다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.

Additive manufacturing (3D printing): A review of materials, methods, applications and challenges

A strain sensor has been fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers. The piezoresistivity
of this nanocomposite strain sensor has been investigated based on an improved three-dimensional (3D) statistical resistor network
model incorporating the tunneling effect between the neighboring carbon nanotubes (CNTs), and a fiber reorientation model. The
numerical results agree very well with the experimental measurements. As compared with traditional strain gauges, much higher sensitivity
can be obtained in the nanocomposite sensors when the volume fraction of CNT is close to the percolation threshold. For a small
CNT volume fraction, weak nonlinear piezoresistivity is observed both experimentally and from numerical simulation. The tunneling
effect is considered to be the principal mechanism of the sensor under small strains.

Tunneling effect in a polymer/carbon nanotube nanocompositestrain sensor

A review : On the development of low melting temperature Pb-free solders

Composite lead-free solders, containing micro and nano particles, have been widely studied. Due to grain boundary drag or Zener drag, these particles can refrain the solder microstructure from coarsening in services, especially for Cu6Sn5, Ag3Sn intermetallic compounds and the β-Sn phases. Due to dispersion hardening or dislocation drag, the mechanical properties of the composite solder alloys were enhanced significantly. Moreover, these particles can influence the rate of interfacial reactions, and some particles can transform into a layer of intermetallic compound. Wettability, creep resistance, and hardness properties were affected by these particles. A systematic review of the development of these lead-free composite solders is given here, which hopefully may find applications in microbumps to be used in the future 3D IC technology.

Structure and properties of lead-free solders bearing micro and nano particles

The planar fluxgate is an emerging technology feasible for system integration contrary to it’s bulky 3D counterpart. Recently, a novel structure based on an asymmetric double core layout for improved sensitivity and energy efficiency was proposed. The aim of this paper is, for the first time, to conduct a direct experimental comparison between single- and asymmetric double-core structures. The results confirm the original conjecture and show that asymmetric double core structures can easily boost the sensitivity by a factor of two for similar power supply.

https://www.mdpi.com/2504-3900/2/13/831/pdf

Analysis of Single- and Double Core Planar Fluxgate Structures

Fine-pitch flip-chip bonding with a low-temperature budget can be considered not only as the key enabler of hybrid and flexible electronics, but also as a requirement for 3D packaging platforms with temperaturesensitive components. In this study, low-temperature flip chip bonding by using snap cure non-conductive paste (NCP) and anisotropic conductive paste (ACP) was investigated. By exploiting the compliancy of soft gold-studbumps and compressive stress induced by snap cure adhesives, flip-chip bonding with both adhesives were successfully conducted in a thermode station at 170°C within a few seconds. It was also found out, that for finepitch flip-chip bonding with Au-stud bumps, snap cure NCA is the better choice, since it can handle finer pitches, provide sufficient underfilling, has lower cost and simplified process.

Low-Temperature fine-pitch flip-chip bonding by using snap cure adhesives and Au stud bumps

With the ongoing trend toward miniaturization via system-on-chip (SoC), both radio-frequency (RF) SoCs and on-chip multi-sensory systems are gaining significance. This paper compares the inductance of a miniaturized on-chip near field communication (NFC) antenna versus the conventional screen-printed on-substrate ones that have been used for the transfer of sensory data from a chip to a cell phone reader. Furthermore, the transferred power efficiency in a coupled NFC system is calculated for various chip coil geometries and the results are compared. The proposed NFC antenna was fabricated via a lithography process for an application-specific integrated circuit (ASIC) chip. The chip had a small area of 2.4 × 2.4 mm2, therefore a miniaturized NFC antenna was designed, whereas the screen-printed on-substrate antennas had an area of 35 × 51 mm2. This paper investigates the effects of different parameters such as conductor thickness and materials, double layering, and employing ferrite layers with different thicknesses on the performance of the on-chip antennas using full-wave simulations. The presence of a ferrite layer to increase the inductance of the antenna and mitigate the interactions with backplates has proven useful. The best performance was obtained via double-layering of the coils, which was similar to on-substrate antennas, while a size reduction of 99.68% was gained. Consequently, the coupling factors and maximum achievable power transmission efficiency of the on-chip antenna and on-substrate antenna were studied and compared.

https://www.mdpi.com/2624-831X/1/2/18/pdf

Miniaturized On-Chip NFC Antenna versus Screen-Printed Antenna for the Flexible Disposable Sensor Strips

A survey of high temperature die-attach solutions for lithium niobate (LiNbO3) single crystals was conducted and based on that three promising approaches; i.e. eutectic solder, silver sinter-paste and silver-loaded conductive adhesive; were proposed and investigated. A relatively low pressure span (0–4 MPa) was employed, aiming to mitigate the risk of fracture in the brittle die. The mechanical properties of the corresponding die-attach assemblies was examined by a die-shear tester and the reliability of the joints was assessed after isothermal aging at 300 °C. The micro-structural integrity of the bonding was also analyzed by cross-sectional microscopy. The results revealed that silver sinter paste die-attach possesses superior shear strength in comparison to the two other techniques. Cross-sectional failure analysis also indicated a ductile fracture mode throughout the bonding layer for silver-paste and adhesive joints, whereas in soldered assemblies a brittle fracture mode along the interfacial intermetallic compound layer was predominant.

High temperature MEMS packages: die-attach solutions for LiNbO3 under low bonding pressures

An Artificial Neural Network (ANN) model has been designed for predicting the effects of alloying elements (Fe, Si, Al, Mn) on the recrystallization behavior and microstructural changes of 70/30 brass. The model introduced here considers the content of alloying elements, temperature, and time of recrystallization as inputs while percent of recrystallization is presented as output. It is shown that the designed model is able to predict the effect of alloying elements well. It is also shown that all alloying elements strongly affect the recrytallization kinetics, and all slow down the recrystallization process. The effect of alloying elements on the activation energy for recrystallization has also been investigated. The results show that Si is the element which increases the activation energy.

Ali Roshanghias

Papers

Analysis of Single- and Double Core Planar Fluxgate Structures

Low-Temperature fine-pitch flip-chip bonding by using snap cure adhesives and Au stud bumps

Miniaturized On-Chip NFC Antenna versus Screen-Printed Antenna for the Flexible Disposable Sensor Strips

High temperature MEMS packages: die-attach solutions for LiNbO3 under low bonding pressures

An Investigation into the Effect of Alloying Elements on the Recrystallization Behavior of 70/30 Brass