Software Structure Research Articles

Quasi-Distributed Temperature Detection of Press-Pack IGBT Power Module Using FBG Sensing

In situ temperature near the chips in a multiple-chip power semiconductor module is important information for thermal design validation, condition monitoring, and overheat protection. Due to the compact packaging structure and clamping force, online detection of the temperature is challenging for a press-pack module. This study attempts to achieve measurement by integrating optical fiber Bragg grating (FBG) sensors into the device. Different integration schemes are examined using experiments and theoretical analysis to show the effects on the transient performance. It is shown that FBG sensors with plate housing can effectively indicate the transient temperature ripple in normal converter operation, owing to the fast dynamic response of a small size sensor. The package integration has only minimal effects on the original distributions of electrical, thermal, and mechanical quantities within the power module.

A package for piezoresistive pressure sensors with embedded built-in self-test function based on bimetallic actuator

Piezoresistive pressure sensors have been widely used in the industry and many other fields. However, conventional pressure sensor inspection is performed with the device off, which causes several inconveniences. In this article, an electrothermal actuator is designed and fabricated on the basis of bimetallic alloy material to realise the self-test of the piezoresistive silicon pressure sensor, and a kind of pressure sensor package structure with self-test capability is developed using the electrothermal actuator. Experimental results show that the structure can realise the dual excitation of the pressure and temperature of the diffused silicon pressure sensor core and enable it to return to the normal working state in less than 3.3 s. The self-test module can be driven at a low voltage of 0.8 V at less than 618 mW and can reflect the performance of the pressure sensor quickly and accurately. The structure is suitable for most differential pressure, absolute pressure sensor chips.

Anisotropic highly conductive joints utilizing Cu-solder microcomposite structure for high-temperature electronics packaging

The miniaturization of power conversion systems requires high-power density operation of power modules, causing the heat-density increase. Therefore, it is essential to develop bonding technology to realize highly thermally conductive and reliable high-temperature joints. In this study, we propose a novel anisotropic microcomposite (AMC) joint that integrates a lotus-type porous Cu (LPC) sheet and Sn-based solder for high-temperature electronic applications. The AMC joint was successfully fabricated by infiltrating the molten solder into the unidirectional pores of the LPC sheet during a simple reflow process. Steady-state thermal conductivity measurements for a uniquely designed specimen revealed its equivalent thermal conductivity (142.4 W/m·K), 2.5 times higher than the solder. Finite element simulations supported its excellent thermal performance by investigating the heat flux distribution and thermal conductivity prediction that utilize a three-dimensional image-based constructed model. In addition, the aging test at 200 °C for 1008 h clarified a stable shear strength of over 46 MPa. This indicates a reliable mechanical performance at 200 °C, which is only 20 °C below the melting point of the solder. These experimental and numerical studies proved the potential of the novel joint as a high-temperature electronics joint and offered possible mechanisms for its thermal and mechanical property enhancement.

Enhanced High-Rate Capability and Long Cycle Stability of FeS@NCG Nanofibers for Sodium-Ion Battery Anodes.

The development of advanced hierarchical anode materials has recently become essential to achieving high-performance sodium-ion batteries. Herein, we developed a facile and cost-effective scheme for synthesizing graphene-wrapped, nitrogen-rich carbon-coated iron sulfide nanofibers (FeS@NCG) as an anode for SIBs. The designed FeS@NCG can provide a significant reversible capacity of 748.5 mAh g-1 at 0.3 A g-1 for 50 cycles and approximately 3.9-fold higher electrochemical performance than its oxide analog (Fe2O3@NCG, 192.7 mAh g-1 at 0.3 A g-1 for 50 cycles). The sulfur- and nitrogen-rich multilayer package structure facilitates efficient suppression of the porous FeS volume expansion during the sodiation process, enabling a long cycle life. The intimate contact between graphene and porous carbon-coated FeS nanofibers offers strong structural barriers associated with charge-transfer pathways during sodium insertion/extraction. It also reduces the dissolution of polysulfides, enabling efficient sodium storage with superior stable kinetics. Furthermore, outstanding capacity retention of 535 mAh g-1 at 5 A g-1 is achieved over 1010 cycles. The FeS@NCG also exhibited a specific capacity of 640 mAh g-1 with a Coulombic efficiency of above 99.8% at 5 A g-1 at 80 °C, indicating its development prospects in high-performance SIB applications.

Application of 3D Digital Image Processing Technology in Modern Packaging Design

In this paper, a modern packaging model is constructed by combining three-dimensional digital image processing technology, which has achieved the effect of improving the quality of modern packaging design. In addition, this paper proposes a new target recognition and tracking scheme, which uses the method of servo motor to control the synchronous conveyor belt to monitor the moving objects in real time and proposes a decision analysis algorithm to avoid repeated identification of multiple moving targets. At the same time, the software structure and execution flow of the visual control system are designed, the level of each functional module of the software is divided, and the key technology of the software is studied. The experimental research shows that the 3D digital image processing technology is effective in improving modern packaging design methods and can improve the interactivity and user experience of modern packaging design.

Satellite-borne atomic clock based on diffuse laser-cooled atoms

The technique of laser cooling of atoms gives an opportunity to improve the performance of atomic clocks by using laser-cooled atoms. The most successful cold atom clock, called the atomic fountain, is now widely used as the primary frequency standard in many labs. The cold atom clock for satellite applications, however, has not been reported so far due to special requirements of space applications. Here, we report the development of an engineering model of a satellite-borne cold atom clock, which satisfied all requirements of in-orbit operation. The core of the clock’s principle is the laser cooling of atoms by diffuse laser lights inside the microwave cavity. The structure of the physics package is presented, and its main parameters are also given. The principle and design of the optical bench are described. The initial test results are presented, and the possible improvements are also discussed.

Experimental and DEM investigation of axially-loaded behaviours of IWP-based structures

The Schoen I-graph-wrapped package (IWP) structures are recognized as one of the best promising cellular structures because of their high specific mechanical properties and damping ratios. The axially-loaded behaviors are critical for structural safety and durability in engineering fields. In order to extend the application of IWP structures into civil engineering, this paper investigated the axially-loaded behaviors, including compressive strength, force distribution, load-deflection pattern, energy absorption and cracking pattern, of the main and secondary Skeletal-IWP structures. Firstly, a novel method for simplifying triply periodic minimal surfaces (TPMSs) has been put forward. Then the main and secondary Skeletal-IWP units are fabricated using stereolithography technology and tested. The discrete element method (DEM) is adopted, for the first time, to simulate the axially-loaded behaviors of IWP structures with different unit cell arrangements after the validation by robust experimental results. The results reveal that the secondary Skeletal-IWP structures outperform the main Skeletal-IWP structures in compressive strength. When the unit arrangement changes from single unit to 7 × 7 × 7, the compressive strength of the main and secondary Skeletal-IWP structures increases from 9 MPa to 13.4 MPa and 9.2 MPa to 14.4 MPa, respectively. The main type shows a “X”-shaped cracking pattern, and the secondary shows a “X”-shaped cracking pattern.

Design of pulse and respiration monitoring system based on fiber optic sensing and VMD-FPR processing algorithm

We propose a pulse and respiration monitoring system based on fiber optic sensing, to achieve accurate monitoring of human pulse and respiration rate with wearable and high comfort. We designed a flexible packaging structure -- to embed the fiber Bragg grating sensors (FBGs) fiber optic sensor into a nylon bandage, which constitutes a wearable real-time monitoring system that can acquire pulse and respiration rates simultaneously. The system uses the Variational Mode Decomposition - Feature Point Recognition (VMD-FPR) signal processing algorithm to demodulate and analyze the FBG echo signal to invert the pulse and respiration rate. The experiments were conducted on human heart rate and respiration rate in different states. The experimental results showed that the error range of respiration rate was within ±0.2 bpm, and the accuracy of the respiration experiment feature point recognition algorithm was 93.29 %. The error range of heart rate was within ±2 bpm, and the accuracy of the pulse experiment main wave feature point recognition algorithm was 99.28 %. Thus, the system can accurately collect and analyze the feature points in the respiratory and pulse wave signals. The information obtained from the experiments is used to build an information base, which provides data support for establishing the analysis model of pulse characteristics and respiratory characteristics of the detectors, and to achieve the function of real-time monitoring of human physiological parameters.

PyThea: An open-source software package to perform 3D reconstruction of coronal mass ejections and shock waves

PyThea is a newly developed open-source Python software package that provides tools to reconstruct coronal mass ejections (CMEs) and shocks waves in three dimensions, using multi-spacecraft remote-sensing observations. In this article, we introduce PyThea to the scientific community and provide an overview of the main functionality of the core software package and the web application. This package has been fully built in Python, with extensive use of libraries available within this language ecosystem. PyThea package provides a web application that can be used to reconstruct CMEs and shock waves. The application automatically retrieves and processes remote-sensing observations, and visualizes the imaging data that can be used for the analysis. Thanks to PyThea, the three-dimensional reconstruction of CMEs and shock waves is an easy task, with final products ready for publication. The package provides three widely used geometrical models for the reconstruction of CMEs and shocks, namely, the graduated cylindrical shell (GCS) and an ellipsoid/spheroid model. It also provides tools to process the final fittings and calculate the kinematics. The final fitting products can also be exported and reused at any time. The source code of PyThea package can be found in GitHub and Zenodo under the GNU General Public License v3.0. In this article, we present details for PyThea‘s python package structure and its core functionality, and we show how this can be used to perform three-dimensional reconstruction of coronal mass ejections and shock waves.

Program source code comprehension by module clustering using combination of discretized gray wolf and genetic algorithms

Maintenance is a critical and costly phase of software lifecycle. Understanding the structure of software will make it much easier to maintain the software. Clustering the modules of software is regarded as a useful reverse engineering technique for constructing software structural models from source code. Minimizing the connections between produced clusters, maximizing the internal connections within the clusters, and maximizing the clustering quality are the most important objectives in software module clustering. Finding the optimal software clustering model is regarded as an NP-complete problem. The low success rate, limited stability, and poor modularization quality are the main drawbacks of the previous methods. In this paper, a combination of gray wolf optimization algorithm and genetic algorithms is suggested for efficient clustering of software modules. An extensive series of experiments on 14 standard benchmarks have been conducted to evaluated the proposed method. The results illustrate that using the combination of gray wolf and genetic algorithms to the software-module clustering problem increases the quality of clustering. In terms of modularization quality and convergence speed, proposed hybrid method outperforms the other heuristic approaches.

Simulation and reliability testing of leadless package high-temperature pressure sensor

Most of the current SOI high-temperature pressure sensors are packaged in lead bonding, where the gold wire is in direct contact with the bonding bump and filled with silicone oil as a protective medium. Silicone oil expands at high temperatures, limiting the sensor's operating temperature to 150 °C or less. To solve this problem, this paper uses an anodic bonding process to bond borosilicate glass wafers to SOI wafers, which are subsequently filled with conductive silver paste and sintered at a high temperature to avoid direct contact between the leads and the chip pads. The reliability of the leadless package structure under high temperature, high pressure, and random vibration is verified by multi-field coupling stress simulation. High-temperature storage and random vibration tests were conducted according to the application requirements, and the results show that the sensor has good reliability and stability.

PyOECP: A flexible open-source software library for estimating and modeling the complex permittivity based on the open-ended coaxial probe (OECP) technique

We present PyOECP, a Python-based flexible open-source software for estimating and modeling the complex permittivity obtained from the open-ended coaxial probe (OECP) technique. The transformation of the measured reflection coefficient to complex permittivity is performed based on three different methods. The software library contains the dielectric spectra of common reference liquids, which can be used to transform the reflection coefficient into the dielectric spectra. Several Python routines that are commonly employed (e.g., SciPy and NumPy) in the field of science and engineering are required only so that the users can alter the software structure depending on their needs. The modeling algorithm exploits the Markov Chain Monte Carlo method for the data regression. The discrete relaxation models can be built by a proper combination of well-known relaxation models. In addition to these models, electrode polarization, a typical measurement artifact for interpreting dielectric spectra, can be incorporated into the modeling algorithm. A continuous relaxation model, which solves the Fredholm integral equation of the first kind (a mathematically ill-posed problem), is also included. This open-source software enables users to freely adjust the physical parameters to obtain physical insight into their materials under test and will be consistently updated for more accurate measurement and interpretation of dielectric spectra in an automated manner. This work describes the theoretical and mathematical background of the software, lays out the workflow, and validates the software functionality based on both synthetic and empirical data included in the software. Program summaryProgram title: PyOECP 0.5CPC Library link to program files:https://doi.org/10.17632/vsh6vb9cbv.1Developer's repository link:https://github.com/tyoon124Code Ocean capsule:https://codeocean.com/capsule/89645681Licensing provisions: BSD-3 Clause LicenseProgramming language: Python3External routines: Numpy, Scipy, and MatplotlibNature of problem: Estimate and interpret the frequency-dependent (complex) permittivity in fluid(s) and their mixtures based on the reflection coefficients obtained from the open-ended coaxial probe (OECP) technique. The obtained dielectric spectra can be useful for understanding the relaxation processes in an arbitrary fluid.Solution method: The reflection coefficient data is obtained as a text format from a Vector Network Analyzer (VNA). This text data is parsed into a Numpy array. Three different modules (Stuchly, Marsland, and Komarov) can be used to transform the parsed reflection coefficient data into complex permittivity as a function of the measurement frequency. The resultant dielectric spectra can be dissected and interpreted by fitting either discrete relaxation model(s) based on the Markov Chain Monte Carlo algorithm or a continuous relaxation model by applying the Zasetsky-Buchner method.

Effects of Polystrene (PS) Molecular Weight and Metal Oxide (TiO2) Content of PS Latex/TiO2 Nanocomposites on Their Film Formation Behavior

Our aim for the research described here was to investigate the effects of the molecular weight (Mw) of the polystrene (PS) latex and the nano-metal oxide (TiO2) content of PS latex/TiO2 nanocomposites on their film formation behavior. With the steady-state fluorescence (SSF) and UV-visible (UVV) techniques, the film formation was monitored through a pyrene-based fluorescence probe. Two instruments were utilized to observe the morphological alterations of the composite films: an atomic force microscope (AFM) and a scanning electron microscope (SEM). Prior to the results experiments, the composite films were prepared in two sets consisting of the latex particles with high Mw (HM) or low Mw (LM), and a dip-coating technique was used at room temperature in order to form multiple layers in each film with TiO2. Then these samples were annealed within the range of 100–280 °C, above the glass transition temperature (T g) of PS. Throughout the annealing process, the film formation was monitored stage by stage based on the fluorescence intensity (I p) emitted from added pyrene and the transmitted light intensity (I tr) levels. All the measurements resulted in completion of film formation, independent of the Mw of the PS latexes or the TiO2 content. However, while the void closure process was not observed in the LM films, whose packaging structure was much simpler than that of the HM films, it was observed in the HM films. At the end of the process, a porous structure was obtained by extracting the PS polymer using toluene as the solvent. The surface appearance of the sample films varied according to both the different amounts of TiO2 layers in the composite films and the molecular weight of the PS latexes. For the HM films, interconnected porosity was produced at all TiO2 contents, whereas interconnected pores were not observed for more than 5 TiO2 layers contents in the LM samples. Furthermore, the spectroscopic measurements and the SEM/AFM images indicated that the film formation of the PS latexes took place primarily in the PS layers on the top and bottom film surfaces.

Equivalent Modeling of Microbump Layer in Microsystem for Thermal Analysis Based on Differential Idea

The through-silicon-vias (TSV) packaging structure in the microsystem is complex, especially there are a large number of microbumps. Meanwhile, the microsystem structure size has a cross-scale problem. Then, detailed modeling will bring difficulties in meshing and simulation calculation efficiency. Based on the actual bump structure in the microbump layer, a calculating method for the anisotropy equivalent thermal conductivity of the microbump layer is proposed by using differential ideas combined with the heat transfer theory. The thermal simulation analysis of the detailed model and the equivalent model is completed. The comparison simulation results show that the equivalent modeling method has high accuracy and greatly calculation efficiency. By comparing the thermal test result, the simulation result is basically consistent with the test result, which verified the accuracy of the equivalent modeling method again. Later, the influence of the bump radius, the bump pitch, and the microbump layer height on the equivalent thermal conductivity of the microbump layer is mainly studied, which provides theoretical support on thermal design for the microbump layer in the microsystem.

Novel Integration Techniques for Gap Waveguides and MMICs Suitable for Multilayer Waveguide Applications

This article discusses three integration and packaging techniques for gap waveguides and monolithic microwave integrated circuits (MMICs) suitable for multilayer waveguide applications. Two vertical transitions between microstrips and ridge gap waveguides (RGWs) are presented. The first vertical transition connects RGW to a microstrip line from the top where a rectangular patch has been used. Measured results of the transition in a back-to-back structure show that the reflection coefficient is better than −10 dB from 75 to 83 GHz, and the insertion loss for a single transition over the frequency band is 0.65–0.85 dB. The second vertical transition connects RGW to a microstrip line from the back by a slot in the ground plane. Measured results of the transition in a back-to-back structure show that the reflection coefficient is better than −10 dB from 69 to 86 GHz, and the insertion loss for a single transition is 0.65–1 dB over the frequency band. Commercially available E-band MMIC amplifiers are integrated with RGWs using the two proposed transitions. Moreover, for the very first time, the integration of MMIC with inverted microstrip gap waveguide (IMGW) is realized by a compact packaging structure that utilizes bond wires and capacitive pads. All the three active integrations are consistent with the passive measurements in terms of operational bandwidth, losses, amplifier gain flatness, and unwanted resonance suppression.

Long term accumulation of heat energy from the sun

The source of hot water production for the investigated storage tanks are solar collectors. Solar collectors provide recharging of underground storage tanks all year round. Due to the large active area of solar collectors - 225 m2, there are also large tanks for long-term accumulation. Accumulation tanks are in 3 sizes with a total volume of 160 m3. With regard to the size of the tanks, the mode is switched between the tanks according to the season. The tanks are made of a reinforced concrete packaging structure and are stored under the terrain of the Center of Research anf Innovation in Construction (CVIS laboratory).

Prediction on Thermal Cycling Stress of PBGA Package Based on Finite Element Simulation and Machine Learning

As the application environment of Plastic Ball Grid Array (PBGA) package becomes more diverse and severe, higher requirements are placed on the thermal cycling reliability of the PBGA package. The thermal cycling reliability of PBGA package has higher standards. The traditional experimental method has the problems of a long cycle and high costs. In this paper, the thermal cycling stress of the PBGA package is studied based on finite element simulation and machine learning methods. Take the typical PBGA package structure solder ball as the research object, and simulate the solder ball stress value under extreme thermal cycling conditions using the finite element software ABAQUS. The dataset is organized based on the finite element analysis results to establish a machine learning prediction model, which aims to predict the thermal cycling stress of PBGA package rapidly. The result shows that the prediction model established by the Random Forest Regression (RFR) algorithm has better prediction accuracy compared with Multiple Linear Regression (MLR) algorithm and Support Vector Regression (SVR) algorithm, and the Mean Absolute Percent Error (MAPE) is 3.01%, which can provide a new way to predict thermal cycling stress of PBGA packages directly.

Polymorphic wireless receivers

Today's wireless technologies are largely based on inflexible designs, which make them inefficient and prone to a variety of wireless attacks. To address this key issue, wireless receivers will need to (i) infer on-the-fly the physical layer parameters currently used by transmitters; and if needed, (ii) change their hardware and software structures to demodulate the incoming waveform. In this paper, we introduce PolymoRF , a deep learning-based polymorphic receiver able to reconfigure itself in real time based on the inferred waveform parameters. Our key technical innovations are (i) a novel embedded deep learning architecture, called RFNet , which enables the solution of key waveform inference problems, and (ii) a generalized hardware/software architecture that integrates RFNet with radio components and signal processing. We prototype PolymoRF on a custom software-defined radio platform and show through extensive over-the-air experiments that PolymoRF achieves throughput within 87% of a perfect-knowledge Oracle system, thus demonstrating for the first time that polymorphic receivers are feasible.

An Automatic Finite Element Method-Boundary Element Method Coupling Method for Elastic–Plastic Problems of Multiscale Structures in Electronic Packaging

Abstract We introduce a coupled finite and boundary element method for elastic-plastic analysis over multiscale electronic packaging structures. Based on the finite element-boundary element (FE-BE) coupling algorithm, an automatic implementation procedure for the coupling of the abaqus with a self-written elastic BE code is introduced for elastic problems. In the mixed finite element method (FEM)-boundary element method (BEM) model, the effective stiffness and effective forces at the interfacial boundary are evaluated by the self-written BE code. Then, the obtained effective stiffness and effective forces are assembled to the global FE formulations by using the user subroutine (UEL) in abaqus. Numerical simulation of structures with plastic deformation, stress concentration, etc. is carried out by using FEM theory. The boundary element method is used for linear elastic domains with large-scale structures. The proposed method offers several key improvements compared with current analysis methods available for multiscale electronic packaging structures. The benefits are: (i) the powerful pre- and postprocessing of abaqus; (ii) the higher accuracy of the solution; (iii) the computational cost and time can be reduced by using the scheme; and (iv) solving systems with infinite extension by using the BEM as a supplement. Furthermore, we demonstrate the ability of the proposed approach to handle multiscale structures in electronic packaging problems.

Advances in Polyethylene Terephthalate Beverage Bottle Optimization: A Mini Review.

Compared with other materials, polyethylene terephthalate (PET) has high transparency, excellent physical and mechanical properties in a wide temperature range and good hygiene and safety, so it is widely used in the packaging industry, especially in the packaging of beverages and foods. The optimization of PET bottles is mainly reflected in three aspects: material optimization, structure optimization and process optimization, among which there is much research on material optimization and process optimization, but there is no complete overview on structure optimization. A summary of structural optimization is necessary. Aiming at structural optimization, the finite element method is a useful supplement to the beverage packaging industry. By combining the computer-aided design technology and using finite element software for finite element simulation, researchers can replace the experimental test in the pre-research design stage, predict the effect and save cost. This review summarizes the development of PET bottles for beverage packaging, summarizes various optimization methods for preventing stress cracking in beverage packaging, and especially focuses on comparing and evaluating the effects of several optimization methods for packaging structure. Finally, the future development of all kinds of optimization based on structural optimization in the field of beverage packaging is comprehensively discussed, including personalized design, the combination of various methods and the introduction of actual impact factor calculation.