load applied and the pressure distribution on the die, either statically, dynamically, or both is needed to ensure that damaging loads are not presented during the heat sink application.

[0026] In particular, the attachment of a heat sink to a silicon die will require the application of torque to screws to attach the heat sink, resulting in the application of pressure to certain locations on the silicon die. Moreover, the pressure and load may vary considerably depending on time and location during the enablement process.

[0027] However, conventional processes for measurement of the pressure and load connected with thermal solution enablement are generally inaccurate and provide results that are not repeatable. Accurate measurement of the total load and pressure distribution in testing is difficult because of the lack of consistent tools and processes that allow for consistent and controlled measurement of pressure on a die.

[0028] In some embodiments, an apparatus, system, and process provide for accurate and repeatable measurements utilizing piezoresistive pressure sensors for pressure and load on silicon dies during enablement of a thermal solution. In some embodiments, the piezoresistive pressure sensor is placed between a silicon die and a heat sink in a metrology to quantify data regarding total load and pressure distribution on the package, and thus assess die crack risk in the thermal solution enablement process.

[0029] While piezoresistive pressure sensors are commercially available, there are significant challenges to achieving accurate and repeatable measurements. As a result, such sensors are commonly used for qualitative data, but not quantitative data. However, there is a need for quantitative measurements in measurement of pressure and load on dies during thermal solution enablement. Existing methods to calibrate commercially available piezoresistive pressure sensors are rudimentary and don't take into consideration all the challenges associated with these type of sensors, such as sensor creep, hysteresis, and other issues.

[0030] Piezoresistive pressure sensors are generally constructed of polymer materials with embedded conductive particles. When pressure is applied, resistance of the sensor changes. However the challenges associated with these type of polymer based sensors include time dependence, sensor creep, and hysteresis. The viscoelastic behavior of the sensor generally requires a certain wait time in between measurements, which can result in inaccuracy if this behavior isn't properly and consistently addressed.

[0031] In some embodiments, a process improves the accuracy of measurements utilizing piezoresistive pressure sensors and reduces the incidence of time dependence, sensor creep, and hysteresis issues. In some embodiments, a calibration process provides for accurate, repeatable, and reproducible results within, for example, a 10% error. In a particular example, a piezoresistive pressure sensor is a Tekscan Sensor Model 4205 of Tekscan Inc.

[0032] As referred to herein, the sensel area of piezoresistive pressure sensor is the area of the sensor where the sensels of the sensor are located. Further, a piezoresistive pressure sensor may utilize a handle to transfer data from the sensor to software. In a particular example, a VersaTek Handle is the handle containing data acquisition electronics used to transfer data from the Tekscan sensor to the I-Scan® software of Tekscan, Inc.

[0033] Figure 1 illustrates calibration and measurement elements according to an embodiment. In some embodiments, an apparatus, system, and process for pressure and load measurement for silicon die thermal solution attachment includes one or more of:

[0034] (1) Calibration machine 120: In some embodiments, a calibration machine (CM) is operable to provide for performance of in-situ calibration of piezoresistive pressure sensors and further to aid in validation of the sensors. A calibration machine may include the machine illustrated in Figures 3A and 3B. In some embodiments, an apparatus or system includes, but is not limited to, the following:

[0035] (a) A load cell to measure force applied on a piezoresistive sensor.

[0036] (b) One or more actuators to provide pressure for calibration. In some embodiments, the load cell is used to control speed of the one or more actuators.

[0037] In some embodiments, an apparatus or system may also include:

[0038] (c) A ball head to eliminate tilt during calibration to achieve uniform loading. In some embodiments, the ball head is coupled to one or more fixtures of the calibration machine.

[0039] (d) A vacuum suction assembly to hold a thermal solution in place to assist in validating the measurements. In some embodiments, the vacuum suction assembly includes a plurality of suction cups to mount and securely hold a thermal solution mounting unit on the calibration machine. [0040] (2) Calibration and measurement processing 140: In some embodiments, a system includes tailored logic in software to operate the calibration and measurement system. In some embodiments, the logic is operable to automate processes for pressure measurements. In some embodiments, the logic is implemented in the LabVIEW™ development environment of National Instruments.

[0041] (3) Calibration and measurement procedure 160 - In some embodiments, a process includes a detailed procedure for collecting quantitative measurements using piezoresistive pressure sensors to enable accurate and repeatable results.

[0042] Figure 2 is an illustration of a high level process for pressure and load measurement for silicon die thermal solution attachment according to an embodiment. In some embodiments, a process may include, but is not limited to, the following:

[0043] (1) Preconditioning and equilibration of piezoresistive pressure sensor 210 - In some embodiments, a process provides for conditioning of the piezoresistive pressure sensor, which includes a specified process of pressure application and release, including required waiting times between process elements. In some embodiments, the process further includes equilibration of the piezoresistive pressure sensor utilizing the specific application of pressure levels on the sensor. Equilibration refers to a process for normalizing a sensor and system such that the output of every sensing element (or sensel) of a sensor is the same when a uniform pressure is applied to the sensor. Software or other logic may operate to determine scale factors for the sensing elements to compensate for any variation in the outputs of the sensing elements.

[0044] (2) Calibration of piezoresistive pressure sensor 220 - In some embodiments, a process provides for conditioning of the equilibrated piezoresistive pressure sensor, including processes to be performed at specified data points.

[0045] (3) Measurement of load and pressure distribution using piezoresistive pressure sensor 230 - In some embodiments, a process provides for measuring load and pressure on a silicon during the processes for the application of a thermal solution, including the driving of screws that would be utilizes in the attachment of such thermal solution.

[0046] Figure 3A is an illustration of a calibration machine according to an embodiment. In some embodiments, a calibration machine 300, which is shown in detail in Figure 3B, is provided for performance of in-situ calibration of piezoresistive pressure sensors. In some embodiments, the calibration machine 300 includes:

[0047] (a) A load cell 305 to convert mechanical force into an electrical output signal. In a particular example, the load cell may be a load cell of Interface, Inc. In some embodiments, the load cell reading is used by the LabVIEW program or other control element to control speed of the actuator.

[0048] (b) One or more actuators 310 to provide pressure and thus apply load to a piezoresistive pressure sensor.

[0049] (c) Metal posts or columns 355 for support of components of the calibration machine.

[0050] (d) Metal fixtures 350 to mount and support the actuator firmly from the top, wherein the fixtures may include a top fixture that is coupled in place on the metal posts 355 and a bottom fixture that is movably coupled with the posts 355 to allow for application of force by the actuator. In some embodiments, the calibration machine may include a ball head or similar component to eliminate tilt during calibration to achieve uniform loading.

[0051] (e) Ball bearing bushings 340 to allow for smooth sliding of the bottom fixture on the posts

[0052] (f) One or more calibration stages, such as translational and rotational calibration stages 345 for correcting alignment in calibration operation.

[0053] (g) Base 360 for the calibration machine, wherein the posts 355 are coupled with the base 360. The fixtures 350, posts 355, and base 360 are the main components of the frame of the CL machine.

[0054] In some embodiments, components utilized with the calibration machine 300 for calibration operation may include, but are not limited to, the following:

[0055] (a) First support block 315, such as a block composed of aluminum or other stiff metal, to support piezoresistive pressure sensors.

[0056] (b) Second support block 320, such as a block composed of copper or other material, to support the first support block on the calibration machine.

[0057] (c) Calibration block 325 for calibration of piezoresistive pressure sensors. In an example, the calibration block may be coupled with silicon dies to the first support block 315.

[0058] (e) Thermal solution mounting unit 330, an assembly including modified backing plate mounting block, the modified backing plate, and the thermal solution (TS). In some embodiments, the thermal solution is to be coupled with the modified backing plate by a certain number of screws. In some embodiments, the modified backing plate is coupled with the modified backing plate mounting block by a certain number of screws, wherein there may be multiple different types of modified backing plates that may be coupled with the modified backing plate. [0059] In some embodiments, the thermal solution mounting unit 330 includes a vacuum suction assembly to hold a thermal solution in place to assist in validating the measurements. In some embodiments, the vacuum suction assembly includes a plurality of suction cups to mount and securely hold the thermal solution mounting unit on the calibration machine.

[0060] In some embodiments, the calibration machine 300 includes at least one communication interface to receive actuator control signals from a control element to control the actuator 310. In some embodiments, the calibration machine 300 provides data via the at least one communication interface, wherein the data may include actuator position values and load cell values.

[0061] Figure 3B is an illustration of a calibration machine according to an embodiment. As illustrated, the calibration machine 300 is an exploded view of the calibration machine shown in Figure 3 A, Figure 3B includes illustration of the load cell 305, actuator 310, translation and rotational calibration stages 345, fixtures 350, posts 355, and base 360.

[0062] Figure 4A is an illustration of a pressure bladder for conditioning and equilibration of a piezoresistive pressure sensor according to an embodiment. As illustrated, the pressure bladder 400 allows for insertion of a piezoresistive pressure sensor and the application of pressure on the sensor. The pressure bladder may include a unit of Tekscan Inc.

[0063] A pressure bladder 400 such as illustrated in Figure 4A may be utilized in the conditioning of a piezoresistive pressure sensor, such as provided in Figure 7, and the equilibration of a piezoresistive pressure sensor, such as illustrated in Figure 8. In some embodiments, the pressure bladder 400 may be utilized to apply uniform pressure on the sensel area of a piezoresistive pressure sensor that is inserted into the pressure bladder. A pressure regulator is generally utilized to control how much pressure is applied by the pressure bladder.

[0064] Figure 4B is an illustration of a pressure bladder with automatic pressure control for conditioning and equilibration of a piezoresistive pressure sensor according to an embodiment. In some embodiments, the pressure bladder 400 further includes a connection for an electric pressure regulator 410. In some embodiments, the operation of the pressure bladder via the automatic pressure regulator is controlled by signals from a control element, which may include use of a data acquisition module, such as data acquisition module 1220 illustrated in Figure 12.

[0065] Figure 5 illustrates a process for measurement of pressure and load distribution according to an embodiment. In some embodiments, a process for measurement of pressure and load distribution includes, but is not limited to, the following: [0066] (a) Preparation of the piezoresistive pressure sensor for measurement 505, as further illustrated in Figure 6.

[0067] (b) Conditioning of the piezoresistive pressure sensor for measurement 510, as further illustrated in Figure 7.

[0068] (c) Equilibration of the piezoresistive pressure sensor 515, as further illustrated in Figure 8.

[0069] (d) Calibration of the piezoresistive pressure sensor for measurement 520 and verification of the calibration 525, as further illustrated in Figure 9.

[0070] (e) Measurement of the load and pressure distribution for a device under test utilizing the piezoresistive pressure sensor for measurement, as further illustrated in Figure 10.

[0071] Figure 6 illustrates a process for preparation of a piezoresistive pressure sensor according to an embodiment. In some embodiments, a process for preparation of a piezoresistive pressure sensor includes, but is not limited to, the following:

[0072] (a) Selection of a piezoresistive pressure sensor 605, wherein the sensor may include a Tekscan Sensor Model 4205 or other sensor constructed of polymer materials with embedded conductive particles.

[0073] (b) Inspection of the piezoresistive pressure sensor 610 to ensure the sensor is not damaged and is suitable for a measurement for a particular device under test.

[0074] (c) Preparation of the piezoresistive pressure sensor 615, which may include trimming the sensor to cut off portions as required to place the sensel area of the piezoresistive pressure sensor on the device under test.

[0075] (d) Handle selection for the piezoresistive pressure sensor 620.

[0076] (e) Thermal interface material (TIM) selection for the device under test 625. In some embodiments, a particular TIM is required, wherein the TIM may include PCM (phase change material) TIM. In a particular example, the PCM TIM has a thickness of 0.20 mm (millimeters).

[0077] Figure 7 illustrates a process for conditioning of a piezoresistive pressure sensor according to an embodiment. In some embodiments, a process for conditioning of a piezoresistive pressure sensor may include, but is not limited to, the following:

[0078] (a) Selection of the sensor for measurement 705, which may be prepared as illustrated in Figure 6.

[0079] (b) Insertion of the piezoresistive pressure sensor into a pressure bladder 710, such as the pressure bladder illustrated in Figure 4A or 4B. [0080] (c) Application of pressure on the piezoresistive pressure sensor utilizing the pressure bladder 720, wherein the pressure is a certain pressure level, such as 100 psi (pounds per square inch). In some embodiments, the application and release of pressure is controlled automatically by a control unit, wherein automatic control may include control operation by a data acquisition module 1220 as illustrated in Figure 12.

[0081] (d) Waiting a certain time period, such as 5 seconds, while the piezoresistive pressure sensor is under pressure 725.

[0082] (e) Releasing the pressure of the pressure bladder from the piezoresistive pressure sensor 730.

[0083] (f) Removing the piezoresistive pressure sensor from the pressure bladder

735.

[0084] (g) If there are additional repetitions of the process for application of pressure, the processes 710-735 are repeated. In some embodiments, the processes are repeated a certain number of times, such as three repetitions. However, embodiments are not limited to a particular number of repetitions .

[0085] (h) Upon the completion of the required number of iterations of the processes for application of pressure on the piezoresistive pressure sensor 740, a process may proceed with waiting a certain period of time 745, such as at least 5 minutes and no more than 15 minutes, before proceeding to a following process.

[0086] (i) Proceeding to equilibration of the piezoresistive pressure sensor 750, which may include the processes illustrated in Figure 8.

[0087] Figure 8 illustrates a process for equilibration of a piezoresistive pressure sensor according to an embodiment. In some embodiments, a process for equilibration of a piezoresistive pressure sensor may include, but is not limited to, the following:

[0088] (a) Receiving a conditioned sensor 805, which may be conditioned as illustrated in Figure 7.

[0089] (b) Insertion of the piezoresistive pressure sensor into a pressure bladder 810, such as the pressure bladder illustrated in Figure 4A or 4B.

[0090] (c) Setting a pressure level of the pressure bladder to a first pressure value 815, wherein the pressure is a certain pressure level, such as 20 psi. In some embodiments, the application and release of pressure is controlled automatically by a control unit, wherein automatic control may include control operation by a data acquisition module 1220 as illustrated in Figure 12. [0091] (d) Equilibrating the piezoresistive pressure sensor as the set pressure value 820. In some embodiments, equilibration includes equilibration by I-Scan software for a certain period, such as 60 seconds.

[0092] (e) If there are any additional pressure levels for the equilibration of the piezoresistive pressure sensor 825, then the pressure of the pressure bladder is increased to the next pressure level 830, and process returns to equilibrating the piezoresistive pressure sensor as the next set pressure value 820. For example, equilibration may include a second equilibration point at 50 psi and a third equilibration point at 99 psi.

[0093] (f) If there are no additional pressure levels for the equilibration of the piezoresistive pressure sensor 825, then the equilibration is applied to the piezoresistive pressure sensor 835.

[0094] (g) Releasing the pressure of the pressure bladder from the piezoresistive pressure sensor and removing the piezoresistive pressure sensor from the pressure bladder 840.

[0095] (h) Upon the completion of the equilibration, a process may proceed with waiting a certain period of time 845, such as at least 5 minutes and no more than 20 minutes.

[0096] (i) Proceeding to calibration of the piezoresistive pressure sensor 850, which may include the processes illustrated in Figure 9.

[0097] Figure 9 illustrates a process for calibration of a piezoresistive pressure sensor according to an embodiment. In some embodiments, a process for calibration of a piezoresistive pressure sensor 900 utilizes a calibration machine (CM) as illustrated in Figures 3A and 3B.

[0098] In some embodiments, a process for calibration includes, but is not limited to, the following:

[0099] (a) Receiving an equilibrated piezoresistive pressure sensor 902, such as a piezoresistive pressure sensor that has been processed as illustrated in Figure 8,

[00100] (b) Placing a calibration block on the CM 905.

[00101] (c) Attaching the piezoresistive pressure sensor to a first support block, such as an aluminum support block 910 or support block composes of another stiff metal. The first support block may include the first support block 315 illustrated in Figure 3 A.

[00102] (d) Placing a second support block, such as a copper support block, on the CM

915. The second support block may include the second support block 320 illustrated in Figure 3A.

[00103] (e) Placing the first support block on the second support block with the sensel area of the piezoresistive pressure sensor being on the silicon dies 920. [00104] (f) Applying a TIM, such as a PCM (phase change material) TIM, on a thermal solution 925.

[00105] (g) Mounting a thermal solution mounting unit on the CM 930, where unit may include TS mounting unit 330 illustrated in Figure 3A.

[00106] (h) Performing the calibration processes for the piezoresistive pressure sensor at certain data points 935. In some embodiments, calibration is to be performed during loading of the sensor (i.e., when the pressure applied to the sensor by the actuator is increased) to provide for better accuracy.

[00107] (i) Release the thermal solution mounting unit 940.

[00108] (j) If needed, verify the calibration by repeating the calibration processes 945.

[00109] (k) Upon the completion of the calibration and verification of calibration, a process may proceed with waiting a certain period of time 950, such as at least 5 minutes and no more than 15 minutes.

[00110] (1) Proceeding to measurement of load and pressure distribution 955, which may include the processes illustrated in Figure 10.

[00111] Figure 10 illustrates a process for measurement of load and pressure distribution on a silicon die utilizing a piezoresistive pressure sensor according to an

embodiment.

[00112] In some embodiments, a process for measurement of load and pressure distribution on a silicon die, the silicon die being a particular device under test (DUT) to which a thermal solution is to be attached, includes, but is not limited to, the following:

[00113] (a) Receiving an equilibrated piezoresistive pressure sensor 1002, such as a piezoresistive pressure sensor that has been processed as illustrated in Figure 9.

[00114] (b) Placing sensel area of the piezoresistive pressure sensor on the DUT 1005.

[00115] (c) Placing a PCM TIM on the thermal solution 1010.

[00116] (d) Place thermal solution on the sensel area 1015 for attachment to the DUT.

[00117] (e) Commence recording of sensor readings 1020, such sensor readings providing data regarding the load and pressure distribution on the DUT during the attachment of the thermal solution.

[00118] (f) Tighten screws in the set order for the attachment of the thermal solution

1025, thereby providing the force that will be required in the manufacture of the device.

[00119] (g) Upon completion of the attachment of the thermal solution, stop the recording process and save the recording of the data reflecting the load and pressure distribution on the DUT 1030. In some embodiments, the recorded data represents quantitative data that may be utilized in evaluating the amount of force applied to the DUT in the process of attaching the thermal solution.

[00120] (h) Unscrew the screws holding the thermal solution in place, and remove the thermal solution from the sensel area of the piezoresistive pressure sensor 1035.

[00121] (i) Wait a particular time period before addressing other measurements 1040, such as at least 5 minutes but no more than 20 minutes.

[00122] (j) Take additional measurements as required, with the sensor to be reconditioned if a longer wait period (greater than 20 minutes, for example) occurs 1045.

[00123] Figure 11A illustrates a user interface for tailored logic in software to operate the calibration and measurement system. In some embodiments, the logic 1100 is implemented in in the LabVIEW development environment. In some embodiments, the logic includes load information; position information; actuator control, including target load and actuator speed; and provision of timers for processes.

[00124] Figure 11B illustrates a user interface for tailored logic in software to provide for automatic pressure control in conditioning and equilibration of a piezoresistive pressure sensor according to an embodiment. In some embodiments, a user interface 1150 allows for automatic control of conditioning and equilibration of a piezoresistive pressure sensor, which may include providing automatic control of a pressure bladder 400 utilizing an electric pressure regulator 410, such as illustrated in Figure 4B.

[00125] Figure 12 illustrates calibration logic according to an embodiment. In some embodiments, an apparatus, system, and process to support calibration of sensor, such as provided in Figure 9, includes one or more of:

[00126] (a) Communication Module 1210: Module to support communications with the actuator and with the load cell of a calibration machine.

[00127] (b) Data Acquisition Module 1220: Module to provide for acquisition of data, including reading the force applied, the actuator position, and other data for a calibration operation with a calibration machine. In some embodiments, the acquisition operation further includes providing automatic control of pressure for conditioning and equilibration of a piezoresistive pressure sensor, such as automatic control of a pressure bladder 400 as illustrated in Figure 4B via an electric pressure regulator 410.

[00128] (c) Actuator Control Module 1230: Module to control operation of the actuator, such as controls to provide push, pull, and stop actuator operations. [00129] (d) Actuator Limit Module 1240: Module to specify limits (or thresholds) in force and actuator position, wherein the actuator is stopped if the force or actuator position falls outside of the limits.

[00130] (e) Calibration Automation Module 1250: Module to automate calibration operation, with the actuator to drive until the actuator reaches specified load values.

[00131] (f) Time Module 1260: Module to provide timing/stopwatch operation for calibration processing.

[00132] Figure 13 illustrates a process for calibration operation utilizing calibration logic according to an embodiment. In some embodiments, a process for calibration utilizes the calibration logic illustrated in Figure 12.

[00133] In some embodiments, a process for calibration 1300 includes, but is not limited to, the following:

[00134] (a) Starting calibration program for a calibration operation 1305.

[00135] (b) Establishing communications with the actuator and load cell of a calibration machine utilizing a communication module 1310, where the communication module may be the communication module 1210 illustrated in Figure 12.

[00136] (c) Receiving current load cell force and actuator position data from the calibration machine 1312;

[00137] (d) Reading a load cell force limit and an actuator position limit 1315, where the limit data may be acquired through use of the data acquisition module 1220 illustrated in Figure 12.

[00138] (e) Display load cell and actuator position values 1320.

[00139] (f) Direct movement of the actuator in the calibration operation 1325, wherein control of movement of the actuator is performed utilizing the actuator control module 1230 illustrated in Figure 12.

[00140] (g) Determine if the load cell value is outside the load cell force limit or the actuator position value is outside of the actuator position limit 1330.

[00141] (h) If either the load cell force or actuator position values are outside limits, then halting the movement of the actuator 1335.

[00142] (i) If load cell force and actuator position values are within limits, then move the actuator as specified for the calibration operation 1340, and determine whether the additional movement results in reaching the load cell or actuator position limits 1345, and, if so, halt the movement of the actuator 1335. [00143] (j) Following the halting of actuator movement, if the process requires moving the actuator again 1350, the process continues with moving the actuator as specified 1340. If not, the calibration program is stopped 1355.

[00144] In some embodiments, the process for calibration further includes displaying one or more timer values for the calibration operation, where the one or more timer values includes timing for any minimum or maximum wait periods.

[00145] In the description above, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the described embodiments. It will be apparent, however, to one skilled in the art that embodiments may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form. There may be intermediate structure between illustrated components. The components described or illustrated herein may have additional inputs or outputs that are not illustrated or described.

[00146] Various embodiments may include various processes. These processes may be performed by hardware components or may be embodied in computer program or machine- executable instructions, which may be used to cause a general-purpose or special-purpose processor or logic circuits programmed with the instructions to perform the processes.

Alternatively, the processes may be performed by a combination of hardware and software.

[00147] Portions of various embodiments may be provided as a computer program product, which may include a computer-readable medium having stored thereon computer program instructions, which may be used to program a computer (or other electronic devices) for execution by one or more processors to perform a process according to certain embodiments. The computer-readable medium may include, but is not limited to, magnetic disks, optical disks, read-only memory (ROM), random access memory (RAM), erasable programmable read-only memory (EPROM), electrically-erasable programmable read-only memory (EEPROM), magnetic or optical cards, flash memory, or other type of computer-readable medium suitable for storing electronic instructions. Moreover, embodiments may also be downloaded as a computer program product, wherein the program may be transferred from a remote computer to a requesting computer.

[00148] Many of the methods are described in their most basic form, but processes can be added to or deleted from any of the methods and information can be added or subtracted from any of the described messages without departing from the basic scope of the present

embodiments. It will be apparent to those skilled in the art that many further modifications and adaptations can be made. The particular embodiments are not provided to limit the concept but to illustrate it. The scope of the embodiments is not to be determined by the specific examples provided above but only by the claims below.

[00149] If it is said that an element "A" is coupled to or with element "B," element A may be directly coupled to element B or be indirectly coupled through, for example, element C. When the specification or claims state that a component, feature, structure, process, or characteristic A "causes" a component, feature, structure, process, or characteristic B, it means that "A" is at least a partial cause of "B" but that there may also be at least one other component, feature, structure, process, or characteristic that assists in causing "B." If the specification indicates that a component, feature, structure, process, or characteristic "may", "might", or "could" be included, that particular component, feature, structure, process, or characteristic is not required to be included. If the specification or claim refers to "a" or "an" element, this does not mean there is only one of the described elements.

[00150] An embodiment is an implementation or example. Reference in the specification to "an embodiment," "one embodiment," "some embodiments," or "other embodiments" means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments. The various appearances of "an embodiment," "one embodiment," or "some embodiments" are not necessarily all referring to the same embodiments. It should be appreciated that in the foregoing description of exemplary embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various novel aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed embodiments requires more features than are expressly recited in each claim. Rather, as the following claims reflect, novel aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims are hereby expressly incorporated into this description, with each claim standing on its own as a separate embodiment.

[00151] In some embodiments, a calibration machine includes a base; a first post and a second post, a first end of each of the posts being coupled with the base; a set of fixtures, a first fixture being coupled with the first post and second post and a second fixture being moveable coupled with the first post and the second post; an actuator, the actuator being coupled with the first fixture and being operable to provide force on the second fixture; a load cell coupled with the base; and one or more calibration stages on the load cell and below the set of fixtures. [00152] In some embodiments, the calibration machine further includes at least one communication interface for communication with a control element.

[00153] In some embodiments, the actuator is to operate in response to received control commands.

[00154] In some embodiments, the actuator is to provide position information via the at least one communication interface.

[00155] In some embodiments, the load cell is to provide load data via the at least one communication interface.

[00156] In some embodiments, the one or more calibration stages include a translational stage to translate a location for calibration and a rotational stage to rotate a position for calibration.

[00157] In some embodiments, the calibration machine further includes a ball head coupled with the one or more fixtures to eliminate tilt during calibration.

[00158] In some embodiments, the calibration machine further includes a vacuum suction assembly to hold a thermal solution for validating the measurements, the vacuum suction assembly including a plurality of suction cups to hold the thermal solution in place on the calibration machine

[00159] In some embodiments, a method includes conditioning and equilibrating a piezoresistive pressure sensor; supporting the piezoresistive pressure sensor with one or more blocks; placing a sensel area of the piezoresistive pressure sensor on one or more silicon dies; mounting a thermal solution on the piezoresistive pressure sensor; applying pressure to the thermal solution mounting unit with an actuator; and acquiring calibration data for the piezoresistive pressure sensor during the application of pressure on the piezoresistive pressure sensor.

[00160] In some embodiments, the method further includes applying a thermal interface material (TIM) on the thermal solution prior to mounting the thermal solution on the piezoresistive pressure sensor.

[00161] In some embodiments, the TIM is a phase change material (PCM).

[00162] In some embodiments, the thermal solution is contained in a mounting unit.

[00163] In some embodiments, acquiring calibration data includes acquiring data during loading of the piezoresistive pressure sensor in which pressure applied to the sensor is increased.

[00164] In some embodiments, the method further includes placing the sensel area of the piezoresistive pressure sensor on a device under test; placing a thermal solution on sensel area and attaching the thermal solution to the device under test; and recording sensor readings from the piezoresistive pressure sensor, the sensor readings being adjusted based on the equilibration data and calibration data for the piezoresistive pressure sensor.

[00165] In some embodiments, the sensor readings provide quantitative data for load and pressure distribution resulting from attachment of the thermal solution.

[00166] In some embodiments, conditioning the piezoresistive pressure sensor includes applying a certain pressure to the piezoresistive pressure sensor and releasing the pressure a plurality of times.

[00167] In some embodiments, equilibrating the piezoresistive pressure sensor includes applying a series of increasing pressure values to the piezoresistive pressure sensor and obtaining equilibration data from the piezoresistive pressure sensor.

[00168] In some embodiments, the pressure is applied to the piezoresistive pressure sensor utilizing a pressure bladder.

[00169] In some embodiments, the conditioning and equilibrating of the piezoresistive pressure sensor includes automatic control of the application and release of pressure on the piezoresistive pressure sensor.

[00170] In some embodiments, supporting the piezoresistive pressure sensor with one or more blocks includes attaching the piezoresistive pressure sensor to a first block and placing the first block on a second block. In some embodiments, the first metal block is composed of aluminum and the second block is composed of copper.

[00171] In some embodiments, a non-transitory computer-readable storage medium having stored thereon data representing sequences of instructions that, when executed by a processor, cause the processor to perform operations including: starting a calibration program for a calibration operation; establishing communications with an actuator and a load cell of a calibration machine; receiving load cell and actuator data values; reading a force limit for the load cell and a position limit for the actuator; directing movement of the actuator for a calibration operation; and determining if a load cell value is outside of the load cell force limit or an actuator position value is outside of the actuator position limit, and, if so, stopping movement of the actuator.

[00172] In some embodiments, the medium further includes instructions for displaying the load cell and actuator data values.

[00173] In some embodiments, communicating with the actuator and load cell includes operation of a communication module. [00174] In some embodiments, reading load cell force and actuator position limits includes operation of a data acquisition module.

[00175] In some embodiments, directing movement of the actuator includes operation of an actuator control module.

[00176] In some embodiments, an apparatus includes: means for starting a calibration program for a calibration operation; means for establishing communications with an actuator and a load cell of a calibration machine; means for receiving load cell and actuator data values; means for reading a force limit for the load cell and a position limit for the actuator; means for directing movement of the actuator for a calibration operation; and means for determining if a load cell value is outside of the load cell force limit or an actuator position value is outside of the actuator position limit, and, if so, stopping movement of the actuator.

[00177] In some embodiments, the apparatus further includes means for displaying the load cell and actuator data values.

[00178] In some embodiments, communicating with the actuator and load cell includes operation of a communication module.

[00179] In some embodiments, reading load cell force and actuator position limits includes operation of a data acquisition module.

[00180] In some embodiments, directing movement of the actuator includes operation of an actuator control module.

Claims

CLAIMS What is claimed is:

1. A calibration machine comprising:

a base;

a first post and a second post, a first end of each of the posts being coupled with the base; a set of fixtures, a first fixture being coupled with the first post and second post and a second fixture being moveable coupled with the first post and the second post;

an actuator, the actuator being coupled with the first fixture and being operable to provide force on the second fixture;

a load cell coupled with the base; and

one or more calibration stages on the load cell and below the set of fixtures.

2. The calibration machine of claim 1 , further comprising at least one communication interface for communication with a control element.

3. The calibration machine of claim 2, wherein the actuator is to operate in response to received control commands.

4. The calibration machine of claim 2, wherein the actuator is to provide position information via the at least one communication interface.

5. The calibration machine of claim 1, wherein the load cell is to provide load data via the at least one communication interface.

6. The calibration machine of claim 1, wherein the one or more calibration stages includes a translational stage to translate a location for calibration and a rotational stage to rotate a position for calibration.

7. The calibration machine of claim 1 , further comprising a ball head coupled with the one or more fixtures to eliminate tilt during calibration.

8. The calibration machine of claim 1 , further comprising a vacuum suction assembly to hold a thermal solution for validating the measurements, the vacuum suction assembly including a plurality of suction cups to hold the thermal solution in place on the calibration machine.

9. A method comprising:

conditioning and equilibrating a piezoresistive pressure sensor; supporting the piezoresistive pressure sensor with one or more blocks; placing a sensel area of the piezoresistive pressure sensor on one or more silicon dies; mounting a thermal solution on the piezoresistive pressure sensor;

applying pressure to the thermal solution mounting unit with an actuator; and

acquiring calibration data for the piezoresistive pressure sensor during the application of pressure on the piezoresistive pressure sensor.

10. The method of claim 9, further comprising applying a thermal interface material (TIM) on the thermal solution prior to mounting the thermal solution on the piezoresistive pressure sensor.

11. The method of claim 10, wherein the TIM is a phase change material (PCM).

12. The method of claim 9, wherein the thermal solution is contained in a mounting unit.

13. The method of claim 9, wherein acquiring calibration data includes acquiring data during loading of the piezoresistive pressure sensor in which pressure applied to the sensor is increased.

14. The method of claim 9, further comprising:

placing the sensel area of the piezoresistive pressure sensor on a device under test;

placing a thermal solution on sensel area and attaching the thermal solution to the device under test; and

recording sensor readings from the piezoresistive pressure sensor, the sensor readings being adjusted based on the equilibration data and calibration data for the piezoresistive pressure sensor.

15. The method of claim 14, wherein the sensor readings provide quantitative data for load and pressure distribution resulting from attachment of the thermal solution.

16. The method of claim 9, wherein conditioning the piezoresistive pressure sensor includes applying a certain pressure to the piezoresistive pressure sensor and releasing the pressure a plurality of times.

17. The method of claim 16, wherein equilibrating the piezoresistive pressure sensor includes applying a series of increasing pressure values to the piezoresistive pressure sensor and obtaining equilibration data from the piezoresistive pressure sensor.

18. The method of claim 16, wherein the pressure is applied to the piezoresistive pressure sensor utilizing a pressure bladder.

19. The method of claim 16, wherein the conditioning and equilibrating of the piezoresistive pressure sensor includes automatic control of the application and release of pressure on the piezoresistive pressure sensor.

20. The method of claim 9, wherein supporting the piezoresistive pressure sensor with one or more blocks includes attaching the piezoresistive pressure sensor to a first block and placing the first block on a second block.

21. The method of claim 20, wherein the first metal block is composed of aluminum and the second block is composed of copper.

22. A non-transitory computer-readable storage medium having stored thereon data representing sequences of instructions that, when executed by a processor, cause the processor to perform operations comprising:

starting a calibration program for a calibration operation;

establishing communications with an actuator and a load cell of a calibration machine; receiving load cell and actuator data values;

reading a force limit for the load cell and a position limit for the actuator;

directing movement of the actuator for a calibration operation; and

determining if a load cell value is outside of the load cell force limit or an actuator position value is outside of the actuator position limit, and, if so, stopping movement of the actuator.

23. The medium of claim 22, further comprising instructions that, when executed by the processor, cause the processor to perform operations comprising:

displaying the load cell and actuator data values.

24. The medium of claim 22, wherein:

communicating with the actuator and load cell includes operation of a communication module; and

reading load cell force and actuator position limits includes operation of a data acquisition module.

25. The medium of claim 22, wherein directing movement of the actuator includes operation of an actuator control module.