The LLNL portion of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The Intel Corporation authors would like to thank Pilin Liu, Liang Hu, William Hammond, and Carlos Orduno from Intel Corporation for some of the data collection and helpful discussions. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Note: Protocol details described below were written specifically for work at beamline 8.3.2 at the ALS, Berkeley, CA. Adaptations may be required for work at other synchrotron facilities, which can be found around the world. Appropriate safety and radiation training is required for running experiments at these facilities and the guidelines for training can be found on each individual synchrotron facility&#39;s website. Any changes or updates to the tomography protocol (ALS, LBNL, Berkeley, CA) can be found on the beamline manual15. Details on the tomography process can be found in Reference16. The beamline scientists are available to answer any questions and will facilitate the experimental setup.
1. Steps for Performing Tomography Scans at Beamline 8.3.2 (ALS, LBNL)
<ol>
	<li>Prepare the sample for the scan by mounting it on a sample holder designed to fit in the beamline&#39;s rotational stage. For samples that do not have a custom mount, adhere the sample to a post or drill chuck with clay or wax. 
	Note: The sample scanned in this study was a microelectronic package that is 16 x 16 mm and only ~3 mm in height. In order to fit the entire package in the field of view the sample was mounted horizontally using clay provided at the beamline.
	<ol>
		<li>Align the sample to ensure that when it rotates through 180 degrees it stays within the field of view. Before loading the sample on the rotational stage inside the hutch there is an offline mock rotation stage that is used to align the sample. Visual inspection of the center of rotation is usually sufficient for the alignment.</li>
		<li>Mount the sample attached to the sample holder inside the hutch. Once the sample has been mounted in the hutch, two orthogonal centering motors allow positioning of the sample with respect to the center of rotation. 
		Note: Sometimes sample preparation is needed ahead of experiment time in order to make sure the sample size is correct for the desired resolution. For example, some of the 16 x 16 mm microelectronic packages were sectioned into smaller pieces for further high resolution scanning. The sample size can be determined using Tables 1 and 2.</li>
	</ol>
	</li>
	<li>Select the magnification for the scan based on the sample size and feature size of interest. Beamline 8.3.2 has several lenses to choose from which produce images with a range of pixel sizes from 0.35 - 9 &#181;m. Depending on the magnification, the sample must be of appropriate cross-sectional area, as the field of view decreases with increasing magnification.
	<ol>
		<li>Since the sample scanned here is 22.6 mm in the longest direction, select the 1X lens with the PCO.4,000, as shown in Tables 1 and 2, this combination gives the largest sample field of view. The resulting pixel size is 8.7 &#181;m.</li>
	</ol>
	</li>
	<li>Set the x-ray energy or switch to a polychromatic beam using the Beamline Control Computer. The x-ray energy range at beamline 8.3.2 is continuous from 4-80 keV, but the multilayer monochromator mounted limits the energy range to ~7-43 keV, while the peak flux occurs at ~12 keV. To get the best quality image, base the energy selection on targeting a ~30% transmission, which can be measured on the Data Acquisition Computer. In general, %Transmission increases with increasing energy.
	<ol>
		<li>For the microelectronic package, &#34;select white&#34; light due to the thickness and material of the package. 
		Note: The beamline 8.3.2 manual has detailed steps for changing between &#34;white&#34; light and monochromatic mode.</li>
		<li>When using &#34;white&#34; light mode, add 2-4 metal aluminum and copper filters in line with the x-ray beam in order to filter out the lower energy x-rays. For this sample, use 2 copper sheets with a total thickness of ~1.2 mm.</li>
		<li>Calculate transmission through the sample ahead of time by using: 
		http://henke.lbl.gov/optical_constants/filter2.html or http://www.nist.gov/pml/data/xraycoef/ or http://11bm.xray.aps.anl.gov/absorb/absorb.php. For example, inputting the chemical formula and estimated thickness for the sample will output a graph showing the percent transmission as a function of energy range.</li>
	</ol>
	</li>
	<li>Verify that the stage&#39;s center of rotation is aligned with the camera&#39;s center. To check that the sample is aligned rotate it through 180 degrees using software on the Beamline Control Computer and visually observe the change in sample location by viewing the radiographs on the computer. Control changes to alignment on the same computer. Image quality deteriorates when the sample&#39;s alignment is off enough so that regions of the sample leave the field of view during the sample rotation.</li>
	<li>Manually set sample to detector distance for scan. The camera is on a translational stage that can move horizontally which is used to change the sample to detector distance. When the distance increases the phase contrast contribution also increases. Phase effects are helpful to more easily image subtle cracks and edges, but also cause other &#34;halo effect&#34; artifacts that are often undesirable.</li>
	<li>Verify the beamline alignment. Check the focus of the image and adjust the focus motor if necessary. Confirm that the pixel size calibration is correct by moving the sample a defined amount and measuring the number of pixels the sample moved to calculate &#181;m/pixel. The voxel size will change depending on the experimental setup.
	<ol>
		<li>Check that as the image moves horizontally, image features track horizontally along a constant pixel, and if not, adjust the camera tilt motor so that they do. This aligns the axis of rotation so that it is parallel to pixel columns, which is the alignment assumed later by the reconstruction algorithms.</li>
	</ol>
	</li>
	<li>Select an exposure time for each radiograph. The range for exposure time is 1-1,500 msec and the selection depends on the scan energy and resolution (which determines the observed flux per resolution element). The selected time should provide a tradeoff between the quickest scan time and a scan with more counts and thus the best signal-to-noise ratio.
	<ol>
		<li>For the microelectronic package, use a sample scan time of 100 msec per exposure. 
		Note: Make sure there are no saturated pixels or at least less than the recommended target of 100. The control system is set to display camera counts on a converted scale so that each camera&#39;s maximum counts is 65,535.</li>
	</ol>
	</li>
	<li>Set up the Scan Parameters using the Data Acquisition Computer.
	<ol>
		<li>Input the desired angular range, and the number of images to collect over that range. The more angles selected the longer the scan times and larger the dataset size. Common numbers of angles are 513, 1,025, and 2,049 over a 0-180 degree range. For this study, use 1,025 angles over 180 degrees during data acquisition.</li>
		<li>Select the scanning mode. The two options for scanning mode are 1) normal and 2) continuous tomography. The continuous mode is preferred since it results in the shortest scan time, ~3 min. In this mode, the rotation stage continuously moves as images are collected. In normal mode, the rotation stage stops at each angle and then an image is collected.</li>
		<li>Specify number of bright and dark field images. The bright and dark field images are necessary for performing reconstruction. For the dark field images the shutters close and for the bright field or background images the samples moves out of the field of view. Verify that the sample is translated far enough so that it is not present in the bright field image in order to avoid large defects in the reconstructed images. Here, acquire 15 dark field images and 15 bright field images.</li>
		<li>Determine if tiling is necessary. If the sample is taller than the field of view there is a tiling option, which will scan the sample then translate it vertically until the entire sample is captured.</li>
	</ol>
	</li>
	<li>Execute run scan on the Data Acquisition Computer. The scan will run automatically based on the inputted settings.</li>
</ol>
2. Steps for Performing Tomographic Data Processing
<ol>
	<li>Transfer data to an analysis computer available at the beamline to perform the reconstruction and filtering of the data set using beamline protocol. Reconstruction can run independent of the data acquisition. 
	Note: Data is automatically transferred to NERSC, a high performance computer, where it is processed and reconstructed. Users can sign up for an account at NERSC to access their data through the SPOT Suite web portal at spot.nersc.gov. This portal is still in development mode, so many users prefer to have more control over the reconstruction parameters, in which case they follow the remaining steps.</li>
	<li>Reconstruct the raw images following these steps: 1) normalize images, 2) create stack of sinograms, 3) apply ring removal/filters, and 4) perform parallel beam reconstruction. The reconstruction is based on a filtered back projection algorithm. The reconstruction process results in TIFF images that contain information on the location and intensity of each pixel making up the sample volume. A schematic of the entire process is shown in Figure 2.
	<ol>
		<li>To access the plugin start FIJI (which is an acronym for Fiji Is Just ImageJ) and select the menu Plugins &#8594; ALSmicroCT &#8594; NormalizeStack832newnaming as shown below. A user at the ALS facility can perform the entire reconstruction process using a custom plugin for ImageJ/Fiji, which integrates several software packages designed to streamline the reconstruction process. 
		Note: Fiji and the plugin are available for use on multiple Beamline 8.3.2 analysis computers.</li>
		<li>Once the FIJI dialog box is open, as shown below, select the raw file intended for reconstruction. The stack of raw, bright, and dark images should now be loaded.</li>
		<li>Find the center of rotation by clicking &#39;Detect center of rotation&#39;, then to visualize the reconstructed image select &#39;Preview reconstruction&#39;. The value for center of rotation can also be inputted manually and previewed.</li>
		<li>Using this interface there is the option to change the ring removal parameters, the type of image (8, 16, or 32 bit), pixel range, rotation angle of images, and define cropped region. Each new parameter set can be visualized using the &#39;Preview reconstruction&#39; button.</li>
		<li>Once the parameters are selected, reconstruct the entire stack of images by selecting &#39;run&#39;. All the subsequent data files can be found in the specified &#39;Output directory&#39;, the default directory will be in an output file within the raw data folder.</li>
	</ol>
	</li>
	<li>Access raw data from tomography scans from any computer by going to the website http://spot.nersc.gov/, which is the NERSC (LBNL supercomputer) server through the SPOT portal. 
	Note: Each individual researcher must have their own NERSC account to access their specific datasets. A user can setup an account at https://nim.nersc.gov/nersc_account_request.php. At the beamline, each research group is assigned a beamline account. This account is used to access beamline computers, and can also be used to access data directly from the beamline server using Globus Online.</li>
	<li>Visualize the data in both 3D and 2D by loading the stack of 2D reconstructed images into any 3D analysis software. The samples and images presented here use Avizo software to perform the analysis and visualization, which is available to beamline users at any of the beamline 8.3.2 analysis computers.</li>
	<li>After a data set is uploaded into the visualization software perform further data analysis to get quantified information on specific features within the sample. Often datasets are downsampled in order to reduce the output data size. However this can increase the voxel size reducing fidelity, but smooth the image view for easier segmentation.
	<ol>
		<li>Select segment features of interest by thresholding the histogram of the stack of 2D reconstructed slices and assigning a new pixel value to pixels that fall within a specified range.</li>
		<li>Visualize segmented volumes and surfaces. Once features are segmented they are viewed in 3D using Avizo or any preferred visualization software. This allows for 3D surface renderings of specific features, like solder balls at a certain region of interest.</li>
		<li>Quantify features in sample, i.e., crack size, vias, porosity, defects, etc. Once a feature of interest is identified, such as a via or crack, the feature can be segmented and volumetric information on crack width, length, via volume, porosity distribution can be quantified by evaluating the tomographic data set.</li>
		<li>Create a movie of the sample showing the sample in different orientations. Movie 1 shows examples of the different cross-sectional views and volume rendering views for the microelectronic package imaged in the horizontal orientation.</li>
	</ol>
	</li>
</ol>

<ol>
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The authors have nothing to disclose.

All of the steps described in the protocol section are critical to obtaining high-resolution images of multi-scale and multi-material samples. One of the most critical steps is the sample mounting and the focusing of optics, which are vital to obtaining quality images that can be used for quantification. Specifically, even slight movement of the sample would cause artifacts in the reconstructed image and defocusing would cause deterioration in resolution. To avoid issues with image quality it is important to reconstruct ...

In the microelectronics field, as in many other fields, non-destructive evaluation at the micrometer scale is necessary when characterizing samples. Specifically for the microelectronics industry there is interest in probing 3D microelectronics packages, containing multi-levels and multi-materials, and identifying failures in packages during thermal, electrical, and mechanical stressing of components. Around the world synchrotron radiation facilities have designated tomography and diffraction beamlines that are used for failure analysis of microelectronic packages. Some examples of this are imaging void formation caused by electromigration1-3, evaluating mechanisms for tin whisker growth4,5, in situ observations of undercooling and anisotropic thermal expansion of tin and intermetallic compounds (IMCs)6,7, in situ observation of solidification and IMC formation8-10, anisotropic mechanical behavior and recrystallization of tin and lead free solders10, voids in flip chip bumps, and in situ observations of Ag-nanoink sintering11. All of these studies have further advanced the understanding and development of components in the microelectronic industry. However, many of these studies have focused on small regions within the package. More information could be gleaned from testing and characterizing the full size package using high resolution SR&#181;T in order to further their development.
The electronic packages being produced now contain multiple layers of interconnects. These packages and devices are growing more and more complex which calls for a 3D solution for non-destructive evaluation with regard to failure analysis, quality control, reliability risk assessment, and development. Certain defects require a technique that can detect features less than 5 &#181;m in size, which include voids and cracks forming inside copper substrate vias, identifying non-contact open and nonwet solder pads in multilevel packaging12, locating and quantifying voids in ball grid arrays (BGAs) and C4 solder joints. During the substrate assembly process these types of defects must be identified and monitored extensively to avoid unwanted failures.
Currently CT systems using laboratory-based sources, also known as tabletop, are able to provide as high as ~1 &#181;m spatial resolution, and are being used to isolate failures in multilevel packages with promising results. However, tabletop CT systems have some limitations when compared to SR&#181;T setups13,14. Tabletop systems are limited to only imaging a certain density range of materials since they usually only contain one or two x-ray source spectrums. Also through-put-time (TPT) remains long for conventional tabletop CT systems requiring several hours of data acquisition time per 1-2 mm2 region of interest, which can limit its usefulness; for instance, analyzing failures in Through Silicon Vias (TSV), BGAs or C4 joints often require acquiring multiple Field of Views (FoV) or regions of interest at high resolution within the sample, resulting in total TPT of 8-12 hours, which is a show stopper for conventional tabletop CT systems when multiple samples have to be analyzed. Synchrotron radiation provides much higher flux and brightness than conventional x-ray sources, resulting in much faster data acquisition times for a given region of interest. Although SR&#181;T does allow for more flexibility with respect to types of materials that can be imaged and sample volume, it does have limitations, which are specific to the synchrotron source and setup used, specifically maximum acceptable thickness and sample size. For the SR&#181;T setup at the ALS the maximum cross-sectional area that can be imaged is &#60;36 x 36 mm and the thickness is limited by the energy range and flux available and is material specific.
This study is used to demonstrate how SR&#181;T can be utilized to image an entire multi-level system in package (SIP) with high resolution and low TPT (3-20 min) for use in inspecting 3D semiconductor packages. More details on comparing tabletop CT&#39;s to Synchrotron Source CT&#39;s can be found in references13,14.
Experimental Overview &#38; Beamline 8.3.2 Description: 
There are synchrotron facilities available for tomography experiments around the world; most of these facilities require submission of a proposal where the experimentalist describes the experiment, as well as its scientific impact. The experiments described here were all performed at the ALS at Lawrence Berkeley National Laboratory (LBNL) at beamline 8.3.2. For this beamline there are two energy mode options: 1) monochromatic in the energy range ~7-43 keV or 2) polychromatic &#34;white&#34; light where the entire available energy spectrum is used when scanning high density materials. During a typical scan at beamline 8.3.2 a sample is mounted on a rotational stage where x-rays penetrate the sample, then the attenuated x-rays are converted into visible light through a scintillator, magnified by a lens, and then projected onto a CCD for recording. This is done while the sample rotates from 0 to 180&#176; producing a stack of images that is reconstructed to obtain a 3D view of the sample with micrometer resolution. The resulting tomographic dataset size ranges from ~3-20 Gb depending on the scan parameters. Figure 1 shows a schematic of the hutch where the sample is scanned.
The following protocol presented here describes the experimental setup, data acquisition, and processing steps required for imaging an entire microelectronic package, but the steps can be modified to image a variety of samples. The modifications depend on the sample size, density, geometries, and features of interest. Tables 1 and 2 present the resolution and sample size combinations available at beamline 8.3.2 (ALS, LBNL, Berkeley, CA). For the microelectronic package investigated here the sample was imaged using a polychromatic (&#34;white&#34;) beam, which was selected due to the thickness and high-density of the sample&#39;s components. The sample was mounted in the horizontal orientation on a chuck mount, this orientation allowed for the entire sample to fit within the height of the beam, which is parallel with a height of ~4 mm and width of ~40 mm, therefore only requiring one scan to capture the entire sample.

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	<tbody>
		<tr height="20">
			<td class="xl64" height="20" style="height:15.0pt;width:87pt" width="116">Beamline 8.3.2</td>
			<td class="xl64" style="width:200pt" width="267">Advanced Light Source, Berkeley, CA, USA</td>
			<td style="width:81pt" width="108"></td>
			<td class="xl65" style="width:113pt" width="150">http://microct.lbl.gov/</td>
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using synchrotron radiation microtomography to investigate multi-scale three-dimensional microelectronic packages

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data acquisition times with high spatial resolution. In the electronics industry there is serious interest in performing failure analysis on 3D microelectronic packages, many which contain multiple levels of high-density interconnections. Often in tomography there is a trade-off between image resolution and the volume of a sample that can be imaged. This inverse relationship limits the usefulness of conventional computed tomography (CT) systems since a microelectronic package is often large in cross sectional area 100-3,600 mm2, but has important features on the micron scale. The micro-tomography beamline at the Advanced Light Source (ALS), in Berkeley, CA USA, has a setup which is adaptable and can be tailored to a sample&#39;s properties, i.e., density, thickness, etc., with a maximum allowable cross-section of 36 x 36 mm. This setup also has the option of being either monochromatic in the energy range ~7-43 keV or operating with maximum flux in white light mode using a polychromatic beam. Presented here are details of the experimental steps taken to image an entire 16 x 16 mm system within a package, in order to obtain 3D images of the system with a spatial resolution of 8.7 &#181;m all within a scan time of less than 3 min. Also shown are results from packages scanned in different orientations and a sectioned package for higher resolution imaging. In contrast a conventional CT system would take hours to record data with potentially poorer resolution. Indeed, the ratio of field-of-view to throughput time is much higher when using the synchrotron radiation tomography setup. The description below of the experimental setup can be implemented and adapted for use with many other multi-materials.

The images captured using tomography occur due to the differential absorption of x-rays in the solder interconnects, metallic traces, and other materials in the microelectronic package as a function of the different attenuation lengths and thickness of these multi-materials. The SIP package consisted of a silicon die attached to a ceramic substrate with first level interconnect (FLI) flip chip C4 solder balls of approximately 80 &#181;m diameter; mid-level interconnect (MLI) solder balls of approximately 350 &#181;m conn...

Watch this Scientific Journal Video about Using Synchrotron Radiation Microtomography to Investigate Multi-scale Three-dimensional Microelectronic Packages at JoVE.com

Using Synchrotron Radiation Microtomography to Investigate Multi-scale Three-dimensional Microelectronic Packages

For this study synchrotron radiation micro-tomography, a non-destructive three-dimensional imaging technique, is employed to investigate an entire microelectronic package with a cross-sectional area of 16 x 16 mm. Due to the synchrotron&#39;s high flux and brightness the sample was imaged in just 3 min&#160;with an 8.7 &#181;m spatial resolution.

Synchrotron radiation micro-tomography (SR&#181;T) is a non-destructive three-dimensional (3D) imaging technique that offers high flux for fast data ...

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10.0K Views.  Lawrence Livermore National Laboratory. For this study synchrotron radiation micro-tomography, a non-destructive three-dimensional imaging technique, is employed to investigate an entire microelectronic package with a cross-sectional area of 16 x 16 mm. Due to the synchrotron's high flux and brightness the sample was imaged in just 3 min with an 8.7 µm spatial resolution.

Video: Using Synchrotron Radiation Microtomography to Investigate Multi-scale Three-dimensional Microelectronic Packages

Molecular Beam Mass Spectrometry With Tunable Vacuum Ultraviolet (VUV) Synchrotron Radiation

Tunable soft ionization coupled to mass spectroscopy is a powerful method to investigate isolated molecules, complexes and clusters and their spectroscopy and dynamics1-4. Fundamental studies of photoionization processes of biomolecules provide information about the electronic structure of these systems. Furthermore determinations of ionization energies and other properties of biomolecules in the gas phase are not trivial, and these experiments provide a platform to generate these data. We have developed a thermal vaporization technique coupled with supersonic molecular beams that provides a gentle way to transport these species into the gas phase. Judicious combination of source gas and temperature allows for formation of dimers and higher clusters of the DNA bases. The focus of this particular work is on the effects of non-covalent interactions, i.e., hydrogen bonding, stacking, and electrostatic interactions, on the ionization energies and proton transfer of individual biomolecules, their complexes and upon micro-hydration by water1, 5-9.
We have performed experimental and theoretical characterization of the photoionization dynamics of gas-phase uracil and 1,3-dimethyluracil dimers using molecular beams coupled with synchrotron radiation at the Chemical Dynamics Beamline10 located at the Advanced Light Source and the experimental details are visualized here. This allowed us to observe the proton transfer in 1,3-dimethyluracil dimers, a system with pi stacking geometry and with no hydrogen bonds1. Molecular beams provide a very convenient and efficient way to isolate the sample of interest from environmental perturbations which in return allows accurate comparison with electronic structure calculations11, 12. By tuning the photon energy from the synchrotron, a photoionization efficiency (PIE) curve can be plotted which informs us about the cationic electronic states. These values can then be compared to theoretical models and calculations and in turn, explain in detail the electronic structure and dynamics of the investigated species 1, 3.

Molecular Beam Mass Spectrometry With Tunable Vacuum Ultraviolet VUV Synchrotron Radiation

A molecular beam coupled to tunable vacuum ultraviolet photoionization mass spectrometer at a synchrotron provides a convenient tool to explore the electronic structure of isolated gas phase molecules and clusters. Proton transfer mechanisms in DNA base dimers were elucidated with this technique.

Tunable soft ionization coupled to mass spectroscopy is a powerful method to investigate isolated molecules, complexes and clusters and their spectroscopy ...

High-resolution, High-speed, Three-dimensional Video Imaging with Digital Fringe Projection Techniques

Digital fringe projection (DFP) techniques provide dense 3D measurements of dynamically changing surfaces.&#160;Like the human eyes and brain, DFP uses triangulation between matching points in two views of the same scene at different angles to compute depth.&#160;However, unlike a stereo-based method, DFP uses a digital video projector to replace one of the cameras1. The projector rapidly projects a known sinusoidal pattern onto the subject, and the surface of the subject distorts these patterns in the camera&#8217;s field of view. Three distorted patterns (fringe images) from the camera can be used to compute the depth using triangulation.
Unlike other 3D measurement methods, DFP techniques lead to systems that tend to be faster, lower in equipment cost, more flexible, and easier to develop.&#160;DFP systems can also achieve the same measurement resolution as the camera.&#160;For this reason, DFP and other digital structured light techniques have recently been the focus of intense research (as summarized in1-5). Taking advantage of DFP, the graphics processing unit, and optimized algorithms, we have developed a system capable of 30&#160;Hz 3D video data acquisition, reconstruction, and display for over 300,000 measurement points per frame6,7.&#160;Binary defocusing DFP methods can achieve even greater speeds8.
Diverse applications can benefit from DFP techniques. Our collaborators have used our systems for facial function analysis9, facial animation10, cardiac mechanics studies11, and fluid surface measurements, but many other potential applications exist.&#160;This video will teach the fundamentals of DFP techniques and illustrate the design and operation of a binary defocusing DFP system.

This video describes the fundamentals of digital fringe projection techniques, which provide dense 3D measurements of dynamically changing surfaces.&#160;It also demonstrates the design and operation of a high-speed binary defocusing system based on these techniques.

Digital fringe projection (DFP) techniques provide dense 3D measurements of dynamically changing surfaces.&#160;Like the human eyes and brain, DFP uses ...

Process of Making Three-dimensional Microstructures using Vaporization of a Sacrificial Component

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material fabrication techniques are able to mimic the complexity of these structures while maintaining scalability. The Vaporization of a Sacrificial Component (VaSC) process is able to do so. This process uses sacrificial fibers as a template to form hollow, cylindrical microchannels embedded within a matrix. Tin (II) oxalate (SnOx) is embedded within poly(lactic) acid (PLA) fibers which facilitates the use of this process. The SnOx catalyzes the depolymerization of the PLA fibers at lower temperatures. The lactic acid monomers are gaseous at these temperatures and can be removed from the embedded matrix at temperatures that do not damage the matrix. Here we show a method for aligning these fibers using micromachined plates and a tensioning device to create complex patterns of three-dimensionally arrayed microchannels. The process allows the exploration of virtually any arrangement of fiber topologies and structures.

The Vaporization of a Sacrificial Component (VaSC) process is used to fabricate microvascular structures. This procedure uses sacrificial poly(lactic) acid fibers to form hollow microchannels with precise 3D geometric positioning provided by laser micromachined guide plates.

Vascular structures in natural systems are able to provide high mass transport through high surface areas and optimized structure. Few synthetic material ...

Characterization of Electrode Materials for Lithium Ion and Sodium Ion Batteries Using Synchrotron Radiation Techniques

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. During insertion or removal of alkali metal ions, the redox states of transition metals in the compounds change and structural transformations such as phase transitions and/or lattice parameter increases or decreases occur. These behaviors in turn determine important characteristics of the batteries such as the potential profiles, rate capabilities, and cycle lives. The extremely bright and tunable x-rays produced by synchrotron radiation allow rapid acquisition of high-resolution data that provide information about these processes. Transformations in the bulk materials, such as phase transitions, can be directly observed using X-ray diffraction (XRD), while X-ray absorption spectroscopy (XAS) gives information about the local electronic and geometric structures (e.g.&#160;changes in redox states and bond lengths). In situ experiments carried out on operating cells are particularly useful because they allow direct correlation between the electrochemical and structural properties of the materials. These experiments are time-consuming and can be challenging to design due to the reactivity and air-sensitivity of the alkali metal anodes used in the half-cell configurations, and/or the possibility of signal interference from other cell components and hardware. For these reasons, it is appropriate to carry out ex situ experiments (e.g.&#160;on electrodes harvested from partially charged or cycled cells) in some cases. Here, we present detailed protocols for the preparation of both ex situ and in situ samples for experiments involving synchrotron radiation and demonstrate how these experiments are done.

We describe the use of synchrotron X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) techniques to probe details of intercalation/deintercalation processes in electrode materials for Li-ion and Na-ion batteries. Both in situ and ex situ experiments are used to understand structural behavior relevant to the operation of devices

Intercalation compounds such as transition metal oxides or phosphates are the most commonly used electrode materials in Li-ion and Na-ion batteries. ...

Using Neutron Spin Echo Resolved Grazing Incidence Scattering to Investigate Organic Solar Cell Materials

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped crystallites. Neutrons are passed through two well defined regions of magnetic field; one before and one after the sample. The two magnetic field regions have opposite polarity and are tuned such that neutrons travelling through both regions, without being perturbed, will undergo the same number of precessions in opposing directions. In this case the neutron precession in the second arm is said to &#34;echo&#34; the first, and the original polarization of the beam is preserved. If the neutron interacts with a sample and scatters elastically the path through the second arm is not the same as the first and the original polarization is not recovered. Depolarization of the neutron beam is a highly sensitive probe at very small angles (&#60;50&#160;&#956;rad) but still allows a high intensity, divergent beam to be used. The decrease in polarization of the beam reflected from the sample as compared to that from the reference sample can be directly related to structure within the sample.
In comparison to scattering observed in neutron reflection measurements the SERGIS signals are often weak and are unlikely to be observed if the in-plane structures within the sample under investigation are dilute, disordered, small in size and polydisperse or the neutron scattering contrast is low. Therefore, good results will most likely be obtained using the SERGIS technique if the sample being measured consist of thin films on a flat substrate and contain scattering features that contains a high density of moderately sized features (30 nm to 5 &#181;m) which scatter neutrons strongly or the features are arranged on a lattice. An advantage of the SERGIS technique is that it can probe structures in the plane of the sample.

Progress has been made in utilizing spin echo resolved grazing incidence scattering (SERGIS) as a neutron scattering technique to probe the length-scales in irregular samples. Crystallites of [6,6]-phenyl-C61-butyric acid methyl ester have been probed using the SERGIS technique and the results confirmed by optical and atomic force microscopy.

The spin echo resolved grazing incidence scattering (SERGIS) technique has been used to probe the length-scales associated with irregularly shaped ...

Reservoir Condition Pore-scale Imaging of Multiple Fluid Phases Using X-ray Microtomography

X-ray microtomography was used to image, at a resolution of 6.6 &#181;m, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space of a carbonate rock at pressures and temperatures representative of typical formations used for CO2 storage. Chemical equilibrium between the CO2, brine and rock phases was maintained using a high pressure high temperature reactor, replicating conditions far away from the injection site. Fluid flow was controlled using high pressure high temperature syringe pumps. To maintain representative in-situ conditions within the micro-CT scanner a carbon fiber high pressure micro-CT coreholder was used. Diffusive CO2 exchange across the confining sleeve from the pore-space of the rock to the confining fluid was prevented by surrounding the core with a triple wrap of aluminum foil. Reconstructed brine contrast was modeled using a polychromatic x-ray source, and brine composition was chosen to maximize the three phase contrast between the two fluids and the rock. Flexible flow lines were used to reduce forces on the sample during image acquisition, potentially causing unwanted sample motion, a major shortcoming in previous techniques. An internal thermocouple, placed directly adjacent to the rock core, coupled with an external flexible heating wrap and a PID controller was used to maintain a constant temperature within the flow cell. Substantial amounts of CO2 were trapped, with a residual saturation of 0.203 &#177; 0.013, and the sizes of larger volume ganglia obey power law distributions, consistent with percolation theory.

We present a methodology for the imaging of multiple fluid phases at reservoir conditions by the use of x-ray microtomography. We show some representative results of capillary trapping in a carbonate rock sample.

X-ray microtomography was used to image, at a resolution of 6.6 &#181;m, the pore-scale arrangement of residual carbon dioxide ganglia in the pore-space ...

Failure Analysis of Batteries Using Synchrotron-based Hard X-ray Microtomography

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent of lithium-ion batteries, researchers have known that the lithium metal anode has the highest theoretical energy density of any anode material. However, rechargeable batteries containing a lithium metal anode are not widely used in consumer products because the growth of lithium dendrites from the anode upon charging of the battery causes premature cell failure by short circuit. Lithium dendrites can also form in commercial lithium-ion batteries with graphite anodes if they are improperly charged. We demonstrate that lithium dendrite growth can be studied using synchrotron-based hard X-ray microtomography. This non-destructive imaging technique allows researchers to study the growth of lithium dendrites, in addition to other morphological changes inside batteries, and subsequently develop methods to extend battery life.

Synchrotron-based hard X-ray microtomography is used to image the electrochemical growth of dendrites from a lithium metal electrode through a solid polymer electrolyte membrane.

Imaging morphological changes that occur during the lifetime of rechargeable batteries is necessary to understand how these devices fail. Since the advent ...

Three-dimensional Particle Tracking Velocimetry for Turbulence Applications: Case of a Jet Flow

3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic recording of image sequences. The basic components, features, constraints and optimization tips of a 3D-PTV topology consisting of a high-speed camera with a four-view splitter are described and discussed in this article. The technique is applied to the intermediate flow field (5 &#60;x/d &#60;25) of a circular jet at Re &#8776; 7,000. Lagrangian flow features and turbulence quantities in an Eulerian frame are estimated around ten diameters downstream of the jet origin and at various radial distances from the jet core. Lagrangian properties include trajectory, velocity and acceleration of selected particles as well as curvature of the flow path, which are obtained from the Frenet-Serret equation. Estimation of the 3D velocity and turbulence fields around the jet core axis at a cross-plane located at ten diameters downstream of the jet is compared with literature, and the power spectrum of the large-scale streamwise velocity motions is obtained at various radial distances from the jet core.

A three-dimensional particle tracking velocimetry (3D-PTV) system based on a high-speed camera with a four-view splitter is described here. The technique is applied to a jet flow from a circular pipe in the vicinity of ten diameters downstream at Reynolds number Re &#8776; 7,000.

3D-PTV is a quantitative flow measurement technique that aims to track the Lagrangian paths of a set of particles in three dimensions using stereoscopic ...

Dynamic Pore-scale Reservoir-condition Imaging of Reaction in Carbonates Using Synchrotron Fast Tomography

Underground storage permanence is a major concern for carbon capture and storage. Pumping CO2 into carbonate reservoirs has the potential to dissolve geologic seals and allow CO2 to escape. However, the dissolution processes at reservoir conditions are poorly understood. Thus, time-resolved experiments are needed to observe and predict the nature and rate of dissolution at the pore scale. Synchrotron fast tomography is a method of taking high-resolution time-resolved images of complex pore structures much more quickly than traditional &#181;-CT. The Diamond Lightsource Pink Beam was used to dynamically image dissolution of limestone in the presence of CO2-saturated brine at reservoir conditions. 100 scans were taken at a 6.1 &#181;m resolution over a period of 2 hours. The images were segmented and the porosity and permeability were measured using image analysis and network extraction. Porosity increased uniformly along the length of the sample; however, the rate of increase of both porosity and permeability slowed at later times.

Synchrotron fast tomography was used to dynamically image dissolution of limestone in the presence of CO2-saturated brine at reservoir conditions. 100 scans were taken at a 6.1 &#181;m resolution over a period of 2 h.

Underground storage permanence is a major concern for carbon capture and storage. Pumping CO2 into carbonate reservoirs has the potential to dissolve ...

The Evolution of Silica Nanoparticle-polyester Coatings on Surfaces Exposed to Sunlight

Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, building and food industries, amongst others. Polyester and coatings containing both polyester and silica nanoparticles (SiO2NPs) have been widely used to protect steel substrata from corrosion. In this study, we utilized X-ray photoelectron spectroscopy, attenuated total reflection infrared micro-spectroscopy, water contact angle measurements, optical profiling and atomic force microscopy to provide an insight into how exposure to sunlight can cause changes in the micro- and nanoscale integrity of the coatings. No significant change in surface micro-topography was detected using optical profilometry, however, statistically significant nanoscale changes to the surface were detected using atomic force microscopy. Analysis of the X-ray photoelectron spectroscopy and attenuated total reflection infrared micro-spectroscopy data revealed that degradation of the ester groups had occurred through exposure to ultraviolet light to form COO&#903;, -H2C&#903;, -O&#903;, -CO&#903; radicals. During the degradation process, CO and CO2 were also produced.

Two types of surfaces, polyester-coated steel and polyester coated with a layer of silica nanoparticles, were studied. Both surfaces were exposed to sunlight, which was found to cause substantial changes in the chemistry and nanoscale topography of the surface.