Tuesday, 25 September 2018

Non-Destructive Fault Localization in Fan Out Wafer Level Packages Using Electro Optical Terahertz Pulse Reflectometry

Rho, Kyungsoo, Jongmin Lee, Daejin Kim, Thomas White, and Jesse Alton. "Non-Destructive Fault Localization in Fan Out Wafer Level Packages Using Electro Optical Terahertz Pulse Reflectometry." In 2018 IEEE International Symposium on the Physical and Failure Analysis of Integrated Circuits (IPFA), pp. 1-4. IEEE, 2018.

Here, we demonstrate how electro optical terahertz pulse refiectometry (EOTPR), a time-domain refiectometry technique that utilizes terahertz frequency electrical pulses to identify device faults, can be used to quickly and non-destructively isolate faults in advanced fan-out wafer level (FOWL) packages. We present a case study to show how EOTPR can accurately locate faults in the densely spaced redistribution layers (RDLs) of the package.

For more information about TeraView see www.teraview.com

Monday, 24 September 2018

Study of plant fibre composites with damage induced by laser and mechanical impacts

Malinowski, Paweł H., Wiesław M. Ostachowicz, Fabienne Touchard, Michel Boustie, Laurence Chocinski-Arnault, Pedro Pascual Gonzalez, Laurent Berthe, Davi Silva de Vasconcellos, and Luigi Sorrentino. "Study of plant fibre composites with damage induced by laser and mechanical impacts." Composites Part B: Engineering 152 (2018): 209-219.

Polymer composite materials provide good strength to weight ratio and tailored mechanical properties thanks to the reinforcing fibres. Until recently, the need for taking into account the whole life cycle of a composite structure was neglected and only the service aspects were important. Today, the designers of a new composite structure have to take into account the environmental aspects from the sustainability of raw materials to the management of end life products. There are recycling issues related to the most popular composites. A solution for the recycling issue can be sought in green composites with reinforcing fibre originating from plants. The behaviour of eco-composites, when subjected to laser or mechanical impactloadings, is not well known yet. Short fibre composites were made with spruce fibres. Another set of samples was made of flax fibres. Also a woven hemp fabric-based eco-composite was investigated. A fully synthetic woven composite was used for comparison with green composites. Mechanical impacts were performed by means of a falling dart impact testing machine. Laser impacts were made with high power laser source. Four assessment techniques were employed in order to analyse and compare impact damage. Damage detection thresholds for each material and technique were obtained.
… The terahertz spectrometer used was TPS Spectra 3000 from TeraView (Cambridge, United Kingdom) with radiation in the 0.1–3 THz range. The spectrometer is equipped with a moving table to apply xy movements and scan large objects (Fig … 

For more information about TeraView see www.teraview.com

Terahertz Multivariate Spectral Analysis and Molecular Dynamics Simulations of Three Pyrethroid Pesticides

Qu, Fangfang, Lei Lin, Yong He, Pengcheng Nie, Chengyong Cai, Tao Dong, Yi Pan, Yu Tang, and Shaoming Luo. "Terahertz Multivariate Spectral Analysis and Molecular Dynamics Simulations of Three Pyrethroid Pesticides." Journal of Infrared, Millimeter, and Terahertz Waves (2018): 1-14.


The terahertz (THz) multivariate spectral characteristics and the molecular dynamics of three pyrethroid pesticides, including deltamethrin, fenvalerate, and beta-cypermethrin, were studied in this paper. THz spectra of the pesticides were measured in frequency range of 0.06–3.5 THz by using THz time-domain spectroscopy (THz-TDS). To improve the THz spectral quality, the wavelet threshold de-noising (WTD) method was used to remove spectral noise and the spectral baseline correction (SBC) method was used to remove baseline drift. Specific absorption peaks were observed in the processed THz spectra of the three pesticides. Deltamethrin showed three peaks at 0.90, 1.49, and 2.32 THz. Fenvalerate had five peaks at 1.13, 1.43, 1.61, 1.98, and 2.58 THz. Beta cypermethrin had four peaks at 1.27, 1.84, 2.12, and 2.92 THz. The density functional theory (DFT) was used to characterize the molecular dynamics and formation mechanism of the absorption peaks. Results showed that there was a good matching effect between the THz experimental spectra and the DFT quantum calculation spectra. Based on the characterized fingerprint absorption peaks, the linear addition model was used to simulate the THz spectra of mixed pesticides. The simulated spectra of multicomponent pesticides were demonstrated to be in good agreement with those obtained by THz-TDS. By analyzing the absorption peaks of THz spectra, the composition and concentration of multicomponent pesticides could be determined. The proposed strategy presented an analytical methodology for studying the THz spectral characteristics of pesticides. In addition, this work provided experimental and theoretical basis for the detection potential of pesticides in agricultural products based on THz technology. 

… 2.2 THz Spectral Acquisition The TeraPulse 4000 THz-TDS system, Inc. (Teraview, UK), was applied to the spectral acquisition of the pesticide....

For more information about TeraView see www.teraview.com

Tuesday, 4 September 2018

Dynamic Photoinduced Controlling of the Large Phase Shift of Terahertz Waves via Vanadium Dioxide Coupling Nanostructures

Zhao, Yuncheng, Yaxin Zhang, Qiwu Shi, Shixiong Liang, Wanxia Huang, Wei Kou, and Ziqiang Yang. "Dynamic Photoinduced Controlling of the Large Phase Shift of Terahertz Waves via Vanadium Dioxide Coupling Nanostructures." ACS Photonics 5, no. 8 (2018): 3040-3050.

for full paper see https://pubs.acs.org/doi/abs/10.1021/acsphotonics.8b00276

… THz-TDS). The THz-TDS system is produced by Teraview company (Teraview TPS 3000). In this system, the Terahertz transmitter and detector are laser gated photo-conductive semiconductor devices. The femtosecond pulse … 


Abstract Image
Utilizing terahertz (THz) waves to transmit data for communication and imaging places high demands on phase modulation. However, until now, it is difficult to realize a more than 100° phase shift in the transmission mode with one-layer structure. In this paper, a ring-dumbbell composite resonator nested with VO2 nanostructures is proposed to achieve the large phase shift. It is found that in this structure a hybrid mode with an enhanced resonant intensity, which is coupled by the L-C resonance and dipole resonance has been observed. Applying the photoinduced phase transition characteristics of VO2, the resonant intensity of the mode can be dynamically controlled, which leads to a large phase shift in the incident THz wave. The dynamic experimental results show that controlling the power of the external laser can achieve a phase shift of up to 138° near 0.6 THz using this one-layer VO2 nested composite structure. Moreover, within a 55 GHz (575–630 GHz) bandwidth, the phase shift exceeds 130°. This attractive phase shift modulation may provide prospective applications in THz imaging, communications, and so on.

Monday, 3 September 2018

Assessment of Terahertz Imaging for Excised Breast Cancer Tumors with Image Morphing

Chavez, Tanny, Tyler Bowman, Jingxian Wu, Keith Bailey, and Magda El-Shenawee. "Assessment of Terahertz Imaging for Excised Breast Cancer Tumors with Image Morphing." Journal of Infrared, Millimeter, and Terahertz Waves (2018): 1-20.
This paper presents an image morphing algorithm for quantitative evaluation methodology of terahertz (THz) images of excised breast cancer tumors. Most current studies on the assessment of THz imaging rely on qualitative evaluation, and there is no established benchmark or procedure to quantify the THz imaging performance. The proposed morphing algorithm provides a tool to quantitatively align the THz image with the histopathology image. Freshly excised xenograft murine breast cancer tumors are imaged using the pulsed THz imaging and spectroscopy system in the reflection mode. Upon fixing the tumor tissue in formalin and embedding in paraffin, a formalin-fixed paraffin-embedded (FFPE) tissue block is produced. A thin slice of the block is prepared for the pathology image while another THz reflection image is produced directly from the block. We developed an algorithm of mesh morphing using homography mapping of the histopathology image to adjust the alignment, shape, and resolution to match the external contour of the tissue in the THz image. Unlike conventional image morphing algorithms that rely on internal features of the source and target images, only the external contour of the tissue is used to avoid bias. Unsupervised Bayesian learning algorithm is applied to THz images to classify the tissue regions of cancer, fat, and muscles present in xenograft breast tumors. The results demonstrate that the proposed mesh morphing algorithm can provide more effective and accurate evaluation of THz imaging compared with existing algorithms. The results also showed that while THz images of FFPE tissue are highly in agreement with pathology images, challenges remain in assessing THz imaging of fresh tissue.
Funding Information
This work was funded by the National Institutes of Health under Award No. R15CA208798. It was also funded in part by the National Science Foundation under Award Nos. 1408007 and 1711087.
… 2 Pulsed THz Imaging and Spectroscopy System The THz system is a TPS Spectra 3000 (#TeraView, Ltd.) pulsed terahertz imaging and spectroscopy system at the #University of Arkansas [5–8]. A diagram of the system is given in Fig …